Commonwealth Edison 10-Q4 Aug 212021 Q2 Quarterly reportFinancial data

Company Profile

Cover Page

Cover Page	6 Months Ended
Cover Page	Jun. 30, 2021shares
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Jun. 30, 2021
Document Transition Report	false
Entity File Number	001-16169
Entity Registrant Name	EXELON CORPORATION
Entity Tax Identification Number	23-2990190
Entity Incorporation, State or Country Code	PA
Entity Address, Address Line One	10 South Dearborn Street
Entity Address, Address Line Two	P.O. Box 805379
Entity Address, City or Town	Chicago
Entity Address, State or Province	IL
Entity Address, Postal Zip Code	60680-5379
City Area Code	(800)
Local Phone Number	483-3220
Title of 12(b) Security	Common stock, without par value
Trading Symbol	EXC
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock Shares Outstanding	977,832,660
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q2
Current Fiscal Year End Date	--12-31
Entity Central Index Key	0001109357
Amendment Flag	false
Exelon Generation Co L L C [Member]
Entity File Number	333-85496
Entity Registrant Name	EXELON GENERATION COMPANY, LLC
Entity Tax Identification Number	23-3064219
Entity Incorporation, State or Country Code	PA
Entity Address, Address Line One	300 Exelon Way
Entity Address, City or Town	Kennett Square
Entity Address, State or Province	PA
Entity Address, Postal Zip Code	19348-2473
City Area Code	(610)
Local Phone Number	765-5959
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Central Index Key	0001168165
Commonwealth Edison Co [Member]
Entity File Number	001-01839
Entity Registrant Name	COMMONWEALTH EDISON COMPANY
Entity Tax Identification Number	36-0938600
Entity Incorporation, State or Country Code	IL
Entity Address, Address Line One	440 South LaSalle Street
Entity Address, City or Town	Chicago
Entity Address, State or Province	IL
Entity Address, Postal Zip Code	60605-1028
City Area Code	(312)
Local Phone Number	394-4321
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Common Stock Shares Outstanding	127,021,380
Entity Central Index Key	0000022606
PECO Energy Co [Member]
Entity File Number	000-16844
Entity Registrant Name	PECO ENERGY COMPANY
Entity Tax Identification Number	23-0970240
Entity Incorporation, State or Country Code	PA
Entity Address, Address Line One	P.O. Box 8699
Entity Address, Address Line Two	2301 Market Street
Entity Address, City or Town	Philadelphia
Entity Address, State or Province	PA
Entity Address, Postal Zip Code	19101-8699
City Area Code	(215)
Local Phone Number	841-4000
Title of 12(b) Security	Cumulative Preferred Security, Series D
Trading Symbol	EXC/28
Security Exchange Name	NYSE
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Common Stock Shares Outstanding	170,478,507
Entity Central Index Key	0000078100
Baltimore Gas and Electric Company [Member]
Entity File Number	001-01910
Entity Registrant Name	BALTIMORE GAS AND ELECTRIC COMPANY
Entity Tax Identification Number	52-0280210
Entity Incorporation, State or Country Code	MD
Entity Address, Address Line One	2 Center Plaza
Entity Address, Address Line Two	110 West Fayette Street
Entity Address, City or Town	Baltimore
Entity Address, State or Province	MD
Entity Address, Postal Zip Code	21201-3708
City Area Code	(410)
Local Phone Number	234-5000
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Common Stock Shares Outstanding	1,000
Entity Central Index Key	0000009466
Pepco Holdings LLC [Member]
Entity File Number	001-31403
Entity Registrant Name	PEPCO HOLDINGS LLC
Entity Tax Identification Number	52-2297449
Entity Incorporation, State or Country Code	DE
Entity Address, Address Line One	701 Ninth Street, N.W.
Entity Address, City or Town	Washington, District of Columbia
Entity Address, Postal Zip Code	20068
City Area Code	(202)
Local Phone Number	872-2000
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Central Index Key	0001135971
Potomac Electric Power Company [Member]
Entity File Number	001-01072
Entity Registrant Name	POTOMAC ELECTRIC POWER COMPANY
Entity Tax Identification Number	53-0127880
Entity Address, Address Line One	701 Ninth Street, N.W.
Entity Address, City or Town	Washington, District of Columbia
Entity Address, Postal Zip Code	20068
City Area Code	(202)
Local Phone Number	872-2000
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Common Stock Shares Outstanding	100
Entity Central Index Key	0000079732
Delmarva Power and Light Company [Member]
Entity File Number	001-01405
Entity Registrant Name	DELMARVA POWER & LIGHT COMPANY
Entity Tax Identification Number	51-0084283
Entity Address, Address Line One	500 North Wakefield Drive
Entity Address, City or Town	Newark
Entity Address, State or Province	DE
Entity Address, Postal Zip Code	19702
City Area Code	(202)
Local Phone Number	872-2000
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Common Stock Shares Outstanding	1,000
Entity Central Index Key	0000027879
Atlantic City Electric Company [Member]
Entity File Number	001-03559
Entity Registrant Name	ATLANTIC CITY ELECTRIC COMPANY
Entity Tax Identification Number	21-0398280
Entity Incorporation, State or Country Code	NJ
Entity Address, Address Line One	500 North Wakefield Drive
Entity Address, City or Town	Newark
Entity Address, State or Province	DE
Entity Address, Postal Zip Code	19702
City Area Code	(202)
Local Phone Number	872-2000
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Common Stock Shares Outstanding	8,546,017
Entity Central Index Key	0000008192
DISTRICT OF COLUMBIA \| Potomac Electric Power Company [Member]
Entity Incorporation, State or Country Code	DC
VIRGINIA \| Potomac Electric Power Company [Member]
Entity Incorporation, State or Country Code	VA
VIRGINIA \| Delmarva Power and Light Company [Member]
Entity Incorporation, State or Country Code	VA
DELAWARE \| Delmarva Power and Light Company [Member]
Entity Incorporation, State or Country Code	DE

Consolidated Statements of Oper

Consolidated Statements of Operations and Comprehensive Income (Unaudited) - USD ($) shares in Millions, $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Operating revenues
Revenues from alternative revenue programs		$ 47	$ (122)	$ 176	$ (55)
Operating revenues from affiliates		0	1	0	2
Total operating revenues		7,915	7,322	17,805	16,069
Operating expenses
Operating and maintenance		2,447	2,433	4,426	4,637
Depreciation and amortization		1,666	1,001	3,363	2,023
Taxes other than income taxes		432	411	870	847
Total operating expenses		7,561	6,769	17,643	14,298
Gain on sales of assets and businesses		12	12	83	13
Operating income (loss)		366	565	245	1,784
Other income and (deductions)
Interest expense, net		(390)	(421)	(770)	(824)
Interest expense to affiliates		(6)	(6)	(13)	(13)
Other, net		581	656	806	(68)
Total other income and (deductions)		185	229	23	(905)
Income before income taxes		551	794	268	879
Income taxes		74	219	55	(75)
Equity in losses of unconsolidated affiliates		(1)	(1)	(2)	(4)
Net income (loss)		476	574	211	950
Net income (loss) attributable to noncontrolling interests		75	53	99	(153)
Net Income (Loss) Available to Common Stockholders, Basic		401	521	112	1,103
Other comprehensive income (loss), net of income taxes
Prior service benefit reclassified to periodic benefit cost		(1)	(10)	(2)	(20)
Actuarial loss reclassified to periodic benefit cost		56	47	112	94
Pension and non-pension postretirement benefit plan valuation adjustment		0	2	(2)	(5)
Unrealized (loss) gain on cash flow hedges		0	0	0	(1)
Unrealized gain (loss) on foreign currency translation		2	2	3	(6)
Other comprehensive income		57	41	111	62
Comprehensive income		533	615	322	1,012
Comprehensive income (loss) attributable to noncontrolling interests		75	53	99	(153)
Comprehensive income attributable to common shareholders/membership interest		$ 458	$ 562	$ 223	$ 1,165
Average shares of common stock outstanding:
Basic average shares of common stock outstanding		978	976	978	975
Assumed exercise and/or distributions of stock-based awards		1	0	1	1
Diluted average shares of common stock outstanding	[1]	979	976	979	976
Earnings per average common share
Basic earnings per average common share		$ 0.41	$ 0.53	$ 0.11	$ 1.13
Diluted earnings per average common share		$ 0.41	$ 0.53	$ 0.11	$ 1.13
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount		0	1	0	0
Exelon Generation Co L L C [Member]
Operating revenues
Operating revenues from affiliates		$ 254	$ 271	$ 549	$ 601
Total operating revenues		4,153	3,880	9,712	8,613
Operating expenses
Purchased power and fuel from affiliates		(5)	(3)	(5)	(9)
Operating and maintenance		1,337	1,053	2,194	2,174
Operating and maintenance from affiliates		137	136	282	277
Depreciation and amortization		930	300	1,869	604
Taxes other than income taxes		118	116	239	246
Total operating expenses		4,469	3,547	11,141	7,947
Gain on sales of assets and businesses		8	12	79	12
Operating income (loss)		(308)	345	(1,350)	678
Other income and (deductions)
Interest expense, net		(72)	(78)	(140)	(179)
Interest expense to affiliates		(4)	(9)	(8)	(18)
Other, net		508	602	675	(168)
Total other income and (deductions)		432	515	527	(365)
Income before income taxes		124	860	(823)	313
Income taxes		110	329	(70)	(59)
Equity in losses of unconsolidated affiliates		(1)	(2)	(3)	(4)
Net income (loss)		13	529	(756)	368
Net income (loss) attributable to noncontrolling interests		74	53	98	(153)
Net income attributable to membership interest		(61)	476	(854)	521
Other comprehensive income (loss), net of income taxes
Unrealized (loss) gain on cash flow hedges		0	0	0	(1)
Unrealized gain (loss) on foreign currency translation		2	2	3	(6)
Other comprehensive income		2	2	3	(7)
Comprehensive income		15	531	(753)	361
Comprehensive income (loss) attributable to noncontrolling interests		74	53	98	(153)
Comprehensive income attributable to common shareholders/membership interest		(59)	478	(851)	514
Commonwealth Edison Co [Member]
Operating revenues
Revenues from alternative revenue programs		9	(25)	64	(13)
Operating revenues from affiliates		5	11	11	16
Total operating revenues		1,517	1,417	3,052	2,856
Operating expenses
Purchased power and/or fuel from affiliates		79	84	163	181
Operating and maintenance		250	469	495	713
Operating and maintenance from affiliates		73	67	144	140
Depreciation and amortization		296	274	589	547
Taxes other than income taxes		77	71	153	146
Total operating expenses		1,196	1,345	2,406	2,497
Operating income (loss)		321	72	646	359
Other income and (deductions)
Interest expense, net		(95)	(95)	(187)	(186)
Interest expense to affiliates		(3)	(3)	(6)	(6)
Other, net		15	11	22	22
Total other income and (deductions)		(83)	(87)	(171)	(170)
Income before income taxes		238	(15)	475	189
Income taxes		46	46	85	82
Net income (loss)		192	(61)	390	107
Other comprehensive income (loss), net of income taxes
Comprehensive income		192	(61)	390	107
PECO Energy Co [Member]
Operating revenues
Revenues from alternative revenue programs		7	4	17	5
Operating revenues from affiliates		2	2	4	4
Total operating revenues		693	681	1,582	1,493
Operating expenses
Purchased power and/or fuel from affiliates		40	40	81	76
Operating and maintenance		166	235	360	414
Operating and maintenance from affiliates		43	40	83	78
Depreciation and amortization		87	88	173	173
Taxes other than income taxes		49	39	92	78
Total operating expenses		552	618	1,231	1,242
Operating income (loss)		141	63	351	251
Other income and (deductions)
Interest expense, net		(39)	(33)	(74)	(65)
Interest expense to affiliates		(3)	(3)	(6)	(6)
Other, net		7	5	12	7
Total other income and (deductions)		(35)	(31)	(68)	(64)
Income before income taxes		106	32	283	187
Income taxes		2	(7)	12	9
Net income (loss)		104	39	271	178
Other comprehensive income (loss), net of income taxes
Comprehensive income		104	39	271	178
Baltimore Gas and Electric Company [Member]
Operating revenues
Revenues from alternative revenue programs		(10)	(37)	8	0
Operating revenues from affiliates		7	4	13	10
Total operating revenues		682	616	1,656	1,554
Operating expenses
Purchased power and/or fuel from affiliates		59	69	129	167
Operating and maintenance		147	146	299	293
Operating and maintenance from affiliates		46	41	91	83
Depreciation and amortization		141	129	293	272
Taxes other than income taxes		67	63	139	132
Total operating expenses		620	573	1,372	1,263
Operating income (loss)		62	43	284	291
Other income and (deductions)
Interest expense, net		(34)	(32)	(67)	(64)
Other, net		9	6	16	10
Total other income and (deductions)		(25)	(26)	(51)	(54)
Income before income taxes		37	17	233	237
Income taxes		(8)	(22)	(21)	18
Net income (loss)		45	39	254	219
Other comprehensive income (loss), net of income taxes
Comprehensive income		45	39	254	219
Pepco Holdings LLC [Member]
Operating revenues
Revenues from alternative revenue programs		41	(64)	88	(47)
Operating revenues from affiliates		4	3	7	7
Total operating revenues		1,140	1,016	2,384	2,187
Operating expenses
Purchased power and/or fuel from affiliates		79	78	177	182
Operating and maintenance		217	245	434	464
Operating and maintenance from affiliates		39	36	79	74
Depreciation and amortization		194	191	404	385
Taxes other than income taxes		109	109	222	222
Total operating expenses		955	956	2,013	1,955
Gain on sales of assets and businesses		0	0	0	2
Operating income (loss)		185	60	371	234
Other income and (deductions)
Interest expense, net		(67)	(67)	(134)	(134)
Other, net		20	14	36	26
Total other income and (deductions)		(47)	(53)	(98)	(108)
Income before income taxes		138	7	273	126
Income taxes		(3)	(87)	5	(76)
Equity in losses of unconsolidated affiliates		0	0	1	0
Net income (loss)		141	94	269	202
Other comprehensive income (loss), net of income taxes
Comprehensive income attributable to common shareholders/membership interest		141	94	269	202
Potomac Electric Power Company [Member]
Operating revenues
Revenues from alternative revenue programs		19	(13)	46	2
Operating revenues from affiliates		1	1	3	3
Total operating revenues		523	494	1,076	1,039
Operating expenses
Purchased power and/or fuel from affiliates		57	60	130	139
Operating and maintenance		62	67	118	128
Operating and maintenance from affiliates		51	52	103	103
Depreciation and amortization		96	92	199	186
Taxes other than income taxes		87	87	177	179
Total operating expenses		429	436	895	899
Operating income (loss)		94	58	181	140
Other income and (deductions)
Interest expense, net		(35)	(34)	(69)	(68)
Other, net		13	9	25	18
Total other income and (deductions)		(22)	(25)	(44)	(50)
Income before income taxes		72	33	137	90
Income taxes		(3)	(24)	3	(19)
Net income (loss)		75	57	134	109
Other comprehensive income (loss), net of income taxes
Comprehensive income		75	57	134	109
Delmarva Power and Light Company [Member]
Operating revenues
Revenues from alternative revenue programs		10	(25)	19	(24)
Operating revenues from affiliates		2	2	4	4
Total operating revenues		298	267	680	617
Operating expenses
Purchased power and/or fuel from affiliates		17	16	37	38
Operating and maintenance		41	54	85	97
Operating and maintenance from affiliates		39	38	79	75
Depreciation and amortization		51	47	104	94
Taxes other than income taxes		16	17	33	32
Total operating expenses		255	263	564	547
Operating income (loss)		43	4	116	70
Other income and (deductions)
Interest expense, net		(16)	(15)	(30)	(31)
Other, net		4	2	6	5
Total other income and (deductions)		(12)	(13)	(24)	(26)
Income before income taxes		31	(9)	92	44
Income taxes		1	(28)	6	(20)
Net income (loss)		30	19	86	64
Other comprehensive income (loss), net of income taxes
Comprehensive income		30	19	86	64
Atlantic City Electric Company [Member]
Operating revenues
Revenues from alternative revenue programs		12	(26)	23	(25)
Operating revenues from affiliates		1	1	1	1
Total operating revenues		319	256	629	532
Operating expenses
Purchased power and/or fuel from affiliates		5	2	9	5
Operating and maintenance		39	48	82	94
Operating and maintenance from affiliates		34	34	68	66
Depreciation and amortization		40	44	87	86
Taxes other than income taxes		2	2	4	4
Total operating expenses		269	258	552	509
Gain on sales of assets and businesses		0	0	0	2
Operating income (loss)		50	(2)	77	25
Other income and (deductions)
Interest expense, net		(14)	(15)	(29)	(29)
Other, net		0	2	2	3
Total other income and (deductions)		(14)	(13)	(27)	(26)
Income before income taxes		36	(15)	50	(1)
Income taxes		(1)	(33)	(1)	(32)
Net income (loss)		37	18	51	31
Other comprehensive income (loss), net of income taxes
Comprehensive income		37	18	51	31
Generation commodities and services
Operating revenues
Revenue from Contract with Customer, Including Assessed Tax		3,900	3,612	9,165	8,016
Operating expenses
Purchased power and/or fuel		1,952	1,945	6,562	4,655
Generation commodities and services \| Exelon Generation Co L L C [Member]
Operating revenues
Revenue from Contract with Customer, Including Assessed Tax		3,899	3,609	9,163	8,012
Operating expenses
Purchased power and/or fuel		1,952	1,945	6,562	4,655
Rate-regulated utility revenues
Operating revenues
Revenue from Contract with Customer, Including Assessed Tax		3,968	3,832	8,464	8,108
Operating expenses
Purchased power and/or fuel		1,064	979	2,422	2,136
Electricity, US Regulated
Operating revenues
Revenue from Contract with Customer, Including Assessed Tax		3,787	3,475	7,775	7,222
Electricity, US Regulated \| Commonwealth Edison Co [Member]
Operating revenues
Revenue from Contract with Customer, Including Assessed Tax		1,503	1,431	2,977	2,853
Operating expenses
Purchased power and/or fuel		421	380	862	770
Electricity, US Regulated \| PECO Energy Co [Member]
Operating revenues
Revenue from Contract with Customer, Including Assessed Tax		602	580	1,251	1,180
Operating expenses
Purchased power and/or fuel		145	142	334	306
Electricity, US Regulated \| Baltimore Gas and Electric Company [Member]
Operating revenues
Revenue from Contract with Customer, Including Assessed Tax		560	530	1,180	1,125
Operating expenses
Purchased power and/or fuel		133	107	295	221
Electricity, US Regulated \| Pepco Holdings LLC [Member]
Operating revenues
Revenue from Contract with Customer, Including Assessed Tax		1,071	1,047	2,195	2,133
Operating expenses
Purchased power and/or fuel		308	286	656	586
Electricity, US Regulated \| Potomac Electric Power Company [Member]
Operating revenues
Revenue from Contract with Customer, Including Assessed Tax		503	506	1,027	1,034
Operating expenses
Purchased power and/or fuel		76	78	168	164
Electricity, US Regulated \| Delmarva Power and Light Company [Member]
Operating revenues
Revenue from Contract with Customer, Including Assessed Tax		262	260	562	543
Operating expenses
Purchased power and/or fuel		82	80	185	169
Electricity, US Regulated \| Atlantic City Electric Company [Member]
Operating revenues
Revenue from Contract with Customer, Including Assessed Tax		306	281	605	556
Operating expenses
Purchased power and/or fuel		149	128	302	254
Natural Gas, US Regulated
Operating revenues
Revenue from Contract with Customer, Including Assessed Tax		228	236	865	832
Natural Gas, US Regulated \| PECO Energy Co [Member]
Operating revenues
Revenue from Contract with Customer, Including Assessed Tax		82	95	310	304
Operating expenses
Purchased power and/or fuel		22	34	108	117
Natural Gas, US Regulated \| Baltimore Gas and Electric Company [Member]
Operating revenues
Revenue from Contract with Customer, Including Assessed Tax		125	119	455	419
Operating expenses
Purchased power and/or fuel		27	18	126	95
Natural Gas, US Regulated \| Pepco Holdings LLC [Member]
Operating revenues
Revenue from Contract with Customer, Including Assessed Tax		24	30	94	94
Operating expenses
Purchased power and/or fuel		9	11	41	42
Natural Gas, US Regulated \| Delmarva Power and Light Company [Member]
Operating revenues
Revenue from Contract with Customer, Including Assessed Tax		24	30	95	94
Operating expenses
Purchased power and/or fuel		$ 9	$ 11	$ 41	$ 42

[1]	The number of stock options not included in the calculation of diluted common shares outstanding due to their antidilutive effect was zero for the three and six months ended June 30, 2021 and 1 million and less than 1 million for the three and six months ended June 30, 2020, respectively.

Consolidated Statements of Cash

Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Cash flows from operating activities
Net income (loss)	$ 211	$ 950
Adjustments to reconcile net income to net cash flows provided by operating activities:
Depreciation, amortization, and accretion, including nuclear fuel and energy contract amortization	4,180	2,741
Asset impairments	500	33
Gain on sales of assets and businesses	(83)	(13)
Deferred income taxes and amortization of investment tax credits	(163)	33
Net fair value changes related to derivatives	(490)	(194)
Net realized and unrealized (gains) losses on NDT funds	(376)	196
Unrealized loss on equity investments	(96)	0
Other non-cash operating activities	(331)	671
Changes in assets and liabilities:
Accounts receivable	(16)	1,318
Inventories	1	(14)
Accounts payable and accrued expenses	(87)	(798)
Option premiums received (paid), net	2	(102)
Collateral received (posted), net	957	340
Income taxes	190	(114)
Pension and non-pension postretirement benefit contributions	(559)	(558)
Other assets and liabilities	(2,702)	(1,809)
Net cash flows provided by operating activities	1,138	2,680
Cash flows from investing activities
Capital expenditures	(4,040)	(3,773)
Proceeds from NDT fund sales	4,438	2,488
Investment in NDT funds	(4,538)	(2,540)
Collection of deferred purchase price	2,209	1,102
Proceeds from sales of assets and businesses	724	0
Other investing activities	17	4
Net cash flows provided by (used in) investing activities	(1,190)	(2,719)
Cash flows from financing activities
Changes in short-term borrowings	(666)	(751)
Proceeds from short-term borrowings with maturities greater than 90 days	500	500
Issuance of long-term debt	2,455	6,526
Retirement of long-term debt	(630)	(3,894)
Dividends paid on common stock	(747)	(746)
Proceeds from employee stock plans	47	46
Other financing activities	(64)	(84)
Net cash flows provided by (used in) financing activities	895	1,597
Increase (decrease) in cash, restricted cash, and cash equivalents	843	1,558
Cash, restricted cash, and cash equivalents at beginning of period	1,166	1,122
Cash, restricted cash, and cash equivalents at end of period	2,009	2,680
Supplemental Cash Flow Information
Increase (decrease) in capital expenditures not paid	(313)	(105)
Increase in deferred purchase price	1,958	1,754
Exelon Generation Co L L C [Member]
Cash flows from operating activities
Net income (loss)	(756)	368
Adjustments to reconcile net income to net cash flows provided by operating activities:
Depreciation, amortization, and accretion, including nuclear fuel and energy contract amortization	2,686	1,320
Asset impairments	493	18
Gain on sales of assets and businesses	(79)	(12)
Deferred income taxes and amortization of investment tax credits	(142)	(54)
Net fair value changes related to derivatives	(490)	(193)
Net realized and unrealized (gains) losses on NDT funds	(376)	196
Unrealized loss on equity investments	(96)	0
Other non-cash operating activities	(421)	136
Changes in assets and liabilities:
Accounts receivable	(90)	1,443
Receivables from and payables to affiliates, net	43	68
Inventories	4	(34)
Accounts payable and accrued expenses	154	(666)
Option premiums received (paid), net	2	(102)
Collateral received (posted), net	955	342
Income taxes	(1)	26
Pension and non-pension postretirement benefit contributions	(212)	(243)
Other assets and liabilities	(2,031)	(1,332)
Net cash flows provided by operating activities	(357)	1,281
Cash flows from investing activities
Capital expenditures	(719)	(930)
Proceeds from NDT fund sales	4,438	2,488
Investment in NDT funds	(4,538)	(2,540)
Collection of deferred purchase price	2,209	1,102
Proceeds from sales of assets and businesses	724	0
Other investing activities	(8)	6
Net cash flows provided by (used in) investing activities	2,106	126
Cash flows from financing activities
Changes in short-term borrowings	(340)	(220)
Proceeds from short-term borrowings with maturities greater than 90 days	0	500
Issuance of long-term debt	151	2,403
Retirement of long-term debt	(56)	(2,936)
Changes in Exelon/PHI intercompany money pool	(285)	0
Distributions to member	(916)	(937)
Other financing activities	(29)	(30)
Net cash flows provided by (used in) financing activities	(1,475)	(1,220)
Increase (decrease) in cash, restricted cash, and cash equivalents	274	187
Cash, restricted cash, and cash equivalents at beginning of period	327	449
Cash, restricted cash, and cash equivalents at end of period	601	636
Supplemental Cash Flow Information
Increase (decrease) in capital expenditures not paid	(66)	(108)
Increase in deferred purchase price	1,958	1,754
Commonwealth Edison Co [Member]
Cash flows from operating activities
Net income (loss)	390	107
Adjustments to reconcile net income to net cash flows provided by operating activities:
Depreciation, amortization, and accretion, including nuclear fuel and energy contract amortization	589	547
Asset impairments	0	15
Deferred income taxes and amortization of investment tax credits	143	129
Other non-cash operating activities	23	283
Changes in assets and liabilities:
Accounts receivable	(48)	(92)
Receivables from and payables to affiliates, net	5	(6)
Inventories	(2)	(7)
Accounts payable and accrued expenses	(45)	4
Collateral received (posted), net	2	(3)
Income taxes	(34)	(90)
Pension and non-pension postretirement benefit contributions	(173)	(144)
Other assets and liabilities	(292)	(245)
Net cash flows provided by operating activities	558	498
Cash flows from investing activities
Capital expenditures	(1,162)	(1,029)
Other investing activities	12	(4)
Net cash flows provided by (used in) investing activities	(1,150)	(1,033)
Cash flows from financing activities
Changes in short-term borrowings	(290)	(130)
Issuance of long-term debt	700	1,000
Dividends paid on common stock	(253)	(249)
Contributions from parent	395	249
Other financing activities	(11)	(14)
Net cash flows provided by (used in) financing activities	541	856
Increase (decrease) in cash, restricted cash, and cash equivalents	(51)	321
Cash, restricted cash, and cash equivalents at beginning of period	405	403
Cash, restricted cash, and cash equivalents at end of period	354	724
Supplemental Cash Flow Information
Increase (decrease) in capital expenditures not paid	(93)	18
PECO Energy Co [Member]
Cash flows from operating activities
Net income (loss)	271	178
Adjustments to reconcile net income to net cash flows provided by operating activities:
Depreciation, amortization, and accretion, including nuclear fuel and energy contract amortization	173	173
Deferred income taxes and amortization of investment tax credits	21	6
Other non-cash operating activities	(5)	25
Changes in assets and liabilities:
Accounts receivable	86	22
Receivables from and payables to affiliates, net	2	3
Inventories	3	10
Accounts payable and accrued expenses	(46)	27
Income taxes	24	15
Pension and non-pension postretirement benefit contributions	(15)	(18)
Other assets and liabilities	(140)	(48)
Net cash flows provided by operating activities	374	393
Cash flows from investing activities
Capital expenditures	(577)	(512)
Changes in Exelon/PHI intercompany money pool	0	68
Other investing activities	4	3
Net cash flows provided by (used in) investing activities	(573)	(441)
Cash flows from financing activities
Issuance of long-term debt	375	350
Changes in Exelon/PHI intercompany money pool	(40)	0
Dividends paid on common stock	(169)	(170)
Contributions from parent	395	231
Other financing activities	(4)	(3)
Net cash flows provided by (used in) financing activities	557	408
Increase (decrease) in cash, restricted cash, and cash equivalents	358	360
Cash, restricted cash, and cash equivalents at beginning of period	26	27
Cash, restricted cash, and cash equivalents at end of period	384	387
Supplemental Cash Flow Information
Increase (decrease) in capital expenditures not paid	(16)	42
Baltimore Gas and Electric Company [Member]
Cash flows from operating activities
Net income (loss)	254	219
Adjustments to reconcile net income to net cash flows provided by operating activities:
Depreciation, amortization, and accretion, including nuclear fuel and energy contract amortization	293	272
Deferred income taxes and amortization of investment tax credits	11	22
Other non-cash operating activities	28	50
Changes in assets and liabilities:
Accounts receivable	73	19
Receivables from and payables to affiliates, net	(19)	(26)
Inventories	(9)	10
Accounts payable and accrued expenses	(51)	(15)
Collateral received (posted), net	2	0
Income taxes	(27)	26
Pension and non-pension postretirement benefit contributions	(71)	(68)
Other assets and liabilities	(96)	(5)
Net cash flows provided by operating activities	388	504
Cash flows from investing activities
Capital expenditures	(620)	(548)
Other investing activities	10	(4)
Net cash flows provided by (used in) investing activities	(610)	(552)
Cash flows from financing activities
Changes in short-term borrowings	0	(76)
Issuance of long-term debt	600	400
Dividends paid on common stock	(146)	(123)
Contributions from parent	0	26
Other financing activities	(6)	(8)
Net cash flows provided by (used in) financing activities	448	219
Increase (decrease) in cash, restricted cash, and cash equivalents	226	171
Cash, restricted cash, and cash equivalents at beginning of period	145	25
Cash, restricted cash, and cash equivalents at end of period	371	196
Supplemental Cash Flow Information
Increase (decrease) in capital expenditures not paid	(71)	(14)
Pepco Holdings LLC [Member]
Cash flows from operating activities
Net income (loss)	269	202
Adjustments to reconcile net income to net cash flows provided by operating activities:
Depreciation, amortization, and accretion, including nuclear fuel and energy contract amortization	404	385
Deferred income taxes and amortization of investment tax credits	10	(74)
Other non-cash operating activities	(50)	107
Changes in assets and liabilities:
Accounts receivable	(30)	(64)
Receivables from and payables to affiliates, net	(22)	(22)
Inventories	3	6
Accounts payable and accrued expenses	(35)	14
Income taxes	(1)	(30)
Pension and non-pension postretirement benefit contributions	(40)	(31)
Other assets and liabilities	(131)	(146)
Net cash flows provided by operating activities	377	347
Cash flows from investing activities
Capital expenditures	(889)	(686)
Other investing activities	(2)	2
Net cash flows provided by (used in) investing activities	(891)	(684)
Cash flows from financing activities
Changes in short-term borrowings	(36)	(189)
Issuance of long-term debt	625	373
Retirement of long-term debt	(249)	(35)
Changes in Exelon/PHI intercompany money pool	(12)	10
Distributions to member	(414)	(268)
Contributions from member	560	359
Other financing activities	(8)	(8)
Net cash flows provided by (used in) financing activities	466	242
Increase (decrease) in cash, restricted cash, and cash equivalents	(48)	(95)
Cash, restricted cash, and cash equivalents at beginning of period	160	181
Cash, restricted cash, and cash equivalents at end of period	112	86
Supplemental Cash Flow Information
Increase (decrease) in capital expenditures not paid	(41)	(24)
Potomac Electric Power Company [Member]
Cash flows from operating activities
Net income (loss)	134	109
Adjustments to reconcile net income to net cash flows provided by operating activities:
Depreciation, amortization, and accretion, including nuclear fuel and energy contract amortization	199	186
Deferred income taxes and amortization of investment tax credits	10	(22)
Other non-cash operating activities	(43)	11
Changes in assets and liabilities:
Accounts receivable	(23)	(45)
Receivables from and payables to affiliates, net	(11)	(22)
Inventories	1	3
Accounts payable and accrued expenses	(26)	11
Income taxes	(20)	(18)
Pension and non-pension postretirement benefit contributions	(7)	(6)
Other assets and liabilities	(79)	(52)
Net cash flows provided by operating activities	135	155
Cash flows from investing activities
Capital expenditures	(439)	(324)
Other investing activities	(2)	(3)
Net cash flows provided by (used in) investing activities	(441)	(327)
Cash flows from financing activities
Changes in short-term borrowings	119	(68)
Issuance of long-term debt	150	150
Retirement of long-term debt	0	(1)
Changes in Exelon/PHI intercompany money pool	9	50
Dividends paid on common stock	(123)	(101)
Contributions from parent	138	137
Other financing activities	(2)	(6)
Net cash flows provided by (used in) financing activities	291	161
Increase (decrease) in cash, restricted cash, and cash equivalents	(15)	(11)
Cash, restricted cash, and cash equivalents at beginning of period	65	63
Cash, restricted cash, and cash equivalents at end of period	50	52
Supplemental Cash Flow Information
Increase (decrease) in capital expenditures not paid	(15)	(28)
Delmarva Power and Light Company [Member]
Cash flows from operating activities
Net income (loss)	86	64
Adjustments to reconcile net income to net cash flows provided by operating activities:
Depreciation, amortization, and accretion, including nuclear fuel and energy contract amortization	104	94
Deferred income taxes and amortization of investment tax credits	4	(19)
Other non-cash operating activities	(12)	40
Changes in assets and liabilities:
Accounts receivable	24	6
Receivables from and payables to affiliates, net	(12)	(2)
Accounts payable and accrued expenses	7	3
Income taxes	14	(12)
Other assets and liabilities	(22)	(21)
Net cash flows provided by operating activities	193	153
Cash flows from investing activities
Capital expenditures	(211)	(184)
Changes in Exelon/PHI intercompany money pool	(9)	(55)
Other investing activities	1	(3)
Net cash flows provided by (used in) investing activities	(219)	(242)
Cash flows from financing activities
Changes in short-term borrowings	(146)	(56)
Issuance of long-term debt	125	100
Retirement of long-term debt	0	(1)
Dividends paid on common stock	(63)	(66)
Contributions from parent	120	106
Other financing activities	(3)	(1)
Net cash flows provided by (used in) financing activities	33	82
Increase (decrease) in cash, restricted cash, and cash equivalents	7	(7)
Cash, restricted cash, and cash equivalents at beginning of period	15	13
Cash, restricted cash, and cash equivalents at end of period	22	6
Supplemental Cash Flow Information
Increase (decrease) in capital expenditures not paid	(14)	(4)
Atlantic City Electric Company [Member]
Cash flows from operating activities
Net income (loss)	51	31
Adjustments to reconcile net income to net cash flows provided by operating activities:
Depreciation, amortization, and accretion, including nuclear fuel and energy contract amortization	87	86
Deferred income taxes and amortization of investment tax credits	(2)	(30)
Other non-cash operating activities	(14)	34
Changes in assets and liabilities:
Accounts receivable	(30)	(23)
Receivables from and payables to affiliates, net	4	9
Inventories	2	2
Accounts payable and accrued expenses	(2)	17
Income taxes	2	2
Pension and non-pension postretirement benefit contributions	(3)	(2)
Other assets and liabilities	(25)	(68)
Net cash flows provided by operating activities	70	58
Cash flows from investing activities
Capital expenditures	(239)	(178)
Other investing activities	0	5
Net cash flows provided by (used in) investing activities	(239)	(173)
Cash flows from financing activities
Changes in short-term borrowings	(9)	(65)
Issuance of long-term debt	350	123
Retirement of long-term debt	(249)	(34)
Changes in Exelon/PHI intercompany money pool	0	5
Dividends paid on common stock	(229)	(35)
Contributions from parent	303	116
Other financing activities	(4)	(1)
Net cash flows provided by (used in) financing activities	162	109
Increase (decrease) in cash, restricted cash, and cash equivalents	(7)	(6)
Cash, restricted cash, and cash equivalents at beginning of period	30	28
Cash, restricted cash, and cash equivalents at end of period	23	22
Supplemental Cash Flow Information
Increase (decrease) in capital expenditures not paid	$ (13)	$ 7

Consolidated Balance Sheets (Un

Consolidated Balance Sheets (Unaudited) - USD ($) shares in Millions, $ in Millions		Jun. 30, 2021	Dec. 31, 2020
Current Assets
Cash and cash equivalents		$ 1,578	$ 663
Restricted cash and cash equivalents		379	438
Accounts receivable
Customer accounts receivable		3,533	3,597
Customer allowance for credit losses		(395)	(366)
Customer accounts receivable, net		3,138	3,231
Other accounts receivable		1,426	1,469
Other allowance for credit losses		(72)	(71)
Other accounts receivable, net		1,354	1,398
Mark-to-market derivative assets, current		749	644
Unamortized energy contract assets, current		37	38
Inventories, net
Fossil fuel and emission allowances		259	297
Materials and supplies		1,443	1,425
Regulatory assets, current		1,252	1,228
Renewable energy credits, current		368	633
Assets held for sale		11	958
Other		1,780	1,609
Total current assets		12,348	12,562
Accumulated depreciation and amortization		28,783	26,727
Property, plant and equipment, net		82,120	82,584
Deferred debits and other assets
Regulatory assets, noncurrent		8,745	8,759
Nuclear decommissioning trust funds		15,400	14,464
Investments		421	440
Goodwill		6,677	6,677
Mark-to-market derivative assets, noncurrent		443	555
Unamortized energy contract assets, noncurrent		278	294
Other		2,964	2,982
Total deferred debits and other assets		34,928	34,171
Total assets	[1]	129,396	129,317
Current Liabilities
Short-term borrowings		1,865	2,031
Long-term debt due within one year		3,633	1,819
Accounts payable		3,547	3,562
Accrued expenses		1,719	2,078
Payables to affiliates, current		5	5
Regulatory liabilities, current		686	581
Mark-to-market derivative liabilities, current		719	295
Unamortized energy contract liabilities, current		95	100
Renewable energy credit obligation		509	661
Liabilities held for sale		2	375
Other		1,139	1,264
Total current liabilities		13,919	12,771
Long-term debt		35,077	35,093
Long-term debt to financing trusts		390	390
Deferred credits and other liabilities
Deferred income taxes and unamortized investment tax credits		13,194	13,035
Asset retirement obligations, noncurrent		12,502	12,300
Pension obligations		3,880	4,503
Non-pension postretirement benefit obligations		1,983	2,011
Spent nuclear fuel obligation		1,209	1,208
Regulatory liabilities, noncurrent		9,148	9,485
Mark-to-market derivative liabilities, noncurrent		554	473
Unamortized energy contract liabilities, noncurrent		192	238
Other		2,848	2,942
Total deferred credits and other liabilities		45,510	46,195
Total liabilities	[1]	94,896	94,449
Commitments and contingencies
Shareholders' equity
Common Stock, No Par Value		$ 0	$ 0
Common stock, shares authorized		2,000	2,000
Common stock, shares outstanding		978	976
Common stock		$ 19,454	$ 19,373
Treasury stock, shares		2	2
Treasury stock, at cost		$ (123)	$ (123)
Retained earnings/Undistributed earnings (losses)		16,098	16,735
Accumulated other comprehensive loss, net		(3,289)	(3,400)
Total shareholders’ equity		32,140	32,585
Member’s equity
Noncontrolling interests		2,360	2,283
Total equity		34,500	34,868
Total liabilities and shareholders’ equity		129,396	129,317
Variable Interest Entity, Primary Beneficiary [Member]
Current Assets
Cash and cash equivalents		233	98
Restricted cash and cash equivalents		57	47
Accounts receivable
Customer accounts receivable, net		169	148
Unamortized energy contract assets, current		22	22
Inventories, net
Materials and supplies		255	244
Assets held for sale		0	101
Other		408	674
Total current assets		1,188	1,370
Property, plant and equipment, net		5,656	5,803
Deferred debits and other assets
Nuclear decommissioning trust funds		3,215	3,007
Unamortized energy contract assets, noncurrent		237	249
Other		35	52
Total assets		10,331	10,481
Current Liabilities
Long-term debt due within one year		84	94
Accounts payable		67	81
Accrued expenses		56	70
Unamortized energy contract liabilities, current		1	4
Liabilities held for sale		0	16
Other		1	5
Total current liabilities		209	270
Long-term debt		860	889
Deferred credits and other liabilities
Asset retirement obligations, noncurrent		2,377	2,318
Other		133	129
Total liabilities		3,579	3,606
Variable Interest Entity, Primary Beneficiary [Member] \| Asset Pledged as Collateral [Member]
Deferred debits and other assets
Total assets		10,093	10,200
Variable Interest Entity, Primary Beneficiary [Member] \| Nonrecourse [Member]
Deferred credits and other liabilities
Total liabilities		3,578	3,598
Exelon Generation Co L L C [Member]
Current Assets
Cash and cash equivalents		542	226
Restricted cash and cash equivalents		59	89
Accounts receivable
Customer accounts receivable		1,410	1,330
Customer allowance for credit losses		(75)	(32)
Customer accounts receivable, net		1,335	1,298
Other accounts receivable		476	352
Other allowance for credit losses		(1)	0
Other accounts receivable, net		475	352
Mark-to-market derivative assets, current		749	644
Receivables from affiliates, current		117	153
Unamortized energy contract assets, current		37	38
Inventories, net
Fossil fuel and emission allowances		204	233
Materials and supplies		986	978
Renewable energy credits, current		341	621
Assets held for sale		11	958
Other		1,353	1,357
Total current assets		6,209	6,947
Accumulated depreciation and amortization		15,024	13,370
Property, plant and equipment, net		19,837	22,214
Deferred debits and other assets
Nuclear decommissioning trust funds		15,400	14,464
Investments		157	184
Goodwill		47	47
Mark-to-market derivative assets, noncurrent		441	555
Prepaid pension asset		1,713	1,558
Unamortized energy contract assets, noncurrent		278	293
Deferred income taxes		14	6
Other		1,725	1,826
Total deferred debits and other assets		19,775	18,933
Total assets	[2]	45,821	48,094
Current Liabilities
Short-term borrowings		500	840
Long-term debt due within one year		1,229	197
Accounts payable		1,489	1,253
Accrued expenses		654	788
Payables to affiliates, current		119	107
Borrowings from Exelon/PHI intercompany money pool		0	285
Mark-to-market derivative liabilities, current		695	262
Unamortized energy contract liabilities, current		4	7
Renewable energy credit obligation		508	661
Liabilities held for sale		2	375
Other		313	444
Total current liabilities		5,513	5,219
Long-term debt		4,627	5,566
Long-term debt to affiliates		322	324
Deferred credits and other liabilities
Deferred income taxes and unamortized investment tax credits		3,460	3,656
Asset retirement obligations, noncurrent		12,257	12,054
Non-pension postretirement benefit obligations		857	858
Spent nuclear fuel obligation		1,209	1,208
Payables to affiliates, noncurrent		3,011	3,017
Mark-to-market derivative liabilities, noncurrent		311	205
Unamortized energy contract liabilities, noncurrent		3	3
Other		1,266	1,308
Total deferred credits and other liabilities		22,374	22,309
Total liabilities	[2]	32,836	33,418
Commitments and contingencies
Shareholders' equity
Retained earnings/Undistributed earnings (losses)		1,035	2,805
Accumulated other comprehensive loss, net		(27)	(30)
Member’s equity
Membership interest		9,624	9,624
Total members' equity		10,632	12,399
Noncontrolling interests		2,353	2,277
Total equity		12,985	14,676
Total liabilities and shareholders’ equity		45,821	48,094
Exelon Generation Co L L C [Member] \| Variable Interest Entity, Primary Beneficiary [Member]
Current Assets
Cash and cash equivalents		233	98
Restricted cash and cash equivalents		54	44
Accounts receivable
Customer accounts receivable, net		169	148
Unamortized energy contract assets, current		22	22
Inventories, net
Materials and supplies		255	244
Assets held for sale		0	101
Other		404	669
Total current assets		1,181	1,362
Property, plant and equipment, net		5,656	5,803
Deferred debits and other assets
Nuclear decommissioning trust funds		3,215	3,007
Unamortized energy contract assets, noncurrent		237	249
Other		26	42
Total assets		10,315	10,463
Current Liabilities
Long-term debt due within one year		69	68
Accounts payable		67	81
Accrued expenses		56	70
Unamortized energy contract liabilities, current		1	4
Liabilities held for sale		0	16
Other		1	5
Total current liabilities		194	244
Long-term debt		860	889
Deferred credits and other liabilities
Asset retirement obligations, noncurrent		2,377	2,318
Other		133	129
Total liabilities		3,564	3,580
Exelon Generation Co L L C [Member] \| Variable Interest Entity, Primary Beneficiary [Member] \| Asset Pledged as Collateral [Member]
Deferred debits and other assets
Total assets		10,077	10,182
Exelon Generation Co L L C [Member] \| Variable Interest Entity, Primary Beneficiary [Member] \| Nonrecourse [Member]
Deferred credits and other liabilities
Total liabilities		3,563	3,572
Commonwealth Edison Co [Member]
Current Assets
Cash and cash equivalents		71	83
Restricted cash and cash equivalents		240	279
Accounts receivable
Customer accounts receivable		687	656
Customer allowance for credit losses		(89)	(97)
Customer accounts receivable, net		598	559
Other accounts receivable		257	239
Other allowance for credit losses		(18)	(21)
Other accounts receivable, net		239	218
Receivables from affiliates, current		22	22
Inventories, net
Inventories, net		170	170
Regulatory assets, current		298	279
Other		77	49
Total current assets		1,715	1,659
Accumulated depreciation and amortization		5,885	5,672
Property, plant and equipment, net		25,170	24,557
Deferred debits and other assets
Regulatory assets, noncurrent		1,846	1,749
Investments		6	6
Goodwill		2,625	2,625
Receivables from affiliates, noncurrent		2,439	2,541
Prepaid pension asset		1,138	1,022
Other		385	307
Total deferred debits and other assets		8,439	8,250
Total assets		35,324	34,466
Current Liabilities
Short-term borrowings		33	323
Long-term debt due within one year		350	350
Accounts payable		575	683
Accrued expenses		346	390
Payables to affiliates, current		102	96
Customer deposits		90	86
Regulatory liabilities, current		419	289
Mark-to-market derivative liabilities, current			33
Other		147	143
Total current liabilities		2,085	2,393
Long-term debt		9,325	8,633
Long-term debt to financing trusts		205	205
Deferred credits and other liabilities
Deferred income taxes and unamortized investment tax credits		4,531	4,341
Asset retirement obligations, noncurrent		128	126
Non-pension postretirement benefit obligations		180	173
Regulatory liabilities, noncurrent		6,181	6,403
Mark-to-market derivative liabilities, noncurrent			268
Other		587	595
Total deferred credits and other liabilities		11,849	11,906
Total liabilities		23,464	23,137
Commitments and contingencies
Shareholders' equity
Common stock		1,588	1,588
Other paid-in capital		8,680	8,285
Retained deficit unappropriated		(1,639)	(1,639)
Retained earnings appropriated		3,231	3,095
Total shareholders’ equity		11,860	11,329
Member’s equity
Total liabilities and shareholders’ equity		35,324	34,466
PECO Energy Co [Member]
Current Assets
Cash and cash equivalents		376	19
Restricted cash and cash equivalents		8	7
Accounts receivable
Customer accounts receivable		419	511
Customer allowance for credit losses		(111)	(116)
Customer accounts receivable, net		308	395
Other accounts receivable		106	130
Other allowance for credit losses		(7)	(8)
Other accounts receivable, net		99	122
Receivables from affiliates, current		0	2
Inventories, net
Fossil fuel and emission allowances		25	33
Materials and supplies		42	38
Prepaid utility taxes		76	0
Regulatory assets, current		30	25
Other		37	21
Total current assets		1,001	662
Accumulated depreciation and amortization		3,906	3,843
Property, plant and equipment, net		10,581	10,181
Deferred debits and other assets
Regulatory assets, noncurrent		866	776
Investments		32	30
Receivables from affiliates, noncurrent		571	475
Prepaid pension asset		387	375
Other		53	32
Total deferred debits and other assets		1,909	1,688
Total assets		13,491	12,531
Current Liabilities
Long-term debt due within one year		300	300
Accounts payable		436	479
Accrued expenses		125	129
Payables to affiliates, current		50	50
Borrowings from Exelon/PHI intercompany money pool		0	40
Customer deposits		50	59
Regulatory liabilities, current		109	121
Other		29	30
Total current liabilities		1,099	1,208
Long-term debt		3,825	3,453
Long-term debt to financing trusts		184	184
Deferred credits and other liabilities
Deferred income taxes and unamortized investment tax credits		2,345	2,242
Asset retirement obligations, noncurrent		29	29
Non-pension postretirement benefit obligations		287	286
Regulatory liabilities, noncurrent		600	503
Other		92	93
Total deferred credits and other liabilities		3,353	3,153
Total liabilities		8,461	7,998
Commitments and contingencies
Shareholders' equity
Common stock		3,409	3,014
Retained earnings/Undistributed earnings (losses)		1,621	1,519
Total shareholders’ equity		5,030	4,533
Member’s equity
Total liabilities and shareholders’ equity		13,491	12,531
Baltimore Gas and Electric Company [Member]
Current Assets
Cash and cash equivalents		368	144
Restricted cash and cash equivalents		3	1
Accounts receivable
Customer accounts receivable		398	487
Customer allowance for credit losses		(27)	(35)
Customer accounts receivable, net		371	452
Other accounts receivable		146	117
Other allowance for credit losses		(8)	(9)
Other accounts receivable, net		138	108
Receivables from affiliates, current		0	3
Inventories, net
Fossil fuel and emission allowances		27	25
Materials and supplies		48	41
Regulatory assets, current		177	168
Other		9	6
Total current assets		1,141	948
Accumulated depreciation and amortization		4,151	4,034
Property, plant and equipment, net		10,200	9,872
Deferred debits and other assets
Regulatory assets, noncurrent		473	481
Investments		13	10
Prepaid pension asset		302	270
Other		57	69
Total deferred debits and other assets		845	830
Total assets		12,186	11,650
Current Liabilities
Long-term debt due within one year		300	300
Accounts payable		287	346
Accrued expenses		138	205
Payables to affiliates, current		41	61
Customer deposits		101	110
Regulatory liabilities, current		32	30
Other		87	91
Total current liabilities		986	1,143
Long-term debt		3,959	3,364
Deferred credits and other liabilities
Deferred income taxes and unamortized investment tax credits		1,643	1,521
Asset retirement obligations, noncurrent		24	23
Non-pension postretirement benefit obligations		179	189
Regulatory liabilities, noncurrent		998	1,109
Other		92	104
Total deferred credits and other liabilities		2,936	2,946
Total liabilities		7,881	7,453
Commitments and contingencies
Shareholders' equity
Common stock		2,318	2,318
Retained earnings/Undistributed earnings (losses)		1,987	1,879
Total shareholders’ equity		4,305	4,197
Member’s equity
Total liabilities and shareholders’ equity		12,186	11,650
Pepco Holdings LLC [Member]
Current Assets
Cash and cash equivalents		61	111
Restricted cash and cash equivalents		42	39
Accounts receivable
Customer accounts receivable		617	611
Customer allowance for credit losses		(93)	(86)
Customer accounts receivable, net		524	525
Other accounts receivable		286	260
Other allowance for credit losses		(38)	(33)
Other accounts receivable, net		248	227
Receivables from affiliates, current		1	8
Inventories, net
Fossil fuel and emission allowances		5	6
Materials and supplies		196	198
Regulatory assets, current		431	440
Other		77	45
Total current assets		1,585	1,599
Accumulated depreciation and amortization		1,827	1,811
Property, plant and equipment, net		15,927	15,377
Deferred debits and other assets
Regulatory assets, noncurrent		1,898	1,933
Investments		145	140
Goodwill		4,005	4,005
Prepaid pension asset		370	365
Deferred income taxes		10	10
Other		295	307
Total deferred debits and other assets		6,723	6,760
Total assets	[3]	24,235	23,736
Current Liabilities
Short-term borrowings		332	368
Long-term debt due within one year		300	347
Accounts payable		517	539
Accrued expenses		246	299
Payables to affiliates, current		75	104
Borrowings from Exelon/PHI intercompany money pool		9	21
Customer deposits		89	106
Regulatory liabilities, current		123	137
Unamortized energy contract liabilities, current		92	92
Other		131	141
Total current liabilities		1,914	2,154
Long-term debt		7,069	6,659
Deferred credits and other liabilities
Deferred income taxes and unamortized investment tax credits		2,541	2,439
Asset retirement obligations, noncurrent		59	59
Non-pension postretirement benefit obligations		75	86
Regulatory liabilities, noncurrent		1,338	1,438
Unamortized energy contract liabilities, noncurrent		190	235
Other		590	622
Total deferred credits and other liabilities		4,793	4,879
Total liabilities	[3]	13,776	13,692
Commitments and contingencies
Shareholders' equity
Retained earnings/Undistributed earnings (losses)		(213)	(68)
Member’s equity
Membership interest		10,672	10,112
Total members' equity		10,459	10,044
Total equity		10,459	10,044
Total liabilities and shareholders’ equity		24,235	23,736
Pepco Holdings LLC [Member] \| Variable Interest Entity, Primary Beneficiary [Member]
Current Assets
Cash and cash equivalents		0	0
Restricted cash and cash equivalents		3	3
Accounts receivable
Customer accounts receivable, net		0	0
Unamortized energy contract assets, current		0	0
Inventories, net
Materials and supplies		0	0
Assets held for sale		0	0
Other		4	5
Total current assets		7	8
Property, plant and equipment, net		0	0
Deferred debits and other assets
Nuclear decommissioning trust funds		0	0
Unamortized energy contract assets, noncurrent		0	0
Other		9	10
Total assets		16	18
Current Liabilities
Long-term debt due within one year		15	26
Accounts payable		0	0
Accrued expenses		0	0
Unamortized energy contract liabilities, current		0	0
Liabilities held for sale		0	0
Other		0	0
Total current liabilities		15	26
Long-term debt		0	0
Deferred credits and other liabilities
Asset retirement obligations, noncurrent		0	0
Other		0	0
Total liabilities		15	26
Pepco Holdings LLC [Member] \| Variable Interest Entity, Primary Beneficiary [Member] \| Asset Pledged as Collateral [Member]
Deferred debits and other assets
Total assets		16	18
Pepco Holdings LLC [Member] \| Variable Interest Entity, Primary Beneficiary [Member] \| Nonrecourse [Member]
Deferred credits and other liabilities
Total liabilities		15	26
Potomac Electric Power Company [Member]
Current Assets
Cash and cash equivalents		17	30
Restricted cash and cash equivalents		33	35
Accounts receivable
Customer accounts receivable		290	279
Customer allowance for credit losses		(38)	(32)
Customer accounts receivable, net		252	247
Other accounts receivable		155	131
Other allowance for credit losses		(16)	(13)
Other accounts receivable, net		139	118
Receivables from affiliates, current		0	2
Inventories, net
Inventories, net		110	111
Regulatory assets, current		215	214
Other		13	13
Total current assets		779	770
Accumulated depreciation and amortization		3,782	3,697
Property, plant and equipment, net		7,771	7,456
Deferred debits and other assets
Regulatory assets, noncurrent		571	570
Investments		118	115
Prepaid pension asset		282	284
Other		67	69
Total deferred debits and other assets		1,038	1,038
Total assets		9,588	9,264
Current Liabilities
Short-term borrowings		154	35
Long-term debt due within one year		204	3
Accounts payable		215	226
Accrued expenses		123	164
Payables to affiliates, current		42	55
Borrowings from Exelon/PHI intercompany money pool		9	0
Customer deposits		41	51
Regulatory liabilities, current		38	46
Merger related obligation		29	33
Current portion of DC PLUG obligation		30	30
Other		29	31
Total current liabilities		914	674
Long-term debt		3,114	3,162
Deferred credits and other liabilities
Deferred income taxes and unamortized investment tax credits		1,244	1,189
Asset retirement obligations, noncurrent		39	39
Non-pension postretirement benefit obligations		7	13
Regulatory liabilities, noncurrent		599	644
Other		319	340
Total deferred credits and other liabilities		2,208	2,225
Total liabilities		6,236	6,061
Commitments and contingencies
Shareholders' equity
Common stock		2,196	2,058
Retained earnings/Undistributed earnings (losses)		1,156	1,145
Total shareholders’ equity		3,352	3,203
Member’s equity
Total liabilities and shareholders’ equity		9,588	9,264
Delmarva Power and Light Company [Member]
Current Assets
Cash and cash equivalents		17	15
Restricted cash and cash equivalents		5	0
Accounts receivable
Customer accounts receivable		139	176
Customer allowance for credit losses		(19)	(22)
Customer accounts receivable, net		120	154
Other accounts receivable		62	68
Other allowance for credit losses		(9)	(9)
Other accounts receivable, net		53	59
Receivables from affiliates, current		0	1
Receivable from Exelon/PHI intercompany money pool		9	0
Inventories, net
Fossil fuel and emission allowances		5	6
Materials and supplies		52	51
Prepaid utility taxes		0	11
Regulatory assets, current		70	58
Renewable energy credits, current		18	10
Other		3	3
Total current assets		352	368
Accumulated depreciation and amortization		1,571	1,533
Property, plant and equipment, net		4,425	4,314
Deferred debits and other assets
Regulatory assets, noncurrent		223	222
Goodwill		8	8
Prepaid pension asset		159	162
Other		62	66
Total deferred debits and other assets		452	458
Total assets		5,229	5,140
Current Liabilities
Short-term borrowings		0	146
Long-term debt due within one year		82	82
Accounts payable		125	126
Accrued expenses		40	46
Payables to affiliates, current		23	36
Customer deposits		28	32
Regulatory liabilities, current		46	47
Other		14	20
Total current liabilities		358	535
Long-term debt		1,722	1,595
Deferred credits and other liabilities
Deferred income taxes and unamortized investment tax credits		745	715
Asset retirement obligations, noncurrent		14	14
Non-pension postretirement benefit obligations		13	15
Regulatory liabilities, noncurrent		462	493
Other		96	97
Total deferred credits and other liabilities		1,330	1,334
Total liabilities		3,410	3,464
Commitments and contingencies
Shareholders' equity
Common stock		1,209	1,089
Retained earnings/Undistributed earnings (losses)		610	587
Total shareholders’ equity		1,819	1,676
Member’s equity
Total liabilities and shareholders’ equity		5,229	5,140
Atlantic City Electric Company [Member]
Current Assets
Cash and cash equivalents		11	17
Restricted cash and cash equivalents		3	3
Accounts receivable
Customer accounts receivable		188	156
Customer allowance for credit losses		(36)	(32)
Customer accounts receivable, net		152	124
Other accounts receivable		69	72
Other allowance for credit losses		(13)	(11)
Other accounts receivable, net		56	61
Receivables from affiliates, current		1	6
Inventories, net
Inventories, net		35	37
Prepaid utility taxes		37	0
Regulatory assets, current		53	75
Other		5	3
Total current assets		353	326
Accumulated depreciation and amortization		1,358	1,303
Property, plant and equipment, net		3,614	3,475
Deferred debits and other assets
Regulatory assets, noncurrent		422	395
Prepaid pension asset		35	40
Other		49	50
Total deferred debits and other assets		506	485
Total assets	[4]	4,473	4,286
Current Liabilities
Short-term borrowings		178	187
Long-term debt due within one year		13	261
Accounts payable		170	177
Accrued expenses		38	46
Payables to affiliates, current		30	31
Customer deposits		20	23
Regulatory liabilities, current		39	44
Other		11	11
Total current liabilities		499	780
Long-term debt		1,502	1,152
Deferred credits and other liabilities
Deferred income taxes and unamortized investment tax credits		643	624
Non-pension postretirement benefit obligations		14	17
Regulatory liabilities, noncurrent		252	274
Other		47	48
Total deferred credits and other liabilities		956	963
Total liabilities	[4]	2,957	2,895
Commitments and contingencies
Shareholders' equity
Common stock		1,574	1,271
Retained earnings/Undistributed earnings (losses)		(58)	120
Total shareholders’ equity		1,516	1,391
Member’s equity
Total liabilities and shareholders’ equity		4,473	4,286
Atlantic City Electric Company [Member] \| Variable Interest Entity, Primary Beneficiary [Member]
Current Assets
Cash and cash equivalents		0	0
Restricted cash and cash equivalents		3	3
Accounts receivable
Customer accounts receivable, net		0	0
Unamortized energy contract assets, current		0	0
Inventories, net
Materials and supplies		0	0
Assets held for sale		0	0
Other		0	0
Total current assets		3	3
Property, plant and equipment, net		0	0
Deferred debits and other assets
Nuclear decommissioning trust funds		0	0
Unamortized energy contract assets, noncurrent		0	0
Other		9	10
Total assets		12
Current Liabilities
Long-term debt due within one year		11	21
Accounts payable		0	0
Accrued expenses		0	0
Unamortized energy contract liabilities, current		0	0
Liabilities held for sale		0	0
Other		0	0
Total current liabilities		11	21
Long-term debt		0	0
Deferred credits and other liabilities
Asset retirement obligations, noncurrent		0	0
Other		0	0
Total liabilities		11	21
Atlantic City Electric Company [Member] \| Variable Interest Entity, Primary Beneficiary [Member] \| Asset Pledged as Collateral [Member]
Deferred debits and other assets
Total assets		12	13
Atlantic City Electric Company [Member] \| Variable Interest Entity, Primary Beneficiary [Member] \| Nonrecourse [Member]
Deferred credits and other liabilities
Total liabilities		$ 11	$ 21

[1]	Exelon’s consolidated assets include $10,093 million and $10,200 million at June 30, 2021 and December 31, 2020, respectively, of certain VIEs that can only be used to settle the liabilities of the VIE. Exelon’s consolidated liabilities include $3,578 million and $3,598 million at June 30, 2021 and December 31, 2020, respectively, of certain VIEs for which the VIE creditors do not have recourse to Exelon. See Note 17 — Variable Interest Entities for additional information.
[2]	Generation’s consolidated assets include $10,077 million and $10,182 million at June 30, 2021 and December 31, 2020, respectively, of certain VIEs that can only be used to settle the liabilities of the VIE. Generation’s consolidated liabilities include $3,563 million and $3,572 million at June 30, 2021 and December 31, 2020, respectively, of certain VIEs for which the VIE creditors do not have recourse to Generation. See Note 17 — Variable Interest Entities for additional information.
[3]	PHI’s consolidated total assets include $16 million and $18 million at June 30, 2021 and December 31, 2020, respectively, of PHI's consolidated VIE that can only be used to settle the liabilities of the VIE. PHI’s consolidated total liabilities include $15 million and $26 million at June 30, 2021 and December 31, 2020, respectively, of PHI's consolidated VIE for which the VIE creditors do not have recourse to PHI. See Note 17 — Variable Interest Entities for additional information.
[4]	ACE’s consolidated total assets include $12 million and $13 million at June 30, 2021 and December 31, 2020, respectively, of ACE's consolidated VIE that can only be used to settle the liabilities of the VIE. ACE’s consolidated total liabilities include $11 million and $21 million at June 30, 2021 and December 31, 2020, respectively, of ACE's consolidated VIE for which the VIE creditors do not have recourse to ACE. See Note 17 — Variable Interest Entities for additional information.

Consolidated Statements of Chan

Consolidated Statements of Changes in Shareholders Equity (Unaudited) - USD ($) shares in Thousands, $ in Millions	Total	Correcting Adjustment [Member]	Common Stock [Member]	Common Stock [Member]Correcting Adjustment [Member]	Treasury Stock [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Noncontrolling Interest [Member]	Exelon Generation Co L L C [Member]	Exelon Generation Co L L C [Member]Retained Earnings [Member]	Exelon Generation Co L L C [Member]Accumulated Other Comprehensive Income (Loss) [Member]	Exelon Generation Co L L C [Member]Noncontrolling Interest [Member]	Exelon Generation Co L L C [Member]Membership Interest [Member]	Commonwealth Edison Co [Member]	Commonwealth Edison Co [Member]Common Stock [Member]	Commonwealth Edison Co [Member]Retained Earnings [Member]	Commonwealth Edison Co [Member]Other Paid-in-Capital [Member]	Commonwealth Edison Co [Member]Retained Earnings, Unappropriated [Member]	Commonwealth Edison Co [Member]Retained Earnings, Appropriated	PECO Energy Co [Member]	PECO Energy Co [Member]Common Stock [Member]	PECO Energy Co [Member]Retained Earnings [Member]	Baltimore Gas and Electric Company [Member]	Baltimore Gas and Electric Company [Member]Common Stock [Member]	Baltimore Gas and Electric Company [Member]Retained Earnings [Member]	Pepco Holdings LLC [Member]	Pepco Holdings LLC [Member]Retained Earnings [Member]	Pepco Holdings LLC [Member]Membership Interest [Member]	Potomac Electric Power Company [Member]	Potomac Electric Power Company [Member]Common Stock [Member]	Potomac Electric Power Company [Member]Retained Earnings [Member]	Delmarva Power and Light Company [Member]	Delmarva Power and Light Company [Member]Common Stock [Member]	Delmarva Power and Light Company [Member]Retained Earnings [Member]	Atlantic City Electric Company [Member]	Atlantic City Electric Company [Member]Common Stock [Member]	Atlantic City Electric Company [Member]Retained Earnings [Member]
Beginning balance (in shares) at Dec. 31, 2019	974,416
Beginning balance at Dec. 31, 2019	$ 34,573		$ 19,274		$ (123)	$ 16,267	$ (3,194)	$ 2,349
Beginning Balance at Dec. 31, 2019									$ 15,830	$ 3,950	$ (32)	$ 2,346	$ 9,566													$ 9,608	$ (10)	$ 9,618
Beginning Balance at Dec. 31, 2019														$ 10,677	$ 1,588		$ 7,572	$ (1,639)	$ 3,156	$ 4,178	$ 2,766	$ 1,412	$ 3,683	$ 1,907	$ 1,776				$ 2,907	$ 1,796	$ 1,111	$ 1,580	$ 977	$ 603	$ 1,276	$ 1,154	$ 122
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	$ 376					582		(206)	(161)	45		(206)		168				168		140		140	181		181	108	108		52		52	45		45	13		13
Appropriation of retained earnings for future dividends																$ 0		(168)	168
Long -Term Incentive Plan Activity (shares)	1,354
Long-Term Incentive Plan Activity		$ (4)		$ (4)
Employee stock purchase plan issuances (shares)	470
Employee stock purchase plan issuances	$ 31		31
Changes in equity of noncontrolling interests	(9)							(9)	(11)			(11)
Sale of noncontrolling interests	2		2						2				2
Common stock dividends	(374)					(374)								(125)					(125)	(85)		(85)	(62)		(62)				(28)		(28)	(52)		(52)	(23)		(23)
Distributions to member									(468)	(468)																(134)	(134)
Contributions from parent														125			125			231	231					144		144	137	137		6	6		1	1
Other comprehensive income (loss), net of income taxes	$ 21						21		(9)	0	(9)	0
Ending balance (in shares) at Mar. 31, 2020	976,240
Ending balance at Mar. 31, 2020	$ 34,616		19,303		(123)	16,475	(3,173)	2,134
Ending Balance at Mar. 31, 2020									15,183	3,527	(41)	2,129	9,568													9,726	(36)	9,762
Ending Balance at Mar. 31, 2020														10,845	1,588		7,697	(1,639)	3,199	4,464	2,997	1,467	3,802	1,907	1,895				3,068	1,933	1,135	1,579	983	596	1,267	1,155	112
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common Stock, Dividends, Per Share, Declared	$ 0.38
Beginning balance (in shares) at Dec. 31, 2019	974,416
Beginning balance at Dec. 31, 2019	$ 34,573		19,274		(123)	16,267	(3,194)	2,349
Beginning Balance at Dec. 31, 2019									15,830	3,950	(32)	2,346	9,566													9,608	(10)	9,618
Beginning Balance at Dec. 31, 2019														10,677	1,588		7,572	(1,639)	3,156	4,178	2,766	1,412	3,683	1,907	1,776				2,907	1,796	1,111	1,580	977	603	1,276	1,154	122
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	950								368					107						178			219			202			109			64			31
Other comprehensive income (loss), net of income taxes	$ 62						62		(7)
Ending balance (in shares) at Jun. 30, 2020	976,337
Ending balance at Jun. 30, 2020	$ 34,871		19,336		(123)	16,622	(3,132)	2,168
Ending Balance at Jun. 30, 2020									15,227	3,534	(39)	2,163	9,569													9,901	(76)	9,977
Ending Balance at Jun. 30, 2020														10,784	1,588		7,821	(1,700)	3,075	4,418	2,997	1,421	3,805	1,933	1,872				3,052	1,933	1,119	1,684	1,083	601	1,388	1,270	118
Beginning balance (in shares) at Mar. 31, 2020	976,240
Beginning balance at Mar. 31, 2020	$ 34,616		19,303		(123)	16,475	(3,173)	2,134
Beginning Balance at Mar. 31, 2020									15,183	3,527	(41)	2,129	9,568													9,726	(36)	9,762
Beginning Balance at Mar. 31, 2020														10,845	1,588		7,697	(1,639)	3,199	4,464	2,997	1,467	3,802	1,907	1,895				3,068	1,933	1,135	1,579	983	596	1,267	1,155	112
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	$ 574					521		53	529	476		53		(61)				(61)		39		39	39		39	94	94		57		57	19		19	18		18
Long -Term Incentive Plan Activity (shares)	148
Long-Term Incentive Plan Activity	$ 17		17
Employee stock purchase plan issuances (shares)		(51)
Employee stock purchase plan issuances	15		15
Changes in equity of noncontrolling interests	(19)							(19)	(19)			(19)
Sale of noncontrolling interests	1		1						1				1
Common stock dividends	(374)					(374)								(124)					(124)	(85)		(85)	(62)		(62)				(73)		(73)	(14)		(14)	(12)		(12)
Distributions to member									(469)	(469)																(134)	(134)
Contributions from parent														124			124						26	26		215		215				100	100		115	115
Other comprehensive income (loss), net of income taxes	$ 41						41		2	0	2	0
Ending balance (in shares) at Jun. 30, 2020	976,337
Ending balance at Jun. 30, 2020	$ 34,871		19,336		(123)	16,622	(3,132)	2,168
Ending Balance at Jun. 30, 2020									15,227	3,534	(39)	2,163	9,569													9,901	(76)	9,977
Ending Balance at Jun. 30, 2020														10,784	1,588		7,821	(1,700)	3,075	4,418	2,997	1,421	3,805	1,933	1,872				3,052	1,933	1,119	1,684	1,083	601	1,388	1,270	118
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common Stock, Dividends, Per Share, Declared	$ 0.38
Appropriation of retained earnings for future dividends														3,095
Beginning balance (in shares) at Dec. 31, 2020	977,466
Beginning balance at Dec. 31, 2020	$ 34,868		19,373		(123)	16,735	(3,400)	2,283
Beginning Balance at Dec. 31, 2020									14,676	2,805	(30)	2,277	9,624													10,044	(68)	10,112
Beginning Balance at Dec. 31, 2020	32,585													11,329	1,588		8,285	(1,639)	3,095	4,533	3,014	1,519	4,197	2,318	1,879				3,203	2,058	1,145	1,676	1,089	587	1,391	1,271	120
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	$ (264)					(289)		25	(769)	(793)		24		197				197		167		167	209		209	128	128		59		59	56		56	14		14
Appropriation of retained earnings for future dividends																0		(197)	197
Long -Term Incentive Plan Activity (shares)	640
Long-Term Incentive Plan Activity	$ 5		5
Employee stock purchase plan issuances (shares)	902
Employee stock purchase plan issuances	$ 34		34
Changes in equity of noncontrolling interests	(10)							(10)	(10)			(10)
Common stock dividends	(374)					(374)								(127)					(127)	(85)		(85)	(74)		(74)				(28)		(28)	(40)		(40)	(14)		(14)
Distributions to member									(458)	(458)																(81)	(81)
Contributions from parent														198			198									560		560	138	138		120	120		303	303
Other comprehensive income (loss), net of income taxes	$ 54						54		1	0	1	0
Ending balance (in shares) at Mar. 31, 2021	979,008
Ending balance at Mar. 31, 2021	$ 34,313		19,412		(123)	16,072	(3,346)	2,298
Ending Balance at Mar. 31, 2021									13,440	1,554	(29)	2,291	9,624													10,651	(21)	10,672
Ending Balance at Mar. 31, 2021														11,597	1,588		8,483	(1,639)	3,165	4,615	3,014	1,601	4,332	2,318	2,014				3,372	2,196	1,176	1,812	1,209	603	1,694	1,574	120
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common Stock, Dividends, Per Share, Declared	$ 0.38
Beginning balance (in shares) at Dec. 31, 2020	977,466
Beginning balance at Dec. 31, 2020	$ 34,868		19,373		(123)	16,735	(3,400)	2,283
Beginning Balance at Dec. 31, 2020									14,676	2,805	(30)	2,277	9,624													10,044	(68)	10,112
Beginning Balance at Dec. 31, 2020	32,585													11,329	1,588		8,285	(1,639)	3,095	4,533	3,014	1,519	4,197	2,318	1,879				3,203	2,058	1,145	1,676	1,089	587	1,391	1,271	120
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	211								(756)					390						271			254			269			134			86			51
Other comprehensive income (loss), net of income taxes	$ 111						111		3
Ending balance (in shares) at Jun. 30, 2021	979,665
Ending balance at Jun. 30, 2021	$ 34,500		19,454		(123)	16,098	(3,289)	2,360
Ending Balance at Jun. 30, 2021									12,985	1,035	(27)	2,353	9,624													10,459	(213)	10,672
Ending Balance at Jun. 30, 2021	$ 32,140													11,860	1,588		8,680	(1,639)	3,231	5,030	3,409	1,621	4,305	2,318	1,987				3,352	2,196	1,156	1,819	1,209	610	1,516	1,574	(58)
Beginning balance (in shares) at Mar. 31, 2021	979,008
Beginning balance at Mar. 31, 2021	$ 34,313		19,412		(123)	16,072	(3,346)	2,298
Beginning Balance at Mar. 31, 2021									13,440	1,554	(29)	2,291	9,624													10,651	(21)	10,672
Beginning Balance at Mar. 31, 2021														11,597	1,588		8,483	(1,639)	3,165	4,615	3,014	1,601	4,332	2,318	2,014				3,372	2,196	1,176	1,812	1,209	603	1,694	1,574	120
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	$ 476					401		75	13	(61)		74		192				192		104		104	45		45	141	141		75		75	30		30	37		37
Appropriation of retained earnings for future dividends																$ 0		(192)	192
Long -Term Incentive Plan Activity (shares)	237
Long-Term Incentive Plan Activity	$ 24		24
Employee stock purchase plan issuances (shares)	420
Employee stock purchase plan issuances	$ 18		18
Changes in equity of noncontrolling interests	(13)							(13)	(12)			(12)
Common stock dividends	(375)					(375)								(126)					(126)	(84)		(84)	(72)		(72)				(95)		(95)	(23)		(23)	(215)		(215)
Distributions to member									(458)	(458)																(333)	(333)
Contributions from parent														197			197			395	395
Other comprehensive income (loss), net of income taxes	$ 57						57		2	0	2	0
Ending balance (in shares) at Jun. 30, 2021	979,665
Ending balance at Jun. 30, 2021	$ 34,500		$ 19,454		$ (123)	$ 16,098	$ (3,289)	$ 2,360
Ending Balance at Jun. 30, 2021									$ 12,985	$ 1,035	$ (27)	$ 2,353	$ 9,624													$ 10,459	$ (213)	$ 10,672
Ending Balance at Jun. 30, 2021	$ 32,140													11,860	$ 1,588		$ 8,680	$ (1,639)	$ 3,231	$ 5,030	$ 3,409	$ 1,621	$ 4,305	$ 2,318	$ 1,987				$ 3,352	$ 2,196	$ 1,156	$ 1,819	$ 1,209	$ 610	$ 1,516	$ 1,574	$ (58)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common Stock, Dividends, Per Share, Declared	$ 0.38
Appropriation of retained earnings for future dividends														$ 3,231

Significant Accounting Policies

Significant Accounting Policies (All Registrants)	6 Months Ended
Significant Accounting Policies (All Registrants)	Jun. 30, 2021
Accounting Policies [Abstract]
Basis of Presentation and Significant Accounting Policies [Text Block]	Significant Accounting Policies (All Registrants) Description of Business (All Registrants) Exelon is a utility services holding company engaged in the generation, delivery and marketing of energy through Generation and the energy distribution and transmission businesses through ComEd, PECO, BGE, Pepco, DPL, and ACE. Name of Registrant Business Service Territories Exelon Generation Generation, physical delivery and marketing of power across multiple geographical regions through its customer-facing business, Constellation, which sells electricity to both wholesale and retail customers. Generation also sells natural gas, renewable energy, and other energy-related products and services. Five reportable segments: Mid-Atlantic, Midwest, New York, ERCOT, and Other Power Regions Commonwealth Edison Company Purchase and regulated retail sale of electricity Northern Illinois, including the City of Chicago Transmission and distribution of electricity to retail customers PECO Energy Company Purchase and regulated retail sale of electricity and natural gas Southeastern Pennsylvania, including the City of Philadelphia (electricity) Transmission and distribution of electricity and distribution of natural gas to retail customers Pennsylvania counties surrounding the City of Philadelphia (natural gas) Baltimore Gas and Electric Company Purchase and regulated retail sale of electricity and natural gas Central Maryland, including the City of Baltimore (electricity and natural gas) Transmission and distribution of electricity and distribution of natural gas to retail customers Pepco Holdings LLC Utility services holding company engaged, through its reportable segments Pepco, DPL, and ACE Service Territories of Pepco, DPL, and ACE Potomac Electric Purchase and regulated retail sale of electricity District of Columbia, and major portions of Montgomery and Prince George’s Counties, Maryland Transmission and distribution of electricity to retail customers Delmarva Power & Purchase and regulated retail sale of electricity and natural gas Portions of Delaware and Maryland (electricity) Transmission and distribution of electricity and distribution of natural gas to retail customers Portions of New Castle County, Delaware (natural gas) Atlantic City Electric Company Purchase and regulated retail sale of electricity Portions of Southern New Jersey Transmission and distribution of electricity to retail customers Basis of Presentation (All Registrants) This is a combined quarterly report of all Registrants. The Notes to the Consolidated Financial Statements apply to the Registrants as indicated parenthetically next to each corresponding disclosure. When appropriate, the Registrants are named specifically for their related activities and disclosures. Each of the Registrant’s Consolidated Financial Statements includes the accounts of its subsidiaries. All intercompany transactions have been eliminated. Through its business services subsidiary, BSC, Exelon provides its subsidiaries with a variety of support services at cost, including legal, human resources, financial, information technology, and supply management services. PHI also has a business services subsidiary, PHISCO, which provides a variety of support services at cost, including legal, accounting, engineering, customer operations, distribution and transmission planning, asset management, system operations, and power procurement, to PHI operating companies. The costs of BSC and PHISCO are directly charged or allocated to the applicable subsidiaries. The results of Exelon’s corporate operations are presented as “Other” within the consolidated financial statements and include intercompany eliminations unless otherwise disclosed. The accompanying consolidated financial statements as of June 30, 2021 and for the three and six months ended June 30, 2021 and 2020 are unaudited but, in the opinion of the management of each Registrant include all adjustments that are considered necessary for a fair statement of the Registrants’ respective financial statements in accordance with GAAP. All adjustments are of a normal, recurring nature, except as otherwise

Mergers, Acquisitions, and Disp

Mergers, Acquisitions, and Dispositions (Exelon and Generation)	6 Months Ended
	Jun. 30, 2021
Mergers, Acquisitions, and Dispositions [Abstract]
Mergers, Acquisitions, and Dispositions (Exelon and Generation)	Mergers, Acquisitions, and Dispositions (Exelon and Generation) CENG Put Option (Exelon and Generation) Generation owns a 50.01% membership interest in CENG, a joint venture with EDF, which wholly owns the Calvert Cliffs and Ginna nuclear stations and Nine Mile Point Unit 1, in addition to an 82% undivided ownership interest in Nine Mile Point Unit 2. CENG is 100% consolidated in Exelon's and Generation's financial statements. See Note 17 — Variable Interest Entities for additional information. On April 1, 2014, Generation and EDF entered into various agreements including a NOSA, an amended LLC Operating Agreement, an Employee Matters Agreement, and a Put Option Agreement, among others. Under the amended LLC Operating Agreement, CENG made a $400 million special distribution to EDF and committed to make preferred distributions to Generation until Generation has received aggregate distributions of $400 million plus a return of 8.50% per annum. Under the terms of the Put Option Agreement, EDF has the option to sell its 49.99% equity interest in CENG to Generation exercisable beginning on January 1, 2016 and thereafter until June 30, 2022. The Put Option Agreement’s terms also provide that in the event the put closing has not been completed prior to the 18-month anniversary of the exercise date, EDF may withdraw its exercise notice. In the event of a withdrawal, EDF retains the right to exercise the put option until the later of June 30, 2022 and 18 months following the date of withdrawal, but in no event later than January 1, 2024. EDF is not entitled to this withdrawal right in the event it breaches any provision of the Put Option Agreement that results in the failure of the put to close on or before the 18-month anniversary of the exercise date. The Put Option Agreement provides that the purchase price is to be determined by agreement of the parties, or absent such agreement, by a third-party arbitration process. The third parties determining fair market value of EDF’s 49.99% interest are to take into consideration all rights and obligations under the LLC Operating Agreement and Employee Matters Agreement including but not limited to Generation’s rights with respect to any unpaid aggregate preferred distributions and the related return. As of June 30, 2021, the total unpaid aggregate preferred distributions and related return owed to Generation is $645 million. On November 20, 2019, Generation received notice of EDF’s intention to exercise the put option to sell its interest in CENG to Generation, and the put automatically exercised on January 19, 2020 at the end of the sixty-day advance notice period. At this time, Generation cannot reasonably predict the ultimate purchase price that will be paid to EDF for its interest in CENG. The transaction required approval by the FERC and the NYPSC, which approvals were received on July 30, 2020 and April 15, 2021, respectively. The sale process is currently expected to close in the second half of 2021. EDF has not exercised its right to withdraw the exercise of the put, which right became effective on July 19, 2021. Agreement for Sale of Generation’s Solar Business (Exelon and Generation) On December 8, 2020, Generation entered into an agreement with an affiliate of Brookfield Renewable, for the sale of a significant portion of Generation’s solar business, including 360 MW of generation in operation or under construction across more than 600 sites across the United States. Generation will retain certain solar assets not included in this agreement, primarily Antelope Valley. Completion of the transaction contemplated by the sale agreement was subject to the satisfaction of several closing conditions which were satisfied in the first quarter of 2021. The sale was completed on March 31, 2021 for a purchase price of $810 million. Generation received cash proceeds of $675 million, net of $125 million long-term debt assumed by the buyer and certain working capital and other post-closing adjustments. Exelon and Generation recognized a pre-tax gain of $68 million which is included in Gain on sales of assets and businesses in Exelon’s and Generation’s Consolidated Statements of Operations and Comprehensive Income. See Note 17 — Debt and Credit Agreements of the Exelon 2020 Form 10-K for additional information on the SolGen nonrecourse debt included as part of the transaction. Agreement for the Sale of a Generation Biomass Facility (Exelon and Generation) On April 28, 2021, Generation and ReGenerate Energy Holdings, LLC (“ReGenerate”) entered into a purchase agreement, under which ReGenerate agreed to purchase Generation’s interest in the Albany Green Energy biomass facility. As a result, in the second quarter of 2021, Exelon and Generation recorded a pre-tax impairment charge of $140 million within Operating and maintenance expense in Exelon’s and Generation’s Consolidated Statements of Operations and Comprehensive Income. Completion of the transaction was subject to the satisfaction of various customary closing conditions which were satisfied in the second quarter of 2021. The sale was completed on June 30, 2021 for a net purchase price of $36 million.

Regulatory Matters (All Registr

Regulatory Matters (All Registrants)	6 Months Ended
Regulatory Matters (All Registrants)	Jun. 30, 2021
Regulated Operations [Abstract]
Regulatory Matters (All Registrants)	Regulatory Matters (All Registrants) As discussed in Note 3 — Regulatory Matters of the Exelon 2020 Form 10-K, the Registrants are involved in rate and regulatory proceedings at the FERC and their state commissions. The following discusses developments in 2021 and updates to the 2020 Form 10-K. Utility Regulatory Matters (Exelon, PHI, and the Utility Registrants) Distribution Base Rate Case Proceedings The following tables show the completed and pending distribution base rate case proceedings in 2021. Completed Distribution Base Rate Case Proceedings Registrant/Jurisdiction Filing Date Service Requested Revenue Requirement (Decrease) Increase Approved Revenue Requirement (Decrease) Increase Approved ROE Approval Date Rate Effective Date ComEd - Illinois (a) April 16, 2020 Electric $ (11) $ (14) 8.38 % December 9, 2020 January 1, 2021 PECO - Pennsylvania September 30, 2020 Natural Gas 69 29 10.24 % June 22, 2021 July 1, 2021 BGE - Maryland (b) May 15, 2020 (amended September 11, 2020) Electric 203 140 9.50 % December 16, 2020 January 1, 2021 Natural Gas 108 74 9.65 % Pepco - District of Columbia (c) May 30, 2019 (amended June 1, 2020) Electric 136 109 9.275 % June 8, 2021 July 1, 2021 Pepco - Maryland (d) October 26, 2020 (amended March 31, 2021) Electric 104 52 9.55 % June 28, 2021 June 28, 2021 ACE - New Jersey (e) December 9, 2020 (amended February 26, 2021) Electric 67 41 9.60 % July 14, 2021 January 1, 2022 __________ (a) ComEd's 2021 approved revenue requirement reflects an increase of $50 million for the initial year revenue requirement for 2021 and a decrease of $64 million related to the annual reconciliation for 2019. The revenue requirement for 2021 and the revenue requirement for 2019 provide for a weighted average debt and equity return on distribution rate base of 6.28%, inclusive of an allowed ROE of 8.38%, reflecting the monthly average yields for 30-year treasury bonds plus 580 basis points. (b) Reflects a three-year cumulative multi-year plan for 2021 through 2023. The MDPSC awarded BGE electric revenue requirement increases of $59 million, $39 million, and $42 million, before offsets, in 2021, 2022, and 2023, respectively, and natural gas revenue requirement increases of $53 million, $11 million, and $10 million, before offsets, in 2021, 2022, and 2023, respectively. BGE proposed to use certain tax benefits to fully offset the increases in 2021 and 2022 and partially offset the increase in 2023. However, the MDPSC only utilized the tax benefits to fully offset the increases in 2021 such that customer rates will remain unchanged from 2020 to 2021. The MDPSC has deferred a decision on whether to use certain tax benefits to offset the customer rate increases in 2022 and 2023 and BGE cannot predict the outcome. (c) Reflects a cumulative multi-year plan with 18-months remaining in 2021 through 2022. The DCPSC awarded Pepco electric incremental revenue requirement increases of $42 million and $67 million, before offsets, for the remainder of 2021 and 2022, respectively. However, the DCPSC utilized the acceleration of refunds for certain tax benefits along with other rate relief to partially offset the customer rate increases by $22 million and $40 million for the remainder of 2021 and 2022, respectively. (d) Reflects a three-year cumulative multi-year plan for April 1, 2021 through March 31, 2024. The MDPSC awarded Pepco electric incremental revenue requirement increases of $21 million, $16 million, and $15 million, before offsets, for the 12-month periods ending March 31, 2022, 2023, and 2024, respectively. Pepco proposed to utilize certain tax benefits to fully offset the increase through 2023 and partially offset customer rate increases in 2024. However, the MDPSC only utilized the acceleration of refunds for certain tax benefits to fully offset the increases such that customer rates remain unchanged through March 31, 2022. The MDPSC has deferred decision on whether to use additional tax benefits to offset customer rate increases for periods after March 31, 2022 and Pepco cannot predict the outcome. (e) Requested and approved increases are before New Jersey sales and use tax. The order allows ACE to retain approximately $11 million of certain tax benefits which will result in a decrease to income tax expense within Exelon's, PHI's, and ACE's Consolidated Statements of Operations and Comprehensive Income in the third quarter of 2021. Pending Distribution Base Rate Case Proceedings Registrant/Jurisdiction Filing Date Service Requested Revenue Requirement Increase Requested ROE Expected Approval Timing ComEd - Illinois (a) April 16, 2021 Electric $ 51 7.36 % Fourth quarter of 2021 PECO - Pennsylvania March 30, 2021 Electric 246 10.95 % Fourth quarter of 2021 DPL - Delaware (b) March 6, 2020 (amended February 2, 2021) Electric 23 10.3 % Third quarter of 2021 __________ (a) ComEd's 2022 requested revenue requirement reflects an increase of $40 million for the initial year revenue requirement for 2022 and an increase of $11 million related to the annual reconciliation for 2020. The revenue requirement for 2022 provides for a weighted average debt and equity return on distribution rate base of 5.72%, inclusive of an allowed ROE of 7.36%, reflecting the average monthly yields for 30-year treasury bonds plus 580 basis points. The reconciliation revenue requirement for 2020 provides for a weighted average debt and equity return on distribution rate base of 5.69%, inclusive of an allowed ROE of 7.29%, reflecting the average monthly yields for 30-year treasury bonds plus 580 basis points less a performance metrics penalty of 7 basis points. (b) The rates went into effect on October 6, 2020, subject to refund. Transmission Formula Rates The Utility Registrants' transmission rates are each established based on a FERC-approved formula. ComEd, BGE, Pepco, DPL, and ACE are required to file an annual update to the FERC-approved formula on or before May 15, and PECO is required to file on or before May 31, with the resulting rates effective on June 1 of the same year. The annual update for ComEd is based on prior year actual costs and current year projected capital additions (initial year revenue requirement). The annual update for PECO is based on prior year actual costs and current year projected capital additions, accumulated depreciation, and accumulated deferred income taxes. The annual update for BGE, Pepco, DPL, and ACE is based on prior year actual costs and current year projected capital additions, accumulated depreciation, depreciation and amortization expense, and accumulated deferred income taxes. The update for ComEd also reconciles any differences between the revenue requirement in effect beginning June 1 of the prior year and actual costs incurred for that year (annual reconciliation). The update for PECO, BGE, Pepco, DPL, and ACE also reconciles any differences between the actual costs and actual revenues for the calendar year (annual reconciliation). For 2021, the following total increases/(decreases) were included in the Utility Registrants’ electric transmission formula rate updates: Registrant (a) Initial Revenue Requirement Increase (Decrease) Annual Reconciliation Increase Total Revenue Requirement Increase (b) Allowed Return on Rate Base (c) Allowed ROE (d) ComEd $ 33 $ 12 $ 45 8.20 % 11.50 % PECO (2) 26 24 7.37 % 10.35 % BGE 38 27 65 7.35 % 10.50 % Pepco (9) 21 12 7.68 % 10.50 % DPL 19 33 52 7.20 % 10.50 % ACE 27 24 51 7.45 % 10.50 % __________ (a) All rates are effective June 1, 2021 - May 31, 2022, subject to review by interested parties pursuant to review protocols of each Utility Registrants' tariff. (b) In 2020, ComEd, BGE, Pepco, DPL, and ACE's transmission revenue requirement included a one-time decrease in accordance with the April 24, 2020 settlement agreement related to excess deferred income taxes which now completed has resulted in an increase to the 2021 transmission revenue requirement. In 2020, PECO's transmission revenue requirement included a one-time decrease in accordance with the December 5, 2019 settlement agreement related to refunds which now completed has resulted in an increase to the 2021 transmission revenue requirement. (c) Represents the weighted average debt and equity return on transmission rate bases. (d) As part of the FERC-approved settlements of ComEd’s 2007 and PECO's 2017 rate cases, the rate of return on common equity is 11.50% and 10.35%, respectively, inclusive of a 50-basis-point incentive adder for being a member of a RTO, and the common equity component of the ratio used to calculate the weighted average debt and equity return for the transmission formula rate is currently capped at 55% and 55.75%, respectively. As part of the FERC-approved settlement of the ROE complaint against BGE, Pepco, DPL, and ACE, the rate of return on common equity is 10.50%, inclusive of a 50-basis-point incentive adder for being a member of a RTO. Other State Regulatory Matters Illinois Regulatory Matters Energy Efficiency Formula Rate (Exelon and ComEd). ComEd filed its annual energy efficiency formula rate update with the ICC on June 1, 2021. The filing establishes the revenue requirement used to set the rates that will take effect in January 2022 after the ICC’s review and approval. The requested revenue requirement update is based on a reconciliation of the 2020 actual costs plus projected 2022 expenditures. Initial Revenue Requirement Increase Annual Reconciliation Decrease Total Revenue Requirement Increase Requested Return on Rate Base (a) Requested ROE $ 55 $ (1) $ 54 5.72 % 7.36 % __________ (a) The requested revenue requirement increase provides for a weighted average debt and equity return on the energy efficiency regulatory asset and rate base of 5.72% inclusive of an allowed ROE of 7.36%, reflecting the monthly average yields for 30-year treasury bonds plus 580 basis points. For the 2020 reconciliation year, the requested revenue requirement provides for a weighted average debt and equity return on the energy efficiency regulatory asset and rate base of 6.26% inclusive of an allowed ROE of 8.46%, which includes an upward performance adjustment that increased the ROE. The performance adjustment can either increase or decrease the ROE based upon the achievement of energy efficiency savings goals. Maryland Regulatory Matters Maryland Order Directing the Distribution of Energy Assistance Funds (Exelon, BGE, PHI, Pepco, and DPL). On June 15, 2021, the MDPSC issued an order authorizing the disbursal of funds to utilities in accordance with Maryland COVID-19 relief legislation. Upon receipt, the funds are to be used to reduce or eliminate certain qualifying past-due residential customer receivables. Under this order, BGE, Pepco, and DPL received funds of $50 million, $12 million, and $8 million, respectively, in July 2021. New Jersey Regulatory Matters Advanced Metering Infrastructure Filing (Exelon, PHI, and ACE). On August 26, 2020, ACE filed an application with the NJBPU as was required seeking approval to deploy a smart energy network in alignment with New Jersey’s Energy Master Plan and Clean Energy Act. The proposal consisted of estimated costs totaling $220 million with deployment taking place over a 3-year implementation period from approximately 2021 to 2024 that involves the installation of an integrated system of smart meters for all customers accompanied by the requisite communications facilities and data management systems. On July 14, 2021, the NJBPU approved the settlement filed by ACE and the third parties to the proceeding. The approved settlement addresses all material aspects of ACE's smart energy network deployment plan, including cost recovery of the investment costs, incremental O&M expenses, and the unrecovered balance of existing infrastructure through future distribution rates. Regulatory Assets and Liabilities The Utility Registrants' regulatory assets and liabilities have not changed materially since December 31, 2020, unless noted below. See Note 3 — Regulatory Matters of the Exelon 2020 Form 10-K for additional information on the specific regulatory assets and liabilities. ComEd . Regulatory assets increased $116 million primarily due to an increase of $67 million in the Electric Distribution Formula Rate Annual Reconciliations regulatory asset and $85 million in the Energy Efficiency Costs regulatory asset, partially offset by a decrease of $36 million in the renewable energy regulatory asset. PECO. Regulatory assets increased $95 million primarily due to an increase of $81 million in the Deferred Income Taxes regulatory asset and $12 million in the Vacation Accrual regulatory asset. Regulatory liabilities increased by $85 million primarily due to an increase of $96 million in the Nuclear Decommissioning regulatory liability partially offset by a $13 million decrease in the Electric Energy and Natural Gas Costs regulatory liability. BGE . Regulatory liabilities decreased $109 million primarily due to a decrease of $111 million in the Deferred Income Taxes regulatory liability. Pepco . Regulatory liabilities decreased $53 million primarily due to a decrease of $46 million in the Deferred Income Taxes regulatory liability and $14 million in the Transmission Formula Rate regulatory liability partially offset by an increase of $10 million in various regulatory liabilities as a result of the Pepco DC multi-year plan. DPL . Regulatory liabilities decreased $32 million primarily due to a decrease of $26 million in the Deferred Income Taxes regulatory liability and $9 million in the Transmission Formula Rate regulatory liability. ACE . Regulatory liabilities decreased $27 million primarily due to a decrease of $20 million in the Deferred Income Taxes regulatory liability and $6 million in the Transmission Formula Rate regulatory liability. Capitalized Ratemaking Amounts Not Recognized The following table presents authorized amounts capitalized for ratemaking purposes related to earnings on shareholders’ investment that are not recognized for financial reporting purposes in Exelon's and the Utility Registrant's Consolidated Balance Sheets. These amounts will be recognized as revenues in the related Consolidated Statements of Operations and Comprehensive Income in the periods they are billable to the Utility Registrants' customers. Exelon ComEd (a) PECO BGE (b) PHI Pepco (c) DPL (c) ACE June 30, 2021 $ 48 $ 1 $ — $ 41 $ 6 $ 3 $ 3 $ — December 31, 2020 51 (1) — 45 7 4 3 — __________ (a) Reflects ComEd's unrecognized equity returns/(losses) earned/(incurred) for ratemaking purposes on its electric distribution formula rate regulatory assets. (b) BGE's authorized amounts capitalized for ratemaking purposes primarily relate to earnings on shareholders' investment on its AMI programs. (c) Pepco's and DPL's authorized amounts capitalized for ratemaking purposes relate to earnings on shareholders' investment on their respective AMI Programs and Energy Efficiency and Demand Response Programs. The earnings on energy efficiency are on Pepco DC and DPL DE programs only. Generation Regulatory Matters (Exelon and Generation) Impacts of the February 2021 Extreme Cold Weather Event and Texas-based Generating Assets Outages Beginning on February 15, 2021, Generation’s Texas-based generating assets within the ERCOT market, specifically Colorado Bend II, Wolf Hollow II, and Handley, experienced outages as a result of extreme cold weather conditions. In addition, those weather conditions drove increased demand for service, dramatically increased wholesale power prices, and also increased gas prices in certain regions. In response to the high demand and significantly reduced total generation on the system, the PUCT directed ERCOT to use an administrative price cap of $9,000 per MWh during firm load shedding events. The estimated impact to Exelon’s and Generation’s Net income for the six months ended June 30, 2021 arising from these market and weather conditions was a reduction of approximately $880 million. The estimated impact to Exelon's and Generation's Net income for the three months ended June 30, 2021 was not material. The ultimate impact to Exelon’s and Generation’s consolidated financial statements for the full year 2021 may be affected by a number of factors, including final settlement data, the impacts of customer and counterparty credit losses, any state or federal solutions to address the financial challenges caused by the event, and related litigation and contract disputes. During February and March 2021, various parties with differing interests, including generators and retail providers, filed requests with the PUCT to void the PUCT’s orders setting prices at $9,000 per MWh during firm load shedding events. Other requests were made for the PUCT to enforce its order and reduce prices for 33 hours between February 18 and February 19 after firm load shedding ceased, and to cap ancillary services at $9,000 per MWh. On March 2, 2021, a third party filed a notice of appeal in the Court of Appeals for the Third District of Texas challenging the validity of the PUCT’s actions. Generation intervened in that appeal and filed its initial brief on June 2, 2021. On April 19, 2021, Generation filed a declaratory action and request for judicial review of the PUCT’s orders setting prices at $9,000 per MWh in District Court of Travis County, Texas. Generation subsequently requested that the District Court of Travis County, Texas stay its proceeding pending action by the Court of Appeals in the third party proceeding. On May 17, 2021, Generation amended its petition for declaratory action and request for judicial review pending in the District Court of Travis County, Texas. Exelon and Generation cannot predict the outcome of these proceedings or the financial statement impact. Due to these events, a number of ERCOT market participants experienced bankruptcies or defaulted on payments to ERCOT, resulting in approximately a $3.0 billion payment shortfall in collections, which is allocated to the remaining ERCOT market participants. As of June 30, 2021, Generation has recorded its portion of this obligation of approximately $17 million on a discounted basis, which is to be paid over a term of 83 years. ERCOT rules historically have limited recovery of default from market participants to $2.5 million per month market-wide. In February 2021, the PUCT gave ERCOT discretion to disregard those rules, but ERCOT has declined to exercise that discretion thus far. On March 8, 2021, a third party filed a notice of appeal in the Court of Appeals for the Third District of Texas challenging the validity of the PUCT's order to ERCOT in February 2021. Generation intervened in that appeal and filed its initial brief on July 7, 2021. On May 7, 2021, Generation filed a declaratory action and request for judicial review of the PUCT's order in the District Court of Travis County, Texas. Generation subsequently requested that the District Court of Travis County, Texas stay its proceeding pending action by the Court of Appeals in the third party proceeding. Exelon and Generation cannot predict the outcome of these proceedings or the financial statement impact. Additionally, several legislative proposals were introduced in the Texas legislature during February and March 2021 concerning the amount, timing and allocation of recovery of the $3.0 billion shortfall, as well as recovery of other costs associated with the PUCT's directive to set prices at $9,000 per MWh. Two of these proposals were enacted into law in June 2021 and establish financing mechanisms that ERCOT and certain market participants can utilize to fund amounts owed to ERCOT. Exelon and Generation are monitoring the implementation of the legislation, which could result in further adjustment to Generation's portion of the obligation. In addition, other legislative proposals were introduced in the Texas legislature during February and March 2021 addressing cold-weather preparation for power plants and natural gas production and transportation infrastructure and the market structure for reliability services. The Texas legislature addressed these proposals by enacting a bill with a broad set of market reforms that, among other things, directed the PUCT to establish weatherization standards for electric generators within six months of enactment and gave the PUCT authority to impose administrative penalties if the new proposed standards, once adopted, are not met. On June 9, 2021, PUCT staff issued a request for comments regarding the conditions under which the PUCT should require the operation of electric generation facilities and Generation and other third parties responded on June 23, 2021. Exelon and Generation are monitoring and cannot predict the outcome of this proceeding, which could have a material adverse impact in Exelon’s and Generation’s consolidated financial statements. The legislation also directs the PUCT to evaluate whether additional ancillary services are needed for reliability in the ERCOT power region to provide adequate incentives for dispatchable generation. This evaluation is expected to be taken up by the PUCT later in 2021. In February 2021, more than 70 local distribution companies (LDCs) and natural gas pipelines in multiple states throughout the mid-continent region, where Generation serves natural gas customers, issued operational flow orders (OFOs), curtailments or other limitations on natural gas transportation or use to manage the operational integrity of the applicable LDC or pipeline system. When in effect, gas transportation or use above these limitations is subject to significant penalties according to the applicable LDCs’ and natural gas pipelines’ tariffs. Gas transportation and supply in many states became restricted due to wells freezing and pipeline compression disruption, while demand was increasing due to the extreme cold temperatures, resulting in extremely high natural gas prices. Due to the extraordinary circumstances, many LDCs and natural gas pipelines have either voluntarily waived or have sought applicable regulatory approvals to waive the tariff penalties associated with the extreme weather event. During March 2021, three natural gas pipelines filed individual petitions with the FERC requesting approval to waive OFO penalties. Generation also filed motions in March 2021 to intervene and filed comments in support of these FERC waiver requests. On March 25, 2021, the FERC issued an order on one of the petitions approving a pipeline’s request for a limited waiver of penalties for February 15, 2021. On April 23, 2021, Generation and several other entities filed a request for rehearing and a complaint requesting that FERC expand the order to include additional days of the weather event in February, from February 16 through February 19, 2021. During April 2021, the FERC issued orders on the remaining petitions approving the requests to waive the penalties. During May 2021, an LDC filed a motion with the Kansas Corporation Commission (KCC) requesting the KCC to grant a waiver from the tariff and allow the LDC to reduce the amounts assessed by permitting the removal of a multiplier from the penalty calculation. Exelon and Generation cannot predict the outcome of the pending FERC complaint proceeding, the KCC proceeding, or the determinations made by the LDCs and natural gas pipelines. New Jersey Regulatory Matters New Jersey Clean Energy Legislation. On May 23, 2018, New Jersey enacted legislation that established a ZEC program that provides compensation for nuclear plants that demonstrate to the NJBPU that they meet certain requirements, including that they make a significant contribution to air quality in the state and that their revenues are insufficient to cover their costs and risks. Under the legislation, the NJBPU will issue ZECs to qualifying nuclear power plants and the electric distribution utilities in New Jersey, including ACE, will be required to purchase those ZECs. On April 18, 2019, the NJBPU approved the award of ZECs to Salem 1 and Salem 2. Upon approval, Generation began recognizing revenue for the sale of New Jersey ZECs in the month they are generated. On March 19, 2021, a three-judge panel of the Superior Court of New Jersey Appellate Division unanimously affirmed the NJBPU’s April 2019 order awarding ZECs for the first eligibility period. On April 8, 2021, New Jersey Rate Counsel filed a notice asking the New Jersey Supreme Court to hear the appeal of the Superior Court’s order. On July 9, 2021, the New Jersey Supreme Court declined to hear the appeal. On October 1, 2020, PSEG and Generation filed applications seeking ZECs for the second eligibility period (June 2022 through May 2025). On April 27, 2021, the NJBPU approved the award of ZECs to Salem 1 and Salem 2 for the second eligibility period. On May 11, 2021, the New Jersey Rate Counsel appealed the April 27, 2021 decision to the Superior Court of New Jersey Appellate Division. Exelon and Generation cannot predict the outcome of this proceeding. See Note 7 — Early Plant Retirements for additional information related to Salem. New England Regulatory Matters Mystic Units 8 & 9 and Everett Marine Terminal Cost of Service Agreement. On March 29, 2018, Generation notified grid operator ISO-NE of its plans to early retire Mystic Units 8 and 9 absent regulatory reforms on June 1, 2022. On May 16, 2018, Generation made a filing with FERC to establish cost-of-service compensation and terms and conditions of service for Mystic Units 8 & 9 for the period between June 1, 2022 - May 31, 2024. On December 20, 2018, FERC issued an order accepting the cost of service compensation, reflecting a number of adjustments to the annual fixed revenue requirement and allowing for recovery of a substantial portion of the costs associated with the adjacent Everett Marine Terminal acquired by Generation in October 2018. Those adjustments were reflected in a compliance filing made on March 1, 2019. In the December 20, 2018 order, FERC also directed a paper hearing on ROE using a new methodology. On January 22, 2019, Exelon and several other parties filed requests for rehearing of certain findings in the order. On July 15, 2021, FERC issued an order establishing the ROE to be used in the cost of service agreement for Mystic 8 and 9 at 9.33%. On July 17, 2020, FERC issued three orders, which together affirmed the recovery of key elements of Mystic's cost of service compensation, including recovery of costs associated with the operation of the Everett Marine Terminal. FERC directed a downward adjustment to the rate base for Mystic Units 8 and 9, the effect of which will be partially offset by elimination of a crediting mechanism for third party gas sales during the term of the cost of service agreement. In addition, several parties filed protests to a compliance filing by Generation on September 15, 2020, taking issue with how gross plant in-service was calculated, and Generation filed an answer to the protests on October 21, 2020. On December 21, 2020, FERC issued an order on rehearing of the three July 17, 2020 orders, clarifying several cost of service provisions. Several parties appealed the December 21, 2020 order to the U.S. Court of Appeals for the D.C. Circuit and that appeal was consolidated with appeals of orders issued December 20, 2018 and July 17, 2020 in the Mystic proceeding. The briefing schedule for the consolidated appeal has not yet been set. On February 25, 2021, Mystic made its filing to comply with the December 21, 2020 order. On April 26, 2021, FERC rejected Mystic’s language and directed another compliance filing relating to the claw back provision language, which only applies if Mystic 8 and 9 were to continue operation after the conclusion of the cost-of-service period. FERC’s April 26, 2021 order also accepted in part and rejected in part Mystic’s September 15, 2020 compliance filing. It directed a further compliance filing in 60 days consistent with the information provided in Mystic’s October 21, 2020 answer to protests, which Mystic filed on June 2, 2021. On August 25, 2020, a group of New England generators filed a complaint against Generation seeking to extend the scope of the claw back provision in the cost-of-service agreement, whereby Generation would refund certain amounts recovered during the term of the cost of service if it returns to market afterwards. On April 15, 2021 FERC dismissed the complaint. On February 16, 2021, Generation filed an unopposed motion to voluntarily dismiss an appeal filed with the U.S. Court of Appeals for the D.C. Circuit stemming from a June 2020 complaint filed with the FERC against ISO-NE over failures to follow its tariff in evaluating Mystic for transmission security for the 2024 to 2025 Capacity Commitment Period, which was granted on February 18, 2021. See Note 7 — Early Plant Retirements for additional information on the impacts of Generation’s August 2020 decision to retire Mystic Units 8 & 9 upon expiration of the cost of service agreement. Federal Regulatory Matters PJM and NYISO MOPR Proceedings. PJM and NYISO capacity markets include a MOPR. If a resource is subjected to a MOPR, its offer is adjusted to effectively remove the revenues it receives through a state government-provided financial support program - resulting in a higher offer that may not clear the capacity market. Prior to December 19, 2019, the MOPR in PJM applied only to certain new gas-fired resources. Currently, the MOPR in NYISO applies only to certain resources in downstate New York. For Generation’s facilities in PJM and NYISO that are currently receiving ZEC compensation, an expanded MOPR would require exclusion of ZEC compensation when bidding into future capacity auctions, resulting in an increased risk of these facilities not receiving capacity revenues in future auctions. On December 19, 2019, FERC required PJM to broadly apply the MOPR to all new and existing resources including nuclear, renewables, demand response, energy efficiency, storage, and all resources owned by vertically-integrated utilities. This greatly expands the breadth and scope of PJM’s MOPR, which is effective as of PJM’s next capacity auction. While FERC included some limited exemptions, no exemptions were available to state-supported nuclear resources. FERC provided no new mechanism for accommodating state-supported resources other than the existing FRR mechanism (under which an entire utility zone would be removed from PJM’s capacity auction along with sufficient resources to support the load in such zone). In response to FERC’s order, PJM submitted a compliance filing on March 18, 2020 wherein PJM proposed tariff language interpreting and implementing FERC's directives, and proposed a schedule for resuming capacity auctions that is contingent on the timing of FERC's action on the compliance filing. On April 16, 2020, FERC issued an order largely denying most requests for rehearing of FERC's December 2019 order but granting a few clarifications that required an additional PJM compliance filing which PJM submitted on June 1, 2020. On October 15, 2020, FERC issued an order denying requests for rehearing of its April 16, 2020 order and accepting PJM’s two compliance filings, subject to a further compliance filing to revise minor aspects of the proposed MOPR methodology. As part of that order, FERC also accepted PJM’s proposal to condense the schedule of activities leading up to the next capacity auction. A number of parties, including Exelon, have filed petitions for review of FERC's orders in this proceeding, which remain pending before the Court of Appeals for the District of Columbia Circuit. In November 2020, PJM announced that it will conduct its next capacity auction beginning on May 19, 2021 and ending on May 25, 2021 and will post the results on June 2, 2021. PJM conducted the auction as scheduled and, because neither Illinois nor New Jersey implemented an FRR program in their PJM zones, the MOPR applied in the capacity auction to Generation's owned or jointly owned nuclear plants in those states receiving a benefit under the Illinois ZES, or the New Jersey ZEC program. The MOPR prevented Quad Cities from clearing in the capacity auction. At the direction of the PJM Board of Managers, PJM and its stakeholders are considering MOPR reforms to ensure that the capacity market rules respect and accommodate state resource preferences such as the ZEC programs which PJM filed at FERC on July 30, 2021. Exelon cannot predict whether or when such changes can be implemented. On February 20, 2020, FERC issued an order rejecting requests to expand NYISO

Revenue from Contracts with Cus

Revenue from Contracts with Customers (All Registrants)	6 Months Ended
Revenue from Contracts with Customers (All Registrants)	Jun. 30, 2021
Revenue from Contract with Customer [Abstract]
Revenue from Contracts with Customers [Text Block]	Revenue from Contracts with Customers (All Registrants) The Registrants recognize revenue from contracts with customers to depict the transfer of goods or services to customers at an amount that the entities expect to be entitled to in exchange for those goods or services. Generation’s primary sources of revenue include competitive sales of power, natural gas, and other energy-related products and services. The Utility Registrants’ primary sources of revenue include regulated electric and gas tariff sales, distribution, and transmission services. See Note 4 — Revenue from Contracts with Customers of the Exelon 2020 Form 10-K for additional information regarding the primary sources of revenue for the Registrants. Contract Balances (All Registrants) Contract Assets Generation records contract assets for the revenue recognized on the construction and installation of energy efficiency assets and new power generating facilities before Generation has an unconditional right to bill for and receive the consideration from the customer. These contract assets are subsequently reclassified to receivables when the right to payment becomes unconditional. Generation records contract assets and contract receivables within Other current assets and Customer accounts receivable, net, respectively, within Exelon’s and Generation’s Consolidated Balance Sheets. The following table provides a rollforward of the contract assets reflected in Exelon's and Generation's Consolidated Balance Sheets for the three and six months ended June 30, 2021 and 2020. The Utility Registrants do not have any contract assets. Exelon Generation Balance as of December 31, 2020 $ 144 $ 144 Amounts reclassified to receivables (16) (16) Revenues recognized 13 13 Amounts previously held-for-sale 12 12 Balance as of March 31, 2021 153 153 Amounts reclassified to receivables (12) (12) Revenues recognized 9 9 Balance as of June 30, 2021 $ 150 $ 150 Exelon Generation Balance as of December 31, 2019 $ 174 $ 174 Amounts reclassified to receivables (19) (19) Revenues recognized 17 17 Balance as of March 31, 2020 172 172 Amounts reclassified to receivables (26) (26) Revenues recognized 13 13 Balance as of June 30, 2020 $ 159 $ 159 Contract Liabilities The Registrants record contract liabilities when consideration is received or due prior to the satisfaction of the performance obligations. The Registrants record contract liabilities within Other current liabilities and Other noncurrent liabilities within the Registrants' Consolidated Balance Sheets. For Generation, these contract liabilities primarily relate to upfront consideration received or due for equipment service plans, and the Illinois ZEC program that introduces a cap on the total consideration to be received by Generation. For PHI, Pepco, DPL, and ACE these contract liabilities primarily relate to upfront consideration received in the third quarter of 2020 for a collaborative arrangement with an unrelated owner and manager of communication infrastructure. The revenue attributable to this arrangement will be recognized as operating revenue over the 35 years under the collaborative arrangement. The following table provides a rollforward of the contract liabilities reflected in Exelon's, Generation's, PHI's, Pepco's, DPL's, and ACE's Consolidated Balance Sheets for the three and six months ended June 30, 2021 and 2020. As of June 30, 2021 and December 31, 2020, ComEd's, PECO's, and BGE's contract liabilities were immaterial. Exelon Generation PHI Pepco DPL ACE Balance as of December 31, 2020 $ 151 $ 84 $ 118 $ 94 $ 12 $ 12 Consideration received or due 20 31 — — — — Revenues recognized (27) (64) (2) (2) — — Amounts previously held-for-sale 3 3 — — — — Balance as of March 31, 2021 147 54 116 92 12 12 Consideration received or due 17 39 — — — — Revenues recognized (32) (68) (3) (1) (1) (1) Balance as of June 30, 2021 $ 132 $ 25 $ 113 $ 91 $ 11 $ 11 Exelon Generation PHI Pepco DPL ACE Balance as of December 31, 2019 $ 33 $ 71 $ — $ — $ — $ — Consideration received or due 20 55 — — — — Revenues recognized (24) (70) — — — — Balance as of March 31, 2020 29 56 — — — — Consideration received or due 13 34 — — — — Revenues recognized (22) (63) — — — — Balance as of June 30, 2020 $ 20 $ 27 $ — $ — $ — $ — The following table reflects revenues recognized in the three and six months ended June 30, 2021 and 2020, which were included in contract liabilities at December 31, 2020 and 2019, respectively: Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 Exelon $ 17 $ 14 $ 34 $ 23 Generation 41 42 79 61 PHI 3 — 5 — Pepco 1 — 3 — DPL 1 — 1 — ACE 1 — 1 — Transaction Price Allocated to Remaining Performance Obligations (All Registrants) The following table shows the amounts of future revenues expected to be recorded in each year for performance obligations that are unsatisfied or partially unsatisfied as of June 30, 2021. This disclosure only includes contracts for which the total consideration is fixed and determinable at contract inception. The average contract term varies by customer type and commodity but ranges from one month to several years. This disclosure excludes Generation's power and gas sales contracts as they contain variable volumes and/or variable pricing. This disclosure also excludes the Utility Registrants' gas and electric tariff sales contracts and transmission revenue contracts as they generally have an original expected duration of one year or less and, therefore, do not contain any future, unsatisfied performance obligations to be included in this disclosure. 2021 2022 2023 2024 2025 and thereafter Total Exelon $ 149 $ 100 $ 46 $ 31 $ 180 $ 506 Generation 223 146 54 29 94 546 PHI 5 8 8 6 86 113 Pepco 3 6 6 5 71 91 DPL 1 1 1 — 8 11 ACE 1 1 1 1 7 11 Revenue Disaggregation (All Registrants) The Registrants disaggregate revenue recognized from contracts with customers into categories that depict how the nature, amount, timing, and uncertainty of revenue and cash flows are affected by economic factors. See Note 5 — Segment Information for the presentation of the Registrant's revenue disaggregation.

Segment Information (All Regist

Segment Information (All Registrants)	6 Months Ended
Segment Information (All Registrants)	Jun. 30, 2021
Segment Reporting [Abstract]
Segment Information (All Registrants)	Segment Information (All Registrants) Operating segments for each of the Registrants are determined based on information used by the CODM in deciding how to evaluate performance and allocate resources at each of the Registrants. Exelon has eleven reportable segments, which include Generation's five reportable segments consisting of the Mid-Atlantic, Midwest, New York, ERCOT, and all other power regions referred to collectively as “Other Power Regions” and ComEd, PECO, BGE, and PHI's three reportable segments consisting of Pepco, DPL, and ACE. ComEd, PECO, BGE, Pepco, DPL, and ACE each represent a single reportable segment, and as such, no separate segment information is provided for these Registrants. Exelon, ComEd, PECO, BGE, Pepco, DPL, and ACE's CODMs evaluate the performance of and allocate resources to ComEd, PECO, BGE, Pepco, DPL, and ACE based on net income. The basis for Generation's reportable segments is the integrated management of its electricity business that is located in different geographic regions, and largely representative of the footprints of ISO/RTO and/or NERC regions, which utilize multiple supply sources to provide electricity through various distribution channels (wholesale and retail). Generation's hedging strategies and risk metrics are also aligned to these same geographic regions. Descriptions of each of Generation’s five reportable segments are as follows: • Mid-Atlantic represents operations in the eastern half of PJM, which includes New Jersey, Maryland, Virginia, West Virginia, Delaware, the District of Columbia, and parts of Pennsylvania and North Carolina. • Midwest represents operations in the western half of PJM and the United States footprint of MISO, excluding MISO’s Southern Region. • New York represents operations within NYISO. • ERCOT represents operations within Electric Reliability Council of Texas. • Other Power Regions: • New England represents the operations within ISO-NE. • South represents operations in the FRCC, MISO’s Southern Region, and the remaining portions of the SERC not included within MISO or PJM. • West represents operations in the WECC, which includes California ISO. • Canada represents operations across the entire country of Canada and includes AESO, OIESO, and the Canadian portion of MISO. The CODMs for Exelon and Generation evaluate the performance of Generation’s electric business activities and allocate resources based on RNF. Generation believes that RNF is a useful measurement of operational performance. RNF is not a presentation defined under GAAP and may not be comparable to other companies’ presentations or deemed more useful than the GAAP information provided elsewhere in this report. Generation’s operating revenues include all sales to third parties and affiliated sales to the Utility Registrants. Purchased power costs include all costs associated with the procurement and supply of electricity including capacity, energy, and ancillary services. Fuel expense includes the fuel costs for Generation’s owned generation and fuel costs associated with tolling agreements. The results of Generation's other business activities are not regularly reviewed by the CODM and are therefore not classified as operating segments or included in the regional reportable segment amounts. These activities include natural gas, as well as other miscellaneous business activities that are not significant to Generation's overall operating revenues or results of operations. Further, Generation’s unrealized mark-to-market gains and losses on economic hedging activities and its amortization of certain intangible assets and liabilities relating to commodity contracts recorded at fair value from mergers and acquisitions are also excluded from the regional reportable segment amounts. Exelon and Generation do not use a measure of total assets in making decisions regarding allocating resources to or assessing the performance of these reportable segments. An analysis and reconciliation of the Registrants’ reportable segment information to the respective information in the consolidated financial statements for the three and six months ended June 30, 2021 and 2020 is as follows: Three Months Ended June 30, 2021 and 2020 Generation ComEd PECO BGE PHI Other (a) Intersegment Exelon Operating revenues (b) : 2021 Competitive businesses electric revenues $ 3,747 $ — $ — $ — $ — $ — $ (250) $ 3,497 Competitive businesses natural gas revenues 507 — — — — — — 507 Competitive businesses other revenues (101) — — — — — (3) (104) Rate-regulated electric revenues — 1,517 610 558 1,113 — (11) 3,787 Rate-regulated natural gas revenues — — 83 124 24 — (3) 228 Shared service and other revenues — — — — 3 524 (527) — Total operating revenues $ 4,153 $ 1,517 $ 693 $ 682 $ 1,140 $ 524 $ (794) $ 7,915 2020 Competitive businesses electric revenues $ 3,414 $ — $ — $ — $ — $ — $ (268) $ 3,146 Competitive businesses natural gas revenues 353 — — — — — — 353 Competitive businesses other revenues 113 — — — — — (1) 112 Rate-regulated electric revenues — 1,417 586 504 983 — (15) 3,475 Rate-regulated natural gas revenues — — 95 112 30 — (1) 236 Shared service and other revenues — — — — 3 472 (475) — Total operating revenues $ 3,880 $ 1,417 $ 681 $ 616 $ 1,016 $ 472 $ (760) $ 7,322 Generation ComEd PECO BGE PHI Other (a) Intersegment Exelon Intersegment revenues (c) : 2021 $ 254 $ 5 $ 2 $ 7 $ 4 $ 522 $ (794) $ — 2020 271 11 2 4 3 470 (760) 1 Depreciation and amortization: 2021 $ 930 $ 296 $ 87 $ 141 $ 194 $ 18 $ — $ 1,666 2020 300 274 88 129 191 19 — 1,001 Operating expenses: 2021 $ 4,469 $ 1,196 $ 552 $ 620 $ 955 $ 537 $ (768) $ 7,561 2020 3,547 1,345 618 573 956 478 (748) 6,769 Interest expense, net: 2021 $ 76 $ 98 $ 42 $ 34 $ 67 $ 79 $ — $ 396 2020 87 98 36 32 67 107 — 427 Income (loss) before income taxes: 2021 $ 124 $ 238 $ 106 $ 37 $ 138 $ (92) $ — $ 551 2020 860 (15) 32 17 7 (108) 1 794 Income Taxes: 2021 $ 110 $ 46 $ 2 $ (8) $ (3) $ (73) $ — $ 74 2020 329 46 (7) (22) (87) (40) — 219 Net income (loss): 2021 $ 13 $ 192 $ 104 $ 45 $ 141 $ (19) $ — $ 476 2020 529 (61) 39 39 94 (67) 1 574 Capital Expenditures: 2021 $ 337 $ 549 $ 282 $ 284 $ 433 $ 15 $ — $ 1,900 2020 372 523 253 265 310 34 — 1,757 (a) Other primarily includes Exelon’s corporate operations, shared service entities, and other financing and investment activities. (b) Includes gross utility tax receipts from customers. The offsetting remittance of utility taxes to the governing bodies is recorded in expenses in the Registrants’ Consolidated Statements of Operations and Comprehensive Income. See Note 18— Supplemental Financial Information for additional information on total utility taxes. (c) Intersegment revenues exclude sales to unconsolidated affiliates. The intersegment profit associated with Generation’s sale of certain products and services by and between Exelon’s segments is not eliminated in consolidation due to the recognition of intersegment profit in accordance with regulatory accounting guidance. For Exelon, these amounts are included in Operating revenues in the Consolidated Statements of Operations and Comprehensive Income. See Note 19— Related Party Transactions for additional information on intersegment revenues. PHI: Pepco DPL ACE Other (a) Intersegment PHI Operating revenues (b) : 2021 Rate-regulated electric revenues $ 523 $ 274 $ 319 $ — $ (3) $ 1,113 Rate-regulated natural gas revenues — 24 — — — 24 Shared service and other revenues — — — 95 (92) 3 Total operating revenues $ 523 $ 298 $ 319 $ 95 $ (95) $ 1,140 2020 Rate-regulated electric revenues $ 494 $ 237 $ 256 $ — $ (4) $ 983 Rate-regulated natural gas revenues — 30 — — — 30 Shared service and other revenues — — — 97 (94) 3 Total operating revenues $ 494 $ 267 $ 256 $ 97 $ (98) $ 1,016 Intersegment revenues (c) : 2021 $ 1 $ 2 $ 1 $ 95 $ (95) $ 4 2020 1 2 1 97 (98) 3 Depreciation and amortization: 2021 $ 96 $ 51 $ 40 $ 7 $ — $ 194 2020 92 47 44 8 — 191 Operating expenses: 2021 $ 429 $ 255 $ 269 $ 97 $ (95) $ 955 2020 436 263 258 97 (98) 956 Interest expense, net: 2021 $ 35 $ 16 $ 14 $ 2 $ — $ 67 2020 34 15 15 3 — 67 Income (loss) before income taxes: 2021 $ 72 $ 31 $ 36 $ (1) $ — $ 138 2020 33 (9) (15) (2) — 7 Income Taxes: 2021 $ (3) $ 1 $ (1) $ — $ — $ (3) 2020 (24) (28) (33) (2) — (87) Net income (loss): 2021 $ 75 $ 30 $ 37 $ (1) $ — $ 141 2020 57 19 18 — — 94 Capital Expenditures: 2021 $ 219 $ 99 $ 116 $ (1) $ — $ 433 2020 144 89 77 — — 310 __________ (a) Other primarily includes PHI’s corporate operations, shared service entities, and other financing and investment activities. (b) Includes gross utility tax receipts from customers. The offsetting remittance of utility taxes to the governing bodies is recorded in expenses in the Registrants’ Consolidated Statements of Operations and Comprehensive Income. See Note 18— Supplemental Financial Information for additional information on total utility taxes. (c) Includes intersegment revenues with ComEd, BGE, and PECO, which are eliminated at Exelon. The following tables disaggregate the Registrants' revenue recognized from contracts with customers into categories that depict how the nature, amount, timing, and uncertainty of revenue and cash flows are affected by economic factors. For Generation, the disaggregation of revenues reflects Generation’s two primary products of power sales and natural gas sales, with further disaggregation of power sales provided by geographic region. For the Utility Registrants, the disaggregation of revenues reflects the two primary utility services of rate-regulated electric sales and rate-regulated natural gas sales (where applicable), with further disaggregation of these tariff sales provided by major customer groups. Exelon’s disaggregated revenues are consistent with Generation and the Utility Registrants, but exclude any intercompany revenues. Competitive Business Revenues (Generation): Three Months Ended June 30, 2021 Revenues from external customers (a) Intersegment Total Contracts with customers Other (b) Total Mid-Atlantic $ 1,062 $ 24 $ 1,086 $ 5 $ 1,091 Midwest 975 (13) 962 — 962 New York 376 5 381 — 381 ERCOT 179 92 271 4 275 Other Power Regions 921 126 1,047 (9) 1,038 Total Competitive Businesses Electric Revenues 3,513 234 3,747 — 3,747 Competitive Businesses Natural Gas Revenues 253 254 507 — 507 Competitive Businesses Other Revenues (c) 107 (208) (101) — (101) Total Generation Consolidated Operating Revenues $ 3,873 $ 280 $ 4,153 $ — $ 4,153 Three Months Ended June 30, 2020 Revenues from external customers (a) Intersegment Total Contracts with customers Other (b) Total Mid-Atlantic $ 1,100 $ (35) $ 1,065 $ 9 $ 1,074 Midwest 855 107 962 — 962 New York 336 5 341 (1) 340 ERCOT 175 52 227 7 234 Other Power Regions 776 43 819 (15) 804 Total Competitive Businesses Electric Revenues 3,242 172 3,414 — 3,414 Competitive Businesses Natural Gas Revenues 209 144 353 — 353 Competitive Businesses Other Revenues (c) 86 27 113 — 113 Total Generation Consolidated Operating Revenues $ 3,537 $ 343 $ 3,880 $ — $ 3,880 __________ (a) Includes all wholesale and retail electric sales to third parties and affiliated sales to the Utility Registrants. (b) Includes revenues from derivatives and leases. (c) Other represents activities not allocated to a region. See text above for a description of included activities. Includes unrealized mark-to-market losses of $239 million and gains of $21 million in 2021 and 2020, respectively, and elimination of intersegment revenues. Revenues net of purchased power and fuel expense (Generation): Three Months Ended June 30, 2021 Three Months Ended June 30, 2020 RNF from external customers (a) Intersegment Total RNF RNF from external customers (a) Intersegment Total RNF Mid-Atlantic $ 567 $ 5 $ 572 $ 516 $ 9 $ 525 Midwest 658 — 658 702 1 703 New York 289 3 292 243 3 246 ERCOT 80 3 83 92 5 97 Other Power Regions 157 (21) 136 181 (24) 157 Total Revenues net of purchased power and fuel expense for Reportable Segments 1,751 (10) 1,741 1,734 (6) 1,728 Other (b) 455 10 465 204 6 210 Total Generation Revenues net of purchased power and fuel expense $ 2,206 $ — $ 2,206 $ 1,938 $ — $ 1,938 __________ (a) Includes purchases and sales from/to third parties and affiliated sales to the Utility Registrants. (b) Other represents activities not allocated to a region. See text above for a description of included activities. Includes unrealized mark-to-market gains of $314 million and gains of $85 million in 2021 and 2020, respectively and the elimination of intersegment RNF. Electric and Gas Revenue by Customer Class (Utility Registrants): Three Months Ended June 30, 2021 Revenues from contracts with customers ComEd PECO BGE PHI Pepco DPL ACE Rate-regulated electric revenues Residential $ 759 $ 383 $ 299 $ 537 $ 223 $ 147 $ 167 Small commercial & industrial 377 99 60 124 32 46 46 Large commercial & industrial 138 59 108 257 188 22 47 Public authorities & electric railroads 11 8 7 17 10 3 4 Other (a) 214 54 87 139 50 46 43 Total rate-regulated electric revenues (b) $ 1,499 $ 603 $ 561 $ 1,074 $ 503 $ 264 $ 307 Rate-regulated natural gas revenues Residential $ — $ 55 $ 81 $ 12 $ — $ 12 $ — Small commercial & industrial — 22 13 6 — 6 — Large commercial & industrial — — 27 1 — 1 — Transportation — 5 — 3 — 3 — Other (c) — 1 6 2 — 2 — Total rate-regulated natural gas revenues (d) $ — $ 83 $ 127 $ 24 $ — $ 24 $ — Total rate-regulated revenues from contracts with customers $ 1,499 $ 686 $ 688 $ 1,098 $ 503 $ 288 $ 307 Other revenues Revenues from alternative revenue programs $ 9 $ 7 $ (10) $ 41 $ 19 $ 10 $ 12 Other rate-regulated electric revenues (e) 9 — 3 1 1 — — Other rate-regulated natural gas revenues (e) — — 1 — — — — Total other revenues $ 18 $ 7 $ (6) $ 42 $ 20 $ 10 $ 12 Total rate-regulated revenues for reportable segments $ 1,517 $ 693 $ 682 $ 1,140 $ 523 $ 298 $ 319 Three Months Ended June 30, 2020 Revenues from contracts with customers ComEd PECO BGE PHI Pepco DPL ACE Rate-regulated electric revenues Residential $ 767 $ 377 $ 304 $ 529 $ 237 $ 147 $ 145 Small commercial & industrial 327 88 51 105 29 39 37 Large commercial & industrial 119 55 94 240 175 22 43 Public authorities & electric railroads 11 7 7 15 8 3 4 Other (a) 218 55 76 161 58 51 53 Total rate-regulated electric revenues (b) $ 1,442 $ 582 $ 532 $ 1,050 $ 507 $ 262 $ 282 Rate-regulated natural gas revenues Residential $ — $ 70 $ 81 $ 17 $ — $ 17 $ — Small commercial & industrial — 19 12 8 — 8 — Large commercial & industrial — — 24 1 — 1 — Transportation — 6 — 3 — 3 — Other (c) — 1 3 1 — 1 — Total rate-regulated natural gas revenues (d) $ — $ 96 $ 120 $ 30 $ — $ 30 $ — Total rate-regulated revenues from contracts with customers $ 1,442 $ 678 $ 652 $ 1,080 $ 507 $ 292 $ 282 Other revenues Revenues from alternative revenue programs $ (25) $ 4 $ (37) $ (64) $ (13) $ (25) $ (26) Other rate-regulated electric revenues (e) — — 1 — — — — Other rate-regulated natural gas revenues (e) — (1) — — — — — Total other revenues $ (25) $ 3 $ (36) $ (64) $ (13) $ (25) $ (26) Total rate-regulated revenues for reportable segments $ 1,417 $ 681 $ 616 $ 1,016 $ 494 $ 267 $ 256 __________ (a) Includes revenues from transmission revenue from PJM, wholesale electric revenue and mutual assistance revenue. (b) Includes operating revenues from affiliates in 2021 and 2020 respectively of: • $5 million, $11 million at ComEd • $1 million, $1 million at PECO • $4 million, $3 million at BGE • $4 million, $3 million at PHI • $1 million, $1 million at Pepco • $2 million, $2 million at DPL • $1 million, $1 million at ACE (c) Includes revenues from off-system natural gas sales. (d) Includes operating revenues from affiliates in 2021 and 2020 respectively of: • less than $1 million at PECO both 2021 and 2020 • $3 million, $1 million at BGE (e) Includes late payment charge revenues. Six Months Ended June 30, 2021 and 2020 Generation ComEd PECO BGE PHI Other (a) Intersegment Exelon Operating revenues (b) : 2021 Competitive businesses electric revenues $ 7,935 $ — $ — $ — $ — $ — $ (546) $ 7,389 Generation ComEd PECO BGE PHI Other (a) Intersegment Exelon Competitive businesses natural gas revenues 1,833 — — — — — — 1,833 Competitive businesses other revenues (56) — — — — — (1) (57) Rate-regulated electric revenues — 3,052 1,271 1,190 2,283 — (21) 7,775 Rate-regulated natural gas revenues — — 311 466 95 — (7) 865 Shared service and other revenues — — — — 6 1,013 (1,019) — Total operating revenues $ 9,712 $ 3,052 $ 1,582 $ 1,656 $ 2,384 $ 1,013 $ (1,594) $ 17,805 2020 Competitive businesses electric revenues $ 7,165 $ — $ — $ — $ — $ — $ (594) $ 6,571 Competitive businesses natural gas revenues 1,025 — — — — — (3) 1,022 Competitive businesses other revenues 423 — — — — — (2) 421 Rate-regulated electric revenues — 2,856 1,189 1,118 2,086 — (27) 7,222 Rate-regulated natural gas revenues — — 304 436 94 — (2) 832 Shared service and other revenues — — — — 7 953 (959) 1 Total operating revenues $ 8,613 $ 2,856 $ 1,493 $ 1,554 $ 2,187 $ 953 $ (1,587) $ 16,069 Intersegment revenues (c) : 2021 $ 549 $ 11 $ 4 $ 13 $ 7 $ 1,010 $ (1,594) $ — 2020 601 16 4 10 7 949 (1,585) 2 Depreciation and amortization: 2021 $ 1,869 $ 589 $ 173 $ 293 $ 404 $ 35 $ — $ 3,363 2020 604 547 173 272 385 42 — 2,023 Operating expenses: 2021 $ 11,141 $ 2,406 $ 1,231 $ 1,372 $ 2,013 $ 1,029 $ (1,549) $ 17,643 2020 7,947 2,497 1,242 1,263 1,955 958 (1,564) 14,298 Interest expense, net: 2021 $ 148 $ 193 $ 80 $ 67 $ 134 $ 161 $ — $ 783 2020 197 192 71 64 134 179 — 837 Generation ComEd PECO BGE PHI Other (a) Intersegment Exelon Income (loss) before income taxes: 2021 $ (823) $ 475 $ 283 $ 233 $ 273 $ (174) $ 1 $ 268 2020 313 189 187 237 126 (175) 2 879 Income Taxes: 2021 $ (70) $ 85 $ 12 $ (21) $ 5 $ 44 $ — $ 55 2020 (59) 82 9 18 (76) (49) — (75) Net income (loss): 2021 $ (756) $ 390 $ 271 $ 254 $ 269 $ (218) $ 1 $ 211 2020 368 107 178 219 202 (126) 2 950 Capital Expenditures: 2021 $ 719 $ 1,162 $ 577 $ 620 $ 889 $ 73 $ — $ 4,040 2020 930 1,029 512 548 686 68 — 3,773 Total assets: June 30, 2021 $ 45,821 $ 35,324 $ 13,491 $ 12,186 $ 24,235 $ 8,507 $ (10,168) $ 129,396 December 31, 2020 48,094 34,466 12,531 11,650 23,736 9,005 (10,165) 129,317 __________ (a) Other primarily includes Exelon’s corporate operations, shared service entities, and other financing and investment activities. (b) Includes gross utility tax receipts from customers. The offsetting remittance of utility taxes to the governing bodies is recorded in expenses in the Registrants’ Consolidated Statements of Operations and Comprehensive Income. See Note 18 — Supplemental Financial Information for additional information on total utility taxes. (c) Intersegment revenues exclude sales to unconsolidated affiliates. The intersegment profit associated with Generation’s sale of certain products and services by and between Exelon’s segments is not eliminated in consolidation due to the recognition of intersegment profit in accordance with regulatory accounting guidance. For Exelon, these amounts are included in Operating revenues in the Consolidated Statements of Operations and Comprehensive Income. See Note 19 — Related Party Transactions for additional information on intersegment revenues. PHI: Pepco DPL ACE Other (a) Intersegment PHI Operating revenues (b) : 2021 Rate-regulated electric revenues $ 1,076 $ 585 $ 629 $ — $ (7) $ 2,283 Rate-regulated natural gas revenues — 95 — — — 95 Shared service and other revenues — — — 189 (183) 6 Total operating revenues $ 1,076 $ 680 $ 629 $ 189 $ (190) $ 2,384 2020 Rate-regulated electric revenues $ 1,039 $ 523 $ 532 $ — $ (8) $ 2,086 Rate-regulated natural gas revenues — 94 — — — 94 Shared service and other revenues — — — 189 (182) 7 Total operating revenues $ 1,039 $ 617 $ 532 $ 189 $ (190) $ 2,187 Intersegment revenues (c) : 2021 $ 3 $ 4 $ 1 $ 189 $ (190) $ 7 2020 3 4 1 189 (190) 7 Depreciation and amortization: 2021 $ 199 $ 104 $ 87 $ 14 $ — $ 404 2020 186 94 86 19 — 385 Operating expenses: 2021 $ 895 $ 564 $ 552 $ 192 $ (190) $ 2,013 2020 899 547 509 190 (190) 1,955 Interest expense, net: 2021 $ 69 $ 30 $ 29 $ 6 $ — $ 134 2020 68 31 29 6 — 134 Income (loss) before income taxes: 2021 $ 137 $ 92 $ 50 $ (6) $ — $ 273 2020 90 44 (1) (7) — 126 Income Taxes: 2021 $ 3 $ 6 $ (1) $ (3) $ — $ 5 2020 (19) (20) (32) (5) — (76) Net income (loss): 2021 $ 134 $ 86 $ 51 $ (2) $ — $ 269 2020 109 64 31 (2) — 202 Capital Expenditures: 2021 $ 439 $ 211 $ 239 $ — $ — $ 889 2020 324 184 178 — — 686 Total assets: June 30, 2021 $ 9,588 $ 5,229 $ 4,473 $ 5,014 $ (69) $ 24,235 December 31, 2020 9,264 5,140 4,286 5,079 (33) 23,736 __________ (a) Other primarily includes PHI’s corporate operations, shared service entities, and other financing and investment activities. (b) Includes gross utility tax receipts from customers. The offsetting remittance of utility taxes to the governing bodies is recorded in expenses in the Registrants’ Consolidated Statements of Operations and Comprehensive Income. See Note 18 — Supplemental Financial Information for additional information on total utility taxes. (c) Includes intersegment revenues with ComEd, BGE, and PECO, which are eliminated at Exelon. The following tables disaggregate the Registrants' revenue recognized from contracts with customers into categories that depict how the nature, amount, timing, and uncertainty of revenue and cash flows are affected by economic factors. For Generation, the disaggregation of revenues reflects Generation’s two primary products of power sales and natural gas sales, with further disaggregation of power sales provided by geographic region. For the Utility Registrants, the disaggregation of revenues reflects the two primary utility services of rate-regulated electric sales and rate-regulated natural gas sales (where applicable), with further disaggregation of these tariff sales provided by major customer groups. Exelon’s disaggregated revenues are consistent with Generation and the Utility Registrants, but exclude any intercompany revenues. Competitive Business Revenues (Generation): Six Months Ended June 30, 2021 Revenues from external customers (a) Intersegment Total Contracts with customers Other (b) Total Mid-Atlantic $ 2,233 $ 11 $ 2,244 $ 11 $ 2,255 Midwest 1,983 (24) 1,959 1 1,960 New York 759 (40) 719 — 719 ERCOT 533 (10) 523 9 532 Other Power Regions 2,095 395 2,490 (21) 2,469 Total Competitive Businesses Electric Revenues 7,603 332 7,935 — 7,935 Competitive Businesses Natural Gas Revenues 1,117 716 1,833 — 1,833 Competitive Businesses Other Revenues (c) 195 (251) (56) — (56) Total Generation Consolidated Operating Revenues $ 8,915 $ 797 $ 9,712 $ — $ 9,712 Six Months Ended June 30, 2020 Revenues from external customers (a) Intersegment Total Contracts with customers Other (b) Total Mid-Atlantic $ 2,365 $ (133) $ 2,232 $ 15 $ 2,247 Midwest 1,798 172 1,970 (6) 1,964 New York 672 (16) 656 (1) 655 ERCOT 330 81 411 13 424 Other Power Regions 1,782 114 1,896 (21) 1,875 Total Competitive Businesses Electric Revenues 6,947 218 7,165 — 7,165 Competitive Businesses Natural Gas Revenues 712 313 1,025 — 1,025 Competitive Businesses Other Revenues (c) 185 238 423 — 423 Total Generation Consolidated Operating Revenues $ 7,844 $ 769 $ 8,613 $ — $ 8,613 __________ (a) Includes all wholesale and retail electric sales to third parties and affiliated sales to the Utility Registrants. (b) Includes revenues from derivatives and leases. (c) Other represents activities not allocated to a region. See text above for a description of included activities. Includes unrealized mark-to-market losses of $323 million and gains of $200 million in 2021 and 2020, respectively, and elimination of intersegment revenues. Revenues net of purchased power and fuel expense (Generation): Six Months Ended June 30, 2021 Six Months Ended June 30, 2020 RNF from external customers (a) Intersegment Total RNF RNF from external customers (a) Intersegment Total RNF Mid-Atlantic $ 1,130 $ 11 $ 1,141 $ 1,074 $ 18 $ 1,092 Midwest 1,359 1 1,360 1,431 (4) 1,427 New York 531 5 536 433 7 440 ERCOT (957) (145) (1,102) 168 9 177 Other Power Regions 409 (56) 353 355 (43) 312 Total Revenues net of purchased power and fuel expense for Reportable Segments 2,472 (184) 2,288 3,461 (13) 3,448 Other (b) 683 184 867 506 13 519 Total Generation Revenues net of purchased power and fuel expense $ 3,155 $ — $ 3,155 $ 3,967 $ — $ 3,967 __________ (a) Includes purchases and sales from/to third parties and affiliated sales to the Utility Registrants. (b) Other represents activities not allocated to a region. See text above for a description of included activities. Primarily includes: • unrealized mark-to-market gains of $489 million and gains of $218 million in 2021 and 2020, respectively; • accelerated nuclear fuel amortization associated with announced early plant retirements as discussed in Note 7 - Early Plant Retirements of $106 million in 2021; and • the elimination of intersegment RNF. Electric and Gas Revenue by Customer Class (Utility Registrants): Six Months Ended June 30, 2021 Revenues from contracts with customers ComEd PECO BGE PHI Pepco DPL ACE Rate-regulated electric revenues Residential $ 1,502 $ 816 $ 662 $ 1,142 $ 476 $ 337 $ 329 Small commercial & industrial 744 199 129 242 65 92 85 Large commercial & industrial 271 116 213 505 372 43 90 Public authorities & electric railroads 22 17 13 30 16 7 7 Other (a) 433 106 165 283 101 87 95 Total rate-regulated electric revenues (b) $ 2,972 $ 1,254 $ 1,182 $ 2,202 $ 1,030 $ 566 $ 606 Rate-regulated natural gas revenues Residential $ — $ 215 $ 297 $ 57 $ — $ 57 $ — Small commercial & industrial — 81 48 24 — 24 — Large commercial & industrial — — 81 3 — 3 — Transportation — 12 — 8 — 8 — Other (c) — 3 36 2 — 3 — Total rate-regulated natural gas revenues (d) $ — $ 311 $ 462 $ 94 $ — $ 95 $ — Total rate-regulated revenues from contracts with customers $ 2,972 $ 1,565 $ 1,644 $ 2,296 $ 1,030 $ 661 $ 606 Other revenues Revenues from alternative revenue programs $ 64 $ 17 $ 8 $ 88 $ 46 $ 19 $ 23 Other rate-regulated electric revenues (e) 16 — 3 — — — — Other rate-regulated natural gas revenues (e) — — 1 — — — — Total other revenues $ 80 $ 17 $ 12 $ 88 $ 46 $ 19 $ 23 Total rate-regulated revenues for reportable segments $ 3,052 $ 1,582 $ 1,656 $ 2,384 $ 1,076 $ 680 $ 629 Six Months Ended June 30, 2020 Revenues from contracts with customers ComEd PECO BGE PHI Pepco DPL ACE Rate-regulated electric revenues Residential $ 1,468 $ 759 $ 644 $ 1,062 $ 472 $ 308 $ 282 Small commercial & industrial 689 187 118 221 65 82 74 Large commercial & industrial 253 108 198 493 363 45 85 Public authorities & electric railroads 23 14 14 30 17 6 7 Other (a) 430 113 154 333 119 105 109 Total rate-regulated electric revenues (b) $ 2,863 $ 1,181 $ 1,128 $ 2,139 $ 1,036 $ 546 $ 557 Rate-regulated natural gas revenues Residential $ — $ 220 $ 287 $ 57 $ — $ 57 $ — Small commercial & industrial — 70 46 25 — 25 — Large commercial & industrial — — 76 2 — 2 — Transportation — 12 — 7 — 7 — Other (c) — 2 13 3 — 3 — Total rate-regulated natural gas revenues (d) $ — $ 304 $ 422 $ 94 $ — $ 94 $ — Total rate-regulated revenues from contracts with customers $ 2,863 $ 1,485 $ 1,550 $ 2,233 $ 1,036 $ 640 $ 557 Other revenues Revenues from alternative revenue programs $ (13) $ 5 $ — $ (47) $ 2 $ (24) $ (25) Other rate-regulated electric revenues (e) 6 3 3 1 1 1 — Other rate-regulated natural gas revenues (e) — — 1 — — — — Total other revenues $ (7) $ 8 $ 4 $ (46) $ 3 $ (23) $ (25) Total rate-regulated revenues for reportable segments $ 2,856 $ 1,493 $ 1,554 $ 2,187 $ 1,039 $ 617 $ 532 __________ (a) Includes revenues from transmission revenue from PJM, wholesale electric revenue and mutual assistance revenue. (b) Includes operating revenues from affiliates in 2021 and 2020 respectively of: • $11 million, $16 million at ComEd • $3 million, $3 million at PECO • $5 million, $6 million at BGE • $7 million, $7 million at PHI • $3 million, $3 million at Pepco • $4 million, $4 million at DPL • $1 million, $1 million at ACE (c) Includes revenues from off-system natural gas sales. (d) Includes operating revenues from affiliates in 2021 and 2020 respectively of: • $1 million, less than $1 million at PECO • $7 million, $4 million at BGE (e) Includes late payment charge revenues.

Accounts Receivable (All Regist

Accounts Receivable (All Registrants)	6 Months Ended
Accounts Receivable (All Registrants)	Jun. 30, 2021
Credit Loss [Abstract]
Accounts Receivable (All Registrants) [Text Block]	Accounts Receivable (All Registrants) Allowance for Credit Losses on Accounts Receivable (All Registrants) The following tables present the rollforward of Allowance for Credit Losses on Customer Accounts Receivable. Three Months Ended June 30, 2021 Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE Balance as of March 31, 2021 $ 442 $ 65 $ 103 $ 130 $ 43 $ 101 $ 41 $ 25 $ 35 Plus: Current period provision for expected credit losses (29) 13 (9) (14) (14) (5) (1) (5) 1 Less: Write-offs, net of recoveries (a) 18 3 5 5 2 3 2 1 — Balance as of June 30, 2021 $ 395 $ 75 $ 89 $ 111 $ 27 $ 93 $ 38 $ 19 $ 36 Three Months Ended June 30, 2020 Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE Balance as of March 31, 2020 $ 278 $ 81 $ 71 $ 66 $ 18 $ 42 $ 15 $ 13 $ 14 Plus: Current period provision for expected credit losses 51 9 7 10 6 19 8 5 6 Less: Write-offs, net of recoveries (a) 12 1 6 5 1 (1) (1) — — Less: Sale of customer accounts receivable (b) 56 56 — — — — — — — Balance as of June 30, 2020 $ 261 $ 33 $ 72 $ 71 $ 23 $ 62 $ 24 $ 18 $ 20 Six Months Ended June 30, 2021 Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE Balance as of December 31, 2020 $ 366 $ 32 $ 97 $ 116 $ 35 $ 86 $ 32 $ 22 $ 32 Plus: Current period provision for expected credit losses (c) 75 47 12 6 (5) 15 10 1 4 Less: Write-offs, net of recoveries (a) 46 4 20 11 3 8 4 4 — Balance as of June 30, 2021 $ 395 $ 75 $ 89 $ 111 $ 27 $ 93 $ 38 $ 19 $ 36 Six Months Ended June 30, 2020 Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE Balance as of December 31, 2019 $ 243 $ 80 $ 59 $ 55 $ 12 $ 37 $ 13 $ 11 $ 13 Plus: Current period provision for expected credit losses 106 13 25 28 14 26 11 7 8 Less: Write-offs, net of recoveries (a) 32 4 12 12 3 1 — — 1 Less: Sale of customer accounts receivable (b) 56 56 — — — — — — — Balance as of June 30, 2020 $ 261 $ 33 $ 72 $ 71 $ 23 $ 62 $ 24 $ 18 $ 20 __________ (a) Recoveries were not material to the Registrants. (b) See below for additional information on the sale of customer accounts receivable at Generation in the second quarter of 2020. (c) For Generation, primarily relates to the impacts of the February 2021 extreme cold weather event. See Note 3 — Regulatory Matters for additional information. The following tables present the rollforward of Allowance for Credit Losses on Other Accounts Receivable. Three Months Ended June 30, 2021 Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE Balance as of March 31, 2021 $ 79 $ — $ 22 $ 11 $ 9 $ 37 $ 15 $ 10 $ 12 Plus: Current period provision for expected credit losses (4) 1 (3) (3) — 1 1 (1) 1 Less: Write-offs, net of recoveries (a) 3 — 1 1 1 — — — — Balance as of June 30, 2021 $ 72 $ 1 $ 18 $ 7 $ 8 $ 38 $ 16 $ 9 $ 13 Three Months Ended June 30, 2020 Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE Balance as of March 31, 2020 $ 52 $ — $ 22 $ 7 $ 5 $ 18 $ 8 $ 4 $ 6 Plus: Current period provision for expected credit losses 12 — 1 1 2 8 3 3 2 Less: Write-offs, net of recoveries (a) 3 — 1 1 1 — — — — Balance as of June 30, 2020 $ 61 $ — $ 22 $ 7 $ 6 $ 26 $ 11 $ 7 $ 8 Six Months Ended June 30, 2021 Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE Balance as of December 31, 2020 $ 71 $ — $ 21 $ 8 $ 9 $ 33 $ 13 $ 9 $ 11 Plus: Current period provision for expected credit losses 6 1 (2) 1 1 5 3 — 2 Less: Write-offs, net of recoveries (a) 5 — 1 2 2 — — — — Balance as of June 30, 2021 $ 72 $ 1 $ 18 $ 7 $ 8 $ 38 $ 16 $ 9 $ 13 Six Months Ended June 30, 2020 Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE Balance as of December 31, 2019 $ 48 $ — $ 20 $ 7 $ 5 $ 16 $ 7 $ 4 $ 5 Plus: Current period provision for expected credit losses 20 — 4 2 4 10 4 3 3 Less: Write-offs, net of recoveries (a) 7 — 2 2 3 — — — — Balance as of June 30, 2020 $ 61 $ — $ 22 $ 7 $ 6 $ 26 $ 11 $ 7 $ 8 __________ (a) Recoveries were not material to the Registrants. Unbilled Customer Revenue (All Registrants) The following table provides additional information about unbilled customer revenues recorded in the Registrants' Consolidated Balance Sheets as of June 30, 2021 and December 31, 2020. Unbilled customer revenues (a) Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE June 30, 2021 $ 1,029 $ 329 $ 263 $ 131 $ 119 $ 187 $ 90 $ 39 $ 58 December 31, 2020 998 258 218 147 197 178 87 62 29 __________ (a) Unbilled customer revenues are classified in Customer accounts receivables, net in the Registrants' Consolidated Balance Sheets. Sales of Customer Accounts Receivable (Exelon and Generation) On April 8, 2020, NER, a bankruptcy remote, special purpose entity, which is wholly-owned by Generation, entered into a revolving accounts receivable financing arrangement with a number of financial institutions and a commercial paper conduit (the Purchasers) to sell certain customer accounts receivable (the Facility). The Facility had a maximum funding limit o f $750 million and was scheduled to expire on April 7, 2021, unless renewed by the mutual consent of the parties in accordance with its terms. The Facility was renewed on March 29, 2021. The Facility term was extended through March 29, 2024, unless further renewed by the mutual consent of the parties, and the maximum funding limit was increased to $900 million. Un der the Facility, NER may sell eligible short-term customer accounts receivable to the Purchasers in exchange for cash and subordinated interest. The transfers are reported as sales of receivables in Exelon’s and Generation’s consolidated financial statements. The subordinated interest in collections upon the receivables sold to the Purchasers is referred to as the DPP, which is reflected in Other current assets on Exelon’s and Generation’s Consolidated Balance Sheets. The Facility requires the balance of eligible receivables to be maintained at or above the balance of cash proceeds received from the Purchasers. To the extent the eligible receivables decrease below such balance, Generation is required to repay cash to the Purchasers. When eligible receivables exceed cash proceeds, Generation has the ability to increase the cash received up to the maximum funding limit. These cash inflows and outflows impact the DPP. On April 8, 2020, Generation derecognized and transferred approximatel y $1.2 billion of receivables at fair value to the Purchasers in exchange for approximately $500 million in cash purchase price and $650 million of DP P. During the first quarter of 2021, Generation received additional c ash of $250 million from the Purchasers for the remaining available funding in the Facility. Additionally, during the first quarter of 2021, Generation received cash of approxi mately $150 million from the Purchasers in connection with the increased funding limit at the time of the Facility renewal. During the second quarter of 2021, Generation returned cash of $50 million to the Purchasers due to the eligible receivables decreasing temporarily. Subsequently, in the second quarter, Generation received cash of $50 million from the Purchasers as a result of an increase in the eligible receivable balance. The $50 million cash outflow and inflow is included in the Collection of DPP line within Cash flows from investing activities in Exelon’s and Generation’s Consolidated Statements of Cash Flows. The following table summarizes the impact of the sale of certain receivables: June 30, 2021 December 31, 2020 Derecognized receivables transferred at fair value $ 1,274 $ 1,139 Cash proceeds received 900 500 DPP 374 639 Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 Loss on sale of receivables (a) $ 8 $ 15 $ 25 $ 15 __________ (a) Reflected in Operating and maintenance expense on Exelon's and Generation's Consolidated Statements of Operations and Comprehensive Income. Six Months Ended June 30, 2021 2020 Proceeds from new transfers (a) $ 2,689 $ 927 Cash collections received on DPP and reinvested in the Facility (b) 1,809 1,102 Cash collections reinvested in the Facility 4,498 2,029 __________ (a) Customer accounts receivable sold into the Facility were $4,647 million and $2,032 million for the six months ended June 30, 2021 and June 30, 2020, respectively (b) Does not include the $400 million in cash proceeds received from the Purchasers in the first quarter of 2021. Generation’s risk of loss following the transfer of accounts receivable is limited to the DPP outstanding. Payment of DPP is not subject to significant risks other than delinquencies and credit losses on accounts receivable transferred, which have historically been and are expected to be immaterial. Generation continues to service the receivables sold in exchange for a servicing fee. Generation did not record a servicing asset or liability as the servicing fees were immaterial. Generation recognizes the cash proceeds received upon sale in Net cash provided by operating activities in the Consolidated Statements of Cash Flows. The collection and reinvestment of DPP is recognized in Net cash provided by investing activities of the Consolidated Statements of Cash Flows. See Note 14 — Fair Value of Financial Assets and Liabilities and Note 17 — Variable Interest Entities for additional information. Other Purchases and Sales of Customer and Other Accounts Receivables (All Registrants) Generation is required, under supplier tariffs in ISO-NE, MISO, NYISO, and PJM, to sell customer and other receivables to utility companies, which include the Utility Registrants. The Utility Registrants are required, under separate legislation and regulations in Illinois, Pennsylvania, Maryland, District of Columbia, Delaware, and New Jersey, to purchase certain receivables from alternative retail electric and, as applicable, natural gas suppliers that participate in the utilities' consolidated billing. The following tables present the total receivables purchased and sold. Six Months Ended June 30, 2021 Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE Total receivables purchased $ 1,823 $ — $ 485 $ 507 $ 343 $ 503 $ 310 $ 103 $ 90 Total receivables sold 92 107 — — — — — — — Related party transactions: Receivables purchased from Generation — — — — 15 — — — — Receivables sold to the Utility Registrants — 15 — — — — — — — Six Months Ended June 30, 2020 Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE Total receivables purchased $ 1,584 $ — $ 518 $ 494 $ 333 $ 485 $ 303 $ 98 $ 84 Total receivables sold 533 779 — — — — — — — Related party transactions: Receivables purchased from Generation — — 34 67 73 72 51 13 8 Receivables sold to the Utility Registrants — 246 — — — — — — —

Early Plant Retirements (Exelon

Early Plant Retirements (Exelon and Generation)	6 Months Ended
Early Plant Retirements (Exelon and Generation)	Jun. 30, 2021
Property, Plant and Equipment [Abstract]
Early Plant Retirements (Exelon and Generation)	Early Plant Retirements (Exelon and Generation)Exelon and Generation continuously evaluate factors that affect the current and expected economic value of Generation’s plants, including, but not limited to: market power prices, results of capacity auctions, potential legislative and regulatory solutions to ensure plants are fairly compensated for benefits they provide through their carbon-free emissions, reliability, or fuel security, and the impact of potential rules from the EPA requiring reduction of carbon and other emissions and the efforts of states to implement those final rules. The precise timing of an early retirement date for any plant, and the resulting financial statement impacts, may be affected by many factors, including the status of potential regulatory or legislative solutions, results of any transmission system reliability study assessments, the nature of any co-owner requirements and stipulations, and NDT fund requirements for nuclear plants, among other factors. However, the earliest retirement date for any plant would usually be the first year in which the unit does not have capacity or other obligations, and where applicable, just prior to its next scheduled nuclear refueling outage. Nuclear Generation In 2015 and 2016, Generation identified the Clinton and Quad Cities nuclear plants in Illinois, Ginna and Nine Mile Point nuclear plants in New York, and TMI nuclear plant in Pennsylvania as having the greatest risk of early retirement based on economic valuation and other factors. In 2017, PSEG made public similar financial challenges facing its New Jersey nuclear plants, including Salem, of which Generation owns a 42.59% ownership interest. PSEG is the operator of Salem and also has the decision-making authority to retire Salem. Assuming the continued effectiveness of the Illinois ZES, New Jersey ZEC program, and the New York CES, Generation and CENG, through its ownership of Ginna and Nine Mile Point, no longer consider Clinton, Quad Cities, Salem, Ginna, or Nine Mile Point to be at heightened risk for early retirement. However, to the extent the Illinois ZES, New Jersey ZEC program, or the New York CES do not operate as expected over their full terms, each of these plants, in addition to FitzPatrick, would be at heightened risk for early retirement, which could have a material impact on Exelon’s and Generation’s future financial statements. In addition, FERC’s December 19, 2019 order on the MOPR in PJM may undermine the continued effectiveness of the Illinois ZES and the New Jersey ZEC program unless PJM adopts further changes to the MOPR or Illinois and New Jersey implement an FRR mechanism under which the Generation plants in these states would be removed from PJM’s capacity auction. At the direction of the PJM Board of Managers, PJM and its stakeholders are considering MOPR reforms to ensure that the capacity market rules respect and accommodate state resource preferences such as the ZEC programs, which PJM filed at FERC on July 30, 2021. See Note 3 - Regulatory Matters for additional information on the New Jersey ZEC program, Note 3 — Regulatory Matters of the 2020 Form 10-K for additional information on the Illinois ZES, New York CES and FERC's December 19, 2019 order on the MOPR in PJM. We cannot predict whether or when FERC will act on PJM's proposed changes. On August 27, 2020, Generation announced that it intends to permanently cease generation operations at Byron in September 2021 and at Dresden in November 2021. The current NRC licenses for Byron Units 1 and 2 expire in 2044 and 2046, respectively, and the licenses for Dresden Units 2 and 3 expire in 2029 and 2031, respectively. Neither of these nuclear plants cleared in PJM’s capacity auction for the 2022-2023 planning year held in May 2021. Generation’s Braidwood and LaSalle nuclear plants in Illinois are also showing increased signs of economic distress, in a market that does not currently compensate them for their unique contribution to grid resiliency and their ability to produce large amounts of energy without carbon and air pollution. While all of Braidwood's and LaSalle's capacity did clear in the 2022-2023 planning year auction, Generation has become increasingly concerned about the economic viability of these plants as well in a landscape where energy market prices remain depressed and energy market rules remain fatally flawed. As a result of the decision to early retire Byron and Dresden, Exelon and Generation recognized certain one-time charges in the third and fourth quarters of 2020 related to materials and supplies inventory reserve adjustments, employee-related costs including severance benefit costs further discussed below, and construction work-in-progress impairments, among other items. In addition, as a result of the decisions to early retire Byron and Dresden, there are ongoing annual financial impacts stemming from shortening the expected economic useful lives of these nuclear plants primarily related to accelerated depreciation of plant assets (including any ARC), accelerated amortization of nuclear fuel, and changes in ARO accretion expense associated with the changes in decommissioning timing and cost assumptions to reflect an earlier retirement date. The total impact for the three and six months ended June 30, 2021 on Exelon's and Generation's Consolidated Statements of Operations and Comprehensive Income is summarized in the table below. Income statement expense (pre-tax) Three Months Ended June 30, 2021 (a) Six Months Ended June 30, 2021 (a) Depreciation and amortization Accelerated depreciation (a) $ 611 $ 1,230 Accelerated nuclear fuel amortization 52 106 Operating and maintenance Other charges 2 4 Contractual offset (b) (166) (391) Total $ 499 $ 949 _________ (a) Includes the accelerated depreciation of plant assets including any ARC. (b) Reflects contractual offset for ARO accretion and ARC depreciation and excludes any changes in earnings in the NDT funds. Decommissioning-related impacts were not offset for the Byron units starting in the second quarter of 2021 due to the inability to recognize a regulatory asset at ComEd. Based on the regulatory agreement with the ICC, decommissioning-related activities are offset within Exelon's and Generation's Consolidated Statements of Operations and Comprehensive Income as long as the net cumulative decommissioning-related activities result in a regulatory liability at ComEd. The offset resulted in an equal adjustment to the noncurrent payables to ComEd at Generation and an adjustment to the regulatory liabilities at ComEd. See Note 8 - Nuclear Decommissioning for additional information. Severance benefit costs will be provided to employees impacted by the early retirements of Byron and Dresden, to the extent they are not redeployed to other nuclear plants. In 2020, Exelon and Generation recorded estimated severance expense of $81 million within Operating and maintenance expense in their Consolidated Statements of Operations and Comprehensive Income. The severance liability was $81 million as of June 30, 2021 on Exelon's and Generation's Consolidated Balance Sheets. The final amount of severance benefit costs will depend on the specific employees severed. The following table provides the balance sheet amounts as of June 30, 2021 for Exelon's and Generation's significant assets and liabilities associated with the Braidwood and LaSalle nuclear plants. Current depreciation provisions are based on the estimated useful lives of these nuclear generating stations, which reflect the first renewal of the operating licenses. Braidwood LaSalle Total Asset Balances Materials and supplies inventory, net $ 82 $ 105 $ 187 Nuclear fuel inventory, net 196 244 440 Completed plant, net 1,380 1,610 2,990 Construction work in progress 30 12 42 Liability Balances Asset retirement obligation (585) (975) (1,560) NRC License First Renewal Term 2046 (Unit 1) 2042 (Unit 1) 2047 (Unit 2) 2043 (Unit 2) Exelon continues to work with stakeholders on state policy solutions, while also advocating for broader market reforms at the regional and federal level. The absence of such solutions or reforms could result in future impairments of the Midwest asset group, or accelerated depreciation for specific plants over their shortened estimated useful lives, both of which could have a material unfavorable impact on Exelon's and Generation's future results of operations. Other Generation In March 2018, Generation notified ISO-NE of its plans to early retire, among other assets, the Mystic Generating Station's units 8 and 9 (Mystic 8 and 9) absent regulatory reforms to properly value reliability and regional fuel security. Thereafter, ISO-NE identified Mystic 8 and 9 as being needed to ensure fuel security for the region and entered into a cost of service agreement with these two units for the period between June 1, 2022 - May 31, 2024. The agreement was approved by the FERC in December 2018. On June 10, 2020, Generation filed a complaint with FERC against ISO-NE stating that ISO-NE failed to follow its tariff with respect to its evaluation of Mystic 8 and 9 for transmission security for the 2024 to 2025 Capacity Commitment Period and that the modifications that ISO-NE made to its unfiled planning procedures to avoid retaining Mystic 8 and 9 should have been filed with FERC for approval. On August 17, 2020, FERC issued an order denying the complaint. As a result, on August 20, 2020, Exelon determined that Generation will permanently cease generation operations at Mystic 8 and 9 at the expiration of the cost of service commitment in May 2024. See Note 3 — Regulatory Matters for additional discussion of Mystic’s cost of service agreement. As a result of the decision to early retire Mystic 8 and 9, there are financial impacts stemming from shortening the expected economic useful life of Mystic 8 and 9 primarily related to accelerated depreciation of plant assets. Exelon and Generation recorded incremental Depreciation and amortization expense of $21 million and $41 million for the three and six months ended June 30, 2021, respectively.

Nuclear Decommissioning (Exelon

Nuclear Decommissioning (Exelon and Generation)	6 Months Ended
Nuclear Decommissioning (Exelon and Generation)	Jun. 30, 2021
Asset Retirement Obligation Disclosure [Abstract]
Nuclear Decommissioning (Exelon and Generation)	Nuclear Decommissioning (Exelon and Generation) Nuclear Decommissioning Asset Retirement Obligations Generation has a legal obligation to decommission its nuclear power plants following the expiration of their operating licenses. To estimate its decommissioning obligation related to its nuclear generating stations for financial accounting and reporting purposes, Generation uses a probability-weighted, discounted cash flow model which, on a unit-by-unit basis, considers multiple outcome scenarios that include significant estimates and assumptions, and are based on decommissioning cost studies, cost escalation rates, probabilistic cash flow models, and discount rates. Generation updates its ARO annually, unless circumstances warrant more frequent updates, based on its review of updated cost studies and its annual evaluation of cost escalation factors and probabilities assigned to various scenarios. The financial statement impact for changes in the ARO, on an individual unit basis, due to the changes in and timing of estimated cash flows generally result in a corresponding change in the unit’s ARC within Property, plant, and equipment on Exelon’s and Generation’s Consolidated Balance Sheets. If the ARO decreases for a Non-Regulatory Agreement unit without any remaining ARC, the corresponding change is recorded as decrease in Operating and maintenance expense within Exelon’s and Generation’s Consolidated Statements of Operations and Comprehensive Income. The following table provides a rollforward of the nuclear decommissioning ARO reflected in Exelon’s and Generation’s Consolidated Balance Sheets from December 31, 2020 to June 30, 2021: Nuclear decommissioning ARO at December 31, 2020 (a) $ 11,922 Accretion expense 249 Costs incurred related to decommissioning plants (39) Nuclear decommissioning ARO at June 30, 2021 (a) $ 12,132 _________ (a) Includes $84 million and $80 million as the current portion of the ARO at June 30, 2021 and December 31, 2020, which is included in Other current liabilities in Exelon’s and Generation’s Consolidated Balance Sheets. On July 28, 2021 Generation submitted PSDAR filings for the Byron and Dresden nuclear units, selecting the SAFSTOR decommissioning approach that allows for up to 60 years in duration, with certain aspects of the specific approach unique to each unit. Based on the approaches selected, and assuming the Byron and Dresden units retire as previously announced in September 2021 and November 2021, respectively, Generation expects to record an incremental increase in the nuclear decommissioning ARO of $650 million to $850 million in the second half of 2021. As discussed further below, contractual offset for the Byron units has been suspended and $275 million to $375 million of this increase in the ARO would result in a pre-tax charge in Exelon’s and Generation’s Consolidated Statements of Operations and Comprehensive Income. NDT Funds Exelon and Generation had NDT funds totaling $15,596 million and $14,599 million at June 30, 2021 and December 31, 2020, respectively. The NDT funds also include $196 million and $134 million for the current portion of the NDT funds at June 30, 2021 and December 31, 2020, respectively, which are included in Other current assets in Exelon's and Generation's Consolidated Balance Sheets. See Note 18 — Supplemental Financial Information for additional information on activities of the NDT funds. Accounting Implications of the Regulatory Agreements with ComEd and PECO Based on the regulatory agreements with the ICC and PAPUC that dictate Generation’s obligations related to the shortfall or excess of NDT funds necessary for decommissioning the former ComEd units on a unit-by-unit basis and the former PECO units in total, decommissioning-related activities net of applicable taxes, including realized and unrealized gains and losses on the NDT funds, depreciation of the ARC, and accretion of the decommissioning obligation, are generally offset within Exelon’s and Generation’s Consolidated Statements of Operations and Comprehensive Income and are recorded by Generation and the corresponding regulated utility as a component of the intercompany and regulatory balances on the balance sheet. For the purposes of making this determination, the decommissioning obligation referred to is different from the calculation used in the NRC minimum funding obligation filings based on NRC guidelines. For the former ComEd units, given no further recovery from ComEd customers is permitted and Generation retains an obligation to ultimately return any unused NDTs to ComEd customers (on a unit-by-unit basis), to the extent the related NDT investment balances are expected to exceed the total estimated decommissioning obligation for each unit, the offset of decommissioning-related activities within the Consolidated Statements of Operations and Comprehensive Income results with Generation recognizing an intercompany payable to ComEd while ComEd records an intercompany receivable from Generation with a corresponding regulatory liability. However, given the asymmetric settlement provision that does not allow for continued recovery from ComEd customers in the event of a shortfall, recognition of a regulatory asset at ComEd is not permissible and accounting for decommissioning-related activities at Generation for that unit would not be offset, and the impact to Exelon’s and Generation’s Consolidated Statements of Operations and Comprehensive Income could be material during such periods. During the second quarter of 2021, a pre-tax charge of $53 million was recorded in Exelon’s and Generation’s Consolidated Statements of Operations and Comprehensive Income for decommissioning-related activities that were not offset for the Byron units due to contractual offset being suspended. Generation believes that additional growth of the NDT funds for the Byron units will ultimately be sufficient to cover the future costs of decommissioning. As of June 30, 2021, decommissioning-related activities for all of the former ComEd units, except for Byron (see discussion above) and Zion (see Note 10 – Asset Retirement Obligations of the Exelon 2020 Form 10-K), are currently offset within Exelon’s and Generation’s Consolidated Statements of Operations and Comprehensive Income. The decommissioning-related activities related to the Non-Regulatory Agreement Units are reflected in Exelon’s and Generation’s Consolidated Statements of Operations and Comprehensive Income. See Note 10 – Asset Retirement Obligations of the Exelon 2020 Form 10-K for additional information, including the former PECO units. NRC Minimum Funding Requirements NRC regulations require that licensees of nuclear generating facilities demonstrate reasonable assurance that funds will be available in specified minimum amounts to decommission the facility at the end of its life. Generation filed its biennial decommissioning funding status report with the NRC on February 24, 2021 for all units, including its shutdown units, except for Zion Station which is included in a separate report to the NRC submitted by ZionSolutions, LLC. The status report demonstrated adequate decommissioning funding assurance as of December 31, 2020 for all units except for Byron Units 1 and 2. Prior to shutdown, Generation will supplement its July 28, 2021 PSDAR filing with decommissioning cost information for Byron Units 1 and 2 and will evaluate the status of funding assurance based on this cost information and updated trust fund values. If required, Generation intends to provide additional funding assurance by the time of shutdown. Generation will file its next decommissioning funding status report with the NRC by March 31, 2022. This report will reflect the status of decommissioning funding assurance as of December 31, 2021 for shutdown units.

Asset Impairments (Exelon and G

Asset Impairments (Exelon and Generation)	6 Months Ended
Asset Impairments (Exelon and Generation)	Jun. 30, 2021
Impairment or Disposal of Tangible Assets Disclosure [Abstract]
Asset Impairments (Exelon and Generation)	Asset Impairments (Exelon and Generation)The Registrants evaluate the carrying value of long-lived assets or asset groups for recoverability whenever events or changes in circumstances indicate that the carrying value of those assets may not be recoverable. Indicators of impairment may include a deteriorating business climate, including, but not limited to, declines in energy prices, condition of the asset, specific regulatory disallowance, or plans to dispose of a long-lived asset significantly before the end of its useful life. The Registrants determine if long-lived assets or asset groups are impaired by comparing the undiscounted expected future cash flows to the carrying value. When the undiscounted cash flow analysis indicates a long-lived asset or asset group is not recoverable, the amount of the impairment loss is determined by measuring the excess of the carrying amount of the long-lived asset or asset group over its fair value. The fair value analysis is primarily based on the income approach using significant unobservable inputs (Level 3) including revenue and generation forecasts, projected capital and maintenance expenditures, and discount rates. A variation in the assumptions used could lead to a different conclusion regarding the recoverability of an asset or asset group and, thus, could potentially result in material future impairments of the Registrant's long-lived assets. New England Asset Group In the third quarter of 2020, in conjunction with the retirement announcement of Mystic Units 8 and 9, Generation, recorded a pre-tax impairment charge of $500 million for the New England asset group. See Note 12 - Asset Impairments of the Exelon 2020 Form 10-K for additional information. In the second quarter of 2021, an overall decline in the asset group's portfolio value suggested that the carrying value of the New England asset group may be impaired. Generation completed a comprehensive review of the estimated undiscounted future cash flows of the New England asset group and concluded that the carrying value was not recoverable and that its fair value was less than its carrying value. As a result, a pre-tax impairment charge of $350 million was recorded in the second quarter of 2021 within Operating and maintenance expense in Exelon’s and Generation’s Consolidated Statements of Operations and Comprehensive Income. Midwest Asset Group Generation will continue to monitor the recoverability of the carrying value of the Midwest asset group as circumstances continue to evolve in Illinois. See Note 7 — Early Plant Retirements for additional information.

Income Taxes (All Registrants)

Income Taxes (All Registrants)	6 Months Ended
Income Taxes (All Registrants)	Jun. 30, 2021
Income Tax Disclosure [Abstract]
Income Taxes (All Registrants)	Income Taxes (All Registrants) Rate Reconciliation The effective income tax rate from continuing operations varies from the U.S. federal statutory rate principally due to the following: Three Months Ended June 30, 2021 Exelon (a) Generation (a) ComEd (a) PECO (a) BGE (a) (b) PHI (a) Pepco (a) DPL (a) ACE (a) U.S. Federal statutory rate 21.0% 21.0% 21.0% 21.0% 21.0% 21.0% 21.0% 21.0% 21.0% Increase (decrease) due to: State income taxes, net of Federal income tax benefit 1.4 (1.3) 8.0 (2.9) (12.5) 2.4 (2.1) 7.0 8.1 Qualified NDT fund income 17.9 85.2 — — — — — — — Amortization of investment tax credit, including deferred taxes on basis difference — (1.8) (0.1) — (0.1) (0.1) — (0.2) (0.2) Plant basis differences (3.1) — (0.7) (12.5) (2.3) (1.1) (1.5) (0.7) (0.6) Production tax credits and other credits (1.9) (13.0) (0.8) — (3.6) (0.8) (0.7) (0.9) (0.6) Noncontrolling interests (0.9) (4.2) — — — — — — — Excess deferred tax amortization (10.4) — (7.0) (3.3) (17.5) (22.3) (19.0) (21.9) (28.2) Other (10.6) 2.8 (1.1) (0.4) (6.6) (1.3) (1.9) (1.1) (2.3) Effective income tax rate 13.4% 88.7% 19.3% 1.9% (21.6)% (2.2)% (4.2)% 3.2% (2.8)% Three Months Ended June 30, 2020 Exelon (a) Generation (a) ComEd (c) PECO (d) BGE (d) PHI (d) Pepco (d) DPL (e) ACE (e) U.S. Federal statutory rate 21.0% 21.0% 21.0% 21.0% 21.0% 21.0% 21.0% 21.0% 21.0% Increase (decrease) due to: State income taxes, net of Federal income tax benefit 3.8 3.1 (131.7) (9.7) 3.8 (25.8) 2.1 6.7 7.2 Qualified NDT fund income 18.8 17.3 — — — — — — — Deferred Prosecution Agreement payments 5.3 — (288.3) — — — — — — Amortization of investment tax credit, including deferred taxes on basis difference (0.6) (0.5) 2.9 — (0.2) (2.2) (0.1) 0.5 0.3 Plant basis differences (1.6) — 2.4 (23.6) (13.4) (44.7) (3.9) (1.1) 10.0 Production tax credits and other credits (1.4) (1.2) 3.3 — (1.0) (0.7) (0.1) 0.1 — Noncontrolling interests 0.1 0.1 — — — — — — — Excess deferred tax amortization (15.5) — 116.0 (4.8) (137.9) (1,358.5) (89.0) 284.0 174.5 Tax Settlements (1.9) (1.8) — — — — — — — Other (f) (0.4) 0.3 (32.3) (4.8) (1.7) 168.0 (2.7) (0.1) 7.0 Effective income tax rate 27.6% 38.3% (306.7)% (21.9)% (129.4)% (1,242.9)% (72.7)% 311.1% 220.0% __________ (a) Positive percentages represent income tax expense. Negative percentages represent income tax benefit. (b) For BGE, the income tax benefit is primarily due to the Maryland multi-year plan which resulted in the acceleration of certain income tax benefits. (c) ComEd recognized a loss before income taxes for the three months ended June 30, 2020. As a result, negative percentages represent income tax expense. The higher effective tax rate is primarily related to the nondeductible Deferred Prosecution Agreement payments. (d) At PECO, BGE, PHI, and Pepco, negative percentages represent an income tax benefit. At PECO, the lower effective tax rate is primarily related to an increase in plant basis differences attributable to storm repairs. At BGE, PHI, and Pepco, the lower effective tax rate is primarily attributable to accelerated amortization of transmission related deferred income tax regulatory liabilities as a result of regulatory settlements. (e) DPL and ACE recognized a loss before income taxes for the three months ended June 30, 2020. As a result, positive percentages represent an income tax benefit. At DPL and ACE, the higher effective tax rate is primarily attributable to accelerated amortization of transmission related deferred income tax regulatory liabilities as a result of regulatory settlements. (f) For Exelon, "Other" is primarily driven by the reversal of the consolidating income tax adjustment recorded at Exelon Corporate in the first quarter of 2021 that was required pursuant to GAAP interim reporting guidance. Six Months Ended June 30, 2021 Exelon (a) Generation (b) ComEd (a) PECO (a)(d) BGE (a)(c) PHI (a) Pepco (a) DPL (a) ACE (a) U.S. Federal statutory rate 21.0% 21.0% 21.0% 21.0% 21.0% 21.0% 21.0% 21.0% 21.0% Increase (decrease) due to: State income taxes, net of Federal income tax benefit (12.6) 5.3 7.4 (2.1) (10.5) 4.2 1.5 6.6 7.8 Qualified NDT fund income 56.2 (18.3) — — — — — — — Amortization of investment tax credit, including deferred taxes on basis difference (2.5) 0.7 (0.1) — (0.1) (0.1) — (0.2) (0.2) Plant basis differences (15.7) — (0.6) (11.3) (1.6) (1.3) (1.8) (0.7) (0.7) Production tax credits and other credits (11.0) 2.9 (0.5) — (0.9) (0.5) (0.5) (0.4) (0.5) Noncontrolling interests (2.5) 0.8 — — — — — — — Excess deferred tax amortization (50.9) — (7.0) (3.3) (15.9) (20.8) (17.2) (19.7) (28.3) Other (e) 38.5 (3.9) (2.3) (0.1) (1.0) (0.7) (0.8) (0.1) (1.1) Effective income tax rate 20.5% 8.5% 17.9% 4.2% (9.0)% 1.8% 2.2% 6.5% (2.0)% Six Months Ended June 30, 2020 Exelon (a) Generation (a) ComEd (a)(g) PECO (a)(d) BGE (a)(h) PHI (a)(h) Pepco (a)(h) DPL (a)(h) ACE (i) U.S. Federal statutory rate 21.0% 21.0% 21.0% 21.0% 21.0% 21.0% 21.0% 21.0% 21.0% Increase (decrease) due to: State income taxes, net of Federal income tax benefit 6.7 7.2 19.1 (1.6) 5.6 4.3 3.7 6.5 12.4 Qualified NDT fund income (5.7) (16.0) — — — — — — — Deferred Prosecution Agreement payments 4.8 — 22.2 — — — — — — Amortization of investment tax credit, including deferred taxes on basis difference (1.0) (2.3) (0.4) — (0.1) (0.2) (0.1) (0.3) 7.2 Plant basis differences (3.7) — (1.4) (11.0) (2.0) (3.5) (2.7) (0.6) 146.2 Production tax credits and other credits (2.2) (5.5) (0.4) — (0.2) (0.1) (0.1) — 0.7 Noncontrolling interests 1.1 3.2 — — — — — — — Excess deferred tax amortization (20.9) — (20.2) (3.3) (16.1) (80.3) (41.6) (72.9) 2,613.8 Tax Settlements (f) (9.3) (26.1) — — — — — — — Other 0.7 (0.3) 3.5 (0.3) (0.6) (1.5) (1.3) 0.8 398.7 Effective income tax rate (8.5)% (18.8)% 43.4% 4.8% 7.6% (60.3)% (21.1)% (45.5)% 3,200.0% __________ (a) Positive percentages represent income tax expense. Negative percentages represent income tax benefit. (b) Generation recognized a loss before income taxes for the six months ended June 30, 2021. As a result, positive percentages represent an income tax benefit for the period presented. (c) For BGE, the income tax benefit is primarily due to the Maryland multi-year plan which resulted in the acceleration of certain income tax benefits. (d) For PECO, the lower effective tax rate is primarily attributable to plant basis differences attributable to tax repairs. (e) For Exelon, "Other" is primarily driven by the consolidating income tax adjustment recorded at Exelon Corporate in the first quarter of 2021 that was required pursuant to GAAP interim reporting guidance. This incremental expense will reverse by year-end and will not have an impact on annual results. (f) Exelon's and Generation’s unrecognized federal and state tax benefits decreased in the first quarter of 2020 by approximately $411 million due to the settlement of a federal refund claim with IRS Appeals. The recognition of these tax benefits resulted in an increase to Exelon's and Generation’s net income of $76 million and $73 million, respectively, in the first quarter of 2020, reflecting a decrease to Exelon's and Generation's income tax expense of $67 million. (g) At ComEd, the higher effective tax rate is primarily related to the nondeductible Deferred Prosecution Agreement payments. (h) At BGE, PHI, Pepco, and DPL, the lower effective tax rate is primarily attributable to accelerated amortization of transmission related deferred income tax regulatory liabilities as a result of regulatory settlements. (i) ACE recognized a loss before income taxes for the six months ended June 30, 2020. As a result, a positive percentage at ACE represents an income tax benefit for the period presented. At ACE, the higher effective tax rate is primarily attributable to accelerated amortization of transmission related deferred income tax regulatory liabilities as a result of regulatory settlements. Unrecognized Tax Benefits PHI and ACE have the following unrecognized tax benefits as of June 30, 2021 and December 31, 2020. Exelon's, Generation's, ComEd's, PECO's, BGE's, Pepco's, and DPL's amounts are not material. PHI ACE June 30, 2021 $ 54 $ 16 December 31, 2020 52 15 Reasonably possible the total amount of unrecognized tax benefits could significantly increase or decrease within 12 months after the reporting date As of June 30, 2021, ACE has approximately $14 million of unrecognized state tax benefits that could significantly decrease within the 12 months after the reporting date based on the outcome of pending court cases involving other taxpayers. The unrecognized tax benefit, if recognized, may be included in future base rates and that portion would have no impact to the effective tax rate.

Retirement Benefits (All Regist

Retirement Benefits (All Registrants)	6 Months Ended
Retirement Benefits (All Registrants)	Jun. 30, 2021
Retirement Benefits [Abstract]
Retirement Benefits (All Registrants)	Retirement Benefits (All Registrants) Defined Benefit Pension and OPEB During the first quarter of 2021, Exelon received an updated valuation of its pension and OPEB to reflect actual census data as of January 1, 2021. This valuation resulted in an increase to the pension obligations of $33 million and a decrease to the OPEB obligations of $9 million. Additionally, accumulated other comprehensive loss increased by $1 million (after-tax) and regulatory assets and liabilities increased by $21 million and $1 million, respectively. The majority of the 2021 pension benefit cost for the Exelon-sponsored plans is calculated using an expected long-term rate of return on plan assets of 7.00% and a discount rate of 2.58%. The majority of the 2021 OPEB cost is calculated using an expected long-term rate of return on plan assets of 6.46% for funded plans and a discount rate of 2.51%. A portion of the net periodic benefit cost for all plans is capitalized within the Consolidated Balance Sheets. The following table presents the components of Exelon's net periodic benefit costs, prior to capitalization, for the three and six months ended June 30, 2021 and 2020. Pension Benefits OPEB Three Months Ended June 30, Three Months Ended June 30, 2021 2020 2021 2020 Components of net periodic benefit cost: Service cost $ 111 $ 96 $ 20 $ 22 Interest cost 160 190 28 39 Expected return on assets (333) (318) (39) (40) Amortization of: Prior service cost (credit) — 1 (9) (31) Actuarial loss 149 128 10 12 Settlement charges 4 6 — — Net periodic benefit cost $ 91 $ 103 $ 10 $ 2 Pension Benefits OPEB Six Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 Components of net periodic benefit cost: Service cost $ 220 $ 193 $ 40 $ 45 Interest cost 320 379 57 77 Expected return on assets (667) (636) (79) (81) Amortization of: Prior service cost (credit) 1 2 (17) (62) Actuarial loss 299 256 19 24 Curtailment benefits — — (1) — Settlement charges 4 6 — — Net periodic benefit cost $ 177 $ 200 $ 19 $ 3 The amounts below represent the Registrants' allocated pension and OPEB costs. For Exelon, the service cost component is included in Operating and maintenance expense and Property, plant, and equipment, net while the non-service cost components are included in Other, net and Regulatory assets. For Generation and the Utility Registrants, the service cost and non-service cost components are included in Operating and maintenance expense and Property, plant, and equipment, net in their consolidated financial statements. Three Months Ended June 30, Six Months Ended June 30, Pension and OPEB Costs 2021 2020 2021 2020 Exelon $ 101 $ 105 $ 196 $ 203 Generation 30 32 56 59 ComEd 32 28 64 57 PECO 2 1 4 3 BGE 16 16 31 31 PHI 12 18 24 35 Pepco 2 4 3 7 DPL 1 2 1 4 ACE 3 3 5 7 Defined Contribution Savings Plans The Registrants participate in various 401(k) defined contribution savings plans that are sponsored by Exelon. The plans are qualified under applicable sections of the IRC and allow employees to contribute a portion of their pre-tax and/or after-tax income in accordance with specified guidelines. All Registrants match a percentage of the employee contributions up to certain limits. The following table presents the matching contributions to the savings plans for the three and six months ended June 30, 2021 and 2020, respectively. Three Months Ended June 30, Six Months Ended June 30, Savings Plans Matching Contributions 2021 2020 2021 2020 Exelon $ 36 $ 34 $ 69 $ 67 Generation 13 14 26 27 ComEd 10 9 18 16 PECO 3 2 6 5 BGE 2 2 4 4 PHI 4 3 7 6 Pepco 1 1 2 2 DPL 1 — 2 1 ACE 1 1 1 1

Derivative Financial Instrument

Derivative Financial Instruments (All Registrants)	6 Months Ended
Derivative Financial Instruments (All Registrants)	Jun. 30, 2021
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Financial Instruments (All Registrants)	Derivative Financial Instruments (All Registrants) The Registrants use derivative instruments to manage commodity price risk, interest rate risk, and foreign exchange risk related to ongoing business operations. Authoritative guidance requires that derivative instruments be recognized as either assets or liabilities at fair value, with changes in fair value of the derivative recognized in earnings immediately. Other accounting treatments are available through special election and designation, provided they meet specific, restrictive criteria both at the time of designation and on an ongoing basis. These alternative permissible accounting treatments include NPNS, cash flow hedges, and fair value hedges. All derivative economic hedges related to commodities, referred to as economic hedges, are recorded at fair value through earnings at Generation and are offset by a corresponding regulatory asset or liability at ComEd. For all NPNS derivative instruments, accounts receivable or accounts payable are recorded when derivatives settle and revenue or expense is recognized in earnings as the underlying physical commodity is sold or consumed. Authoritative guidance about offsetting assets and liabilities requires the fair value of derivative instruments to be shown in the Combined Notes to Consolidated Financial Statements on a gross basis, even when the derivative instruments are subject to legally enforceable master netting agreements and qualify for net presentation in the Consolidated Balance Sheets. A master netting agreement is an agreement between two counterparties that may have derivative and non-derivative contracts with each other providing for the net settlement of all referenced contracts via one payment stream, which takes place as the contracts deliver, when collateral is requested or in the event of default. In the tables below, which present fair value balances, Generation’s energy-related economic hedges and proprietary trading derivatives are shown gross. The impact of the netting of fair value balances with the same counterparty that are subject to legally enforceable master netting agreements, as well as netting of cash collateral, including margin on exchange positions, is aggregated in the collateral and netting columns. Generation’s and ComEd’s use of cash collateral is generally unrestricted unless Generation or ComEd are downgraded below investment grade. Cash collateral held by PECO, BGE, Pepco, DPL, and ACE must be deposited in an unaffiliated major U.S. commercial bank or foreign bank with a U.S. branch office that meet certain qualifications. Commodity Price Risk (All Registrants) Each of the Registrants employ established policies and procedures to manage their risks associated with market fluctuations in commodity prices by entering into physical and financial derivative contracts, including swaps, futures, forwards, options, and short-term and long-term commitments to purchase and sell energy and commodity products. The Registrants believe these instruments, which are either determined to be non-derivative or classified as economic hedges, mitigate exposure to fluctuations in commodity prices. Generation. To the extent the amount of energy Generation produces differs from the amount of energy it has contracted to sell, Exelon and Generation are exposed to market fluctuations in the prices of electricity, fossil fuels, and other commodities. Within Exelon, Generation has the most exposure to commodity price risk. As such, Generation uses a variety of derivative and non-derivative instruments to manage the commodity price risk of its electric generation facilities, including power and gas sales, fuel and power purchases, natural gas transportation and pipeline capacity agreements, and other energy-related products marketed and purchased. To manage these risks, Generation may enter into fixed-price derivative or non-derivative contracts to hedge the variability in future cash flows from expected sales of power and gas and purchases of power and fuel. The objectives for executing such hedges include fixing the price for a portion of anticipated future electricity sales at a level that provides an acceptable return. Generation is also exposed to differences between the locational settlement prices of certain economic hedges and the hedged generating units. This price difference is actively managed through other instruments which include derivative congestion products, whose changes in fair value are recognized in earnings each period, and auction revenue rights, which are accounted for on an accrual basis. Additionally, Generation is exposed to certain market risks through its proprietary trading activities. The proprietary trading activities are a complement to Generation’s energy marketing portfolio but represent a small portion of Generation’s overall energy marketing activities and are subject to limits established by Exelon’s RMC. Utility Registrants . The Utility Registrants procure electric and natural gas supply through a competitive procurement process approved by each of the respective state utility commissions. The Utility Registrants’ hedging programs are intended to reduce exposure to energy and natural gas price volatility and have no direct earnings impact as the costs are fully recovered from customers through regulatory-approved recovery mechanisms. The following table provides a summary of the Utility Registrants’ primary derivative hedging instruments, listed by commodity and accounting treatment. Registrant Commodity Accounting Treatment Hedging Instrument ComEd Electricity NPNS Fixed price contracts based on all requirements in the IPA procurement plans. Electricity Changes in fair value of economic hedge recorded to an offsetting regulatory asset or liability (a) 20-year floating-to-fixed energy swap contracts beginning June 2012 based on the renewable energy resource procurement requirements in the Illinois Settlement Legislation of approximately 1.3 million MWhs per year. PECO Electricity NPNS Fixed price contracts for default supply requirements through full requirements contracts. Gas NPNS Fixed price contracts to cover about 10% of planned natural gas purchases in support of projected firm sales. BGE Electricity NPNS Fixed price contracts for all SOS requirements through full requirements contracts. Gas NPNS Fixed price contracts for between 10-20% of forecasted system supply requirements for flowing (i.e., non-storage) gas for the November through March period. Pepco Electricity NPNS Fixed price contracts for all SOS requirements through full requirements contracts. DPL Electricity NPNS Fixed price contracts for all SOS requirements through full requirements contracts. Gas NPNS Fixed and Index priced contracts through full requirements contracts. Changes in fair value of economic hedge recorded to an offsetting regulatory asset or liability (b) Exchange traded future contracts for up to 50% of estimated monthly purchase requirements each month, including purchases for storage injections. ACE Electricity NPNS Fixed price contracts for all BGS requirements through full requirements contracts. __________ (a) See Note 3 - Regulatory Matters of the 2020 Form 10-K for additional information. (b) The fair value of the DPL economic hedge is not material as of June 30, 2021 and December 31, 2020 and is not presented in the fair value tables below. The following table provides a summary of the derivative fair value balances recorded by Exelon, Generation, and ComEd as of June 30, 2021 and December 31, 2020: Exelon Generation ComEd June 30, 2021 Total Economic Proprietary Collateral (a)(b) Netting (a) Subtotal Economic Mark-to-market derivative assets $ 748 $ 6,541 $ 64 $ (241) $ (5,616) $ 748 $ — Mark-to-market derivative assets 438 1,997 10 (92) (1,477) 438 — Total mark-to-market derivative assets 1,186 8,538 74 (333) (7,093) 1,186 — Mark-to-market derivative liabilities (713) (6,075) (54) (177) 5,616 (690) (23) Mark-to-market derivative liabilities (553) (1,739) (7) (42) 1,477 (311) (242) Total mark-to-market derivative liabilities (1,266) (7,814) (61) (219) 7,093 (1,001) (265) Total mark-to-market derivative net assets (liabilities) $ (80) $ 724 $ 13 $ (552) $ — $ 185 $ (265) Exelon Generation ComEd December 31, 2020 Total Economic Proprietary Collateral (a)(b) Netting (a) Subtotal Economic Mark-to-market derivative assets $ 639 $ 2,757 $ 40 $ 103 $ (2,261) $ 639 $ — Mark-to-market derivative assets 554 1,501 4 64 (1,015) 554 — Total mark-to-market derivative assets 1,193 4,258 44 167 (3,276) 1,193 — Mark-to-market derivative liabilities (293) (2,629) (23) 131 2,261 (260) (33) Mark-to-market derivative liabilities (472) (1,335) (2) 118 1,015 (204) (268) Total mark-to-market derivative liabilities (765) (3,964) (25) 249 3,276 (464) (301) Total mark-to-market derivative net assets (liabilities) $ 428 $ 294 $ 19 $ 416 $ — $ 729 $ (301) _________ (a) Exelon and Generation net all available amounts allowed under the derivative authoritative guidance in the balance sheet. These amounts include unrealized derivative transactions with the same counterparty under legally enforceable master netting agreements and cash collateral. In some cases Exelon and Generation may have other offsetting exposures, subject to a master netting or similar agreement, such as trade receivables and payables, transactions that do not qualify as derivatives, letters of credit, and other forms of non-cash collateral. These amounts are not material and not reflected in the table above. (b) Includes $858 million held and $209 million posted of variation margin with the exchanges as of June 30, 2021 and December 31, 2020 respectively. Economic Hedges (Commodity Price Risk) Generation. For the three and six months ended June 30, 2021 and 2020, Exelon and Generation recognized the following net pre-tax commodity mark-to-market gains (losses) which are also located in the Net fair value changes related to derivatives line in the Consolidated Statements of Cash Flows. Three Months Ended Six Months Ended 2021 2020 2021 2020 Income Statement Location Gain (Loss) Gain (Loss) Operating revenues $ (240) $ 24 $ (323) $ 199 Purchased power and fuel 552 63 817 15 Total Exelon and Generation $ 312 $ 87 $ 494 $ 214 In general, increases and decreases in forward market prices have a positive and negative impact, respectively, on Generation’s owned and contracted generation positions that have not been hedged. Generation hedges commodity price risk on a ratable basis over three-year periods. As of June 30, 2021, the percentage of expected generation hedged for the Mid-Atlantic, Midwest, New York, and ERCOT reportable segments is 98%-101% for 2021. Proprietary Trading (Commodity Price Risk) Generation also executes commodity derivatives for proprietary trading purposes. Proprietary trading includes all contracts executed with the intent of benefiting from shifts or changes in market prices as opposed to those executed with the intent of hedging or managing risk. Gains and losses associated with proprietary trading are reported as Operating revenues in Exelon’s and Generation’s Consolidated Statements of Operations and Comprehensive Income and are included in the Net fair value changes related to derivatives line in the Consolidated Statements of Cash Flows. For the three and six months ended June 30, 2021 and 2020, net pre-tax commodity mark-to-market gains and losses for Exelon and Generation were not material. The Utility Registrants do not execute derivatives for proprietary trading purposes. Interest Rate and Foreign Exchange Risk (Exelon and Generation) Generation utilizes interest rate swaps to manage its interest rate exposure and foreign currency derivatives to manage foreign exchange rate exposure associated with international commodity purchases in currencies other than U.S. dollars, both of which are treated as economic hedges. The notional amounts were $629 million and $665 million for Exelon and Generation as of June 30, 2021 and December 31, 2020, respectively. The mark-to-market derivative assets and liabilities as of June 30, 2021 and December 31, 2020 and the mark-to-market gains and losses for the three and six months ended June 30, 2021 and 2020 were not material for Exelon and Generation. Credit Risk (All Registrants) The Registrants would be exposed to credit-related losses in the event of non-performance by counterparties on executed derivative instruments. The credit exposure of derivative contracts, before collateral, is represented by the fair value of contracts at the reporting date. Generation. For commodity derivatives, Generation enters into enabling agreements that allow for payment netting with its counterparties, which reduces Generation’s exposure to counterparty risk by providing for the offset of amounts payable to the counterparty against amounts receivable from the counterparty. Typically, each enabling agreement is for a specific commodity and so, with respect to each individual counterparty, netting is limited to transactions involving that specific commodity product, except where master netting agreements exist with a counterparty that allow for cross product netting. In addition to payment netting language in the enabling agreement, Generation’s credit department establishes credit limits, margining thresholds, and collateral requirements for each counterparty, which are defined in the derivative contracts. Counterparty credit limits are based on an internal credit review process that considers a variety of factors, including the results of a scoring model, leverage, liquidity, profitability, credit ratings by credit rating agencies, and risk management capabilities. To the extent that a counterparty’s margining thresholds are exceeded, the counterparty is required to post collateral with Generation as specified in each enabling agreement. Generation’s credit department monitors current and forward credit exposure to counterparties and their affiliates, both on an individual and an aggregate basis. The following tables provide information on Generation’s credit exposure for all derivative instruments, NPNS, and payables and receivables, net of collateral and instruments that are subject to master netting agreements, as of June 30, 2021. The tables further delineate that exposure by credit rating of the counterparties and provide guidance on the concentration of credit risk to individual counterparties. The amounts in the tables below exclude credit risk exposure from individual retail counterparties, nuclear fuel procurement contracts, and exposure through RTOs, ISOs, NYMEX, ICE, NASDAQ, NGX, and Nodal commodity exchanges. Rating as of June 30, 2021 Total Exposure Before Credit Collateral Credit Collateral (a) Net Exposure Number of Counterparties Greater than 10% of Net Exposure Net Exposure of Counterparties Greater than 10% of Net Exposure Investment grade $ 446 $ 56 $ 390 — $ — Non-investment grade 15 1 14 No external ratings Internally rated — investment grade 134 1 133 Internally rated — non-investment grade 126 35 91 Total $ 721 $ 93 $ 628 — $ — Net Credit Exposure by Type of Counterparty As of June 30, 2021 Financial institutions $ 27 Investor-owned utilities, marketers, power producers 448 Energy cooperatives and municipalities 85 Other 68 Total $ 628 _________ (a) As of June 30, 2021, credit collateral held from counterparties where Generation had credit exposure included $53 million of cash and $40 million of letters of credit. The credit collateral does not include non-liquid collateral. Utility Registrants. The Utility Registrants have contracts to procure electric and natural gas supply that provide suppliers with a certain amount of unsecured credit. If the exposure on the supply contract exceeds the amount of unsecured credit, the suppliers may be required to post collateral. The net credit exposure is mitigated primarily by the ability to recover procurement costs through customer rates. As of June 30, 2021, the Utility Registrants’ counterparty credit risk with suppliers was not material. Credit-Risk-Related Contingent Features (All Registrants) Generation. As part of the normal course of business, Generation routinely enters into physically or financially settled contracts for the purchase and sale of electric capacity, electricity, fuels, emissions allowances, and other energy-related products. Certain of Generation’s derivative instruments contain provisions that require Generation to post collateral. Generation also enters into commodity transactions on exchanges where the exchanges act as the counterparty to each trade. Transactions on the exchanges must adhere to comprehensive collateral and margining requirements. This collateral may be posted in the form of cash or credit support with thresholds contingent upon Generation’s credit rating from each of the major credit rating agencies. The collateral and credit support requirements vary by contract and by counterparty. These credit-risk-related contingent features stipulate that if Generation were to be downgraded or lose its investment grade credit rating (based on its senior unsecured debt rating), it would be required to provide additional collateral. This incremental collateral requirement allows for the offsetting of derivative instruments that are assets with the same counterparty, where the contractual right of offset exists under applicable master netting agreements. In the absence of expressly agreed-to provisions that specify the collateral that must be provided, collateral requested will be a function of the facts and circumstances of the situation at the time of the demand. In this case, Generation believes an amount of several months of future payments (i.e., capacity payments) rather than a calculation of fair value is the best estimate for the contingent collateral obligation, which has been factored into the disclosure below. The aggregate fair value of all derivative instruments with credit-risk related contingent features in a liability position that are not fully collateralized (excluding transactions on the exchanges that are fully collateralized) is detailed in the table below: Credit-Risk Related Contingent Features June 30, 2021 December 31, 2020 Gross fair value of derivative contracts containing this feature (a) $ (2,173) $ (834) Offsetting fair value of in-the-money contracts under master netting arrangements (b) 1,151 537 Net fair value of derivative contracts containing this feature (c) $ (1,022) $ (297) _________ (a) Amount represents the gross fair value of out-of-the-money derivative contracts containing credit-risk related contingent features ignoring the effects of master netting agreements. (b) Amount represents the offsetting fair value of in-the-money derivative contracts under legally enforceable master netting agreements with the same counterparty, which reduces the amount of any liability for which Generation could potentially be required to post collateral. (c) Amount represents the net fair value of out-of-the-money derivative contracts containing credit-risk related contingent features after considering the mitigating effects of offsetting positions under master netting arrangements and reflects the actual net liability upon which any potential contingent collateral obligations would be based. As of June 30, 2021 and December 31, 2020, Exelon and Generation posted or held the following amounts of cash collateral and letters of credit on derivative contracts with external counterparties, after giving consideration to offsetting derivative and non-derivative positions under master netting agreements. June 30, 2021 December 31, 2020 Cash collateral posted $ 67 $ 511 Letters of credit posted 344 226 Cash collateral held 621 110 Letters of credit held 50 40 Additional collateral required in the event of a credit downgrade below investment grade 1,899 1,432 Generation entered into supply forward contracts with certain utilities, including PECO and BGE, with one-sided collateral postings only from Generation. If market prices fall below the benchmark price levels in these contracts, the utilities are not required to post collateral. However, when market prices rise above the benchmark price levels, counterparty suppliers, including Generation, are required to post collateral once certain unsecured credit limits are exceeded. Utility Registrants The Utility Registrants’ electric supply procurement contracts do not contain provisions that would require them to post collateral.

Debt and Credit Agreements (All

Debt and Credit Agreements (All Registrants)	6 Months Ended
Debt and Credit Agreements (All Registrants)	Jun. 30, 2021
Debt Disclosure [Abstract]
Debt and Credit Agreements (All Registrants)	Debt and Credit Agreements (All Registrants) Short-Term Borrowings Exelon Corporate, ComEd, and BGE meet their short-term liquidity requirements primarily through the issuance of commercial paper. Generation and PECO meet their short-term liquidity requirements primarily through the issuance of commercial paper and borrowings from the Exelon intercompany money pool. Pepco, DPL, and ACE meet their short-term liquidity requirements primarily through the issuance of commercial paper and borrowings from the PHI intercompany money pool. PHI Corporate meets its short-term liquidity requirements primarily through the issuance of short-term notes and the Exelon intercompany money pool. The Registrants may use their respective credit facilities for general corporate purposes, including meeting short-term funding requirements and the issuance of letters of credit. Commercial Paper The following table reflects the Registrants' commercial paper programs as of June 30, 2021 and December 31, 2020. PECO and BGE had no commercial paper borrowings as of both June 30, 2021 and December 31, 2020. Outstanding Commercial Average Interest Rate on Commercial Paper Issuer June 30, 2021 December 31, 2020 June 30, 2021 December 31, 2020 Exelon (a) $ 365 $ 1,031 0.17 % 0.25 % Generation — 340 — % 0.27 % ComEd 33 323 0.15 % 0.23 % PHI (b) 332 368 0.17 % 0.24 % Pepco 154 35 0.17 % 0.22 % DPL — 146 — % 0.24 % ACE 178 187 0.18 % 0.25 % __________ (a) Exelon Corporate had no outstanding commercial paper borrowings as of both June 30, 2021 and December 31, 2020. (b) Represents the consolidated amounts of Pepco, DPL, and ACE. See Note 17 – Debt and Credit Agreements of the Exelon 2020 Form 10-K for additional information on the Registrants' credit facilities. Short-Term Loan Agreements On March 23, 2017, Exelon Corporate entered into a term loan agreement for $500 million. The loan agreement was renewed on March 17, 2021 and will expire on March 16, 2022. Pursuant to the loan agreement, loans made thereunder bear interest at a variable rate equal to LIBOR plus 0.65% and all indebtedness thereunder is unsecured. The loan agreement is reflected in Exelon's Consolidated Balance Sheets within Short-term borrowings. On March 24, 2021, Exelon Corporate entered into a 9-month term loan agreement for $200 million. The loan agreement has an expiration of December 24, 2021. Pursuant to the loan agreement, loans made thereunder bear interest at a variable rate equal to LIBOR plus 0.65% and all indebtedness thereunder is unsecured. The loan agreement is reflected in Exelon's Consolidated Balance Sheets within Short-term borrowings. On March 31, 2021, Exelon Corporate entered into a 9-month and 364-day term loan agreement for $150 million each with variable interest rates of LIBOR plus 0.65% and expiration dates of December 31, 2021 and March 30, 2022, respectively. The loan agreements are reflected in Exelon's Consolidated Balance Sheets within Short-term borrowings. On March 19, 2020, Generation entered into a term loan agreement for $200 million. The loan agreement was renewed on March 17, 2021 and will expire on March 16, 2022. Pursuant to the loan agreement, loans made thereunder bear interest at a variable rate equal to LIBOR plus 0.875% and all indebtedness thereunder is unsecured. The loan agreement is reflected in Exelon's and Generation's Consolidated Balance Sheets within Short-term borrowings. On March 31, 2020, Generation entered into a term loan agreement for $300 million. The loan agreement was renewed on March 30, 2021 and will expire on March 29, 2022. Pursuant to the loan agreement, loans made thereunder bear interest at a variable rate equal to LIBOR plus 0.70% and all indebtedness thereunder is unsecured. The loan agreement is reflected in Exelon's and Generation's Consolidated Balance Sheets within Short-term borrowings. On January 25, 2021, ComEd entered into two 90-day term loan agreements for $125 million each with variable interest rates of LIBOR plus 0.50% and LIBOR plus 0.75%, respectively. ComEd repaid the term loans on March 9, 2021. Bilateral Credit Agreements On January 11, 2013, Generation entered into a bilateral credit agreement for $100 million. The agreement was renewed on March 1, 2021 with a maturity date of March 1, 2023. On February 21, 2019, Generation entered into a bilateral credit agreement for $100 million. The agreement was renewed on March 31, 2021 with a maturity date of March 31, 2022. On January 5, 2016, Generation entered into a bilateral credit agreement for $150 million. The agreement was renewed on April 2, 2021 with a maturity date of April 5, 2023. See Note 17 – Debt and Credit Agreements of the Exelon 2020 Form 10-K for additional information on Generation's bilateral credit agreements. Credit Agreements On July 15, 2021, each of the Registrants' respective syndicated revolving credit facilities had their maturity dates extended to May 26, 2024. Long-Term Debt Issuance of Long-Term Debt During the six months ended June 30, 2021, the following long-term debt was issued: Company Type Interest Rate Maturity Amount Use of Proceeds Exelon Long-Term Software License Agreements 3.62 % December 1, 2025 $ 4 Procurement of software licenses. Generation West Medway II LIBOR + 3% (a) March 31, 2026 150 Funding for general corporate purposes. Generation Energy Efficiency Project Financing (b) 2.53 % August 31, 2021 1 Funding to install energy conservation measures for the Fort AP Hill project. ComEd First Mortgage Bonds, Series 130 3.13 % March 15, 2051 700 Repay a portion of outstanding commercial paper obligations and two outstanding term loans, and to fund other general corporate purposes. PECO First and Refunding Mortgage Bonds 3.05 % March 15, 2051 375 Funding for general corporate purposes. BGE Senior Notes 2.25 % June 15, 2031 600 Repay a portion of outstanding commercial paper obligations, repay existing indebtedness, and to fund other general corporate purposes. Pepco (c) First Mortgage Bonds 2.32 % March 30, 2031 150 Repay existing indebtedness and for general corporate purposes. DPL First Mortgage Bonds 3.24 % March 30, 2051 125 Repay existing indebtedness and for general corporate purposes. ACE First Mortgage Bonds 2.30 % March 15, 2031 350 Refinance existing indebtedness, repay outstanding commercial paper obligations, and for general corporate purposes. __________ (a) The nonrecourse debt has an average blended interest rate. (b) For Energy Efficiency Project Financing, the maturity dates represent the expected date of project completion, upon which the respective customer assumes the outstanding debt. (c) On March 30, 2021, Pepco entered into a purchase agreement of First Mortgage Bonds of $125 million at 3.29% due on September 28, 2051. The closing date of the issuance is expected to occur in September 2021. Debt Covenants As of June 30, 2021, the Registrants are in compliance with debt covenants. Nonrecourse Debt Exelon and Generation have issued nonrecourse debt financing. Borrowings under these agreements are secured by the assets and equity of each respective project. The lenders do not have recourse against Exelon or Generation in the event of a default. West Medway II, LLC. On May 13, 2021, West Medway II, LLC (West Medway II), an indirect subsidiary of Generation, entered into a financing agreement for a $150 million nonrecourse senior secured term loan credit facility with a maturity date of March 31, 2026. The term loan bears interest at an average blended interest rate of LIBOR plus 3%, paid quarterly. In addition to the financing, West Medway II, entered into interest rate swaps with an initial notional amount of $113 million at an interest rate of 0.61%, paid quarterly, to manage a portion of the interest rate exposure in connection with financing. The net proceeds were distributed to Generation for general corporate purposes. Generation’s interests in West Medway II, were pledged as collateral for this financing. As of June 30, 2021 approximately $150 million was outstanding. See Note 17 – Debt and Credit Agreements of the Exelon 2020 Form 10-K for additional information on nonrecourse debt and Note 12 – Derivative Financial Instruments for additional information on interest rate swaps.

Fair Value of Financial Assets

Fair Value of Financial Assets and Liabilities (All Registrants)	6 Months Ended
	Jun. 30, 2021
Fair Value Disclosures [Abstract]
Fair Value of Financial Assets and Liabilities (All Registrants)	Fair Value of Financial Assets and Liabilities (All Registrants) Exelon measures and classifies fair value measurements in accordance with the hierarchy as defined by GAAP. The hierarchy prioritizes the inputs to valuation techniques used to measure fair value into three levels as follows: • Level 1 - quoted prices (unadjusted) in active markets for identical assets or liabilities that the Registrants have the ability to liquidate as of the reporting date. • Level 2 - inputs other than quoted prices included within Level 1 that are directly observable for the asset or liability or indirectly observable through corroboration with observable market data. • Level 3 - unobservable inputs, such as internally developed pricing models or third-party valuations for the asset or liability due to little or no market activity for the asset or liability. Fair Value of Financial Liabilities Recorded at Amortized Cost The following tables present the carrying amounts and fair values of the Registrants’ short-term liabilities, long-term debt, SNF obligation, and trust preferred securities (long-term debt to financing trusts or junior subordinated debentures) as of June 30, 2021 and December 31, 2020. The Registrants have no financial liabilities classified as Level 1. The carrying amounts of the Registrants’ short-term liabilities as presented on their Consolidated Balance Sheets are representative of their fair value (Level 2) because of the short-term nature of these instruments. June 30, 2021 December 31, 2020 Carrying Amount Fair Value Carrying Amount Fair Value Level 2 Level 3 Total Level 2 Level 3 Total Long-Term Debt, including amounts due within one year (a) Exelon $ 38,710 $ 40,956 $ 3,189 $ 44,145 $ 36,912 $ 40,688 $ 3,064 $ 43,752 Generation 6,178 5,776 1,145 6,921 6,087 5,648 1,208 6,856 ComEd 9,675 11,407 — 11,407 8,983 11,117 — 11,117 PECO 4,125 4,722 50 4,772 3,753 4,553 50 4,603 BGE 4,259 4,748 — 4,748 3,664 4,366 — 4,366 PHI 7,369 6,048 1,994 8,042 7,006 6,099 1,806 7,905 Pepco 3,318 3,240 860 4,100 3,165 3,336 748 4,084 DPL 1,804 1,434 556 1,990 1,677 1,484 455 1,939 ACE 1,515 1,117 578 1,695 1,413 1,018 602 1,620 Long-Term Debt to Financing Trusts (a) Exelon $ 390 $ — $ 482 $ 482 $ 390 $ — $ 467 $ 467 ComEd 205 — 253 253 205 — 246 246 PECO 184 — 229 229 184 — 221 221 SNF Obligation Exelon $ 1,209 $ 995 $ — $ 995 $ 1,208 $ 909 $ — $ 909 Generation 1,209 995 — 995 1,208 909 — 909 __________ (a) Includes unamortized debt issuance costs which are not fair valued. Recurring Fair Value Measurements The following tables present assets and liabilities measured and recorded at fair value in the Registrants' Consolidated Balance Sheets on a recurring basis and their level within the fair value hierarchy as of June 30, 2021 and December 31, 2020: Exelon and Generation Exelon Generation As of June 30, 2021 Level 1 Level 2 Level 3 Not subject to leveling Total Level 1 Level 2 Level 3 Not subject to leveling Total Assets Cash equivalents (a) $ 1,167 $ — $ — $ — $ 1,167 $ 162 $ — $ — $ — $ 162 NDT fund investments Cash equivalents (b) 552 75 — — 627 552 75 — — 627 Equities 4,770 1,720 — 1,671 8,161 4,770 1,720 — 1,671 8,161 Fixed income Corporate debt (c) — 1,146 285 — 1,431 — 1,146 285 — 1,431 U.S. Treasury and agencies 2,052 39 — — 2,091 2,052 39 — — 2,091 Foreign governments — 51 — — 51 — 51 — — 51 State and municipal debt — 28 — — 28 — 28 — — 28 Other 32 31 — 1,113 1,176 32 31 — 1,113 1,176 Fixed income subtotal 2,084 1,295 285 1,113 4,777 2,084 1,295 285 1,113 4,777 Private credit — — 176 607 783 — — 176 607 783 Private equity — — — 580 580 — — — 580 580 Real estate — — — 762 762 — — — 762 762 NDT fund investments subtotal (d)(e) 7,406 3,090 461 4,733 15,690 7,406 3,090 461 4,733 15,690 Rabbi trust investments Cash equivalents 65 — — — 65 4 — — — 4 Mutual funds 99 — — — 99 33 — — — 33 Fixed income — 11 — — 11 — — — — — Life insurance contracts — 94 34 — 128 — 31 — — 31 Rabbi trust investments subtotal 164 105 34 — 303 37 31 — — 68 Investments in equities (f) 327 — — — 327 327 — — — 327 Commodity derivative assets Economic hedges 1,781 3,917 2,840 — 8,538 1,781 3,917 2,840 — 8,538 Proprietary trading — 62 12 — 74 — 62 12 — 74 Effect of netting and allocation of collateral (g)(h) (1,411) (3,502) (2,513) — (7,426) (1,411) (3,502) (2,513) — (7,426) Commodity derivative assets subtotal 370 477 339 — 1,186 370 477 339 — 1,186 DPP consideration — 374 — — 374 — 374 — — 374 Exelon Generation As of June 30, 2021 Level 1 Level 2 Level 3 Not subject to leveling Total Level 1 Level 2 Level 3 Not subject to leveling Total Total assets 9,434 4,046 834 4,733 19,047 8,302 3,972 800 4,733 17,807 Liabilities Commodity derivative liabilities Economic hedges (1,245) (3,444) (3,390) — (8,079) (1,245) (3,444) (3,125) — (7,814) Proprietary trading — (45) (16) — (61) — (45) (16) — (61) Effect of netting and allocation of collateral (g)(h) 1,242 3,295 2,337 — 6,874 1,242 3,295 2,337 — 6,874 Commodity derivative liabilities subtotal (3) (194) (1,069) — (1,266) (3) (194) (804) — (1,001) Deferred compensation obligation — (144) — — (144) — (42) — — (42) Total liabilities (3) (338) (1,069) — (1,410) (3) (236) (804) — (1,043) Total net assets (liabilities) $ 9,431 $ 3,708 $ (235) $ 4,733 $ 17,637 $ 8,299 $ 3,736 $ (4) $ 4,733 $ 16,764 Exelon Generation As of December 31, 2020 Level 1 Level 2 Level 3 Not subject to leveling Total Level 1 Level 2 Level 3 Not subject to leveling Total Assets Cash equivalents (a) $ 686 $ — $ — $ — $ 686 $ 124 $ — $ — $ — $ 124 NDT fund investments Cash equivalents (b) 210 95 — — 305 210 95 — — 305 Equities 3,886 2,077 — 1,562 7,525 3,886 2,077 — 1,562 7,525 Fixed income Corporate debt (c) — 1,485 285 — 1,770 — 1,485 285 — 1,770 U.S. Treasury and agencies 1,871 126 — — 1,997 1,871 126 — — 1,997 Foreign governments — 56 — — 56 — 56 — — 56 State and municipal debt — 101 — — 101 — 101 — — 101 Other — 41 — 961 1,002 — 41 — 961 1,002 Fixed income subtotal 1,871 1,809 285 961 4,926 1,871 1,809 285 961 4,926 Private credit — — 212 629 841 — — 212 629 841 Private equity — — — 504 504 — — — 504 504 Real estate — — — 679 679 — — — 679 679 NDT fund investments subtotal (d)(e) 5,967 3,981 497 4,335 14,780 5,967 3,981 497 4,335 14,780 Rabbi trust investments Cash equivalents 60 — — — 60 4 — — — 4 Mutual funds 91 — — — 91 29 — — — 29 Fixed income — 11 — — 11 — — — — — Life insurance contracts — 87 34 — 121 — 28 — — 28 Rabbi trust investments subtotal 151 98 34 — 283 33 28 — — 61 Investments in equities (f) 195 — — — 195 195 — — — 195 Commodity derivative assets Economic hedges 745 1,914 1,599 — 4,258 745 1,914 1,599 — 4,258 Proprietary trading — 17 27 — 44 — 17 27 — 44 Exelon Generation As of December 31, 2020 Level 1 Level 2 Level 3 Not subject to leveling Total Level 1 Level 2 Level 3 Not subject to leveling Total Effect of netting and allocation of collateral (g)(h) (607) (1,597) (905) — (3,109) (607) (1,597) (905) — (3,109) Commodity derivative assets subtotal 138 334 721 — 1,193 138 334 721 — 1,193 DPP consideration — 639 — — 639 — 639 — — 639 Total assets 7,137 5,052 1,252 4,335 17,776 6,457 4,982 1,218 4,335 16,992 Liabilities Commodity derivative liabilities Economic hedges (682) (1,928) (1,655) — (4,265) (682) (1,928) (1,354) — (3,964) Proprietary trading — (21) (4) — (25) — (21) (4) — (25) Effect of netting and allocation of collateral (g)(h) 540 1,918 1,067 — 3,525 540 1,918 1,067 — 3,525 Commodity derivative liabilities subtotal (142) (31) (592) — (765) (142) (31) (291) — (464) Deferred compensation obligation — (145) — — (145) — (42) — — (42) Total liabilities (142) (176) (592) — (910) (142) (73) (291) — (506) Total net assets $ 6,995 $ 4,876 $ 660 $ 4,335 $ 16,866 $ 6,315 $ 4,909 $ 927 $ 4,335 $ 16,486 __________ (a) Exelon excludes cash of $728 million and $409 million at June 30, 2021 and December 31, 2020, respectively, and restricted cash of $114 million and $59 million at June 30, 2021 and December 31, 2020, respectively, and includes long-term restricted cash of $52 million and $53 million at June 30, 2021 and December 31, 2020, respectively, which is reported in Other deferred debits in the Consolidated Balance Sheets. Generation excludes cash of $407 million and $171 million at June 30, 2021 and December 31, 2020, respectively, and restricted cash of $32 million and $20 million at June 30, 2021 and December 31, 2020, respectively. (b) Includes $103 million and $116 million of cash received from outstanding repurchase agreements at June 30, 2021 and December 31, 2020, respectively, and is offset by an obligation to repay upon settlement of the agreement as discussed in (e) below. (c) Includes investments in equities sold short of $(52) million and $(62) million as of June 30, 2021 and December 31, 2020, respectively, held in an investment vehicle primarily to hedge the equity option component of its convertible debt. (d) Includes derivative assets of less than $1 million and $2 million, which have total notional amounts of $2,016 million and $1,043 million at June 30, 2021 and December 31, 2020, respectively. The notional principal amounts for these instruments provide one measure of the transaction volume outstanding as of the periods ended and do not represent the amount of Exelon and Generation's exposure to credit or market loss. (e) Excludes net liabilities of $94 million and $181 million at June 30, 2021 and December 31, 2020, respectively, which include certain derivative assets that have notional amounts of $137 million and $104 million at June 30, 2021 and December 31, 2020, respectively. These items consist of receivables related to pending securities sales, interest and dividend receivables, repurchase agreement obligations, and payables related to pending securities purchases. The repurchase agreements are generally short-term in nature with durations generally of 30 days or less. (f) Includes equity investments held by Generation which were previously designated as equity investments without readily determinable fair value but are now publicly traded and therefore have readily determinable fair values. The first investment became publicly traded in the fourth quarter of 2020. Generation recorded the fair value of these investments in Other current assets on Exelon's and Generation's Consolidated Balance Sheets based on the quoted market prices of the stocks at June 30, 2021, which resulted in unrealized gains for investments that became publicly traded during 2021 o f $102 million and $220 million within Other, net in Exelon's and Generation's Consolidated Statements of Operations and Comprehensive Income for the three and six months ended June 30, 2021, respectively. (g) Collateral (received) from counterparties, net of collateral paid to counterparties, totaled $(169) million, $(207) million, and $(176) million allocated to Level 1, Level 2, and Level 3 mark-to-market derivatives, respectively, as of June 30, 2021. Collateral (received)/posted from counterparties, net of collateral paid to counterparties, totaled $(67) million, $321 million, and $162 million allocated to Level 1, Level 2, and Level 3 mark-to-market derivatives, respectively, as of December 31, 2020. (h) Includes $858 million held and $209 million posted of variation margin with the exchanges as of June 30, 2021 and December 31, 2020, respectively. As of June 30, 2021, Exelon and Generation have outstanding commitments to invest in private credit, private equity, and real estate investments of approximately $364 million, $224 million, and $320 million, respectively. These commitments will be funded by Generation’s existing NDT funds. Exelon and Generation held investments without readily determinable fair values with carrying amounts of $38 million and $26 million as of June 30, 2021, respectively. Exelon and Generation held investments without readily determinable fair values with carrying amounts of $73 million and $55 million as of December 31, 2020, respectively. Changes in fair value, cumulative adjustments, and impairments were not material for the three and six months ended June 30, 2021 and for the year ended December 31, 2020. ComEd, PECO, and BGE ComEd PECO BGE As of June 30, 2021 Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Assets Cash equivalents (a) $ 264 $ — $ — $ 264 $ 230 $ — $ — $ 230 $ 334 $ — $ — $ 334 Rabbi trust investments Mutual funds — — — — 10 — — 10 14 — — 14 Life insurance contracts — — — — — 15 — 15 — — — — Rabbi trust investments subtotal — — — — 10 15 — 25 14 — — 14 Total assets 264 — — 264 240 15 — 255 348 — — 348 Liabilities Deferred compensation obligation — (9) — (9) — (8) — (8) — (6) — (6) Mark-to-market derivative liabilities (b) — — (265) (265) — — — — — — — — Total liabilities — (9) (265) (274) — (8) — (8) — (6) — (6) Total net assets (liabilities) $ 264 $ (9) $ (265) $ (10) $ 240 $ 7 $ — $ 247 $ 348 $ (6) $ — $ 342 ComEd PECO BGE As of December 31, 2020 Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Assets Cash equivalents (a) $ 285 $ — $ — $ 285 $ 8 $ — $ — $ 8 $ 120 $ — $ — $ 120 Rabbi trust investments Mutual funds — — — — 9 — — 9 10 — — 10 Life insurance contracts — — — — — 13 — 13 — — — — Rabbi trust investments subtotal — — — — 9 13 — 22 10 — — 10 Total assets 285 — — 285 17 13 — 30 130 — — 130 Liabilities Deferred compensation obligation — (8) — (8) — (9) — (9) — (5) — (5) Mark-to-market derivative liabilities (b) — — (301) (301) — — — — — — — — Total liabilities — (8) (301) (309) — (9) — (9) — (5) — (5) Total net assets (liabilities) $ 285 $ (8) $ (301) $ (24) $ 17 $ 4 $ — $ 21 $ 130 $ (5) $ — $ 125 __________ (a) ComEd excludes cash of $44 million and $83 million at June 30, 2021 and December 31, 2020, respectively, and restricted cash of $46 million and $37 million at June 30, 2021 and December 31, 2020, respectively, and includes long-term restricted cash of $43 million at both June 30, 2021 and December 31, 2020, respectively, which is reported in Other deferred debits in the Consolidated Balance Sheets. PECO excludes cash of $154 million and $18 million at June 30, 2021 and December 31, 2020, respectively. BGE excludes cash of $34 million and $24 million at June 30, 2021 and December 31, 2020, respectively, and restricted cash of $3 million and $1 million at June 30, 2021 and December 31, 2020, respectively. (b) The Level 3 balance consists of the current and noncurrent liability of $23 million and $242 million, respectively, at June 30, 2021 and $33 million and $268 million, respectively, at December 31, 2020 related to floating-to-fixed energy swap contracts with unaffiliated suppliers. PHI, Pepco, DPL, and ACE As of June 30, 2021 As of December 31, 2020 PHI Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Assets Cash equivalents (a) $ 46 $ — $ — $ 46 $ 86 $ — $ — $ 86 Rabbi trust investments Cash equivalents 59 — — 59 55 — — 55 Mutual funds 14 — — 14 14 — — 14 Fixed income — 11 — 11 — 11 — 11 Life insurance contracts — 26 34 60 — 26 34 60 Rabbi trust investments subtotal 73 37 34 144 69 37 34 140 Total assets 119 37 34 190 155 37 34 226 Liabilities Deferred compensation obligation — (16) — (16) — (17) — (17) Total liabilities — (16) — (16) — (17) — (17) Total net assets $ 119 $ 21 $ 34 $ 174 $ 155 $ 20 $ 34 $ 209 Pepco DPL ACE As of June 30, 2021 Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Assets Cash equivalents (a) $ 28 $ — $ — $ 28 $ 5 $ — $ — $ 5 $ 12 $ — $ — $ 12 Rabbi trust investments Cash equivalents 57 — — 57 — — — — — — — — Fixed income — 2 — 2 — — — — — — — — Life insurance contracts — 26 34 60 — — — — — — — — Rabbi trust investments subtotal 57 28 34 119 — — — — — — — — Total assets 85 28 34 147 5 — — 5 12 — — 12 Liabilities Deferred compensation obligation — (2) — (2) — — — — — — — — Total liabilities — (2) — (2) — — — — — — — — Total net assets $ 85 $ 26 $ 34 $ 145 $ 5 $ — $ — $ 5 $ 12 $ — $ — $ 12 Pepco DPL ACE As of December 31, 2020 Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Assets Cash equivalents (a) $ 35 $ — $ — $ 35 $ — $ — $ — $ — $ 13 $ — $ — $ 13 Rabbi trust investments Cash equivalents 53 — — 53 — — — — — — — — Fixed income — 2 — 2 — — — — — — — — Life insurance contracts — 26 34 60 — — — — — — — — Rabbi trust investments subtotal 53 28 34 115 — — — — — — — — Total assets 88 28 34 150 — — — — 13 — — 13 Liabilities Deferred compensation obligation — (2) — (2) — — — — — — — — Total liabilities — (2) — (2) — — — — — — — — Total net assets $ 88 $ 26 $ 34 $ 148 $ — $ — $ — $ — $ 13 $ — $ — $ 13 __________ (a) PHI excludes cash of $61 million and $74 million at June 30, 2021 and December 31, 2020, respectively, and restricted cash of $5 million and none at June 30, 2021 and December 31, 2020, respectively, and includes long-term restricted cash of $9 million and $10 million at June 30, 2021 and December 31, 2020, respectively, which is reported in Other deferred debits in the Consolidated Balance Sheets. Pepco excludes cash of $17 million and $30 million at June 30, 2021 and December 31, 2020, respectively, and restricted cash of $5 million and none at June 30, 2021 and December 31, 2020, respectively. DPL excludes cash of $17 million and $15 million at June 30, 2021 and December 31, 2020, respectively. ACE excludes cash of $11 million and $17 million at June 30, 2021 and December 31, 2020, respectively, and includes long-term restricted cash of $9 million and $10 million at June 30, 2021 and December 31, 2020, respectively, which is reported in Other deferred debits in the Consolidated Balance Sheets. Reconciliation of Level 3 Assets and Liabilities The following tables present the fair value reconciliation of Level 3 assets and liabilities measured at fair value on a recurring basis during the three and six months ended June 30, 2021 and 2020: Exelon Generation ComEd PHI and Pepco Three Months Ended June 30, 2021 Total NDT Fund Mark-to-Market Total Generation Mark-to-Market Life Insurance Contracts Eliminated in Consolidation Balance as of March 31, 2021 $ 426 $ 479 $ 207 $ 686 $ (295) $ 35 $ — Total realized / unrealized gains (losses) Included in net income (357) 1 (359) (a) (358) — 1 — Included in noncurrent payables to affiliates — 6 — 6 — — (6) Included in regulatory assets 36 — — — 30 (b) — 6 Change in collateral (282) — (282) (282) — — — Purchases, sales, and settlements Purchases 7 1 6 7 — — — Sales 1 — 1 1 — — — Settlements (28) (26) — (26) — (2) — Transfers into Level 3 1 — 1 (c) 1 — — — Transfers out of Level 3 (39) — (39) (c) (39) — — — Balance at June 30, 2021 $ (235) $ 461 $ (465) $ (4) $ (265) $ 34 $ — The amount of total (losses) gains included in income attributed to the change in unrealized gains (losses) related to assets and liabilities as of June 30, 2021 $ (372) $ 1 $ (374) $ (373) $ — $ 1 $ — Exelon Generation ComEd PHI and Pepco Six months ended June 30, 2021 Total NDT Fund Mark-to-Market Total Generation Mark-to-Market Life Insurance Contracts Eliminated in Consolidation Balance as of December 31, 2020 $ 660 $ 497 $ 430 $ 927 $ (301) $ 34 $ — Total realized / unrealized gains (losses) Included in net income (632) 2 (636) (a) (634) — 2 — Included in noncurrent payables to affiliates — 7 — 7 — — (7) Included in regulatory assets 43 — — — 36 (b) — 7 Change in collateral (338) — (338) (338) — — — Purchases, sales, and settlements Purchases 115 1 114 115 — — — Sales 1 — 1 1 — — — Settlements (48) (46) — (46) — (2) — Transfers into Level 3 1 — 1 (c) 1 — — — Transfers out of Level 3 (37) — (37) (c) (37) — — — Balance as of June 30, 2021 $ (235) $ 461 $ (465) $ (4) $ (265) $ 34 $ — The amount of total (losses) gains included in income attributed to the change in unrealized gains (losses) related to assets and liabilities as of June 30, 2021 $ (518) $ 2 $ (522) $ (520) $ — $ 2 $ — Exelon Generation ComEd PHI and Pepco Three Months Ended June 30, 2020 Total NDT Fund Mark-to-Market Total Generation Mark-to-Market Life Insurance Contracts Eliminated in Consolidation Balance as of March 31, 2020 $ 1,088 $ 498 $ 862 $ 1,360 $ (314) $ 42 $ — Total realized / unrealized gains (losses) Included in net income (166) (1) (166) (a) (167) — 1 — Included in regulatory assets/liabilities (4) — — — (4) (b) — — Change in collateral (42) — (42) (42) — — — Purchases, sales, and settlements Purchases 30 3 27 30 — — — Sales (2) — (2) (2) — — — Settlements (1) (1) — (1) — — — Transfers into Level 3 (9) — (9) (c) (9) — — — Transfers out of Level 3 (11) — (11) (c) (11) — — — Balance as of June 30, 2020 $ 883 $ 499 $ 659 $ 1,158 $ (318) $ 43 $ — The amount of total (losses) gains included in income attributed to the change in unrealized gains (losses) related to assets and liabilities as of June 30, 2020 $ (72) $ (1) $ (72) $ (73) $ — $ 1 $ — Exelon Generation ComEd PHI and Pepco Six Months Ended June 30, 2020 Total NDT Fund Mark-to-Market Total Generation Mark-to-Market Life Insurance Contracts Eliminated in Consolidation Balance as of December 31, 2019 $ 1,068 $ 511 $ 817 $ 1,328 $ (301) $ 41 $ — Total realized / unrealized gains (losses) Included in net income (156) (2) (156) (a) (158) — 2 — Included in noncurrent payables to affiliates — (1) — (1) — — 1 Included in regulatory assets (18) — — — (17) (b) — (1) Change in collateral (41) — (41) (41) — — — Purchases, sales, and settlements Purchases 71 6 65 71 — — — Sales (24) — (24) (24) — — — Settlements (15) (15) — (15) — — — Transfers into Level 3 (6) — (6) (c) (6) — — — Transfers out of Level 3 4 — 4 (c) 4 — — — Balance as of June 30, 2020 $ 883 $ 499 $ 659 $ 1,158 $ (318) $ 43 $ — The amount of total gains (losses) included in income attributed to the change in unrealized gains (losses) related to assets and liabilities as of June 30, 2020 $ 115 $ (2) $ 115 $ 113 $ — $ 2 $ — __________ (a) Includes an addition of $15 million for realized losses and a reduction of $114 million for realized gains due to the settlement of derivative contracts for the three and six months ended June 30, 2021. Includes a reduction of $94 million and $271 million for realized gains due to the settlement of derivative contracts for the three and six months ended June 30, 2020. (b) Includes $25 million of increases in fair value and an increase for realized losses due to settlements of $5 million recorded in purchased power expense associated with floating-to-fixed energy swap contracts with unaffiliated suppliers for the three months ended June 30, 2021. Includes $23 million of increases in fair value and an increase for realized losses due to settlements of $13 million recorded in purchased power expense associated with floating-to-fixed energy swap contracts with unaffiliated suppliers for the six months ended June 30, 2021. Includes $12 million of decreases in fair value and an increase for realized losses due to settlements of $8 million recorded in purchased power expense associated with floating-to-fixed energy swap contracts with unaffiliated suppliers for the three months ended June 30, 2020. Includes $35 million of decrease in fair value and an increase for realized losses due to settlements of $18 million recorded in purchased power expense associated with floating-to-fixed energy swap contracts with unaffiliated suppliers for the six months ended June 30, 2020. (c) Transfers into and out of Level 3 generally occur when the contract tenor becomes less and more observable respectively, primarily due to changes in market liquidity or assumptions for certain commodity contracts. The following tables present the income statement classification of the total realized and unrealized gains (losses) included in income for Level 3 assets and liabilities measured at fair value on a recurring basis during the three and six months ended June 30, 2021 and 2020: Exelon Generation PHI and Pepco Operating Purchased Operating and Maintenance Other, net Operating Purchased Other, net Operating and Maintenance Total (losses) gains included in net income for the three months ended June 30, 2021 $ (555) $ 196 $ 1 $ 1 $ (555) $ 196 $ 1 $ 1 Total (losses) gain included in net income for the six months ended June 30, 2021 (670) 34 2 2 (670) 34 2 2 Total unrealized (losses) gains for the three months ended June 30, 2021 (543) 169 1 1 (543) 169 1 1 Total unrealized (losses) gains for the six months ended June 30, 2021 (608) 86 2 2 (608) 86 2 2 Exelon Generation PHI and Pepco Operating Purchased Operating and Maintenance Other, net Operating Purchased Other, net Operating and Maintenance Total (losses) gains included in net income for the three months ended June 30, 2020 $ (137) $ (29) $ 1 $ — $ (137) $ (29) $ — $ 1 Total (losses) gains included in net income for the six months ended June 30, 2020 (65) (91) 2 — (65) (91) — 2 Total unrealized (losses) gains for the three months ended June 30, 2020 (39) (33) 1 (1) (39) (33) (1) 1 Total unrealized gains (losses) for the six months ended June 30, 2020 166 (51) 2 (2) 166 (51) (2) 2 Valuation Techniques Used to Determine Fair Value Exelon’s valuation techniques used to measure the fair value of the assets and liabilities shown in the tables below are in accordance with the policies discussed in Note 18 — Fair Value of Financial Assets and Liabilities of the Exelon 2020 Form 10-K. Valuation Techniques Used to Determine Net asset Value (Exelon and Generation) Certain NDT Fund Investments are not classified within the fair value hierarchy and are included under the heading “Not subject to leveling” in the table above. These investments are measured at fair value using NAV per share as a practical expedient and include commingled funds, mutual funds which are not publicly quoted, managed private credit funds, private equity and real estate funds. For commingled funds and mutual funds, which are not publicly quoted, the fair value is primarily derived from the quoted prices in active markets on the underlying securities and can typically be redeemed monthly with 30 or less days of notice and without further restrictions. For managed private credit funds, the fair value is determined using a combination of valuation models including cost models, market models, and income models and typically cannot be redeemed until maturity of the term loan. Private equity and real estate investments include those in limited partnerships that invest in operating companies and real estate holding companies that are not publicly traded on a stock exchange, such as, leveraged buyouts, growth capital, venture capital, distressed investments, investments in natural resources, and direct investments in pools of real estate properties. These investments typically cannot be redeemed and are generally liquidated over a period of 8 to 10 years from the initial investment date, which is based on Exelon’s understanding of the investment funds. Private equity and real estate valuations are reported by the fund manager and are based on the valuation of the underlying investments, which include inputs such as cost, operating results, discounted future cash flows, market based comparable data, and independent appraisals from sources with professional qualifications. These valuation inputs are unobservable. Mark-to-Market Derivatives (Exelon, Generation, and ComEd) The table below discloses the significant inputs to the forward curve used to value mark-to-market derivatives. Type of trade Fair Value at June 30, 2021 Fair Value at December 31, 2020 Valuation Unobservable 2021 Range & Arithmetic Average 2020 Range & Arithmetic Average Mark-to-market derivatives — Economic Hedges (Exelon and Generation) (a)(b) $ (285) $ 245 Discounted Forward power $7.13 - $281 $39 $2.25 - $163 $30 Forward gas $1.53 - $12.51 $3.10 $1.57 - $7.88 $2.59 Option Volatility 11% - 209% 33% 11% - 237% 32% Mark-to-market derivatives — Proprietary trading (Exelon and Generation) (a)(b) $ (4) $ 23 Discounted Forward power $10 - $132 $38 $10 - $106 $27 Mark-to-market derivatives (Exelon and ComEd) $ (265) $ (301) Discounted Forward heat (c) 9x - 10x 9.13x 8x - 9x 8.85x Marketability 3% - 7% 4.77% 3% - 8% 4.93% Renewable 94% - 122% 99% 91% - 123% 99% __________ (a) The valuation techniques, unobservable inputs, ranges and arithmetic averages are the same for the asset and liability positions. (b) The fair values do not include cash collateral (received)/posted on level three positions of $(176) million and $162 million as of June 30, 2021 and December 31, 2020, respectively. (c) Quoted forward natural gas rates are utilized to project the forward power curve for the delivery of energy at specified future dates. The natural gas curve is extrapolated beyond its observable period to the end of the contract’s delivery. The inputs listed above, which are as of the balance sheet date, would have a direct impact on the fair values of the above instruments if they were adjusted. The significant unobservable inputs used in the fair value measurement of Generation’s commodity derivatives are forward commodity prices and for options is price volatility. Increases (decreases) in the forward commodity price in isolation would result in significantly higher (lower) fair values for long positions (contracts that give Generation the obligation or option to purchase a commodity), with offsetting impacts to short positions (contracts that give Generation the obligation or right to sell a commodity). Increases (decreases) in volatility would increase (decrease) the value for the holder of the option (writer of the option). Generally, a change in the estimate of forward commodity prices is unrelated to a change in the estimate of volatility of prices. An increase to the reserves listed above would decrease the fair value of the positions. An increase to the heat rate or renewable factors would increase the fair value accordingly. Generally, interrelationships exist between market prices of natural gas and power. As such, an increase in natural gas pricing would potentially have a similar impact on forward power markets.

Commitments and Contingencies (

Commitments and Contingencies (All Registrants)	6 Months Ended
Commitments and Contingencies (All Registrants)	Jun. 30, 2021
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies (All Registrants)	Commitments and Contingencies (All Registrants) The following is an update to the current status of commitments and contingencies set forth in Note 19 of the Exelon 2020 Form 10-K. Commitments PHI Merger Commitments (Exelon, PHI, Pepco, DPL and ACE). Approval of the PHI Merger in Delaware, New Jersey, Maryland and the District of Columbia was conditioned upon Exelon and PHI agreeing to certain commitments. The following amounts represent total commitment costs that have been recorded since the acquisition date and the total remaining obligations for Exelon, PHI, Pepco, DPL, and ACE as of June 30, 2021: Description Exelon PHI Pepco DPL ACE Total commitments $ 513 $ 320 $ 120 $ 89 $ 111 Remaining commitments (a) 76 63 52 7 4 __________ (a) Remaining commitments extend through 2026 and include rate credits, energy efficiency programs and delivery system modernization. In addition, Exelon is committed to develop or to assist in the commercial development of approximately 37 MWs of new solar generation in Maryland, District of Columbia, and Delaware at an estimated cost of approximately $135 million, which will generate future earnings at Exelon and Generation. Investment costs, which are expected to be primarily capital in nature, are recognized as incurred and recorded in Exelon's and Generation's financial statements. As of June 30, 2021, approximately 33 MWs of new generation were developed and Exelon and Generation have incurred costs of $121 million. Exelon has also committed to purchase 100 MWs of wind energy in PJM. DPL has committed to conducting three RFPs to procure up to a total of 120 MWs of wind RECs for the purpose of meeting Delaware's renewable portfolio standards. DPL has conducted two of the three wind REC RFPs. The first 40 MW wind REC tranche was conducted in 2017 and did not result in a purchase agreement. The second 40 MW wind REC tranche was conducted in 2018 and resulted in a proposed REC purchase agreement that was approved by the DPSC in 2019. The third and final 40 MW wind REC tranche will be conducted in 2022. Commercial Commitments (All Registrants). The Registrants’ commercial commitments as of June 30, 2021, representing commitments potentially triggered by future events were as follow s: Expiration within Total 2021 2022 2023 2024 2025 2026 and beyond Exelon Letters of credit $ 1,751 $ 591 $ 1,160 $ — $ — $ — $ — Surety bonds (a) 920 619 299 — 2 — — Financing trust guarantees 378 — — — — — 378 Guaranteed lease residual values (b) 30 — 3 3 6 6 12 Total commercial commitments $ 3,079 $ 1,210 $ 1,462 $ 3 $ 8 $ 6 $ 390 Generation Letters of credit $ 1,735 $ 578 $ 1,157 $ — $ — $ — $ — Surety bonds (a) 772 514 258 — — — — Total commercial commitments $ 2,507 $ 1,092 $ 1,415 $ — $ — $ — $ — ComEd Letters of credit $ 7 $ 7 $ — $ — $ — $ — $ — Surety bonds (a) 17 9 6 — 2 — — Financing trust guarantees 200 — — — — — 200 Total commercial commitments $ 224 $ 16 $ 6 $ — $ 2 $ — $ 200 PECO Surety bonds (a) $ 3 $ 1 $ 2 $ — $ — $ — $ — Financing trust guarantees 178 — — — — — 178 Total commercial commitments $ 181 $ 1 $ 2 $ — $ — $ — $ 178 BGE Letters of credit $ 2 $ — $ 2 $ — $ — $ — $ — Surety bonds (a) 3 2 1 — — — — Total commercial commitments $ 5 $ 2 $ 3 $ — $ — $ — $ — PHI Surety bonds (a) $ 25 $ 8 $ 17 $ — $ — $ — $ — Guaranteed lease residual values (b) 30 — 3 3 6 6 12 Total commercial commitments $ 55 $ 8 $ 20 $ 3 $ 6 $ 6 $ 12 Pepco Surety bonds (a) $ 17 $ 4 $ 13 $ — $ — $ — $ — Guaranteed lease residual values (b) 10 — 1 1 2 2 4 Total commercial commitments $ 27 $ 4 $ 14 $ 1 $ 2 $ 2 $ 4 DPL Surety bonds (a) $ 4 $ 2 $ 2 $ — $ — $ — $ — Guaranteed lease residual values (b) 13 — 1 1 3 3 5 Total commercial commitments $ 17 $ 2 $ 3 $ 1 $ 3 $ 3 $ 5 ACE Surety bonds (a) $ 4 $ 2 $ 2 $ — $ — $ — $ — Guaranteed lease residual values (b) 7 — 1 1 1 1 3 Total commercial commitments $ 11 $ 2 $ 3 $ 1 $ 1 $ 1 $ 3 __________ (a) Surety bonds—Guarantees issued related to contract and commercial agreements, excluding bid bonds. (b) Represents the maximum potential obligation in the event that the fair value of certain leased equipment and fleet vehicles is zero at the end of the maximum lease term. The lease term associated with these assets ranges from 1 to 8 years. The maximum potential obligation at the end of the minimum lease term would be $75 million guaranteed by Exelon and PHI, of which $26 million, $31 million, and $18 million is guaranteed by Pepco, DPL, and ACE, respectively. Historically, payments under the guarantees have not been made and PHI believes the likelihood of payments being required under the guarantees is remote. Environmental Remediation Matters General (All Registrants). The Registrants’ operations have in the past, and may in the future, require substantial expenditures to comply with environmental laws. Additionally, under Federal and state environmental laws, the Registrants are generally liable for the costs of remediating environmental contamination of property now or formerly owned by them and of property contaminated by hazardous substances generated by them. The Registrants own or lease a number of real estate parcels, including parcels on which their operations or the operations of others may have resulted in contamination by substances that are considered hazardous under environmental laws. In addition, the Registrants are currently involved in a number of proceedings relating to sites where hazardous substances have been deposited and may be subject to additional proceedings in the future. Unless otherwise disclosed, the Registrants cannot reasonably estimate whether they will incur significant liabilities for additional investigation and remediation costs at these or additional sites identified by the Registrants, environmental agencies or others, or whether such costs will be recoverable from third parties, including customers. Additional costs could have a material, unfavorable impact on the Registrants' financial statements. MGP Sites (Exelon and the Utility Registrants). ComEd, PECO, BGE, and DPL have identified sites where former MGP or gas purification activities have or may have resulted in actual site contamination. For almost all of these sites, there are additional PRPs that may share responsibility for the ultimate remediation of each location. • ComEd has 21 sites that are currently under some degree of active study and/or remediation. ComEd expects the majority of the remediation at these sites to continue through at least 2026. • PECO has 7 sites that are currently under some degree of active study and/or remediation. PECO expects the majority of the remediation at these sites to continue through at least 2023. • BGE has 4 sites that currently require some level of remediation and/or ongoing activity. BGE expects the majority of the remediation at these sites to continue through at least 2023. • DPL has 1 site that is currently under study and the required cost at the site is not expected to be material. The historical nature of the MGP and gas purification sites and the fact that many of the sites have been buried and built over, impacts the ability to determine a precise estimate of the ultimate costs prior to initial sampling and determination of the exact scope and method of remedial activity. Management determines its best estimate of remediation costs using all available information at the time of each study, including probabilistic and deterministic modeling for ComEd and PECO, and the remediation standards currently required by the applicable state environmental agency. Prior to completion of any significant clean up, each site remediation plan is approved by the appropriate state environmental agency. ComEd, pursuant to an ICC order, and PECO, pursuant to settlements of natural gas distribution rate cases with the PAPUC, are currently recovering environmental remediation costs of former MGP facility sites through customer rates. While BGE and DPL do not have riders for MGP clean-up costs, they have historically received recovery of actual clean-up costs in distribution rates. As of June 30, 2021 and December 31, 2020, the Registrants had accrued the following undiscounted amounts for environmental liabilities in Other current liabilities and Other deferred credits and other liabilities within their respective Consolidated Balance Sheets: June 30, 2021 December 31, 2020 Total environmental Portion of total related to Total environmental Portion of total related to Exelon $ 461 $ 297 $ 483 $ 314 Generation 117 — 121 — ComEd 273 272 293 293 PECO 22 20 23 21 BGE 6 5 2 — PHI 43 — 44 — Pepco 41 — 42 — DPL 1 — 1 — ACE 1 — 1 — Cotter Corporation (Exelon and Generation). The EPA has advised Cotter Corporation (Cotter), a former ComEd subsidiary, that it is potentially liable in connection with radiological contamination at a site known as the West Lake Landfill in Missouri. In 2000, ComEd sold Cotter to an unaffiliated third-party. As part of the sale, ComEd agreed to indemnify Cotter for any liability arising in connection with the West Lake Landfill. In connection with Exelon’s 2001 corporate restructuring, this responsibility to indemnify Cotter was transferred to Generation. Including Cotter, there are three PRPs participating in the West Lake Landfill remediation proceeding. Investigation by Generation has identified a number of other parties who also may be PRPs and could be liable to contribute to the final remedy. Further investigation is ongoing. In September 2018, the EPA issued its Record of Decision Amendment (RODA) for the selection of a final remedy. The RODA modified the remedy previously selected by EPA in its 2008 Record of Decision (ROD). While the ROD required only that the radiological materials and other wastes at the site be capped, the 2018 RODA requires partial excavation of the radiological materials in addition to the previously selected capping remedy. The RODA also allows for variation in depths of excavation depending on radiological concentrations. The EPA and the PRPs have entered into a Consent Agreement to perform the Remedial Design, which is expected to be completed by early 2022. In March 2019 the PRPs received Special Notice Letters from the EPA to perform the Remedial Action work. On October 8, 2019, Cotter (Generation’s indemnitee) provided a non-binding good faith offer to conduct, or finance, a portion of the remedy, subject to certain conditions. The total estimated cost of the remedy, taking into account the current EPA technical requirements and the total costs expected to be incurred collectively by the PRPs in fully executing the remedy, is approximately $280 million, including cost escalation on an undiscounted basis, which would be allocated among the final group of PRPs. Generation has determined that a loss associated with the EPA’s partial excavation and enhanced landfill cover remedy is probable and has recorded a liability included in the table above, that reflects management’s best estimate of Cotter’s allocable share of the ultimate cost. Given the joint and several nature of this liability, the magnitude of Generation’s ultimate liability will depend on the actual costs incurred to implement the required remedy as well as on the nature and terms of any cost-sharing arrangements with the final group of PRPs. Therefore, it is reasonably possible that the ultimate cost and Cotter's associated allocable share could differ significantly once these uncertainties are resolved, which could have a material impact on Exelon's and Generation's future financial statements. One of the other PRPs has indicated it will be making a contribution claim against Cotter for costs that it has incurred to prevent a subsurface fire from spreading to those areas of the West Lake Landfill where radiological materials are believed to have been disposed. At this time, Exelon and Generation do not possess sufficient information to assess this claim and therefore are unable to estimate a range of loss, if any. As such, no liability has been recorded for the potential contribution claim. It is reasonably possible, however, that resolution of this matter could have a material, unfavorable impact on Exelon’s and Generation's financial statements. In January 2018, the PRPs were advised by the EPA that it will begin an additional investigation and evaluation of groundwater conditions at the West Lake Landfill. In September 2018, the PRPs agreed to an Administrative Settlement Agreement and Order on Consent for the performance by the PRPs of the groundwater Remedial Investigation and Feasibility Study (RI/FS). The purpose of this RI/FS is to define the nature and extent of any groundwater contamination from the West Lake Landfill site and evaluate remedial alternatives. Generation estimates the undiscounted cost for the groundwater RI/FS to be approximately $30 million. Generation determined a loss associated with the RI/FS is probable and has recorded a liability included in the table above that reflects management’s best estimate of Cotter’s allocable share of the cost among the PRPs. At this time Generation cannot predict the likelihood or the extent to which, if any, remediation activities may be required and therefore cannot estimate a reasonably possible range of loss for response costs beyond those associated with the RI/FS component. It is reasonably possible, however, that resolution of this matter could have a material, unfavorable impact on Exelon’s and Generation’s future financial statements. In August 2011, Cotter was notified by the DOJ that Cotter is considered a PRP with respect to the government’s clean-up costs for contamination attributable to low level radioactive residues at a former storage and reprocessing facility named Latty Avenue near St. Louis, Missouri. The Latty Avenue site is included in ComEd’s (now Generation's) indemnification responsibilities discussed above as part of the sale of Cotter. The radioactive residues had been generated initially in connection with the processing of uranium ores as part of the U.S. Government’s Manhattan Project. Cotter purchased the residues in 1969 for initial processing at the Latty Avenue facility for the subsequent extraction of uranium and metals. In 1976, the NRC found that the Latty Avenue site had radiation levels exceeding NRC criteria for decontamination of land areas. Latty Avenue was investigated and remediated by the United States Army Corps of Engineers pursuant to funding under FUSRAP. Pursuant to a series of annual agreements since 2011, the DOJ and the PRPs have tolled the statute of limitations until August 31, 2021 so that settlement discussions can proceed. On August 3, 2020, the DOJ advised Cotter and the other PRPs that it is seeking approximately $90 million from all the PRPs and has directed that the PRPs must submit a good faith joint proposed settlement offer. At this time, the DOJ has stayed their request for a good faith offer while the parties review cost documentation associated with the cost claim. Generation has determined that a loss associated with this matter is probable under its indemnification agreement with Cotter and has recorded an estimated liability, which is included in the table above. Benning Road Site (Exelon, Generation, PHI, and Pepco) . In September 2010, PHI received a letter from EPA identifying the Benning Road site as one of six land-based sites potentially contributing to contamination of the lower Anacostia River. A portion of the site was formerly the location of a Pepco Energy Services electric generating facility, which was deactivated in June 2012. The remaining portion of the site consists of a Pepco transmission and distribution service center that remains in operation. In December 2011, the U.S. District Court for the District of Columbia approved a Consent Decree entered into by Pepco and Pepco Energy Services with the DOEE, which requires Pepco and Pepco Energy Services to conduct a RI/FS for the Benning Road site and an approximately 10 to 15-acre portion of the adjacent Anacostia River. Since 2013, Pepco and Pepco Energy Services (now Generation, pursuant to Exelon's 2016 acquisition of PHI) have been performing RI work and have submitted multiple draft RI reports to the DOEE. In September 2019, Pepco and Generation issued a draft “final” RI report which DOEE approved on February 3, 2020. Pepco and Generation are developing a FS to evaluate possible remedial alternatives for submission to DOEE. The Court has established a schedule for completion of the FS, and approval by the DOEE, by March 16, 2022. After completion and approval of the FS, DOEE will prepare a Proposed Plan for public comment and then issue a ROD identifying any further response actions determined to be necessary. PHI, Pepco, and Generation have determined that a loss associated with this matter is probable and have accrued an estimated liability, which is included in the table above. Anacostia River Tidal Reach (Exelon, PHI, and Pepco) . Contemporaneous with the Benning Road site RI/FS being performed by Pepco and Generation, DOEE and NPS have been conducting a separate RI/FS focused on the entire tidal reach of the Anacostia River extending from just north of the Maryland-District of Columbia boundary line to the confluence of the Anacostia and Potomac Rivers. The river-wide RI incorporated the results of the river sampling performed by Pepco and Pepco Energy Services as part of the Benning RI/FS, as well as similar sampling efforts conducted by owners of other sites adjacent to this segment of the river and supplemental river sampling conducted by DOEE’s contractor. In April 2018, DOEE released a draft RI report for public review and comment. Pepco submitted written comments to the draft RI and participated in a public hearing. Pepco has determined that it is probable that costs for remediation will be incurred and recorded a liability in the third quarter 2019 for management’s best estimate of its share of those costs. On September 30, 2020, DOEE released its Interim ROD. The Interim ROD reflects an adaptive management approach which will require several identified “hot spots” in the river to be addressed first while continuing to conduct studies and to monitor the river to evaluate improvements and determine potential future remediation plans. The adaptive management process chosen by DOEE is less intrusive, provides more long-term environmental certainty, is less costly, and allows for site specific remediation plans already underway, including the plan for the Benning Road site to proceed to conclusion. Pepco concluded that incremental exposure remains reasonably possible, but management cannot reasonably estimate a range of loss beyond the amounts recorded, which are included in the table above. On July 12, 2021, DOEE and NPS held a virtual meeting with the PRP's in response to a General Notice Letter sent by each agency inviting the PRP's to participate in discussions, which PEPCO attended. In addition to the activities associated with the remedial process outlined above, CERCLA separately requires federal and state (here including Washington, D.C.) Natural Resource Trustees (federal or state agencies designated by the President or the relevant state, respectively, or Indian tribes) to conduct an assessment of any damages to natural resources within their jurisdiction as a result of the contamination that is being remediated. The Trustees can seek compensation from responsible parties for such damages, including restoration costs. During the second quarter of 2018, Pepco became aware that the Trustees are in the beginning stages of a Natural Resources Damages (NRD) assessment, a process that often takes many years beyond the remedial decision to complete. Pepco has concluded that a loss associated with the eventual NRD assessment is reasonably possible. Due to the very early stage of the assessment process, Pepco cannot reasonably estimate the range of loss. Litigation and Regulatory Matters Asbestos Personal Injury Claims (Exelon and Generation). Generation maintains a reserve for claims associated with asbestos-related personal injury actions in certain facilities that are currently owned by Generation or were previously owned by ComEd and PECO. The estimated liabilities are recorded on an undiscounted basis and exclude the estimated legal costs associated with handling these matters, which could be material. At June 30, 2021 and December 31, 2020, Exelon and Generation had recorded estimated liabilities of approximately $85 million and $89 million, respectively, in total for asbestos-related bodily injury claims. As of June 30, 2021, approximately $21 million of this amount related to 230 open claims presented to Generation, while the remaining $64 million is for estimated future asbestos-related bodily injury claims anticipated to arise through 2055, based on actuarial assumptions and analyses, which are updated on an annual basis. On a quarterly basis, Generation monitors actual experience against the number of forecasted claims to be received and expected claim payments and evaluates whether adjustments to the estimated liabilities are necessary. It is reasonably possible that additional exposure to estimated future asbestos-related bodily injury claims in excess of the amount accrued could have a material, unfavorable impact on Exelon’s and Generation’s financial statements. However, management cannot reasonably estimate a range of loss beyond the amounts recorded. Deferred Prosecution Agreement (DPA) and Related Matters (Exelon and ComEd). Exelon and ComEd received a grand jury subpoena in the second quarter of 2019 from the U.S. Attorney’s Office for the Northern District of Illinois (USAO) requiring production of information concerning their lobbying activities in the State of Illinois. On October 4, 2019, Exelon and ComEd received a second grand jury subpoena from the USAO requiring production of records of any communications with certain individuals and entities. On October 22, 2019, the SEC notified Exelon and ComEd that it had also opened an investigation into their lobbying activities. On July 17, 2020, ComEd entered into a DPA with the USAO to resolve the USAO investigation. Under the DPA, the USAO filed a single charge alleging that ComEd improperly gave and offered to give jobs, vendor subcontracts, and payments associated with those jobs and subcontracts for the benefit of the Speaker of the Illinois House of Representatives and the Speaker’s associates, with the intent to influence the Speaker’s action regarding legislation affecting ComEd’s interests. The DPA provides that the USAO will defer any prosecution of such charge and any other criminal or civil case against ComEd in connection with the matters identified therein for a three-year period subject to certain obligations of ComEd, including payment to the U.S. Treasury of $200 million, which was paid in November 2020. Exelon was not made a party to the DPA, and therefore the investigation by the USAO into Exelon’s activities ended with no charges being brought against Exelon. The SEC’s investigation remains ongoing and Exelon and ComEd have cooperated fully and intend to continue to cooperate fully with the SEC. Exelon and ComEd cannot predict the outcome of the SEC investigation. No loss contingency has been reflected in Exelon's and ComEd's consolidated financial statements with respect to the SEC investigation, as this contingency is neither probable nor reasonably estimable at this time. Subsequent to Exelon announcing the receipt of the subpoenas, various lawsuits were filed, and various demand letters were received related to the subject of the subpoenas, the conduct described in the DPA and the SEC's investigation, including: • A putative class action lawsuit against Exelon and certain officers of Exelon and ComEd was filed in federal court in December 2019 alleging misrepresentations and omissions in Exelon’s SEC filings related to ComEd’s lobbying activities and the related investigations. The complaint was amended on September 16, 2020, to dismiss two of the original defendants and add other defendants, including ComEd. Defendants filed a motion to dismiss in November 2020. The court denied the motion in April 2021. On May 26, 2021, defendants moved the court to certify its order denying the motion to dismiss for interlocutory appeal. Briefing on the motion was completed in June 2021 and the motion remains pending. While that motion remains pending, the litigation has proceeded and in May 2021, the parties each filed respective initial discovery disclosures. On June 9, 2021, defendants filed their answer and affirmative defenses to the complaint. The parties are currently engaged in discovery. • Three putative class action lawsuits against ComEd and Exelon were filed in Illinois state court in the third quarter of 2020 seeking restitution and compensatory damages on behalf of ComEd customers. The cases were consolidated into a single action in October of 2020. In November 2020, the Citizens Utility Board (CUB) filed a motion to intervene in the cases pursuant to an Illinois statute allowing CUB to intervene as a party or otherwise participate on behalf of utility consumers in any proceeding which affects the interest of utility consumers. On November 23, 2020, the court allowed CUB’s intervention, but denied CUB’s request to stay these cases. Plaintiffs subsequently filed a consolidated complaint, and ComEd and Exelon filed a motion to dismiss on jurisdictional and substantive grounds on January 11, 2021. Briefing on that motion was completed on March 2, 2021. The parties agreed, on March 25, 2021, along with the federal court plaintiffs, to jointly engage in mediation. The parties participated in a one-day mediation on June 7, 2021 but no settlement was reached. Oral argument on the state court motion to dismiss was held on August 4, 2021. No ruling has yet been issued. • Four putative class action lawsuits against ComEd and Exelon were filed in federal court in the third quarter of 2020 alleging, among other things, civil violations of federal racketeering laws. In addition, CUB filed a motion to intervene in these cases on October 22, 2020 which was granted on December 23, 2020. In addition, on December 2, 2020, the court appointed interim lead plaintiffs in the federal cases which consisted of counsel for three of the four federal cases. These plaintiffs filed a consolidated complaint on January 5, 2021. CUB also filed its own complaint against ComEd only on the same day. The remaining federal case, Potter, et al. v. Exelon et al, differed from the other lawsuits as it named additional individual defendants not named in the consolidated complaint. The Potter plaintiffs decided not to move forward with their separate lawsuit at this time and voluntarily dismissed their complaint without prejudice on April 5, 2021. ComEd and Exelon moved to dismiss the consolidated class action complaint and CUB’s complaint on February 4, 2021. Briefing on that motion was completed on March 22, 2021. As noted above, on March 25, 2021, the parties agreed, along with the state court plaintiffs, to jointly engage in mediation. The parties participated in a one-day mediation on June 7, 2021 but no settlement was reached. On June 14, 2021, plaintiffs filed a motion for leave to file a sur-reply to defendants' motion to dismiss, to which ComEd and Exelon objected. The court has taken the motion for leave under advisement. • Five shareholders sent letters to the Exelon Board of Directors between 2020 and 2021 demanding, among other things, that the Exelon Board of Directors investigate and address alleged breaches of fiduciary duties and other alleged violations by Exelon and ComEd officers and directors related to the conduct described in the DPA. In the first quarter of 2021, the Exelon Board of Directors appointed a Special Litigation Committee (“SLC”) consisting of disinterested and independent parties to investigate and address these shareholders’ allegations and make recommendations to the Exelon Board of Directors based on the outcome of the SLC’s investigation. In July, one of the demand letter shareholders filed a derivative action against current and former Exelon and ComEd officers and directors, and against Exelon, as nominal defendant, asserting the same claims made in its demand letter. No loss contingencies have been reflec ted in Exelon’s and ComEd’s consolidated financial statements with respect to these matters, as such contingencies are neither probable nor reasonably estimable at this time. Impacts of the February 2021 Extreme Cold Weather Event and Texas-based Generating Assets Outages (Exelon and Generation). Beginning on February 15, 2021, Generation’s Texas-based generating assets within the ERCOT market, specifically Colorado Bend II, Wolf Hollow II, and Handley, experienced outages as a result of extreme cold weather conditions. In addition, those weather conditions drove increased demand for service, dramatically increased wholesale power prices, and also increased gas prices in certain regions. See Note 3 — Regulatory Matters for additional information. Various lawsuits have been filed against Generation since March 2021 related to these events, including: • On March 5, 2021, Generation, along with more than 160 power generators and transmission and distribution companies, was sued by approximately 160 individually named plaintiffs, purportedly on behalf of all Texans who allegedly suffered loss of life or sustained personal injury, property damage or other losses as a result of the weather events. The plaintiffs allege that the defendants failed to properly prepare for the cold weather and failed to properly conduct their operations, seeking compensatory as well as punitive damages. On April 26, 2021, another multi-plaintiff lawsuit was filed on behalf of approximately 90 plaintiffs against more than 300 defendants, including Generation, involving similar allegations of liability and claims of personal injury and property damage. Since March 2021, approximately 60 additional lawsuits, naming multiple defendants including Generation, were filed by individual or multiple plaintiffs in different Texas counties, all arising out of the February weather events. These additional lawsuits allege wrongful death, property damage, or other losses. Co-defendants in these lawsuits include ERCOT, transmission and distribution utilities and other generators. Generation disputes liability and denies that it is responsible for any of plaintiffs’ alleged claims and is vigorously contesting them. No loss contingencies have been reflected in Exelon’s and Generation’s consolidated financial statements with respect to these matters, as such contingencies are neither probable nor reasonably estimable at this time. • On March 22, 2021, a LDC filed a lawsuit in Missouri federal court against Generation for breach of contract and unjust enrichment, seeking damages of approximately $40 million. The plaintiff claims that Generation failed to deliver gas to its customers in February of 2021, causing the plaintiff to incur damages by forcing it to purchase gas for Generation’s customers and by Generation’s refusal to pay the resulting penalties. On March 26, 2021, Generation filed a complaint with the MPSC against the LDC to void the OFO penalties, or alternatively to grant a waiver or variance from the tariff requirements, to prohibit the LDC from billing or otherwise attempting to collect from Generation or any Missouri customer any portion of the penalties claimed by the LDC until the resolution of the complaint, and to prohibit the LDC from taking any retaliatory measure, including termination of service. The MPSC has scheduled an evidentiary hearing for January 2022. Based on the penalty provisions within the tariff that was in effect at the relevant time, Exelon and Generation have recorded a liability of approximately $40 million as of June 30, 2021. General (All Registrants). The Registrants are involved in various other litigation matters that are being defended and handled in the ordinary course of business. The assessment of whether a loss is probable or reasonably possible, and whether the loss or a range of loss is estimable, often involves a series of complex judgments about future events. The Registrants maintain accruals for such losses that are probable of being incurred and subject to reasonable estimation. Management is sometimes unable to estimate an amount or range of reasonably possible loss, particularly where (1) the damages sought are indeterminate, (2) the pro

Changes in Accumulated Other Co

Changes in Accumulated Other Comprehensive Income (Exelon)	6 Months Ended
Changes in Accumulated Other Comprehensive Income (Exelon)	Jun. 30, 2021
Changes in Accumulated Other Comprehensive Income [Abstract]
Changes in Accumulated Other Comprehensive Income [Text Block]	Changes in Accumulated Other Comprehensive Income (Exelon) The following tables present changes in Exelon's AOCI, net of tax, by component: Three Months Ended June 30, 2021 Losses on Cash Flow Hedges Pension and Non-Pension Postretirement Benefit Plan Items (a) Foreign Total Beginning balance $ (5) $ (3,319) $ (22) $ (3,346) OCI before reclassifications — — 2 2 Amounts reclassified from AOCI — 55 — 55 Net current-period OCI — 55 2 57 Ending balance $ (5) $ (3,264) $ (20) $ (3,289) Three Months Ended June 30, 2020 Losses on Cash Flow Hedges Pension and Non-Pension Postretirement Benefit Plan Items (a) Foreign Total Beginning balance $ (3) $ (3,135) $ (35) $ (3,173) OCI before reclassifications — 2 2 4 Amounts reclassified from AOCI — 37 — 37 Net current-period OCI — 39 2 41 Ending balance $ (3) $ (3,096) $ (33) $ (3,132) Six Months Ended June 30, 2021 Losses on Cash Flow Hedges Pension and Non-Pension Postretirement Benefit Plan Items (a) Foreign Total Beginning balance $ (5) $ (3,372) $ (23) $ (3,400) OCI before reclassifications — (2) 3 1 Amounts reclassified from AOCI — 110 — 110 Net current-period OCI — 108 3 111 Ending balance $ (5) $ (3,264) $ (20) $ (3,289) Six Months Ended June 30, 2020 Losses on Cash Flow Hedges Pension and Non-Pension Postretirement Benefit Plan Items (a) Foreign Total Beginning balance $ (2) $ (3,165) $ (27) $ (3,194) OCI before reclassifications (1) (5) (6) (12) Amounts reclassified from AOCI — 74 — 74 Net current-period OCI (1) 69 (6) 62 Ending balance $ (3) $ (3,096) $ (33) $ (3,132) ______ (a) AOCI amounts are included in the computation of net periodic pension and OPEB cost. See Note 11 — Retirement Benefits for additional information. See Exelon's Statements of Operations and Comprehensive Income for individual components of AOCI. The following table presents income tax benefit (expense) allocated to each component of Exelon's other comprehensive income (loss): Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 Pension and non-pension postretirement benefit plans: Prior service benefit reclassified to periodic benefit cost $ 1 $ 4 $ 2 $ 8 Actuarial loss reclassified to periodic benefit cost (19) (17) (38) (34) Pension and non-pension postretirement benefit plans valuation adjustment (1) — (1) 3

Variable Interest Entities (Exe

Variable Interest Entities (Exelon, Generation, PHI and ACE)	6 Months Ended
	Jun. 30, 2021
Variable Interest Entity [Abstract]
Variable Interest Entity Disclosure	Variable Interest Entities (Exelon, Generation, PHI and ACE) At June 30, 2021 and December 31, 2020, Exelon, Generation, PHI, and ACE collectively consolidated several VIEs or VIE groups for which the applicable Registrant was the primary beneficiary (see Consolidated VIEs below) and had significant interests in several other VIEs for which the applicable Registrant does not have the power to direct the entities’ activities and, accordingly, was not the primary beneficiary (see Unconsolidated VIEs below). Consolidated and unconsolidated VIEs are aggregated to the extent that the entities have similar risk profiles. Consolidated VIEs The table below shows the carrying amounts and classification of the consolidated VIEs’ assets and liabilities included in the consolidated financial statements of Exelon, Generation, PHI, and ACE as of June 30, 2021 and December 31, 2020. The assets, except as noted in the footnotes to the table below, can only be used to settle obligations of the VIEs. The liabilities, except as noted in the footnote to the table below, are such that creditors, or beneficiaries, do not have recourse to the general credit of Exelon, Generation, PHI, and ACE. June 30, 2021 December 31, 2020 Exelon Generation PHI (a) ACE Exelon Generation PHI (a) ACE Cash and cash equivalents $ 233 $ 233 $ — $ — $ 98 $ 98 $ — $ — Restricted cash and cash equivalents 57 54 3 3 47 44 3 3 Accounts receivable Customer 169 169 — — 148 148 — — Other 44 44 — — 36 36 — — Unamortized energy contract assets 22 22 — — 22 22 — — Inventories, net Materials and supplies 255 255 — — 244 244 — — Assets held for sale (b) — — — — 101 101 — — Other current assets 408 404 4 — 674 669 5 — Total current assets 1,188 1,181 7 3 1,370 1,362 8 3 Property, plant, and equipment, net 5,656 5,656 — — 5,803 5,803 — — Nuclear decommissioning trust funds 3,215 3,215 — — 3,007 3,007 — — Unamortized energy contract assets 237 237 — — 249 249 — — Other noncurrent assets 35 26 9 9 52 42 10 10 Total noncurrent assets 9,143 9,134 9 9 9,111 9,101 10 10 Total assets (c) $ 10,331 $ 10,315 $ 16 $ 12 $ 10,481 $ 10,463 $ 18 $ 13 Long-term debt due within one year $ 84 $ 69 $ 15 $ 11 $ 94 $ 68 $ 26 $ 21 Accounts payable 67 67 — — 81 81 — — Accrued expenses 56 56 — — 70 70 — — Unamortized energy contract liabilities 1 1 — — 4 4 — — Liabilities held for sale (b) — — — — 16 16 — — Other current liabilities 1 1 — — 5 5 — — Total current liabilities 209 194 15 11 270 244 26 21 Long-term debt 860 860 — — 889 889 — — Asset retirement obligations 2,377 2,377 — — 2,318 2,318 — — Other noncurrent liabilities 133 133 — — 129 129 — — Total noncurrent liabilities 3,370 3,370 — — 3,336 3,336 — — Total liabilities (d) $ 3,579 $ 3,564 $ 15 $ 11 $ 3,606 $ 3,580 $ 26 $ 21 _________ (a) Includes certain purchase accounting adjustments from the PHI merger not pushed down to ACE. (b) In the fourth quarter of 2020, Generation entered into an agreement for the sale of a significant portion of Generation's solar business, and as a result of this transaction, Exelon and Generation reclassified the consolidated VIEs' solar assets and liabilities as held for sale. Completion of the transaction occurred in the first quarter of 2021. Refer to Note 2 - Mergers, Acquisitions, and Dispositions for additional information on the solar business. (c) Exelon’s and Generation’s balances include unrestricted assets for current unamortized energy contract assets of $22 million and $22 million, non-current unamortized energy contract assets of $216 million and $249 million, assets held for sale of $0 million and $9 million, and other unrestricted assets of $0 million and $1 million as of June 30, 2021 and December 31, 2020, respectively (d) Exelon’s and Generation’s balances include liabilities with recourse of $1 million and $8 million as of June 30, 2021 and December 31, 2020, respectively. As of June 30, 2021 and December 31, 2020, Exelon's and Generation's consolidated VIEs consist of: Consolidated VIE or VIE groups: Reason entity is a VIE: Reason Generation is primary beneficiary: CENG - A joint venture between Generation and EDF. Generation has a 50.01% equity ownership in CENG. See additional discussion below. Disproportionate relationship between equity interest and operational control as a result of the NOSA described further below. Generation conducts the operational activities. EGRP - A collection of wind and solar project entities. Generation has a 51% equity ownership in EGRP. See additional discussion below. Similar structure to a limited partnership and the limited partners do not have kick out rights with respect to the general partner. Generation conducts the operational activities. Bluestem Wind Energy Holdings, LLC - A Tax Equity structure which is consolidated by EGRP. Generation has a noncontrolling interest. Similar structure to a limited partnership and the limited partners do not have kick out rights with respect to the general partner. Generation conducts the operational activities. Antelope Valley - A solar generating facility, which is 100% owned by Generation. Antelope Valley sells all of its output to PG&E through a PPA. The PPA contract absorbs variability through a performance guarantee. Generation conducts all activities. Equity investment in distributed energy company - Generation has a 31% equity ownership. This distributed energy company has an interest in an unconsolidated VIE. (See Unconsolidated VIEs disclosure below). Generation fully impaired this investment in 2019. Similar structure to a limited partnership and the limited partners do not have kick out rights with respect to the general partner. Generation conducts the operational activities. NER - A bankruptcy remote, special purpose entity which is 100% owned by Generation, which purchases certain of Generation’s customer accounts receivable arising from the sale of retail electricity. NER’s assets will be available first and foremost to satisfy the claims of the creditors of NER. See Note 6 - Accounts Receivable for additional information on the sale of receivables. Equity capitalization is insufficient to support its operations. Generation conducts all activities. CENG - On April 1, 2014, Generation, CENG, and subsidiaries of CENG executed the NOSA pursuant to which Generation conducts all activities associated with the operations of the CENG fleet and provides corporate and administrative services to CENG and the CENG fleet for the remaining life of the CENG nuclear plants as if they were a part of the Generation nuclear fleet, subject to the CENG member rights of EDF. EDF has the option to sell its 49.99% equity interest in CENG to Generation. On November 20, 2019, Generation received notice of EDF's intention to exercise the put option to sell its interest in CENG to Generation and the put automatically exercised on January 19, 2020. Refer to Note 2 - Mergers, Acquisitions, and Dispositions for additional information. Exelon and Generation, where indicated, provide the following support to CENG: • Generation executed an Indemnity Agreement pursuant to which Generation agreed to indemnify EDF against third-party claims that may arise from any future nuclear incident (as defined in the Price-Anderson Act) in connection with the CENG nuclear plants or their operations. Exelon guarantees Generation’s obligations under this Indemnity Agreement. See Note 19 — Commitments and Contingencies of the Exelon 2020 Form 10-K for more details, • Generation and EDF share in the $688 million of contingent payment obligations for the payment of contingent retrospective premium adjustments for the nuclear liability insurance, and • Exelon has executed an agreement to provide up to $245 million to support the operations of CENG as well as a $165 million guarantee of CENG’s cash pooling agreement with its subsidiaries. EGRP - EGRP is a collection of wind and solar project entities and some of these project entities are VIEs that are consolidated by EGRP. Generation owns a number of limited liability companies that build, own, and operate solar and wind power facilities some of which are owned by EGRP. While Generation or EGRP owns 100% of the solar entities and 100% of the majority of the wind entities, it has been determined that certain of the solar and wind entities are VIEs because the entities require additional subordinated financial support in the form of a parental guarantee of debt, loans from the customers in order to obtain the necessary funds for construction of the solar facilities, or the customers absorb price variability from the entities through the fixed price power and/or REC purchase agreements. Generation is the primary beneficiary of these solar and wind entities that qualify as VIEs because Generation controls the design, construction, and operation of the facilities. There is limited recourse to Generation related to certain solar and wind entities. In 2017, Generation’s interests in EGRP were contributed to and are pledged for the ExGen Renewables IV non-recourse debt project financing structure. Refer to Note 17 — Debt and Credit Agreements of the Exelon 2020 Form 10-K for additional information on ExGen Renewables IV. As of June 30, 2021 and December 31, 2020, Exelon's, PHI's and ACE's consolidated VIE consists of: Consolidated VIEs: Reason entity is a VIE: Reason ACE is the primary beneficiary: ACE Funding - A special purpose entity formed by ACE for the purpose of securitizing authorized portions of ACE’s recoverable stranded costs through the issuance and sale of Transition Bonds. Proceeds from the sale of each series of Transition Bonds by ATF were transferred to ACE in exchange for the transfer by ACE to ATF of the right to collect a non-bypassable Transition Bond Charge from ACE customers pursuant to bondable stranded costs rate orders issued by the NJBPU in an amount sufficient to fund the principal and interest payments on Transition Bonds and related taxes, expenses and fees. ACE’s equity investment is a variable interest as, by design, it absorbs any initial variability of ATF. The bondholders also have a variable interest for the investment made to purchase the Transition Bonds. ACE controls the servicing activities. Unconsolidated VIEs Exelon’s and Generation’s variable interests in unconsolidated VIEs generally include equity investments and energy purchase and sale contracts. For the equity investments, the carrying amount of the investments is reflected in Exelon’s and Generation’s Consolidated Balance Sheets in Investments. For the energy purchase and sale contracts (commercial agreements), the carrying amount of assets and liabilities in Exelon’s and Generation’s Consolidated Balance Sheets that relate to their involvement with the VIEs are predominately related to working capital accounts and generally represent the amounts owed by, or owed to, Exelon and Generation for the deliveries associated with the current billing cycles under the commercial agreements. As of June 30, 2021 and December 31, 2020, Exelon and Generation had significant unconsolidated variable interests in several VIEs for which Exelon or Generation, as applicable, was not the primary beneficiary. These interests include certain equity method investments and certain commercial agreements. The following table presents summary information about Exelon's and Generation’s significant unconsolidated VIE entities: June 30, 2021 December 31, 2020 Commercial Equity Total Commercial Equity Total Total assets (a) $ 786 $ 378 $ 1,164 $ 777 $ 401 $ 1,178 Total liabilities (a) 95 210 305 61 223 284 Exelon's ownership interest in VIE (a) — 149 149 — 157 157 Other ownership interests in VIE (a) 691 19 710 716 21 737 _________ (a) These items represent amounts on the unconsolidated VIE balance sheets, not in Exelon’s or Generation’s Consolidated Balance Sheets. These items are included to provide information regarding the relative size of the unconsolidated VIEs. Exelon and Generation do not have any exposure to loss as they do not have a carrying amount in the equity investment VIEs as of June 30, 2021 and December 31, 2020. As of June 30, 2021 and December 31, 2020, Exelon's and Generation's unconsolidated VIEs consist of: Unconsolidated VIE groups: Reason entity is a VIE: Reason Generation is not the primary beneficiary: Equity investments in distributed energy companies - 1) Generation has a 90% equity ownership in a distributed energy company. 2) Generation, via a consolidated VIE, has a 90% equity ownership in another distributed energy company (See Consolidated VIEs disclosure above). Generation fully impaired this investment in 2019. Similar structures to a limited partnership and the limited partners do not have kick out rights with respect to the general partner. Generation does not conduct the operational activities. Energy Purchase and Sale agreements - Generation has several energy purchase and sale agreements with generating facilities. PPA contracts that absorb variability through fixed pricing. Generation does not conduct the operational activities.

Supplemental Financial Informat

Supplemental Financial Information (All Registrants)	6 Months Ended
Supplemental Financial Information (All Registrants)	Jun. 30, 2021
Supplemental Financial Information [Abstract]
Supplemental Financial Information (All Registrants)	Supplemental Financial Information (All Registrants) Supplemental Statement of Operations Information The following tables provide additional information about material items recorded in the Registrants' Consolidated Statements of Operations and Comprehensive Income. Operating revenues Exelon Generation PHI DPL Three Months Ended June 30, 2021 Operating lease income $ 13 $ 12 $ 1 $ 1 Variable lease income 74 74 — — Three Months Ended June 30, 2020 Operating lease income $ 14 $ 12 $ 1 $ 1 Variable lease income 80 79 1 1 Six Months Ended June 30, 2021 Operating lease income $ 17 $ 15 $ 2 $ 2 Variable lease income 137 137 — — Six Months Ended June 30, 2020 Operating lease income $ 18 $ 15 $ 2 $ 2 Variable lease income 149 148 1 1 Taxes other than income taxes Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE Three Months Ended June 30, 2021 Utility taxes (a) $ 206 $ 22 $ 61 $ 32 $ 20 $ 71 $ 65 $ 5 $ — Property 153 66 8 4 43 31 20 10 1 Payroll 61 30 6 4 5 7 1 1 1 Three Months Ended June 30, 2020 Utility taxes (a) $ 196 $ 23 $ 55 $ 31 $ 18 $ 69 $ 64 $ 5 $ — Property 149 64 8 4 40 33 21 11 1 Payroll 61 28 7 4 4 7 2 1 1 Six Months Ended June 30, 2021 Utility taxes (a) $ 423 $ 46 $ 121 $ 66 $ 45 $ 145 $ 132 $ 11 $ 1 Property 307 133 16 9 85 63 42 19 1 Payroll 122 58 13 8 9 14 3 3 2 Six Months Ended June 30, 2020 Utility taxes (a) $ 414 $ 49 $ 114 $ 62 $ 44 $ 145 $ 133 $ 10 $ 1 Property 297 133 15 8 79 62 41 20 1 Payroll 125 60 14 8 9 15 4 2 2 __________ (a) Generation’s utility tax represents gross receipts tax related to its retail operations, and the Utility Registrants' utility taxes represents municipal and state utility taxes and gross receipts taxes related to their operating revenues. The offsetting collection of utility taxes from customers is recorded in revenues in the Registrants’ Consolidated Statements of Operations and Comprehensive Income. Other, Net Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE Three Months Ended June 30, 2021 Decommissioning-related activities: Net realized income on NDT funds (a) Regulatory Agreement Units $ 144 $ 144 $ — $ — $ — $ — $ — $ — $ — Non-Regulatory Agreement Units 87 87 — — — — — — — Net unrealized gains on NDT funds Regulatory Agreement Units 361 361 — — — — — — — Non-Regulatory Agreement Units 193 193 — — — — — — — Regulatory offset to NDT fund-related activities (b) (402) (402) — — — — — — — Decommissioning-related activities 383 383 — — — — — — — AFUDC — Equity 35 — 9 6 7 12 10 1 1 Non-service net periodic benefit cost 26 — — — — — — — — Net unrealized gains from equity investments (c) 119 119 — — — — — — — Three Months Ended June 30, 2020 Decommissioning-related activities: Net realized income on NDT funds (a) Regulatory Agreement Units $ 30 $ 30 $ — $ — $ — $ — $ — $ — $ — Non-Regulatory Agreement Units 23 23 — — — — — — — Net unrealized gains on NDT funds Regulatory Agreement Units 645 645 — — — — — — — Non-Regulatory Agreement Units 452 452 — — — — — — — Regulatory offset to NDT fund-related activities (b) (542) (542) — — — — — — — Decommissioning-related activities 608 608 — — — — — — — AFUDC — Equity 26 — 8 4 6 8 6 1 1 Non-service net periodic benefit cost 14 — — — — — — — — Other, net Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE Six Months Ended June 30, 2021 Decommissioning-related activities: Net realized income on NDT funds (a) Regulatory Agreement Units $ 435 $ 435 $ — $ — $ — $ — $ — $ — $ — Non-Regulatory Agreement Units 290 290 — — — — — — — Net unrealized gains on NDT funds Regulatory Agreement Units 279 279 — — — — — — — Non-Regulatory Agreement Units 126 126 — — — — — — — Regulatory offset to NDT fund-related activities (b) (569) (569) — — — — — — — Decommissioning-related activities 561 561 — — — — — — — AFUDC — Equity 64 — 13 12 14 25 20 3 2 Non-service net periodic benefit cost 46 — — — — — — — — Net unrealized gains from equity investments (c) 96 96 — — — — — — — Six Months Ended June 30, 2020 Decommissioning-related activities: Net realized income on NDT funds (a) Regulatory Agreement Units $ 77 $ 77 $ — $ — $ — $ — $ — $ — $ — Non-Regulatory Agreement Units 104 104 — — — — — — — Net unrealized gains on NDT funds Regulatory Agreement Units (287) (287) — — — — — — — Non-Regulatory Agreement Units (253) (253) — — — — — — — Regulatory offset to NDT fund-related activities (b) 167 167 — — — — — — — Decommissioning-related activities (192) (192) — — — — — — — AFUDC — Equity 49 — 14 7 10 17 13 2 2 Non-service net periodic benefit cost 24 — — — — — — — — __________ (a) Realized income includes interest, dividends and realized gains and losses on sales of NDT fund investments. (b) Includes the elimination of decommissioning-related activities for the Regulatory Agreement Units except for decommissioning-related impacts that were not offset for the Byron units in the second quarter of 2021, including the elimination of income taxes related to all NDT fund activity for those units. See Note 10 — Asset Retirement Obligations of the Exelon 2020 Form 10-K for additional information regarding the accounting for nuclear decommissioning and Note 8 — Nuclear Decommissioning for additional information on the contractual offset suspension for the Byron units. (c) Net unrealized gains from equity investments that became publicly traded entities in the fourth quarter of 2020 and the first half of 2021. Supplemental Cash Flow Information The following tables provide additional information about material items recorded in the Registrants' Consolidated Statements of Cash Flows. Depreciation, amortization and accretion Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE Six Months Ended June 30, 2021 Property, plant, and equipment (a) $ 3,043 $ 1,844 $ 480 $ 165 $ 215 $ 309 $ 135 $ 84 $ 76 Amortization of regulatory assets (a) 291 — 109 8 78 95 64 20 11 Amortization of intangible assets, net (a) 29 25 — — — — — — — Amortization of energy contract assets and liabilities (b) 13 13 — — — — — — — Nuclear fuel (c) 549 549 — — — — — — — ARO accretion (d) 255 255 — — — — — — — Total depreciation, amortization and accretion $ 4,180 $ 2,686 $ 589 $ 173 $ 293 $ 404 $ 199 $ 104 $ 87 Six Months Ended June 30, 2020 Property, plant, and equipment (a) $ 1,715 $ 577 $ 458 $ 159 $ 195 $ 289 $ 126 $ 76 $ 69 Amortization of regulatory assets (a) 277 — 89 14 77 96 60 18 17 Amortization of intangible assets, net (a) 31 27 — — — — — — — Amortization of energy contract assets and liabilities (b) 12 10 — — — — — — — Nuclear fuel (c) 459 459 — — — — — — — ARO accretion (d) 247 247 — — — — — — — Total depreciation, amortization and accretion $ 2,741 $ 1,320 $ 547 $ 173 $ 272 $ 385 $ 186 $ 94 $ 86 __________ (a) Included in Depreciation and amortization in the Registrants' Consolidated Statements of Operations and Comprehensive Income. (b) Included in Operating revenues or Purchased power and fuel expense in the Registrants’ Consolidated Statements of Operations and Comprehensive Income. (c) Included in Purchased power and fuel expense in the Registrants’ Consolidated Statements of Operations and Comprehensive Income. (d) Included in Operating and maintenance expense in the Registrants’ Consolidated Statements of Operations and Comprehensive Income. Other non-cash operating activities Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE Six Months Ended June 30, 2021 Pension and non-pension postretirement benefit costs $ 196 $ 56 $ 64 $ 4 $ 29 $ 24 $ 3 $ 1 $ 5 Allowance for credit losses 100 46 24 17 4 9 5 2 2 Other decommissioning-related activity (a) (636) (636) — — — — — — — Energy-related options (b) 20 20 — — — — — — — True-up adjustments to decoupling mechanisms and formula rates (c) (176) — (64) (17) (8) (88) (46) (19) (23) Long-term incentive plan 62 — — — — — — — — Amortization of operating ROU asset 83 51 1 — 15 14 3 5 2 AFUDC — Equity (64) — (13) (12) (14) (25) (20) (3) (2) Six Months Ended June 30, 2020 Pension and non-pension postretirement benefit costs $ 203 $ 58 $ 57 $ 3 $ 31 $ 35 $ 7 $ 4 $ 7 Allowance for credit losses 92 13 17 29 10 22 12 8 2 Other decommissioning-related activity (a) (60) (60) — — — — — — — Energy-related options (b) 27 27 — — — — — — — True-up adjustments to decoupling mechanisms and formula rates (c) 55 — 13 (5) — 47 (2) 24 25 Long-term incentive plan (10) — — — — — — — — Amortization of operating ROU asset 112 80 1 — 15 14 3 4 2 Deferred Prosecution Agreement payments (d) 200 — 200 — — — — — — AFUDC — Equity (49) — (14) (7) (10) (17) (13) (2) (2) __________ (a) Includes the elimination of decommissioning-related activities for the Regulatory Agreement Units except for decommissioning-related impacts that were not offset for the Byron units in the second quarter of 2021, including the elimination of operating revenues, ARO accretion, ARC amortization, investment income, and income taxes related to all NDT fund activity for these units. See Note 10 — Asset Retirement Obligations of the Exelon 2020 Form 10-K for additional information regarding the accounting for nuclear decommissioning and Note 8 — Nuclear Decommissioning for additional information on the contractual offset suspension for the Byron units. (b) Includes option premiums reclassified to realized at the settlement of the underlying contracts and recorded to results of operations. (c) For ComEd, reflects the true-up adjustments in regulatory assets and liabilities associated with its distribution, energy efficiency, distributed generation, and transmission formula rates. For BGE, Pepco, and DPL, reflects the change in regulatory assets and liabilities associated with their decoupling mechanisms and transmission formula rates. For PECO and ACE, reflects the change in regulatory assets and liabilities associated with their transmission formula rates. See Note 3 — Regulatory Matters for additional information. (d) See Note 15 — Commitments and Contingencies for additional information related to the Deferred Prosecution Agreement. The following tables provide a reconciliation of cash, cash equivalents and restricted cash reported within the Registrants’ Consolidated Balance Sheets that sum to the total of the same amounts in their Consolidated Statements of Cash Flows. Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE June 30, 2021 Cash and cash equivalents $ 1,578 $ 542 $ 71 $ 376 $ 368 $ 61 $ 17 $ 17 $ 11 Restricted cash and cash equivalents 379 59 240 8 3 42 33 5 3 Restricted cash included in other long-term assets 52 — 43 — — 9 — — 9 Total cash, restricted cash, and cash equivalents $ 2,009 $ 601 $ 354 $ 384 $ 371 $ 112 $ 50 $ 22 $ 23 December 31, 2020 Cash and cash equivalents $ 663 $ 226 $ 83 $ 19 $ 144 $ 111 $ 30 $ 15 $ 17 Restricted cash and cash equivalents 438 89 279 7 1 39 35 — 3 Restricted cash included in other long-term assets 53 — 43 — — 10 — — 10 Cash, restricted cash, and cash equivalents - Held for Sale 12 12 — — — — — — — Total cash, restricted cash, and cash equivalents $ 1,166 $ 327 $ 405 $ 26 $ 145 $ 160 $ 65 $ 15 $ 30 June 30, 2020 Cash and cash equivalents $ 2,129 $ 483 $ 403 $ 380 $ 195 $ 39 $ 19 $ 6 $ 8 Restricted cash and cash equivalents 373 153 155 7 1 36 33 — 3 Restricted cash included in other long-term assets 178 — 166 — — 11 — — 11 Total cash, restricted cash, and cash equivalents $ 2,680 $ 636 $ 724 $ 387 $ 196 $ 86 $ 52 $ 6 $ 22 December 31, 2019 Cash and cash equivalents $ 587 $ 303 $ 90 $ 21 $ 24 $ 131 $ 30 $ 13 $ 12 Restricted cash and cash equivalents 358 146 150 6 1 36 33 — 2 Restricted cash included in other long-term assets 177 — 163 — — 14 — — 14 Total cash, restricted cash, and cash equivalents $ 1,122 $ 449 $ 403 $ 27 $ 25 $ 181 $ 63 $ 13 $ 28 For additional information on restricted cash see Note 1 — Significant Accounting Policies of the Exelon 2020 Form 10-K. Supplemental Balance Sheet Information The following tables provide additional information about material items recorded in the Registrants' Consolidated Balance Sheets. Accrued expenses Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE June 30, 2021 Compensation-related accruals (a) $ 730 $ 255 $ 136 $ 51 $ 55 $ 85 $ 28 $ 16 $ 13 Taxes accrued 473 242 77 31 35 86 58 9 9 Interest accrued 339 43 116 40 45 51 27 8 12 December 31, 2020 Compensation-related accruals (a) $ 1,069 $ 426 $ 170 $ 73 $ 84 $ 109 $ 36 $ 18 $ 17 Taxes accrued 527 229 94 16 73 117 90 18 12 Interest accrued 331 44 109 37 46 51 26 7 12 __________ (a) Primarily includes accrued payroll, bonuses and other incentives, vacation and benefits.

Related Party Transactions (All

Related Party Transactions (All Registrants)	6 Months Ended
Related Party Transactions (All Registrants)	Jun. 30, 2021
Related Party Transactions [Abstract]
Related Party Transactions (All Registrants)	Related Party Transactions (All Registrants) Operating revenues from affiliates Generation The following table presents Generation’s Operating revenues from affiliates, which are primarily recorded as Purchased power from affiliates and an immaterial amount recorded as Operating and maintenance expense from affiliates at the Utility Registrants: Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 Operating revenues from affiliates: ComEd (a)(b) $ 75 $ 80 $ 153 $ 170 PECO (c) 41 41 83 78 BGE (d) 58 70 130 169 PHI 77 78 176 182 Pepco (e) 55 60 130 139 DPL (f) 17 16 37 38 ACE (g) 5 2 9 5 Other 3 2 7 2 Total operating revenues from affiliates (Generation) $ 254 $ 271 $ 549 $ 601 __________ (a) Generation has an ICC-approved RFP contract with ComEd to provide a portion of ComEd’s electricity supply requirements. Generation also sells RECs and ZECs to ComEd. (b) For the three and six months ended June 30, 2021, respectively, ComEd’s Purchased power from Generation of $78 million and $163 million is recorded as Operating revenues from ComEd of $75 million and $153 million and as Purchased power and fuel from ComEd of $3 million and $10 million at Generation. For the three and six months ended June 30, 2020 , respectively, ComEd’s Purchased power from Generation of $84 million and $181 million is recorded as Operating revenues from ComEd of $80 million and $170 million and as Purchased power and fuel from ComEd of $4 million and $11 million at Generation. (c) Generation provides electric supply to PECO under contracts executed through PECO’s competitive procurement process. In addition, Generation has a ten-year agreement with PECO to sell solar AECs. (d) Generation provides a portion of BGE’s energy requirements under its MDPSC-approved market-based SOS and gas commodity programs. (e) Generation provides electric supply to Pepco under contracts executed through Pepco's competitive procurement process approved by the MDPSC and DCPSC. (f) Generation provides a portion of DPL's energy requirements under its MDPSC and DPSC-approved market-based SOS commodity programs. (g) Generation provides electric supply to ACE under contracts executed through ACE's competitive procurement process. PHI PHI’s Operating revenues from affiliates are primarily with BSC for services that PHISCO provides to BSC. Service Company Costs for Corporate Support The Registrants receive a variety of corporate support services from BSC. Pepco, DPL, and ACE also receive corporate support services from PHISCO. See Note 1 - Significant Accounting Policies for additional information regarding BSC and PHISCO. The following table presents the service company costs allocated to the Registrants: Operating and maintenance from affiliates Capitalized costs Three Months Ended June 30, Six Months Ended June 30, Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 2021 2020 2021 2020 Exelon BSC $ 124 $ 129 $ 282 $ 242 PHISCO 17 16 36 30 Generation BSC $ 135 $ 133 $ 280 $ 273 10 14 33 25 ComEd BSC 72 67 143 138 45 41 102 83 PECO BSC 40 36 80 73 17 18 44 33 BGE BSC 45 40 88 82 20 30 43 58 PHI BSC 37 35 76 72 32 26 60 43 PHISCO — — — — 17 16 36 30 Pepco BSC 23 20 45 41 13 9 25 15 PHISCO 28 32 57 62 7 7 15 13 DPL BSC 15 13 29 26 10 9 19 14 PHISCO 24 25 49 49 5 5 11 9 ACE BSC 12 11 24 21 8 8 15 12 PHISCO 21 23 43 44 5 4 10 8 Current Receivables from/Payables to affiliates The following tables present current receivables from affiliates and current payables to affiliates: June 30, 2021 Receivables from affiliates: Payables to affiliates: Generation ComEd PECO BGE Pepco DPL ACE BSC PHISCO Other Total Generation $ 20 $ — $ — $ — $ — $ — $ 84 $ — $ 15 $ 119 ComEd $ 52 (a) — — — — — 50 — 7 109 PECO 22 — — — — — 24 — 4 50 BGE 8 — — — — — 31 — 2 41 PHI — — — — — — — 4 — 10 14 Pepco 12 — — — — — 14 14 2 42 DPL 3 — — — — — 9 10 1 23 ACE 12 — — — — — 8 10 — 30 Other 8 2 — — — — 1 — — 11 Total $ 117 $ 22 $ — $ — $ — $ — $ 1 $ 224 $ 34 $ 41 $ 439 December 31, 2020 Receivables from affiliates: Payables to affiliates: Generation ComEd PECO BGE Pepco DPL ACE BSC PHISCO Other Total Generation $ 13 $ — $ — $ — $ — $ — $ 72 $ — $ 22 $ 107 ComEd $ 78 (a) — — — — — 59 — 9 146 PECO 17 1 — — — — 28 — 4 50 BGE 11 — — — — — 47 — 3 61 PHI — — — — — — — 4 — 11 15 Pepco 13 2 — 1 — — 25 14 — 55 DPL 3 1 — — — — 21 10 1 36 ACE 6 — — — — — 15 9 1 31 Other 25 5 2 2 2 1 6 — — 43 Total $ 153 $ 22 $ 2 $ 3 $ 2 $ 1 $ 6 $ 271 $ 33 $ 51 $ 544 __________ (a) As of June 30, 2021 and December 31, 2020, Generation had a contract liability with ComEd for $7 million and $50 million, respectively, that was included in Other current liabilities on Generation’s Consolidated Balance Sheets. At June 30, 2021 and December 31, 2020, ComEd had a Current Payable to Generation of $45 million and $28 million, respectively, on its Consolidated Balance Sheets, which consisted of Generation’s Current Receivable from ComEd, partially offset by Generation’s contract liability with ComEd. Borrowings from Exelon/PHI intercompany money pool To provide an additional short-term borrowing option that will generally be more favorable to the borrowing participants than the cost of external financing both Exelon and PHI operate an intercompany money pool. Generation, ComEd, PECO, and PHI Corporate participate in the Exelon money pool. Pepco, DPL, and ACE participate in the PHI intercompany money pool. Noncurrent Receivables from/Payables to affiliates Generation has long-term payables to ComEd and PECO as a result of the nuclear decommissioning contractual construct whereby, to the extent NDT funds are greater than the underlying ARO at the end of decommissioning, such amounts are due back to ComEd and PECO, as applicable, for payment to their respective customers. See Note 10 — Asset Retirement Obligations of the Exelon 2020 Form 10-K for additional information. The following table presents noncurrent receivables from affiliates at ComEd and PECO which are recorded as noncurrent payables to affiliates at Generation: June 30, 2021 December 31, 2020 ComEd $ 2,439 $ 2,541 PECO 571 475 Long-term debt to financing trusts The following table presents Long-term debt to financing trusts: June 30, 2021 December 31, 2020 Exelon ComEd PECO Exelon ComEd PECO ComEd Financing III $ 206 $ 205 $ — $ 206 $ 205 $ — PECO Trust III 81 — 81 81 — 81 PECO Trust IV 103 — 103 103 — 103 Total $ 390 $ 205 $ 184 $ 390 $ 205 $ 184 Long-term debt to affiliates In connection with the debt obligations assumed by Exelon as part of the Constellation merger, Exelon and subsidiaries of Generation (former Constellation subsidiaries) assumed intercompany loan agreements that mirror the terms and amounts of the third-party debt obligations of Exelon, resulting in intercompany notes payable included in Long-term debt to affiliates in Generation’s Consolidated Balance Sheets and intercompany notes receivable at Exelon Corporate.

Planned Separation

Planned Separation	6 Months Ended
Planned Separation	Jun. 30, 2021
Discontinued Operations and Disposal Groups [Abstract]
Planned Separation	Planned SeparationOn February 21, 2021, Exelon’s Board of Directors approved a plan to separate the Utility Registrants and Generation, creating two publicly traded companies. Under the separation plan, Exelon shareholders will retain their current shares of Exelon stock and receive a pro-rata distribution of shares of the new company’s stock in a transaction that is expected to be tax-free to Exelon and its shareholders for U.S. federal income tax purposes. The actual number of shares to be distributed to Exelon shareholders will be determined prior to closing.

Significant Accounting Polici_2

Significant Accounting Policies (Policies)	6 Months Ended
Significant Accounting Policies (Policies)	Jun. 30, 2021
Accounting Policies [Abstract]
Description of Business and Basis of Presentation (All Registrants) [Policy Text Block]	Description of Business (All Registrants) Exelon is a utility services holding company engaged in the generation, delivery and marketing of energy through Generation and the energy distribution and transmission businesses through ComEd, PECO, BGE, Pepco, DPL, and ACE. Name of Registrant Business Service Territories Exelon Generation Generation, physical delivery and marketing of power across multiple geographical regions through its customer-facing business, Constellation, which sells electricity to both wholesale and retail customers. Generation also sells natural gas, renewable energy, and other energy-related products and services. Five reportable segments: Mid-Atlantic, Midwest, New York, ERCOT, and Other Power Regions Commonwealth Edison Company Purchase and regulated retail sale of electricity Northern Illinois, including the City of Chicago Transmission and distribution of electricity to retail customers PECO Energy Company Purchase and regulated retail sale of electricity and natural gas Southeastern Pennsylvania, including the City of Philadelphia (electricity) Transmission and distribution of electricity and distribution of natural gas to retail customers Pennsylvania counties surrounding the City of Philadelphia (natural gas) Baltimore Gas and Electric Company Purchase and regulated retail sale of electricity and natural gas Central Maryland, including the City of Baltimore (electricity and natural gas) Transmission and distribution of electricity and distribution of natural gas to retail customers Pepco Holdings LLC Utility services holding company engaged, through its reportable segments Pepco, DPL, and ACE Service Territories of Pepco, DPL, and ACE Potomac Electric Purchase and regulated retail sale of electricity District of Columbia, and major portions of Montgomery and Prince George’s Counties, Maryland Transmission and distribution of electricity to retail customers Delmarva Power & Purchase and regulated retail sale of electricity and natural gas Portions of Delaware and Maryland (electricity) Transmission and distribution of electricity and distribution of natural gas to retail customers Portions of New Castle County, Delaware (natural gas) Atlantic City Electric Company Purchase and regulated retail sale of electricity Portions of Southern New Jersey Transmission and distribution of electricity to retail customers Basis of Presentation (All Registrants) This is a combined quarterly report of all Registrants. The Notes to the Consolidated Financial Statements apply to the Registrants as indicated parenthetically next to each corresponding disclosure. When appropriate, the Registrants are named specifically for their related activities and disclosures. Each of the Registrant’s Consolidated Financial Statements includes the accounts of its subsidiaries. All intercompany transactions have been eliminated. Through its business services subsidiary, BSC, Exelon provides its subsidiaries with a variety of support services at cost, including legal, human resources, financial, information technology, and supply management services. PHI also has a business services subsidiary, PHISCO, which provides a variety of support services at cost, including legal, accounting, engineering, customer operations, distribution and transmission planning, asset management, system operations, and power procurement, to PHI operating companies. The costs of BSC and PHISCO are directly charged or allocated to the applicable subsidiaries. The results of Exelon’s corporate operations are presented as “Other” within the consolidated financial statements and include intercompany eliminations unless otherwise disclosed. The accompanying consolidated financial statements as of June 30, 2021 and for the three and six months ended June 30, 2021 and 2020 are unaudited but, in the opinion of the management of each Registrant include all adjustments that are considered necessary for a fair statement of the Registrants’ respective financial statements in accordance with GAAP. All adjustments are of a normal, recurring nature, except as otherwise
Revenue [Policy Text Block]	The Registrants recognize revenue from contracts with customers to depict the transfer of goods or services to customers at an amount that the entities expect to be entitled to in exchange for those goods or services. Generation’s primary sources of revenue include competitive sales of power, natural gas, and other energy-related products and services. The Utility Registrants’ primary sources of revenue include regulated electric and gas tariff sales, distribution, and transmission services.

Regulatory Matters (Tables)

Regulatory Matters (Tables)	6 Months Ended
Regulatory Matters (Tables)	Jun. 30, 2021
Regulated Operations [Abstract]
Public Utilities Distribution Rate Cases [Table Text Block]	The following tables show the completed and pending distribution base rate case proceedings in 2021. Completed Distribution Base Rate Case Proceedings Registrant/Jurisdiction Filing Date Service Requested Revenue Requirement (Decrease) Increase Approved Revenue Requirement (Decrease) Increase Approved ROE Approval Date Rate Effective Date ComEd - Illinois (a) April 16, 2020 Electric $ (11) $ (14) 8.38 % December 9, 2020 January 1, 2021 PECO - Pennsylvania September 30, 2020 Natural Gas 69 29 10.24 % June 22, 2021 July 1, 2021 BGE - Maryland (b) May 15, 2020 (amended September 11, 2020) Electric 203 140 9.50 % December 16, 2020 January 1, 2021 Natural Gas 108 74 9.65 % Pepco - District of Columbia (c) May 30, 2019 (amended June 1, 2020) Electric 136 109 9.275 % June 8, 2021 July 1, 2021 Pepco - Maryland (d) October 26, 2020 (amended March 31, 2021) Electric 104 52 9.55 % June 28, 2021 June 28, 2021 ACE - New Jersey (e) December 9, 2020 (amended February 26, 2021) Electric 67 41 9.60 % July 14, 2021 January 1, 2022 __________ (a) ComEd's 2021 approved revenue requirement reflects an increase of $50 million for the initial year revenue requirement for 2021 and a decrease of $64 million related to the annual reconciliation for 2019. The revenue requirement for 2021 and the revenue requirement for 2019 provide for a weighted average debt and equity return on distribution rate base of 6.28%, inclusive of an allowed ROE of 8.38%, reflecting the monthly average yields for 30-year treasury bonds plus 580 basis points. (b) Reflects a three-year cumulative multi-year plan for 2021 through 2023. The MDPSC awarded BGE electric revenue requirement increases of $59 million, $39 million, and $42 million, before offsets, in 2021, 2022, and 2023, respectively, and natural gas revenue requirement increases of $53 million, $11 million, and $10 million, before offsets, in 2021, 2022, and 2023, respectively. BGE proposed to use certain tax benefits to fully offset the increases in 2021 and 2022 and partially offset the increase in 2023. However, the MDPSC only utilized the tax benefits to fully offset the increases in 2021 such that customer rates will remain unchanged from 2020 to 2021. The MDPSC has deferred a decision on whether to use certain tax benefits to offset the customer rate increases in 2022 and 2023 and BGE cannot predict the outcome. (c) Reflects a cumulative multi-year plan with 18-months remaining in 2021 through 2022. The DCPSC awarded Pepco electric incremental revenue requirement increases of $42 million and $67 million, before offsets, for the remainder of 2021 and 2022, respectively. However, the DCPSC utilized the acceleration of refunds for certain tax benefits along with other rate relief to partially offset the customer rate increases by $22 million and $40 million for the remainder of 2021 and 2022, respectively. (d) Reflects a three-year cumulative multi-year plan for April 1, 2021 through March 31, 2024. The MDPSC awarded Pepco electric incremental revenue requirement increases of $21 million, $16 million, and $15 million, before offsets, for the 12-month periods ending March 31, 2022, 2023, and 2024, respectively. Pepco proposed to utilize certain tax benefits to fully offset the increase through 2023 and partially offset customer rate increases in 2024. However, the MDPSC only utilized the acceleration of refunds for certain tax benefits to fully offset the increases such that customer rates remain unchanged through March 31, 2022. The MDPSC has deferred decision on whether to use additional tax benefits to offset customer rate increases for periods after March 31, 2022 and Pepco cannot predict the outcome. (e) Requested and approved increases are before New Jersey sales and use tax. The order allows ACE to retain approximately $11 million of certain tax benefits which will result in a decrease to income tax expense within Exelon's, PHI's, and ACE's Consolidated Statements of Operations and Comprehensive Income in the third quarter of 2021. Pending Distribution Base Rate Case Proceedings Registrant/Jurisdiction Filing Date Service Requested Revenue Requirement Increase Requested ROE Expected Approval Timing ComEd - Illinois (a) April 16, 2021 Electric $ 51 7.36 % Fourth quarter of 2021 PECO - Pennsylvania March 30, 2021 Electric 246 10.95 % Fourth quarter of 2021 DPL - Delaware (b) March 6, 2020 (amended February 2, 2021) Electric 23 10.3 % Third quarter of 2021 __________ (a) ComEd's 2022 requested revenue requirement reflects an increase of $40 million for the initial year revenue requirement for 2022 and an increase of $11 million related to the annual reconciliation for 2020. The revenue requirement for 2022 provides for a weighted average debt and equity return on distribution rate base of 5.72%, inclusive of an allowed ROE of 7.36%, reflecting the average monthly yields for 30-year treasury bonds plus 580 basis points. The reconciliation revenue requirement for 2020 provides for a weighted average debt and equity return on distribution rate base of 5.69%, inclusive of an allowed ROE of 7.29%, reflecting the average monthly yields for 30-year treasury bonds plus 580 basis points less a performance metrics penalty of 7 basis points. (b) The rates went into effect on October 6, 2020, subject to refund.
Public Utilities Transmission Rate Filings [Table Text Block]	The Utility Registrants' transmission rates are each established based on a FERC-approved formula. ComEd, BGE, Pepco, DPL, and ACE are required to file an annual update to the FERC-approved formula on or before May 15, and PECO is required to file on or before May 31, with the resulting rates effective on June 1 of the same year. The annual update for ComEd is based on prior year actual costs and current year projected capital additions (initial year revenue requirement). The annual update for PECO is based on prior year actual costs and current year projected capital additions, accumulated depreciation, and accumulated deferred income taxes. The annual update for BGE, Pepco, DPL, and ACE is based on prior year actual costs and current year projected capital additions, accumulated depreciation, depreciation and amortization expense, and accumulated deferred income taxes. The update for ComEd also reconciles any differences between the revenue requirement in effect beginning June 1 of the prior year and actual costs incurred for that year (annual reconciliation). The update for PECO, BGE, Pepco, DPL, and ACE also reconciles any differences between the actual costs and actual revenues for the calendar year (annual reconciliation). For 2021, the following total increases/(decreases) were included in the Utility Registrants’ electric transmission formula rate updates: Registrant (a) Initial Revenue Requirement Increase (Decrease) Annual Reconciliation Increase Total Revenue Requirement Increase (b) Allowed Return on Rate Base (c) Allowed ROE (d) ComEd $ 33 $ 12 $ 45 8.20 % 11.50 % PECO (2) 26 24 7.37 % 10.35 % BGE 38 27 65 7.35 % 10.50 % Pepco (9) 21 12 7.68 % 10.50 % DPL 19 33 52 7.20 % 10.50 % ACE 27 24 51 7.45 % 10.50 % __________ (a) All rates are effective June 1, 2021 - May 31, 2022, subject to review by interested parties pursuant to review protocols of each Utility Registrants' tariff. (b) In 2020, ComEd, BGE, Pepco, DPL, and ACE's transmission revenue requirement included a one-time decrease in accordance with the April 24, 2020 settlement agreement related to excess deferred income taxes which now completed has resulted in an increase to the 2021 transmission revenue requirement. In 2020, PECO's transmission revenue requirement included a one-time decrease in accordance with the December 5, 2019 settlement agreement related to refunds which now completed has resulted in an increase to the 2021 transmission revenue requirement. (c) Represents the weighted average debt and equity return on transmission rate bases. (d) As part of the FERC-approved settlements of ComEd’s 2007 and PECO's 2017 rate cases, the rate of return on common equity is 11.50% and 10.35%, respectively, inclusive of a 50-basis-point incentive adder for being a member of a RTO, and
Public Utilities Energy Efficiency Revenue [Table Text Block]	Energy Efficiency Formula Rate (Exelon and ComEd). ComEd filed its annual energy efficiency formula rate update with the ICC on June 1, 2021. The filing establishes the revenue requirement used to set the rates that will take effect in January 2022 after the ICC’s review and approval. The requested revenue requirement update is based on a reconciliation of the 2020 actual costs plus projected 2022 expenditures. Initial Revenue Requirement Increase Annual Reconciliation Decrease Total Revenue Requirement Increase Requested Return on Rate Base (a) Requested ROE $ 55 $ (1) $ 54 5.72 % 7.36 % __________
Public Utilities General Disclosures [Table Text Block]	The following table presents authorized amounts capitalized for ratemaking purposes related to earnings on shareholders’ investment that are not recognized for financial reporting purposes in Exelon's and the Utility Registrant's Consolidated Balance Sheets. These amounts will be recognized as revenues in the related Consolidated Statements of Operations and Comprehensive Income in the periods they are billable to the Utility Registrants' customers. Exelon ComEd (a) PECO BGE (b) PHI Pepco (c) DPL (c) ACE June 30, 2021 $ 48 $ 1 $ — $ 41 $ 6 $ 3 $ 3 $ — December 31, 2020 51 (1) — 45 7 4 3 — __________ (a) Reflects ComEd's unrecognized equity returns/(losses) earned/(incurred) for ratemaking purposes on its electric distribution formula rate regulatory assets. (b) BGE's authorized amounts capitalized for ratemaking purposes primarily relate to earnings on shareholders' investment on its AMI programs. (c) Pepco's and DPL's authorized amounts capitalized for ratemaking purposes relate to earnings on shareholders' investment on their respective AMI Programs and Energy Efficiency and Demand Response Programs. The earnings on energy efficiency are on Pepco DC and DPL DE programs only.

Revenue from Contracts with C_2

Revenue from Contracts with Customers (Tables)	6 Months Ended
Revenue from Contracts with Customers (Tables)	Jun. 30, 2021
Contracts with Customers [Line Items]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Table Text Block]	The following table shows the amounts of future revenues expected to be recorded in each year for performance obligations that are unsatisfied or partially unsatisfied as of June 30, 2021. This disclosure only includes contracts for which the total consideration is fixed and determinable at contract inception. The average contract term varies by customer type and commodity but ranges from one month to several years. This disclosure excludes Generation's power and gas sales contracts as they contain variable volumes and/or variable pricing. This disclosure also excludes the Utility Registrants' gas and electric tariff sales contracts and transmission revenue contracts as they generally have an original expected duration of one year or less and, therefore, do not contain any future, unsatisfied performance obligations to be included in this disclosure. 2021 2022 2023 2024 2025 and thereafter Total Exelon $ 149 $ 100 $ 46 $ 31 $ 180 $ 506 Generation 223 146 54 29 94 546 PHI 5 8 8 6 86 113 Pepco 3 6 6 5 71 91 DPL 1 1 1 — 8 11 ACE 1 1 1 1 7 11
Contract Assets [Member]
Contracts with Customers [Line Items]
Contract with Customer, Contract Asset, Contract Liability, and Receivable [Table Text Block]	The following table provides a rollforward of the contract assets reflected in Exelon's and Generation's Consolidated Balance Sheets for the three and six months ended June 30, 2021 and 2020. The Utility Registrants do not have any contract assets. Exelon Generation Balance as of December 31, 2020 $ 144 $ 144 Amounts reclassified to receivables (16) (16) Revenues recognized 13 13 Amounts previously held-for-sale 12 12 Balance as of March 31, 2021 153 153 Amounts reclassified to receivables (12) (12) Revenues recognized 9 9 Balance as of June 30, 2021 $ 150 $ 150 Exelon Generation Balance as of December 31, 2019 $ 174 $ 174 Amounts reclassified to receivables (19) (19) Revenues recognized 17 17 Balance as of March 31, 2020 172 172 Amounts reclassified to receivables (26) (26) Revenues recognized 13 13 Balance as of June 30, 2020 $ 159 $ 159
Contract Liabilities [Member]
Contracts with Customers [Line Items]
Contract with Customer, Contract Asset, Contract Liability, and Receivable [Table Text Block]	The following table provides a rollforward of the contract liabilities reflected in Exelon's, Generation's, PHI's, Pepco's, DPL's, and ACE's Consolidated Balance Sheets for the three and six months ended June 30, 2021 and 2020. As of June 30, 2021 and December 31, 2020, ComEd's, PECO's, and BGE's contract liabilities were immaterial. Exelon Generation PHI Pepco DPL ACE Balance as of December 31, 2020 $ 151 $ 84 $ 118 $ 94 $ 12 $ 12 Consideration received or due 20 31 — — — — Revenues recognized (27) (64) (2) (2) — — Amounts previously held-for-sale 3 3 — — — — Balance as of March 31, 2021 147 54 116 92 12 12 Consideration received or due 17 39 — — — — Revenues recognized (32) (68) (3) (1) (1) (1) Balance as of June 30, 2021 $ 132 $ 25 $ 113 $ 91 $ 11 $ 11 Exelon Generation PHI Pepco DPL ACE Balance as of December 31, 2019 $ 33 $ 71 $ — $ — $ — $ — Consideration received or due 20 55 — — — — Revenues recognized (24) (70) — — — — Balance as of March 31, 2020 29 56 — — — — Consideration received or due 13 34 — — — — Revenues recognized (22) (63) — — — — Balance as of June 30, 2020 $ 20 $ 27 $ — $ — $ — $ — The following table reflects revenues recognized in the three and six months ended June 30, 2021 and 2020, which were included in contract liabilities at December 31, 2020 and 2019, respectively: Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 Exelon $ 17 $ 14 $ 34 $ 23 Generation 41 42 79 61 PHI 3 — 5 — Pepco 1 — 3 — DPL 1 — 1 — ACE 1 — 1 —

Segment Information (Tables)

Segment Information (Tables)	6 Months Ended
Segment Information (Tables)	Jun. 30, 2021
Segment Tables [Line Items]
Analysis and reconciliation of reportable segment information	An analysis and reconciliation of the Registrants’ reportable segment information to the respective information in the consolidated financial statements for the three and six months ended June 30, 2021 and 2020 is as follows: Three Months Ended June 30, 2021 and 2020 Generation ComEd PECO BGE PHI Other (a) Intersegment Exelon Operating revenues (b) : 2021 Competitive businesses electric revenues $ 3,747 $ — $ — $ — $ — $ — $ (250) $ 3,497 Competitive businesses natural gas revenues 507 — — — — — — 507 Competitive businesses other revenues (101) — — — — — (3) (104) Rate-regulated electric revenues — 1,517 610 558 1,113 — (11) 3,787 Rate-regulated natural gas revenues — — 83 124 24 — (3) 228 Shared service and other revenues — — — — 3 524 (527) — Total operating revenues $ 4,153 $ 1,517 $ 693 $ 682 $ 1,140 $ 524 $ (794) $ 7,915 2020 Competitive businesses electric revenues $ 3,414 $ — $ — $ — $ — $ — $ (268) $ 3,146 Competitive businesses natural gas revenues 353 — — — — — — 353 Competitive businesses other revenues 113 — — — — — (1) 112 Rate-regulated electric revenues — 1,417 586 504 983 — (15) 3,475 Rate-regulated natural gas revenues — — 95 112 30 — (1) 236 Shared service and other revenues — — — — 3 472 (475) — Total operating revenues $ 3,880 $ 1,417 $ 681 $ 616 $ 1,016 $ 472 $ (760) $ 7,322 Generation ComEd PECO BGE PHI Other (a) Intersegment Exelon Intersegment revenues (c) : 2021 $ 254 $ 5 $ 2 $ 7 $ 4 $ 522 $ (794) $ — 2020 271 11 2 4 3 470 (760) 1 Depreciation and amortization: 2021 $ 930 $ 296 $ 87 $ 141 $ 194 $ 18 $ — $ 1,666 2020 300 274 88 129 191 19 — 1,001 Operating expenses: 2021 $ 4,469 $ 1,196 $ 552 $ 620 $ 955 $ 537 $ (768) $ 7,561 2020 3,547 1,345 618 573 956 478 (748) 6,769 Interest expense, net: 2021 $ 76 $ 98 $ 42 $ 34 $ 67 $ 79 $ — $ 396 2020 87 98 36 32 67 107 — 427 Income (loss) before income taxes: 2021 $ 124 $ 238 $ 106 $ 37 $ 138 $ (92) $ — $ 551 2020 860 (15) 32 17 7 (108) 1 794 Income Taxes: 2021 $ 110 $ 46 $ 2 $ (8) $ (3) $ (73) $ — $ 74 2020 329 46 (7) (22) (87) (40) — 219 Net income (loss): 2021 $ 13 $ 192 $ 104 $ 45 $ 141 $ (19) $ — $ 476 2020 529 (61) 39 39 94 (67) 1 574 Capital Expenditures: 2021 $ 337 $ 549 $ 282 $ 284 $ 433 $ 15 $ — $ 1,900 2020 372 523 253 265 310 34 — 1,757 (a) Other primarily includes Exelon’s corporate operations, shared service entities, and other financing and investment activities. (b) Includes gross utility tax receipts from customers. The offsetting remittance of utility taxes to the governing bodies is recorded in expenses in the Registrants’ Consolidated Statements of Operations and Comprehensive Income. See Note 18— Supplemental Financial Information for additional information on total utility taxes. (c) Intersegment revenues exclude sales to unconsolidated affiliates. The intersegment profit associated with Generation’s sale of certain products and services by and between Exelon’s segments is not eliminated in consolidation due to the recognition of intersegment profit in accordance with regulatory accounting guidance. For Exelon, these amounts are included in Operating revenues in the Consolidated Statements of Operations and Comprehensive Income. See Note 19— Related Party Transactions for additional information on intersegment revenues. PHI: Pepco DPL ACE Other (a) Intersegment PHI Operating revenues (b) : 2021 Rate-regulated electric revenues $ 523 $ 274 $ 319 $ — $ (3) $ 1,113 Rate-regulated natural gas revenues — 24 — — — 24 Shared service and other revenues — — — 95 (92) 3 Total operating revenues $ 523 $ 298 $ 319 $ 95 $ (95) $ 1,140 2020 Rate-regulated electric revenues $ 494 $ 237 $ 256 $ — $ (4) $ 983 Rate-regulated natural gas revenues — 30 — — — 30 Shared service and other revenues — — — 97 (94) 3 Total operating revenues $ 494 $ 267 $ 256 $ 97 $ (98) $ 1,016 Intersegment revenues (c) : 2021 $ 1 $ 2 $ 1 $ 95 $ (95) $ 4 2020 1 2 1 97 (98) 3 Depreciation and amortization: 2021 $ 96 $ 51 $ 40 $ 7 $ — $ 194 2020 92 47 44 8 — 191 Operating expenses: 2021 $ 429 $ 255 $ 269 $ 97 $ (95) $ 955 2020 436 263 258 97 (98) 956 Interest expense, net: 2021 $ 35 $ 16 $ 14 $ 2 $ — $ 67 2020 34 15 15 3 — 67 Income (loss) before income taxes: 2021 $ 72 $ 31 $ 36 $ (1) $ — $ 138 2020 33 (9) (15) (2) — 7 Income Taxes: 2021 $ (3) $ 1 $ (1) $ — $ — $ (3) 2020 (24) (28) (33) (2) — (87) Net income (loss): 2021 $ 75 $ 30 $ 37 $ (1) $ — $ 141 2020 57 19 18 — — 94 Capital Expenditures: 2021 $ 219 $ 99 $ 116 $ (1) $ — $ 433 2020 144 89 77 — — 310 __________ (a) Other primarily includes PHI’s corporate operations, shared service entities, and other financing and investment activities. (b) Includes gross utility tax receipts from customers. The offsetting remittance of utility taxes to the governing bodies is recorded in expenses in the Registrants’ Consolidated Statements of Operations and Comprehensive Income. See Note 18— Supplemental Financial Information for additional information on total utility taxes. (c) Includes intersegment revenues with ComEd, BGE, and PECO, which are eliminated at Exelon.
Analysis and reconciliation of reportable segment revenues for Generation	The following tables disaggregate the Registrants' revenue recognized from contracts with customers into categories that depict how the nature, amount, timing, and uncertainty of revenue and cash flows are affected by economic factors. For Generation, the disaggregation of revenues reflects Generation’s two primary products of power sales and natural gas sales, with further disaggregation of power sales provided by geographic region. For the Utility Registrants, the disaggregation of revenues reflects the two primary utility services of rate-regulated electric sales and rate-regulated natural gas sales (where applicable), with further disaggregation of these tariff sales provided by major customer groups. Exelon’s disaggregated revenues are consistent with Generation and the Utility Registrants, but exclude any intercompany revenues. Competitive Business Revenues (Generation): Three Months Ended June 30, 2021 Revenues from external customers (a) Intersegment Total Contracts with customers Other (b) Total Mid-Atlantic $ 1,062 $ 24 $ 1,086 $ 5 $ 1,091 Midwest 975 (13) 962 — 962 New York 376 5 381 — 381 ERCOT 179 92 271 4 275 Other Power Regions 921 126 1,047 (9) 1,038 Total Competitive Businesses Electric Revenues 3,513 234 3,747 — 3,747 Competitive Businesses Natural Gas Revenues 253 254 507 — 507 Competitive Businesses Other Revenues (c) 107 (208) (101) — (101) Total Generation Consolidated Operating Revenues $ 3,873 $ 280 $ 4,153 $ — $ 4,153 Three Months Ended June 30, 2020 Revenues from external customers (a) Intersegment Total Contracts with customers Other (b) Total Mid-Atlantic $ 1,100 $ (35) $ 1,065 $ 9 $ 1,074 Midwest 855 107 962 — 962 New York 336 5 341 (1) 340 ERCOT 175 52 227 7 234 Other Power Regions 776 43 819 (15) 804 Total Competitive Businesses Electric Revenues 3,242 172 3,414 — 3,414 Competitive Businesses Natural Gas Revenues 209 144 353 — 353 Competitive Businesses Other Revenues (c) 86 27 113 — 113 Total Generation Consolidated Operating Revenues $ 3,537 $ 343 $ 3,880 $ — $ 3,880 __________ (a) Includes all wholesale and retail electric sales to third parties and affiliated sales to the Utility Registrants. (b) Includes revenues from derivatives and leases. (c) Other represents activities not allocated to a region. See text above for a description of included activities. Includes unrealized mark-to-market losses of $239 million and gains of $21 million in 2021 and 2020, respectively, and elimination of intersegment revenues. Revenues net of purchased power and fuel expense (Generation): Three Months Ended June 30, 2021 Three Months Ended June 30, 2020 RNF from external customers (a) Intersegment Total RNF RNF from external customers (a) Intersegment Total RNF Mid-Atlantic $ 567 $ 5 $ 572 $ 516 $ 9 $ 525 Midwest 658 — 658 702 1 703 New York 289 3 292 243 3 246 ERCOT 80 3 83 92 5 97 Other Power Regions 157 (21) 136 181 (24) 157 Total Revenues net of purchased power and fuel expense for Reportable Segments 1,751 (10) 1,741 1,734 (6) 1,728 Other (b) 455 10 465 204 6 210 Total Generation Revenues net of purchased power and fuel expense $ 2,206 $ — $ 2,206 $ 1,938 $ — $ 1,938 __________ (a) Includes purchases and sales from/to third parties and affiliated sales to the Utility Registrants. (b) Other represents activities not allocated to a region. See text above for a description of included activities. Includes unrealized mark-to-market gains of $314 million and gains of $85 million in 2021 and 2020, respectively and the elimination of intersegment RNF.
Schedule of Revenue by Major Customers by Reporting Segments [Table Text Block]	Electric and Gas Revenue by Customer Class (Utility Registrants): Three Months Ended June 30, 2021 Revenues from contracts with customers ComEd PECO BGE PHI Pepco DPL ACE Rate-regulated electric revenues Residential $ 759 $ 383 $ 299 $ 537 $ 223 $ 147 $ 167 Small commercial & industrial 377 99 60 124 32 46 46 Large commercial & industrial 138 59 108 257 188 22 47 Public authorities & electric railroads 11 8 7 17 10 3 4 Other (a) 214 54 87 139 50 46 43 Total rate-regulated electric revenues (b) $ 1,499 $ 603 $ 561 $ 1,074 $ 503 $ 264 $ 307 Rate-regulated natural gas revenues Residential $ — $ 55 $ 81 $ 12 $ — $ 12 $ — Small commercial & industrial — 22 13 6 — 6 — Large commercial & industrial — — 27 1 — 1 — Transportation — 5 — 3 — 3 — Other (c) — 1 6 2 — 2 — Total rate-regulated natural gas revenues (d) $ — $ 83 $ 127 $ 24 $ — $ 24 $ — Total rate-regulated revenues from contracts with customers $ 1,499 $ 686 $ 688 $ 1,098 $ 503 $ 288 $ 307 Other revenues Revenues from alternative revenue programs $ 9 $ 7 $ (10) $ 41 $ 19 $ 10 $ 12 Other rate-regulated electric revenues (e) 9 — 3 1 1 — — Other rate-regulated natural gas revenues (e) — — 1 — — — — Total other revenues $ 18 $ 7 $ (6) $ 42 $ 20 $ 10 $ 12 Total rate-regulated revenues for reportable segments $ 1,517 $ 693 $ 682 $ 1,140 $ 523 $ 298 $ 319 Three Months Ended June 30, 2020 Revenues from contracts with customers ComEd PECO BGE PHI Pepco DPL ACE Rate-regulated electric revenues Residential $ 767 $ 377 $ 304 $ 529 $ 237 $ 147 $ 145 Small commercial & industrial 327 88 51 105 29 39 37 Large commercial & industrial 119 55 94 240 175 22 43 Public authorities & electric railroads 11 7 7 15 8 3 4 Other (a) 218 55 76 161 58 51 53 Total rate-regulated electric revenues (b) $ 1,442 $ 582 $ 532 $ 1,050 $ 507 $ 262 $ 282 Rate-regulated natural gas revenues Residential $ — $ 70 $ 81 $ 17 $ — $ 17 $ — Small commercial & industrial — 19 12 8 — 8 — Large commercial & industrial — — 24 1 — 1 — Transportation — 6 — 3 — 3 — Other (c) — 1 3 1 — 1 — Total rate-regulated natural gas revenues (d) $ — $ 96 $ 120 $ 30 $ — $ 30 $ — Total rate-regulated revenues from contracts with customers $ 1,442 $ 678 $ 652 $ 1,080 $ 507 $ 292 $ 282 Other revenues Revenues from alternative revenue programs $ (25) $ 4 $ (37) $ (64) $ (13) $ (25) $ (26) Other rate-regulated electric revenues (e) — — 1 — — — — Other rate-regulated natural gas revenues (e) — (1) — — — — — Total other revenues $ (25) $ 3 $ (36) $ (64) $ (13) $ (25) $ (26) Total rate-regulated revenues for reportable segments $ 1,417 $ 681 $ 616 $ 1,016 $ 494 $ 267 $ 256 __________ (a) Includes revenues from transmission revenue from PJM, wholesale electric revenue and mutual assistance revenue. (b) Includes operating revenues from affiliates in 2021 and 2020 respectively of: • $5 million, $11 million at ComEd • $1 million, $1 million at PECO • $4 million, $3 million at BGE • $4 million, $3 million at PHI • $1 million, $1 million at Pepco • $2 million, $2 million at DPL • $1 million, $1 million at ACE (c) Includes revenues from off-system natural gas sales. (d) Includes operating revenues from affiliates in 2021 and 2020 respectively of: • less than $1 million at PECO both 2021 and 2020 • $3 million, $1 million at BGE (e) Includes late payment charge revenues.
Year to Date [Member]
Segment Tables [Line Items]
Analysis and reconciliation of reportable segment information	Six Months Ended June 30, 2021 and 2020 Generation ComEd PECO BGE PHI Other (a) Intersegment Exelon Operating revenues (b) : 2021 Competitive businesses electric revenues $ 7,935 $ — $ — $ — $ — $ — $ (546) $ 7,389 Generation ComEd PECO BGE PHI Other (a) Intersegment Exelon Competitive businesses natural gas revenues 1,833 — — — — — — 1,833 Competitive businesses other revenues (56) — — — — — (1) (57) Rate-regulated electric revenues — 3,052 1,271 1,190 2,283 — (21) 7,775 Rate-regulated natural gas revenues — — 311 466 95 — (7) 865 Shared service and other revenues — — — — 6 1,013 (1,019) — Total operating revenues $ 9,712 $ 3,052 $ 1,582 $ 1,656 $ 2,384 $ 1,013 $ (1,594) $ 17,805 2020 Competitive businesses electric revenues $ 7,165 $ — $ — $ — $ — $ — $ (594) $ 6,571 Competitive businesses natural gas revenues 1,025 — — — — — (3) 1,022 Competitive businesses other revenues 423 — — — — — (2) 421 Rate-regulated electric revenues — 2,856 1,189 1,118 2,086 — (27) 7,222 Rate-regulated natural gas revenues — — 304 436 94 — (2) 832 Shared service and other revenues — — — — 7 953 (959) 1 Total operating revenues $ 8,613 $ 2,856 $ 1,493 $ 1,554 $ 2,187 $ 953 $ (1,587) $ 16,069 Intersegment revenues (c) : 2021 $ 549 $ 11 $ 4 $ 13 $ 7 $ 1,010 $ (1,594) $ — 2020 601 16 4 10 7 949 (1,585) 2 Depreciation and amortization: 2021 $ 1,869 $ 589 $ 173 $ 293 $ 404 $ 35 $ — $ 3,363 2020 604 547 173 272 385 42 — 2,023 Operating expenses: 2021 $ 11,141 $ 2,406 $ 1,231 $ 1,372 $ 2,013 $ 1,029 $ (1,549) $ 17,643 2020 7,947 2,497 1,242 1,263 1,955 958 (1,564) 14,298 Interest expense, net: 2021 $ 148 $ 193 $ 80 $ 67 $ 134 $ 161 $ — $ 783 2020 197 192 71 64 134 179 — 837 Generation ComEd PECO BGE PHI Other (a) Intersegment Exelon Income (loss) before income taxes: 2021 $ (823) $ 475 $ 283 $ 233 $ 273 $ (174) $ 1 $ 268 2020 313 189 187 237 126 (175) 2 879 Income Taxes: 2021 $ (70) $ 85 $ 12 $ (21) $ 5 $ 44 $ — $ 55 2020 (59) 82 9 18 (76) (49) — (75) Net income (loss): 2021 $ (756) $ 390 $ 271 $ 254 $ 269 $ (218) $ 1 $ 211 2020 368 107 178 219 202 (126) 2 950 Capital Expenditures: 2021 $ 719 $ 1,162 $ 577 $ 620 $ 889 $ 73 $ — $ 4,040 2020 930 1,029 512 548 686 68 — 3,773 Total assets: June 30, 2021 $ 45,821 $ 35,324 $ 13,491 $ 12,186 $ 24,235 $ 8,507 $ (10,168) $ 129,396 December 31, 2020 48,094 34,466 12,531 11,650 23,736 9,005 (10,165) 129,317 __________ (a) Other primarily includes Exelon’s corporate operations, shared service entities, and other financing and investment activities. (b) Includes gross utility tax receipts from customers. The offsetting remittance of utility taxes to the governing bodies is recorded in expenses in the Registrants’ Consolidated Statements of Operations and Comprehensive Income. See Note 18 — Supplemental Financial Information for additional information on total utility taxes. (c) Intersegment revenues exclude sales to unconsolidated affiliates. The intersegment profit associated with Generation’s sale of certain products and services by and between Exelon’s segments is not eliminated in consolidation due to the recognition of intersegment profit in accordance with regulatory accounting guidance. For Exelon, these amounts are included in Operating revenues in the Consolidated Statements of Operations and Comprehensive Income. See Note 19 — Related Party Transactions for additional information on intersegment revenues. PHI: Pepco DPL ACE Other (a) Intersegment PHI Operating revenues (b) : 2021 Rate-regulated electric revenues $ 1,076 $ 585 $ 629 $ — $ (7) $ 2,283 Rate-regulated natural gas revenues — 95 — — — 95 Shared service and other revenues — — — 189 (183) 6 Total operating revenues $ 1,076 $ 680 $ 629 $ 189 $ (190) $ 2,384 2020 Rate-regulated electric revenues $ 1,039 $ 523 $ 532 $ — $ (8) $ 2,086 Rate-regulated natural gas revenues — 94 — — — 94 Shared service and other revenues — — — 189 (182) 7 Total operating revenues $ 1,039 $ 617 $ 532 $ 189 $ (190) $ 2,187 Intersegment revenues (c) : 2021 $ 3 $ 4 $ 1 $ 189 $ (190) $ 7 2020 3 4 1 189 (190) 7 Depreciation and amortization: 2021 $ 199 $ 104 $ 87 $ 14 $ — $ 404 2020 186 94 86 19 — 385 Operating expenses: 2021 $ 895 $ 564 $ 552 $ 192 $ (190) $ 2,013 2020 899 547 509 190 (190) 1,955 Interest expense, net: 2021 $ 69 $ 30 $ 29 $ 6 $ — $ 134 2020 68 31 29 6 — 134 Income (loss) before income taxes: 2021 $ 137 $ 92 $ 50 $ (6) $ — $ 273 2020 90 44 (1) (7) — 126 Income Taxes: 2021 $ 3 $ 6 $ (1) $ (3) $ — $ 5 2020 (19) (20) (32) (5) — (76) Net income (loss): 2021 $ 134 $ 86 $ 51 $ (2) $ — $ 269 2020 109 64 31 (2) — 202 Capital Expenditures: 2021 $ 439 $ 211 $ 239 $ — $ — $ 889 2020 324 184 178 — — 686 Total assets: June 30, 2021 $ 9,588 $ 5,229 $ 4,473 $ 5,014 $ (69) $ 24,235 December 31, 2020 9,264 5,140 4,286 5,079 (33) 23,736 __________ (a) Other primarily includes PHI’s corporate operations, shared service entities, and other financing and investment activities. (b) Includes gross utility tax receipts from customers. The offsetting remittance of utility taxes to the governing bodies is recorded in expenses in the Registrants’ Consolidated Statements of Operations and Comprehensive Income. See Note 18 — Supplemental Financial Information for additional information on total utility taxes. (c) Includes intersegment revenues with ComEd, BGE, and PECO, which are eliminated at Exelon.
Analysis and reconciliation of reportable segment revenues for Generation	The following tables disaggregate the Registrants' revenue recognized from contracts with customers into categories that depict how the nature, amount, timing, and uncertainty of revenue and cash flows are affected by economic factors. For Generation, the disaggregation of revenues reflects Generation’s two primary products of power sales and natural gas sales, with further disaggregation of power sales provided by geographic region. For the Utility Registrants, the disaggregation of revenues reflects the two primary utility services of rate-regulated electric sales and rate-regulated natural gas sales (where applicable), with further disaggregation of these tariff sales provided by major customer groups. Exelon’s disaggregated revenues are consistent with Generation and the Utility Registrants, but exclude any intercompany revenues. Competitive Business Revenues (Generation): Six Months Ended June 30, 2021 Revenues from external customers (a) Intersegment Total Contracts with customers Other (b) Total Mid-Atlantic $ 2,233 $ 11 $ 2,244 $ 11 $ 2,255 Midwest 1,983 (24) 1,959 1 1,960 New York 759 (40) 719 — 719 ERCOT 533 (10) 523 9 532 Other Power Regions 2,095 395 2,490 (21) 2,469 Total Competitive Businesses Electric Revenues 7,603 332 7,935 — 7,935 Competitive Businesses Natural Gas Revenues 1,117 716 1,833 — 1,833 Competitive Businesses Other Revenues (c) 195 (251) (56) — (56) Total Generation Consolidated Operating Revenues $ 8,915 $ 797 $ 9,712 $ — $ 9,712 Six Months Ended June 30, 2020 Revenues from external customers (a) Intersegment Total Contracts with customers Other (b) Total Mid-Atlantic $ 2,365 $ (133) $ 2,232 $ 15 $ 2,247 Midwest 1,798 172 1,970 (6) 1,964 New York 672 (16) 656 (1) 655 ERCOT 330 81 411 13 424 Other Power Regions 1,782 114 1,896 (21) 1,875 Total Competitive Businesses Electric Revenues 6,947 218 7,165 — 7,165 Competitive Businesses Natural Gas Revenues 712 313 1,025 — 1,025 Competitive Businesses Other Revenues (c) 185 238 423 — 423 Total Generation Consolidated Operating Revenues $ 7,844 $ 769 $ 8,613 $ — $ 8,613 __________ (a) Includes all wholesale and retail electric sales to third parties and affiliated sales to the Utility Registrants. (b) Includes revenues from derivatives and leases. (c) Other represents activities not allocated to a region. See text above for a description of included activities. Includes unrealized mark-to-market losses of $323 million and gains of $200 million in 2021 and 2020, respectively, and elimination of intersegment revenues. Revenues net of purchased power and fuel expense (Generation): Six Months Ended June 30, 2021 Six Months Ended June 30, 2020 RNF from external customers (a) Intersegment Total RNF RNF from external customers (a) Intersegment Total RNF Mid-Atlantic $ 1,130 $ 11 $ 1,141 $ 1,074 $ 18 $ 1,092 Midwest 1,359 1 1,360 1,431 (4) 1,427 New York 531 5 536 433 7 440 ERCOT (957) (145) (1,102) 168 9 177 Other Power Regions 409 (56) 353 355 (43) 312 Total Revenues net of purchased power and fuel expense for Reportable Segments 2,472 (184) 2,288 3,461 (13) 3,448 Other (b) 683 184 867 506 13 519 Total Generation Revenues net of purchased power and fuel expense $ 3,155 $ — $ 3,155 $ 3,967 $ — $ 3,967 __________ (a) Includes purchases and sales from/to third parties and affiliated sales to the Utility Registrants. (b) Other represents activities not allocated to a region. See text above for a description of included activities. Primarily includes: • unrealized mark-to-market gains of $489 million and gains of $218 million in 2021 and 2020, respectively; • accelerated nuclear fuel amortization associated with announced early plant retirements as discussed in Note 7 - Early Plant Retirements of $106 million in 2021; and • the elimination of intersegment RNF.
Schedule of Revenue by Major Customers by Reporting Segments [Table Text Block]	Electric and Gas Revenue by Customer Class (Utility Registrants): Six Months Ended June 30, 2021 Revenues from contracts with customers ComEd PECO BGE PHI Pepco DPL ACE Rate-regulated electric revenues Residential $ 1,502 $ 816 $ 662 $ 1,142 $ 476 $ 337 $ 329 Small commercial & industrial 744 199 129 242 65 92 85 Large commercial & industrial 271 116 213 505 372 43 90 Public authorities & electric railroads 22 17 13 30 16 7 7 Other (a) 433 106 165 283 101 87 95 Total rate-regulated electric revenues (b) $ 2,972 $ 1,254 $ 1,182 $ 2,202 $ 1,030 $ 566 $ 606 Rate-regulated natural gas revenues Residential $ — $ 215 $ 297 $ 57 $ — $ 57 $ — Small commercial & industrial — 81 48 24 — 24 — Large commercial & industrial — — 81 3 — 3 — Transportation — 12 — 8 — 8 — Other (c) — 3 36 2 — 3 — Total rate-regulated natural gas revenues (d) $ — $ 311 $ 462 $ 94 $ — $ 95 $ — Total rate-regulated revenues from contracts with customers $ 2,972 $ 1,565 $ 1,644 $ 2,296 $ 1,030 $ 661 $ 606 Other revenues Revenues from alternative revenue programs $ 64 $ 17 $ 8 $ 88 $ 46 $ 19 $ 23 Other rate-regulated electric revenues (e) 16 — 3 — — — — Other rate-regulated natural gas revenues (e) — — 1 — — — — Total other revenues $ 80 $ 17 $ 12 $ 88 $ 46 $ 19 $ 23 Total rate-regulated revenues for reportable segments $ 3,052 $ 1,582 $ 1,656 $ 2,384 $ 1,076 $ 680 $ 629 Six Months Ended June 30, 2020 Revenues from contracts with customers ComEd PECO BGE PHI Pepco DPL ACE Rate-regulated electric revenues Residential $ 1,468 $ 759 $ 644 $ 1,062 $ 472 $ 308 $ 282 Small commercial & industrial 689 187 118 221 65 82 74 Large commercial & industrial 253 108 198 493 363 45 85 Public authorities & electric railroads 23 14 14 30 17 6 7 Other (a) 430 113 154 333 119 105 109 Total rate-regulated electric revenues (b) $ 2,863 $ 1,181 $ 1,128 $ 2,139 $ 1,036 $ 546 $ 557 Rate-regulated natural gas revenues Residential $ — $ 220 $ 287 $ 57 $ — $ 57 $ — Small commercial & industrial — 70 46 25 — 25 — Large commercial & industrial — — 76 2 — 2 — Transportation — 12 — 7 — 7 — Other (c) — 2 13 3 — 3 — Total rate-regulated natural gas revenues (d) $ — $ 304 $ 422 $ 94 $ — $ 94 $ — Total rate-regulated revenues from contracts with customers $ 2,863 $ 1,485 $ 1,550 $ 2,233 $ 1,036 $ 640 $ 557 Other revenues Revenues from alternative revenue programs $ (13) $ 5 $ — $ (47) $ 2 $ (24) $ (25) Other rate-regulated electric revenues (e) 6 3 3 1 1 1 — Other rate-regulated natural gas revenues (e) — — 1 — — — — Total other revenues $ (7) $ 8 $ 4 $ (46) $ 3 $ (23) $ (25) Total rate-regulated revenues for reportable segments $ 2,856 $ 1,493 $ 1,554 $ 2,187 $ 1,039 $ 617 $ 532 __________ (a) Includes revenues from transmission revenue from PJM, wholesale electric revenue and mutual assistance revenue. (b) Includes operating revenues from affiliates in 2021 and 2020 respectively of: • $11 million, $16 million at ComEd • $3 million, $3 million at PECO • $5 million, $6 million at BGE • $7 million, $7 million at PHI • $3 million, $3 million at Pepco • $4 million, $4 million at DPL • $1 million, $1 million at ACE (c) Includes revenues from off-system natural gas sales. (d) Includes operating revenues from affiliates in 2021 and 2020 respectively of: • $1 million, less than $1 million at PECO • $7 million, $4 million at BGE (e) Includes late payment charge revenues.

Accounts Receivable (Tables)

Accounts Receivable (Tables)	6 Months Ended
Accounts Receivable (Tables)	Jun. 30, 2021
Accounts, Notes, Loans and Financing Receivable, Gross, Allowance, and Net [Abstract]
Allowance for credit loss rollforward	The following tables present the rollforward of Allowance for Credit Losses on Customer Accounts Receivable. Three Months Ended June 30, 2021 Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE Balance as of March 31, 2021 $ 442 $ 65 $ 103 $ 130 $ 43 $ 101 $ 41 $ 25 $ 35 Plus: Current period provision for expected credit losses (29) 13 (9) (14) (14) (5) (1) (5) 1 Less: Write-offs, net of recoveries (a) 18 3 5 5 2 3 2 1 — Balance as of June 30, 2021 $ 395 $ 75 $ 89 $ 111 $ 27 $ 93 $ 38 $ 19 $ 36 Three Months Ended June 30, 2020 Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE Balance as of March 31, 2020 $ 278 $ 81 $ 71 $ 66 $ 18 $ 42 $ 15 $ 13 $ 14 Plus: Current period provision for expected credit losses 51 9 7 10 6 19 8 5 6 Less: Write-offs, net of recoveries (a) 12 1 6 5 1 (1) (1) — — Less: Sale of customer accounts receivable (b) 56 56 — — — — — — — Balance as of June 30, 2020 $ 261 $ 33 $ 72 $ 71 $ 23 $ 62 $ 24 $ 18 $ 20 Six Months Ended June 30, 2021 Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE Balance as of December 31, 2020 $ 366 $ 32 $ 97 $ 116 $ 35 $ 86 $ 32 $ 22 $ 32 Plus: Current period provision for expected credit losses (c) 75 47 12 6 (5) 15 10 1 4 Less: Write-offs, net of recoveries (a) 46 4 20 11 3 8 4 4 — Balance as of June 30, 2021 $ 395 $ 75 $ 89 $ 111 $ 27 $ 93 $ 38 $ 19 $ 36 Six Months Ended June 30, 2020 Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE Balance as of December 31, 2019 $ 243 $ 80 $ 59 $ 55 $ 12 $ 37 $ 13 $ 11 $ 13 Plus: Current period provision for expected credit losses 106 13 25 28 14 26 11 7 8 Less: Write-offs, net of recoveries (a) 32 4 12 12 3 1 — — 1 Less: Sale of customer accounts receivable (b) 56 56 — — — — — — — Balance as of June 30, 2020 $ 261 $ 33 $ 72 $ 71 $ 23 $ 62 $ 24 $ 18 $ 20 __________ (a) Recoveries were not material to the Registrants. (b) See below for additional information on the sale of customer accounts receivable at Generation in the second quarter of 2020. (c) For Generation, primarily relates to the impacts of the February 2021 extreme cold weather event. See Note 3 — Regulatory Matters for additional information. The following tables present the rollforward of Allowance for Credit Losses on Other Accounts Receivable. Three Months Ended June 30, 2021 Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE Balance as of March 31, 2021 $ 79 $ — $ 22 $ 11 $ 9 $ 37 $ 15 $ 10 $ 12 Plus: Current period provision for expected credit losses (4) 1 (3) (3) — 1 1 (1) 1 Less: Write-offs, net of recoveries (a) 3 — 1 1 1 — — — — Balance as of June 30, 2021 $ 72 $ 1 $ 18 $ 7 $ 8 $ 38 $ 16 $ 9 $ 13 Three Months Ended June 30, 2020 Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE Balance as of March 31, 2020 $ 52 $ — $ 22 $ 7 $ 5 $ 18 $ 8 $ 4 $ 6 Plus: Current period provision for expected credit losses 12 — 1 1 2 8 3 3 2 Less: Write-offs, net of recoveries (a) 3 — 1 1 1 — — — — Balance as of June 30, 2020 $ 61 $ — $ 22 $ 7 $ 6 $ 26 $ 11 $ 7 $ 8 Six Months Ended June 30, 2021 Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE Balance as of December 31, 2020 $ 71 $ — $ 21 $ 8 $ 9 $ 33 $ 13 $ 9 $ 11 Plus: Current period provision for expected credit losses 6 1 (2) 1 1 5 3 — 2 Less: Write-offs, net of recoveries (a) 5 — 1 2 2 — — — — Balance as of June 30, 2021 $ 72 $ 1 $ 18 $ 7 $ 8 $ 38 $ 16 $ 9 $ 13 Six Months Ended June 30, 2020 Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE Balance as of December 31, 2019 $ 48 $ — $ 20 $ 7 $ 5 $ 16 $ 7 $ 4 $ 5 Plus: Current period provision for expected credit losses 20 — 4 2 4 10 4 3 3 Less: Write-offs, net of recoveries (a) 7 — 2 2 3 — — — — Balance as of June 30, 2020 $ 61 $ — $ 22 $ 7 $ 6 $ 26 $ 11 $ 7 $ 8 __________ (a) Recoveries were not material to the Registrants.
Unbilled customer revenue	The following table provides additional information about unbilled customer revenues recorded in the Registrants' Consolidated Balance Sheets as of June 30, 2021 and December 31, 2020. Unbilled customer revenues (a) Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE June 30, 2021 $ 1,029 $ 329 $ 263 $ 131 $ 119 $ 187 $ 90 $ 39 $ 58 December 31, 2020 998 258 218 147 197 178 87 62 29 __________ (a) Unbilled customer revenues are classified in Customer accounts receivables, net in the Registrants' Consolidated Balance Sheets.
Purchases and sales of accounts receivable	The following table summarizes the impact of the sale of certain receivables: June 30, 2021 December 31, 2020 Derecognized receivables transferred at fair value $ 1,274 $ 1,139 Cash proceeds received 900 500 DPP 374 639 Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 Loss on sale of receivables (a) $ 8 $ 15 $ 25 $ 15 __________ (a) Reflected in Operating and maintenance expense on Exelon's and Generation's Consolidated Statements of Operations and Comprehensive Income. Six Months Ended June 30, 2021 2020 Proceeds from new transfers (a) $ 2,689 $ 927 Cash collections received on DPP and reinvested in the Facility (b) 1,809 1,102 Cash collections reinvested in the Facility 4,498 2,029 __________ (a) Customer accounts receivable sold into the Facility were $4,647 million and $2,032 million for the six months ended June 30, 2021 and June 30, 2020, respectively (b) Does not include the $400 million in cash proceeds received from the Purchasers in the first quarter of 2021. Generation is required, under supplier tariffs in ISO-NE, MISO, NYISO, and PJM, to sell customer and other receivables to utility companies, which include the Utility Registrants. The Utility Registrants are required, under separate legislation and regulations in Illinois, Pennsylvania, Maryland, District of Columbia, Delaware, and New Jersey, to purchase certain receivables from alternative retail electric and, as applicable, natural gas suppliers that participate in the utilities' consolidated billing. The following tables present the total receivables purchased and sold. Six Months Ended June 30, 2021 Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE Total receivables purchased $ 1,823 $ — $ 485 $ 507 $ 343 $ 503 $ 310 $ 103 $ 90 Total receivables sold 92 107 — — — — — — — Related party transactions: Receivables purchased from Generation — — — — 15 — — — — Receivables sold to the Utility Registrants — 15 — — — — — — — Six Months Ended June 30, 2020 Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE Total receivables purchased $ 1,584 $ — $ 518 $ 494 $ 333 $ 485 $ 303 $ 98 $ 84 Total receivables sold 533 779 — — — — — — — Related party transactions: Receivables purchased from Generation — — 34 67 73 72 51 13 8 Receivables sold to the Utility Registrants — 246 — — — — — — —

Early Plant Retirements (Tables

Early Plant Retirements (Tables)	6 Months Ended
Early Plant Retirements (Tables)	Jun. 30, 2021
Property, Plant and Equipment [Abstract]
Restructuring and Related Costs [Table Text Block]	As a result of the decision to early retire Byron and Dresden, Exelon and Generation recognized certain one-time charges in the third and fourth quarters of 2020 related to materials and supplies inventory reserve adjustments, employee-related costs including severance benefit costs further discussed below, and construction work-in-progress impairments, among other items. In addition, as a result of the decisions to early retire Byron and Dresden, there are ongoing annual financial impacts stemming from shortening the expected economic useful lives of these nuclear plants primarily related to accelerated depreciation of plant assets (including any ARC), accelerated amortization of nuclear fuel, and changes in ARO accretion expense associated with the changes in decommissioning timing and cost assumptions to reflect an earlier retirement date. The total impact for the three and six months ended June 30, 2021 on Exelon's and Generation's Consolidated Statements of Operations and Comprehensive Income is summarized in the table below. Income statement expense (pre-tax) Three Months Ended June 30, 2021 (a) Six Months Ended June 30, 2021 (a) Depreciation and amortization Accelerated depreciation (a) $ 611 $ 1,230 Accelerated nuclear fuel amortization 52 106 Operating and maintenance Other charges 2 4 Contractual offset (b) (166) (391) Total $ 499 $ 949 _________ (a) Includes the accelerated depreciation of plant assets including any ARC. (b) Reflects contractual offset for ARO accretion and ARC depreciation and excludes any changes in earnings in the NDT funds. Decommissioning-related impacts were not offset for the Byron units starting in the second quarter of 2021 due to the inability to recognize a regulatory asset at ComEd. Based on the regulatory agreement with the ICC, decommissioning-related activities are offset within Exelon's and Generation's Consolidated Statements of Operations and Comprehensive Income as long as the net cumulative decommissioning-related activities result in a regulatory liability at ComEd. The offset resulted in an equal adjustment to the noncurrent payables to ComEd at Generation and an adjustment to the regulatory liabilities at ComEd. See Note 8 - Nuclear Decommissioning for additional information.
Implications of Potential Early Plant Retirement on Balance Sheet [Table Text Block]	The following table provides the balance sheet amounts as of June 30, 2021 for Exelon's and Generation's significant assets and liabilities associated with the Braidwood and LaSalle nuclear plants. Current depreciation provisions are based on the estimated useful lives of these nuclear generating stations, which reflect the first renewal of the operating licenses. Braidwood LaSalle Total Asset Balances Materials and supplies inventory, net $ 82 $ 105 $ 187 Nuclear fuel inventory, net 196 244 440 Completed plant, net 1,380 1,610 2,990 Construction work in progress 30 12 42 Liability Balances Asset retirement obligation (585) (975) (1,560) NRC License First Renewal Term 2046 (Unit 1) 2042 (Unit 1) 2047 (Unit 2) 2043 (Unit 2)

Nuclear Decommissioning (Tables

Nuclear Decommissioning (Tables)	6 Months Ended
Nuclear Decommissioning (Tables)	Jun. 30, 2021
Schedule Of Nuclear Decommissioning [Line Items]
Schedule of Change in Asset Retirement Obligation [Table Text Block]	The following table provides a rollforward of the nuclear decommissioning ARO reflected in Exelon’s and Generation’s Consolidated Balance Sheets from December 31, 2020 to June 30, 2021: Nuclear decommissioning ARO at December 31, 2020 (a) $ 11,922 Accretion expense 249 Costs incurred related to decommissioning plants (39) Nuclear decommissioning ARO at June 30, 2021 (a) $ 12,132 _________ (a) Includes $84 million and $80 million as the current portion of the ARO at June 30, 2021 and December 31, 2020, which is included in Other current liabilities in Exelon’s and Generation’s Consolidated Balance Sheets.

Income Taxes (Tables)

Income Taxes (Tables)	6 Months Ended
Income Taxes (Tables)	Jun. 30, 2021
Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items]
Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]	The effective income tax rate from continuing operations varies from the U.S. federal statutory rate principally due to the following: Three Months Ended June 30, 2021 Exelon (a) Generation (a) ComEd (a) PECO (a) BGE (a) (b) PHI (a) Pepco (a) DPL (a) ACE (a) U.S. Federal statutory rate 21.0% 21.0% 21.0% 21.0% 21.0% 21.0% 21.0% 21.0% 21.0% Increase (decrease) due to: State income taxes, net of Federal income tax benefit 1.4 (1.3) 8.0 (2.9) (12.5) 2.4 (2.1) 7.0 8.1 Qualified NDT fund income 17.9 85.2 — — — — — — — Amortization of investment tax credit, including deferred taxes on basis difference — (1.8) (0.1) — (0.1) (0.1) — (0.2) (0.2) Plant basis differences (3.1) — (0.7) (12.5) (2.3) (1.1) (1.5) (0.7) (0.6) Production tax credits and other credits (1.9) (13.0) (0.8) — (3.6) (0.8) (0.7) (0.9) (0.6) Noncontrolling interests (0.9) (4.2) — — — — — — — Excess deferred tax amortization (10.4) — (7.0) (3.3) (17.5) (22.3) (19.0) (21.9) (28.2) Other (10.6) 2.8 (1.1) (0.4) (6.6) (1.3) (1.9) (1.1) (2.3) Effective income tax rate 13.4% 88.7% 19.3% 1.9% (21.6)% (2.2)% (4.2)% 3.2% (2.8)% Three Months Ended June 30, 2020 Exelon (a) Generation (a) ComEd (c) PECO (d) BGE (d) PHI (d) Pepco (d) DPL (e) ACE (e) U.S. Federal statutory rate 21.0% 21.0% 21.0% 21.0% 21.0% 21.0% 21.0% 21.0% 21.0% Increase (decrease) due to: State income taxes, net of Federal income tax benefit 3.8 3.1 (131.7) (9.7) 3.8 (25.8) 2.1 6.7 7.2 Qualified NDT fund income 18.8 17.3 — — — — — — — Deferred Prosecution Agreement payments 5.3 — (288.3) — — — — — — Amortization of investment tax credit, including deferred taxes on basis difference (0.6) (0.5) 2.9 — (0.2) (2.2) (0.1) 0.5 0.3 Plant basis differences (1.6) — 2.4 (23.6) (13.4) (44.7) (3.9) (1.1) 10.0 Production tax credits and other credits (1.4) (1.2) 3.3 — (1.0) (0.7) (0.1) 0.1 — Noncontrolling interests 0.1 0.1 — — — — — — — Excess deferred tax amortization (15.5) — 116.0 (4.8) (137.9) (1,358.5) (89.0) 284.0 174.5 Tax Settlements (1.9) (1.8) — — — — — — — Other (f) (0.4) 0.3 (32.3) (4.8) (1.7) 168.0 (2.7) (0.1) 7.0 Effective income tax rate 27.6% 38.3% (306.7)% (21.9)% (129.4)% (1,242.9)% (72.7)% 311.1% 220.0% __________ (a) Positive percentages represent income tax expense. Negative percentages represent income tax benefit. (b) For BGE, the income tax benefit is primarily due to the Maryland multi-year plan which resulted in the acceleration of certain income tax benefits. (c) ComEd recognized a loss before income taxes for the three months ended June 30, 2020. As a result, negative percentages represent income tax expense. The higher effective tax rate is primarily related to the nondeductible Deferred Prosecution Agreement payments. (d) At PECO, BGE, PHI, and Pepco, negative percentages represent an income tax benefit. At PECO, the lower effective tax rate is primarily related to an increase in plant basis differences attributable to storm repairs. At BGE, PHI, and Pepco, the lower effective tax rate is primarily attributable to accelerated amortization of transmission related deferred income tax regulatory liabilities as a result of regulatory settlements. (e) DPL and ACE recognized a loss before income taxes for the three months ended June 30, 2020. As a result, positive percentages represent an income tax benefit. At DPL and ACE, the higher effective tax rate is primarily attributable to accelerated amortization of transmission related deferred income tax regulatory liabilities as a result of regulatory settlements. (f) For Exelon, "Other" is primarily driven by the reversal of the consolidating income tax adjustment recorded at Exelon Corporate in the first quarter of 2021 that was required pursuant to GAAP interim reporting guidance. Six Months Ended June 30, 2021 Exelon (a) Generation (b) ComEd (a) PECO (a)(d) BGE (a)(c) PHI (a) Pepco (a) DPL (a) ACE (a) U.S. Federal statutory rate 21.0% 21.0% 21.0% 21.0% 21.0% 21.0% 21.0% 21.0% 21.0% Increase (decrease) due to: State income taxes, net of Federal income tax benefit (12.6) 5.3 7.4 (2.1) (10.5) 4.2 1.5 6.6 7.8 Qualified NDT fund income 56.2 (18.3) — — — — — — — Amortization of investment tax credit, including deferred taxes on basis difference (2.5) 0.7 (0.1) — (0.1) (0.1) — (0.2) (0.2) Plant basis differences (15.7) — (0.6) (11.3) (1.6) (1.3) (1.8) (0.7) (0.7) Production tax credits and other credits (11.0) 2.9 (0.5) — (0.9) (0.5) (0.5) (0.4) (0.5) Noncontrolling interests (2.5) 0.8 — — — — — — — Excess deferred tax amortization (50.9) — (7.0) (3.3) (15.9) (20.8) (17.2) (19.7) (28.3) Other (e) 38.5 (3.9) (2.3) (0.1) (1.0) (0.7) (0.8) (0.1) (1.1) Effective income tax rate 20.5% 8.5% 17.9% 4.2% (9.0)% 1.8% 2.2% 6.5% (2.0)% Six Months Ended June 30, 2020 Exelon (a) Generation (a) ComEd (a)(g) PECO (a)(d) BGE (a)(h) PHI (a)(h) Pepco (a)(h) DPL (a)(h) ACE (i) U.S. Federal statutory rate 21.0% 21.0% 21.0% 21.0% 21.0% 21.0% 21.0% 21.0% 21.0% Increase (decrease) due to: State income taxes, net of Federal income tax benefit 6.7 7.2 19.1 (1.6) 5.6 4.3 3.7 6.5 12.4 Qualified NDT fund income (5.7) (16.0) — — — — — — — Deferred Prosecution Agreement payments 4.8 — 22.2 — — — — — — Amortization of investment tax credit, including deferred taxes on basis difference (1.0) (2.3) (0.4) — (0.1) (0.2) (0.1) (0.3) 7.2 Plant basis differences (3.7) — (1.4) (11.0) (2.0) (3.5) (2.7) (0.6) 146.2 Production tax credits and other credits (2.2) (5.5) (0.4) — (0.2) (0.1) (0.1) — 0.7 Noncontrolling interests 1.1 3.2 — — — — — — — Excess deferred tax amortization (20.9) — (20.2) (3.3) (16.1) (80.3) (41.6) (72.9) 2,613.8 Tax Settlements (f) (9.3) (26.1) — — — — — — — Other 0.7 (0.3) 3.5 (0.3) (0.6) (1.5) (1.3) 0.8 398.7 Effective income tax rate (8.5)% (18.8)% 43.4% 4.8% 7.6% (60.3)% (21.1)% (45.5)% 3,200.0% __________ (a) Positive percentages represent income tax expense. Negative percentages represent income tax benefit. (b) Generation recognized a loss before income taxes for the six months ended June 30, 2021. As a result, positive percentages represent an income tax benefit for the period presented. (c) For BGE, the income tax benefit is primarily due to the Maryland multi-year plan which resulted in the acceleration of certain income tax benefits. (d) For PECO, the lower effective tax rate is primarily attributable to plant basis differences attributable to tax repairs. (e) For Exelon, "Other" is primarily driven by the consolidating income tax adjustment recorded at Exelon Corporate in the first quarter of 2021 that was required pursuant to GAAP interim reporting guidance. This incremental expense will reverse by year-end and will not have an impact on annual results. (f) Exelon's and Generation’s unrecognized federal and state tax benefits decreased in the first quarter of 2020 by approximately $411 million due to the settlement of a federal refund claim with IRS Appeals. The recognition of these tax benefits resulted in an increase to Exelon's and Generation’s net income of $76 million and $73 million, respectively, in the first quarter of 2020, reflecting a decrease to Exelon's and Generation's income tax expense of $67 million. (g) At ComEd, the higher effective tax rate is primarily related to the nondeductible Deferred Prosecution Agreement payments. (h) At BGE, PHI, Pepco, and DPL, the lower effective tax rate is primarily attributable to accelerated amortization of transmission related deferred income tax regulatory liabilities as a result of regulatory settlements. (i) ACE recognized a loss before income taxes for the six months ended June 30, 2020. As a result, a positive percentage at ACE represents an income tax benefit for the period presented. At ACE, the higher effective tax rate is primarily attributable to accelerated amortization of transmission related deferred income tax regulatory liabilities as a result of regulatory settlements.
Schedule of Unrecognized Tax Benefits Roll Forward [Table Text Block]	PHI and ACE have the following unrecognized tax benefits as of June 30, 2021 and December 31, 2020. Exelon's, Generation's, ComEd's, PECO's, BGE's, Pepco's, and DPL's amounts are not material. PHI ACE June 30, 2021 $ 54 $ 16 December 31, 2020 52 15

Retirement Benefits (Tables)

Retirement Benefits (Tables)	6 Months Ended
Retirement Benefits (Tables)	Jun. 30, 2021
Retirement Benefits [Abstract]
Calculation of Net Periodic Benefit Costs	A portion of the net periodic benefit cost for all plans is capitalized within the Consolidated Balance Sheets. The following table presents the components of Exelon's net periodic benefit costs, prior to capitalization, for the three and six months ended June 30, 2021 and 2020. Pension Benefits OPEB Three Months Ended June 30, Three Months Ended June 30, 2021 2020 2021 2020 Components of net periodic benefit cost: Service cost $ 111 $ 96 $ 20 $ 22 Interest cost 160 190 28 39 Expected return on assets (333) (318) (39) (40) Amortization of: Prior service cost (credit) — 1 (9) (31) Actuarial loss 149 128 10 12 Settlement charges 4 6 — — Net periodic benefit cost $ 91 $ 103 $ 10 $ 2 Pension Benefits OPEB Six Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 Components of net periodic benefit cost: Service cost $ 220 $ 193 $ 40 $ 45 Interest cost 320 379 57 77 Expected return on assets (667) (636) (79) (81) Amortization of: Prior service cost (credit) 1 2 (17) (62) Actuarial loss 299 256 19 24 Curtailment benefits — — (1) — Settlement charges 4 6 — — Net periodic benefit cost $ 177 $ 200 $ 19 $ 3
Allocated Portion of Pension and Postretirement Benefit Costs	The amounts below represent the Registrants' allocated pension and OPEB costs. For Exelon, the service cost component is included in Operating and maintenance expense and Property, plant, and equipment, net while the non-service cost components are included in Other, net and Regulatory assets. For Generation and the Utility Registrants, the service cost and non-service cost components are included in Operating and maintenance expense and Property, plant, and equipment, net in their consolidated financial statements. Three Months Ended June 30, Six Months Ended June 30, Pension and OPEB Costs 2021 2020 2021 2020 Exelon $ 101 $ 105 $ 196 $ 203 Generation 30 32 56 59 ComEd 32 28 64 57 PECO 2 1 4 3 BGE 16 16 31 31 PHI 12 18 24 35 Pepco 2 4 3 7 DPL 1 2 1 4 ACE 3 3 5 7
Defined Contribution Savings Plans	The Registrants participate in various 401(k) defined contribution savings plans that are sponsored by Exelon. The plans are qualified under applicable sections of the IRC and allow employees to contribute a portion of their pre-tax and/or after-tax income in accordance with specified guidelines. All Registrants match a percentage of the employee contributions up to certain limits. The following table presents the matching contributions to the savings plans for the three and six months ended June 30, 2021 and 2020, respectively. Three Months Ended June 30, Six Months Ended June 30, Savings Plans Matching Contributions 2021 2020 2021 2020 Exelon $ 36 $ 34 $ 69 $ 67 Generation 13 14 26 27 ComEd 10 9 18 16 PECO 3 2 6 5 BGE 2 2 4 4 PHI 4 3 7 6 Pepco 1 1 2 2 DPL 1 — 2 1 ACE 1 1 1 1

Derivative Financial Instrume_2

Derivative Financial Instruments (Tables)	6 Months Ended
Derivative Financial Instruments (Tables)	Jun. 30, 2021
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Summary of the derivative fair value	The following table provides a summary of the derivative fair value balances recorded by Exelon, Generation, and ComEd as of June 30, 2021 and December 31, 2020: Exelon Generation ComEd June 30, 2021 Total Economic Proprietary Collateral (a)(b) Netting (a) Subtotal Economic Mark-to-market derivative assets $ 748 $ 6,541 $ 64 $ (241) $ (5,616) $ 748 $ — Mark-to-market derivative assets 438 1,997 10 (92) (1,477) 438 — Total mark-to-market derivative assets 1,186 8,538 74 (333) (7,093) 1,186 — Mark-to-market derivative liabilities (713) (6,075) (54) (177) 5,616 (690) (23) Mark-to-market derivative liabilities (553) (1,739) (7) (42) 1,477 (311) (242) Total mark-to-market derivative liabilities (1,266) (7,814) (61) (219) 7,093 (1,001) (265) Total mark-to-market derivative net assets (liabilities) $ (80) $ 724 $ 13 $ (552) $ — $ 185 $ (265) Exelon Generation ComEd December 31, 2020 Total Economic Proprietary Collateral (a)(b) Netting (a) Subtotal Economic Mark-to-market derivative assets $ 639 $ 2,757 $ 40 $ 103 $ (2,261) $ 639 $ — Mark-to-market derivative assets 554 1,501 4 64 (1,015) 554 — Total mark-to-market derivative assets 1,193 4,258 44 167 (3,276) 1,193 — Mark-to-market derivative liabilities (293) (2,629) (23) 131 2,261 (260) (33) Mark-to-market derivative liabilities (472) (1,335) (2) 118 1,015 (204) (268) Total mark-to-market derivative liabilities (765) (3,964) (25) 249 3,276 (464) (301) Total mark-to-market derivative net assets (liabilities) $ 428 $ 294 $ 19 $ 416 $ — $ 729 $ (301) _________ (a) Exelon and Generation net all available amounts allowed under the derivative authoritative guidance in the balance sheet. These amounts include unrealized derivative transactions with the same counterparty under legally enforceable master netting agreements and cash collateral. In some cases Exelon and Generation may have other offsetting exposures, subject to a master netting or similar agreement, such as trade receivables and payables, transactions that do not qualify as derivatives, letters of credit, and other forms of non-cash collateral. These amounts are not material and not reflected in the table above. (b) Includes $858 million held and $209 million posted of variation margin with the exchanges as of June 30, 2021 and December 31, 2020 respectively.
Economic Hedges (Commodity Price Risk)	For the three and six months ended June 30, 2021 and 2020, Exelon and Generation recognized the following net pre-tax commodity mark-to-market gains (losses) which are also located in the Net fair value changes related to derivatives line in the Consolidated Statements of Cash Flows. Three Months Ended Six Months Ended 2021 2020 2021 2020 Income Statement Location Gain (Loss) Gain (Loss) Operating revenues $ (240) $ 24 $ (323) $ 199 Purchased power and fuel 552 63 817 15 Total Exelon and Generation $ 312 $ 87 $ 494 $ 214
Disclosure of Credit Derivatives [Table Text Block]	The following tables provide information on Generation’s credit exposure for all derivative instruments, NPNS, and payables and receivables, net of collateral and instruments that are subject to master netting agreements, as of June 30, 2021. The tables further delineate that exposure by credit rating of the counterparties and provide guidance on the concentration of credit risk to individual counterparties. The amounts in the tables below exclude credit risk exposure from individual retail counterparties, nuclear fuel procurement contracts, and exposure through RTOs, ISOs, NYMEX, ICE, NASDAQ, NGX, and Nodal commodity exchanges. Rating as of June 30, 2021 Total Exposure Before Credit Collateral Credit Collateral (a) Net Exposure Number of Counterparties Greater than 10% of Net Exposure Net Exposure of Counterparties Greater than 10% of Net Exposure Investment grade $ 446 $ 56 $ 390 — $ — Non-investment grade 15 1 14 No external ratings Internally rated — investment grade 134 1 133 Internally rated — non-investment grade 126 35 91 Total $ 721 $ 93 $ 628 — $ — Net Credit Exposure by Type of Counterparty As of June 30, 2021 Financial institutions $ 27 Investor-owned utilities, marketers, power producers 448 Energy cooperatives and municipalities 85 Other 68 Total $ 628 _________ (a) As of June 30, 2021, credit collateral held from counterparties where Generation had credit exposure included $53 million of cash and $40 million of letters of credit. The credit collateral does not include non-liquid collateral.
Fair Value of Derivatives with Credit- Risk Related Contingent Features [Table Text Block]	The aggregate fair value of all derivative instruments with credit-risk related contingent features in a liability position that are not fully collateralized (excluding transactions on the exchanges that are fully collateralized) is detailed in the table below: Credit-Risk Related Contingent Features June 30, 2021 December 31, 2020 Gross fair value of derivative contracts containing this feature (a) $ (2,173) $ (834) Offsetting fair value of in-the-money contracts under master netting arrangements (b) 1,151 537 Net fair value of derivative contracts containing this feature (c) $ (1,022) $ (297) _________ (a) Amount represents the gross fair value of out-of-the-money derivative contracts containing credit-risk related contingent features ignoring the effects of master netting agreements. (b) Amount represents the offsetting fair value of in-the-money derivative contracts under legally enforceable master netting agreements with the same counterparty, which reduces the amount of any liability for which Generation could potentially be required to post collateral. (c) Amount represents the net fair value of out-of-the-money derivative contracts containing credit-risk related contingent features after considering the mitigating effects of offsetting positions under master netting arrangements and reflects the actual net liability upon which any potential contingent collateral obligations would be based.
Cash Collateral and Letters of Credit on Derivative Contracts [Table Text Block]	As of June 30, 2021 and December 31, 2020, Exelon and Generation posted or held the following amounts of cash collateral and letters of credit on derivative contracts with external counterparties, after giving consideration to offsetting derivative and non-derivative positions under master netting agreements. June 30, 2021 December 31, 2020 Cash collateral posted $ 67 $ 511 Letters of credit posted 344 226 Cash collateral held 621 110 Letters of credit held 50 40 Additional collateral required in the event of a credit downgrade below investment grade 1,899 1,432

Debt and Credit Agreements (Tab

Debt and Credit Agreements (Tables)	6 Months Ended
Debt and Credit Agreements (Tables)	Jun. 30, 2021
Line of Credit Facility [Line Items]
Schedule of Commercial Paper Borrowings [Table Text Block]	The following table reflects the Registrants' commercial paper programs as of June 30, 2021 and December 31, 2020. PECO and BGE had no commercial paper borrowings as of both June 30, 2021 and December 31, 2020. Outstanding Commercial Average Interest Rate on Commercial Paper Issuer June 30, 2021 December 31, 2020 June 30, 2021 December 31, 2020 Exelon (a) $ 365 $ 1,031 0.17 % 0.25 % Generation — 340 — % 0.27 % ComEd 33 323 0.15 % 0.23 % PHI (b) 332 368 0.17 % 0.24 % Pepco 154 35 0.17 % 0.22 % DPL — 146 — % 0.24 % ACE 178 187 0.18 % 0.25 % __________ (a) Exelon Corporate had no outstanding commercial paper borrowings as of both June 30, 2021 and December 31, 2020. (b) Represents the consolidated amounts of Pepco, DPL, and ACE.
Schedule of Long-term Debt Instruments [Table Text Block]	During the six months ended June 30, 2021, the following long-term debt was issued: Company Type Interest Rate Maturity Amount Use of Proceeds Exelon Long-Term Software License Agreements 3.62 % December 1, 2025 $ 4 Procurement of software licenses. Generation West Medway II LIBOR + 3% (a) March 31, 2026 150 Funding for general corporate purposes. Generation Energy Efficiency Project Financing (b) 2.53 % August 31, 2021 1 Funding to install energy conservation measures for the Fort AP Hill project. ComEd First Mortgage Bonds, Series 130 3.13 % March 15, 2051 700 Repay a portion of outstanding commercial paper obligations and two outstanding term loans, and to fund other general corporate purposes. PECO First and Refunding Mortgage Bonds 3.05 % March 15, 2051 375 Funding for general corporate purposes. BGE Senior Notes 2.25 % June 15, 2031 600 Repay a portion of outstanding commercial paper obligations, repay existing indebtedness, and to fund other general corporate purposes. Pepco (c) First Mortgage Bonds 2.32 % March 30, 2031 150 Repay existing indebtedness and for general corporate purposes. DPL First Mortgage Bonds 3.24 % March 30, 2051 125 Repay existing indebtedness and for general corporate purposes. ACE First Mortgage Bonds 2.30 % March 15, 2031 350 Refinance existing indebtedness, repay outstanding commercial paper obligations, and for general corporate purposes. __________ (a) The nonrecourse debt has an average blended interest rate. (b) For Energy Efficiency Project Financing, the maturity dates represent the expected date of project completion, upon which the respective customer assumes the outstanding debt. (c) On March 30, 2021, Pepco entered into a purchase agreement of First Mortgage Bonds of $125 million at 3.29% due on September 28, 2051. The closing date of the issuance is expected to occur in September 2021.

Fair Value of Financial Asset_2

Fair Value of Financial Assets and Liabilities (Tables)	6 Months Ended
Fair Value of Financial Assets and Liabilities (Tables)	Jun. 30, 2021
Fair Value Disclosures [Abstract]
Fair Value of Financial Liabilities Recorded at Amortized Cost	Fair Value of Financial Liabilities Recorded at Amortized Cost The following tables present the carrying amounts and fair values of the Registrants’ short-term liabilities, long-term debt, SNF obligation, and trust preferred securities (long-term debt to financing trusts or junior subordinated debentures) as of June 30, 2021 and December 31, 2020. The Registrants have no financial liabilities classified as Level 1. The carrying amounts of the Registrants’ short-term liabilities as presented on their Consolidated Balance Sheets are representative of their fair value (Level 2) because of the short-term nature of these instruments. June 30, 2021 December 31, 2020 Carrying Amount Fair Value Carrying Amount Fair Value Level 2 Level 3 Total Level 2 Level 3 Total Long-Term Debt, including amounts due within one year (a) Exelon $ 38,710 $ 40,956 $ 3,189 $ 44,145 $ 36,912 $ 40,688 $ 3,064 $ 43,752 Generation 6,178 5,776 1,145 6,921 6,087 5,648 1,208 6,856 ComEd 9,675 11,407 — 11,407 8,983 11,117 — 11,117 PECO 4,125 4,722 50 4,772 3,753 4,553 50 4,603 BGE 4,259 4,748 — 4,748 3,664 4,366 — 4,366 PHI 7,369 6,048 1,994 8,042 7,006 6,099 1,806 7,905 Pepco 3,318 3,240 860 4,100 3,165 3,336 748 4,084 DPL 1,804 1,434 556 1,990 1,677 1,484 455 1,939 ACE 1,515 1,117 578 1,695 1,413 1,018 602 1,620 Long-Term Debt to Financing Trusts (a) Exelon $ 390 $ — $ 482 $ 482 $ 390 $ — $ 467 $ 467 ComEd 205 — 253 253 205 — 246 246 PECO 184 — 229 229 184 — 221 221 SNF Obligation Exelon $ 1,209 $ 995 $ — $ 995 $ 1,208 $ 909 $ — $ 909 Generation 1,209 995 — 995 1,208 909 — 909 __________ (a) Includes unamortized debt issuance costs which are not fair valued.
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block]	Recurring Fair Value Measurements The following tables present assets and liabilities measured and recorded at fair value in the Registrants' Consolidated Balance Sheets on a recurring basis and their level within the fair value hierarchy as of June 30, 2021 and December 31, 2020: Exelon and Generation Exelon Generation As of June 30, 2021 Level 1 Level 2 Level 3 Not subject to leveling Total Level 1 Level 2 Level 3 Not subject to leveling Total Assets Cash equivalents (a) $ 1,167 $ — $ — $ — $ 1,167 $ 162 $ — $ — $ — $ 162 NDT fund investments Cash equivalents (b) 552 75 — — 627 552 75 — — 627 Equities 4,770 1,720 — 1,671 8,161 4,770 1,720 — 1,671 8,161 Fixed income Corporate debt (c) — 1,146 285 — 1,431 — 1,146 285 — 1,431 U.S. Treasury and agencies 2,052 39 — — 2,091 2,052 39 — — 2,091 Foreign governments — 51 — — 51 — 51 — — 51 State and municipal debt — 28 — — 28 — 28 — — 28 Other 32 31 — 1,113 1,176 32 31 — 1,113 1,176 Fixed income subtotal 2,084 1,295 285 1,113 4,777 2,084 1,295 285 1,113 4,777 Private credit — — 176 607 783 — — 176 607 783 Private equity — — — 580 580 — — — 580 580 Real estate — — — 762 762 — — — 762 762 NDT fund investments subtotal (d)(e) 7,406 3,090 461 4,733 15,690 7,406 3,090 461 4,733 15,690 Rabbi trust investments Cash equivalents 65 — — — 65 4 — — — 4 Mutual funds 99 — — — 99 33 — — — 33 Fixed income — 11 — — 11 — — — — — Life insurance contracts — 94 34 — 128 — 31 — — 31 Rabbi trust investments subtotal 164 105 34 — 303 37 31 — — 68 Investments in equities (f) 327 — — — 327 327 — — — 327 Commodity derivative assets Economic hedges 1,781 3,917 2,840 — 8,538 1,781 3,917 2,840 — 8,538 Proprietary trading — 62 12 — 74 — 62 12 — 74 Effect of netting and allocation of collateral (g)(h) (1,411) (3,502) (2,513) — (7,426) (1,411) (3,502) (2,513) — (7,426) Commodity derivative assets subtotal 370 477 339 — 1,186 370 477 339 — 1,186 DPP consideration — 374 — — 374 — 374 — — 374 Exelon Generation As of June 30, 2021 Level 1 Level 2 Level 3 Not subject to leveling Total Level 1 Level 2 Level 3 Not subject to leveling Total Total assets 9,434 4,046 834 4,733 19,047 8,302 3,972 800 4,733 17,807 Liabilities Commodity derivative liabilities Economic hedges (1,245) (3,444) (3,390) — (8,079) (1,245) (3,444) (3,125) — (7,814) Proprietary trading — (45) (16) — (61) — (45) (16) — (61) Effect of netting and allocation of collateral (g)(h) 1,242 3,295 2,337 — 6,874 1,242 3,295 2,337 — 6,874 Commodity derivative liabilities subtotal (3) (194) (1,069) — (1,266) (3) (194) (804) — (1,001) Deferred compensation obligation — (144) — — (144) — (42) — — (42) Total liabilities (3) (338) (1,069) — (1,410) (3) (236) (804) — (1,043) Total net assets (liabilities) $ 9,431 $ 3,708 $ (235) $ 4,733 $ 17,637 $ 8,299 $ 3,736 $ (4) $ 4,733 $ 16,764 Exelon Generation As of December 31, 2020 Level 1 Level 2 Level 3 Not subject to leveling Total Level 1 Level 2 Level 3 Not subject to leveling Total Assets Cash equivalents (a) $ 686 $ — $ — $ — $ 686 $ 124 $ — $ — $ — $ 124 NDT fund investments Cash equivalents (b) 210 95 — — 305 210 95 — — 305 Equities 3,886 2,077 — 1,562 7,525 3,886 2,077 — 1,562 7,525 Fixed income Corporate debt (c) — 1,485 285 — 1,770 — 1,485 285 — 1,770 U.S. Treasury and agencies 1,871 126 — — 1,997 1,871 126 — — 1,997 Foreign governments — 56 — — 56 — 56 — — 56 State and municipal debt — 101 — — 101 — 101 — — 101 Other — 41 — 961 1,002 — 41 — 961 1,002 Fixed income subtotal 1,871 1,809 285 961 4,926 1,871 1,809 285 961 4,926 Private credit — — 212 629 841 — — 212 629 841 Private equity — — — 504 504 — — — 504 504 Real estate — — — 679 679 — — — 679 679 NDT fund investments subtotal (d)(e) 5,967 3,981 497 4,335 14,780 5,967 3,981 497 4,335 14,780 Rabbi trust investments Cash equivalents 60 — — — 60 4 — — — 4 Mutual funds 91 — — — 91 29 — — — 29 Fixed income — 11 — — 11 — — — — — Life insurance contracts — 87 34 — 121 — 28 — — 28 Rabbi trust investments subtotal 151 98 34 — 283 33 28 — — 61 Investments in equities (f) 195 — — — 195 195 — — — 195 Commodity derivative assets Economic hedges 745 1,914 1,599 — 4,258 745 1,914 1,599 — 4,258 Proprietary trading — 17 27 — 44 — 17 27 — 44 Exelon Generation As of December 31, 2020 Level 1 Level 2 Level 3 Not subject to leveling Total Level 1 Level 2 Level 3 Not subject to leveling Total Effect of netting and allocation of collateral (g)(h) (607) (1,597) (905) — (3,109) (607) (1,597) (905) — (3,109) Commodity derivative assets subtotal 138 334 721 — 1,193 138 334 721 — 1,193 DPP consideration — 639 — — 639 — 639 — — 639 Total assets 7,137 5,052 1,252 4,335 17,776 6,457 4,982 1,218 4,335 16,992 Liabilities Commodity derivative liabilities Economic hedges (682) (1,928) (1,655) — (4,265) (682) (1,928) (1,354) — (3,964) Proprietary trading — (21) (4) — (25) — (21) (4) — (25) Effect of netting and allocation of collateral (g)(h) 540 1,918 1,067 — 3,525 540 1,918 1,067 — 3,525 Commodity derivative liabilities subtotal (142) (31) (592) — (765) (142) (31) (291) — (464) Deferred compensation obligation — (145) — — (145) — (42) — — (42) Total liabilities (142) (176) (592) — (910) (142) (73) (291) — (506) Total net assets $ 6,995 $ 4,876 $ 660 $ 4,335 $ 16,866 $ 6,315 $ 4,909 $ 927 $ 4,335 $ 16,486 __________ (a) Exelon excludes cash of $728 million and $409 million at June 30, 2021 and December 31, 2020, respectively, and restricted cash of $114 million and $59 million at June 30, 2021 and December 31, 2020, respectively, and includes long-term restricted cash of $52 million and $53 million at June 30, 2021 and December 31, 2020, respectively, which is reported in Other deferred debits in the Consolidated Balance Sheets. Generation excludes cash of $407 million and $171 million at June 30, 2021 and December 31, 2020, respectively, and restricted cash of $32 million and $20 million at June 30, 2021 and December 31, 2020, respectively. (b) Includes $103 million and $116 million of cash received from outstanding repurchase agreements at June 30, 2021 and December 31, 2020, respectively, and is offset by an obligation to repay upon settlement of the agreement as discussed in (e) below. (c) Includes investments in equities sold short of $(52) million and $(62) million as of June 30, 2021 and December 31, 2020, respectively, held in an investment vehicle primarily to hedge the equity option component of its convertible debt. (d) Includes derivative assets of less than $1 million and $2 million, which have total notional amounts of $2,016 million and $1,043 million at June 30, 2021 and December 31, 2020, respectively. The notional principal amounts for these instruments provide one measure of the transaction volume outstanding as of the periods ended and do not represent the amount of Exelon and Generation's exposure to credit or market loss. (e) Excludes net liabilities of $94 million and $181 million at June 30, 2021 and December 31, 2020, respectively, which include certain derivative assets that have notional amounts of $137 million and $104 million at June 30, 2021 and December 31, 2020, respectively. These items consist of receivables related to pending securities sales, interest and dividend receivables, repurchase agreement obligations, and payables related to pending securities purchases. The repurchase agreements are generally short-term in nature with durations generally of 30 days or less. (f) Includes equity investments held by Generation which were previously designated as equity investments without readily determinable fair value but are now publicly traded and therefore have readily determinable fair values. The first investment became publicly traded in the fourth quarter of 2020. Generation recorded the fair value of these investments in Other current assets on Exelon's and Generation's Consolidated Balance Sheets based on the quoted market prices of the stocks at June 30, 2021, which resulted in unrealized gains for investments that became publicly traded during 2021 o f $102 million and $220 million within Other, net in Exelon's and Generation's Consolidated Statements of Operations and Comprehensive Income for the three and six months ended June 30, 2021, respectively. (g) Collateral (received) from counterparties, net of collateral paid to counterparties, totaled $(169) million, $(207) million, and $(176) million allocated to Level 1, Level 2, and Level 3 mark-to-market derivatives, respectively, as of June 30, 2021. Collateral (received)/posted from counterparties, net of collateral paid to counterparties, totaled $(67) million, $321 million, and $162 million allocated to Level 1, Level 2, and Level 3 mark-to-market derivatives, respectively, as of December 31, 2020. (h) Includes $858 million held and $209 million posted of variation margin with the exchanges as of June 30, 2021 and December 31, 2020, respectively. As of June 30, 2021, Exelon and Generation have outstanding commitments to invest in private credit, private equity, and real estate investments of approximately $364 million, $224 million, and $320 million, respectively. These commitments will be funded by Generation’s existing NDT funds. Exelon and Generation held investments without readily determinable fair values with carrying amounts of $38 million and $26 million as of June 30, 2021, respectively. Exelon and Generation held investments without readily determinable fair values with carrying amounts of $73 million and $55 million as of December 31, 2020, respectively. Changes in fair value, cumulative adjustments, and impairments were not material for the three and six months ended June 30, 2021 and for the year ended December 31, 2020. ComEd, PECO, and BGE ComEd PECO BGE As of June 30, 2021 Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Assets Cash equivalents (a) $ 264 $ — $ — $ 264 $ 230 $ — $ — $ 230 $ 334 $ — $ — $ 334 Rabbi trust investments Mutual funds — — — — 10 — — 10 14 — — 14 Life insurance contracts — — — — — 15 — 15 — — — — Rabbi trust investments subtotal — — — — 10 15 — 25 14 — — 14 Total assets 264 — — 264 240 15 — 255 348 — — 348 Liabilities Deferred compensation obligation — (9) — (9) — (8) — (8) — (6) — (6) Mark-to-market derivative liabilities (b) — — (265) (265) — — — — — — — — Total liabilities — (9) (265) (274) — (8) — (8) — (6) — (6) Total net assets (liabilities) $ 264 $ (9) $ (265) $ (10) $ 240 $ 7 $ — $ 247 $ 348 $ (6) $ — $ 342 ComEd PECO BGE As of December 31, 2020 Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Assets Cash equivalents (a) $ 285 $ — $ — $ 285 $ 8 $ — $ — $ 8 $ 120 $ — $ — $ 120 Rabbi trust investments Mutual funds — — — — 9 — — 9 10 — — 10 Life insurance contracts — — — — — 13 — 13 — — — — Rabbi trust investments subtotal — — — — 9 13 — 22 10 — — 10 Total assets 285 — — 285 17 13 — 30 130 — — 130 Liabilities Deferred compensation obligation — (8) — (8) — (9) — (9) — (5) — (5) Mark-to-market derivative liabilities (b) — — (301) (301) — — — — — — — — Total liabilities — (8) (301) (309) — (9) — (9) — (5) — (5) Total net assets (liabilities) $ 285 $ (8) $ (301) $ (24) $ 17 $ 4 $ — $ 21 $ 130 $ (5) $ — $ 125 __________ (a) ComEd excludes cash of $44 million and $83 million at June 30, 2021 and December 31, 2020, respectively, and restricted cash of $46 million and $37 million at June 30, 2021 and December 31, 2020, respectively, and includes long-term restricted cash of $43 million at both June 30, 2021 and December 31, 2020, respectively, which is reported in Other deferred debits in the Consolidated Balance Sheets. PECO excludes cash of $154 million and $18 million at June 30, 2021 and December 31, 2020, respectively. BGE excludes cash of $34 million and $24 million at June 30, 2021 and December 31, 2020, respectively, and restricted cash of $3 million and $1 million at June 30, 2021 and December 31, 2020, respectively. (b) The Level 3 balance consists of the current and noncurrent liability of $23 million and $242 million, respectively, at June 30, 2021 and $33 million and $268 million, respectively, at December 31, 2020 related to floating-to-fixed energy swap contracts with unaffiliated suppliers. PHI, Pepco, DPL, and ACE As of June 30, 2021 As of December 31, 2020 PHI Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Assets Cash equivalents (a) $ 46 $ — $ — $ 46 $ 86 $ — $ — $ 86 Rabbi trust investments Cash equivalents 59 — — 59 55 — — 55 Mutual funds 14 — — 14 14 — — 14 Fixed income — 11 — 11 — 11 — 11 Life insurance contracts — 26 34 60 — 26 34 60 Rabbi trust investments subtotal 73 37 34 144 69 37 34 140 Total assets 119 37 34 190 155 37 34 226 Liabilities Deferred compensation obligation — (16) — (16) — (17) — (17) Total liabilities — (16) — (16) — (17) — (17) Total net assets $ 119 $ 21 $ 34 $ 174 $ 155 $ 20 $ 34 $ 209 Pepco DPL ACE As of June 30, 2021 Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Assets Cash equivalents (a) $ 28 $ — $ — $ 28 $ 5 $ — $ — $ 5 $ 12 $ — $ — $ 12 Rabbi trust investments Cash equivalents 57 — — 57 — — — — — — — — Fixed income — 2 — 2 — — — — — — — — Life insurance contracts — 26 34 60 — — — — — — — — Rabbi trust investments subtotal 57 28 34 119 — — — — — — — — Total assets 85 28 34 147 5 — — 5 12 — — 12 Liabilities Deferred compensation obligation — (2) — (2) — — — — — — — — Total liabilities — (2) — (2) — — — — — — — — Total net assets $ 85 $ 26 $ 34 $ 145 $ 5 $ — $ — $ 5 $ 12 $ — $ — $ 12 Pepco DPL ACE As of December 31, 2020 Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Assets Cash equivalents (a) $ 35 $ — $ — $ 35 $ — $ — $ — $ — $ 13 $ — $ — $ 13 Rabbi trust investments Cash equivalents 53 — — 53 — — — — — — — — Fixed income — 2 — 2 — — — — — — — — Life insurance contracts — 26 34 60 — — — — — — — — Rabbi trust investments subtotal 53 28 34 115 — — — — — — — — Total assets 88 28 34 150 — — — — 13 — — 13 Liabilities Deferred compensation obligation — (2) — (2) — — — — — — — — Total liabilities — (2) — (2) — — — — — — — — Total net assets $ 88 $ 26 $ 34 $ 148 $ — $ — $ — $ — $ 13 $ — $ — $ 13 __________ (a) PHI excludes cash of $61 million and $74 million at June 30, 2021 and December 31, 2020, respectively, and restricted cash of $5 million and none at June 30, 2021 and December 31, 2020, respectively, and includes long-term restricted cash of $9 million and $10 million at June 30, 2021 and December 31, 2020, respectively, which is reported in Other deferred debits in the Consolidated Balance Sheets. Pepco excludes cash of $17 million and $30 million at June 30, 2021 and December 31, 2020, respectively, and restricted cash of $5 million and none at June 30, 2021 and December 31, 2020, respectively. DPL excludes cash of $17 million and $15 million at June 30, 2021 and December 31, 2020, respectively. ACE excludes cash of $11 million and $17 million at June 30, 2021 and December 31, 2020, respectively, and includes long-term restricted cash of $9 million and $10 million at June 30, 2021 and December 31, 2020, respectively, which is reported in Other deferred debits in the Consolidated Balance Sheets.
Fair Value Reconciliation of Level 3 Assets and Liabilities Measured at Fair Value on a Recurring Basis	Reconciliation of Level 3 Assets and Liabilities The following tables present the fair value reconciliation of Level 3 assets and liabilities measured at fair value on a recurring basis during the three and six months ended June 30, 2021 and 2020: Exelon Generation ComEd PHI and Pepco Three Months Ended June 30, 2021 Total NDT Fund Mark-to-Market Total Generation Mark-to-Market Life Insurance Contracts Eliminated in Consolidation Balance as of March 31, 2021 $ 426 $ 479 $ 207 $ 686 $ (295) $ 35 $ — Total realized / unrealized gains (losses) Included in net income (357) 1 (359) (a) (358) — 1 — Included in noncurrent payables to affiliates — 6 — 6 — — (6) Included in regulatory assets 36 — — — 30 (b) — 6 Change in collateral (282) — (282) (282) — — — Purchases, sales, and settlements Purchases 7 1 6 7 — — — Sales 1 — 1 1 — — — Settlements (28) (26) — (26) — (2) — Transfers into Level 3 1 — 1 (c) 1 — — — Transfers out of Level 3 (39) — (39) (c) (39) — — — Balance at June 30, 2021 $ (235) $ 461 $ (465) $ (4) $ (265) $ 34 $ — The amount of total (losses) gains included in income attributed to the change in unrealized gains (losses) related to assets and liabilities as of June 30, 2021 $ (372) $ 1 $ (374) $ (373) $ — $ 1 $ — Exelon Generation ComEd PHI and Pepco Six months ended June 30, 2021 Total NDT Fund Mark-to-Market Total Generation Mark-to-Market Life Insurance Contracts Eliminated in Consolidation Balance as of December 31, 2020 $ 660 $ 497 $ 430 $ 927 $ (301) $ 34 $ — Total realized / unrealized gains (losses) Included in net income (632) 2 (636) (a) (634) — 2 — Included in noncurrent payables to affiliates — 7 — 7 — — (7) Included in regulatory assets 43 — — — 36 (b) — 7 Change in collateral (338) — (338) (338) — — — Purchases, sales, and settlements Purchases 115 1 114 115 — — — Sales 1 — 1 1 — — — Settlements (48) (46) — (46) — (2) — Transfers into Level 3 1 — 1 (c) 1 — — — Transfers out of Level 3 (37) — (37) (c) (37) — — — Balance as of June 30, 2021 $ (235) $ 461 $ (465) $ (4) $ (265) $ 34 $ — The amount of total (losses) gains included in income attributed to the change in unrealized gains (losses) related to assets and liabilities as of June 30, 2021 $ (518) $ 2 $ (522) $ (520) $ — $ 2 $ — Exelon Generation ComEd PHI and Pepco Three Months Ended June 30, 2020 Total NDT Fund Mark-to-Market Total Generation Mark-to-Market Life Insurance Contracts Eliminated in Consolidation Balance as of March 31, 2020 $ 1,088 $ 498 $ 862 $ 1,360 $ (314) $ 42 $ — Total realized / unrealized gains (losses) Included in net income (166) (1) (166) (a) (167) — 1 — Included in regulatory assets/liabilities (4) — — — (4) (b) — — Change in collateral (42) — (42) (42) — — — Purchases, sales, and settlements Purchases 30 3 27 30 — — — Sales (2) — (2) (2) — — — Settlements (1) (1) — (1) — — — Transfers into Level 3 (9) — (9) (c) (9) — — — Transfers out of Level 3 (11) — (11) (c) (11) — — — Balance as of June 30, 2020 $ 883 $ 499 $ 659 $ 1,158 $ (318) $ 43 $ — The amount of total (losses) gains included in income attributed to the change in unrealized gains (losses) related to assets and liabilities as of June 30, 2020 $ (72) $ (1) $ (72) $ (73) $ — $ 1 $ — Exelon Generation ComEd PHI and Pepco Six Months Ended June 30, 2020 Total NDT Fund Mark-to-Market Total Generation Mark-to-Market Life Insurance Contracts Eliminated in Consolidation Balance as of December 31, 2019 $ 1,068 $ 511 $ 817 $ 1,328 $ (301) $ 41 $ — Total realized / unrealized gains (losses) Included in net income (156) (2) (156) (a) (158) — 2 — Included in noncurrent payables to affiliates — (1) — (1) — — 1 Included in regulatory assets (18) — — — (17) (b) — (1) Change in collateral (41) — (41) (41) — — — Purchases, sales, and settlements Purchases 71 6 65 71 — — — Sales (24) — (24) (24) — — — Settlements (15) (15) — (15) — — — Transfers into Level 3 (6) — (6) (c) (6) — — — Transfers out of Level 3 4 — 4 (c) 4 — — — Balance as of June 30, 2020 $ 883 $ 499 $ 659 $ 1,158 $ (318) $ 43 $ — The amount of total gains (losses) included in income attributed to the change in unrealized gains (losses) related to assets and liabilities as of June 30, 2020 $ 115 $ (2) $ 115 $ 113 $ — $ 2 $ — __________ (a) Includes an addition of $15 million for realized losses and a reduction of $114 million for realized gains due to the settlement of derivative contracts for the three and six months ended June 30, 2021. Includes a reduction of $94 million and $271 million for realized gains due to the settlement of derivative contracts for the three and six months ended June 30, 2020. (b) Includes $25 million of increases in fair value and an increase for realized losses due to settlements of $5 million recorded in purchased power expense associated with floating-to-fixed energy swap contracts with unaffiliated suppliers for the three months ended June 30, 2021. Includes $23 million of increases in fair value and an increase for realized losses due to settlements of $13 million recorded in purchased power expense associated with floating-to-fixed energy swap contracts with unaffiliated suppliers for the six months ended June 30, 2021. Includes $12 million of decreases in fair value and an increase for realized losses due to settlements of $8 million recorded in purchased power expense associated with floating-to-fixed energy swap contracts with unaffiliated suppliers for the three months ended June 30, 2020. Includes $35 million of decrease in fair value and an increase for realized losses due to settlements of $18 million recorded in purchased power expense associated with floating-to-fixed energy swap contracts with unaffiliated suppliers for the six months ended June 30, 2020. (c) Transfers into and out of Level 3 generally occur when the contract tenor becomes less and more observable respectively, primarily due to changes in market liquidity or assumptions for certain commodity contracts.
Total Realized and Unrealized Gains (Losses) Included in Income for Level 3 Assets and Liabilities Measured at Fair Value on a Recurring Basis	The following tables present the income statement classification of the total realized and unrealized gains (losses) included in income for Level 3 assets and liabilities measured at fair value on a recurring basis during the three and six months ended June 30, 2021 and 2020: Exelon Generation PHI and Pepco Operating Purchased Operating and Maintenance Other, net Operating Purchased Other, net Operating and Maintenance Total (losses) gains included in net income for the three months ended June 30, 2021 $ (555) $ 196 $ 1 $ 1 $ (555) $ 196 $ 1 $ 1 Total (losses) gain included in net income for the six months ended June 30, 2021 (670) 34 2 2 (670) 34 2 2 Total unrealized (losses) gains for the three months ended June 30, 2021 (543) 169 1 1 (543) 169 1 1 Total unrealized (losses) gains for the six months ended June 30, 2021 (608) 86 2 2 (608) 86 2 2 Exelon Generation PHI and Pepco Operating Purchased Operating and Maintenance Other, net Operating Purchased Other, net Operating and Maintenance Total (losses) gains included in net income for the three months ended June 30, 2020 $ (137) $ (29) $ 1 $ — $ (137) $ (29) $ — $ 1 Total (losses) gains included in net income for the six months ended June 30, 2020 (65) (91) 2 — (65) (91) — 2 Total unrealized (losses) gains for the three months ended June 30, 2020 (39) (33) 1 (1) (39) (33) (1) 1 Total unrealized gains (losses) for the six months ended June 30, 2020 166 (51) 2 (2) 166 (51) (2) 2
Fair Value Reconciliation of Level 3 Assets and Liabilities Measured at Fair Value on a Recurring Basis, Valuation Technique	Mark-to-Market Derivatives (Exelon, Generation, and ComEd) The table below discloses the significant inputs to the forward curve used to value mark-to-market derivatives. Type of trade Fair Value at June 30, 2021 Fair Value at December 31, 2020 Valuation Unobservable 2021 Range & Arithmetic Average 2020 Range & Arithmetic Average Mark-to-market derivatives — Economic Hedges (Exelon and Generation) (a)(b) $ (285) $ 245 Discounted Forward power $7.13 - $281 $39 $2.25 - $163 $30 Forward gas $1.53 - $12.51 $3.10 $1.57 - $7.88 $2.59 Option Volatility 11% - 209% 33% 11% - 237% 32% Mark-to-market derivatives — Proprietary trading (Exelon and Generation) (a)(b) $ (4) $ 23 Discounted Forward power $10 - $132 $38 $10 - $106 $27 Mark-to-market derivatives (Exelon and ComEd) $ (265) $ (301) Discounted Forward heat (c) 9x - 10x 9.13x 8x - 9x 8.85x Marketability 3% - 7% 4.77% 3% - 8% 4.93% Renewable 94% - 122% 99% 91% - 123% 99% __________ (a) The valuation techniques, unobservable inputs, ranges and arithmetic averages are the same for the asset and liability positions. (b) The fair values do not include cash collateral (received)/posted on level three positions of $(176) million and $162 million as of June 30, 2021 and December 31, 2020, respectively. (c) Quoted forward natural gas rates are utilized to project the forward power curve for the delivery of energy at specified future dates. The natural gas curve is extrapolated beyond its observable period to the end of the contract’s delivery.

Commitments and Contingencies_2

Commitments and Contingencies (Tables)	6 Months Ended
Commitments and Contingencies (Tables)	Jun. 30, 2021
Commitments and Contingencies Disclosure [Abstract]
PHI Merger Commitments	The following amounts represent total commitment costs that have been recorded since the acquisition date and the total remaining obligations for Exelon, PHI, Pepco, DPL, and ACE as of June 30, 2021: Description Exelon PHI Pepco DPL ACE Total commitments $ 513 $ 320 $ 120 $ 89 $ 111 Remaining commitments (a) 76 63 52 7 4 __________ (a) Remaining commitments extend through 2026 and include rate credits, energy efficiency programs and delivery system modernization.
Commercial Commitments	The Registrants’ commercial commitments as of June 30, 2021, representing commitments potentially triggered by future events were as follows: Expiration within Total 2021 2022 2023 2024 2025 2026 and beyond Exelon Letters of credit $ 1,751 $ 591 $ 1,160 $ — $ — $ — $ — Surety bonds (a) 920 619 299 — 2 — — Financing trust guarantees 378 — — — — — 378 Guaranteed lease residual values (b) 30 — 3 3 6 6 12 Total commercial commitments $ 3,079 $ 1,210 $ 1,462 $ 3 $ 8 $ 6 $ 390 Generation Letters of credit $ 1,735 $ 578 $ 1,157 $ — $ — $ — $ — Surety bonds (a) 772 514 258 — — — — Total commercial commitments $ 2,507 $ 1,092 $ 1,415 $ — $ — $ — $ — ComEd Letters of credit $ 7 $ 7 $ — $ — $ — $ — $ — Surety bonds (a) 17 9 6 — 2 — — Financing trust guarantees 200 — — — — — 200 Total commercial commitments $ 224 $ 16 $ 6 $ — $ 2 $ — $ 200 PECO Surety bonds (a) $ 3 $ 1 $ 2 $ — $ — $ — $ — Financing trust guarantees 178 — — — — — 178 Total commercial commitments $ 181 $ 1 $ 2 $ — $ — $ — $ 178 BGE Letters of credit $ 2 $ — $ 2 $ — $ — $ — $ — Surety bonds (a) 3 2 1 — — — — Total commercial commitments $ 5 $ 2 $ 3 $ — $ — $ — $ — PHI Surety bonds (a) $ 25 $ 8 $ 17 $ — $ — $ — $ — Guaranteed lease residual values (b) 30 — 3 3 6 6 12 Total commercial commitments $ 55 $ 8 $ 20 $ 3 $ 6 $ 6 $ 12 Pepco Surety bonds (a) $ 17 $ 4 $ 13 $ — $ — $ — $ — Guaranteed lease residual values (b) 10 — 1 1 2 2 4 Total commercial commitments $ 27 $ 4 $ 14 $ 1 $ 2 $ 2 $ 4 DPL Surety bonds (a) $ 4 $ 2 $ 2 $ — $ — $ — $ — Guaranteed lease residual values (b) 13 — 1 1 3 3 5 Total commercial commitments $ 17 $ 2 $ 3 $ 1 $ 3 $ 3 $ 5 ACE Surety bonds (a) $ 4 $ 2 $ 2 $ — $ — $ — $ — Guaranteed lease residual values (b) 7 — 1 1 1 1 3 Total commercial commitments $ 11 $ 2 $ 3 $ 1 $ 1 $ 1 $ 3 __________ (a) Surety bonds—Guarantees issued related to contract and commercial agreements, excluding bid bonds. (b) Represents the maximum potential obligation in the event that the fair value of certain leased equipment and fleet vehicles is zero at the end of the maximum lease term. The lease term associated with these assets ranges from 1 to 8 years. The maximum potential obligation at the end of the minimum lease term would be $75 million guaranteed by Exelon and PHI, of which $26 million, $31 million, and $18 million is guaranteed by Pepco, DPL, and ACE, respectively. Historically, payments under the guarantees have not been made and PHI believes the likelihood of payments being required under the guarantees is remote.
Accrued environmental liabilities	As of June 30, 2021 and December 31, 2020, the Registrants had accrued the following undiscounted amounts for environmental liabilities in Other current liabilities and Other deferred credits and other liabilities within their respective Consolidated Balance Sheets: June 30, 2021 December 31, 2020 Total environmental Portion of total related to Total environmental Portion of total related to Exelon $ 461 $ 297 $ 483 $ 314 Generation 117 — 121 — ComEd 273 272 293 293 PECO 22 20 23 21 BGE 6 5 2 — PHI 43 — 44 — Pepco 41 — 42 — DPL 1 — 1 — ACE 1 — 1 —

Changes in Accumulated Other _2

Changes in Accumulated Other Comprehensive Income (Tables)	6 Months Ended
Changes in Accumulated Other Comprehensive Income (Tables)	Jun. 30, 2021
Changes in Accumulated Other Comprehensive Income [Abstract]
Schedule of Changes in Accumulated Other Comprehensive Income (Loss)	The following tables present changes in Exelon's AOCI, net of tax, by component: Three Months Ended June 30, 2021 Losses on Cash Flow Hedges Pension and Non-Pension Postretirement Benefit Plan Items (a) Foreign Total Beginning balance $ (5) $ (3,319) $ (22) $ (3,346) OCI before reclassifications — — 2 2 Amounts reclassified from AOCI — 55 — 55 Net current-period OCI — 55 2 57 Ending balance $ (5) $ (3,264) $ (20) $ (3,289) Three Months Ended June 30, 2020 Losses on Cash Flow Hedges Pension and Non-Pension Postretirement Benefit Plan Items (a) Foreign Total Beginning balance $ (3) $ (3,135) $ (35) $ (3,173) OCI before reclassifications — 2 2 4 Amounts reclassified from AOCI — 37 — 37 Net current-period OCI — 39 2 41 Ending balance $ (3) $ (3,096) $ (33) $ (3,132) Six Months Ended June 30, 2021 Losses on Cash Flow Hedges Pension and Non-Pension Postretirement Benefit Plan Items (a) Foreign Total Beginning balance $ (5) $ (3,372) $ (23) $ (3,400) OCI before reclassifications — (2) 3 1 Amounts reclassified from AOCI — 110 — 110 Net current-period OCI — 108 3 111 Ending balance $ (5) $ (3,264) $ (20) $ (3,289) Six Months Ended June 30, 2020 Losses on Cash Flow Hedges Pension and Non-Pension Postretirement Benefit Plan Items (a) Foreign Total Beginning balance $ (2) $ (3,165) $ (27) $ (3,194) OCI before reclassifications (1) (5) (6) (12) Amounts reclassified from AOCI — 74 — 74 Net current-period OCI (1) 69 (6) 62 Ending balance $ (3) $ (3,096) $ (33) $ (3,132) ______
Schedule Of Other Comprehensive Income (Loss) Tax	The following table presents income tax benefit (expense) allocated to each component of Exelon's other comprehensive income (loss): Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 Pension and non-pension postretirement benefit plans: Prior service benefit reclassified to periodic benefit cost $ 1 $ 4 $ 2 $ 8 Actuarial loss reclassified to periodic benefit cost (19) (17) (38) (34) Pension and non-pension postretirement benefit plans valuation adjustment (1) — (1) 3

Variable Interest Entities (Tab

Variable Interest Entities (Tables)	6 Months Ended
Variable Interest Entities (Tables)	Jun. 30, 2021
Variable Interest Entity [Abstract]
VIE - Assets and Liabilities of VIEs which Creditors or Beneficiaries have no Recourse	Consolidated VIEs The table below shows the carrying amounts and classification of the consolidated VIEs’ assets and liabilities included in the consolidated financial statements of Exelon, Generation, PHI, and ACE as of June 30, 2021 and December 31, 2020. The assets, except as noted in the footnotes to the table below, can only be used to settle obligations of the VIEs. The liabilities, except as noted in the footnote to the table below, are such that creditors, or beneficiaries, do not have recourse to the general credit of Exelon, Generation, PHI, and ACE. June 30, 2021 December 31, 2020 Exelon Generation PHI (a) ACE Exelon Generation PHI (a) ACE Cash and cash equivalents $ 233 $ 233 $ — $ — $ 98 $ 98 $ — $ — Restricted cash and cash equivalents 57 54 3 3 47 44 3 3 Accounts receivable Customer 169 169 — — 148 148 — — Other 44 44 — — 36 36 — — Unamortized energy contract assets 22 22 — — 22 22 — — Inventories, net Materials and supplies 255 255 — — 244 244 — — Assets held for sale (b) — — — — 101 101 — — Other current assets 408 404 4 — 674 669 5 — Total current assets 1,188 1,181 7 3 1,370 1,362 8 3 Property, plant, and equipment, net 5,656 5,656 — — 5,803 5,803 — — Nuclear decommissioning trust funds 3,215 3,215 — — 3,007 3,007 — — Unamortized energy contract assets 237 237 — — 249 249 — — Other noncurrent assets 35 26 9 9 52 42 10 10 Total noncurrent assets 9,143 9,134 9 9 9,111 9,101 10 10 Total assets (c) $ 10,331 $ 10,315 $ 16 $ 12 $ 10,481 $ 10,463 $ 18 $ 13 Long-term debt due within one year $ 84 $ 69 $ 15 $ 11 $ 94 $ 68 $ 26 $ 21 Accounts payable 67 67 — — 81 81 — — Accrued expenses 56 56 — — 70 70 — — Unamortized energy contract liabilities 1 1 — — 4 4 — — Liabilities held for sale (b) — — — — 16 16 — — Other current liabilities 1 1 — — 5 5 — — Total current liabilities 209 194 15 11 270 244 26 21 Long-term debt 860 860 — — 889 889 — — Asset retirement obligations 2,377 2,377 — — 2,318 2,318 — — Other noncurrent liabilities 133 133 — — 129 129 — — Total noncurrent liabilities 3,370 3,370 — — 3,336 3,336 — — Total liabilities (d) $ 3,579 $ 3,564 $ 15 $ 11 $ 3,606 $ 3,580 $ 26 $ 21 _________ (a) Includes certain purchase accounting adjustments from the PHI merger not pushed down to ACE. (b) In the fourth quarter of 2020, Generation entered into an agreement for the sale of a significant portion of Generation's solar business, and as a result of this transaction, Exelon and Generation reclassified the consolidated VIEs' solar assets and liabilities as held for sale. Completion of the transaction occurred in the first quarter of 2021. Refer to Note 2 - Mergers, Acquisitions, and Dispositions for additional information on the solar business. (c) Exelon’s and Generation’s balances include unrestricted assets for current unamortized energy contract assets of $22 million and $22 million, non-current unamortized energy contract assets of $216 million and $249 million, assets held for sale of $0 million and $9 million, and other unrestricted assets of $0 million and $1 million as of June 30, 2021 and December 31, 2020, respectively (d) Exelon’s and Generation’s balances include liabilities with recourse of $1 million and $8 million as of June 30, 2021 and December 31, 2020, respectively.
VIE - Summary of Unconsolidated VIEs	The following table presents summary information about Exelon's and Generation’s significant unconsolidated VIE entities: June 30, 2021 December 31, 2020 Commercial Equity Total Commercial Equity Total Total assets (a) $ 786 $ 378 $ 1,164 $ 777 $ 401 $ 1,178 Total liabilities (a) 95 210 305 61 223 284 Exelon's ownership interest in VIE (a) — 149 149 — 157 157 Other ownership interests in VIE (a) 691 19 710 716 21 737 _________ (a) These items represent amounts on the unconsolidated VIE balance sheets, not in Exelon’s or Generation’s Consolidated Balance Sheets. These items are included to provide information regarding the relative size of the unconsolidated VIEs. Exelon and Generation do not have any exposure to loss as they do not have a carrying amount in the equity investment VIEs as of June 30, 2021 and December 31, 2020.

Supplemental Financial Inform_2

Supplemental Financial Information (Tables)	6 Months Ended
Supplemental Financial Information (Tables)	Jun. 30, 2021
Supplemental Financial Information [Abstract]
Components of Operating Lease Income	The following tables provide additional information about material items recorded in the Registrants' Consolidated Statements of Operations and Comprehensive Income. Operating revenues Exelon Generation PHI DPL Three Months Ended June 30, 2021 Operating lease income $ 13 $ 12 $ 1 $ 1 Variable lease income 74 74 — — Three Months Ended June 30, 2020 Operating lease income $ 14 $ 12 $ 1 $ 1 Variable lease income 80 79 1 1 Six Months Ended June 30, 2021 Operating lease income $ 17 $ 15 $ 2 $ 2 Variable lease income 137 137 — — Six Months Ended June 30, 2020 Operating lease income $ 18 $ 15 $ 2 $ 2 Variable lease income 149 148 1 1
Taxes Other Than Income Taxes	Taxes other than income taxes Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE Three Months Ended June 30, 2021 Utility taxes (a) $ 206 $ 22 $ 61 $ 32 $ 20 $ 71 $ 65 $ 5 $ — Property 153 66 8 4 43 31 20 10 1 Payroll 61 30 6 4 5 7 1 1 1 Three Months Ended June 30, 2020 Utility taxes (a) $ 196 $ 23 $ 55 $ 31 $ 18 $ 69 $ 64 $ 5 $ — Property 149 64 8 4 40 33 21 11 1 Payroll 61 28 7 4 4 7 2 1 1 Six Months Ended June 30, 2021 Utility taxes (a) $ 423 $ 46 $ 121 $ 66 $ 45 $ 145 $ 132 $ 11 $ 1 Property 307 133 16 9 85 63 42 19 1 Payroll 122 58 13 8 9 14 3 3 2 Six Months Ended June 30, 2020 Utility taxes (a) $ 414 $ 49 $ 114 $ 62 $ 44 $ 145 $ 133 $ 10 $ 1 Property 297 133 15 8 79 62 41 20 1 Payroll 125 60 14 8 9 15 4 2 2 __________ (a) Generation’s utility tax represents gross receipts tax related to its retail operations, and the Utility Registrants' utility taxes represents municipal and state utility taxes and gross receipts taxes related to their operating revenues. The offsetting collection of utility taxes from customers is recorded in revenues in the Registrants’ Consolidated Statements of Operations and Comprehensive Income.
Schedule of Other Nonoperating Income, by Component	Other, Net Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE Three Months Ended June 30, 2021 Decommissioning-related activities: Net realized income on NDT funds (a) Regulatory Agreement Units $ 144 $ 144 $ — $ — $ — $ — $ — $ — $ — Non-Regulatory Agreement Units 87 87 — — — — — — — Net unrealized gains on NDT funds Regulatory Agreement Units 361 361 — — — — — — — Non-Regulatory Agreement Units 193 193 — — — — — — — Regulatory offset to NDT fund-related activities (b) (402) (402) — — — — — — — Decommissioning-related activities 383 383 — — — — — — — AFUDC — Equity 35 — 9 6 7 12 10 1 1 Non-service net periodic benefit cost 26 — — — — — — — — Net unrealized gains from equity investments (c) 119 119 — — — — — — — Three Months Ended June 30, 2020 Decommissioning-related activities: Net realized income on NDT funds (a) Regulatory Agreement Units $ 30 $ 30 $ — $ — $ — $ — $ — $ — $ — Non-Regulatory Agreement Units 23 23 — — — — — — — Net unrealized gains on NDT funds Regulatory Agreement Units 645 645 — — — — — — — Non-Regulatory Agreement Units 452 452 — — — — — — — Regulatory offset to NDT fund-related activities (b) (542) (542) — — — — — — — Decommissioning-related activities 608 608 — — — — — — — AFUDC — Equity 26 — 8 4 6 8 6 1 1 Non-service net periodic benefit cost 14 — — — — — — — — Other, net Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE Six Months Ended June 30, 2021 Decommissioning-related activities: Net realized income on NDT funds (a) Regulatory Agreement Units $ 435 $ 435 $ — $ — $ — $ — $ — $ — $ — Non-Regulatory Agreement Units 290 290 — — — — — — — Net unrealized gains on NDT funds Regulatory Agreement Units 279 279 — — — — — — — Non-Regulatory Agreement Units 126 126 — — — — — — — Regulatory offset to NDT fund-related activities (b) (569) (569) — — — — — — — Decommissioning-related activities 561 561 — — — — — — — AFUDC — Equity 64 — 13 12 14 25 20 3 2 Non-service net periodic benefit cost 46 — — — — — — — — Net unrealized gains from equity investments (c) 96 96 — — — — — — — Six Months Ended June 30, 2020 Decommissioning-related activities: Net realized income on NDT funds (a) Regulatory Agreement Units $ 77 $ 77 $ — $ — $ — $ — $ — $ — $ — Non-Regulatory Agreement Units 104 104 — — — — — — — Net unrealized gains on NDT funds Regulatory Agreement Units (287) (287) — — — — — — — Non-Regulatory Agreement Units (253) (253) — — — — — — — Regulatory offset to NDT fund-related activities (b) 167 167 — — — — — — — Decommissioning-related activities (192) (192) — — — — — — — AFUDC — Equity 49 — 14 7 10 17 13 2 2 Non-service net periodic benefit cost 24 — — — — — — — — __________ (a) Realized income includes interest, dividends and realized gains and losses on sales of NDT fund investments. (b) Includes the elimination of decommissioning-related activities for the Regulatory Agreement Units except for decommissioning-related impacts that were not offset for the Byron units in the second quarter of 2021, including the elimination of income taxes related to all NDT fund activity for those units. See Note 10 — Asset Retirement Obligations of the Exelon 2020 Form 10-K for additional information regarding the accounting for nuclear decommissioning and Note 8 — Nuclear Decommissioning for additional information on the contractual offset suspension for the Byron units. (c) Net unrealized gains from equity investments that became publicly traded entities in the fourth quarter of 2020 and the first half of 2021.
Cash Flow Supplemental Disclosures	The following tables provide additional information about material items recorded in the Registrants' Consolidated Statements of Cash Flows. Depreciation, amortization and accretion Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE Six Months Ended June 30, 2021 Property, plant, and equipment (a) $ 3,043 $ 1,844 $ 480 $ 165 $ 215 $ 309 $ 135 $ 84 $ 76 Amortization of regulatory assets (a) 291 — 109 8 78 95 64 20 11 Amortization of intangible assets, net (a) 29 25 — — — — — — — Amortization of energy contract assets and liabilities (b) 13 13 — — — — — — — Nuclear fuel (c) 549 549 — — — — — — — ARO accretion (d) 255 255 — — — — — — — Total depreciation, amortization and accretion $ 4,180 $ 2,686 $ 589 $ 173 $ 293 $ 404 $ 199 $ 104 $ 87 Six Months Ended June 30, 2020 Property, plant, and equipment (a) $ 1,715 $ 577 $ 458 $ 159 $ 195 $ 289 $ 126 $ 76 $ 69 Amortization of regulatory assets (a) 277 — 89 14 77 96 60 18 17 Amortization of intangible assets, net (a) 31 27 — — — — — — — Amortization of energy contract assets and liabilities (b) 12 10 — — — — — — — Nuclear fuel (c) 459 459 — — — — — — — ARO accretion (d) 247 247 — — — — — — — Total depreciation, amortization and accretion $ 2,741 $ 1,320 $ 547 $ 173 $ 272 $ 385 $ 186 $ 94 $ 86 __________ (a) Included in Depreciation and amortization in the Registrants' Consolidated Statements of Operations and Comprehensive Income. (b) Included in Operating revenues or Purchased power and fuel expense in the Registrants’ Consolidated Statements of Operations and Comprehensive Income. (c) Included in Purchased power and fuel expense in the Registrants’ Consolidated Statements of Operations and Comprehensive Income. (d) Included in Operating and maintenance expense in the Registrants’ Consolidated Statements of Operations and Comprehensive Income. Other non-cash operating activities Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE Six Months Ended June 30, 2021 Pension and non-pension postretirement benefit costs $ 196 $ 56 $ 64 $ 4 $ 29 $ 24 $ 3 $ 1 $ 5 Allowance for credit losses 100 46 24 17 4 9 5 2 2 Other decommissioning-related activity (a) (636) (636) — — — — — — — Energy-related options (b) 20 20 — — — — — — — True-up adjustments to decoupling mechanisms and formula rates (c) (176) — (64) (17) (8) (88) (46) (19) (23) Long-term incentive plan 62 — — — — — — — — Amortization of operating ROU asset 83 51 1 — 15 14 3 5 2 AFUDC — Equity (64) — (13) (12) (14) (25) (20) (3) (2) Six Months Ended June 30, 2020 Pension and non-pension postretirement benefit costs $ 203 $ 58 $ 57 $ 3 $ 31 $ 35 $ 7 $ 4 $ 7 Allowance for credit losses 92 13 17 29 10 22 12 8 2 Other decommissioning-related activity (a) (60) (60) — — — — — — — Energy-related options (b) 27 27 — — — — — — — True-up adjustments to decoupling mechanisms and formula rates (c) 55 — 13 (5) — 47 (2) 24 25 Long-term incentive plan (10) — — — — — — — — Amortization of operating ROU asset 112 80 1 — 15 14 3 4 2 Deferred Prosecution Agreement payments (d) 200 — 200 — — — — — — AFUDC — Equity (49) — (14) (7) (10) (17) (13) (2) (2) __________ (a) Includes the elimination of decommissioning-related activities for the Regulatory Agreement Units except for decommissioning-related impacts that were not offset for the Byron units in the second quarter of 2021, including the elimination of operating revenues, ARO accretion, ARC amortization, investment income, and income taxes related to all NDT fund activity for these units. See Note 10 — Asset Retirement Obligations of the Exelon 2020 Form 10-K for additional information regarding the accounting for nuclear decommissioning and Note 8 — Nuclear Decommissioning for additional information on the contractual offset suspension for the Byron units. (b) Includes option premiums reclassified to realized at the settlement of the underlying contracts and recorded to results of operations. (c) For ComEd, reflects the true-up adjustments in regulatory assets and liabilities associated with its distribution, energy efficiency, distributed generation, and transmission formula rates. For BGE, Pepco, and DPL, reflects the change in regulatory assets and liabilities associated with their decoupling mechanisms and transmission formula rates. For PECO and ACE, reflects the change in regulatory assets and liabilities associated with their transmission formula rates. See Note 3 — Regulatory Matters for additional information. (d) See Note 15 — Commitments and Contingencies for additional information related to the Deferred Prosecution Agreement. The following tables provide a reconciliation of cash, cash equivalents and restricted cash reported within the Registrants’ Consolidated Balance Sheets that sum to the total of the same amounts in their Consolidated Statements of Cash Flows. Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE June 30, 2021 Cash and cash equivalents $ 1,578 $ 542 $ 71 $ 376 $ 368 $ 61 $ 17 $ 17 $ 11 Restricted cash and cash equivalents 379 59 240 8 3 42 33 5 3 Restricted cash included in other long-term assets 52 — 43 — — 9 — — 9 Total cash, restricted cash, and cash equivalents $ 2,009 $ 601 $ 354 $ 384 $ 371 $ 112 $ 50 $ 22 $ 23 December 31, 2020 Cash and cash equivalents $ 663 $ 226 $ 83 $ 19 $ 144 $ 111 $ 30 $ 15 $ 17 Restricted cash and cash equivalents 438 89 279 7 1 39 35 — 3 Restricted cash included in other long-term assets 53 — 43 — — 10 — — 10 Cash, restricted cash, and cash equivalents - Held for Sale 12 12 — — — — — — — Total cash, restricted cash, and cash equivalents $ 1,166 $ 327 $ 405 $ 26 $ 145 $ 160 $ 65 $ 15 $ 30 June 30, 2020 Cash and cash equivalents $ 2,129 $ 483 $ 403 $ 380 $ 195 $ 39 $ 19 $ 6 $ 8 Restricted cash and cash equivalents 373 153 155 7 1 36 33 — 3 Restricted cash included in other long-term assets 178 — 166 — — 11 — — 11 Total cash, restricted cash, and cash equivalents $ 2,680 $ 636 $ 724 $ 387 $ 196 $ 86 $ 52 $ 6 $ 22 December 31, 2019 Cash and cash equivalents $ 587 $ 303 $ 90 $ 21 $ 24 $ 131 $ 30 $ 13 $ 12 Restricted cash and cash equivalents 358 146 150 6 1 36 33 — 2 Restricted cash included in other long-term assets 177 — 163 — — 14 — — 14 Total cash, restricted cash, and cash equivalents $ 1,122 $ 449 $ 403 $ 27 $ 25 $ 181 $ 63 $ 13 $ 28 For additional information on restricted cash see Note 1 — Significant Accounting Policies of the Exelon 2020 Form 10-K.
Supplemental Balance Sheet Disclosures	The following tables provide additional information about material items recorded in the Registrants' Consolidated Balance Sheets. Accrued expenses Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE June 30, 2021 Compensation-related accruals (a) $ 730 $ 255 $ 136 $ 51 $ 55 $ 85 $ 28 $ 16 $ 13 Taxes accrued 473 242 77 31 35 86 58 9 9 Interest accrued 339 43 116 40 45 51 27 8 12 December 31, 2020 Compensation-related accruals (a) $ 1,069 $ 426 $ 170 $ 73 $ 84 $ 109 $ 36 $ 18 $ 17 Taxes accrued 527 229 94 16 73 117 90 18 12 Interest accrued 331 44 109 37 46 51 26 7 12 __________ (a) Primarily includes accrued payroll, bonuses and other incentives, vacation and benefits.

Related Party Transactions (Tab

Related Party Transactions (Tables)	6 Months Ended
Related Party Transactions (Tables)	Jun. 30, 2021
Related Party Transactions [Abstract]
Operating Revenues and Purchased Power and Fuel	The following table presents Generation’s Operating revenues from affiliates, which are primarily recorded as Purchased power from affiliates and an immaterial amount recorded as Operating and maintenance expense from affiliates at the Utility Registrants: Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 Operating revenues from affiliates: ComEd (a)(b) $ 75 $ 80 $ 153 $ 170 PECO (c) 41 41 83 78 BGE (d) 58 70 130 169 PHI 77 78 176 182 Pepco (e) 55 60 130 139 DPL (f) 17 16 37 38 ACE (g) 5 2 9 5 Other 3 2 7 2 Total operating revenues from affiliates (Generation) $ 254 $ 271 $ 549 $ 601 __________ (a) Generation has an ICC-approved RFP contract with ComEd to provide a portion of ComEd’s electricity supply requirements. Generation also sells RECs and ZECs to ComEd. (b) For the three and six months ended June 30, 2021, respectively, ComEd’s Purchased power from Generation of $78 million and $163 million is recorded as Operating revenues from ComEd of $75 million and $153 million and as Purchased power and fuel from ComEd of $3 million and $10 million at Generation. For the three and six months ended June 30, 2020 , respectively, ComEd’s Purchased power from Generation of $84 million and $181 million is recorded as Operating revenues from ComEd of $80 million and $170 million and as Purchased power and fuel from ComEd of $4 million and $11 million at Generation. (c) Generation provides electric supply to PECO under contracts executed through PECO’s competitive procurement process. In addition, Generation has a ten-year agreement with PECO to sell solar AECs. (d) Generation provides a portion of BGE’s energy requirements under its MDPSC-approved market-based SOS and gas commodity programs. (e) Generation provides electric supply to Pepco under contracts executed through Pepco's competitive procurement process approved by the MDPSC and DCPSC. (f) Generation provides a portion of DPL's energy requirements under its MDPSC and DPSC-approved market-based SOS commodity programs. (g) Generation provides electric supply to ACE under contracts executed through ACE's competitive procurement process.
BSC and PHISCO Service Companies	The following table presents the service company costs allocated to the Registrants: Operating and maintenance from affiliates Capitalized costs Three Months Ended June 30, Six Months Ended June 30, Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 2021 2020 2021 2020 Exelon BSC $ 124 $ 129 $ 282 $ 242 PHISCO 17 16 36 30 Generation BSC $ 135 $ 133 $ 280 $ 273 10 14 33 25 ComEd BSC 72 67 143 138 45 41 102 83 PECO BSC 40 36 80 73 17 18 44 33 BGE BSC 45 40 88 82 20 30 43 58 PHI BSC 37 35 76 72 32 26 60 43 PHISCO — — — — 17 16 36 30 Pepco BSC 23 20 45 41 13 9 25 15 PHISCO 28 32 57 62 7 7 15 13 DPL BSC 15 13 29 26 10 9 19 14 PHISCO 24 25 49 49 5 5 11 9 ACE BSC 12 11 24 21 8 8 15 12 PHISCO 21 23 43 44 5 4 10 8
Current Receivables From/Payables To Affiliates	The following tables present current receivables from affiliates and current payables to affiliates: June 30, 2021 Receivables from affiliates: Payables to affiliates: Generation ComEd PECO BGE Pepco DPL ACE BSC PHISCO Other Total Generation $ 20 $ — $ — $ — $ — $ — $ 84 $ — $ 15 $ 119 ComEd $ 52 (a) — — — — — 50 — 7 109 PECO 22 — — — — — 24 — 4 50 BGE 8 — — — — — 31 — 2 41 PHI — — — — — — — 4 — 10 14 Pepco 12 — — — — — 14 14 2 42 DPL 3 — — — — — 9 10 1 23 ACE 12 — — — — — 8 10 — 30 Other 8 2 — — — — 1 — — 11 Total $ 117 $ 22 $ — $ — $ — $ — $ 1 $ 224 $ 34 $ 41 $ 439 December 31, 2020 Receivables from affiliates: Payables to affiliates: Generation ComEd PECO BGE Pepco DPL ACE BSC PHISCO Other Total Generation $ 13 $ — $ — $ — $ — $ — $ 72 $ — $ 22 $ 107 ComEd $ 78 (a) — — — — — 59 — 9 146 PECO 17 1 — — — — 28 — 4 50 BGE 11 — — — — — 47 — 3 61 PHI — — — — — — — 4 — 11 15 Pepco 13 2 — 1 — — 25 14 — 55 DPL 3 1 — — — — 21 10 1 36 ACE 6 — — — — — 15 9 1 31 Other 25 5 2 2 2 1 6 — — 43 Total $ 153 $ 22 $ 2 $ 3 $ 2 $ 1 $ 6 $ 271 $ 33 $ 51 $ 544 __________ (a) As of June 30, 2021 and December 31, 2020, Generation had a contract liability with ComEd for $7 million and $50 million, respectively, that was included in Other current liabilities on Generation’s Consolidated Balance Sheets. At June 30, 2021 and December 31, 2020, ComEd had a Current Payable to Generation of $45 million and $28 million, respectively, on its Consolidated Balance Sheets, which consisted of Generation’s Current Receivable from ComEd, partially offset by Generation’s contract liability with ComEd.
Noncurrent Receivables from/Payables to affiliates	The following table presents noncurrent receivables from affiliates at ComEd and PECO which are recorded as noncurrent payables to affiliates at Generation: June 30, 2021 December 31, 2020 ComEd $ 2,439 $ 2,541 PECO 571 475
Long Term Debt to Financing Trusts	The following table presents Long-term debt to financing trusts: June 30, 2021 December 31, 2020 Exelon ComEd PECO Exelon ComEd PECO ComEd Financing III $ 206 $ 205 $ — $ 206 $ 205 $ — PECO Trust III 81 — 81 81 — 81 PECO Trust IV 103 — 103 103 — 103 Total $ 390 $ 205 $ 184 $ 390 $ 205 $ 184

Mergers, Acquisitions, and Di_2

Mergers, Acquisitions, and Dispositions - Narrative (Details) $ in Millions	Apr. 01, 2014USD ($)	Jun. 30, 2021USD ($)MW	Jun. 30, 2020USD ($)	Dec. 31, 2020
Business Dispositions
Gain (Loss) on Sale of Assets and Asset Impairment Charges		$ 83	$ 13
CENG [Member]
Business Acquisitions
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners		49.99%
Solar Business
Business Dispositions
Capacity Of Facility Of Company Owned Solar Distribution Generation Facilities \| MW		360
Disposal Group, Including Discontinued Operation, Consideration		$ 810
Proceeds from Divestiture of Businesses		675
Disposal Group, Including Discontinued Operation, Liabilities, Noncurrent		125
Gain (Loss) on Sale of Assets and Asset Impairment Charges		68
Albany Green Energy biomass facility
Business Dispositions
Disposal Group, Including Discontinued Operation, Consideration		36
Impairment of Long-Lived Assets to be Disposed of		140
Exelon Generation Co L L C [Member]
Business Dispositions
Gain (Loss) on Sale of Assets and Asset Impairment Charges		$ 79	$ 12
Exelon Generation Co L L C [Member] \| CENG [Member]
Business Acquisitions
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners		49.99%
Exelon Generation Co L L C [Member] \| Solar Business
Business Dispositions
Capacity Of Facility Of Company Owned Solar Distribution Generation Facilities \| MW		360
Disposal Group, Including Discontinued Operation, Consideration		$ 810
Proceeds from Divestiture of Businesses		675
Disposal Group, Including Discontinued Operation, Liabilities, Noncurrent		125
Gain (Loss) on Sale of Assets and Asset Impairment Charges		68
Exelon Generation Co L L C [Member] \| Albany Green Energy biomass facility
Business Dispositions
Disposal Group, Including Discontinued Operation, Consideration		36
Impairment of Long-Lived Assets to be Disposed of		$ 140
CENG [Member]
Business Acquisitions
Equity Method Investment, Ownership Percentage		50.01%		50.01%
Payments of Capital Distribution	$ 400
Due from Affiliates	400	$ 645
CENG Preferred Distribution Return		8.50%
CENG [Member] \| Nine Mile Point
Business Acquisitions
Equity Method Investment, Ownership Percentage		82.00%
CENG [Member] \| Exelon Generation Co L L C [Member]
Business Acquisitions
Equity Method Investment, Ownership Percentage		50.01%		50.01%
Payments of Capital Distribution	400
Due from Affiliates	$ 400	$ 645
CENG Preferred Distribution Return		8.50%
CENG [Member] \| Exelon Generation Co L L C [Member] \| Nine Mile Point
Business Acquisitions
Equity Method Investment, Ownership Percentage		82.00%

Regulatory Matters - Narrative

Regulatory Matters - Narrative (Details) - USD ($)	Jul. 15, 2021	Feb. 15, 2021	Jun. 30, 2021	Jun. 15, 2021	Aug. 26, 2020
Texas-based generating assets
Regulatory Matters Additional Narrative Information [Line Items]
Operating and maintenance			$ 880,000,000
Market Payment Shortfall in Collections			17,000,000
Exelon Generation Co L L C [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Public Utilities, Approved Return on Equity, Percentage	9.33%
Exelon Generation Co L L C [Member] \| ERCOT
Regulatory Matters Additional Narrative Information [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amount		$ 9,000
Market Payment Shortfall in Collections			3,000,000,000
Market-wide Limit Recovery of Default			2,500,000
Exelon Generation Co L L C [Member] \| Texas-based generating assets
Regulatory Matters Additional Narrative Information [Line Items]
Operating and maintenance			880,000,000
Market Payment Shortfall in Collections			17,000,000
Commonwealth Edison Co [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Increase (Decrease) in Regulatory Assets			116,000,000
Commonwealth Edison Co [Member] \| Electric Distribution Formula Rate Annual Reconciliations [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Increase (Decrease) in Regulatory Assets			67,000,000
Commonwealth Edison Co [Member] \| Energy Efficiency Costs [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Increase (Decrease) in Regulatory Assets			85,000,000
Commonwealth Edison Co [Member] \| Renewable energy swaps
Regulatory Matters Additional Narrative Information [Line Items]
Increase (Decrease) in Regulatory Assets			36,000,000
PECO Energy Co [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Increase (Decrease) in Regulatory Assets			95,000,000
Increase (Decrease) in Regulatory Liabilities			85,000,000
PECO Energy Co [Member] \| Nuclear Decommissioning [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Increase (Decrease) in Regulatory Liabilities			96,000,000
PECO Energy Co [Member] \| Electric Energy and Natural Gas Cost [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Increase (Decrease) in Regulatory Liabilities			(13,000,000)
PECO Energy Co [Member] \| Deferred Income Tax Charge [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Increase (Decrease) in Regulatory Assets			81,000,000
PECO Energy Co [Member] \| Vacation Accrual
Regulatory Matters Additional Narrative Information [Line Items]
Increase (Decrease) in Regulatory Assets			12,000,000
Baltimore Gas and Electric Company [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Maryland Relief Act Funds				$ 50,000,000
Increase (Decrease) in Regulatory Liabilities			(109,000,000)
Baltimore Gas and Electric Company [Member] \| Deferred Income Tax Charge [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Increase (Decrease) in Regulatory Liabilities			(111,000,000)
Potomac Electric Power Company [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Maryland Relief Act Funds				12,000,000
Increase (Decrease) in Regulatory Liabilities			(53,000,000)
Potomac Electric Power Company [Member] \| Deferred Income Tax Charge [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Increase (Decrease) in Regulatory Liabilities			(46,000,000)
Potomac Electric Power Company [Member] \| Electric Transmission Formula Rate Annual Reconciliations [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Increase (Decrease) in Regulatory Liabilities			(14,000,000)
Potomac Electric Power Company [Member] \| District of Columbia 2019 Electric Distribution Base Rate Case [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Increase (Decrease) in Regulatory Liabilities			10,000,000
Delmarva Power and Light Company [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Maryland Relief Act Funds				$ 8,000,000
Increase (Decrease) in Regulatory Liabilities			(32,000,000)
Delmarva Power and Light Company [Member] \| Deferred Income Tax Charge [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Increase (Decrease) in Regulatory Liabilities			(26,000,000)
Delmarva Power and Light Company [Member] \| Electric Transmission Formula Rate Annual Reconciliations [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Increase (Decrease) in Regulatory Liabilities			(9,000,000)
Atlantic City Electric Company [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Proposed Capital Expenditure					$ 220,000,000
Increase (Decrease) in Regulatory Liabilities			(27,000,000)
Atlantic City Electric Company [Member] \| Deferred Income Tax Charge [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Increase (Decrease) in Regulatory Liabilities			(20,000,000)
Atlantic City Electric Company [Member] \| Electric Transmission Formula Rate Annual Reconciliations [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Increase (Decrease) in Regulatory Liabilities			$ (6,000,000)

Regulatory Matters - Schedule o

Regulatory Matters - Schedule of Completed Rate Cases (Details) - USD ($) $ in Millions

Jul. 14, 2021

Jun. 28, 2021

Jun. 22, 2021

Jun. 08, 2021

Mar. 31, 2021

Feb. 26, 2021

Dec. 16, 2020

Dec. 09, 2020

Sep. 30, 2020

Sep. 11, 2020

Jun. 01, 2020

Apr. 16, 2020

Commonwealth Edison Co [Member] | Illinois 2020 Electric Distribution Base Rate Case [Member]

Regulatory Matters Completed Rate Cases [Line Items]

Requested Revenue Requirement Increase (Decrease)

$ (11)

Approved Revenue Requirement Increase (Decrease)

$ (14)

Approved Return on Equity, Percentage

8.38%

Public Utilities Requested Rate Increase (Decrease), Prior Year Annual Reconciliation

$ (64)

Public Utilities, Approved Equity Capital Structure, Percentage

6.28%

Basis points for ComEd's Revenue Requirement

580

Commonwealth Edison Co [Member] | Illinois 2020 Electric Distribution Base Rate Case [Member] | 2021

Regulatory Matters Completed Rate Cases [Line Items]

Approved Revenue Requirement Increase (Decrease)

$ 50

PECO Energy Co [Member] | Pennsylvania 2020 Natural Gas Distribution Base Rate Case

Regulatory Matters Completed Rate Cases [Line Items]

Requested Revenue Requirement Increase (Decrease)

$ 69

Approved Revenue Requirement Increase (Decrease)

$ 29

Approved Return on Equity, Percentage

10.24%

Baltimore Gas and Electric Company [Member] | Maryland 2020 Electric Distribution Base Rate Case [Member]

Regulatory Matters Completed Rate Cases [Line Items]

Public Utilities, Requested Rate Increase (Decrease), Amended, Amount

$ 203

Approved Revenue Requirement Increase (Decrease)

$ 140

Approved Return on Equity, Percentage

9.50%

Baltimore Gas and Electric Company [Member] | Maryland 2020 Electric Distribution Base Rate Case [Member] | 2021

Regulatory Matters Completed Rate Cases [Line Items]

Approved Revenue Requirement Increase (Decrease)

$ 59

Baltimore Gas and Electric Company [Member] | Maryland 2020 Electric Distribution Base Rate Case [Member] | 2022

Regulatory Matters Completed Rate Cases [Line Items]

Approved Revenue Requirement Increase (Decrease)

Baltimore Gas and Electric Company [Member] | Maryland 2020 Electric Distribution Base Rate Case [Member] | 2023

Regulatory Matters Completed Rate Cases [Line Items]

Approved Revenue Requirement Increase (Decrease)

Baltimore Gas and Electric Company [Member] | Maryland 2020 Gas Distribution Base Rate Case [Member]

Regulatory Matters Completed Rate Cases [Line Items]

Public Utilities, Requested Rate Increase (Decrease), Amended, Amount

$ 108

Approved Revenue Requirement Increase (Decrease)

$ 74

Approved Return on Equity, Percentage

9.65%

Baltimore Gas and Electric Company [Member] | Maryland 2020 Gas Distribution Base Rate Case [Member] | 2021

Regulatory Matters Completed Rate Cases [Line Items]

Approved Revenue Requirement Increase (Decrease)

$ 53

Baltimore Gas and Electric Company [Member] | Maryland 2020 Gas Distribution Base Rate Case [Member] | 2022

Regulatory Matters Completed Rate Cases [Line Items]

Approved Revenue Requirement Increase (Decrease)

Baltimore Gas and Electric Company [Member] | Maryland 2020 Gas Distribution Base Rate Case [Member] | 2023

Regulatory Matters Completed Rate Cases [Line Items]

Approved Revenue Requirement Increase (Decrease)

$ 10

Potomac Electric Power Company [Member] | Maryland 2020 Electric Distribution Base Rate Case [Member]

Regulatory Matters Completed Rate Cases [Line Items]

Public Utilities, Requested Rate Increase (Decrease), Amended, Amount

$ 104

Approved Revenue Requirement Increase (Decrease)

$ 52

Approved Return on Equity, Percentage

9.55%

Potomac Electric Power Company [Member] | Maryland 2020 Electric Distribution Base Rate Case [Member] | March 31, 2022

Regulatory Matters Completed Rate Cases [Line Items]

Approved Revenue Requirement Increase (Decrease)

$ 21

Potomac Electric Power Company [Member] | Maryland 2020 Electric Distribution Base Rate Case [Member] | March 31, 2023

Regulatory Matters Completed Rate Cases [Line Items]

Approved Revenue Requirement Increase (Decrease)

Potomac Electric Power Company [Member] | Maryland 2020 Electric Distribution Base Rate Case [Member] | March 31, 2024

Regulatory Matters Completed Rate Cases [Line Items]

Approved Revenue Requirement Increase (Decrease)

$ 15

Potomac Electric Power Company [Member] | District of Columbia 2019 Electric Distribution Base Rate Case [Member]

Regulatory Matters Completed Rate Cases [Line Items]

Public Utilities, Requested Rate Increase (Decrease), Amended, Amount

$ 136

Approved Revenue Requirement Increase (Decrease)

$ 109

Approved Return on Equity, Percentage

9.275%

Potomac Electric Power Company [Member] | District of Columbia 2019 Electric Distribution Base Rate Case [Member] | 2021

Regulatory Matters Completed Rate Cases [Line Items]

Approved Revenue Requirement Increase (Decrease)

$ 42

Potomac Electric Power Company [Member] | District of Columbia 2019 Electric Distribution Base Rate Case [Member] | 2021 | Offsets

Regulatory Matters Completed Rate Cases [Line Items]

Approved Revenue Requirement Increase (Decrease)

(22)

Potomac Electric Power Company [Member] | District of Columbia 2019 Electric Distribution Base Rate Case [Member] | 2022

Regulatory Matters Completed Rate Cases [Line Items]

Approved Revenue Requirement Increase (Decrease)

Potomac Electric Power Company [Member] | District of Columbia 2019 Electric Distribution Base Rate Case [Member] | 2022 | Offsets

Regulatory Matters Completed Rate Cases [Line Items]

Approved Revenue Requirement Increase (Decrease)

$ (40)

Atlantic City Electric Company [Member] | New Jersey 2020 Electric Distribution Base Rate Case

Regulatory Matters Completed Rate Cases [Line Items]

Public Utilities, Requested Rate Increase (Decrease), Amended, Amount

$ 67

Approved Revenue Requirement Increase (Decrease)

$ 41

Approved Return on Equity, Percentage

9.60%

Atlantic City Electric Company [Member] | New Jersey 2020 Electric Distribution Base Rate Case | Tax Benefits

Regulatory Matters Completed Rate Cases [Line Items]

Approved Revenue Requirement Increase (Decrease)

$ 11

Regulatory Matters - Schedule_2

Regulatory Matters - Schedule of Pending Rate Cases (Details) - USD ($) $ in Millions	Apr. 16, 2021	Mar. 30, 2021	Feb. 02, 2021
Commonwealth Edison Co [Member] \| Illinois 2021 Electric Distribution Base Rate Case
Regulatory Matters Pending Rate Cases [Line Items]
Requested Revenue Requirement Increase (Decrease)	$ 51
Requested Return on Equity, Percentage	7.36%
Public Utilities, Requested Rate Increase (Decrease), Initial Revenue Requirement, Amount	$ 40
Public Utilities Requested Rate Increase (Decrease), Prior Year Annual Reconciliation	$ 11
Requested Return on Distribution Rate Base, Percentage	5.72%
Basis points for ComEd's Revenue Requirement	580
Commonwealth Edison Co [Member] \| Illinois 2021 Electric Distribution Base Rate Case 2020 Reconciliation
Regulatory Matters Pending Rate Cases [Line Items]
Requested Return on Equity, Percentage	7.29%
Requested Return on Distribution Rate Base, Percentage	5.69%
Basis points for ComEd's Revenue Requirement	580
Commonwealth Edison Co [Member] \| Illinois 2021 Electric Distribution Base Rate Case 2020 Reconciliation \| Performance Metrics Penalty
Regulatory Matters Pending Rate Cases [Line Items]
Basis points for ComEd's Revenue Requirement	7
PECO Energy Co [Member] \| Pennsylvania 2021 Electric Distribution Base Rate Case
Regulatory Matters Pending Rate Cases [Line Items]
Requested Revenue Requirement Increase (Decrease)		$ 246
Requested Return on Equity, Percentage		10.95%
Delmarva Power and Light Company [Member] \| Delaware 2020 Electric Distribution Base Rate Case [Member]
Regulatory Matters Pending Rate Cases [Line Items]
Requested Revenue Requirement Increase (Decrease), Amended			$ 23
Requested Return on Equity, Percentage			10.30%

Regulatory Matters - Annual Ele

Regulatory Matters - Annual Electric Transmission Fillings (Details) - 2021 Transmission Formula Rate Annual Update [Domain] - USD ($) $ in Millions	May 28, 2021	May 14, 2021	May 10, 2021	Apr. 16, 2021
Commonwealth Edison Co [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amount				$ 33
Annual Reconciliation Increase				12
Public Utilities, Requested Rate Increase (Decrease), Amended, Amount				$ 45
Public Utilities, Approved Equity Capital Structure, Percentage				8.20%
Public Utilities, Approved Return on Equity, Percentage				11.50%
Cap on Equity Component of Rate of Return on Common Equity in Federal Energy Regulatory Committee Complaint				55.00%
PECO Energy Co [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amount	$ (2)
Annual Reconciliation Increase	26
Public Utilities, Requested Rate Increase (Decrease), Amended, Amount	$ 24
Public Utilities, Approved Equity Capital Structure, Percentage	7.37%
Public Utilities, Approved Return on Equity, Percentage	10.35%
Cap on Equity Component of Rate of Return on Common Equity in Federal Energy Regulatory Committee Complaint	55.75%
Baltimore Gas and Electric Company [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amount			$ 38
Annual Reconciliation Increase			27
Public Utilities, Requested Rate Increase (Decrease), Amended, Amount			$ 65
Public Utilities, Approved Equity Capital Structure, Percentage			7.35%
Public Utilities, Approved Return on Equity, Percentage			10.50%
Potomac Electric Power Company [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amount		$ (9)
Annual Reconciliation Increase		21
Public Utilities, Requested Rate Increase (Decrease), Amended, Amount		$ 12
Public Utilities, Approved Equity Capital Structure, Percentage		7.68%
Public Utilities, Approved Return on Equity, Percentage		10.50%
Delmarva Power and Light Company [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amount		$ 19
Annual Reconciliation Increase		33
Public Utilities, Requested Rate Increase (Decrease), Amended, Amount		$ 52
Public Utilities, Approved Equity Capital Structure, Percentage		7.20%
Public Utilities, Approved Return on Equity, Percentage		10.50%
Atlantic City Electric Company [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amount		$ 27
Annual Reconciliation Increase		24
Public Utilities, Requested Rate Increase (Decrease), Amended, Amount		$ 51
Public Utilities, Approved Equity Capital Structure, Percentage		7.45%
Public Utilities, Approved Return on Equity, Percentage		10.50%

Regulatory Matters - Energy Eff

Regulatory Matters - Energy Efficiency Formula Rate (Details) - ComEd 2020 Energy Efficiency Formula Rate [Domain] - Commonwealth Edison Co [Member] - USD ($) $ in Millions	Jun. 01, 2021	Dec. 31, 2020
Schedule of Energy Efficiency Formula Rate Updates [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amount	$ 55
Revenue	(1)
Public Utilities, Requested Rate Increase (Decrease), Amended, Amount	$ 54
Public Utilities, Requested Equity Capital Structure, Percentage	5.72%
Requested Return on Equity, Percentage	7.36%
Basis points for ComEd's Revenue Requirement	580
Public Utilities, Approved Equity Capital Structure, Percentage		6.26%
Public Utilities, Approved Return on Equity, Percentage		8.46%

Regulatory Matters - Capitalize

Regulatory Matters - Capitalized Ratemaking Amount Not Recognized (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Public Utility, Property, Plant and Equipment [Line Items]
Public Utilities, Amount of Allowance for Earnings on Equity Capitalized for Rate Making Purposes	$ 48	$ 51
Commonwealth Edison Co [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Public Utilities, Amount of Allowance for Earnings on Equity Capitalized for Rate Making Purposes	1	(1)
PECO Energy Co [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Public Utilities, Amount of Allowance for Earnings on Equity Capitalized for Rate Making Purposes	0	0
Baltimore Gas and Electric Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Public Utilities, Amount of Allowance for Earnings on Equity Capitalized for Rate Making Purposes	41	45
Pepco Holdings LLC [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Public Utilities, Amount of Allowance for Earnings on Equity Capitalized for Rate Making Purposes	6	7
Potomac Electric Power Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Public Utilities, Amount of Allowance for Earnings on Equity Capitalized for Rate Making Purposes	3	4
Delmarva Power and Light Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Public Utilities, Amount of Allowance for Earnings on Equity Capitalized for Rate Making Purposes	3	3
Atlantic City Electric Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Public Utilities, Amount of Allowance for Earnings on Equity Capitalized for Rate Making Purposes	$ 0	$ 0

Revenue from Contracts with C_3

Revenue from Contracts with Customers - Change in Contract with Customer, Asset and Liability (Details) - USD ($) $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2021	Jun. 30, 2020
Contract Asset [Roll Forward]
Beginning Balance - Contract Assets	$ 153	$ 144	$ 172	$ 174	$ 144	$ 174
Consideration (received) due, contract assets	(12)	(16)	(26)	(19)
Revenues recognized, contract assets	9	13	13	17
Contract with Customer, Asset, Increase (Decrease) for Contract Acquired in Business Combination		12
Ending Balance - Contract Assets	150	153	159	172	150	159
Contract Liabilities [Roll Forward]
Beginning Balance - Contract Liabilities	147	151	29	33	151	33
Consideration received (due), contract liabilities	17	20	13	20
Revenues recognized, contract liabilities	(32)	(27)	(22)	(24)
Contract with Customer, Liability, Increase (Decrease) for Contract Acquired in Business Combination		3
Ending Balance - Contract Liabilities	132	147	20	29	132	20
Contract with Customer, Performance Obligation Satisfied in Previous Period	17		14		34	23
Exelon Generation Co L L C [Member]
Contract Asset [Roll Forward]
Beginning Balance - Contract Assets	153	144	172	174	144	174
Consideration (received) due, contract assets	(12)	(16)	(26)	(19)
Revenues recognized, contract assets	9	13	13	17
Contract with Customer, Asset, Increase (Decrease) for Contract Acquired in Business Combination		12
Ending Balance - Contract Assets	150	153	159	172	150	159
Contract Liabilities [Roll Forward]
Beginning Balance - Contract Liabilities	54	84	56	71	84	71
Consideration received (due), contract liabilities	39	31	34	55
Revenues recognized, contract liabilities	(68)	(64)	(63)	(70)
Contract with Customer, Liability, Increase (Decrease) for Contract Acquired in Business Combination		3
Ending Balance - Contract Liabilities	25	54	27	56	25	27
Contract with Customer, Performance Obligation Satisfied in Previous Period	41		42		79	61
Pepco Holdings LLC [Member]
Contract Liabilities [Roll Forward]
Beginning Balance - Contract Liabilities	116	118	0	0	118	0
Consideration received (due), contract liabilities	0	0	0	0
Revenues recognized, contract liabilities	(3)	(2)	0	0
Contract with Customer, Liability, Increase (Decrease) for Contract Acquired in Business Combination		0
Ending Balance - Contract Liabilities	113	116	0	0	113	0
Contract with Customer, Performance Obligation Satisfied in Previous Period	3		0		5	0
Potomac Electric Power Company [Member]
Contract Liabilities [Roll Forward]
Beginning Balance - Contract Liabilities	92	94	0	0	94	0
Consideration received (due), contract liabilities	0	0	0	0
Revenues recognized, contract liabilities	(1)	(2)	0	0
Contract with Customer, Liability, Increase (Decrease) for Contract Acquired in Business Combination		0
Ending Balance - Contract Liabilities	91	92	0	0	91	0
Contract with Customer, Performance Obligation Satisfied in Previous Period	1		0		3	0
Delmarva Power and Light Company [Member]
Contract Liabilities [Roll Forward]
Beginning Balance - Contract Liabilities	12	12	0	0	12	0
Consideration received (due), contract liabilities	0	0	0	0
Revenues recognized, contract liabilities	(1)	0	0	0
Contract with Customer, Liability, Increase (Decrease) for Contract Acquired in Business Combination		0
Ending Balance - Contract Liabilities	11	12	0	0	11	0
Contract with Customer, Performance Obligation Satisfied in Previous Period	1		0		1	0
Atlantic City Electric Company [Member]
Contract Liabilities [Roll Forward]
Beginning Balance - Contract Liabilities	12	12	0	0	12	0
Consideration received (due), contract liabilities	0	0	0	0
Revenues recognized, contract liabilities	(1)	0	0	0
Contract with Customer, Liability, Increase (Decrease) for Contract Acquired in Business Combination		0
Ending Balance - Contract Liabilities	11	$ 12	0	$ 0	11	0
Contract with Customer, Performance Obligation Satisfied in Previous Period	$ 1		$ 0		$ 1	$ 0

Revenue from Contracts with C_4

Revenue from Contracts with Customers - Performance Obligations (Details) $ in Millions	Jun. 30, 2021USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 506
Exelon Generation Co L L C [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	546
Pepco Holdings LLC [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	113
Potomac Electric Power Company [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	91
Delmarva Power and Light Company [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	11
Atlantic City Electric Company [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	11
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-07-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 149
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	6 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-07-01 \| Exelon Generation Co L L C [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 223
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	6 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-07-01 \| Pepco Holdings LLC [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 5
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	6 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-07-01 \| Potomac Electric Power Company [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 3
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	6 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-07-01 \| Delmarva Power and Light Company [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 1
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	6 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-07-01 \| Atlantic City Electric Company [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 1
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	6 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 100
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01 \| Exelon Generation Co L L C [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 146
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01 \| Pepco Holdings LLC [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 8
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01 \| Potomac Electric Power Company [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 6
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01 \| Delmarva Power and Light Company [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 1
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01 \| Atlantic City Electric Company [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 1
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 46
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01 \| Exelon Generation Co L L C [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 54
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01 \| Pepco Holdings LLC [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 8
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01 \| Potomac Electric Power Company [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 6
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01 \| Delmarva Power and Light Company [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 1
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01 \| Atlantic City Electric Company [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 1
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 31
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01 \| Exelon Generation Co L L C [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 29
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01 \| Pepco Holdings LLC [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 6
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01 \| Potomac Electric Power Company [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 5
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01 \| Delmarva Power and Light Company [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 0
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01 \| Atlantic City Electric Company [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 1
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2025-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 180
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2025-01-01 \| Exelon Generation Co L L C [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 94
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2025-01-01 \| Pepco Holdings LLC [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 86
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2025-01-01 \| Potomac Electric Power Company [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 71
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2025-01-01 \| Delmarva Power and Light Company [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 8
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2025-01-01 \| Atlantic City Electric Company [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 7
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year

Segment Information - Narrative

Segment Information - Narrative (Details)	6 Months Ended
Segment Information - Narrative (Details)	Jun. 30, 2021Reportable_segment
Segment Reporting Information [Line Items]
Number of reportable segments	11
Exelon Generation Co L L C [Member]
Segment Reporting Information [Line Items]
Number of reportable segments	5
Pepco Holdings LLC [Member]
Segment Reporting Information [Line Items]
Number of reportable segments	3

Segment Information - Reconcili

Segment Information - Reconciliation to Consolidated Financial Statements (Details) - USD ($) $ in Millions		3 Months Ended				6 Months Ended
		Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Segment Reporting Information [Line Items]
Revenues		$ 7,915		$ 7,322		$ 17,805	$ 16,069
Revenue from Related Parties		0		1		0	2
Depreciation and Amortization		1,666		1,001		3,363	2,023
Operating Expenses		7,561		6,769		17,643	14,298
Interest expense, net		396		427		783	837
Income (Loss) before income taxes		551		794		268	879
Income taxes		74		219		55	(75)
Net income (loss)		476	$ (264)	574	$ 376	211	950
Capital expenditures		1,900		1,757		4,040	3,773
Assets	[1]	129,396				129,396		$ 129,317
Exelon Generation Co L L C [Member]
Segment Reporting Information [Line Items]
Revenues		4,153		3,880		9,712	8,613
Revenue from Related Parties		254		271		549	601
Income (Loss) before income taxes		124		860		(823)	313
Income taxes		110		329		(70)	(59)
Net income (loss)		13	(769)	529	(161)	(756)	368
Capital expenditures						719	930
Assets	[2]	45,821				45,821		48,094
Pepco Holdings LLC [Member]
Segment Reporting Information [Line Items]
Revenues		1,140		1,016		2,384	2,187
Revenue from Related Parties		4		3		7	7
Income (Loss) before income taxes		138		7		273	126
Income taxes		(3)		(87)		5	(76)
Net income (loss)		141	$ 128	94	$ 108	269	202
Capital expenditures						889	686
Assets	[3]	24,235				24,235		23,736
Commonwealth Edison Co Affiliate [Member] \| Exelon Generation Co L L C [Member]
Segment Reporting Information [Line Items]
Revenue from Related Parties		75		80		153	170
PECO Energy Co Affiliate [Member] \| Exelon Generation Co L L C [Member]
Segment Reporting Information [Line Items]
Revenue from Related Parties		41		41		83	78
Baltimore Gas And Electric Company Affiliate [Member] \| Exelon Generation Co L L C [Member]
Segment Reporting Information [Line Items]
Revenue from Related Parties		58		70		130	169
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues		(794)		(760)		(1,594)	(1,587)
Revenue from Related Parties		(794)		(760)		(1,594)	(1,585)
Depreciation and Amortization		0		0		0	0
Operating Expenses		(768)		(748)		(1,549)	(1,564)
Interest expense, net		0		0		0	0
Income (Loss) before income taxes		0		1		1	2
Income taxes		0		0		0	0
Net income (loss)		0		1		1	2
Capital expenditures		0		0		0	0
Assets		(10,168)				(10,168)		(10,165)
Intersegment Eliminations [Member] \| Pepco Holdings LLC [Member]
Segment Reporting Information [Line Items]
Revenues		(95)		(98)		(190)	(190)
Revenue from Related Parties		(95)		(98)		(190)	(190)
Depreciation and Amortization		0		0		0	0
Operating Expenses		(95)		(98)		(190)	(190)
Interest expense, net		0		0		0	0
Income (Loss) before income taxes		0		0		0	0
Income taxes		0		0		0	0
Net income (loss)		0		0		0	0
Capital expenditures		0		0		0	0
Assets		(69)				(69)		(33)
Exelon Generation Co L L C [Member] \| Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenues		4,153		3,880		9,712	8,613
Depreciation and Amortization		930		300		1,869	604
Operating Expenses		4,469		3,547		11,141	7,947
Interest expense, net		76		87		148	197
Income (Loss) before income taxes		124		860		(823)	313
Income taxes		110		329		(70)	(59)
Net income (loss)		13		529		(756)	368
Capital expenditures		337		372		719	930
Assets		45,821				45,821		48,094
Exelon Generation Co L L C [Member] \| Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenue from Related Parties		254		271		549	601
Commonwealth Edison Co [Member] \| Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenues		1,517		1,417		3,052	2,856
Depreciation and Amortization		296		274		589	547
Operating Expenses		1,196		1,345		2,406	2,497
Interest expense, net		98		98		193	192
Income (Loss) before income taxes		238		(15)		475	189
Income taxes		46		46		85	82
Net income (loss)		192		(61)		390	107
Capital expenditures		549		523		1,162	1,029
Assets		35,324				35,324		34,466
Commonwealth Edison Co [Member] \| Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenue from Related Parties		5		11		11	16
PECO Energy Co [Member] \| Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenues		693		681		1,582	1,493
Depreciation and Amortization		87		88		173	173
Operating Expenses		552		618		1,231	1,242
Interest expense, net		42		36		80	71
Income (Loss) before income taxes		106		32		283	187
Income taxes		2		(7)		12	9
Net income (loss)		104		39		271	178
Capital expenditures		282		253		577	512
Assets		13,491				13,491		12,531
PECO Energy Co [Member] \| Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenue from Related Parties		2		2		4	4
Baltimore Gas and Electric Company [Member] \| Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenues		682		616		1,656	1,554
Depreciation and Amortization		141		129		293	272
Operating Expenses		620		573		1,372	1,263
Interest expense, net		34		32		67	64
Income (Loss) before income taxes		37		17		233	237
Income taxes		(8)		(22)		(21)	18
Net income (loss)		45		39		254	219
Capital expenditures		284		265		620	548
Assets		12,186				12,186		11,650
Baltimore Gas and Electric Company [Member] \| Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenue from Related Parties		7		4		13	10
Pepco Holdings LLC [Member] \| Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenues		1,140		1,016		2,384	2,187
Depreciation and Amortization		194		191		404	385
Operating Expenses		955		956		2,013	1,955
Interest expense, net		67		67		134	134
Income (Loss) before income taxes		138		7		273	126
Income taxes		(3)		(87)		5	(76)
Net income (loss)		141		94		269	202
Capital expenditures		433		310		889	686
Assets		24,235				24,235		23,736
Pepco Holdings LLC [Member] \| Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenue from Related Parties		4		3		7	7
Potomac Electric Power Company [Member] \| Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenues		523		494		1,076	1,039
Depreciation and Amortization		96		92		199	186
Operating Expenses		429		436		895	899
Interest expense, net		35		34		69	68
Income (Loss) before income taxes		72		33		137	90
Income taxes		(3)		(24)		3	(19)
Net income (loss)		75		57		134	109
Capital expenditures		219		144		439	324
Assets		9,588				9,588		9,264
Potomac Electric Power Company [Member] \| Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenue from Related Parties		1		1		3	3
Delmarva Power and Light Company [Member] \| Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenues		298		267		680	617
Depreciation and Amortization		51		47		104	94
Operating Expenses		255		263		564	547
Interest expense, net		16		15		30	31
Income (Loss) before income taxes		31		(9)		92	44
Income taxes		1		(28)		6	(20)
Net income (loss)		30		19		86	64
Capital expenditures		99		89		211	184
Assets		5,229				5,229		5,140
Delmarva Power and Light Company [Member] \| Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenue from Related Parties		2		2		4	4
Atlantic City Electric Company [Member] \| Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenues		319		256		629	532
Depreciation and Amortization		40		44		87	86
Operating Expenses		269		258		552	509
Interest expense, net		14		15		29	29
Income (Loss) before income taxes		36		(15)		50	(1)
Income taxes		(1)		(33)		(1)	(32)
Net income (loss)		37		18		51	31
Capital expenditures		116		77		239	178
Assets		4,473				4,473		4,286
Atlantic City Electric Company [Member] \| Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenue from Related Parties		1		1		1	1
Corporate and Other [Member] \| Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Revenues		524		472		1,013	953
Depreciation and Amortization		18		19		35	42
Operating Expenses		537		478		1,029	958
Interest expense, net		79		107		161	179
Income (Loss) before income taxes		(92)		(108)		(174)	(175)
Income taxes		(73)		(40)		44	(49)
Net income (loss)		(19)		(67)		(218)	(126)
Capital expenditures		15		34		73	68
Assets		8,507				8,507		9,005
Corporate and Other [Member] \| Corporate, Non-Segment [Member] \| Pepco Holdings LLC [Member]
Segment Reporting Information [Line Items]
Revenues		95		97		189	189
Depreciation and Amortization		7		8		14	19
Operating Expenses		97		97		192	190
Interest expense, net		2		3		6	6
Income (Loss) before income taxes		(1)		(2)		(6)	(7)
Income taxes		0		(2)		(3)	(5)
Net income (loss)		(1)		0		(2)	(2)
Capital expenditures		(1)		0		0	0
Assets		5,014				5,014		$ 5,079
Corporate and Other [Member] \| Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenue from Related Parties		522		470		1,010	949
Corporate and Other [Member] \| Intersegment Eliminations [Member] \| Pepco Holdings LLC [Member]
Segment Reporting Information [Line Items]
Revenue from Related Parties		95		97		189	189
Competitive businesses electric revenues [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		3,497		3,146		7,389	6,571
Competitive businesses electric revenues [Member] \| Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		(250)		(268)		(546)	(594)
Competitive businesses electric revenues [Member] \| Exelon Generation Co L L C [Member] \| Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		3,747		3,414		7,935	7,165
Competitive businesses electric revenues [Member] \| Commonwealth Edison Co [Member] \| Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		0		0		0	0
Competitive businesses electric revenues [Member] \| PECO Energy Co [Member] \| Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		0		0		0	0
Competitive businesses electric revenues [Member] \| Baltimore Gas and Electric Company [Member] \| Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		0		0		0	0
Competitive businesses electric revenues [Member] \| Pepco Holdings LLC [Member] \| Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		0		0		0	0
Competitive businesses electric revenues [Member] \| Corporate and Other [Member] \| Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		0		0		0	0
Competitive businesses natural gas revenues Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		507		353		1,833	1,022
Competitive businesses natural gas revenues Member] \| Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		0		0		0	(3)
Competitive businesses natural gas revenues Member] \| Exelon Generation Co L L C [Member] \| Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		507		353		1,833	1,025
Competitive businesses natural gas revenues Member] \| Commonwealth Edison Co [Member] \| Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		0		0		0	0
Competitive businesses natural gas revenues Member] \| PECO Energy Co [Member] \| Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		0		0		0	0
Competitive businesses natural gas revenues Member] \| Baltimore Gas and Electric Company [Member] \| Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		0		0		0	0
Competitive businesses natural gas revenues Member] \| Pepco Holdings LLC [Member] \| Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		0		0		0	0
Competitive businesses natural gas revenues Member] \| Corporate and Other [Member] \| Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		0		0		0	0
Competitive businesses other revenues [Member]
Segment Reporting Information [Line Items]
Competitive businesses other revenues		(104)		112		(57)	421
Competitive businesses other revenues [Member] \| Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Competitive businesses other revenues		(3)		(1)		(1)	(2)
Competitive businesses other revenues [Member] \| Exelon Generation Co L L C [Member] \| Operating Segment [Member]
Segment Reporting Information [Line Items]
Competitive businesses other revenues		(101)		113		(56)	423
Competitive businesses other revenues [Member] \| Commonwealth Edison Co [Member] \| Operating Segment [Member]
Segment Reporting Information [Line Items]
Competitive businesses other revenues		0		0		0	0
Competitive businesses other revenues [Member] \| PECO Energy Co [Member] \| Operating Segment [Member]
Segment Reporting Information [Line Items]
Competitive businesses other revenues		0		0		0	0
Competitive businesses other revenues [Member] \| Baltimore Gas and Electric Company [Member] \| Operating Segment [Member]
Segment Reporting Information [Line Items]
Competitive businesses other revenues		0		0		0	0
Competitive businesses other revenues [Member] \| Pepco Holdings LLC [Member] \| Operating Segment [Member]
Segment Reporting Information [Line Items]
Competitive businesses other revenues		0		0		0	0
Competitive businesses other revenues [Member] \| Corporate and Other [Member] \| Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Competitive businesses other revenues		0		0		0	0
Rate-regulated electric revenues [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		3,787		3,475		7,775	7,222
Rate-regulated electric revenues [Member] \| Pepco Holdings LLC [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		1,071		1,047		2,195	2,133
Rate-regulated electric revenues [Member] \| Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		(11)		(15)		(21)	(27)
Rate-regulated electric revenues [Member] \| Intersegment Eliminations [Member] \| Pepco Holdings LLC [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		(3)		(4)		(7)	(8)
Rate-regulated electric revenues [Member] \| Exelon Generation Co L L C [Member] \| Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		0		0		0	0
Rate-regulated electric revenues [Member] \| Commonwealth Edison Co [Member] \| Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		1,517		1,417		3,052	2,856
Rate-regulated electric revenues [Member] \| PECO Energy Co [Member] \| Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		610		586		1,271	1,189
Rate-regulated electric revenues [Member] \| Baltimore Gas and Electric Company [Member] \| Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		558		504		1,190	1,118
Rate-regulated electric revenues [Member] \| Pepco Holdings LLC [Member] \| Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		1,113		983		2,283	2,086
Rate-regulated electric revenues [Member] \| Potomac Electric Power Company [Member] \| Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		523		494		1,076	1,039
Rate-regulated electric revenues [Member] \| Delmarva Power and Light Company [Member] \| Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		274		237		585	523
Rate-regulated electric revenues [Member] \| Atlantic City Electric Company [Member] \| Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		319		256		629	532
Rate-regulated electric revenues [Member] \| Corporate and Other [Member] \| Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		0		0		0	0
Rate-regulated electric revenues [Member] \| Corporate and Other [Member] \| Corporate, Non-Segment [Member] \| Pepco Holdings LLC [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		0		0		0	0
Rate-regulated natural gas revenues [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		228		236		865	832
Rate-regulated natural gas revenues [Member] \| Pepco Holdings LLC [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		24		30		94	94
Rate-regulated natural gas revenues [Member] \| Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		(3)		(1)		(7)	(2)
Rate-regulated natural gas revenues [Member] \| Intersegment Eliminations [Member] \| Pepco Holdings LLC [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		0		0		0	0
Rate-regulated natural gas revenues [Member] \| Exelon Generation Co L L C [Member] \| Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		0		0		0	0
Rate-regulated natural gas revenues [Member] \| Commonwealth Edison Co [Member] \| Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		0		0		0	0
Rate-regulated natural gas revenues [Member] \| PECO Energy Co [Member] \| Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		83		95		311	304
Rate-regulated natural gas revenues [Member] \| Baltimore Gas and Electric Company [Member] \| Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		124		112		466	436
Rate-regulated natural gas revenues [Member] \| Pepco Holdings LLC [Member] \| Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		24		30		95	94
Rate-regulated natural gas revenues [Member] \| Potomac Electric Power Company [Member] \| Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		0		0		0	0
Rate-regulated natural gas revenues [Member] \| Delmarva Power and Light Company [Member] \| Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		24		30		95	94
Rate-regulated natural gas revenues [Member] \| Atlantic City Electric Company [Member] \| Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		0		0		0	0
Rate-regulated natural gas revenues [Member] \| Corporate and Other [Member] \| Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		0		0		0	0
Rate-regulated natural gas revenues [Member] \| Corporate and Other [Member] \| Corporate, Non-Segment [Member] \| Pepco Holdings LLC [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		0		0		0	0
Shared service and other revenues [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		0		0		0	1
Shared service and other revenues [Member] \| Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		(527)		(475)		(1,019)	(959)
Shared service and other revenues [Member] \| Intersegment Eliminations [Member] \| Pepco Holdings LLC [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		(92)		(94)		(183)	(182)
Shared service and other revenues [Member] \| Exelon Generation Co L L C [Member] \| Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		0		0		0	0
Shared service and other revenues [Member] \| Commonwealth Edison Co [Member] \| Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		0		0		0	0
Shared service and other revenues [Member] \| PECO Energy Co [Member] \| Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		0		0		0	0
Shared service and other revenues [Member] \| Baltimore Gas and Electric Company [Member] \| Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		0		0		0	0
Shared service and other revenues [Member] \| Pepco Holdings LLC [Member] \| Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		3		3		6	7
Shared service and other revenues [Member] \| Potomac Electric Power Company [Member] \| Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		0		0		0	0
Shared service and other revenues [Member] \| Delmarva Power and Light Company [Member] \| Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		0		0		0	0
Shared service and other revenues [Member] \| Atlantic City Electric Company [Member] \| Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		0		0		0	0
Shared service and other revenues [Member] \| Corporate and Other [Member] \| Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		524		472		1,013	953
Shared service and other revenues [Member] \| Corporate and Other [Member] \| Corporate, Non-Segment [Member] \| Pepco Holdings LLC [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		$ 95		$ 97		$ 189	$ 189

[1]	Exelon’s consolidated assets include $10,093 million and $10,200 million at June 30, 2021 and December 31, 2020, respectively, of certain VIEs that can only be used to settle the liabilities of the VIE. Exelon’s consolidated liabilities include $3,578 million and $3,598 million at June 30, 2021 and December 31, 2020, respectively, of certain VIEs for which the VIE creditors do not have recourse to Exelon. See Note 17 — Variable Interest Entities for additional information.
[2]	Generation’s consolidated assets include $10,077 million and $10,182 million at June 30, 2021 and December 31, 2020, respectively, of certain VIEs that can only be used to settle the liabilities of the VIE. Generation’s consolidated liabilities include $3,563 million and $3,572 million at June 30, 2021 and December 31, 2020, respectively, of certain VIEs for which the VIE creditors do not have recourse to Generation. See Note 17 — Variable Interest Entities for additional information.
[3]	PHI’s consolidated total assets include $16 million and $18 million at June 30, 2021 and December 31, 2020, respectively, of PHI's consolidated VIE that can only be used to settle the liabilities of the VIE. PHI’s consolidated total liabilities include $15 million and $26 million at June 30, 2021 and December 31, 2020, respectively, of PHI's consolidated VIE for which the VIE creditors do not have recourse to PHI. See Note 17 — Variable Interest Entities for additional information.

Segment Information - Generatio

Segment Information - Generation Total Revenues (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Segment Reporting Information [Line Items]
Revenues	$ 7,915	$ 7,322	$ 17,805	$ 16,069
Revenue from Related Parties	0	1	0	2
Generation Mid Atlantic [Member]
Segment Reporting Information [Line Items]
Revenues	1,091	1,074	2,255	2,247
Generation Midwest [Member]
Segment Reporting Information [Line Items]
Revenues	962	962	1,960	1,964
Generation New York [Member]
Segment Reporting Information [Line Items]
Revenues	381	340	719	655
Generation ERCOT [Member]
Segment Reporting Information [Line Items]
Revenues	275	234	532	424
Generation Other Regions [Member]
Segment Reporting Information [Line Items]
Revenues	1,038	804	2,469	1,875
Generation Reportable Segments Total [Member]
Segment Reporting Information [Line Items]
Revenues	3,747	3,414	7,935	7,165
Generation Natural Gas [Member]
Segment Reporting Information [Line Items]
Revenues	507	353	1,833	1,025
Generation All Other Segments [Member]
Segment Reporting Information [Line Items]
Revenues	(101)	113	(56)	423
Unrealized Gain (Loss) on Securities	(239)	21	(323)	200
Generation Total Consolidated Group [Member]
Segment Reporting Information [Line Items]
Revenues	4,153	3,880	9,712	8,613
Operating Segment [Member] \| Generation Mid Atlantic [Member]
Segment Reporting Information [Line Items]
Revenues	1,086	1,065	2,244	2,232
Operating Segment [Member] \| Generation Midwest [Member]
Segment Reporting Information [Line Items]
Revenues	962	962	1,959	1,970
Operating Segment [Member] \| Generation New York [Member]
Segment Reporting Information [Line Items]
Revenues	381	341	719	656
Operating Segment [Member] \| Generation ERCOT [Member]
Segment Reporting Information [Line Items]
Revenues	271	227	523	411
Operating Segment [Member] \| Generation Other Regions [Member]
Segment Reporting Information [Line Items]
Revenues	1,047	819	2,490	1,896
Operating Segment [Member] \| Generation Reportable Segments Total [Member]
Segment Reporting Information [Line Items]
Revenues	3,747	3,414	7,935	7,165
Operating Segment [Member] \| Generation Natural Gas [Member]
Segment Reporting Information [Line Items]
Revenues	507	353	1,833	1,025
Operating Segment [Member] \| Generation All Other Segments [Member]
Segment Reporting Information [Line Items]
Unrealized Gain (Loss) on Securities	314	85	489	218
Operating Segment [Member] \| Generation Total Consolidated Group [Member]
Segment Reporting Information [Line Items]
Revenues	4,153	3,880	9,712	8,613
Corporate, Non-Segment [Member] \| Generation All Other Segments [Member]
Segment Reporting Information [Line Items]
Revenues	(101)	113	(56)	423
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues	(794)	(760)	(1,594)	(1,587)
Revenue from Related Parties	(794)	(760)	(1,594)	(1,585)
Intersegment Eliminations [Member] \| Generation Mid Atlantic [Member]
Segment Reporting Information [Line Items]
Revenue from Related Parties	5	9	11	15
Intersegment Eliminations [Member] \| Generation Midwest [Member]
Segment Reporting Information [Line Items]
Revenue from Related Parties	0	0	1	(6)
Intersegment Eliminations [Member] \| Generation New York [Member]
Segment Reporting Information [Line Items]
Revenue from Related Parties	0	(1)	0	(1)
Intersegment Eliminations [Member] \| Generation ERCOT [Member]
Segment Reporting Information [Line Items]
Revenue from Related Parties	4	7	9	13
Intersegment Eliminations [Member] \| Generation Other Regions [Member]
Segment Reporting Information [Line Items]
Revenue from Related Parties	(9)	(15)	(21)	(21)
Intersegment Eliminations [Member] \| Generation Reportable Segments Total [Member]
Segment Reporting Information [Line Items]
Revenue from Related Parties	0	0	0	0
Intersegment Eliminations [Member] \| Generation Natural Gas [Member]
Segment Reporting Information [Line Items]
Revenue from Related Parties	0	0	0	0
Intersegment Eliminations [Member] \| Generation All Other Segments [Member]
Segment Reporting Information [Line Items]
Revenue from Related Parties	0	0	0	0
Intersegment Eliminations [Member] \| Generation Total Consolidated Group [Member]
Segment Reporting Information [Line Items]
Revenue from Related Parties	0	0	0	0
Revenue from Contract with Customer [Member] \| Operating Segment [Member] \| Generation Mid Atlantic [Member]
Segment Reporting Information [Line Items]
Revenues	1,062	1,100	2,233	2,365
Revenue from Contract with Customer [Member] \| Operating Segment [Member] \| Generation Midwest [Member]
Segment Reporting Information [Line Items]
Revenues	975	855	1,983	1,798
Revenue from Contract with Customer [Member] \| Operating Segment [Member] \| Generation New York [Member]
Segment Reporting Information [Line Items]
Revenues	376	336	759	672
Revenue from Contract with Customer [Member] \| Operating Segment [Member] \| Generation ERCOT [Member]
Segment Reporting Information [Line Items]
Revenues	179	175	533	330
Revenue from Contract with Customer [Member] \| Operating Segment [Member] \| Generation Other Regions [Member]
Segment Reporting Information [Line Items]
Revenues	921	776	2,095	1,782
Revenue from Contract with Customer [Member] \| Operating Segment [Member] \| Generation Reportable Segments Total [Member]
Segment Reporting Information [Line Items]
Revenues	3,513	3,242	7,603	6,947
Revenue from Contract with Customer [Member] \| Operating Segment [Member] \| Generation Natural Gas [Member]
Segment Reporting Information [Line Items]
Revenues	253	209	1,117	712
Revenue from Contract with Customer [Member] \| Operating Segment [Member] \| Generation Total Consolidated Group [Member]
Segment Reporting Information [Line Items]
Revenues	3,873	3,537	8,915	7,844
Revenue from Contract with Customer [Member] \| Corporate, Non-Segment [Member] \| Generation All Other Segments [Member]
Segment Reporting Information [Line Items]
Revenues	107	86	195	185
Other [Member] \| Operating Segment [Member] \| Generation Mid Atlantic [Member]
Segment Reporting Information [Line Items]
Revenues	24	(35)	11	(133)
Other [Member] \| Operating Segment [Member] \| Generation Midwest [Member]
Segment Reporting Information [Line Items]
Revenues	(13)	107	(24)	172
Other [Member] \| Operating Segment [Member] \| Generation New York [Member]
Segment Reporting Information [Line Items]
Revenues	5	5	(40)	(16)
Other [Member] \| Operating Segment [Member] \| Generation ERCOT [Member]
Segment Reporting Information [Line Items]
Revenues	92	52	(10)	81
Other [Member] \| Operating Segment [Member] \| Generation Other Regions [Member]
Segment Reporting Information [Line Items]
Revenues	126	43	395	114
Other [Member] \| Operating Segment [Member] \| Generation Reportable Segments Total [Member]
Segment Reporting Information [Line Items]
Revenues	234	172	332	218
Other [Member] \| Operating Segment [Member] \| Generation Natural Gas [Member]
Segment Reporting Information [Line Items]
Revenues	254	144	716	313
Other [Member] \| Operating Segment [Member] \| Generation Total Consolidated Group [Member]
Segment Reporting Information [Line Items]
Revenues	280	343	797	769
Other [Member] \| Corporate, Non-Segment [Member] \| Generation All Other Segments [Member]
Segment Reporting Information [Line Items]
Revenues	$ (208)	$ 27	$ (251)	$ 238

Segment Information - Generat_2

Segment Information - Generation Total Revenues Net of Purchased Power and Fuel Expense (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Generation Mid Atlantic [Member]
Segment Reporting Information [Line Items]
Revenue Net of Purchase Power And Fuel	$ 572	$ 525	$ 1,141	$ 1,092
Generation Midwest [Member]
Segment Reporting Information [Line Items]
Revenue Net of Purchase Power And Fuel	658	703	1,360	1,427
Generation New York [Member]
Segment Reporting Information [Line Items]
Revenue Net of Purchase Power And Fuel	292	246	536	440
Generation ERCOT [Member]
Segment Reporting Information [Line Items]
Revenue Net of Purchase Power And Fuel	83	97	(1,102)	177
Generation Other Regions [Member]
Segment Reporting Information [Line Items]
Revenue Net of Purchase Power And Fuel	136	157	353	312
Generation Reportable Segments Total [Member]
Segment Reporting Information [Line Items]
Revenue Net of Purchase Power And Fuel	1,741	1,728	2,288	3,448
Generation All Other Segments [Member]
Segment Reporting Information [Line Items]
Revenue Net of Purchase Power And Fuel	465	210	867	519
Unrealized Gain (Loss) on Securities	(239)	21	(323)	200
Generation Total Consolidated Group [Member]
Segment Reporting Information [Line Items]
Revenue Net of Purchase Power And Fuel	2,206	1,938	3,155	3,967
Operating Segment [Member] \| Generation Mid Atlantic [Member]
Segment Reporting Information [Line Items]
RNF from external customers	567	516	1,130	1,074
Operating Segment [Member] \| Generation Midwest [Member]
Segment Reporting Information [Line Items]
RNF from external customers	658	702	1,359	1,431
Operating Segment [Member] \| Generation New York [Member]
Segment Reporting Information [Line Items]
RNF from external customers	289	243	531	433
Operating Segment [Member] \| Generation ERCOT [Member]
Segment Reporting Information [Line Items]
RNF from external customers	80	92	(957)	168
Operating Segment [Member] \| Generation Other Regions [Member]
Segment Reporting Information [Line Items]
RNF from external customers	157	181	409	355
Operating Segment [Member] \| Generation Reportable Segments Total [Member]
Segment Reporting Information [Line Items]
RNF from external customers	1,751	1,734	2,472	3,461
Operating Segment [Member] \| Generation All Other Segments [Member]
Segment Reporting Information [Line Items]
RNF from external customers	455	204	683	506
Unrealized Gain (Loss) on Securities	314	85	489	218
Accelerated nuclear fuel amortization			106
Operating Segment [Member] \| Generation Total Consolidated Group [Member]
Segment Reporting Information [Line Items]
RNF from external customers	2,206	1,938	3,155	3,967
Intersegment Eliminations [Member] \| Generation Mid Atlantic [Member]
Segment Reporting Information [Line Items]
Intersegment Revenue Net Of Purchase Power And Fuel	5	9	11	18
Intersegment Eliminations [Member] \| Generation Midwest [Member]
Segment Reporting Information [Line Items]
Intersegment Revenue Net Of Purchase Power And Fuel	0	1	1	(4)
Intersegment Eliminations [Member] \| Generation New York [Member]
Segment Reporting Information [Line Items]
Intersegment Revenue Net Of Purchase Power And Fuel	3	3	5	7
Intersegment Eliminations [Member] \| Generation ERCOT [Member]
Segment Reporting Information [Line Items]
Intersegment Revenue Net Of Purchase Power And Fuel	3	5	(145)	9
Intersegment Eliminations [Member] \| Generation Other Regions [Member]
Segment Reporting Information [Line Items]
Intersegment Revenue Net Of Purchase Power And Fuel	(21)	(24)	(56)	(43)
Intersegment Eliminations [Member] \| Generation Reportable Segments Total [Member]
Segment Reporting Information [Line Items]
Intersegment Revenue Net Of Purchase Power And Fuel	(10)	(6)	(184)	(13)
Intersegment Eliminations [Member] \| Generation All Other Segments [Member]
Segment Reporting Information [Line Items]
Intersegment Revenue Net Of Purchase Power And Fuel	10	6	184	13
Intersegment Eliminations [Member] \| Generation Total Consolidated Group [Member]
Segment Reporting Information [Line Items]
Intersegment Revenue Net Of Purchase Power And Fuel	$ 0	$ 0	$ 0	$ 0

Segment Information - Electric

Segment Information - Electric and Gas Revenue by Customer Class (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Revenue, Major Customer [Line Items]
Revenues	$ 7,915,000,000	$ 7,322,000,000	$ 17,805,000,000	$ 16,069,000,000
Revenue from Related Parties	0	1,000,000	0	2,000,000
Commonwealth Edison Co [Member]
Revenue, Major Customer [Line Items]
Revenues	1,517,000,000	1,417,000,000	3,052,000,000	2,856,000,000
Revenue from Related Parties	5,000,000	11,000,000	11,000,000	16,000,000
Commonwealth Edison Co [Member] \| Regulated Operation [Member]
Revenue, Major Customer [Line Items]
Revenues	1,499,000,000	1,442,000,000	2,972,000,000	2,863,000,000
Commonwealth Edison Co [Member] \| Other Regulated Revenue [Member]
Revenue, Major Customer [Line Items]
Revenues	18,000,000	(25,000,000)	80,000,000	(7,000,000)
PECO Energy Co [Member]
Revenue, Major Customer [Line Items]
Revenues	693,000,000	681,000,000	1,582,000,000	1,493,000,000
Revenue from Related Parties	2,000,000	2,000,000	4,000,000	4,000,000
PECO Energy Co [Member] \| Regulated Operation [Member]
Revenue, Major Customer [Line Items]
Revenues	686,000,000	678,000,000	1,565,000,000	1,485,000,000
PECO Energy Co [Member] \| Other Regulated Revenue [Member]
Revenue, Major Customer [Line Items]
Revenues	7,000,000	3,000,000	17,000,000	8,000,000
Baltimore Gas and Electric Company [Member]
Revenue, Major Customer [Line Items]
Revenues	682,000,000	616,000,000	1,656,000,000	1,554,000,000
Revenue from Related Parties	7,000,000	4,000,000	13,000,000	10,000,000
Baltimore Gas and Electric Company [Member] \| Regulated Operation [Member]
Revenue, Major Customer [Line Items]
Revenues	688,000,000	652,000,000	1,644,000,000	1,550,000,000
Baltimore Gas and Electric Company [Member] \| Other Regulated Revenue [Member]
Revenue, Major Customer [Line Items]
Revenues	(6,000,000)	(36,000,000)	12,000,000	4,000,000
Pepco Holdings LLC [Member]
Revenue, Major Customer [Line Items]
Revenues	1,140,000,000	1,016,000,000	2,384,000,000	2,187,000,000
Revenue from Related Parties	4,000,000	3,000,000	7,000,000	7,000,000
Pepco Holdings LLC [Member] \| Regulated Operation [Member]
Revenue, Major Customer [Line Items]
Revenues	1,098,000,000	1,080,000,000	2,296,000,000	2,233,000,000
Pepco Holdings LLC [Member] \| Other Regulated Revenue [Member]
Revenue, Major Customer [Line Items]
Revenues	42,000,000	(64,000,000)	88,000,000	(46,000,000)
Potomac Electric Power Company [Member]
Revenue, Major Customer [Line Items]
Revenues	523,000,000	494,000,000	1,076,000,000	1,039,000,000
Revenue from Related Parties	1,000,000	1,000,000	3,000,000	3,000,000
Potomac Electric Power Company [Member] \| Regulated Operation [Member]
Revenue, Major Customer [Line Items]
Revenues	503,000,000	507,000,000	1,030,000,000	1,036,000,000
Potomac Electric Power Company [Member] \| Other Regulated Revenue [Member]
Revenue, Major Customer [Line Items]
Revenues	20,000,000	(13,000,000)	46,000,000	3,000,000
Delmarva Power and Light Company [Member]
Revenue, Major Customer [Line Items]
Revenues	298,000,000	267,000,000	680,000,000	617,000,000
Revenue from Related Parties	2,000,000	2,000,000	4,000,000	4,000,000
Delmarva Power and Light Company [Member] \| Regulated Operation [Member]
Revenue, Major Customer [Line Items]
Revenues	288,000,000	292,000,000	661,000,000	640,000,000
Delmarva Power and Light Company [Member] \| Other Regulated Revenue [Member]
Revenue, Major Customer [Line Items]
Revenues	10,000,000	(25,000,000)	19,000,000	(23,000,000)
Atlantic City Electric Company [Member]
Revenue, Major Customer [Line Items]
Revenues	319,000,000	256,000,000	629,000,000	532,000,000
Revenue from Related Parties	1,000,000	1,000,000	1,000,000	1,000,000
Atlantic City Electric Company [Member] \| Regulated Operation [Member]
Revenue, Major Customer [Line Items]
Revenues	307,000,000	282,000,000	606,000,000	557,000,000
Atlantic City Electric Company [Member] \| Other Regulated Revenue [Member]
Revenue, Major Customer [Line Items]
Revenues	12,000,000	(26,000,000)	23,000,000	(25,000,000)
Rate-regulated electric revenues [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	3,787,000,000	3,475,000,000	7,775,000,000	7,222,000,000
Rate-regulated electric revenues [Member] \| Commonwealth Edison Co [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	1,503,000,000	1,431,000,000	2,977,000,000	2,853,000,000
Rate-regulated electric revenues [Member] \| Commonwealth Edison Co [Member] \| Regulated Operation [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	1,499,000,000	1,442,000,000	2,972,000,000	2,863,000,000
Revenue from Related Parties	5,000,000	11,000,000	11,000,000	16,000,000
Rate-regulated electric revenues [Member] \| Commonwealth Edison Co [Member] \| Regulated Operation [Member] \| Operating Segment [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	9,000,000	0	16,000,000	6,000,000
Rate-regulated electric revenues [Member] \| Commonwealth Edison Co [Member] \| Regulated Operation [Member] \| Residential [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	759,000,000	767,000,000	1,502,000,000	1,468,000,000
Rate-regulated electric revenues [Member] \| Commonwealth Edison Co [Member] \| Regulated Operation [Member] \| Small Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	377,000,000	327,000,000	744,000,000	689,000,000
Rate-regulated electric revenues [Member] \| Commonwealth Edison Co [Member] \| Regulated Operation [Member] \| Large Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	138,000,000	119,000,000	271,000,000	253,000,000
Rate-regulated electric revenues [Member] \| Commonwealth Edison Co [Member] \| Regulated Operation [Member] \| Public Authorities & Electric Railroads [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	11,000,000	11,000,000	22,000,000	23,000,000
Rate-regulated electric revenues [Member] \| Commonwealth Edison Co [Member] \| Regulated Operation [Member] \| Other [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	214,000,000	218,000,000	433,000,000	430,000,000
Rate-regulated electric revenues [Member] \| PECO Energy Co [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	602,000,000	580,000,000	1,251,000,000	1,180,000,000
Rate-regulated electric revenues [Member] \| PECO Energy Co [Member] \| Regulated Operation [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	603,000,000	582,000,000	1,254,000,000	1,181,000,000
Revenue from Related Parties	1,000,000	1,000,000	3,000,000	3,000,000
Rate-regulated electric revenues [Member] \| PECO Energy Co [Member] \| Regulated Operation [Member] \| Operating Segment [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0	0	0	3,000,000
Rate-regulated electric revenues [Member] \| PECO Energy Co [Member] \| Regulated Operation [Member] \| Residential [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	383,000,000	377,000,000	816,000,000	759,000,000
Rate-regulated electric revenues [Member] \| PECO Energy Co [Member] \| Regulated Operation [Member] \| Small Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	99,000,000	88,000,000	199,000,000	187,000,000
Rate-regulated electric revenues [Member] \| PECO Energy Co [Member] \| Regulated Operation [Member] \| Large Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	59,000,000	55,000,000	116,000,000	108,000,000
Rate-regulated electric revenues [Member] \| PECO Energy Co [Member] \| Regulated Operation [Member] \| Public Authorities & Electric Railroads [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	8,000,000	7,000,000	17,000,000	14,000,000
Rate-regulated electric revenues [Member] \| PECO Energy Co [Member] \| Regulated Operation [Member] \| Other [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	54,000,000	55,000,000	106,000,000	113,000,000
Rate-regulated electric revenues [Member] \| Baltimore Gas and Electric Company [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	560,000,000	530,000,000	1,180,000,000	1,125,000,000
Rate-regulated electric revenues [Member] \| Baltimore Gas and Electric Company [Member] \| Regulated Operation [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	561,000,000	532,000,000	1,182,000,000	1,128,000,000
Revenue from Related Parties	4,000,000	3,000,000	5,000,000	6,000,000
Rate-regulated electric revenues [Member] \| Baltimore Gas and Electric Company [Member] \| Regulated Operation [Member] \| Operating Segment [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	3,000,000	1,000,000	3,000,000	3,000,000
Rate-regulated electric revenues [Member] \| Baltimore Gas and Electric Company [Member] \| Regulated Operation [Member] \| Residential [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	299,000,000	304,000,000	662,000,000	644,000,000
Rate-regulated electric revenues [Member] \| Baltimore Gas and Electric Company [Member] \| Regulated Operation [Member] \| Small Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	60,000,000	51,000,000	129,000,000	118,000,000
Rate-regulated electric revenues [Member] \| Baltimore Gas and Electric Company [Member] \| Regulated Operation [Member] \| Large Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	108,000,000	94,000,000	213,000,000	198,000,000
Rate-regulated electric revenues [Member] \| Baltimore Gas and Electric Company [Member] \| Regulated Operation [Member] \| Public Authorities & Electric Railroads [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	7,000,000	7,000,000	13,000,000	14,000,000
Rate-regulated electric revenues [Member] \| Baltimore Gas and Electric Company [Member] \| Regulated Operation [Member] \| Other [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	87,000,000	76,000,000	165,000,000	154,000,000
Rate-regulated electric revenues [Member] \| Pepco Holdings LLC [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	1,071,000,000	1,047,000,000	2,195,000,000	2,133,000,000
Rate-regulated electric revenues [Member] \| Pepco Holdings LLC [Member] \| Regulated Operation [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	1,074,000,000	1,050,000,000	2,202,000,000	2,139,000,000
Revenue from Related Parties	4,000,000	3,000,000	7,000,000	7,000,000
Rate-regulated electric revenues [Member] \| Pepco Holdings LLC [Member] \| Regulated Operation [Member] \| Operating Segment [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	1,000,000	0	0	1,000,000
Rate-regulated electric revenues [Member] \| Pepco Holdings LLC [Member] \| Regulated Operation [Member] \| Residential [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	537,000,000	529,000,000	1,142,000,000	1,062,000,000
Rate-regulated electric revenues [Member] \| Pepco Holdings LLC [Member] \| Regulated Operation [Member] \| Small Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	124,000,000	105,000,000	242,000,000	221,000,000
Rate-regulated electric revenues [Member] \| Pepco Holdings LLC [Member] \| Regulated Operation [Member] \| Large Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	257,000,000	240,000,000	505,000,000	493,000,000
Rate-regulated electric revenues [Member] \| Pepco Holdings LLC [Member] \| Regulated Operation [Member] \| Public Authorities & Electric Railroads [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	17,000,000	15,000,000	30,000,000	30,000,000
Rate-regulated electric revenues [Member] \| Pepco Holdings LLC [Member] \| Regulated Operation [Member] \| Other [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	139,000,000	161,000,000	283,000,000	333,000,000
Rate-regulated electric revenues [Member] \| Potomac Electric Power Company [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	503,000,000	506,000,000	1,027,000,000	1,034,000,000
Rate-regulated electric revenues [Member] \| Potomac Electric Power Company [Member] \| Regulated Operation [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	503,000,000	507,000,000	1,030,000,000	1,036,000,000
Revenue from Related Parties	1,000,000	1,000,000	3,000,000	3,000,000
Rate-regulated electric revenues [Member] \| Potomac Electric Power Company [Member] \| Regulated Operation [Member] \| Operating Segment [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	1,000,000	0	0	1,000,000
Rate-regulated electric revenues [Member] \| Potomac Electric Power Company [Member] \| Regulated Operation [Member] \| Residential [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	223,000,000	237,000,000	476,000,000	472,000,000
Rate-regulated electric revenues [Member] \| Potomac Electric Power Company [Member] \| Regulated Operation [Member] \| Small Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	32,000,000	29,000,000	65,000,000	65,000,000
Rate-regulated electric revenues [Member] \| Potomac Electric Power Company [Member] \| Regulated Operation [Member] \| Large Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	188,000,000	175,000,000	372,000,000	363,000,000
Rate-regulated electric revenues [Member] \| Potomac Electric Power Company [Member] \| Regulated Operation [Member] \| Public Authorities & Electric Railroads [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	10,000,000	8,000,000	16,000,000	17,000,000
Rate-regulated electric revenues [Member] \| Potomac Electric Power Company [Member] \| Regulated Operation [Member] \| Other [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	50,000,000	58,000,000	101,000,000	119,000,000
Rate-regulated electric revenues [Member] \| Delmarva Power and Light Company [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	262,000,000	260,000,000	562,000,000	543,000,000
Rate-regulated electric revenues [Member] \| Delmarva Power and Light Company [Member] \| Regulated Operation [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	264,000,000	262,000,000	566,000,000	546,000,000
Revenue from Related Parties	2,000,000	2,000,000	4,000,000	4,000,000
Rate-regulated electric revenues [Member] \| Delmarva Power and Light Company [Member] \| Regulated Operation [Member] \| Operating Segment [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0	0	0	1,000,000
Rate-regulated electric revenues [Member] \| Delmarva Power and Light Company [Member] \| Regulated Operation [Member] \| Residential [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	147,000,000	147,000,000	337,000,000	308,000,000
Rate-regulated electric revenues [Member] \| Delmarva Power and Light Company [Member] \| Regulated Operation [Member] \| Small Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	46,000,000	39,000,000	92,000,000	82,000,000
Rate-regulated electric revenues [Member] \| Delmarva Power and Light Company [Member] \| Regulated Operation [Member] \| Large Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	22,000,000	22,000,000	43,000,000	45,000,000
Rate-regulated electric revenues [Member] \| Delmarva Power and Light Company [Member] \| Regulated Operation [Member] \| Public Authorities & Electric Railroads [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	3,000,000	3,000,000	7,000,000	6,000,000
Rate-regulated electric revenues [Member] \| Delmarva Power and Light Company [Member] \| Regulated Operation [Member] \| Other [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	46,000,000	51,000,000	87,000,000	105,000,000
Rate-regulated electric revenues [Member] \| Atlantic City Electric Company [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	306,000,000	281,000,000	605,000,000	556,000,000
Rate-regulated electric revenues [Member] \| Atlantic City Electric Company [Member] \| Regulated Operation [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	307,000,000	282,000,000	606,000,000	557,000,000
Revenue from Related Parties	1,000,000	1,000,000	1,000,000
Rate-regulated electric revenues [Member] \| Atlantic City Electric Company [Member] \| Regulated Operation [Member] \| Operating Segment [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0	0	0	0
Rate-regulated electric revenues [Member] \| Atlantic City Electric Company [Member] \| Regulated Operation [Member] \| Residential [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	167,000,000	145,000,000	329,000,000	282,000,000
Rate-regulated electric revenues [Member] \| Atlantic City Electric Company [Member] \| Regulated Operation [Member] \| Small Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	46,000,000	37,000,000	85,000,000	74,000,000
Rate-regulated electric revenues [Member] \| Atlantic City Electric Company [Member] \| Regulated Operation [Member] \| Large Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	47,000,000	43,000,000	90,000,000	85,000,000
Rate-regulated electric revenues [Member] \| Atlantic City Electric Company [Member] \| Regulated Operation [Member] \| Public Authorities & Electric Railroads [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	4,000,000	4,000,000	7,000,000	7,000,000
Rate-regulated electric revenues [Member] \| Atlantic City Electric Company [Member] \| Regulated Operation [Member] \| Other [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	43,000,000	53,000,000	95,000,000	109,000,000
Rate-regulated natural gas revenues [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	228,000,000	236,000,000	865,000,000	832,000,000
Rate-regulated natural gas revenues [Member] \| Commonwealth Edison Co [Member] \| Regulated Operation [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0	0	0	0
Rate-regulated natural gas revenues [Member] \| Commonwealth Edison Co [Member] \| Regulated Operation [Member] \| Operating Segment [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0	0	0	0
Rate-regulated natural gas revenues [Member] \| Commonwealth Edison Co [Member] \| Regulated Operation [Member] \| Residential [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0	0	0	0
Rate-regulated natural gas revenues [Member] \| Commonwealth Edison Co [Member] \| Regulated Operation [Member] \| Small Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0	0	0	0
Rate-regulated natural gas revenues [Member] \| Commonwealth Edison Co [Member] \| Regulated Operation [Member] \| Large Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0	0	0	0
Rate-regulated natural gas revenues [Member] \| Commonwealth Edison Co [Member] \| Regulated Operation [Member] \| Transportation [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0	0	0	0
Rate-regulated natural gas revenues [Member] \| Commonwealth Edison Co [Member] \| Regulated Operation [Member] \| Other [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0	0	0	0
Rate-regulated natural gas revenues [Member] \| PECO Energy Co [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	82,000,000	95,000,000	310,000,000	304,000,000
Rate-regulated natural gas revenues [Member] \| PECO Energy Co [Member] \| Regulated Operation [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	83,000,000	96,000,000	311,000,000	304,000,000
Revenue from Related Parties	0	0	1,000,000
Rate-regulated natural gas revenues [Member] \| PECO Energy Co [Member] \| Regulated Operation [Member] \| Operating Segment [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0	(1,000,000)	0	0
Rate-regulated natural gas revenues [Member] \| PECO Energy Co [Member] \| Regulated Operation [Member] \| Residential [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	55,000,000	70,000,000	215,000,000	220,000,000
Rate-regulated natural gas revenues [Member] \| PECO Energy Co [Member] \| Regulated Operation [Member] \| Small Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	22,000,000	19,000,000	81,000,000	70,000,000
Rate-regulated natural gas revenues [Member] \| PECO Energy Co [Member] \| Regulated Operation [Member] \| Large Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0	0	0	0
Rate-regulated natural gas revenues [Member] \| PECO Energy Co [Member] \| Regulated Operation [Member] \| Transportation [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	5,000,000	6,000,000	12,000,000	12,000,000
Rate-regulated natural gas revenues [Member] \| PECO Energy Co [Member] \| Regulated Operation [Member] \| Other [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	1,000,000	1,000,000	3,000,000	2,000,000
Rate-regulated natural gas revenues [Member] \| Baltimore Gas and Electric Company [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	125,000,000	119,000,000	455,000,000	419,000,000
Rate-regulated natural gas revenues [Member] \| Baltimore Gas and Electric Company [Member] \| Regulated Operation [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	127,000,000	120,000,000	462,000,000	422,000,000
Revenue from Related Parties	3,000,000	1,000,000	7,000,000	4,000,000
Rate-regulated natural gas revenues [Member] \| Baltimore Gas and Electric Company [Member] \| Regulated Operation [Member] \| Operating Segment [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	1,000,000	0	1,000,000	1,000,000
Rate-regulated natural gas revenues [Member] \| Baltimore Gas and Electric Company [Member] \| Regulated Operation [Member] \| Residential [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	81,000,000	81,000,000	297,000,000	287,000,000
Rate-regulated natural gas revenues [Member] \| Baltimore Gas and Electric Company [Member] \| Regulated Operation [Member] \| Small Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	13,000,000	12,000,000	48,000,000	46,000,000
Rate-regulated natural gas revenues [Member] \| Baltimore Gas and Electric Company [Member] \| Regulated Operation [Member] \| Large Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	27,000,000	24,000,000	81,000,000	76,000,000
Rate-regulated natural gas revenues [Member] \| Baltimore Gas and Electric Company [Member] \| Regulated Operation [Member] \| Transportation [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0	0	0	0
Rate-regulated natural gas revenues [Member] \| Baltimore Gas and Electric Company [Member] \| Regulated Operation [Member] \| Other [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	6,000,000	3,000,000	36,000,000	13,000,000
Rate-regulated natural gas revenues [Member] \| Pepco Holdings LLC [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	24,000,000	30,000,000	94,000,000	94,000,000
Rate-regulated natural gas revenues [Member] \| Pepco Holdings LLC [Member] \| Regulated Operation [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	24,000,000	30,000,000	94,000,000	94,000,000
Rate-regulated natural gas revenues [Member] \| Pepco Holdings LLC [Member] \| Regulated Operation [Member] \| Operating Segment [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0	0	0	0
Rate-regulated natural gas revenues [Member] \| Pepco Holdings LLC [Member] \| Regulated Operation [Member] \| Residential [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	12,000,000	17,000,000	57,000,000	57,000,000
Rate-regulated natural gas revenues [Member] \| Pepco Holdings LLC [Member] \| Regulated Operation [Member] \| Small Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	6,000,000	8,000,000	24,000,000	25,000,000
Rate-regulated natural gas revenues [Member] \| Pepco Holdings LLC [Member] \| Regulated Operation [Member] \| Large Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	1,000,000	1,000,000	3,000,000	2,000,000
Rate-regulated natural gas revenues [Member] \| Pepco Holdings LLC [Member] \| Regulated Operation [Member] \| Transportation [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	3,000,000	3,000,000	8,000,000	7,000,000
Rate-regulated natural gas revenues [Member] \| Pepco Holdings LLC [Member] \| Regulated Operation [Member] \| Other [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	2,000,000	1,000,000	2,000,000	3,000,000
Rate-regulated natural gas revenues [Member] \| Potomac Electric Power Company [Member] \| Regulated Operation [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0	0	0	0
Rate-regulated natural gas revenues [Member] \| Potomac Electric Power Company [Member] \| Regulated Operation [Member] \| Operating Segment [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0	0	0	0
Rate-regulated natural gas revenues [Member] \| Potomac Electric Power Company [Member] \| Regulated Operation [Member] \| Residential [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0	0	0	0
Rate-regulated natural gas revenues [Member] \| Potomac Electric Power Company [Member] \| Regulated Operation [Member] \| Small Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0	0	0	0
Rate-regulated natural gas revenues [Member] \| Potomac Electric Power Company [Member] \| Regulated Operation [Member] \| Large Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0	0	0	0
Rate-regulated natural gas revenues [Member] \| Potomac Electric Power Company [Member] \| Regulated Operation [Member] \| Transportation [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0	0	0	0
Rate-regulated natural gas revenues [Member] \| Potomac Electric Power Company [Member] \| Regulated Operation [Member] \| Other [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0	0	0	0
Rate-regulated natural gas revenues [Member] \| Delmarva Power and Light Company [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	24,000,000	30,000,000	95,000,000	94,000,000
Rate-regulated natural gas revenues [Member] \| Delmarva Power and Light Company [Member] \| Regulated Operation [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	24,000,000	30,000,000	95,000,000	94,000,000
Rate-regulated natural gas revenues [Member] \| Delmarva Power and Light Company [Member] \| Regulated Operation [Member] \| Operating Segment [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0	0	0	0
Rate-regulated natural gas revenues [Member] \| Delmarva Power and Light Company [Member] \| Regulated Operation [Member] \| Residential [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	12,000,000	17,000,000	57,000,000	57,000,000
Rate-regulated natural gas revenues [Member] \| Delmarva Power and Light Company [Member] \| Regulated Operation [Member] \| Small Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	6,000,000	8,000,000	24,000,000	25,000,000
Rate-regulated natural gas revenues [Member] \| Delmarva Power and Light Company [Member] \| Regulated Operation [Member] \| Large Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	1,000,000	1,000,000	3,000,000	2,000,000
Rate-regulated natural gas revenues [Member] \| Delmarva Power and Light Company [Member] \| Regulated Operation [Member] \| Transportation [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	3,000,000	3,000,000	8,000,000	7,000,000
Rate-regulated natural gas revenues [Member] \| Delmarva Power and Light Company [Member] \| Regulated Operation [Member] \| Other [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	2,000,000	1,000,000	3,000,000	3,000,000
Rate-regulated natural gas revenues [Member] \| Atlantic City Electric Company [Member] \| Regulated Operation [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0	0	0	0
Rate-regulated natural gas revenues [Member] \| Atlantic City Electric Company [Member] \| Regulated Operation [Member] \| Operating Segment [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0	0	0	0
Rate-regulated natural gas revenues [Member] \| Atlantic City Electric Company [Member] \| Regulated Operation [Member] \| Residential [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0	0	0	0
Rate-regulated natural gas revenues [Member] \| Atlantic City Electric Company [Member] \| Regulated Operation [Member] \| Small Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0	0	0	0
Rate-regulated natural gas revenues [Member] \| Atlantic City Electric Company [Member] \| Regulated Operation [Member] \| Large Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0	0	0	0
Rate-regulated natural gas revenues [Member] \| Atlantic City Electric Company [Member] \| Regulated Operation [Member] \| Transportation [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0	0	0	0
Rate-regulated natural gas revenues [Member] \| Atlantic City Electric Company [Member] \| Regulated Operation [Member] \| Other [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0	0	0	0
Alternative revenue programs [Member] \| Commonwealth Edison Co [Member] \| Regulated Operation [Member] \| Operating Segment [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	9,000,000	(25,000,000)	64,000,000	(13,000,000)
Alternative revenue programs [Member] \| PECO Energy Co [Member] \| Regulated Operation [Member] \| Operating Segment [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	7,000,000	4,000,000	17,000,000	5,000,000
Alternative revenue programs [Member] \| Baltimore Gas and Electric Company [Member] \| Regulated Operation [Member] \| Operating Segment [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	(10,000,000)	(37,000,000)	8,000,000	0
Alternative revenue programs [Member] \| Pepco Holdings LLC [Member] \| Regulated Operation [Member] \| Operating Segment [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	41,000,000	(64,000,000)	88,000,000	(47,000,000)
Alternative revenue programs [Member] \| Potomac Electric Power Company [Member] \| Regulated Operation [Member] \| Operating Segment [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	19,000,000	(13,000,000)	46,000,000	2,000,000
Alternative revenue programs [Member] \| Delmarva Power and Light Company [Member] \| Regulated Operation [Member] \| Operating Segment [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	10,000,000	(25,000,000)	19,000,000	(24,000,000)
Alternative revenue programs [Member] \| Atlantic City Electric Company [Member] \| Regulated Operation [Member] \| Operating Segment [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	$ 12,000,000	$ (26,000,000)	$ 23,000,000	$ (25,000,000)

Accounts Receivable - Narrative

Accounts Receivable - Narrative (Details) - Sale of accounts receivable [Member] - USD ($) $ in Millions	Jun. 30, 2021	Jun. 24, 2021	May 24, 2021	Mar. 31, 2021	Feb. 17, 2021	Dec. 31, 2020	Apr. 08, 2020
Accounts, Notes, Loans and Financing Receivable [Line Items]
Derecognized receivables transferred at fair value	$ 1,274					$ 1,139	$ 1,200
Cash proceeds received	900	$ 50			$ 250	500	500
DPP consideration	374					639	650
Cash outflows returned			$ (50)
April 7, 2021
Accounts, Notes, Loans and Financing Receivable [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	750
March 29, 2024
Accounts, Notes, Loans and Financing Receivable [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	900
Cash proceeds received				$ 150
Exelon Generation Co L L C [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Derecognized receivables transferred at fair value	1,274					1,139	1,200
Cash proceeds received	900	$ 50			$ 250	500	500
DPP consideration	374					$ 639	$ 650
Cash outflows returned			$ (50)
Exelon Generation Co L L C [Member] \| April 7, 2021
Accounts, Notes, Loans and Financing Receivable [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	750
Exelon Generation Co L L C [Member] \| March 29, 2024
Accounts, Notes, Loans and Financing Receivable [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	$ 900
Cash proceeds received				$ 150

Accounts Receivable - Allowance

Accounts Receivable - Allowance for Credit Losses Rollforward (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current period provision for expected credit losses			$ (100)	$ (92)
Exelon Generation Co L L C [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current period provision for expected credit losses			(46)	(13)
Commonwealth Edison Co [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current period provision for expected credit losses			(24)	(17)
PECO Energy Co [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current period provision for expected credit losses			(17)	(29)
Baltimore Gas and Electric Company [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current period provision for expected credit losses			(4)	(10)
Pepco Holdings LLC [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current period provision for expected credit losses			(9)	(22)
Potomac Electric Power Company [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current period provision for expected credit losses			(5)	(12)
Delmarva Power and Light Company [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current period provision for expected credit losses			(2)	(8)
Atlantic City Electric Company [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current period provision for expected credit losses			(2)	(2)
Customer accounts receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	$ 442	$ 278	366	243
Current period provision for expected credit losses	(29)	51	75	106
Writeoffs, net of recoveries	18	12	46	32
Allowance change due to sale of customer accounts		56		56
Ending balance	395	261	395	261
Customer accounts receivable \| Exelon Generation Co L L C [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	65	81	32	80
Current period provision for expected credit losses	13	9	47	13
Writeoffs, net of recoveries	3	1	4	4
Allowance change due to sale of customer accounts		56		56
Ending balance	75	33	75	33
Customer accounts receivable \| Commonwealth Edison Co [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	103	71	97	59
Current period provision for expected credit losses	(9)	7	12	25
Writeoffs, net of recoveries	5	6	20	12
Ending balance	89	72	89	72
Customer accounts receivable \| PECO Energy Co [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	130	66	116	55
Current period provision for expected credit losses	(14)	10	6	28
Writeoffs, net of recoveries	5	5	11	12
Ending balance	111	71	111	71
Customer accounts receivable \| Baltimore Gas and Electric Company [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	43	18	35	12
Current period provision for expected credit losses	(14)	6	(5)	14
Writeoffs, net of recoveries	2	1	3	3
Ending balance	27	23	27	23
Customer accounts receivable \| Pepco Holdings LLC [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	101	42	86	37
Current period provision for expected credit losses	(5)	19	15	26
Writeoffs, net of recoveries	3	(1)	8	1
Ending balance	93	62	93	62
Customer accounts receivable \| Potomac Electric Power Company [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	41	15	32	13
Current period provision for expected credit losses	(1)	8	10	11
Writeoffs, net of recoveries	2	(1)	4	0
Ending balance	38	24	38	24
Customer accounts receivable \| Delmarva Power and Light Company [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	25	13	22	11
Current period provision for expected credit losses	(5)	5	1	7
Writeoffs, net of recoveries	1	0	4	0
Ending balance	19	18	19	18
Customer accounts receivable \| Atlantic City Electric Company [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	35	14	32	13
Current period provision for expected credit losses	1	6	4	8
Writeoffs, net of recoveries	0	0	0	1
Ending balance	36	20	36	20
Other receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	79	52	71	48
Current period provision for expected credit losses	(4)	12	6	20
Writeoffs, net of recoveries	3	3	5	7
Ending balance	72	61	72	61
Other receivables \| Exelon Generation Co L L C [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	0	0	0	0
Current period provision for expected credit losses	1	0	1	0
Writeoffs, net of recoveries	0	0	0	0
Ending balance	1	0	1	0
Other receivables \| Commonwealth Edison Co [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	22	22	21	20
Current period provision for expected credit losses	(3)	1	(2)	4
Writeoffs, net of recoveries	1	1	1	2
Ending balance	18	22	18	22
Other receivables \| PECO Energy Co [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	11	7	8	7
Current period provision for expected credit losses	(3)	1	1	2
Writeoffs, net of recoveries	1	1	2	2
Ending balance	7	7	7	7
Other receivables \| Baltimore Gas and Electric Company [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	9	5	9	5
Current period provision for expected credit losses	0	2	1	4
Writeoffs, net of recoveries	1	1	2	3
Ending balance	8	6	8	6
Other receivables \| Pepco Holdings LLC [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	37	18	33	16
Current period provision for expected credit losses	1	8	5	10
Writeoffs, net of recoveries	0	0	0	0
Ending balance	38	26	38	26
Other receivables \| Potomac Electric Power Company [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	15	8	13	7
Current period provision for expected credit losses	1	3	3	4
Writeoffs, net of recoveries	0	0	0	0
Ending balance	16	11	16	11
Other receivables \| Delmarva Power and Light Company [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	10	4	9	4
Current period provision for expected credit losses	(1)	3	0	3
Writeoffs, net of recoveries	0	0	0	0
Ending balance	9	7	9	7
Other receivables \| Atlantic City Electric Company [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	12	6	11	5
Current period provision for expected credit losses	1	2	2	3
Writeoffs, net of recoveries	0	0	0	0
Ending balance	$ 13	$ 8	$ 13	$ 8

Accounts Receivable - Unbilled

Accounts Receivable - Unbilled Customer Revenue (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unbilled customer revenue	$ 1,029	$ 998
Exelon Generation Co L L C [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unbilled customer revenue	329	258
Commonwealth Edison Co [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unbilled customer revenue	263	218
PECO Energy Co [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unbilled customer revenue	131	147
Baltimore Gas and Electric Company [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unbilled customer revenue	119	197
Pepco Holdings LLC [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unbilled customer revenue	187	178
Potomac Electric Power Company [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unbilled customer revenue	90	87
Delmarva Power and Light Company [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unbilled customer revenue	39	62
Atlantic City Electric Company [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unbilled customer revenue	$ 58	$ 29

Accounts Receivable - Purchases

Accounts Receivable - Purchases and Sales of Accounts Receivable (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Jun. 24, 2021	Feb. 17, 2021	Dec. 31, 2020	Apr. 08, 2020
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loss on sale receivables	$ 8	$ 15	$ 25	$ 15
Proceeds from new transfers			2,689	927
Cash collections received on deferred purchase price and reinvested in the Facility			1,809	1,102
Cash collections reinvested in the Facility			4,498	2,029
Accounts Receivable, Purchase			1,823	1,584
Accounts Receivable, Sale			92	533
Exelon Generation Co L L C [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loss on sale receivables	8	$ 15	25	15
Proceeds from new transfers			2,689	927
Cash collections received on deferred purchase price and reinvested in the Facility			1,809	1,102
Cash collections reinvested in the Facility			4,498	2,029
Accounts Receivable, Purchase			0	0
Accounts Receivable, Sale			107	779
Commonwealth Edison Co [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Purchase			485	518
Accounts Receivable, Sale			0	0
PECO Energy Co [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Purchase			507	494
Accounts Receivable, Sale			0	0
Baltimore Gas and Electric Company [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Purchase			343	333
Accounts Receivable, Sale			0	0
Pepco Holdings LLC [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Purchase			503	485
Accounts Receivable, Sale			0	0
Potomac Electric Power Company [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Purchase			310	303
Accounts Receivable, Sale			0	0
Delmarva Power and Light Company [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Purchase			103	98
Accounts Receivable, Sale			0	0
Atlantic City Electric Company [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Purchase			90	84
Accounts Receivable, Sale			0	0
Exelon Generation Co LLC Affiliate [Member] \| Commonwealth Edison Co [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Related Parties, Purchase			0	34
Exelon Generation Co LLC Affiliate [Member] \| PECO Energy Co [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Related Parties, Purchase			0	67
Exelon Generation Co LLC Affiliate [Member] \| Baltimore Gas and Electric Company [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Related Parties, Purchase			15	73
Exelon Generation Co LLC Affiliate [Member] \| Pepco Holdings LLC [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Related Parties, Purchase			0	72
Exelon Generation Co LLC Affiliate [Member] \| Potomac Electric Power Company [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Related Parties, Purchase			0	51
Exelon Generation Co LLC Affiliate [Member] \| Delmarva Power and Light Company [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Related Parties, Purchase			0	13
Exelon Generation Co LLC Affiliate [Member] \| Atlantic City Electric Company [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Related Parties, Purchase			0	8
Exelon Utility Registrants Affiliates [Member] \| Exelon Generation Co L L C [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Related Parties, Sale			15	246
Sale of accounts receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Derecognized receivables transferred at fair value	1,274		1,274				$ 1,139	$ 1,200
Cash proceeds received	900		900		$ 50	$ 250	500	500
DPP consideration	374		374				639	650
Transfer of Financial Assets Accounted for as Sales, Additional Transfers			4,647	2,032
Sale of accounts receivable [Member] \| Exelon Generation Co L L C [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Derecognized receivables transferred at fair value	1,274		1,274				1,139	1,200
Cash proceeds received	900		900		$ 50	$ 250	500	500
DPP consideration	374		374				$ 639	$ 650
Transfer of Financial Assets Accounted for as Sales, Additional Transfers			4,647	$ 2,032
Sale of Accounts Receivable_Three Months Ended Q1 2021
Accounts, Notes, Loans and Financing Receivable [Line Items]
Cash proceeds received	400		400
Sale of Accounts Receivable_Three Months Ended Q1 2021 \| Exelon Generation Co L L C [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Cash proceeds received	$ 400		$ 400

Early Plant Retirements - Narra

Early Plant Retirements - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Property, Plant and Equipment [Line Items]
Cost, Depreciation and Amortization	$ 1,666	$ 1,001	$ 3,363	$ 2,023
Exelon Generation Co L L C [Member]
Property, Plant and Equipment [Line Items]
Cost, Depreciation and Amortization	$ 930	$ 300	$ 1,869	$ 604
Salem [Member] \| Nuclear Plant [Member] \| Exelon Generation Co L L C [Member]
Property, Plant and Equipment [Line Items]
Ownership interest	42.59%		42.59%
Generation New England [Member]
Property, Plant and Equipment [Line Items]
Cost, Depreciation and Amortization	$ 21		$ 41
Generation New England [Member] \| Exelon Generation Co L L C [Member]
Property, Plant and Equipment [Line Items]
Cost, Depreciation and Amortization	21		41
Facility Closing [Member] \| Midwest Asset Group [Member]
Property, Plant and Equipment [Line Items]
Severance Costs					$ 81
Severance Liability	81		81
Facility Closing [Member] \| Midwest Asset Group [Member] \| Exelon Generation Co L L C [Member]
Property, Plant and Equipment [Line Items]
Severance Costs					$ 81
Severance Liability	$ 81		$ 81

Early Plant Retirements - Preta

Early Plant Retirements - Pretax Expense (Details) - Facility Closing [Member] - Byron Dresden - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2021
Accelerated depreciation	$ 611	$ 1,230
Accelerated nuclear fuel amortization	52	106
Operating and maintenance	2	4
Asset Retirement Obligation Contractual Offset	(166)	(391)
Restructuring and Related Cost, Incurred Cost	499	949
Exelon Generation Co L L C [Member]
Accelerated depreciation	611	1,230
Accelerated nuclear fuel amortization	52	106
Operating and maintenance	2	4
Asset Retirement Obligation Contractual Offset	(166)	(391)
Restructuring and Related Cost, Incurred Cost	$ 499	$ 949

Early Plant Retirements - Impli

Early Plant Retirements - Implications of Potential Early Plant Retirement on Balance Sheet (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Implications of Potential Early Plant Retirement [Line Items]
Materials and supplies inventory, net	$ 1,443	$ 1,425
Property, plant and equipment, net	82,120	82,584
Braidwood [Member] \| Facility Closing [Member]
Implications of Potential Early Plant Retirement [Line Items]
Materials and supplies inventory, net	82
Nuclear fuel inventory, net	196
Property, plant and equipment, net	1,380
Construction work in progress	30
Asset retirement obligation	(585)
LaSalle [Member] \| Facility Closing [Member]
Implications of Potential Early Plant Retirement [Line Items]
Materials and supplies inventory, net	105
Nuclear fuel inventory, net	244
Property, plant and equipment, net	1,610
Construction work in progress	12
Asset retirement obligation	(975)
Braidwood LaSalle [Member] \| Facility Closing [Member]
Implications of Potential Early Plant Retirement [Line Items]
Materials and supplies inventory, net	187
Nuclear fuel inventory, net	440
Property, plant and equipment, net	2,990
Construction work in progress	42
Asset retirement obligation	(1,560)
Exelon Generation Co L L C [Member]
Implications of Potential Early Plant Retirement [Line Items]
Materials and supplies inventory, net	986	978
Property, plant and equipment, net	19,837	$ 22,214
Exelon Generation Co L L C [Member] \| Braidwood [Member] \| Facility Closing [Member]
Implications of Potential Early Plant Retirement [Line Items]
Materials and supplies inventory, net	82
Nuclear fuel inventory, net	196
Property, plant and equipment, net	1,380
Construction work in progress	30
Asset retirement obligation	(585)
Exelon Generation Co L L C [Member] \| LaSalle [Member] \| Facility Closing [Member]
Implications of Potential Early Plant Retirement [Line Items]
Materials and supplies inventory, net	105
Nuclear fuel inventory, net	244
Property, plant and equipment, net	1,610
Construction work in progress	12
Asset retirement obligation	(975)
Exelon Generation Co L L C [Member] \| Braidwood LaSalle [Member] \| Facility Closing [Member]
Implications of Potential Early Plant Retirement [Line Items]
Materials and supplies inventory, net	187
Nuclear fuel inventory, net	440
Property, plant and equipment, net	2,990
Construction work in progress	42
Asset retirement obligation	$ (1,560)

Nuclear Decommissioning - Narra

Nuclear Decommissioning - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
	Jun. 30, 2021	Dec. 31, 2020
Nuclear Decommissioning Additional Narrative Information [Line Items]
Nuclear decommissioning trust funds	$ 15,400	$ 14,464
Nuclear Decommissioning [Member] \| Minimum [Member]
Nuclear Decommissioning Additional Narrative Information [Line Items]
Net increase (decrease) due to changes in, and timing of, estimated future cash flows	650
Nuclear Decommissioning [Member] \| Maximum [Member]
Nuclear Decommissioning Additional Narrative Information [Line Items]
Net increase (decrease) due to changes in, and timing of, estimated future cash flows	850
Nuclear Decommissioning Byron
Nuclear Decommissioning Additional Narrative Information [Line Items]
Decommissioning Related Activities Not Contractually Offset	53
Nuclear Decommissioning Byron \| Minimum [Member]
Nuclear Decommissioning Additional Narrative Information [Line Items]
Net increase (decrease) due to changes in, and timing of, estimated future cash flows	275
Nuclear Decommissioning Byron \| Maximum [Member]
Nuclear Decommissioning Additional Narrative Information [Line Items]
Net increase (decrease) due to changes in, and timing of, estimated future cash flows	375
Exelon Generation Co L L C [Member]
Nuclear Decommissioning Additional Narrative Information [Line Items]
Nuclear decommissioning trust funds	15,400	14,464
Exelon Generation Co L L C [Member] \| Nuclear Decommissioning [Member] \| Minimum [Member]
Nuclear Decommissioning Additional Narrative Information [Line Items]
Net increase (decrease) due to changes in, and timing of, estimated future cash flows	650
Exelon Generation Co L L C [Member] \| Nuclear Decommissioning [Member] \| Maximum [Member]
Nuclear Decommissioning Additional Narrative Information [Line Items]
Net increase (decrease) due to changes in, and timing of, estimated future cash flows	850
Exelon Generation Co L L C [Member] \| Nuclear Decommissioning Byron
Nuclear Decommissioning Additional Narrative Information [Line Items]
Decommissioning Related Activities Not Contractually Offset	53
Exelon Generation Co L L C [Member] \| Nuclear Decommissioning Byron \| Minimum [Member]
Nuclear Decommissioning Additional Narrative Information [Line Items]
Net increase (decrease) due to changes in, and timing of, estimated future cash flows	275
Exelon Generation Co L L C [Member] \| Nuclear Decommissioning Byron \| Maximum [Member]
Nuclear Decommissioning Additional Narrative Information [Line Items]
Net increase (decrease) due to changes in, and timing of, estimated future cash flows	375
Assets, Total [Member]
Nuclear Decommissioning Additional Narrative Information [Line Items]
Nuclear decommissioning trust funds	15,596	14,599
Assets, Total [Member] \| Exelon Generation Co L L C [Member]
Nuclear Decommissioning Additional Narrative Information [Line Items]
Nuclear decommissioning trust funds	15,596	14,599
Other Current Assets [Member]
Nuclear Decommissioning Additional Narrative Information [Line Items]
Nuclear decommissioning trust funds	196	134
Other Current Assets [Member] \| Exelon Generation Co L L C [Member]
Nuclear Decommissioning Additional Narrative Information [Line Items]
Nuclear decommissioning trust funds	$ 196	$ 134

Nuclear Decommissioning - Rollf

Nuclear Decommissioning - Rollforward of Nuclear Decommissioning ARO (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Accretion expense	$ 255	$ 247
Exelon Generation Co L L C [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Accretion expense	255	$ 247
Nuclear Decommissioning [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
ARO beginning balance	11,922
Accretion expense	249
Costs incurred related to decommissioning plants	(39)
ARO ending balance	12,132
Current portion of ARO	84		$ 80
Nuclear Decommissioning [Member] \| Exelon Generation Co L L C [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
ARO beginning balance	11,922
Accretion expense	249
Costs incurred related to decommissioning plants	(39)
ARO ending balance	12,132
Current portion of ARO	$ 84		$ 80

Asset Impairments - Narrative (

Asset Impairments - Narrative (Details) - USD ($) $ in Millions	3 Months Ended			6 Months Ended
	Jun. 30, 2021	Sep. 30, 2020	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Property, Plant and Equipment [Line Items]
Impairment of Long-Lived Assets Held-for-use				$ 500	$ 33
Net income (loss) attributable to noncontrolling interests	$ 75		$ 53	99	(153)
Deferred income taxes and amortization of investment tax credits				(163)	33
Exelon Generation Co L L C [Member]
Property, Plant and Equipment [Line Items]
Impairment of Long-Lived Assets Held-for-use				493	18
Net income (loss) attributable to noncontrolling interests	74		$ 53	98	(153)
Deferred income taxes and amortization of investment tax credits				(142)	$ (54)
Antelope Valley [Member]
Property, Plant and Equipment [Line Items]
Impairment of Long-Lived Assets Held-for-use				0
Antelope Valley [Member] \| Exelon Generation Co L L C [Member]
Property, Plant and Equipment [Line Items]
Impairment of Long-Lived Assets Held-for-use				0
Generation New England [Member]
Property, Plant and Equipment [Line Items]
Impairment of Long-Lived Assets Held-for-use	350	$ 500
Generation New England [Member] \| Exelon Generation Co L L C [Member]
Property, Plant and Equipment [Line Items]
Impairment of Long-Lived Assets Held-for-use	$ 350	$ 500
Midwest Asset Group [Member]
Property, Plant and Equipment [Line Items]
Impairment of Long-Lived Assets Held-for-use				0
Midwest Asset Group [Member] \| Exelon Generation Co L L C [Member]
Property, Plant and Equipment [Line Items]
Impairment of Long-Lived Assets Held-for-use				$ 0

Income Taxes - Narrative (Detai

Income Taxes - Narrative (Details) $ in Millions	Jun. 30, 2021USD ($)
State and Local Jurisdiction [Member] \| Atlantic City Electric Company [Member]
Income Tax Additional Narrative Information [Line Items]
Significant Change in Unrecognized Tax Benefits is Reasonably Possible, Amount of Unrecorded Benefit	$ 14

Income Taxes - Reconciliation t

Income Taxes - Reconciliation to Effective Tax Rate (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Effective Income Tax Rate Reconciliation, Percent [Abstract]
U.S. Federal statutory rate	21.00%	21.00%	21.00%	21.00%
Increase (decrease) due to:
State income taxes, net of Federal income tax benefit	1.40%	3.80%	(12.60%)	6.70%
Qualified nuclear decommissioning trust fund income	17.90%	18.80%	56.20%	(5.70%)
Effective Income Tax Rate Reconciliation, Deferred Prosecution Agreement payments		5.30%		4.80%
Amortization of investment tax credit, including deferred taxes on basis difference	0.00%	(0.60%)	(2.50%)	(1.00%)
Plant basis differences	(3.10%)	(1.60%)	(15.70%)	(3.70%)
Effective Income Tax Rate Reconciliation, Tax Credit, Other, Percent	(1.90%)	(1.40%)	(11.00%)	(2.20%)
Noncontrolling interests	(0.90%)	0.10%	(2.50%)	1.10%
Excess deferred tax amortization	(10.40%)	(15.50%)	(50.90%)	(20.90%)
Effective Income Tax Rate Reconciliation, Tax Settlement, Percent		(1.90%)		(9.30%)
Other	(10.60%)	(0.40%)	38.50%	0.70%
Effective income tax rate	13.40%	27.60%	20.50%	(8.50%)
Decrease in Unrecognized Tax Benefits is Reasonably Possible	$ 411		$ 411
Tax Adjustments, Settlements, and Unusual Provisions			76
Income Tax Expense (Benefit)	$ (74)	$ (219)	(55)	$ 75
Internal Revenue Service (IRS) [Member]
Increase (decrease) due to:
Income Tax Expense (Benefit)			$ 67
Exelon Generation Co L L C [Member]
Effective Income Tax Rate Reconciliation, Percent [Abstract]
U.S. Federal statutory rate	21.00%	21.00%	21.00%	21.00%
Increase (decrease) due to:
State income taxes, net of Federal income tax benefit	(1.30%)	3.10%	5.30%	7.20%
Qualified nuclear decommissioning trust fund income	85.20%	17.30%	(18.30%)	(16.00%)
Effective Income Tax Rate Reconciliation, Deferred Prosecution Agreement payments		0.00%		0.00%
Amortization of investment tax credit, including deferred taxes on basis difference	(1.80%)	(0.50%)	0.70%	(2.30%)
Plant basis differences	0.00%	0.00%	0.00%	0.00%
Effective Income Tax Rate Reconciliation, Tax Credit, Other, Percent	(13.00%)	(1.20%)	2.90%	(5.50%)
Noncontrolling interests	(4.20%)	0.10%	0.80%	3.20%
Excess deferred tax amortization	0.00%	0.00%	0.00%	0.00%
Effective Income Tax Rate Reconciliation, Tax Settlement, Percent		(1.80%)		(26.10%)
Other	2.80%	0.30%	(3.90%)	(0.30%)
Effective income tax rate	88.70%	38.30%	8.50%	(18.80%)
Decrease in Unrecognized Tax Benefits is Reasonably Possible	$ 411		$ 411
Tax Adjustments, Settlements, and Unusual Provisions			73
Income Tax Expense (Benefit)	$ (110)	$ (329)	70	$ 59
Exelon Generation Co L L C [Member] \| Internal Revenue Service (IRS) [Member]
Increase (decrease) due to:
Income Tax Expense (Benefit)			$ 67
Commonwealth Edison Co [Member]
Effective Income Tax Rate Reconciliation, Percent [Abstract]
U.S. Federal statutory rate	21.00%	21.00%	21.00%	21.00%
Increase (decrease) due to:
State income taxes, net of Federal income tax benefit	8.00%	(131.70%)	7.40%	19.10%
Qualified nuclear decommissioning trust fund income	0.00%	0.00%	0.00%	0.00%
Effective Income Tax Rate Reconciliation, Deferred Prosecution Agreement payments		(288.30%)		22.20%
Amortization of investment tax credit, including deferred taxes on basis difference	(0.10%)	2.90%	(0.10%)	(0.40%)
Plant basis differences	(0.70%)	2.40%	(0.60%)	(1.40%)
Effective Income Tax Rate Reconciliation, Tax Credit, Other, Percent	(0.80%)	3.30%	(0.50%)	(0.40%)
Noncontrolling interests	0.00%	0.00%	0.00%	0.00%
Excess deferred tax amortization	(7.00%)	116.00%	(7.00%)	(20.20%)
Effective Income Tax Rate Reconciliation, Tax Settlement, Percent		0.00%		0.00%
Other	(1.10%)	(32.30%)	(2.30%)	3.50%
Effective income tax rate	19.30%	(306.70%)	17.90%	43.40%
Income Tax Expense (Benefit)	$ (46)	$ (46)	$ (85)	$ (82)
PECO Energy Co [Member]
Effective Income Tax Rate Reconciliation, Percent [Abstract]
U.S. Federal statutory rate	21.00%	21.00%	21.00%	21.00%
Increase (decrease) due to:
State income taxes, net of Federal income tax benefit	(2.90%)	(9.70%)	(2.10%)	(1.60%)
Qualified nuclear decommissioning trust fund income	0.00%	0.00%	0.00%	0.00%
Effective Income Tax Rate Reconciliation, Deferred Prosecution Agreement payments		0.00%		0.00%
Amortization of investment tax credit, including deferred taxes on basis difference	0.00%	0.00%	0.00%	0.00%
Plant basis differences	(12.50%)	(23.60%)	(11.30%)	(11.00%)
Effective Income Tax Rate Reconciliation, Tax Credit, Other, Percent	0.00%	0.00%	0.00%	0.00%
Noncontrolling interests	0.00%	0.00%	0.00%	0.00%
Excess deferred tax amortization	(3.30%)	(4.80%)	(3.30%)	(3.30%)
Effective Income Tax Rate Reconciliation, Tax Settlement, Percent		0.00%		0.00%
Other	(0.40%)	(4.80%)	(0.10%)	(0.30%)
Effective income tax rate	1.90%	(21.90%)	4.20%	4.80%
Income Tax Expense (Benefit)	$ (2)	$ 7	$ (12)	$ (9)
Baltimore Gas and Electric Company [Member]
Effective Income Tax Rate Reconciliation, Percent [Abstract]
U.S. Federal statutory rate	21.00%	21.00%	21.00%	21.00%
Increase (decrease) due to:
State income taxes, net of Federal income tax benefit	(12.50%)	3.80%	(10.50%)	5.60%
Qualified nuclear decommissioning trust fund income	0.00%	0.00%	0.00%	0.00%
Effective Income Tax Rate Reconciliation, Deferred Prosecution Agreement payments		0.00%		0.00%
Amortization of investment tax credit, including deferred taxes on basis difference	(0.10%)	(0.20%)	(0.10%)	(0.10%)
Plant basis differences	(2.30%)	(13.40%)	(1.60%)	(2.00%)
Effective Income Tax Rate Reconciliation, Tax Credit, Other, Percent	(3.60%)	(1.00%)	(0.90%)	(0.20%)
Noncontrolling interests	0.00%	0.00%	0.00%	0.00%
Excess deferred tax amortization	(17.50%)	(137.90%)	(15.90%)	(16.10%)
Effective Income Tax Rate Reconciliation, Tax Settlement, Percent		0.00%		0.00%
Other	(6.60%)	(1.70%)	(1.00%)	(0.60%)
Effective income tax rate	(21.60%)	(129.40%)	(9.00%)	7.60%
Income Tax Expense (Benefit)	$ 8	$ 22	$ 21	$ (18)
Pepco Holdings LLC [Member]
Effective Income Tax Rate Reconciliation, Percent [Abstract]
U.S. Federal statutory rate	21.00%	21.00%	21.00%	21.00%
Increase (decrease) due to:
State income taxes, net of Federal income tax benefit	2.40%	(25.80%)	4.20%	4.30%
Qualified nuclear decommissioning trust fund income	0.00%	0.00%	0.00%	0.00%
Effective Income Tax Rate Reconciliation, Deferred Prosecution Agreement payments		0.00%		0.00%
Amortization of investment tax credit, including deferred taxes on basis difference	(0.10%)	(2.20%)	(0.10%)	(0.20%)
Plant basis differences	(1.10%)	(44.70%)	(1.30%)	(3.50%)
Effective Income Tax Rate Reconciliation, Tax Credit, Other, Percent	(0.80%)	(0.70%)	(0.50%)	(0.10%)
Noncontrolling interests	0.00%	0.00%	0.00%	0.00%
Excess deferred tax amortization	(22.30%)	(1358.50%)	(20.80%)	(80.30%)
Effective Income Tax Rate Reconciliation, Tax Settlement, Percent		0.00%		0.00%
Other	(1.30%)	168.00%	(0.70%)	(1.50%)
Effective income tax rate	(2.20%)	(1242.90%)	1.80%	(60.30%)
Income Tax Expense (Benefit)	$ 3	$ 87	$ (5)	$ 76
Potomac Electric Power Company [Member]
Effective Income Tax Rate Reconciliation, Percent [Abstract]
U.S. Federal statutory rate	21.00%	21.00%	21.00%	21.00%
Increase (decrease) due to:
State income taxes, net of Federal income tax benefit	(2.10%)	2.10%	1.50%	3.70%
Qualified nuclear decommissioning trust fund income	0.00%	0.00%	0.00%	0.00%
Effective Income Tax Rate Reconciliation, Deferred Prosecution Agreement payments		0.00%		0.00%
Amortization of investment tax credit, including deferred taxes on basis difference	0.00%	(0.10%)	0.00%	(0.10%)
Plant basis differences	(1.50%)	(3.90%)	(1.80%)	(2.70%)
Effective Income Tax Rate Reconciliation, Tax Credit, Other, Percent	(0.70%)	(0.10%)	(0.50%)	(0.10%)
Noncontrolling interests	0.00%	0.00%	0.00%	0.00%
Excess deferred tax amortization	(19.00%)	(89.00%)	(17.20%)	(41.60%)
Effective Income Tax Rate Reconciliation, Tax Settlement, Percent		0.00%		0.00%
Other	(1.90%)	(2.70%)	(0.80%)	(1.30%)
Effective income tax rate	(4.20%)	(72.70%)	2.20%	(21.10%)
Income Tax Expense (Benefit)	$ 3	$ 24	$ (3)	$ 19
Delmarva Power and Light Company [Member]
Effective Income Tax Rate Reconciliation, Percent [Abstract]
U.S. Federal statutory rate	21.00%	21.00%	21.00%	21.00%
Increase (decrease) due to:
State income taxes, net of Federal income tax benefit	7.00%	6.70%	6.60%	6.50%
Qualified nuclear decommissioning trust fund income	0.00%	0.00%	0.00%	0.00%
Effective Income Tax Rate Reconciliation, Deferred Prosecution Agreement payments		0.00%		0.00%
Amortization of investment tax credit, including deferred taxes on basis difference	(0.20%)	0.50%	(0.20%)	(0.30%)
Plant basis differences	(0.70%)	(1.10%)	(0.70%)	(0.60%)
Effective Income Tax Rate Reconciliation, Tax Credit, Other, Percent	(0.90%)	0.10%	(0.40%)	0.00%
Noncontrolling interests	0.00%	0.00%	0.00%	0.00%
Excess deferred tax amortization	(21.90%)	284.00%	(19.70%)	(72.90%)
Effective Income Tax Rate Reconciliation, Tax Settlement, Percent		0.00%		0.00%
Other	(1.10%)	(0.10%)	(0.10%)	0.80%
Effective income tax rate	3.20%	311.10%	6.50%	(45.50%)
Income Tax Expense (Benefit)	$ (1)	$ 28	$ (6)	$ 20
Atlantic City Electric Company [Member]
Effective Income Tax Rate Reconciliation, Percent [Abstract]
U.S. Federal statutory rate	21.00%	21.00%	21.00%	21.00%
Increase (decrease) due to:
State income taxes, net of Federal income tax benefit	8.10%	7.20%	7.80%	12.40%
Qualified nuclear decommissioning trust fund income	0.00%	0.00%	0.00%	0.00%
Effective Income Tax Rate Reconciliation, Deferred Prosecution Agreement payments		0.00%		0.00%
Amortization of investment tax credit, including deferred taxes on basis difference	(0.20%)	0.30%	(0.20%)	7.20%
Plant basis differences	(0.60%)	10.00%	(0.70%)	146.20%
Effective Income Tax Rate Reconciliation, Tax Credit, Other, Percent	(0.60%)	0.00%	(0.50%)	0.70%
Noncontrolling interests	0.00%	0.00%	0.00%	0.00%
Excess deferred tax amortization	(28.20%)	174.50%	(28.30%)	2613.80%
Effective Income Tax Rate Reconciliation, Tax Settlement, Percent		0.00%		0.00%
Other	(2.30%)	7.00%	(1.10%)	398.70%
Effective income tax rate	(2.80%)	220.00%	(2.00%)	3200.00%
Income Tax Expense (Benefit)	$ 1	$ 33	$ 1	$ 32

Income Taxes - Unrecognized Tax

Income Taxes - Unrecognized Tax Benefits (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Pepco Holdings LLC [Member]
Income Tax Contingency [Line Items]
Unrecognized Tax Benefits	$ 54	$ 52
Atlantic City Electric Company [Member]
Income Tax Contingency [Line Items]
Unrecognized Tax Benefits	$ 16	$ 15

Retirement Benefits - Narrative

Retirement Benefits - Narrative (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Mar. 31, 2021	Jun. 30, 2021
Defined Benefit Plan Disclosure [Line Items]
Increase (Decrease) in Obligation, Pension Benefits	$ 33
Increase (Decrease) in Obligation, Other Postretirement Benefits	(9)
Accumulated Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), after Tax	1
Defined Benefit Plan Amounts Recognized In Regulatory Assets Before Tax	21
Defined Benefit Plan Amounts Recognized In Regulatory Liabilities Before Tax	$ 1
Pension Plan, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Expected return on assets		7.00%
Discount rate		2.58%
Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Expected return on assets		6.46%
Discount rate		2.51%

Retirement Benefits - Calculati

Retirement Benefits - Calculation of Net Periodic Benefit Cost (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Amortization of:
Net periodic benefit cost	$ 26	$ 14	$ 46	$ 24
Pension Plan, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	111	96	220	193
Interest cost	160	190	320	379
Expected return on assets	(333)	(318)	(667)	(636)
Amortization of:
Prior service cost (credit)	0	1	1	2
Actuarial loss	149	128	299	256
Curtailment benefits			0	0
Settlement charges	4	6	4	6
Net periodic benefit cost	91	103	177	200
Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	20	22	40	45
Interest cost	28	39	57	77
Expected return on assets	(39)	(40)	(79)	(81)
Amortization of:
Prior service cost (credit)	(9)	(31)	(17)	(62)
Actuarial loss	10	12	19	24
Curtailment benefits			(1)	0
Settlement charges	0	0	0	0
Net periodic benefit cost	$ 10	$ 2	$ 19	$ 3

Retirement Benefits - Allocated

Retirement Benefits - Allocated Portion of Pension and Postretirement Benefit Plan Costs (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefits Costs			$ 196	$ 203
Pension and other post retirement benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefits Costs	$ 101	$ 105	196	203
Exelon Generation Co L L C [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefits Costs			56	58
Exelon Generation Co L L C [Member] \| Pension and other post retirement benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefits Costs	30	32	56	59
Commonwealth Edison Co [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefits Costs			64	57
Commonwealth Edison Co [Member] \| Pension and other post retirement benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefits Costs	32	28	64	57
PECO Energy Co [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefits Costs			4	3
PECO Energy Co [Member] \| Pension and other post retirement benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefits Costs	2	1	4	3
Baltimore Gas and Electric Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefits Costs			29	31
Baltimore Gas and Electric Company [Member] \| Pension and other post retirement benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefits Costs	16	16	31	31
Pepco Holdings LLC [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefits Costs			24	35
Pepco Holdings LLC [Member] \| Pension and other post retirement benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefits Costs	12	18	24	35
Potomac Electric Power Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefits Costs			3	7
Potomac Electric Power Company [Member] \| Pension and other post retirement benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefits Costs	2	4	3	7
Delmarva Power and Light Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefits Costs			1	4
Delmarva Power and Light Company [Member] \| Pension and other post retirement benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefits Costs	1	2	1	4
Atlantic City Electric Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefits Costs			5	7
Atlantic City Electric Company [Member] \| Pension and other post retirement benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefits Costs	$ 3	$ 3	$ 5	$ 7

Retirement Benefits - Defined C

Retirement Benefits - Defined Contribution Savings Plans (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Defined Benefit Plan Disclosure [Line Items]
Savings Plans Matching Contributions	$ 36	$ 34	$ 69	$ 67
Exelon Generation Co L L C [Member]
Defined Benefit Plan Disclosure [Line Items]
Savings Plans Matching Contributions	13	14	26	27
Commonwealth Edison Co [Member]
Defined Benefit Plan Disclosure [Line Items]
Savings Plans Matching Contributions	10	9	18	16
PECO Energy Co [Member]
Defined Benefit Plan Disclosure [Line Items]
Savings Plans Matching Contributions	3	2	6	5
Baltimore Gas and Electric Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Savings Plans Matching Contributions	2	2	4	4
Pepco Holdings LLC [Member]
Defined Benefit Plan Disclosure [Line Items]
Savings Plans Matching Contributions	4	3	7	6
Potomac Electric Power Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Savings Plans Matching Contributions	1	1	2	2
Delmarva Power and Light Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Savings Plans Matching Contributions	1	0	2	1
Atlantic City Electric Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Savings Plans Matching Contributions	$ 1	$ 1	$ 1	$ 1

Derivative Financial Instrume_3

Derivative Financial Instruments - Narrative (Details) MWh in Millions, $ in Millions	1 Months Ended	6 Months Ended
	Jun. 30, 2012MWh	Jun. 30, 2021USD ($)	Dec. 31, 2020USD ($)
Derivative [Line Items]
Incremental Collateral For Loss Of Investment Grade Credit Rating		$ 1,899	$ 1,432
Exelon Generation Co L L C [Member]
Derivative [Line Items]
Incremental Collateral For Loss Of Investment Grade Credit Rating		1,899	1,432
Commonwealth Edison Co [Member]
Derivative [Line Items]
Long-term Purchase Commitment, Minimum Energy Volume Required \| MWh	1.3
PECO Energy Co [Member]
Derivative [Line Items]
Incremental Collateral For Loss Of Investment Grade Credit Rating		22
Baltimore Gas and Electric Company [Member]
Derivative [Line Items]
Incremental Collateral For Loss Of Investment Grade Credit Rating		40
Delmarva Power and Light Company [Member]
Derivative [Line Items]
Incremental Collateral For Loss Of Investment Grade Credit Rating		$ 12
Minimum [Member] \| Exelon Generation Co L L C [Member]
Derivative [Line Items]
Expected Generation Hedged In Next Twelve Months		98.00%
Maximum [Member] \| Exelon Generation Co L L C [Member]
Derivative [Line Items]
Expected Generation Hedged In Next Twelve Months		101.00%
Not Designated as Hedging Instrument, Economic Hedge [Member]
Derivative [Line Items]
Derivative, Notional Amount		$ 629	665
Not Designated as Hedging Instrument, Economic Hedge [Member] \| Exelon Generation Co L L C [Member]
Derivative [Line Items]
Derivative, Notional Amount		$ 629	$ 665

Derivative Financial Instrume_4

Derivative Financial Instruments - Summary of Derivative Fair Value Balances (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Derivative [Line Items]
Mark-to-market derivative assets, current	$ 749	$ 644
Derivative Asset, Noncurrent	443	555
Mark-to-market derivative liabilities, current	(719)	(295)
Mark-to-market derivative liabilities, noncurrent	(554)	(473)
Margin Deposit Assets	(858)	(209)
Commodity Contract [Member]
Derivative [Line Items]
Mark-to-market derivative assets, current	748	639
Derivative Asset, Noncurrent	438	554
Total mark-to-market derivative assets	1,186	1,193
Mark-to-market derivative liabilities, current	(713)	(293)
Mark-to-market derivative liabilities, noncurrent	(553)	(472)
Total mark-to-market derivative liabilities	(1,266)	(765)
Total mark-to-market derivative net assets (liabilities)	(80)	428
Exelon Generation Co L L C [Member]
Derivative [Line Items]
Mark-to-market derivative assets, current	749	644
Derivative Asset, Noncurrent	441	555
Mark-to-market derivative liabilities, current	(695)	(262)
Mark-to-market derivative liabilities, noncurrent	(311)	(205)
Margin Deposit Assets	(858)	(209)
Exelon Generation Co L L C [Member] \| Commodity Contract [Member]
Derivative [Line Items]
Mark-to-market derivative assets, current	748	639
Derivative Asset, Noncurrent	438	554
Total mark-to-market derivative assets	1,186	1,193
Mark-to-market derivative liabilities, current	(690)	(260)
Mark-to-market derivative liabilities, noncurrent	(311)	(204)
Total mark-to-market derivative liabilities	(1,001)	(464)
Total mark-to-market derivative net assets (liabilities)	185	729
Commonwealth Edison Co [Member]
Derivative [Line Items]
Mark-to-market derivative liabilities, current		(33)
Mark-to-market derivative liabilities, noncurrent		(268)
Collateral [Member] \| Exelon Generation Co L L C [Member] \| Commodity Contract [Member]
Derivative [Line Items]
Mark-to-market derivative assets, current	(241)	103
Derivative Asset, Noncurrent	(92)	64
Total mark-to-market derivative assets	(333)	167
Mark-to-market derivative liabilities, current	(177)	131
Mark-to-market derivative liabilities, noncurrent	(42)	118
Total mark-to-market derivative liabilities	(219)	249
Total mark-to-market derivative net assets (liabilities)	(552)	416
Netting [Member] \| Exelon Generation Co L L C [Member] \| Commodity Contract [Member]
Derivative [Line Items]
Mark-to-market derivative assets, current	(5,616)	(2,261)
Derivative Asset, Noncurrent	(1,477)	(1,015)
Total mark-to-market derivative assets	(7,093)	(3,276)
Mark-to-market derivative liabilities, current	5,616	2,261
Mark-to-market derivative liabilities, noncurrent	1,477	1,015
Total mark-to-market derivative liabilities	7,093	3,276
Total mark-to-market derivative net assets (liabilities)	0	0
Not Designated as Hedging Instrument, Economic Hedge [Member] \| Exelon Generation Co L L C [Member] \| Commodity Contract [Member]
Derivative [Line Items]
Mark-to-market derivative assets, current	6,541	2,757
Derivative Asset, Noncurrent	1,997	1,501
Total mark-to-market derivative assets	8,538	4,258
Mark-to-market derivative liabilities, current	(6,075)	(2,629)
Mark-to-market derivative liabilities, noncurrent	(1,739)	(1,335)
Total mark-to-market derivative liabilities	(7,814)	(3,964)
Total mark-to-market derivative net assets (liabilities)	724	294
Not Designated as Hedging Instrument, Economic Hedge [Member] \| Commonwealth Edison Co [Member] \| Commodity Contract [Member]
Derivative [Line Items]
Mark-to-market derivative assets, current	0	0
Derivative Asset, Noncurrent	0	0
Total mark-to-market derivative assets	0	0
Mark-to-market derivative liabilities, current	(23)	(33)
Mark-to-market derivative liabilities, noncurrent	(242)	(268)
Total mark-to-market derivative liabilities	(265)	(301)
Total mark-to-market derivative net assets (liabilities)	(265)	(301)
Not Designated as Hedging Instrument, Trading [Member] \| Exelon Generation Co L L C [Member] \| Commodity Contract [Member]
Derivative [Line Items]
Mark-to-market derivative assets, current	64	40
Derivative Asset, Noncurrent	10	4
Total mark-to-market derivative assets	74	44
Mark-to-market derivative liabilities, current	(54)	(23)
Mark-to-market derivative liabilities, noncurrent	(7)	(2)
Total mark-to-market derivative liabilities	(61)	(25)
Total mark-to-market derivative net assets (liabilities)	$ 13	$ 19

Derivative Financial Instrume_5

Derivative Financial Instruments - Summary of Economic Hedges (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Derivative [Line Items]
Unrealized Gain (Loss) on Derivatives			$ 490	$ 194
Exelon Generation Co L L C [Member]
Derivative [Line Items]
Unrealized Gain (Loss) on Derivatives			490	193
Not Designated as Hedging Instrument, Economic Hedge [Member] \| Commodity Contract [Member]
Derivative [Line Items]
Unrealized Gain (Loss) on Derivatives	$ 312	$ 87	494	214
Not Designated as Hedging Instrument, Economic Hedge [Member] \| Commodity Contract [Member] \| Exelon Generation Co L L C [Member]
Derivative [Line Items]
Unrealized Gain (Loss) on Derivatives	312	87	494	214
Not Designated as Hedging Instrument, Economic Hedge [Member] \| Commodity Contract [Member] \| Operating revenues [Member]
Derivative [Line Items]
Unrealized Gain (Loss) on Derivatives	(240)	24	(323)	199
Not Designated as Hedging Instrument, Economic Hedge [Member] \| Commodity Contract [Member] \| Operating revenues [Member] \| Exelon Generation Co L L C [Member]
Derivative [Line Items]
Unrealized Gain (Loss) on Derivatives	(240)	24	(323)	199
Not Designated as Hedging Instrument, Economic Hedge [Member] \| Commodity Contract [Member] \| Purchased power and fuel [Member]
Derivative [Line Items]
Unrealized Gain (Loss) on Derivatives	552	63	817	15
Not Designated as Hedging Instrument, Economic Hedge [Member] \| Commodity Contract [Member] \| Purchased power and fuel [Member] \| Exelon Generation Co L L C [Member]
Derivative [Line Items]
Unrealized Gain (Loss) on Derivatives	$ 552	$ 63	$ 817	$ 15

Derivative Financial Instrume_6

Derivative Financial Instruments - Summary of Credit Risk Exposure (Details) - Exelon Generation Co L L C [Member] $ in Millions	6 Months Ended
	Jun. 30, 2021USD ($)
Derivative [Line Items]
Cash Collateral Held	$ 53
Letters Of Credit Held	40
Total Exposure Before Credit Collateral [Member]
Derivative [Line Items]
Concentration Risk, Credit Risk, Financial Instrument, Maximum Exposure	721
Total Exposure Before Credit Collateral [Member] \| Internal Investment Grade
Derivative [Line Items]
Concentration Risk, Credit Risk, Financial Instrument, Maximum Exposure	134
Total Exposure Before Credit Collateral [Member] \| Internal Noninvestment Grade
Derivative [Line Items]
Concentration Risk, Credit Risk, Financial Instrument, Maximum Exposure	126
Total Exposure Before Credit Collateral [Member] \| External Credit Rating, Investment Grade
Derivative [Line Items]
Concentration Risk, Credit Risk, Financial Instrument, Maximum Exposure	446
Total Exposure Before Credit Collateral [Member] \| External Credit Rating, Non Investment Grade
Derivative [Line Items]
Concentration Risk, Credit Risk, Financial Instrument, Maximum Exposure	15
Credit Collateral [Member]
Derivative [Line Items]
Concentration Risk, Credit Risk, Financial Instrument, Maximum Exposure	93
Credit Collateral [Member] \| Internal Investment Grade
Derivative [Line Items]
Concentration Risk, Credit Risk, Financial Instrument, Maximum Exposure	1
Credit Collateral [Member] \| Internal Noninvestment Grade
Derivative [Line Items]
Concentration Risk, Credit Risk, Financial Instrument, Maximum Exposure	35
Credit Collateral [Member] \| External Credit Rating, Investment Grade
Derivative [Line Items]
Concentration Risk, Credit Risk, Financial Instrument, Maximum Exposure	56
Credit Collateral [Member] \| External Credit Rating, Non Investment Grade
Derivative [Line Items]
Concentration Risk, Credit Risk, Financial Instrument, Maximum Exposure	1
Net Exposure [Member]
Derivative [Line Items]
Concentration Risk, Credit Risk, Financial Instrument, Maximum Exposure	628
Net Exposure [Member] \| Financial institutions [Domain]
Derivative [Line Items]
Concentration Risk, Credit Risk, Financial Instrument, Maximum Exposure	27
Net Exposure [Member] \| Investor-owned utilities, marketers, power producers
Derivative [Line Items]
Concentration Risk, Credit Risk, Financial Instrument, Maximum Exposure	448
Net Exposure [Member] \| Energy cooperatives and municipalities
Derivative [Line Items]
Concentration Risk, Credit Risk, Financial Instrument, Maximum Exposure	85
Net Exposure [Member] \| Other [Member]
Derivative [Line Items]
Concentration Risk, Credit Risk, Financial Instrument, Maximum Exposure	68
Net Exposure [Member] \| Internal Investment Grade
Derivative [Line Items]
Concentration Risk, Credit Risk, Financial Instrument, Maximum Exposure	133
Net Exposure [Member] \| Internal Noninvestment Grade
Derivative [Line Items]
Concentration Risk, Credit Risk, Financial Instrument, Maximum Exposure	91
Net Exposure [Member] \| External Credit Rating, Investment Grade
Derivative [Line Items]
Concentration Risk, Credit Risk, Financial Instrument, Maximum Exposure	390
Net Exposure [Member] \| External Credit Rating, Non Investment Grade
Derivative [Line Items]
Concentration Risk, Credit Risk, Financial Instrument, Maximum Exposure	$ 14
Number Of Counterparties Greater Than Ten Percent Of Net Exposure [Member]
Derivative [Line Items]
Number of Counterparties	0
Number Of Counterparties Greater Than Ten Percent Of Net Exposure [Member] \| External Credit Rating, Investment Grade
Derivative [Line Items]
Number of Counterparties	0
Net Exposure Of Counterparties Greater Than Ten Percent Of Net Exposure [Member]
Derivative [Line Items]
Concentration Risk, Credit Risk, Financial Instrument, Maximum Exposure	$ 0
Net Exposure Of Counterparties Greater Than Ten Percent Of Net Exposure [Member] \| External Credit Rating, Investment Grade
Derivative [Line Items]
Concentration Risk, Credit Risk, Financial Instrument, Maximum Exposure	$ 0

Derivative Financial Instrume_7

Derivative Financial Instruments - Summary of Credit Risk Related Contingent Features (Details) - Exelon Generation Co L L C [Member] - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Liability	$ (2,173)	$ (834)
Offsetting Fair Value of In-the-Money Contracts Under Master Netting Agreements	1,151	537
Derivative liabilities, fair value	$ (1,022)	$ (297)

Derivative Financial Instrume_8

Derivative Financial Instruments Derivative Financial Instruments - Summary of Cash Collateral and Letters of Credit (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Collateral, Right to Reclaim Cash	$ 67	$ 511
Derivative, Collateral, Right to Reclaim Securities	344	226
Derivative, Collateral, Obligation to Return Cash	621	110
Derivative, Collateral, Obligation to Return Securities	50	40
Incremental Collateral For Loss Of Investment Grade Credit Rating	1,899	1,432
Exelon Generation Co L L C [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Collateral, Right to Reclaim Cash	67	511
Derivative, Collateral, Right to Reclaim Securities	344	226
Derivative, Collateral, Obligation to Return Cash	621	110
Derivative, Collateral, Obligation to Return Securities	50	40
Incremental Collateral For Loss Of Investment Grade Credit Rating	$ 1,899	$ 1,432

Debt and Credit Agreements - Na

Debt and Credit Agreements - Narrative (Details) $ in Millions	6 Months Ended
	Jun. 30, 2021USD ($)
ShortTermDebt03232017 \| Corporate [Member]
Debt Instrument [Line Items]
Short-term Bank Loans and Notes Payable	$ 500
ShortTermDebt03242021 \| Corporate [Member]
Debt Instrument [Line Items]
Short-term Bank Loans and Notes Payable	200
ShortTermDebt03312021.1 \| Corporate [Member]
Debt Instrument [Line Items]
Short-term Bank Loans and Notes Payable	150
ShortTermDebt03312021.2 \| Corporate [Member]
Debt Instrument [Line Items]
Short-term Bank Loans and Notes Payable	150
ShortTermDebt03192020 \| Exelon Generation Co L L C [Member]
Debt Instrument [Line Items]
Short-term Bank Loans and Notes Payable	200
ShortTermDebt300 \| Exelon Generation Co L L C [Member]
Debt Instrument [Line Items]
Short-term Bank Loans and Notes Payable	300
ShortTermDebt01252021.1 \| Commonwealth Edison Co [Member]
Debt Instrument [Line Items]
Short-term Bank Loans and Notes Payable	125
ShortTermDebt01252021.2 \| Commonwealth Edison Co [Member]
Debt Instrument [Line Items]
Short-term Bank Loans and Notes Payable	125
ExGenBilatJan2013 \| Exelon Generation Co L L C [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	100
ExGenBilatFeb2019 \| Exelon Generation Co L L C [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	100
ExGenBilatJan2016 \| Exelon Generation Co L L C [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	150
WestMedMarch2026 \| Non-Recourse Debt [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	150
Non-Recourse Debt	150
WestMedMarch2026 \| Non-Recourse Debt [Member] \| Interest Rate Swap [Member]
Debt Instrument [Line Items]
Derivative, Notional Amount	$ 113
Derivative, Fixed Interest Rate	0.61%
WestMedMarch2026 \| Exelon Generation Co L L C [Member] \| Non-Recourse Debt [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate Terms	LIBOR + 3
Debt Instrument, Face Amount	$ 150
Non-Recourse Debt	150
WestMedMarch2026 \| Exelon Generation Co L L C [Member] \| Non-Recourse Debt [Member] \| Interest Rate Swap [Member]
Debt Instrument [Line Items]
Derivative, Notional Amount	$ 113
Derivative, Fixed Interest Rate	0.61%
London Interbank Offered Rate (LIBOR) [Member] \| ShortTermDebt03232017 \| Corporate [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate Terms	LIBOR plus 0.65
London Interbank Offered Rate (LIBOR) [Member] \| ShortTermDebt03242021 \| Corporate [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate Terms	LIBOR plus 0.65
London Interbank Offered Rate (LIBOR) [Member] \| ShortTermDebt03312021.1 \| Corporate [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate Terms	LIBOR plus 0.65
London Interbank Offered Rate (LIBOR) [Member] \| ShortTermDebt03312021.2 \| Corporate [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate Terms	LIBOR plus 0.65
London Interbank Offered Rate (LIBOR) [Member] \| ShortTermDebt03192020 \| Exelon Generation Co L L C [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate Terms	LIBOR plus 0.875
London Interbank Offered Rate (LIBOR) [Member] \| ShortTermDebt300 \| Exelon Generation Co L L C [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate Terms	LIBOR plus 0.70
London Interbank Offered Rate (LIBOR) [Member] \| ShortTermDebt01252021.1 \| Commonwealth Edison Co [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate Terms	LIBOR plus 0.50
London Interbank Offered Rate (LIBOR) [Member] \| ShortTermDebt01252021.2 \| Commonwealth Edison Co [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate Terms	LIBOR plus 0.75
London Interbank Offered Rate (LIBOR) [Member] \| WestMedMarch2026 \| Non-Recourse Debt [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate Terms	LIBOR plus 3
London Interbank Offered Rate (LIBOR) [Member] \| WestMedMarch2026 \| Exelon Generation Co L L C [Member] \| Non-Recourse Debt [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate Terms	LIBOR plus 3

Debt and Credit Agreements - Co

Debt and Credit Agreements - Commercial Paper Borrowings (Details) - Commercial Paper [Member] - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Short-term Debt [Line Items]
Commercial Paper	$ 365	$ 1,031
Short-term Debt, Weighted Average Interest Rate, at Point in Time	0.17%	0.25%
Corporate [Member]
Short-term Debt [Line Items]
Commercial Paper	$ 0	$ 0
Exelon Generation Co L L C [Member]
Short-term Debt [Line Items]
Commercial Paper	$ 0	$ 340
Short-term Debt, Weighted Average Interest Rate, at Point in Time	0.00%	0.27%
Commonwealth Edison Co [Member]
Short-term Debt [Line Items]
Commercial Paper	$ 33	$ 323
Short-term Debt, Weighted Average Interest Rate, at Point in Time	0.15%	0.23%
PECO Energy Co [Member]
Short-term Debt [Line Items]
Commercial Paper	$ 0	$ 0
Baltimore Gas and Electric Company [Member]
Short-term Debt [Line Items]
Commercial Paper	0	0
Pepco Holdings LLC [Member]
Short-term Debt [Line Items]
Commercial Paper	$ 332	$ 368
Short-term Debt, Weighted Average Interest Rate, at Point in Time	0.17%	0.24%
Potomac Electric Power Company [Member]
Short-term Debt [Line Items]
Commercial Paper	$ 154	$ 35
Short-term Debt, Weighted Average Interest Rate, at Point in Time	0.17%	0.22%
Delmarva Power and Light Company [Member]
Short-term Debt [Line Items]
Commercial Paper	$ 0	$ 146
Short-term Debt, Weighted Average Interest Rate, at Point in Time	0.00%	0.24%
Atlantic City Electric Company [Member]
Short-term Debt [Line Items]
Commercial Paper	$ 178	$ 187
Short-term Debt, Weighted Average Interest Rate, at Point in Time	0.18%	0.25%

Debt and Credit Agreements - Is

Debt and Credit Agreements - Issuance of Long-Term Debt (Details) $ in Millions	6 Months Ended
	Jun. 30, 2021USD ($)
WestMedMarch2026 \| Non-Recourse Debt [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 150
Corporate [Member] \| SoftAgree362Dec2025 \| Notes Payable to Banks [Member]
Debt Instrument [Line Items]
Interest Rate	3.62%
Debt Instrument, Face Amount	$ 4
Exelon Generation Co L L C [Member] \| WestMedMarch2026 \| Non-Recourse Debt [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate Terms	LIBOR + 3
Debt Instrument, Face Amount	$ 150
Exelon Generation Co L L C [Member] \| EEPF253April2021 \| Notes Payable, Other Payables[Member]
Debt Instrument [Line Items]
Interest Rate	2.53%
Debt Instrument, Face Amount	$ 1
Commonwealth Edison Co [Member] \| FMB313Mar2051 \| First Mortgage Bonds [Member]
Debt Instrument [Line Items]
Interest Rate	3.13%
Debt Instrument, Face Amount	$ 700
PECO Energy Co [Member] \| FMB305Mar2051 \| First Mortgage Bonds [Member]
Debt Instrument [Line Items]
Interest Rate	3.05%
Debt Instrument, Face Amount	$ 375
Baltimore Gas and Electric Company [Member] \| SN225June2031 \| Notes Payable, Other Payables[Member]
Debt Instrument [Line Items]
Interest Rate	2.25%
Debt Instrument, Face Amount	$ 600
Potomac Electric Power Company [Member] \| FMB232Mar2031 \| First Mortgage Bonds [Member]
Debt Instrument [Line Items]
Interest Rate	2.32%
Debt Instrument, Face Amount	$ 150
Potomac Electric Power Company [Member] \| FMB329Sep2051 \| First Mortgage Bonds [Member]
Debt Instrument [Line Items]
Interest Rate	3.29%
Debt Instrument, Face Amount	$ 125
Delmarva Power and Light Company [Member] \| FMB324Mar2051 \| First Mortgage Bonds [Member]
Debt Instrument [Line Items]
Interest Rate	3.24%
Debt Instrument, Face Amount	$ 125
Atlantic City Electric Company [Member] \| FMB230Mar2031 \| First Mortgage Bonds [Member]
Debt Instrument [Line Items]
Interest Rate	2.30%
Debt Instrument, Face Amount	$ 350

Fair Value of Financial Asset_3

Fair Value of Financial Assets and Liabilities - Narrative (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities without Readily Determinable Fair Value, Amount	$ 38	$ 73
Exelon Generation Co L L C [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities without Readily Determinable Fair Value, Amount	26	$ 55
Middle Market Lending [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Unfunded Commitments	364
Middle Market Lending [Member] \| Exelon Generation Co L L C [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Unfunded Commitments	364
Private Equity Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Unfunded Commitments	224
Private Equity Funds [Member] \| Exelon Generation Co L L C [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Unfunded Commitments	224
Real Estate Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Unfunded Commitments	320
Real Estate Funds [Member] \| Exelon Generation Co L L C [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Unfunded Commitments	$ 320

Fair Value of Financial Asset_4

Fair Value of Financial Assets and Liabilities - Fair Value of Financial Liabilities Recorded at Amortized Cost (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt to financing trust	$ 390	$ 390
Spent Nuclear Fuel Obligation, Noncurrent	1,209	1,208
Reported Value Measurement [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	38,710	36,912
Long-term debt to financing trust	390	390
Spent Nuclear Fuel Obligation, Noncurrent	1,209	1,208
Estimate of Fair Value Measurement [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	44,145	43,752
Long-term debt to financing trust	482	467
Spent Nuclear Fuel Obligation, Noncurrent	995	909
Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 1 [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	0	0
Long-term debt to financing trust	0	0
Spent Nuclear Fuel Obligation, Noncurrent	0	0
Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 2 [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	40,956	40,688
Long-term debt to financing trust	0	0
Spent Nuclear Fuel Obligation, Noncurrent	995	909
Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 3 [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	3,189	3,064
Long-term debt to financing trust	482	467
Spent Nuclear Fuel Obligation, Noncurrent	0	0
Exelon Generation Co L L C [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Spent Nuclear Fuel Obligation, Noncurrent	1,209	1,208
Exelon Generation Co L L C [Member] \| Reported Value Measurement [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	6,178	6,087
Spent Nuclear Fuel Obligation, Noncurrent	1,209	1,208
Exelon Generation Co L L C [Member] \| Estimate of Fair Value Measurement [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	6,921	6,856
Spent Nuclear Fuel Obligation, Noncurrent	995	909
Exelon Generation Co L L C [Member] \| Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 1 [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	0	0
Spent Nuclear Fuel Obligation, Noncurrent	0	0
Exelon Generation Co L L C [Member] \| Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 2 [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	5,776	5,648
Spent Nuclear Fuel Obligation, Noncurrent	995	909
Exelon Generation Co L L C [Member] \| Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 3 [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	1,145	1,208
Spent Nuclear Fuel Obligation, Noncurrent	0	0
Commonwealth Edison Co [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt to financing trust	205	205
Commonwealth Edison Co [Member] \| Reported Value Measurement [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	9,675	8,983
Long-term debt to financing trust	205	205
Commonwealth Edison Co [Member] \| Estimate of Fair Value Measurement [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	11,407	11,117
Long-term debt to financing trust	253	246
Commonwealth Edison Co [Member] \| Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 1 [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	0	0
Long-term debt to financing trust	0	0
Commonwealth Edison Co [Member] \| Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 2 [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	11,407	11,117
Long-term debt to financing trust	0	0
Commonwealth Edison Co [Member] \| Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 3 [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	0	0
Long-term debt to financing trust	253	246
PECO Energy Co [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt to financing trust	184	184
PECO Energy Co [Member] \| Reported Value Measurement [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	4,125	3,753
Long-term debt to financing trust	184	184
PECO Energy Co [Member] \| Estimate of Fair Value Measurement [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	4,772	4,603
Long-term debt to financing trust	229	221
PECO Energy Co [Member] \| Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 1 [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	0	0
Long-term debt to financing trust	0	0
PECO Energy Co [Member] \| Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 2 [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	4,722	4,553
Long-term debt to financing trust	0	0
PECO Energy Co [Member] \| Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 3 [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	50	50
Long-term debt to financing trust	229	221
Baltimore Gas and Electric Company [Member] \| Reported Value Measurement [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	4,259	3,664
Baltimore Gas and Electric Company [Member] \| Estimate of Fair Value Measurement [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	4,748	4,366
Baltimore Gas and Electric Company [Member] \| Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 1 [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	0	0
Baltimore Gas and Electric Company [Member] \| Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 2 [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	4,748	4,366
Baltimore Gas and Electric Company [Member] \| Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 3 [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	0	0
Pepco Holdings LLC [Member] \| Reported Value Measurement [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	7,369	7,006
Pepco Holdings LLC [Member] \| Estimate of Fair Value Measurement [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	8,042	7,905
Pepco Holdings LLC [Member] \| Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 1 [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	0	0
Pepco Holdings LLC [Member] \| Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 2 [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	6,048	6,099
Pepco Holdings LLC [Member] \| Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 3 [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	1,994	1,806
Potomac Electric Power Company [Member] \| Reported Value Measurement [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	3,318	3,165
Potomac Electric Power Company [Member] \| Estimate of Fair Value Measurement [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	4,100	4,084
Potomac Electric Power Company [Member] \| Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 1 [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	0	0
Potomac Electric Power Company [Member] \| Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 2 [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	3,240	3,336
Potomac Electric Power Company [Member] \| Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 3 [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	860	748
Delmarva Power and Light Company [Member] \| Reported Value Measurement [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	1,804	1,677
Delmarva Power and Light Company [Member] \| Estimate of Fair Value Measurement [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	1,990	1,939
Delmarva Power and Light Company [Member] \| Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 1 [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	0	0
Delmarva Power and Light Company [Member] \| Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 2 [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	1,434	1,484
Delmarva Power and Light Company [Member] \| Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 3 [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	556	455
Atlantic City Electric Company [Member] \| Reported Value Measurement [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	1,515	1,413
Atlantic City Electric Company [Member] \| Estimate of Fair Value Measurement [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	1,695	1,620
Atlantic City Electric Company [Member] \| Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 1 [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	0	0
Atlantic City Electric Company [Member] \| Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 2 [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	1,117	1,018
Atlantic City Electric Company [Member] \| Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 3 [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	$ 578	$ 602

Fair Value of Financial Asset_5

Fair Value of Financial Assets and Liabilities - Fair Value Measurements of Assets and Liabilities, Recurring and Nonrecurring (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2021	Dec. 31, 2020
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Mark-to-market derivative liabilities (current liabilities)	$ 719	$ 719	$ 295
Derivative Liability, Noncurrent	554	554	473
Margin Deposit Assets	(858)	(858)	(209)
Unrealized Gain (Loss) on Investments	119	96
Fair Value, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	1,167	1,167	686
DPP consideration	374	374	639
Assets, Fair Value Disclosure	19,047	19,047	17,776
Deferred Compensation Liability, Current and Noncurrent	(144)	(144)	(145)
Total Liabilities	(1,410)	(1,410)	(910)
Fair Value, Net Asset (Liability)	17,637	17,637	16,866
Derivative Instruments Not Designated as Hedging Instruments, Asset, at Fair Value	1	1	2
Derivative Asset, Notional Amount	2,016	2,016	1,043
Margin Deposit Assets	(858)	(858)	(209)
Derivative, Notional Amount	137	137	104
Fair Value, Recurring [Member] \| Investments in Equity
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Unrealized Gain (Loss) on Investments	102
Fair Value, Recurring [Member] \| Commodity Derivative Liabilites [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Total mark-to-market derivative liabilities	(1,266)	(1,266)	(765)
Fair Value, Recurring [Member] \| Economic Hedging Instrument Liabilites [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Total mark-to-market derivative liabilities	(8,079)	(8,079)	(4,265)
Fair Value, Recurring [Member] \| Proprietary Trading Liabilities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Total mark-to-market derivative liabilities	(61)	(61)	(25)
Fair Value, Recurring [Member] \| Effects of Netting and Allocation of Collateral Liabilites [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Total mark-to-market derivative liabilities	6,874	6,874	3,525
Fair Value, Recurring [Member] \| Cash and Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	728	728	409
Fair Value, Recurring [Member] \| Restricted cash member [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	114	114	59
Fair Value, Recurring [Member] \| Other Assets [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	52	52	53
Fair Value, Recurring [Member] \| Nuclear Decommissioning Trust Fund Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	15,690	15,690	14,780
Net assets (liabilities) excluded from nuclear decommissioning trust fund investments	94	94	181
Financial Instruments Sold, Not yet Purchased, Corporate Debt	(52)	(52)	(62)
Fair Value, Recurring [Member] \| Cash Equivalents NDT [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	627	627	305
Fair Value, Recurring [Member] \| Equity Securities Nuclear Decommissioning Trust Fund [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	8,161	8,161	7,525
Fair Value, Recurring [Member] \| Fixed Income Securities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	4,777	4,777	4,926
Fair Value, Recurring [Member] \| Corporate Debt Securities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	1,431	1,431	1,770
Fair Value, Recurring [Member] \| US Treasury and Government [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	2,091	2,091	1,997
Fair Value, Recurring [Member] \| Debt Security, Government, Non-US [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	51	51	56
Fair Value, Recurring [Member] \| State and municipal debt [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	28	28	101
Fair Value, Recurring [Member] \| Other Fixed Income [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	1,176	1,176	1,002
Fair Value, Recurring [Member] \| Middle Market Lending [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	783	783	841
Fair Value, Recurring [Member] \| Private Equity Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	580	580	504
Fair Value, Recurring [Member] \| Real Estate Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	762	762	679
Fair Value, Recurring [Member] \| Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	303	303	283
Fair Value, Recurring [Member] \| Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	65	65	60
Fair Value, Recurring [Member] \| Mutual Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	99	99	91
Fair Value, Recurring [Member] \| Fixed Income Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	11	11	11
Fair Value, Recurring [Member] \| 6311 Life Insurance [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	128	128	121
Fair Value, Recurring [Member] \| Equity Securities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	327	327	195
Fair Value, Recurring [Member] \| Commodity derivative assets [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	1,186	1,186	1,193
Fair Value, Recurring [Member] \| Economic Hedges [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	8,538	8,538	4,258
Fair Value, Recurring [Member] \| Proprietary Trading [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	74	74	44
Fair Value, Recurring [Member] \| Effects of netting and allocation of collateral [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	(7,426)	(7,426)	(3,109)
Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	1,167	1,167	686
DPP consideration	0	0	0
Assets, Fair Value Disclosure	9,434	9,434	7,137
Deferred Compensation Liability, Current and Noncurrent	0	0	0
Total Liabilities	(3)	(3)	(142)
Fair Value, Net Asset (Liability)	9,431	9,431	6,995
Collateral received from counterparties, net of collateral paid to counterparties	(169)	(169)	(67)
Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Commodity Derivative Liabilites [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Total mark-to-market derivative liabilities	(3)	(3)	(142)
Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Economic Hedging Instrument Liabilites [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Total mark-to-market derivative liabilities	(1,245)	(1,245)	(682)
Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Proprietary Trading Liabilities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Total mark-to-market derivative liabilities	0	0	0
Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Effects of Netting and Allocation of Collateral Liabilites [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Total mark-to-market derivative liabilities	1,242	1,242	540
Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Nuclear Decommissioning Trust Fund Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	7,406	7,406	5,967
Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Cash Equivalents NDT [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	552	552	210
Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Equity Securities Nuclear Decommissioning Trust Fund [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	4,770	4,770	3,886
Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Fixed Income Securities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	2,084	2,084	1,871
Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Corporate Debt Securities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| US Treasury and Government [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	2,052	2,052	1,871
Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Debt Security, Government, Non-US [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| State and municipal debt [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Other Fixed Income [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	32	32	0
Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Middle Market Lending [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Private Equity Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Real Estate Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	164	164	151
Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	65	65	60
Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Mutual Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	99	99	91
Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Fixed Income Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| 6311 Life Insurance [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Equity Securities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	327	327	195
Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Commodity derivative assets [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	370	370	138
Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Economic Hedges [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	1,781	1,781	745
Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Proprietary Trading [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	0	0	0
Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Effects of netting and allocation of collateral [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	(1,411)	(1,411)	(607)
Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	0	0	0
DPP consideration	374	374	639
Assets, Fair Value Disclosure	4,046	4,046	5,052
Deferred Compensation Liability, Current and Noncurrent	(144)	(144)	(145)
Total Liabilities	(338)	(338)	(176)
Fair Value, Net Asset (Liability)	3,708	3,708	4,876
Collateral received from counterparties, net of collateral paid to counterparties	(207)	(207)	321
Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Commodity Derivative Liabilites [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Total mark-to-market derivative liabilities	(194)	(194)	(31)
Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Economic Hedging Instrument Liabilites [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Total mark-to-market derivative liabilities	(3,444)	(3,444)	(1,928)
Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Proprietary Trading Liabilities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Total mark-to-market derivative liabilities	(45)	(45)	(21)
Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Effects of Netting and Allocation of Collateral Liabilites [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Total mark-to-market derivative liabilities	3,295	3,295	1,918
Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Nuclear Decommissioning Trust Fund Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	3,090	3,090	3,981
Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Cash Equivalents NDT [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	75	75	95
Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Equity Securities Nuclear Decommissioning Trust Fund [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	1,720	1,720	2,077
Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Fixed Income Securities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	1,295	1,295	1,809
Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Corporate Debt Securities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	1,146	1,146	1,485
Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| US Treasury and Government [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	39	39	126
Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Debt Security, Government, Non-US [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	51	51	56
Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| State and municipal debt [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	28	28	101
Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Other Fixed Income [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	31	31	41
Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Middle Market Lending [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Private Equity Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Real Estate Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	105	105	98
Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Mutual Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Fixed Income Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	11	11	11
Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| 6311 Life Insurance [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	94	94	87
Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Equity Securities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Commodity derivative assets [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	477	477	334
Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Economic Hedges [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	3,917	3,917	1,914
Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Proprietary Trading [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	62	62	17
Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Effects of netting and allocation of collateral [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	(3,502)	(3,502)	(1,597)
Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	0	0	0
DPP consideration	0	0	0
Assets, Fair Value Disclosure	834	834	1,252
Deferred Compensation Liability, Current and Noncurrent	0	0	0
Total Liabilities	(1,069)	(1,069)	(592)
Fair Value, Net Asset (Liability)	(235)	(235)	660
Collateral received from counterparties, net of collateral paid to counterparties	(176)	(176)	162
Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Commodity Derivative Liabilites [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Total mark-to-market derivative liabilities	(1,069)	(1,069)	(592)
Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Economic Hedging Instrument Liabilites [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Total mark-to-market derivative liabilities	(3,390)	(3,390)	(1,655)
Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Proprietary Trading Liabilities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Total mark-to-market derivative liabilities	(16)	(16)	(4)
Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Effects of Netting and Allocation of Collateral Liabilites [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Total mark-to-market derivative liabilities	2,337	2,337	1,067
Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Nuclear Decommissioning Trust Fund Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	461	461	497
Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Cash Equivalents NDT [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Equity Securities Nuclear Decommissioning Trust Fund [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Fixed Income Securities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	285	285	285
Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Corporate Debt Securities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	285	285	285
Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| US Treasury and Government [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Debt Security, Government, Non-US [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| State and municipal debt [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Other Fixed Income [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Middle Market Lending [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	176	176	212
Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Private Equity Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Real Estate Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	34	34	34
Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Mutual Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Fixed Income Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| 6311 Life Insurance [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	34	34	34
Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Equity Securities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Commodity derivative assets [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	339	339	721
Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Economic Hedges [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	2,840	2,840	1,599
Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Proprietary Trading [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	12	12	27
Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Effects of netting and allocation of collateral [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	(2,513)	(2,513)	(905)
Fair Value Measured at Net Asset Value Per Share [Member] \| Fair Value, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	0	0	0
DPP consideration	0	0	0
Assets, Fair Value Disclosure	4,733	4,733	4,335
Deferred Compensation Liability, Current and Noncurrent	0	0	0
Total Liabilities	0	0	0
Fair Value, Net Asset (Liability)	4,733	4,733	4,335
Fair Value Measured at Net Asset Value Per Share [Member] \| Fair Value, Recurring [Member] \| Commodity Derivative Liabilites [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Total mark-to-market derivative liabilities	0	0	0
Fair Value Measured at Net Asset Value Per Share [Member] \| Fair Value, Recurring [Member] \| Economic Hedging Instrument Liabilites [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Total mark-to-market derivative liabilities	0	0	0
Fair Value Measured at Net Asset Value Per Share [Member] \| Fair Value, Recurring [Member] \| Proprietary Trading Liabilities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Total mark-to-market derivative liabilities	0	0	0
Fair Value Measured at Net Asset Value Per Share [Member] \| Fair Value, Recurring [Member] \| Effects of Netting and Allocation of Collateral Liabilites [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Total mark-to-market derivative liabilities	0	0	0
Fair Value Measured at Net Asset Value Per Share [Member] \| Fair Value, Recurring [Member] \| Nuclear Decommissioning Trust Fund Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	4,733	4,733	4,335
Fair Value Measured at Net Asset Value Per Share [Member] \| Fair Value, Recurring [Member] \| Cash Equivalents NDT [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Fair Value Measured at Net Asset Value Per Share [Member] \| Fair Value, Recurring [Member] \| Equity Securities Nuclear Decommissioning Trust Fund [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	1,671	1,671	1,562
Fair Value Measured at Net Asset Value Per Share [Member] \| Fair Value, Recurring [Member] \| Fixed Income Securities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	1,113	1,113	961
Fair Value Measured at Net Asset Value Per Share [Member] \| Fair Value, Recurring [Member] \| Corporate Debt Securities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Fair Value Measured at Net Asset Value Per Share [Member] \| Fair Value, Recurring [Member] \| US Treasury and Government [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Fair Value Measured at Net Asset Value Per Share [Member] \| Fair Value, Recurring [Member] \| Debt Security, Government, Non-US [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Fair Value Measured at Net Asset Value Per Share [Member] \| Fair Value, Recurring [Member] \| State and municipal debt [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Fair Value Measured at Net Asset Value Per Share [Member] \| Fair Value, Recurring [Member] \| Other Fixed Income [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	1,113	1,113	961
Fair Value Measured at Net Asset Value Per Share [Member] \| Fair Value, Recurring [Member] \| Middle Market Lending [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	607	607	629
Fair Value Measured at Net Asset Value Per Share [Member] \| Fair Value, Recurring [Member] \| Private Equity Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	580	580	504
Fair Value Measured at Net Asset Value Per Share [Member] \| Fair Value, Recurring [Member] \| Real Estate Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	762	762	679
Fair Value Measured at Net Asset Value Per Share [Member] \| Fair Value, Recurring [Member] \| Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Fair Value Measured at Net Asset Value Per Share [Member] \| Fair Value, Recurring [Member] \| Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Fair Value Measured at Net Asset Value Per Share [Member] \| Fair Value, Recurring [Member] \| Mutual Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Fair Value Measured at Net Asset Value Per Share [Member] \| Fair Value, Recurring [Member] \| Fixed Income Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Fair Value Measured at Net Asset Value Per Share [Member] \| Fair Value, Recurring [Member] \| 6311 Life Insurance [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Fair Value Measured at Net Asset Value Per Share [Member] \| Fair Value, Recurring [Member] \| Equity Securities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Fair Value Measured at Net Asset Value Per Share [Member] \| Fair Value, Recurring [Member] \| Commodity derivative assets [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	0	0	0
Fair Value Measured at Net Asset Value Per Share [Member] \| Fair Value, Recurring [Member] \| Economic Hedges [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	0	0	0
Fair Value Measured at Net Asset Value Per Share [Member] \| Fair Value, Recurring [Member] \| Proprietary Trading [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	0	0	0
Fair Value Measured at Net Asset Value Per Share [Member] \| Fair Value, Recurring [Member] \| Effects of netting and allocation of collateral [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	0	0	0
Exelon Generation Co L L C [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	1,022	1,022	297
Mark-to-market derivative liabilities (current liabilities)	695	695	262
Derivative Liability, Noncurrent	311	311	205
Margin Deposit Assets	(858)	(858)	(209)
Unrealized Gain (Loss) on Investments	119	96
Exelon Generation Co L L C [Member] \| Fair Value, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	162	162	124
DPP consideration	374	374	639
Assets, Fair Value Disclosure	17,807	17,807	16,992
Deferred Compensation Liability, Current and Noncurrent	(42)	(42)	(42)
Total Liabilities	(1,043)	(1,043)	(506)
Fair Value, Net Asset (Liability)	16,764	16,764	16,486
Derivative Instruments Not Designated as Hedging Instruments, Asset, at Fair Value	1	1	2
Derivative Asset, Notional Amount	2,016	2,016	1,043
Margin Deposit Assets	(858)	(858)	(209)
Derivative, Notional Amount	137	137	104
Exelon Generation Co L L C [Member] \| Fair Value, Recurring [Member] \| Investments in Equity
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Unrealized Gain (Loss) on Investments	102	220
Exelon Generation Co L L C [Member] \| Fair Value, Recurring [Member] \| Commodity Derivative Liabilites [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Total mark-to-market derivative liabilities	(1,001)	(1,001)	(464)
Exelon Generation Co L L C [Member] \| Fair Value, Recurring [Member] \| Economic Hedging Instrument Liabilites [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Total mark-to-market derivative liabilities	(7,814)	(7,814)	(3,964)
Exelon Generation Co L L C [Member] \| Fair Value, Recurring [Member] \| Proprietary Trading Liabilities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Total mark-to-market derivative liabilities	(61)	(61)	(25)
Exelon Generation Co L L C [Member] \| Fair Value, Recurring [Member] \| Effects of Netting and Allocation of Collateral Liabilites [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Total mark-to-market derivative liabilities	6,874	6,874	3,525
Exelon Generation Co L L C [Member] \| Fair Value, Recurring [Member] \| Cash and Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	407	407	171
Exelon Generation Co L L C [Member] \| Fair Value, Recurring [Member] \| Restricted cash member [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	32	32	20
Exelon Generation Co L L C [Member] \| Fair Value, Recurring [Member] \| Nuclear Decommissioning Trust Fund Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	15,690	15,690	14,780
Net assets (liabilities) excluded from nuclear decommissioning trust fund investments	94	94	181
Exelon Generation Co L L C [Member] \| Fair Value, Recurring [Member] \| Cash Equivalents NDT [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	627	627	305
Exelon Generation Co L L C [Member] \| Fair Value, Recurring [Member] \| Equity Securities Nuclear Decommissioning Trust Fund [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	8,161	8,161	7,525
Exelon Generation Co L L C [Member] \| Fair Value, Recurring [Member] \| Fixed Income Securities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	4,777	4,777	4,926
Exelon Generation Co L L C [Member] \| Fair Value, Recurring [Member] \| Corporate Debt Securities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	1,431	1,431	1,770
Exelon Generation Co L L C [Member] \| Fair Value, Recurring [Member] \| US Treasury and Government [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	2,091	2,091	1,997
Exelon Generation Co L L C [Member] \| Fair Value, Recurring [Member] \| Debt Security, Government, Non-US [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	51	51	56
Exelon Generation Co L L C [Member] \| Fair Value, Recurring [Member] \| State and municipal debt [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	28	28	101
Exelon Generation Co L L C [Member] \| Fair Value, Recurring [Member] \| Other Fixed Income [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	1,176	1,176	1,002
Exelon Generation Co L L C [Member] \| Fair Value, Recurring [Member] \| Middle Market Lending [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	783	783	841
Exelon Generation Co L L C [Member] \| Fair Value, Recurring [Member] \| Private Equity Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	580	580	504
Exelon Generation Co L L C [Member] \| Fair Value, Recurring [Member] \| Real Estate Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	762	762	679
Exelon Generation Co L L C [Member] \| Fair Value, Recurring [Member] \| Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	68	68	61
Exelon Generation Co L L C [Member] \| Fair Value, Recurring [Member] \| Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	4	4	4
Exelon Generation Co L L C [Member] \| Fair Value, Recurring [Member] \| Mutual Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	33	33	29
Exelon Generation Co L L C [Member] \| Fair Value, Recurring [Member] \| Fixed Income Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Exelon Generation Co L L C [Member] \| Fair Value, Recurring [Member] \| 6311 Life Insurance [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	31	31	28
Exelon Generation Co L L C [Member] \| Fair Value, Recurring [Member] \| Equity Securities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	327	327	195
Exelon Generation Co L L C [Member] \| Fair Value, Recurring [Member] \| Commodity derivative assets [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	1,186	1,186	1,193
Exelon Generation Co L L C [Member] \| Fair Value, Recurring [Member] \| Economic Hedges [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	8,538	8,538	4,258
Exelon Generation Co L L C [Member] \| Fair Value, Recurring [Member] \| Proprietary Trading [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	74	74	44
Exelon Generation Co L L C [Member] \| Fair Value, Recurring [Member] \| Effects of netting and allocation of collateral [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	(7,426)	(7,426)	(3,109)
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	162	162	124
DPP consideration	0	0	0
Assets, Fair Value Disclosure	8,302	8,302	6,457
Deferred Compensation Liability, Current and Noncurrent	0	0	0
Total Liabilities	(3)	(3)	(142)
Fair Value, Net Asset (Liability)	8,299	8,299	6,315
Collateral received from counterparties, net of collateral paid to counterparties	(169)	(169)	(67)
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Commodity Derivative Liabilites [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Total mark-to-market derivative liabilities	(3)	(3)	(142)
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Economic Hedging Instrument Liabilites [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Total mark-to-market derivative liabilities	(1,245)	(1,245)	(682)
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Proprietary Trading Liabilities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Total mark-to-market derivative liabilities	0	0	0
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Effects of Netting and Allocation of Collateral Liabilites [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Total mark-to-market derivative liabilities	1,242	1,242	540
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Nuclear Decommissioning Trust Fund Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	7,406	7,406	5,967
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Cash Equivalents NDT [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	552	552	210
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Equity Securities Nuclear Decommissioning Trust Fund [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	4,770	4,770	3,886
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Fixed Income Securities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	2,084	2,084	1,871
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Corporate Debt Securities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| US Treasury and Government [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	2,052	2,052	1,871
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Debt Security, Government, Non-US [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| State and municipal debt [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Other Fixed Income [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	32	32	0
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Middle Market Lending [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Private Equity Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Real Estate Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	37	37	33
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	4	4	4
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Mutual Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	33	33	29
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Fixed Income Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| 6311 Life Insurance [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Equity Securities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	327	327	195
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Commodity derivative assets [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	370	370	138
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Economic Hedges [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	1,781	1,781	745
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Proprietary Trading [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	0	0	0
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Effects of netting and allocation of collateral [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	(1,411)	(1,411)	(607)
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	0	0	0
DPP consideration	374	374	639
Assets, Fair Value Disclosure	3,972	3,972	4,982
Deferred Compensation Liability, Current and Noncurrent	(42)	(42)	(42)
Total Liabilities	(236)	(236)	(73)
Fair Value, Net Asset (Liability)	3,736	3,736	4,909
Collateral received from counterparties, net of collateral paid to counterparties	(207)	(207)	321
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Commodity Derivative Liabilites [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Total mark-to-market derivative liabilities	(194)	(194)	(31)
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Economic Hedging Instrument Liabilites [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Total mark-to-market derivative liabilities	(3,444)	(3,444)	(1,928)
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Proprietary Trading Liabilities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Total mark-to-market derivative liabilities	(45)	(45)	(21)
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Effects of Netting and Allocation of Collateral Liabilites [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Total mark-to-market derivative liabilities	3,295	3,295	1,918
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Nuclear Decommissioning Trust Fund Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	3,090	3,090	3,981
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Cash Equivalents NDT [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	75	75	95
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Equity Securities Nuclear Decommissioning Trust Fund [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	1,720	1,720	2,077
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Fixed Income Securities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	1,295	1,295	1,809
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Corporate Debt Securities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	1,146	1,146	1,485
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| US Treasury and Government [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	39	39	126
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Debt Security, Government, Non-US [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	51	51	56
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| State and municipal debt [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	28	28	101
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Other Fixed Income [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	31	31	41
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Middle Market Lending [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Private Equity Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Real Estate Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	31	31	28
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Mutual Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Fixed Income Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| 6311 Life Insurance [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	31	31	28
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Equity Securities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Commodity derivative assets [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	477	477	334
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Economic Hedges [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	3,917	3,917	1,914
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Proprietary Trading [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	62	62	17
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Effects of netting and allocation of collateral [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	(3,502)	(3,502)	(1,597)
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	0	0	0
DPP consideration	0	0	0
Assets, Fair Value Disclosure	800	800	1,218
Deferred Compensation Liability, Current and Noncurrent	0	0	0
Total Liabilities	(804)	(804)	(291)
Fair Value, Net Asset (Liability)	(4)	(4)	927
Collateral received from counterparties, net of collateral paid to counterparties	(176)	(176)	162
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Commodity Derivative Liabilites [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Total mark-to-market derivative liabilities	(804)	(804)	(291)
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Economic Hedging Instrument Liabilites [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Total mark-to-market derivative liabilities	(3,125)	(3,125)	(1,354)
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Proprietary Trading Liabilities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Total mark-to-market derivative liabilities	(16)	(16)	(4)
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Effects of Netting and Allocation of Collateral Liabilites [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Total mark-to-market derivative liabilities	2,337	2,337	1,067
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Nuclear Decommissioning Trust Fund Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	461	461	497
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Cash Equivalents NDT [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Equity Securities Nuclear Decommissioning Trust Fund [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Fixed Income Securities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	285	285	285
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Corporate Debt Securities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	285	285	285
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| US Treasury and Government [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Debt Security, Government, Non-US [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| State and municipal debt [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Other Fixed Income [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Middle Market Lending [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	176	176	212
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Private Equity Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Real Estate Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Mutual Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Fixed Income Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| 6311 Life Insurance [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Equity Securities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Commodity derivative assets [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	339	339	721
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Economic Hedges [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	2,840	2,840	1,599
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Proprietary Trading [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	12	12	27
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Effects of netting and allocation of collateral [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	(2,513)	(2,513)	(905)
Exelon Generation Co L L C [Member] \| Fair Value Measured at Net Asset Value Per Share [Member] \| Fair Value, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	0	0	0
DPP consideration	0	0	0
Assets, Fair Value Disclosure	4,733	4,733	4,335
Deferred Compensation Liability, Current and Noncurrent	0	0	0
Total Liabilities	0	0	0
Fair Value, Net Asset (Liability)	4,733	4,733	4,335
Exelon Generation Co L L C [Member] \| Fair Value Measured at Net Asset Value Per Share [Member] \| Fair Value, Recurring [Member] \| Commodity Derivative Liabilites [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Total mark-to-market derivative liabilities	0	0	0
Exelon Generation Co L L C [Member] \| Fair Value Measured at Net Asset Value Per Share [Member] \| Fair Value, Recurring [Member] \| Economic Hedging Instrument Liabilites [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Total mark-to-market derivative liabilities	0	0	0
Exelon Generation Co L L C [Member] \| Fair Value Measured at Net Asset Value Per Share [Member] \| Fair Value, Recurring [Member] \| Proprietary Trading Liabilities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Total mark-to-market derivative liabilities	0	0	0
Exelon Generation Co L L C [Member] \| Fair Value Measured at Net Asset Value Per Share [Member] \| Fair Value, Recurring [Member] \| Effects of Netting and Allocation of Collateral Liabilites [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Total mark-to-market derivative liabilities	0	0	0
Exelon Generation Co L L C [Member] \| Fair Value Measured at Net Asset Value Per Share [Member] \| Fair Value, Recurring [Member] \| Nuclear Decommissioning Trust Fund Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	4,733	4,733	4,335
Exelon Generation Co L L C [Member] \| Fair Value Measured at Net Asset Value Per Share [Member] \| Fair Value, Recurring [Member] \| Cash Equivalents NDT [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Exelon Generation Co L L C [Member] \| Fair Value Measured at Net Asset Value Per Share [Member] \| Fair Value, Recurring [Member] \| Equity Securities Nuclear Decommissioning Trust Fund [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	1,671	1,671	1,562
Exelon Generation Co L L C [Member] \| Fair Value Measured at Net Asset Value Per Share [Member] \| Fair Value, Recurring [Member] \| Fixed Income Securities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	1,113	1,113	961
Exelon Generation Co L L C [Member] \| Fair Value Measured at Net Asset Value Per Share [Member] \| Fair Value, Recurring [Member] \| Corporate Debt Securities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Exelon Generation Co L L C [Member] \| Fair Value Measured at Net Asset Value Per Share [Member] \| Fair Value, Recurring [Member] \| US Treasury and Government [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Exelon Generation Co L L C [Member] \| Fair Value Measured at Net Asset Value Per Share [Member] \| Fair Value, Recurring [Member] \| Debt Security, Government, Non-US [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Exelon Generation Co L L C [Member] \| Fair Value Measured at Net Asset Value Per Share [Member] \| Fair Value, Recurring [Member] \| State and municipal debt [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Exelon Generation Co L L C [Member] \| Fair Value Measured at Net Asset Value Per Share [Member] \| Fair Value, Recurring [Member] \| Other Fixed Income [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	1,113	1,113	961
Exelon Generation Co L L C [Member] \| Fair Value Measured at Net Asset Value Per Share [Member] \| Fair Value, Recurring [Member] \| Middle Market Lending [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	607	607	629
Exelon Generation Co L L C [Member] \| Fair Value Measured at Net Asset Value Per Share [Member] \| Fair Value, Recurring [Member] \| Private Equity Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	580	580	504
Exelon Generation Co L L C [Member] \| Fair Value Measured at Net Asset Value Per Share [Member] \| Fair Value, Recurring [Member] \| Real Estate Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	762	762	679
Exelon Generation Co L L C [Member] \| Fair Value Measured at Net Asset Value Per Share [Member] \| Fair Value, Recurring [Member] \| Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Exelon Generation Co L L C [Member] \| Fair Value Measured at Net Asset Value Per Share [Member] \| Fair Value, Recurring [Member] \| Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Exelon Generation Co L L C [Member] \| Fair Value Measured at Net Asset Value Per Share [Member] \| Fair Value, Recurring [Member] \| Mutual Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Exelon Generation Co L L C [Member] \| Fair Value Measured at Net Asset Value Per Share [Member] \| Fair Value, Recurring [Member] \| Fixed Income Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Exelon Generation Co L L C [Member] \| Fair Value Measured at Net Asset Value Per Share [Member] \| Fair Value, Recurring [Member] \| 6311 Life Insurance [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Exelon Generation Co L L C [Member] \| Fair Value Measured at Net Asset Value Per Share [Member] \| Fair Value, Recurring [Member] \| Equity Securities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Exelon Generation Co L L C [Member] \| Fair Value Measured at Net Asset Value Per Share [Member] \| Fair Value, Recurring [Member] \| Commodity derivative assets [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	0	0	0
Exelon Generation Co L L C [Member] \| Fair Value Measured at Net Asset Value Per Share [Member] \| Fair Value, Recurring [Member] \| Economic Hedges [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	0	0	0
Exelon Generation Co L L C [Member] \| Fair Value Measured at Net Asset Value Per Share [Member] \| Fair Value, Recurring [Member] \| Proprietary Trading [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	0	0	0
Exelon Generation Co L L C [Member] \| Fair Value Measured at Net Asset Value Per Share [Member] \| Fair Value, Recurring [Member] \| Effects of netting and allocation of collateral [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	0	0	0
Commonwealth Edison Co [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Mark-to-market derivative liabilities (current liabilities)			33
Derivative Liability, Noncurrent			268
Unrealized Gain (Loss) on Investments	0	0
Commonwealth Edison Co [Member] \| Fair Value, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	264	264	285
Assets, Fair Value Disclosure	264	264	285
Total mark-to-market derivative liabilities	(265)	(265)	(301)
Deferred Compensation Liability, Current and Noncurrent	(9)	(9)	(8)
Total Liabilities	(274)	(274)	(309)
Fair Value, Net Asset (Liability)	(10)	(10)	(24)
Mark-to-market derivative liabilities (current liabilities)	23	23	33
Derivative Liability, Noncurrent	242	242	268
Commonwealth Edison Co [Member] \| Fair Value, Recurring [Member] \| Cash and Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	44	44	83
Commonwealth Edison Co [Member] \| Fair Value, Recurring [Member] \| Restricted cash member [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	46	46	37
Commonwealth Edison Co [Member] \| Fair Value, Recurring [Member] \| Other Assets [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	43	43	43
Commonwealth Edison Co [Member] \| Fair Value, Recurring [Member] \| Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Commonwealth Edison Co [Member] \| Fair Value, Recurring [Member] \| Mutual Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Commonwealth Edison Co [Member] \| Fair Value, Recurring [Member] \| 6311 Life Insurance [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Commonwealth Edison Co [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	264	264	285
Assets, Fair Value Disclosure	264	264	285
Total mark-to-market derivative liabilities	0	0	0
Deferred Compensation Liability, Current and Noncurrent	0	0	0
Total Liabilities	0	0	0
Fair Value, Net Asset (Liability)	264	264	285
Commonwealth Edison Co [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Commonwealth Edison Co [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Mutual Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Commonwealth Edison Co [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| 6311 Life Insurance [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Commonwealth Edison Co [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	0	0	0
Assets, Fair Value Disclosure	0	0	0
Total mark-to-market derivative liabilities	0	0	0
Deferred Compensation Liability, Current and Noncurrent	(9)	(9)	(8)
Total Liabilities	(9)	(9)	(8)
Fair Value, Net Asset (Liability)	(9)	(9)	(8)
Commonwealth Edison Co [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Commonwealth Edison Co [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Mutual Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Commonwealth Edison Co [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| 6311 Life Insurance [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Commonwealth Edison Co [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	0	0	0
Assets, Fair Value Disclosure	0	0	0
Total mark-to-market derivative liabilities	(265)	(265)	(301)
Deferred Compensation Liability, Current and Noncurrent	0	0	0
Total Liabilities	(265)	(265)	(301)
Fair Value, Net Asset (Liability)	(265)	(265)	(301)
Commonwealth Edison Co [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Commonwealth Edison Co [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Mutual Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Commonwealth Edison Co [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| 6311 Life Insurance [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
PECO Energy Co [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Unrealized Gain (Loss) on Investments	0	0
PECO Energy Co [Member] \| Fair Value, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	230	230	8
Assets, Fair Value Disclosure	255	255	30
Total mark-to-market derivative liabilities	0	0	0
Deferred Compensation Liability, Current and Noncurrent	(8)	(8)	(9)
Total Liabilities	(8)	(8)	(9)
Fair Value, Net Asset (Liability)	247	247	21
PECO Energy Co [Member] \| Fair Value, Recurring [Member] \| Cash and Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	154	154	18
PECO Energy Co [Member] \| Fair Value, Recurring [Member] \| Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	25	25	22
PECO Energy Co [Member] \| Fair Value, Recurring [Member] \| Mutual Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	10	10	9
PECO Energy Co [Member] \| Fair Value, Recurring [Member] \| 6311 Life Insurance [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	15	15	13
PECO Energy Co [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	230	230	8
Assets, Fair Value Disclosure	240	240	17
Total mark-to-market derivative liabilities	0	0	0
Deferred Compensation Liability, Current and Noncurrent	0	0	0
Total Liabilities	0	0	0
Fair Value, Net Asset (Liability)	240	240	17
PECO Energy Co [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	10	10	9
PECO Energy Co [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Mutual Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	10	10	9
PECO Energy Co [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| 6311 Life Insurance [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
PECO Energy Co [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	0	0	0
Assets, Fair Value Disclosure	15	15	13
Total mark-to-market derivative liabilities	0	0	0
Deferred Compensation Liability, Current and Noncurrent	(8)	(8)	(9)
Total Liabilities	(8)	(8)	(9)
Fair Value, Net Asset (Liability)	7	7	4
PECO Energy Co [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	15	15	13
PECO Energy Co [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Mutual Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
PECO Energy Co [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| 6311 Life Insurance [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	15	15	13
PECO Energy Co [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	0	0	0
Assets, Fair Value Disclosure	0	0	0
Total mark-to-market derivative liabilities	0	0	0
Deferred Compensation Liability, Current and Noncurrent	0	0	0
Total Liabilities	0	0	0
Fair Value, Net Asset (Liability)	0	0	0
PECO Energy Co [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
PECO Energy Co [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Mutual Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
PECO Energy Co [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| 6311 Life Insurance [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Baltimore Gas and Electric Company [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Unrealized Gain (Loss) on Investments	0	0
Baltimore Gas and Electric Company [Member] \| Fair Value, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	334	334	120
Assets, Fair Value Disclosure	348	348	130
Total mark-to-market derivative liabilities	0	0	0
Deferred Compensation Liability, Current and Noncurrent	(6)	(6)	(5)
Total Liabilities	(6)	(6)	(5)
Fair Value, Net Asset (Liability)	342	342	125
Baltimore Gas and Electric Company [Member] \| Fair Value, Recurring [Member] \| Cash and Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	34	34	24
Baltimore Gas and Electric Company [Member] \| Fair Value, Recurring [Member] \| Restricted cash member [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	3	3	1
Baltimore Gas and Electric Company [Member] \| Fair Value, Recurring [Member] \| Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	14	14	10
Baltimore Gas and Electric Company [Member] \| Fair Value, Recurring [Member] \| Mutual Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	14	14	10
Baltimore Gas and Electric Company [Member] \| Fair Value, Recurring [Member] \| 6311 Life Insurance [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Baltimore Gas and Electric Company [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	334	334	120
Assets, Fair Value Disclosure	348	348	130
Total mark-to-market derivative liabilities	0	0	0
Deferred Compensation Liability, Current and Noncurrent	0	0	0
Total Liabilities	0	0	0
Fair Value, Net Asset (Liability)	348	348	130
Baltimore Gas and Electric Company [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	14	14	10
Baltimore Gas and Electric Company [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Mutual Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	14	14	10
Baltimore Gas and Electric Company [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| 6311 Life Insurance [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Baltimore Gas and Electric Company [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	0	0	0
Assets, Fair Value Disclosure	0	0	0
Total mark-to-market derivative liabilities	0	0	0
Deferred Compensation Liability, Current and Noncurrent	(6)	(6)	(5)
Total Liabilities	(6)	(6)	(5)
Fair Value, Net Asset (Liability)	(6)	(6)	(5)
Baltimore Gas and Electric Company [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Baltimore Gas and Electric Company [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Mutual Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Baltimore Gas and Electric Company [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| 6311 Life Insurance [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Baltimore Gas and Electric Company [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	0	0	0
Assets, Fair Value Disclosure	0	0	0
Total mark-to-market derivative liabilities	0	0	0
Deferred Compensation Liability, Current and Noncurrent	0	0	0
Total Liabilities	0	0	0
Fair Value, Net Asset (Liability)	0	0	0
Baltimore Gas and Electric Company [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Baltimore Gas and Electric Company [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Mutual Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Baltimore Gas and Electric Company [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| 6311 Life Insurance [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Pepco Holdings LLC [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Unrealized Gain (Loss) on Investments	0	0
Pepco Holdings LLC [Member] \| Fair Value, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	46	46	86
Assets, Fair Value Disclosure	190	190	226
Deferred Compensation Liability, Current and Noncurrent	(16)	(16)	(17)
Total Liabilities	(16)	(16)	(17)
Fair Value, Net Asset (Liability)	174	174	209
Pepco Holdings LLC [Member] \| Fair Value, Recurring [Member] \| Cash and Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	61	61	74
Pepco Holdings LLC [Member] \| Fair Value, Recurring [Member] \| Restricted cash member [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	5	5	0
Pepco Holdings LLC [Member] \| Fair Value, Recurring [Member] \| Other Assets [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	9	9	10
Pepco Holdings LLC [Member] \| Fair Value, Recurring [Member] \| Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	144	144	140
Pepco Holdings LLC [Member] \| Fair Value, Recurring [Member] \| Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	59	59	55
Pepco Holdings LLC [Member] \| Fair Value, Recurring [Member] \| Mutual Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	14	14	14
Pepco Holdings LLC [Member] \| Fair Value, Recurring [Member] \| Fixed Income Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	11	11	11
Pepco Holdings LLC [Member] \| Fair Value, Recurring [Member] \| 6311 Life Insurance [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	60	60	60
Pepco Holdings LLC [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	46	46	86
Assets, Fair Value Disclosure	119	119	155
Deferred Compensation Liability, Current and Noncurrent	0	0	0
Total Liabilities	0	0	0
Fair Value, Net Asset (Liability)	119	119	155
Pepco Holdings LLC [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	73	73	69
Pepco Holdings LLC [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	59	59	55
Pepco Holdings LLC [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Mutual Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	14	14	14
Pepco Holdings LLC [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Fixed Income Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Pepco Holdings LLC [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| 6311 Life Insurance [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Pepco Holdings LLC [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	0	0	0
Assets, Fair Value Disclosure	37	37	37
Deferred Compensation Liability, Current and Noncurrent	(16)	(16)	(17)
Total Liabilities	(16)	(16)	(17)
Fair Value, Net Asset (Liability)	21	21	20
Pepco Holdings LLC [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	37	37	37
Pepco Holdings LLC [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Pepco Holdings LLC [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Mutual Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Pepco Holdings LLC [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Fixed Income Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	11	11	11
Pepco Holdings LLC [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| 6311 Life Insurance [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	26	26	26
Pepco Holdings LLC [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	0	0	0
Assets, Fair Value Disclosure	34	34	34
Deferred Compensation Liability, Current and Noncurrent	0	0	0
Total Liabilities	0	0	0
Fair Value, Net Asset (Liability)	34	34	34
Pepco Holdings LLC [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	34	34	34
Pepco Holdings LLC [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Pepco Holdings LLC [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Mutual Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Pepco Holdings LLC [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Fixed Income Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Pepco Holdings LLC [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| 6311 Life Insurance [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	34	34	34
Potomac Electric Power Company [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Unrealized Gain (Loss) on Investments	0	0
Potomac Electric Power Company [Member] \| Fair Value, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	28	28	35
Assets, Fair Value Disclosure	147	147	150
Deferred Compensation Liability, Current and Noncurrent	(2)	(2)	(2)
Total Liabilities	(2)	(2)	(2)
Fair Value, Net Asset (Liability)	145	145	148
Potomac Electric Power Company [Member] \| Fair Value, Recurring [Member] \| Cash and Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	17	17	30
Potomac Electric Power Company [Member] \| Fair Value, Recurring [Member] \| Restricted cash member [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	5	5	0
Potomac Electric Power Company [Member] \| Fair Value, Recurring [Member] \| Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	119	119	115
Potomac Electric Power Company [Member] \| Fair Value, Recurring [Member] \| Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	57	57	53
Potomac Electric Power Company [Member] \| Fair Value, Recurring [Member] \| Fixed Income Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	2	2	2
Potomac Electric Power Company [Member] \| Fair Value, Recurring [Member] \| 6311 Life Insurance [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	60	60	60
Potomac Electric Power Company [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	28	28	35
Assets, Fair Value Disclosure	85	85	88
Deferred Compensation Liability, Current and Noncurrent	0	0	0
Total Liabilities	0	0	0
Fair Value, Net Asset (Liability)	85	85	88
Potomac Electric Power Company [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	57	57	53
Potomac Electric Power Company [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	57	57	53
Potomac Electric Power Company [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Fixed Income Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Potomac Electric Power Company [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| 6311 Life Insurance [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Potomac Electric Power Company [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	0	0	0
Assets, Fair Value Disclosure	28	28	28
Deferred Compensation Liability, Current and Noncurrent	(2)	(2)	(2)
Total Liabilities	(2)	(2)	(2)
Fair Value, Net Asset (Liability)	26	26	26
Potomac Electric Power Company [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	28	28	28
Potomac Electric Power Company [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Potomac Electric Power Company [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Fixed Income Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	2	2	2
Potomac Electric Power Company [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| 6311 Life Insurance [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	26	26	26
Potomac Electric Power Company [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	0	0	0
Assets, Fair Value Disclosure	34	34	34
Deferred Compensation Liability, Current and Noncurrent	0	0	0
Total Liabilities	0	0	0
Fair Value, Net Asset (Liability)	34	34	34
Potomac Electric Power Company [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	34	34	34
Potomac Electric Power Company [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Potomac Electric Power Company [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Fixed Income Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Potomac Electric Power Company [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| 6311 Life Insurance [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	34	34	34
Delmarva Power and Light Company [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Unrealized Gain (Loss) on Investments	0	0
Delmarva Power and Light Company [Member] \| Fair Value, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	5	5	0
Assets, Fair Value Disclosure	5	5	0
Deferred Compensation Liability, Current and Noncurrent	0	0	0
Total Liabilities	0	0	0
Fair Value, Net Asset (Liability)	5	5	0
Delmarva Power and Light Company [Member] \| Fair Value, Recurring [Member] \| Cash and Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	17	17	15
Delmarva Power and Light Company [Member] \| Fair Value, Recurring [Member] \| Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Delmarva Power and Light Company [Member] \| Fair Value, Recurring [Member] \| Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Delmarva Power and Light Company [Member] \| Fair Value, Recurring [Member] \| Fixed Income Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Delmarva Power and Light Company [Member] \| Fair Value, Recurring [Member] \| 6311 Life Insurance [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Delmarva Power and Light Company [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	5	5	0
Assets, Fair Value Disclosure	5	5	0
Deferred Compensation Liability, Current and Noncurrent	0	0	0
Total Liabilities	0	0	0
Fair Value, Net Asset (Liability)	5	5	0
Delmarva Power and Light Company [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Delmarva Power and Light Company [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Delmarva Power and Light Company [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Fixed Income Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Delmarva Power and Light Company [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| 6311 Life Insurance [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Delmarva Power and Light Company [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	0	0	0
Assets, Fair Value Disclosure	0	0	0
Deferred Compensation Liability, Current and Noncurrent	0	0	0
Total Liabilities	0	0	0
Fair Value, Net Asset (Liability)	0	0	0
Delmarva Power and Light Company [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Delmarva Power and Light Company [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Delmarva Power and Light Company [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Fixed Income Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Delmarva Power and Light Company [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| 6311 Life Insurance [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Delmarva Power and Light Company [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	0	0	0
Assets, Fair Value Disclosure	0	0	0
Deferred Compensation Liability, Current and Noncurrent	0	0	0
Total Liabilities	0	0	0
Fair Value, Net Asset (Liability)	0	0	0
Delmarva Power and Light Company [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Delmarva Power and Light Company [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Delmarva Power and Light Company [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Fixed Income Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Delmarva Power and Light Company [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| 6311 Life Insurance [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Atlantic City Electric Company [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Unrealized Gain (Loss) on Investments	0	0
Atlantic City Electric Company [Member] \| Fair Value, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	12	12	13
Assets, Fair Value Disclosure	12	12	13
Deferred Compensation Liability, Current and Noncurrent	0	0	0
Total Liabilities	0	0	0
Fair Value, Net Asset (Liability)	12	12	13
Atlantic City Electric Company [Member] \| Fair Value, Recurring [Member] \| Cash and Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	11	11	17
Atlantic City Electric Company [Member] \| Fair Value, Recurring [Member] \| Other Assets [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	9	9	10
Atlantic City Electric Company [Member] \| Fair Value, Recurring [Member] \| Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Atlantic City Electric Company [Member] \| Fair Value, Recurring [Member] \| Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Atlantic City Electric Company [Member] \| Fair Value, Recurring [Member] \| Fixed Income Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Atlantic City Electric Company [Member] \| Fair Value, Recurring [Member] \| 6311 Life Insurance [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Atlantic City Electric Company [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	12	12	13
Assets, Fair Value Disclosure	12	12	13
Deferred Compensation Liability, Current and Noncurrent	0	0	0
Total Liabilities	0	0	0
Fair Value, Net Asset (Liability)	12	12	13
Atlantic City Electric Company [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Atlantic City Electric Company [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Atlantic City Electric Company [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Fixed Income Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Atlantic City Electric Company [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| 6311 Life Insurance [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Atlantic City Electric Company [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	0	0	0
Assets, Fair Value Disclosure	0	0	0
Deferred Compensation Liability, Current and Noncurrent	0	0	0
Total Liabilities	0	0	0
Fair Value, Net Asset (Liability)	0	0	0
Atlantic City Electric Company [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Atlantic City Electric Company [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Atlantic City Electric Company [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Fixed Income Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Atlantic City Electric Company [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| 6311 Life Insurance [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Atlantic City Electric Company [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	0	0	0
Assets, Fair Value Disclosure	0	0	0
Deferred Compensation Liability, Current and Noncurrent	0	0	0
Total Liabilities	0	0	0
Fair Value, Net Asset (Liability)	0	0	0
Atlantic City Electric Company [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Atlantic City Electric Company [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Atlantic City Electric Company [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Fixed Income Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Atlantic City Electric Company [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| 6311 Life Insurance [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0	0
Exelon Generation Co LLC Affiliate [Member] \| Fair Value, Recurring [Member] \| Nuclear Decommissioning Trust Fund Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Financial Instruments Sold, Not yet Purchased, Corporate Debt	(52)	(52)	(62)
Maturity Less than 30 Days [Member] \| Fair Value, Recurring [Member] \| Nuclear Decommissioning Trust Fund Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative, Collateral, Right to Reclaim Cash	103	103	116
Maturity Less than 30 Days [Member] \| Exelon Generation Co L L C [Member] \| Fair Value, Recurring [Member] \| Nuclear Decommissioning Trust Fund Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative, Collateral, Right to Reclaim Cash	$ 103	$ 103	$ 116

Fair Value of Financial Asset_6

Fair Value of Financial Assets and Liabilities - Fair Value Assets Liabilities Measured On Recurring Basis Unobservable Input Reconciliation (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Fair Value, Inputs, Level 3 [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Beginning Balance	$ 426	$ 1,088	$ 660	$ 1,068
Total realized / unrealized gains (losses)
Included in net income	(357)	(166)	(632)	(156)
Included in noncurrent payables to affiliates	0		0	0
Included in regulatory assets	36	(4)	43	(18)
Change in collateral	(282)	(42)	(338)	(41)
Purchases, sales, issuances and settlements
Purchases	7	30	115	71
Sales	1	(2)	1	(24)
Settlements	(28)	(1)	(48)	(15)
Transfers into Level 3	1	(9)	1	(6)
Transfers out of Level 3	(39)	(11)	(37)	4
Ending Balance	(235)	883	(235)	883
Fair Value, Asset, Recurring Basis, Still Held, Unrealized Gain (Loss)	(372)	(72)	(518)	115
Fair Value, Inputs, Level 3 [Member] \| Consolidation, Eliminations [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Beginning Balance	0	0	0	0
Total realized / unrealized gains (losses)
Included in net income	0	0	0	0
Included in noncurrent payables to affiliates	(6)		(7)	1
Included in regulatory assets	6	0	7	(1)
Change in collateral	0	0	0	0
Purchases, sales, issuances and settlements
Purchases	0	0	0	0
Sales	0	0	0	0
Settlements	0	0	0	0
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Ending Balance	0	0	0	0
Fair Value, Asset, Recurring Basis, Still Held, Unrealized Gain (Loss)	0	0	0	0
Exelon Generation Co L L C [Member]
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Abstract]
Fair Value, Assets and Liabilities Measured on Recurring Basis, Gain (Loss) Included in Earnings	15	94	(114)	271
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 3 [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Beginning Balance	686	1,360	927	1,328
Total realized / unrealized gains (losses)
Included in net income	(358)	(167)	(634)	(158)
Included in noncurrent payables to affiliates	6		7	(1)
Included in regulatory assets	0	0	0	0
Change in collateral	(282)	(42)	(338)	(41)
Purchases, sales, issuances and settlements
Purchases	7	30	115	71
Sales	1	(2)	1	(24)
Settlements	(26)	(1)	(46)	(15)
Transfers into Level 3	1	(9)	1	(6)
Transfers out of Level 3	(39)	(11)	(37)	4
Ending Balance	(4)	1,158	(4)	1,158
Fair Value, Asset, Recurring Basis, Still Held, Unrealized Gain (Loss)	(373)	(73)	(520)	113
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 3 [Member] \| Nuclear Decommissioning Trust Fund Investments [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Beginning Balance	479	498	497	511
Total realized / unrealized gains (losses)
Included in net income	1	(1)	2	(2)
Included in noncurrent payables to affiliates	6		7	(1)
Included in regulatory assets	0	0	0	0
Change in collateral	0	0	0	0
Purchases, sales, issuances and settlements
Purchases	1	3	1	6
Sales	0	0	0	0
Settlements	(26)	(1)	(46)	(15)
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Ending Balance	461	499	461	499
Fair Value, Asset, Recurring Basis, Still Held, Unrealized Gain (Loss)	1	(1)	2	(2)
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 3 [Member] \| Derivative [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Beginning Balance	207	862	430	817
Total realized / unrealized gains (losses)
Included in net income	(359)	(166)	(636)	(156)
Included in noncurrent payables to affiliates	0		0	0
Included in regulatory assets	0	0	0	0
Change in collateral	(282)	(42)	(338)	(41)
Purchases, sales, issuances and settlements
Purchases	6	27	114	65
Sales	1	(2)	1	(24)
Settlements	0	0	0	0
Transfers into Level 3	1	(9)	1	(6)
Transfers out of Level 3	(39)	(11)	(37)	4
Ending Balance	(465)	659	(465)	659
Fair Value, Asset, Recurring Basis, Still Held, Unrealized Gain (Loss)	(374)	(72)	(522)	115
Commonwealth Edison Co [Member] \| Derivative [Member] \| Interest Rate Swap [Member]
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Abstract]
Realized Investment Gains (Losses)	5	8	13	18
Commonwealth Edison Co [Member] \| Fair Value, Inputs, Level 3 [Member] \| Derivative [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Beginning Balance	(295)	(314)	(301)	(301)
Total realized / unrealized gains (losses)
Included in net income	0	0	0	0
Included in noncurrent payables to affiliates	0		0	0
Included in regulatory assets	30	(4)	36	(17)
Change in collateral	0	0	0	0
Purchases, sales, issuances and settlements
Purchases	0	0	0	0
Sales	0	0	0	0
Settlements	0	0	0	0
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Ending Balance	(265)	(318)	(265)	(318)
Fair Value, Asset, Recurring Basis, Still Held, Unrealized Gain (Loss)	0	0	0	0
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Abstract]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Period Increase (Decrease)	(25)	(12)	(23)	(35)
Pepco Holdings LLC [Member] \| Fair Value, Inputs, Level 3 [Member] \| 6311 Life Insurance [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Beginning Balance	35	42	34	41
Total realized / unrealized gains (losses)
Included in net income	1	1	2	2
Included in noncurrent payables to affiliates	0		0	0
Included in regulatory assets	0	0	0	0
Change in collateral	0	0	0	0
Purchases, sales, issuances and settlements
Purchases	0	0	0	0
Sales	0	0	0	0
Settlements	(2)	0	(2)	0
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Ending Balance	34	43	34	43
Fair Value, Asset, Recurring Basis, Still Held, Unrealized Gain (Loss)	1	1		2
Potomac Electric Power Company [Member] \| Fair Value, Inputs, Level 3 [Member] \| 6311 Life Insurance [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Beginning Balance	35	42	34	41
Total realized / unrealized gains (losses)
Included in net income	1	1	2	2
Included in noncurrent payables to affiliates	0		0	0
Included in regulatory assets	0	0	0	0
Change in collateral	0	0	0	0
Purchases, sales, issuances and settlements
Purchases	0	0	0	0
Sales	0	0	0	0
Settlements	(2)	0	(2)	0
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Ending Balance	34	43	$ 34	43
Fair Value, Asset, Recurring Basis, Still Held, Unrealized Gain (Loss)	$ 1	$ 1		$ 2

Fair Value of Financial Asset_7

Fair Value of Financial Assets and Liabilities - Fair Value Assets And Liabilities Measured On Recurring Basis Gain Loss Included In Earnings (Details) - Fair Value, Inputs, Level 3 [Member] - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Fair Value Assets And Liabilities Measured On Recurring Basis Gain Loss Included In Earnings [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings	$ 357	$ 166	$ 632	$ 156
Fair Value, Asset, Recurring Basis, Still Held, Unrealized Gain (Loss)	(372)	(72)	(518)	115
Operating Revenue [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Gain Loss Included In Earnings [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings	(555)	(137)	(670)	(65)
Fair Value, Asset, Recurring Basis, Still Held, Unrealized Gain (Loss)	(543)	(39)	(608)	166
Purchased Power And Fuel [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Gain Loss Included In Earnings [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings	196	(29)	34	(91)
Fair Value, Asset, Recurring Basis, Still Held, Unrealized Gain (Loss)	169	(33)	86	(51)
Operating and Maintenance [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Gain Loss Included In Earnings [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings	1	1	2	2
Fair Value, Asset, Recurring Basis, Still Held, Unrealized Gain (Loss)	1	1	2	2
Other, net [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Gain Loss Included In Earnings [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings	1	0	2	0
Fair Value, Asset, Recurring Basis, Still Held, Unrealized Gain (Loss)	1	(1)	2	(2)
Exelon Generation Co L L C [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Gain Loss Included In Earnings [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings	358	167	634	158
Fair Value, Asset, Recurring Basis, Still Held, Unrealized Gain (Loss)	(373)	(73)	(520)	113
Exelon Generation Co L L C [Member] \| Operating Revenue [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Gain Loss Included In Earnings [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings	(555)	(137)	(670)	(65)
Fair Value, Asset, Recurring Basis, Still Held, Unrealized Gain (Loss)	(543)	(39)	(608)	166
Exelon Generation Co L L C [Member] \| Purchased Power And Fuel [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Gain Loss Included In Earnings [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings	196	(29)	34	(91)
Fair Value, Asset, Recurring Basis, Still Held, Unrealized Gain (Loss)	169	(33)	86	(51)
Exelon Generation Co L L C [Member] \| Other, net [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Gain Loss Included In Earnings [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings	1	0	2	0
Fair Value, Asset, Recurring Basis, Still Held, Unrealized Gain (Loss)	1	(1)	2	(2)
Pepco Holdings LLC [Member] \| Operating and Maintenance [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Gain Loss Included In Earnings [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings	1	1	2	2
Fair Value, Asset, Recurring Basis, Still Held, Unrealized Gain (Loss)	1	1	2	2
Potomac Electric Power Company [Member] \| Operating and Maintenance [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Gain Loss Included In Earnings [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings	1	1	2	2
Fair Value, Asset, Recurring Basis, Still Held, Unrealized Gain (Loss)	$ 1	$ 1	$ 2	$ 2

Fair Value of Financial Asset_8

Fair Value of Financial Assets and Liabilities - Fair Value Inputs Assets Quantitative Information (Details)	6 Months Ended	12 Months Ended
	Jun. 30, 2021USD ($)	Dec. 31, 2020USD ($)
Fair Value, Inputs, Level 3 [Member]
Derivatives Fair Value Footnotes [Abstract]
Cash Collateral Posted	$ (176,000,000)	$ 162,000,000
Fair Value, Inputs, Level 3 [Member] \| Economic Hedges [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	(285,000,000)	245,000,000
Fair Value, Inputs, Level 3 [Member] \| Derivative [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	$ (265,000,000)	$ (301,000,000)
Fair Value, Inputs, Level 3 [Member] \| Derivative [Member] \| Discounted Cash Flow [Member] \| Minimum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Abstract]
Forward power price assets	7.13	2.25
Forward gas price assets	1.53	1.57
Derivative Asset (Liability) Net, Measurement Input	0.03	0.03
Forward heat rate	900.00%	800.00%
Fair Value Inputs Renewable Factor	94.00%	91.00%
Fair Value, Inputs, Level 3 [Member] \| Derivative [Member] \| Discounted Cash Flow [Member] \| Maximum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Abstract]
Forward power price assets	281	163
Forward gas price assets	12.51	7.88
Derivative Asset (Liability) Net, Measurement Input	0.07	0.08
Forward heat rate	1000.00%	900.00%
Fair Value Inputs Renewable Factor	122.00%	123.00%
Fair Value, Inputs, Level 3 [Member] \| Derivative [Member] \| Discounted Cash Flow [Member] \| Arithmetic Average [Member]
Fair Value Measurement Inputs and Valuation Techniques [Abstract]
Forward power price assets	39	30
Forward gas price assets	3.10	2.59
Derivative Asset (Liability) Net, Measurement Input	0.0477	0.0493
Forward heat rate	913.00%	885.00%
Fair Value Inputs Renewable Factor	99.00%	99.00%
Fair Value, Inputs, Level 3 [Member] \| Derivative [Member] \| Option Model Valuation Technique [Member] \| Minimum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Abstract]
Derivative Asset (Liability) Net, Measurement Input	0.11	0.11
Fair Value, Inputs, Level 3 [Member] \| Derivative [Member] \| Option Model Valuation Technique [Member] \| Maximum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Abstract]
Derivative Asset (Liability) Net, Measurement Input	2.09	2.37
Fair Value, Inputs, Level 3 [Member] \| Derivative [Member] \| Option Model Valuation Technique [Member] \| Arithmetic Average [Member]
Fair Value Measurement Inputs and Valuation Techniques [Abstract]
Derivative Asset (Liability) Net, Measurement Input	0.33	0.32
Fair Value, Inputs, Level 3 [Member] \| Proprietary Trading [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	$ (4,000,000)	$ 23,000,000
Fair Value, Inputs, Level 3 [Member] \| Proprietary Trading [Member] \| Discounted Cash Flow [Member] \| Minimum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Abstract]
Forward power price assets	10	10
Fair Value, Inputs, Level 3 [Member] \| Proprietary Trading [Member] \| Discounted Cash Flow [Member] \| Maximum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Abstract]
Forward power price assets	132	106
Fair Value, Inputs, Level 3 [Member] \| Proprietary Trading [Member] \| Discounted Cash Flow [Member] \| Arithmetic Average [Member]
Fair Value Measurement Inputs and Valuation Techniques [Abstract]
Forward power price assets	38	27
Exelon Generation Co L L C [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	$ 1,022,000,000	$ 297,000,000
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 3 [Member]
Derivatives Fair Value Footnotes [Abstract]
Cash Collateral Posted	(176,000,000)	162,000,000
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 3 [Member] \| Economic Hedges [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	$ (285,000,000)	$ 245,000,000
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 3 [Member] \| Derivative [Member] \| Discounted Cash Flow [Member] \| Minimum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Abstract]
Forward power price assets	7.13	2.25
Forward gas price assets	1.53	1.57
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 3 [Member] \| Derivative [Member] \| Discounted Cash Flow [Member] \| Maximum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Abstract]
Forward power price assets	281	163
Forward gas price assets	12.51	7.88
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 3 [Member] \| Derivative [Member] \| Discounted Cash Flow [Member] \| Arithmetic Average [Member]
Fair Value Measurement Inputs and Valuation Techniques [Abstract]
Forward power price assets	39	30
Forward gas price assets	3.10	2.59
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 3 [Member] \| Derivative [Member] \| Option Model Valuation Technique [Member] \| Minimum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Abstract]
Derivative Asset (Liability) Net, Measurement Input	0.11	0.11
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 3 [Member] \| Derivative [Member] \| Option Model Valuation Technique [Member] \| Maximum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Abstract]
Derivative Asset (Liability) Net, Measurement Input	2.09	2.37
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 3 [Member] \| Derivative [Member] \| Option Model Valuation Technique [Member] \| Arithmetic Average [Member]
Fair Value Measurement Inputs and Valuation Techniques [Abstract]
Derivative Asset (Liability) Net, Measurement Input	0.33	0.32
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 3 [Member] \| Proprietary Trading [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	$ (4,000,000)	$ 23,000,000
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 3 [Member] \| Proprietary Trading [Member] \| Discounted Cash Flow [Member] \| Minimum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Abstract]
Forward power price assets	10	10
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 3 [Member] \| Proprietary Trading [Member] \| Discounted Cash Flow [Member] \| Maximum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Abstract]
Forward power price assets	132	106
Exelon Generation Co L L C [Member] \| Fair Value, Inputs, Level 3 [Member] \| Proprietary Trading [Member] \| Discounted Cash Flow [Member] \| Arithmetic Average [Member]
Fair Value Measurement Inputs and Valuation Techniques [Abstract]
Forward power price assets	38	27
Commonwealth Edison Co [Member] \| Fair Value, Inputs, Level 3 [Member] \| Derivative [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	$ (265,000,000)	$ (301,000,000)
Commonwealth Edison Co [Member] \| Fair Value, Inputs, Level 3 [Member] \| Derivative [Member] \| Discounted Cash Flow [Member] \| Minimum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Abstract]
Derivative Asset (Liability) Net, Measurement Input	0.03	0.03
Forward heat rate	900.00%	800.00%
Fair Value Inputs Renewable Factor	94.00%	91.00%
Commonwealth Edison Co [Member] \| Fair Value, Inputs, Level 3 [Member] \| Derivative [Member] \| Discounted Cash Flow [Member] \| Maximum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Abstract]
Derivative Asset (Liability) Net, Measurement Input	0.07	0.08
Forward heat rate	1000.00%	900.00%
Fair Value Inputs Renewable Factor	122.00%	123.00%
Commonwealth Edison Co [Member] \| Fair Value, Inputs, Level 3 [Member] \| Derivative [Member] \| Discounted Cash Flow [Member] \| Arithmetic Average [Member]
Fair Value Measurement Inputs and Valuation Techniques [Abstract]
Derivative Asset (Liability) Net, Measurement Input	0.0477	0.0493
Forward heat rate	913.00%	885.00%
Fair Value Inputs Renewable Factor	99.00%	99.00%

Commitments and Contingencies -

Commitments and Contingencies - Narrative (Details) $ in Millions	Mar. 23, 2016USD ($)MW	Jun. 30, 2021USD ($)MGPSiteOpen_claimMW	Dec. 31, 2022MW	Dec. 31, 2020USD ($)	Dec. 31, 2018MW	Dec. 31, 2017MW	Mar. 31, 2021USD ($)
Commitments And Contingencies Additional Narrative Information [Line Items]
Other Commitment		$ 3,079
Accrual for Environmental Loss Contingencies, Gross		461		$ 483
Liability for Asbestos and Environmental Claims, Gross		85		89
Exelon Generation Co L L C [Member]
Commitments And Contingencies Additional Narrative Information [Line Items]
Other Commitment		2,507
Accrual for Environmental Loss Contingencies, Gross		117		121
Liability for Asbestos and Environmental Claims, Gross		85		89
Exelon Generation Co L L C [Member] \| LDC Damages
Commitments And Contingencies Additional Narrative Information [Line Items]
LDC Damages							$ 40
Exelon Generation Co L L C [Member] \| LDC Damages - Accrued Liability
Commitments And Contingencies Additional Narrative Information [Line Items]
LDC Damages		40
Commonwealth Edison Co [Member]
Commitments And Contingencies Additional Narrative Information [Line Items]
Other Commitment		$ 224
Mgp Site Contingency Monitoring Count \| MGPSite		21
Accrual for Environmental Loss Contingencies, Gross		$ 273		293
Deferred Prosecution Agreement Payments				200
PECO Energy Co [Member]
Commitments And Contingencies Additional Narrative Information [Line Items]
Other Commitment		$ 181
Mgp Site Contingency Monitoring Count \| MGPSite		7
Accrual for Environmental Loss Contingencies, Gross		$ 22		23
Baltimore Gas and Electric Company [Member]
Commitments And Contingencies Additional Narrative Information [Line Items]
Other Commitment		$ 5
Mgp Site Contingency Monitoring Count \| MGPSite		4
Accrual for Environmental Loss Contingencies, Gross		$ 6		2
Pepco Holdings LLC [Member]
Commitments And Contingencies Additional Narrative Information [Line Items]
Other Commitment		55
Accrual for Environmental Loss Contingencies, Gross		43		44
Potomac Electric Power Company [Member]
Commitments And Contingencies Additional Narrative Information [Line Items]
Other Commitment		27
Accrual for Environmental Loss Contingencies, Gross		41		42
Delmarva Power and Light Company [Member]
Commitments And Contingencies Additional Narrative Information [Line Items]
Other Commitment		$ 17
Mgp Site Contingency Count \| MGPSite		1
Accrual for Environmental Loss Contingencies, Gross		$ 1		$ 1
Open Claims [Member] \| Exelon Generation Co L L C [Member]
Commitments And Contingencies Additional Narrative Information [Line Items]
Liability for Asbestos and Environmental Claims, Gross		$ 21
Open Asbestos Related Personal Injury Claims \| Open_claim		230
Estimated Future Claims [Member] \| Exelon Generation Co L L C [Member]
Commitments And Contingencies Additional Narrative Information [Line Items]
Liability for Asbestos and Environmental Claims, Gross		$ 64
Pepco Holdings Inc [Member]
Commitments And Contingencies Additional Narrative Information [Line Items]
Other Commitment		513
Pepco Holdings Inc [Member] \| Pepco Holdings LLC [Member]
Commitments And Contingencies Additional Narrative Information [Line Items]
Other Commitment		320
Pepco Holdings Inc [Member] \| Potomac Electric Power Company [Member]
Commitments And Contingencies Additional Narrative Information [Line Items]
Other Commitment		120
Pepco Holdings Inc [Member] \| Delmarva Power and Light Company [Member]
Commitments And Contingencies Additional Narrative Information [Line Items]
Other Commitment		89
West Lake [Member]
Commitments And Contingencies Additional Narrative Information [Line Items]
Accrual for Environmental Loss Contingencies, Gross		280
West Lake [Member] \| Exelon Generation Co L L C [Member]
Commitments And Contingencies Additional Narrative Information [Line Items]
Accrual for Environmental Loss Contingencies, Gross		30
Accrual for Environmental Loss Contingencies, Component Amount		90
Other Solar Projects [Member] \| Pepco Holdings Inc [Member]
Commitments And Contingencies Additional Narrative Information [Line Items]
Business Acquisition, Expected New Generation Mwh \| MW	37
Other Commitment	$ 135	$ 121
Other Non-Financial Commitment \| MW		33
Other Solar Projects [Member] \| Pepco Holdings Inc [Member] \| Exelon Generation Co L L C [Member]
Commitments And Contingencies Additional Narrative Information [Line Items]
Other Commitment		$ 121
Wind Assets [Member] \| Pepco Holdings Inc [Member]
Commitments And Contingencies Additional Narrative Information [Line Items]
Other Non-Financial Commitment \| MW	100
Wind Assets [Member] \| Pepco Holdings Inc [Member] \| Delmarva Power and Light Company [Member]
Commitments And Contingencies Additional Narrative Information [Line Items]
Purchase Commitment \| MW	120		40		40	40

Commitments and Contingencies_3

Commitments and Contingencies - Merger Commitment (Details) $ in Millions	Jun. 30, 2021USD ($)
Other Commitments [Line Items]
Other Commitment	$ 3,079
Pepco Holdings LLC [Member]
Other Commitments [Line Items]
Other Commitment	55
Potomac Electric Power Company [Member]
Other Commitments [Line Items]
Other Commitment	27
Delmarva Power and Light Company [Member]
Other Commitments [Line Items]
Other Commitment	17
Atlantic City Electric Company [Member]
Other Commitments [Line Items]
Other Commitment	11
Pepco Holdings Inc [Member]
Other Commitments [Line Items]
Other Commitment	513
Pepco Holdings Inc [Member] \| Remaining commitment
Other Commitments [Line Items]
Other Commitment	76
Pepco Holdings Inc [Member] \| Pepco Holdings LLC [Member]
Other Commitments [Line Items]
Other Commitment	320
Pepco Holdings Inc [Member] \| Pepco Holdings LLC [Member] \| Remaining commitment
Other Commitments [Line Items]
Other Commitment	63
Pepco Holdings Inc [Member] \| Potomac Electric Power Company [Member]
Other Commitments [Line Items]
Other Commitment	120
Pepco Holdings Inc [Member] \| Potomac Electric Power Company [Member] \| Remaining commitment
Other Commitments [Line Items]
Other Commitment	52
Pepco Holdings Inc [Member] \| Delmarva Power and Light Company [Member]
Other Commitments [Line Items]
Other Commitment	89
Pepco Holdings Inc [Member] \| Delmarva Power and Light Company [Member] \| Remaining commitment
Other Commitments [Line Items]
Other Commitment	7
Pepco Holdings Inc [Member] \| Atlantic City Electric Company [Member]
Other Commitments [Line Items]
Other Commitment	111
Pepco Holdings Inc [Member] \| Atlantic City Electric Company [Member] \| Remaining commitment
Other Commitments [Line Items]
Other Commitment	$ 4

Commitments and Contingencies_4

Commitments and Contingencies - Schedule of Commercial Commitments (Details) $ in Millions	Jun. 30, 2021USD ($)
Other Commitments [Line Items]
Other Commitment	$ 3,079
Other Commitment, to be Paid, Remainder of Fiscal Year	1,210
Other Commitment, to be Paid, Year One	1,462
Other Commitment, to be Paid, Year Two	3
Other Commitment, to be Paid, Year Three	8
Other Commitment, to be Paid, Year Four	6
Other Commitment, to be Paid, Year Five and Beyond	390
Guarantor Obligations, Maximum Exposure, Undiscounted	75
Letters of Credit
Other Commitments [Line Items]
Other Commitment	1,751
Other Commitment, to be Paid, Remainder of Fiscal Year	591
Other Commitment, to be Paid, Year One	1,160
Other Commitment, to be Paid, Year Two	0
Other Commitment, to be Paid, Year Three	0
Other Commitment, to be Paid, Year Four	0
Other Commitment, to be Paid, Year Five and Beyond	0
Surety Bonds
Other Commitments [Line Items]
Other Commitment	920
Other Commitment, to be Paid, Remainder of Fiscal Year	619
Other Commitment, to be Paid, Year One	299
Other Commitment, to be Paid, Year Two	0
Other Commitment, to be Paid, Year Three	2
Other Commitment, to be Paid, Year Four	0
Other Commitment, to be Paid, Year Five and Beyond	0
Financing trust guarantees
Other Commitments [Line Items]
Other Commitment	378
Other Commitment, to be Paid, Remainder of Fiscal Year	0
Other Commitment, to be Paid, Year One	0
Other Commitment, to be Paid, Year Two	0
Other Commitment, to be Paid, Year Three	0
Other Commitment, to be Paid, Year Four	0
Other Commitment, to be Paid, Year Five and Beyond	378
Guaranteed lease residual values
Other Commitments [Line Items]
Other Commitment	30
Other Commitment, to be Paid, Remainder of Fiscal Year	0
Other Commitment, to be Paid, Year One	3
Other Commitment, to be Paid, Year Two	3
Other Commitment, to be Paid, Year Three	6
Other Commitment, to be Paid, Year Four	6
Other Commitment, to be Paid, Year Five and Beyond	12
Exelon Generation Co L L C [Member]
Other Commitments [Line Items]
Other Commitment	2,507
Other Commitment, to be Paid, Remainder of Fiscal Year	1,092
Other Commitment, to be Paid, Year One	1,415
Other Commitment, to be Paid, Year Two	0
Other Commitment, to be Paid, Year Three	0
Other Commitment, to be Paid, Year Four	0
Other Commitment, to be Paid, Year Five and Beyond	0
Exelon Generation Co L L C [Member] \| Letters of Credit
Other Commitments [Line Items]
Other Commitment	1,735
Other Commitment, to be Paid, Remainder of Fiscal Year	578
Other Commitment, to be Paid, Year One	1,157
Other Commitment, to be Paid, Year Two	0
Other Commitment, to be Paid, Year Three	0
Other Commitment, to be Paid, Year Four	0
Other Commitment, to be Paid, Year Five and Beyond	0
Exelon Generation Co L L C [Member] \| Surety Bonds
Other Commitments [Line Items]
Other Commitment	772
Other Commitment, to be Paid, Remainder of Fiscal Year	514
Other Commitment, to be Paid, Year One	258
Other Commitment, to be Paid, Year Two	0
Other Commitment, to be Paid, Year Three	0
Other Commitment, to be Paid, Year Four	0
Other Commitment, to be Paid, Year Five and Beyond	0
Commonwealth Edison Co [Member]
Other Commitments [Line Items]
Other Commitment	224
Other Commitment, to be Paid, Remainder of Fiscal Year	16
Other Commitment, to be Paid, Year One	6
Other Commitment, to be Paid, Year Two	0
Other Commitment, to be Paid, Year Three	2
Other Commitment, to be Paid, Year Four	0
Other Commitment, to be Paid, Year Five and Beyond	200
Commonwealth Edison Co [Member] \| Letters of Credit
Other Commitments [Line Items]
Other Commitment	7
Other Commitment, to be Paid, Remainder of Fiscal Year	7
Other Commitment, to be Paid, Year One	0
Other Commitment, to be Paid, Year Two	0
Other Commitment, to be Paid, Year Three	0
Other Commitment, to be Paid, Year Four	0
Other Commitment, to be Paid, Year Five and Beyond	0
Commonwealth Edison Co [Member] \| Surety Bonds
Other Commitments [Line Items]
Other Commitment	17
Other Commitment, to be Paid, Remainder of Fiscal Year	9
Other Commitment, to be Paid, Year One	6
Other Commitment, to be Paid, Year Two	0
Other Commitment, to be Paid, Year Three	2
Other Commitment, to be Paid, Year Four	0
Other Commitment, to be Paid, Year Five and Beyond	0
Commonwealth Edison Co [Member] \| Financing trust guarantees
Other Commitments [Line Items]
Other Commitment	200
Other Commitment, to be Paid, Remainder of Fiscal Year	0
Other Commitment, to be Paid, Year One	0
Other Commitment, to be Paid, Year Two	0
Other Commitment, to be Paid, Year Three	0
Other Commitment, to be Paid, Year Four	0
Other Commitment, to be Paid, Year Five and Beyond	200
PECO Energy Co [Member]
Other Commitments [Line Items]
Other Commitment	181
Other Commitment, to be Paid, Remainder of Fiscal Year	1
Other Commitment, to be Paid, Year One	2
Other Commitment, to be Paid, Year Two	0
Other Commitment, to be Paid, Year Three	0
Other Commitment, to be Paid, Year Four	0
Other Commitment, to be Paid, Year Five and Beyond	178
PECO Energy Co [Member] \| Surety Bonds
Other Commitments [Line Items]
Other Commitment	3
Other Commitment, to be Paid, Remainder of Fiscal Year	1
Other Commitment, to be Paid, Year One	2
Other Commitment, to be Paid, Year Two	0
Other Commitment, to be Paid, Year Three	0
Other Commitment, to be Paid, Year Four	0
Other Commitment, to be Paid, Year Five and Beyond	0
PECO Energy Co [Member] \| Financing trust guarantees
Other Commitments [Line Items]
Other Commitment	178
Other Commitment, to be Paid, Remainder of Fiscal Year	0
Other Commitment, to be Paid, Year One	0
Other Commitment, to be Paid, Year Two	0
Other Commitment, to be Paid, Year Three	0
Other Commitment, to be Paid, Year Four	0
Other Commitment, to be Paid, Year Five and Beyond	178
Baltimore Gas and Electric Company [Member]
Other Commitments [Line Items]
Other Commitment	5
Other Commitment, to be Paid, Remainder of Fiscal Year	2
Other Commitment, to be Paid, Year One	3
Other Commitment, to be Paid, Year Two	0
Other Commitment, to be Paid, Year Three	0
Other Commitment, to be Paid, Year Four	0
Other Commitment, to be Paid, Year Five and Beyond	0
Baltimore Gas and Electric Company [Member] \| Letters of Credit
Other Commitments [Line Items]
Other Commitment	2
Other Commitment, to be Paid, Remainder of Fiscal Year	0
Other Commitment, to be Paid, Year One	2
Other Commitment, to be Paid, Year Two	0
Other Commitment, to be Paid, Year Three	0
Other Commitment, to be Paid, Year Four	0
Other Commitment, to be Paid, Year Five and Beyond	0
Baltimore Gas and Electric Company [Member] \| Surety Bonds
Other Commitments [Line Items]
Other Commitment	3
Other Commitment, to be Paid, Remainder of Fiscal Year	2
Other Commitment, to be Paid, Year One	1
Other Commitment, to be Paid, Year Two	0
Other Commitment, to be Paid, Year Three	0
Other Commitment, to be Paid, Year Four	0
Other Commitment, to be Paid, Year Five and Beyond	0
Pepco Holdings LLC [Member]
Other Commitments [Line Items]
Other Commitment	55
Other Commitment, to be Paid, Remainder of Fiscal Year	8
Other Commitment, to be Paid, Year One	20
Other Commitment, to be Paid, Year Two	3
Other Commitment, to be Paid, Year Three	6
Other Commitment, to be Paid, Year Four	6
Other Commitment, to be Paid, Year Five and Beyond	12
Guarantor Obligations, Maximum Exposure, Undiscounted	75
Pepco Holdings LLC [Member] \| Surety Bonds
Other Commitments [Line Items]
Other Commitment	25
Other Commitment, to be Paid, Remainder of Fiscal Year	8
Other Commitment, to be Paid, Year One	17
Other Commitment, to be Paid, Year Two	0
Other Commitment, to be Paid, Year Three	0
Other Commitment, to be Paid, Year Four	0
Other Commitment, to be Paid, Year Five and Beyond	0
Pepco Holdings LLC [Member] \| Guaranteed lease residual values
Other Commitments [Line Items]
Other Commitment	30
Other Commitment, to be Paid, Remainder of Fiscal Year	0
Other Commitment, to be Paid, Year One	3
Other Commitment, to be Paid, Year Two	3
Other Commitment, to be Paid, Year Three	6
Other Commitment, to be Paid, Year Four	6
Other Commitment, to be Paid, Year Five and Beyond	12
Potomac Electric Power Company [Member]
Other Commitments [Line Items]
Other Commitment	27
Other Commitment, to be Paid, Remainder of Fiscal Year	4
Other Commitment, to be Paid, Year One	14
Other Commitment, to be Paid, Year Two	1
Other Commitment, to be Paid, Year Three	2
Other Commitment, to be Paid, Year Four	2
Other Commitment, to be Paid, Year Five and Beyond	4
Guarantor Obligations, Maximum Exposure, Undiscounted	26
Potomac Electric Power Company [Member] \| Surety Bonds
Other Commitments [Line Items]
Other Commitment	17
Other Commitment, to be Paid, Remainder of Fiscal Year	4
Other Commitment, to be Paid, Year One	13
Other Commitment, to be Paid, Year Two	0
Other Commitment, to be Paid, Year Three	0
Other Commitment, to be Paid, Year Four	0
Other Commitment, to be Paid, Year Five and Beyond	0
Potomac Electric Power Company [Member] \| Guaranteed lease residual values
Other Commitments [Line Items]
Other Commitment	10
Other Commitment, to be Paid, Remainder of Fiscal Year	0
Other Commitment, to be Paid, Year One	1
Other Commitment, to be Paid, Year Two	1
Other Commitment, to be Paid, Year Three	2
Other Commitment, to be Paid, Year Four	2
Other Commitment, to be Paid, Year Five and Beyond	4
Delmarva Power and Light Company [Member]
Other Commitments [Line Items]
Other Commitment	17
Other Commitment, to be Paid, Remainder of Fiscal Year	2
Other Commitment, to be Paid, Year One	3
Other Commitment, to be Paid, Year Two	1
Other Commitment, to be Paid, Year Three	3
Other Commitment, to be Paid, Year Four	3
Other Commitment, to be Paid, Year Five and Beyond	5
Guarantor Obligations, Maximum Exposure, Undiscounted	31
Delmarva Power and Light Company [Member] \| Surety Bonds
Other Commitments [Line Items]
Other Commitment	4
Other Commitment, to be Paid, Remainder of Fiscal Year	2
Other Commitment, to be Paid, Year One	2
Other Commitment, to be Paid, Year Two	0
Other Commitment, to be Paid, Year Three	0
Other Commitment, to be Paid, Year Four	0
Other Commitment, to be Paid, Year Five and Beyond	0
Delmarva Power and Light Company [Member] \| Guaranteed lease residual values
Other Commitments [Line Items]
Other Commitment	13
Other Commitment, to be Paid, Remainder of Fiscal Year	0
Other Commitment, to be Paid, Year One	1
Other Commitment, to be Paid, Year Two	1
Other Commitment, to be Paid, Year Three	3
Other Commitment, to be Paid, Year Four	3
Other Commitment, to be Paid, Year Five and Beyond	5
Atlantic City Electric Company [Member]
Other Commitments [Line Items]
Other Commitment	11
Other Commitment, to be Paid, Remainder of Fiscal Year	2
Other Commitment, to be Paid, Year One	3
Other Commitment, to be Paid, Year Two	1
Other Commitment, to be Paid, Year Three	1
Other Commitment, to be Paid, Year Four	1
Other Commitment, to be Paid, Year Five and Beyond	3
Guarantor Obligations, Maximum Exposure, Undiscounted	18
Atlantic City Electric Company [Member] \| Surety Bonds
Other Commitments [Line Items]
Other Commitment	4
Other Commitment, to be Paid, Remainder of Fiscal Year	2
Other Commitment, to be Paid, Year One	2
Other Commitment, to be Paid, Year Two	0
Other Commitment, to be Paid, Year Three	0
Other Commitment, to be Paid, Year Four	0
Other Commitment, to be Paid, Year Five and Beyond	0
Atlantic City Electric Company [Member] \| Guaranteed lease residual values
Other Commitments [Line Items]
Other Commitment	7
Other Commitment, to be Paid, Remainder of Fiscal Year	0
Other Commitment, to be Paid, Year One	1
Other Commitment, to be Paid, Year Two	1
Other Commitment, to be Paid, Year Three	1
Other Commitment, to be Paid, Year Four	1
Other Commitment, to be Paid, Year Five and Beyond	$ 3
Minimum [Member] \| Guaranteed lease residual values
Other Commitments [Line Items]
Lessor, Operating Lease, Term of Contract	1 year
Maximum [Member] \| Guaranteed lease residual values
Other Commitments [Line Items]
Lessor, Operating Lease, Term of Contract	8 years

Commitments and Contingencies_5

Commitments and Contingencies - Schedule of Accruals for Environmental Matters (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Site Contingency [Line Items]
Total environmental investigation and remediation reserve	$ 461	$ 483
Exelon Generation Co L L C [Member]
Site Contingency [Line Items]
Total environmental investigation and remediation reserve	117	121
Commonwealth Edison Co [Member]
Site Contingency [Line Items]
Total environmental investigation and remediation reserve	273	293
PECO Energy Co [Member]
Site Contingency [Line Items]
Total environmental investigation and remediation reserve	22	23
Baltimore Gas and Electric Company [Member]
Site Contingency [Line Items]
Total environmental investigation and remediation reserve	6	2
Pepco Holdings LLC [Member]
Site Contingency [Line Items]
Total environmental investigation and remediation reserve	43	44
Potomac Electric Power Company [Member]
Site Contingency [Line Items]
Total environmental investigation and remediation reserve	41	42
Delmarva Power and Light Company [Member]
Site Contingency [Line Items]
Total environmental investigation and remediation reserve	1	1
Atlantic City Electric Company [Member]
Site Contingency [Line Items]
Total environmental investigation and remediation reserve	1	1
Accrual For MGP Investigation And Remediation [Member]
Site Contingency [Line Items]
Total environmental investigation and remediation reserve	297	314
Accrual For MGP Investigation And Remediation [Member] \| Exelon Generation Co L L C [Member]
Site Contingency [Line Items]
Total environmental investigation and remediation reserve	0	0
Accrual For MGP Investigation And Remediation [Member] \| Commonwealth Edison Co [Member]
Site Contingency [Line Items]
Total environmental investigation and remediation reserve	272	293
Accrual For MGP Investigation And Remediation [Member] \| PECO Energy Co [Member]
Site Contingency [Line Items]
Total environmental investigation and remediation reserve	20	21
Accrual For MGP Investigation And Remediation [Member] \| Baltimore Gas and Electric Company [Member]
Site Contingency [Line Items]
Total environmental investigation and remediation reserve	5	0
Accrual For MGP Investigation And Remediation [Member] \| Pepco Holdings LLC [Member]
Site Contingency [Line Items]
Total environmental investigation and remediation reserve	0	0
Accrual For MGP Investigation And Remediation [Member] \| Potomac Electric Power Company [Member]
Site Contingency [Line Items]
Total environmental investigation and remediation reserve	0	0
Accrual For MGP Investigation And Remediation [Member] \| Delmarva Power and Light Company [Member]
Site Contingency [Line Items]
Total environmental investigation and remediation reserve	0	0
Accrual For MGP Investigation And Remediation [Member] \| Atlantic City Electric Company [Member]
Site Contingency [Line Items]
Total environmental investigation and remediation reserve	$ 0	$ 0

Changes in Accumulated Other _3

Changes in Accumulated Other Comprehensive Income - Schedule of Changes in AOCI (Details) - USD ($) $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2021	Jun. 30, 2020
Movement in Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	$ 34,313	$ 34,868	$ 34,616	$ 34,573	$ 34,868	$ 34,573
Other comprehensive income	57	54	41	21	111	62
Ending balance	34,500	34,313	34,871	34,616	34,500	34,871
Gains (Losses) on Cash Flow Hedges
Movement in Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	(5)	(5)	(3)	(2)	(5)	(2)
OCI before reclassifications	0		0		0	(1)
Amounts reclassified from AOCI	0		0		0	0
Other comprehensive income	0		0		0	(1)
Ending balance	(5)	(5)	(3)	(3)	(5)	(3)
Pension and Non-Pension Postretirement Benefit Plan Items
Movement in Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	(3,319)	(3,372)	(3,135)	(3,165)	(3,372)	(3,165)
OCI before reclassifications	0		2		(2)	(5)
Amounts reclassified from AOCI	55		37		110	74
Other comprehensive income	55		39		108	69
Ending balance	(3,264)	(3,319)	(3,096)	(3,135)	(3,264)	(3,096)
Foreign Currency Items
Movement in Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	(22)	(23)	(35)	(27)	(23)	(27)
OCI before reclassifications	2		2		3	(6)
Amounts reclassified from AOCI	0		0		0	0
Other comprehensive income	2		2		3	(6)
Ending balance	(20)	(22)	(33)	(35)	(20)	(33)
Total
Movement in Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	(3,346)	(3,400)	(3,173)	(3,194)	(3,400)	(3,194)
OCI before reclassifications	2		4		1	(12)
Amounts reclassified from AOCI	55		37		110	74
Other comprehensive income	57	54	41	21	111	62
Ending balance	$ (3,289)	$ (3,346)	$ (3,132)	$ (3,173)	$ (3,289)	$ (3,132)

Changes in Accumulated Other _4

Changes in Accumulated Other Comprehensive Income - Income Taxes Allocated to Other Comprehensive Income (Loss) Components (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Prior service costs
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), Tax	$ 1	$ 4	$ 2	$ 8
Actuarial losses
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), Tax	(19)	(17)	(38)	(34)
Pension and Non-Pension Postretirement Benefit Plan Items
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), Tax	$ (1)	$ 0	$ (1)	$ 3

Variable Interest Entities - Na

Variable Interest Entities - Narrative (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020	Apr. 01, 2014
Variable Interest Entity [Line Items]
Guarantor Obligations, Maximum Exposure, Undiscounted	$ 75
Distributed Energy Company [Member]
Variable Interest Entity [Line Items]
Equity Method Investment, Ownership Percentage	90.00%	90.00%
VIE Distributed Energy Company
Variable Interest Entity [Line Items]
Equity Method Investment, Ownership Percentage	90.00%	90.00%
CENG [Member]
Variable Interest Entity [Line Items]
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners	49.99%
CENG [Member]
Variable Interest Entity [Line Items]
Equity Method Investment, Ownership Percentage	50.01%	50.01%
CENG [Member] \| Payment Guarantee [Member]
Variable Interest Entity [Line Items]
Guarantor Obligations, Maximum Exposure, Undiscounted			$ 245
CENG [Member] \| Financial Guarantee [Member]
Variable Interest Entity [Line Items]
Guarantor Obligations, Maximum Exposure, Undiscounted			$ 165
EGRP [Member]
Variable Interest Entity [Line Items]
Equity Method Investment, Ownership Percentage	51.00%	51.00%
Antelope Valley [Member]
Variable Interest Entity [Line Items]
Equity Method Investment, Ownership Percentage	100.00%	100.00%
Distributed Energy Company [Member]
Variable Interest Entity [Line Items]
Equity Method Investment, Ownership Percentage	31.00%	31.00%
NER [Member]
Variable Interest Entity [Line Items]
Equity Method Investment, Ownership Percentage	100.00%	100.00%
Exelon Generation Co L L C [Member] \| Distributed Energy Company [Member]
Variable Interest Entity [Line Items]
Equity Method Investment, Ownership Percentage	90.00%	90.00%
Exelon Generation Co L L C [Member] \| VIE Distributed Energy Company
Variable Interest Entity [Line Items]
Equity Method Investment, Ownership Percentage	90.00%	90.00%
Exelon Generation Co L L C [Member] \| CENG [Member]
Variable Interest Entity [Line Items]
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners	49.99%
Exelon Generation Co L L C [Member] \| CENG [Member]
Variable Interest Entity [Line Items]
Equity Method Investment, Ownership Percentage	50.01%	50.01%
Guarantor Obligations, Current Carrying Value	$ 688
Exelon Generation Co L L C [Member] \| EGRP [Member]
Variable Interest Entity [Line Items]
Equity Method Investment, Ownership Percentage	51.00%	51.00%
Exelon Generation Co L L C [Member] \| EGRP [Member] \| Solar project entities [Member]
Variable Interest Entity [Line Items]
Equity Method Investment, Ownership Percentage	100.00%
Exelon Generation Co L L C [Member] \| EGRP [Member] \| Wind project entities [Member]
Variable Interest Entity [Line Items]
Equity Method Investment, Ownership Percentage	100.00%
Exelon Generation Co L L C [Member] \| Antelope Valley [Member]
Variable Interest Entity [Line Items]
Equity Method Investment, Ownership Percentage	100.00%	100.00%
Exelon Generation Co L L C [Member] \| Distributed Energy Company [Member]
Variable Interest Entity [Line Items]
Equity Method Investment, Ownership Percentage	31.00%	31.00%
Exelon Generation Co L L C [Member] \| NER [Member]
Variable Interest Entity [Line Items]
Equity Method Investment, Ownership Percentage	100.00%	100.00%

Variable Interest Entities - As

Variable Interest Entities - Assets and Liabilities of Consolidated VIES (Details) - USD ($) $ in Millions		Jun. 30, 2021	Dec. 31, 2020	Jun. 30, 2020	Dec. 31, 2019
Variable Interest Entity [Line Items]
Cash and cash equivalents		$ 1,578	$ 663	$ 2,129	$ 587
Restricted cash and cash equivalents		379	438	373	358
Accounts receivable, net
Customer		3,138	3,231
Unamortized energy contract assets		37	38
Inventory, net
Materials and supplies		1,443	1,425
Assets held for sale		11	958
Other current assets		1,780	1,609
Total current assets		12,348	12,562
Property, plant and equipment, net		82,120	82,584
NDT funds		15,400	14,464
Unamortized energy contract assets		278	294
Other Assets, Noncurrent		2,964	2,982
Total assets	[1]	129,396	129,317
Long-term debt due within one year		3,633	1,819
Accounts payable		3,547	3,562
Accrued expenses		1,719	2,078
Unamortized energy contract liabilities		95	100
Liabilities held for sale		2	375
Other		1,139	1,264
Total current liabilities		13,919	12,771
Long-term debt		35,077	35,093
Asset retirement obligations, noncurrent		12,502	12,300
Unamortized energy contract liabilities		192	238
Other		2,848	2,942
Total liabilities	[1]	94,896	94,449
Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Cash and cash equivalents		233	98
Restricted cash and cash equivalents		57	47
Accounts receivable, net
Customer		169	148
Other		44	36
Unamortized energy contract assets		22	22
Inventory, net
Materials and supplies		255	244
Assets held for sale		0	101
Other current assets		408	674
Total current assets		1,188	1,370
Property, plant and equipment, net		5,656	5,803
NDT funds		3,215	3,007
Unamortized energy contract assets		237	249
Other Assets, Noncurrent		35	52
Total noncurrent assets		9,143	9,111
Total assets		10,331	10,481
Long-term debt due within one year		84	94
Accounts payable		67	81
Accrued expenses		56	70
Unamortized energy contract liabilities		1	4
Liabilities held for sale		0	16
Other		1	5
Total current liabilities		209	270
Long-term debt		860	889
Asset retirement obligations, noncurrent		2,377	2,318
Other		133	129
Total noncurrent liabilities		3,370	3,336
Total liabilities		3,579	3,606
Unrestricted Assets [Member] \| Variable Interest Entity, Primary Beneficiary [Member]
Accounts receivable, net
Unamortized energy contract assets		22	22
Inventory, net
Assets held for sale		0	9
Unamortized energy contract assets		216	249
Other Assets		0	1
Recourse [Member] \| Variable Interest Entity, Primary Beneficiary [Member]
Inventory, net
Total liabilities		1	8
Exelon Generation Co L L C [Member]
Variable Interest Entity [Line Items]
Cash and cash equivalents		542	226	483	303
Restricted cash and cash equivalents		59	89	153	146
Accounts receivable, net
Customer		1,335	1,298
Unamortized energy contract assets		37	38
Inventory, net
Materials and supplies		986	978
Assets held for sale		11	958
Other current assets		1,353	1,357
Total current assets		6,209	6,947
Property, plant and equipment, net		19,837	22,214
NDT funds		15,400	14,464
Unamortized energy contract assets		278	293
Other Assets, Noncurrent		1,725	1,826
Total assets	[2]	45,821	48,094
Long-term debt due within one year		1,229	197
Accounts payable		1,489	1,253
Accrued expenses		654	788
Unamortized energy contract liabilities		4	7
Liabilities held for sale		2	375
Other		313	444
Total current liabilities		5,513	5,219
Long-term debt		4,627	5,566
Asset retirement obligations, noncurrent		12,257	12,054
Unamortized energy contract liabilities		3	3
Other		1,266	1,308
Total liabilities	[2]	32,836	33,418
Exelon Generation Co L L C [Member] \| Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Cash and cash equivalents		233	98
Restricted cash and cash equivalents		54	44
Accounts receivable, net
Customer		169	148
Other		44	36
Unamortized energy contract assets		22	22
Inventory, net
Materials and supplies		255	244
Assets held for sale		0	101
Other current assets		404	669
Total current assets		1,181	1,362
Property, plant and equipment, net		5,656	5,803
NDT funds		3,215	3,007
Unamortized energy contract assets		237	249
Other Assets, Noncurrent		26	42
Total noncurrent assets		9,134	9,101
Total assets		10,315	10,463
Long-term debt due within one year		69	68
Accounts payable		67	81
Accrued expenses		56	70
Unamortized energy contract liabilities		1	4
Liabilities held for sale		0	16
Other		1	5
Total current liabilities		194	244
Long-term debt		860	889
Asset retirement obligations, noncurrent		2,377	2,318
Other		133	129
Total noncurrent liabilities		3,370	3,336
Total liabilities		3,564	3,580
Exelon Generation Co L L C [Member] \| Unrestricted Assets [Member] \| Variable Interest Entity, Primary Beneficiary [Member]
Accounts receivable, net
Unamortized energy contract assets		22	22
Inventory, net
Assets held for sale		0	9
Unamortized energy contract assets		216	249
Other Assets		0	1
Exelon Generation Co L L C [Member] \| Recourse [Member] \| Variable Interest Entity, Primary Beneficiary [Member]
Inventory, net
Total liabilities		1	8
Pepco Holdings LLC [Member]
Variable Interest Entity [Line Items]
Cash and cash equivalents		61	111	39	131
Restricted cash and cash equivalents		42	39	36	36
Accounts receivable, net
Customer		524	525
Inventory, net
Materials and supplies		196	198
Other current assets		77	45
Total current assets		1,585	1,599
Property, plant and equipment, net		15,927	15,377
Other Assets, Noncurrent		295	307
Total assets	[3]	24,235	23,736
Long-term debt due within one year		300	347
Accounts payable		517	539
Accrued expenses		246	299
Unamortized energy contract liabilities		92	92
Other		131	141
Total current liabilities		1,914	2,154
Long-term debt		7,069	6,659
Asset retirement obligations, noncurrent		59	59
Unamortized energy contract liabilities		190	235
Other		590	622
Total liabilities	[3]	13,776	13,692
Pepco Holdings LLC [Member] \| Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Cash and cash equivalents		0	0
Restricted cash and cash equivalents		3	3
Accounts receivable, net
Customer		0	0
Other		0	0
Unamortized energy contract assets		0	0
Inventory, net
Materials and supplies		0	0
Assets held for sale		0	0
Other current assets		4	5
Total current assets		7	8
Property, plant and equipment, net		0	0
NDT funds		0	0
Unamortized energy contract assets		0	0
Other Assets, Noncurrent		9	10
Total noncurrent assets		9	10
Total assets		16	18
Long-term debt due within one year		15	26
Accounts payable		0	0
Accrued expenses		0	0
Unamortized energy contract liabilities		0	0
Liabilities held for sale		0	0
Other		0	0
Total current liabilities		15	26
Long-term debt		0	0
Asset retirement obligations, noncurrent		0	0
Other		0	0
Total noncurrent liabilities		0	0
Total liabilities		15	26
Atlantic City Electric Company [Member]
Variable Interest Entity [Line Items]
Cash and cash equivalents		11	17	8	12
Restricted cash and cash equivalents		3	3	$ 3	$ 2
Accounts receivable, net
Customer		152	124
Inventory, net
Other current assets		5	3
Total current assets		353	326
Property, plant and equipment, net		3,614	3,475
Other Assets, Noncurrent		49	50
Total assets	[4]	4,473	4,286
Long-term debt due within one year		13	261
Accounts payable		170	177
Accrued expenses		38	46
Other		11	11
Total current liabilities		499	780
Long-term debt		1,502	1,152
Other		47	48
Total liabilities	[4]	2,957	2,895
Atlantic City Electric Company [Member] \| Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Cash and cash equivalents		0	0
Restricted cash and cash equivalents		3	3
Accounts receivable, net
Customer		0	0
Other		0	0
Unamortized energy contract assets		0	0
Inventory, net
Materials and supplies		0	0
Assets held for sale		0	0
Other current assets		0	0
Total current assets		3	3
Property, plant and equipment, net		0	0
NDT funds		0	0
Unamortized energy contract assets		0	0
Other Assets, Noncurrent		9	10
Total noncurrent assets		9	10
Total assets		12
Long-term debt due within one year		11	21
Accounts payable		0	0
Accrued expenses		0	0
Unamortized energy contract liabilities		0	0
Liabilities held for sale		0	0
Other		0	0
Total current liabilities		11	21
Long-term debt		0	0
Asset retirement obligations, noncurrent		0	0
Other		0	0
Total noncurrent liabilities		0	0
Total liabilities		$ 11	$ 21

[1]	Exelon’s consolidated assets include $10,093 million and $10,200 million at June 30, 2021 and December 31, 2020, respectively, of certain VIEs that can only be used to settle the liabilities of the VIE. Exelon’s consolidated liabilities include $3,578 million and $3,598 million at June 30, 2021 and December 31, 2020, respectively, of certain VIEs for which the VIE creditors do not have recourse to Exelon. See Note 17 — Variable Interest Entities for additional information.
[2]	Generation’s consolidated assets include $10,077 million and $10,182 million at June 30, 2021 and December 31, 2020, respectively, of certain VIEs that can only be used to settle the liabilities of the VIE. Generation’s consolidated liabilities include $3,563 million and $3,572 million at June 30, 2021 and December 31, 2020, respectively, of certain VIEs for which the VIE creditors do not have recourse to Generation. See Note 17 — Variable Interest Entities for additional information.
[3]	PHI’s consolidated total assets include $16 million and $18 million at June 30, 2021 and December 31, 2020, respectively, of PHI's consolidated VIE that can only be used to settle the liabilities of the VIE. PHI’s consolidated total liabilities include $15 million and $26 million at June 30, 2021 and December 31, 2020, respectively, of PHI's consolidated VIE for which the VIE creditors do not have recourse to PHI. See Note 17 — Variable Interest Entities for additional information.
[4]	ACE’s consolidated total assets include $12 million and $13 million at June 30, 2021 and December 31, 2020, respectively, of ACE's consolidated VIE that can only be used to settle the liabilities of the VIE. ACE’s consolidated total liabilities include $11 million and $21 million at June 30, 2021 and December 31, 2020, respectively, of ACE's consolidated VIE for which the VIE creditors do not have recourse to ACE. See Note 17 — Variable Interest Entities for additional information.

Variable Interest Entities - Su

Variable Interest Entities - Summary of Significant Unconsolidated VIEs (Details) - USD ($) $ in Millions		Jun. 30, 2021	Dec. 31, 2020
Variable Interest Entity [Line Items]
Total assets	[1]	$ 129,396	$ 129,317
Total liabilities	[1]	94,896	94,449
Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Total assets		1,164	1,178
Total liabilities		305	284
Exelon's ownership interest in VIE		149	157
Other ownership interests in VIE		710	737
Exelon Generation Co L L C [Member]
Variable Interest Entity [Line Items]
Total assets	[2]	45,821	48,094
Total liabilities	[2]	32,836	33,418
Exelon Generation Co L L C [Member] \| Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Total assets		1,164	1,178
Total liabilities		305	284
Exelon's ownership interest in VIE		149	157
Other ownership interests in VIE		710	737
Commercial Agreement VIE [Member] \| Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Total assets		786	777
Total liabilities		95	61
Exelon's ownership interest in VIE		0	0
Other ownership interests in VIE		691	716
Commercial Agreement VIE [Member] \| Exelon Generation Co L L C [Member] \| Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Total assets		786	777
Total liabilities		95	61
Exelon's ownership interest in VIE		0	0
Other ownership interests in VIE		691	716
Equity Investment VIE [Member] \| Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Total assets		378	401
Total liabilities		210	223
Exelon's ownership interest in VIE		149	157
Other ownership interests in VIE		19	21
Equity Investment VIE [Member] \| Exelon Generation Co L L C [Member] \| Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Total assets		378	401
Total liabilities		210	223
Exelon's ownership interest in VIE		149	157
Other ownership interests in VIE		$ 19	$ 21

[1]	Exelon’s consolidated assets include $10,093 million and $10,200 million at June 30, 2021 and December 31, 2020, respectively, of certain VIEs that can only be used to settle the liabilities of the VIE. Exelon’s consolidated liabilities include $3,578 million and $3,598 million at June 30, 2021 and December 31, 2020, respectively, of certain VIEs for which the VIE creditors do not have recourse to Exelon. See Note 17 — Variable Interest Entities for additional information.
[2]	Generation’s consolidated assets include $10,077 million and $10,182 million at June 30, 2021 and December 31, 2020, respectively, of certain VIEs that can only be used to settle the liabilities of the VIE. Generation’s consolidated liabilities include $3,563 million and $3,572 million at June 30, 2021 and December 31, 2020, respectively, of certain VIEs for which the VIE creditors do not have recourse to Generation. See Note 17 — Variable Interest Entities for additional information.

Supplemental Financial Inform_3

Supplemental Financial Information - Operations (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Supplemental Statement of Operations Information [Line Items]
Operating lease income	$ 13	$ 14	$ 17	$ 18
Variable lease income	74	80	137	149
Decommissioning-Related Activities [Abstract]
Net realized income on NDT funds - Regulatory agreement units	144	30	435	77
Net realized income on NDT funds - Non-regulatory agreement units	87	23	290	104
Net unrealized gains on NDT funds - Regulatory agreement units	361	645	279	(287)
Net unrealized gains on NDT funds - Non-regulatory agreement units	193	452	126	(253)
Regulatory offset to NDT fund-related activities	(402)	(542)	(569)	167
Decommissioning-related activities	383	608	561	(192)
AFUDC - Equity	35	26	64	49
Non-service net periodic benefit cost	26	14	46	24
Unrealized Gain (Loss) on Investments	119		96
Exelon Generation Co L L C [Member]
Supplemental Statement of Operations Information [Line Items]
Operating lease income	12	12	15	15
Variable lease income	74	79	137	148
Decommissioning-Related Activities [Abstract]
Net realized income on NDT funds - Regulatory agreement units	144	30	435	77
Net realized income on NDT funds - Non-regulatory agreement units	87	23	290	104
Net unrealized gains on NDT funds - Regulatory agreement units	361	645	279	(287)
Net unrealized gains on NDT funds - Non-regulatory agreement units	193	452	126	(253)
Regulatory offset to NDT fund-related activities	(402)	(542)	(569)	167
Decommissioning-related activities	383	608	561	(192)
AFUDC - Equity	0	0	0	0
Non-service net periodic benefit cost	0	0	0	0
Unrealized Gain (Loss) on Investments	119		96
Commonwealth Edison Co [Member]
Decommissioning-Related Activities [Abstract]
Net realized income on NDT funds - Regulatory agreement units	0	0	0	0
Net realized income on NDT funds - Non-regulatory agreement units	0	0	0	0
Net unrealized gains on NDT funds - Regulatory agreement units	0	0	0	0
Net unrealized gains on NDT funds - Non-regulatory agreement units	0	0	0	0
Regulatory offset to NDT fund-related activities	0	0	0	0
Decommissioning-related activities	0	0	0	0
AFUDC - Equity	9	8	13	14
Non-service net periodic benefit cost	0	0	0	0
Unrealized Gain (Loss) on Investments	0		0
PECO Energy Co [Member]
Decommissioning-Related Activities [Abstract]
Net realized income on NDT funds - Regulatory agreement units	0	0	0	0
Net realized income on NDT funds - Non-regulatory agreement units	0	0	0	0
Net unrealized gains on NDT funds - Regulatory agreement units	0	0	0	0
Net unrealized gains on NDT funds - Non-regulatory agreement units	0	0	0	0
Regulatory offset to NDT fund-related activities	0	0	0	0
Decommissioning-related activities	0	0	0	0
AFUDC - Equity	6	4	12	7
Non-service net periodic benefit cost	0	0	0	0
Unrealized Gain (Loss) on Investments	0		0
Baltimore Gas and Electric Company [Member]
Decommissioning-Related Activities [Abstract]
Net realized income on NDT funds - Regulatory agreement units	0	0	0	0
Net realized income on NDT funds - Non-regulatory agreement units	0	0	0	0
Net unrealized gains on NDT funds - Regulatory agreement units	0	0	0	0
Net unrealized gains on NDT funds - Non-regulatory agreement units	0	0	0	0
Regulatory offset to NDT fund-related activities	0	0	0	0
Decommissioning-related activities	0	0	0	0
AFUDC - Equity	7	6	14	10
Non-service net periodic benefit cost	0	0	0	0
Unrealized Gain (Loss) on Investments	0		0
Pepco Holdings LLC [Member]
Supplemental Statement of Operations Information [Line Items]
Operating lease income	1	1	2	2
Variable lease income	0	1	0	1
Decommissioning-Related Activities [Abstract]
Net realized income on NDT funds - Regulatory agreement units	0	0	0	0
Net realized income on NDT funds - Non-regulatory agreement units	0	0	0	0
Net unrealized gains on NDT funds - Regulatory agreement units	0	0	0	0
Net unrealized gains on NDT funds - Non-regulatory agreement units	0	0	0	0
Regulatory offset to NDT fund-related activities	0	0	0	0
Decommissioning-related activities	0	0	0	0
AFUDC - Equity	12	8	25	17
Non-service net periodic benefit cost	0	0	0	0
Unrealized Gain (Loss) on Investments	0		0
Potomac Electric Power Company [Member]
Decommissioning-Related Activities [Abstract]
Net realized income on NDT funds - Regulatory agreement units	0	0	0	0
Net realized income on NDT funds - Non-regulatory agreement units	0	0	0	0
Net unrealized gains on NDT funds - Regulatory agreement units	0	0	0	0
Net unrealized gains on NDT funds - Non-regulatory agreement units	0	0	0	0
Regulatory offset to NDT fund-related activities	0	0	0	0
Decommissioning-related activities	0	0	0	0
AFUDC - Equity	10	6	20	13
Non-service net periodic benefit cost	0	0	0	0
Unrealized Gain (Loss) on Investments	0		0
Delmarva Power and Light Company [Member]
Supplemental Statement of Operations Information [Line Items]
Operating lease income	1	1	2	2
Variable lease income	0	1	0	1
Decommissioning-Related Activities [Abstract]
Net realized income on NDT funds - Regulatory agreement units	0	0	0	0
Net realized income on NDT funds - Non-regulatory agreement units	0	0	0	0
Net unrealized gains on NDT funds - Regulatory agreement units	0	0	0	0
Net unrealized gains on NDT funds - Non-regulatory agreement units	0	0	0	0
Regulatory offset to NDT fund-related activities	0	0	0	0
Decommissioning-related activities	0	0	0	0
AFUDC - Equity	1	1	3	2
Non-service net periodic benefit cost	0	0	0	0
Unrealized Gain (Loss) on Investments	0		0
Atlantic City Electric Company [Member]
Decommissioning-Related Activities [Abstract]
Net realized income on NDT funds - Regulatory agreement units	0	0	0	0
Net realized income on NDT funds - Non-regulatory agreement units	0	0	0	0
Net unrealized gains on NDT funds - Regulatory agreement units	0	0	0	0
Net unrealized gains on NDT funds - Non-regulatory agreement units	0	0	0	0
Regulatory offset to NDT fund-related activities	0	0	0	0
Decommissioning-related activities	0	0	0	0
AFUDC - Equity	1	1	2	2
Non-service net periodic benefit cost	0	$ 0	0	$ 0
Unrealized Gain (Loss) on Investments	$ 0		$ 0

Supplemental Financial Inform_4

Supplemental Financial Information - Taxes Other Than Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Supplemental Statement of Operations Information [Line Items]
Utility taxes	$ 206	$ 196	$ 423	$ 414
Property	153	149	307	297
Payroll	61	61	122	125
Exelon Generation Co L L C [Member]
Supplemental Statement of Operations Information [Line Items]
Utility taxes	22	23	46	49
Property	66	64	133	133
Payroll	30	28	58	60
Commonwealth Edison Co [Member]
Supplemental Statement of Operations Information [Line Items]
Utility taxes	61	55	121	114
Property	8	8	16	15
Payroll	6	7	13	14
PECO Energy Co [Member]
Supplemental Statement of Operations Information [Line Items]
Utility taxes	32	31	66	62
Property	4	4	9	8
Payroll	4	4	8	8
Baltimore Gas and Electric Company [Member]
Supplemental Statement of Operations Information [Line Items]
Utility taxes	20	18	45	44
Property	43	40	85	79
Payroll	5	4	9	9
Pepco Holdings LLC [Member]
Supplemental Statement of Operations Information [Line Items]
Utility taxes	71	69	145	145
Property	31	33	63	62
Payroll	7	7	14	15
Potomac Electric Power Company [Member]
Supplemental Statement of Operations Information [Line Items]
Utility taxes	65	64	132	133
Property	20	21	42	41
Payroll	1	2	3	4
Delmarva Power and Light Company [Member]
Supplemental Statement of Operations Information [Line Items]
Utility taxes	5	5	11	10
Property	10	11	19	20
Payroll	1	1	3	2
Atlantic City Electric Company [Member]
Supplemental Statement of Operations Information [Line Items]
Utility taxes	0	0	1	1
Property	1	1	1	1
Payroll	$ 1	$ 1	$ 2	$ 2

Supplemental Financial Inform_5

Supplemental Financial Information - Cash Flow (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Depreciation, Amortization and Accretion [Abstract]
Property, plant and equipment			$ 3,043	$ 1,715
Amortization of regulatory assets			291	277
Amortization of intangible assets, net			29	31
Amortization of energy contract assets and liabilities			13	12
Nuclear fuel			549	459
ARO accretion			255	247
Total depreciation, amortization and accretion			4,180	2,741
Other Non-Cash Operating Activities [Abstract]
Pension and non-pension postretirement benefit costs			196	203
Allowance for credit losses			100	92
Other decommissioning-related activity			(636)	(60)
Energy-related options			20	27
True-up adjustments to decoupling mechanisms and formula rates	$ 47	$ (122)	176	(55)
Long-term incentive plan			62	(10)
Amortization of operating ROU asset			83	112
Deferred payments for legal settlements				200
AFUDC - Equity	(35)	(26)	(64)	(49)
Other Non-Cash Activity
Other Non-Cash Operating Activities [Abstract]
True-up adjustments to decoupling mechanisms and formula rates			(176)	55
Return on borrowed funds
Other Non-Cash Operating Activities [Abstract]
AFUDC - Equity			(64)	(49)
Exelon Generation Co L L C [Member]
Depreciation, Amortization and Accretion [Abstract]
Property, plant and equipment			1,844	577
Amortization of regulatory assets			0	0
Amortization of intangible assets, net			25	27
Amortization of energy contract assets and liabilities			13	10
Nuclear fuel			549	459
ARO accretion			255	247
Total depreciation, amortization and accretion			2,686	1,320
Other Non-Cash Operating Activities [Abstract]
Pension and non-pension postretirement benefit costs			56	58
Allowance for credit losses			46	13
Other decommissioning-related activity			(636)	(60)
Energy-related options			20	27
Long-term incentive plan			0	0
Amortization of operating ROU asset			51	80
Deferred payments for legal settlements				0
AFUDC - Equity	0	0	0	0
Exelon Generation Co L L C [Member] \| Other Non-Cash Activity
Other Non-Cash Operating Activities [Abstract]
True-up adjustments to decoupling mechanisms and formula rates			0	0
Exelon Generation Co L L C [Member] \| Return on borrowed funds
Other Non-Cash Operating Activities [Abstract]
AFUDC - Equity			0	0
Commonwealth Edison Co [Member]
Depreciation, Amortization and Accretion [Abstract]
Property, plant and equipment			480	458
Amortization of regulatory assets			109	89
Amortization of intangible assets, net			0	0
Amortization of energy contract assets and liabilities			0	0
Nuclear fuel			0	0
ARO accretion			0	0
Total depreciation, amortization and accretion			589	547
Other Non-Cash Operating Activities [Abstract]
Pension and non-pension postretirement benefit costs			64	57
Allowance for credit losses			24	17
Other decommissioning-related activity			0	0
Energy-related options			0	0
True-up adjustments to decoupling mechanisms and formula rates	9	(25)	64	(13)
Long-term incentive plan			0	0
Amortization of operating ROU asset			1	1
Deferred payments for legal settlements				200
AFUDC - Equity	(9)	(8)	(13)	(14)
Commonwealth Edison Co [Member] \| Other Non-Cash Activity
Other Non-Cash Operating Activities [Abstract]
True-up adjustments to decoupling mechanisms and formula rates			(64)	13
Commonwealth Edison Co [Member] \| Return on borrowed funds
Other Non-Cash Operating Activities [Abstract]
AFUDC - Equity			(13)	(14)
PECO Energy Co [Member]
Depreciation, Amortization and Accretion [Abstract]
Property, plant and equipment			165	159
Amortization of regulatory assets			8	14
Amortization of intangible assets, net			0	0
Amortization of energy contract assets and liabilities			0	0
Nuclear fuel			0	0
ARO accretion			0	0
Total depreciation, amortization and accretion			173	173
Other Non-Cash Operating Activities [Abstract]
Pension and non-pension postretirement benefit costs			4	3
Allowance for credit losses			17	29
Other decommissioning-related activity			0	0
Energy-related options			0	0
True-up adjustments to decoupling mechanisms and formula rates	7	4	17	5
Long-term incentive plan			0	0
Amortization of operating ROU asset			0	0
Deferred payments for legal settlements				0
AFUDC - Equity	(6)	(4)	(12)	(7)
PECO Energy Co [Member] \| Other Non-Cash Activity
Other Non-Cash Operating Activities [Abstract]
True-up adjustments to decoupling mechanisms and formula rates			(17)	(5)
PECO Energy Co [Member] \| Return on borrowed funds
Other Non-Cash Operating Activities [Abstract]
AFUDC - Equity			(12)	(7)
Baltimore Gas and Electric Company [Member]
Depreciation, Amortization and Accretion [Abstract]
Property, plant and equipment			215	195
Amortization of regulatory assets			78	77
Amortization of intangible assets, net			0	0
Amortization of energy contract assets and liabilities			0	0
Nuclear fuel			0	0
ARO accretion			0	0
Total depreciation, amortization and accretion			293	272
Other Non-Cash Operating Activities [Abstract]
Pension and non-pension postretirement benefit costs			29	31
Allowance for credit losses			4	10
Other decommissioning-related activity			0	0
Energy-related options			0	0
True-up adjustments to decoupling mechanisms and formula rates	(10)	(37)	8	0
Long-term incentive plan			0	0
Amortization of operating ROU asset			15	15
Deferred payments for legal settlements				0
AFUDC - Equity	(7)	(6)	(14)	(10)
Baltimore Gas and Electric Company [Member] \| Other Non-Cash Activity
Other Non-Cash Operating Activities [Abstract]
True-up adjustments to decoupling mechanisms and formula rates			(8)	0
Baltimore Gas and Electric Company [Member] \| Return on borrowed funds
Other Non-Cash Operating Activities [Abstract]
AFUDC - Equity			(14)	(10)
Pepco Holdings LLC [Member]
Depreciation, Amortization and Accretion [Abstract]
Property, plant and equipment			309	289
Amortization of regulatory assets			95	96
Amortization of intangible assets, net			0	0
Amortization of energy contract assets and liabilities			0	0
Nuclear fuel			0	0
ARO accretion			0	0
Total depreciation, amortization and accretion			404	385
Other Non-Cash Operating Activities [Abstract]
Pension and non-pension postretirement benefit costs			24	35
Allowance for credit losses			9	22
Other decommissioning-related activity			0	0
Energy-related options			0	0
True-up adjustments to decoupling mechanisms and formula rates	41	(64)	88	(47)
Long-term incentive plan			0	0
Amortization of operating ROU asset			14	14
Deferred payments for legal settlements				0
AFUDC - Equity	(12)	(8)	(25)	(17)
Pepco Holdings LLC [Member] \| Other Non-Cash Activity
Other Non-Cash Operating Activities [Abstract]
True-up adjustments to decoupling mechanisms and formula rates			(88)	47
Pepco Holdings LLC [Member] \| Return on borrowed funds
Other Non-Cash Operating Activities [Abstract]
AFUDC - Equity			(25)	(17)
Potomac Electric Power Company [Member]
Depreciation, Amortization and Accretion [Abstract]
Property, plant and equipment			135	126
Amortization of regulatory assets			64	60
Amortization of intangible assets, net			0	0
Amortization of energy contract assets and liabilities			0	0
Nuclear fuel			0	0
ARO accretion			0	0
Total depreciation, amortization and accretion			199	186
Other Non-Cash Operating Activities [Abstract]
Pension and non-pension postretirement benefit costs			3	7
Allowance for credit losses			5	12
Other decommissioning-related activity			0	0
Energy-related options			0	0
True-up adjustments to decoupling mechanisms and formula rates	19	(13)	46	2
Long-term incentive plan			0	0
Amortization of operating ROU asset			3	3
Deferred payments for legal settlements				0
AFUDC - Equity	(10)	(6)	(20)	(13)
Potomac Electric Power Company [Member] \| Other Non-Cash Activity
Other Non-Cash Operating Activities [Abstract]
True-up adjustments to decoupling mechanisms and formula rates			(46)	(2)
Potomac Electric Power Company [Member] \| Return on borrowed funds
Other Non-Cash Operating Activities [Abstract]
AFUDC - Equity			(20)	(13)
Delmarva Power and Light Company [Member]
Depreciation, Amortization and Accretion [Abstract]
Property, plant and equipment			84	76
Amortization of regulatory assets			20	18
Amortization of intangible assets, net			0	0
Amortization of energy contract assets and liabilities			0	0
Nuclear fuel			0	0
ARO accretion			0	0
Total depreciation, amortization and accretion			104	94
Other Non-Cash Operating Activities [Abstract]
Pension and non-pension postretirement benefit costs			1	4
Allowance for credit losses			2	8
Other decommissioning-related activity			0	0
Energy-related options			0	0
True-up adjustments to decoupling mechanisms and formula rates	10	(25)	19	(24)
Long-term incentive plan			0	0
Amortization of operating ROU asset			5	4
Deferred payments for legal settlements				0
AFUDC - Equity	(1)	(1)	(3)	(2)
Delmarva Power and Light Company [Member] \| Other Non-Cash Activity
Other Non-Cash Operating Activities [Abstract]
True-up adjustments to decoupling mechanisms and formula rates			(19)	24
Delmarva Power and Light Company [Member] \| Return on borrowed funds
Other Non-Cash Operating Activities [Abstract]
AFUDC - Equity			(3)	(2)
Atlantic City Electric Company [Member]
Depreciation, Amortization and Accretion [Abstract]
Property, plant and equipment			76	69
Amortization of regulatory assets			11	17
Amortization of intangible assets, net			0	0
Amortization of energy contract assets and liabilities			0	0
Nuclear fuel			0	0
ARO accretion			0	0
Total depreciation, amortization and accretion			87	86
Other Non-Cash Operating Activities [Abstract]
Pension and non-pension postretirement benefit costs			5	7
Allowance for credit losses			2	2
Other decommissioning-related activity			0	0
Energy-related options			0	0
True-up adjustments to decoupling mechanisms and formula rates	12	(26)	23	(25)
Long-term incentive plan			0	0
Amortization of operating ROU asset			2	2
Deferred payments for legal settlements				0
AFUDC - Equity	$ (1)	$ (1)	(2)	(2)
Atlantic City Electric Company [Member] \| Other Non-Cash Activity
Other Non-Cash Operating Activities [Abstract]
True-up adjustments to decoupling mechanisms and formula rates			(23)	25
Atlantic City Electric Company [Member] \| Return on borrowed funds
Other Non-Cash Operating Activities [Abstract]
AFUDC - Equity			$ (2)	$ (2)

Supplemental Financial Inform_6

Supplemental Financial Information - Balance Sheet (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020	Jun. 30, 2020	Dec. 31, 2019
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract]
Cash and cash equivalents	$ 1,578	$ 663	$ 2,129	$ 587
Restricted cash	379	438	373	358
Restricted cash included in other long-term assets	52	53	178	177
Cash, restricted cash, and cash equivalents - Held for Sale		12
Total cash, restricted cash, and cash equivalents	2,009	1,166	2,680	1,122
Accrued Expenses [Abstract]
Compensation-related accruals	730	1,069
Taxes accrued	473	527
Interest accrued	339	331
Exelon Generation Co L L C [Member]
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract]
Cash and cash equivalents	542	226	483	303
Restricted cash	59	89	153	146
Restricted cash included in other long-term assets	0	0	0	0
Cash, restricted cash, and cash equivalents - Held for Sale		12
Total cash, restricted cash, and cash equivalents	601	327	636	449
Accrued Expenses [Abstract]
Compensation-related accruals	255	426
Taxes accrued	242	229
Interest accrued	43	44
Commonwealth Edison Co [Member]
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract]
Cash and cash equivalents	71	83	403	90
Restricted cash	240	279	155	150
Restricted cash included in other long-term assets	43	43	166	163
Cash, restricted cash, and cash equivalents - Held for Sale		0
Total cash, restricted cash, and cash equivalents	354	405	724	403
Accrued Expenses [Abstract]
Compensation-related accruals	136	170
Taxes accrued	77	94
Interest accrued	116	109
PECO Energy Co [Member]
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract]
Cash and cash equivalents	376	19	380	21
Restricted cash	8	7	7	6
Restricted cash included in other long-term assets	0	0	0	0
Cash, restricted cash, and cash equivalents - Held for Sale		0
Total cash, restricted cash, and cash equivalents	384	26	387	27
Accrued Expenses [Abstract]
Compensation-related accruals	51	73
Taxes accrued	31	16
Interest accrued	40	37
Baltimore Gas and Electric Company [Member]
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract]
Cash and cash equivalents	368	144	195	24
Restricted cash	3	1	1	1
Restricted cash included in other long-term assets	0	0	0	0
Cash, restricted cash, and cash equivalents - Held for Sale		0
Total cash, restricted cash, and cash equivalents	371	145	196	25
Accrued Expenses [Abstract]
Compensation-related accruals	55	84
Taxes accrued	35	73
Interest accrued	45	46
Pepco Holdings LLC [Member]
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract]
Cash and cash equivalents	61	111	39	131
Restricted cash	42	39	36	36
Restricted cash included in other long-term assets	9	10	11	14
Cash, restricted cash, and cash equivalents - Held for Sale		0
Total cash, restricted cash, and cash equivalents	112	160	86	181
Accrued Expenses [Abstract]
Compensation-related accruals	85	109
Taxes accrued	86	117
Interest accrued	51	51
Potomac Electric Power Company [Member]
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract]
Cash and cash equivalents	17	30	19	30
Restricted cash	33	35	33	33
Restricted cash included in other long-term assets	0	0	0	0
Cash, restricted cash, and cash equivalents - Held for Sale		0
Total cash, restricted cash, and cash equivalents	50	65	52	63
Accrued Expenses [Abstract]
Compensation-related accruals	28	36
Taxes accrued	58	90
Interest accrued	27	26
Delmarva Power and Light Company [Member]
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract]
Cash and cash equivalents	17	15	6	13
Restricted cash	5	0	0	0
Restricted cash included in other long-term assets	0	0	0	0
Cash, restricted cash, and cash equivalents - Held for Sale		0
Total cash, restricted cash, and cash equivalents	22	15	6	13
Accrued Expenses [Abstract]
Compensation-related accruals	16	18
Taxes accrued	9	18
Interest accrued	8	7
Atlantic City Electric Company [Member]
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract]
Cash and cash equivalents	11	17	8	12
Restricted cash	3	3	3	2
Restricted cash included in other long-term assets	9	10	11	14
Cash, restricted cash, and cash equivalents - Held for Sale		0
Total cash, restricted cash, and cash equivalents	23	30	$ 22	$ 28
Accrued Expenses [Abstract]
Compensation-related accruals	13	17
Taxes accrued	9	12
Interest accrued	$ 12	$ 12

Related Party Transactions - Op

Related Party Transactions - Operating Revenues and Purchased Power and Fuel (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Related Party Transaction [Line Items]
Revenue from Related Parties	$ 0	$ 1	$ 0	$ 2
Exelon Generation Co L L C [Member]
Related Party Transaction [Line Items]
Revenue from Related Parties	254	271	549	601
Exelon Generation Co L L C [Member] \| Commonwealth Edison Co Affiliate [Member]
Related Party Transaction [Line Items]
Revenue from Related Parties	75	80	153	170
Purchased power and/or fuel from affiliates	(3)	(4)	(10)	(11)
Exelon Generation Co L L C [Member] \| PECO Energy Co Affiliate [Member]
Related Party Transaction [Line Items]
Revenue from Related Parties	41	41	83	78
Exelon Generation Co L L C [Member] \| Baltimore Gas And Electric Company Affiliate [Member]
Related Party Transaction [Line Items]
Revenue from Related Parties	58	70	130	169
Exelon Generation Co L L C [Member] \| Pepco Holdings LLC Affiliate [Member]
Related Party Transaction [Line Items]
Revenue from Related Parties	77	78	176	182
Exelon Generation Co L L C [Member] \| Potomac Electric Power Co Affiliate [Member]
Related Party Transaction [Line Items]
Revenue from Related Parties	55	60	130	139
Exelon Generation Co L L C [Member] \| Delmarva Power and Light Co Affiliate [Member]
Related Party Transaction [Line Items]
Revenue from Related Parties	17	16	37	38
Exelon Generation Co L L C [Member] \| Atlantic City Electric Co Affiliate [Member]
Related Party Transaction [Line Items]
Revenue from Related Parties	5	2	9	5
Exelon Generation Co L L C [Member] \| Exelon Business Services Co Affiliate [Member]
Related Party Transaction [Line Items]
Revenue from Related Parties	3	2	7	2
Commonwealth Edison Co [Member]
Related Party Transaction [Line Items]
Revenue from Related Parties	5	11	11	16
Purchased power and/or fuel from affiliates	(79)	(84)	(163)	(181)
Commonwealth Edison Co [Member] \| Exelon Generation Co LLC Affiliate [Member]
Related Party Transaction [Line Items]
Purchased power and/or fuel from affiliates	$ (78)	$ (84)	$ (163)	$ (181)

Related Party Transactions - BS

Related Party Transactions - BSC and PHISCO Service Companies (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Exelon Business Services Co Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction Capitalized Costs Support Services	$ 124	$ 129	$ 282	$ 242
PHI Service Co Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction Capitalized Costs Support Services	17	16	36	30
Exelon Generation Co L L C [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Expenses from Transactions with Related Party	137	136	282	277
Exelon Generation Co L L C [Member] \| Exelon Business Services Co Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Expenses from Transactions with Related Party	135	133	280	273
Related Party Transaction Capitalized Costs Support Services	10	14	33	25
Commonwealth Edison Co [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Expenses from Transactions with Related Party	73	67	144	140
Commonwealth Edison Co [Member] \| Exelon Business Services Co Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Expenses from Transactions with Related Party	72	67	143	138
Related Party Transaction Capitalized Costs Support Services	45	41	102	83
PECO Energy Co [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Expenses from Transactions with Related Party	43	40	83	78
PECO Energy Co [Member] \| Exelon Business Services Co Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Expenses from Transactions with Related Party	40	36	80	73
Related Party Transaction Capitalized Costs Support Services	17	18	44	33
Baltimore Gas and Electric Company [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Expenses from Transactions with Related Party	46	41	91	83
Baltimore Gas and Electric Company [Member] \| Exelon Business Services Co Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Expenses from Transactions with Related Party	45	40	88	82
Related Party Transaction Capitalized Costs Support Services	20	30	43	58
Pepco Holdings LLC [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Expenses from Transactions with Related Party	39	36	79	74
Pepco Holdings LLC [Member] \| Exelon Business Services Co Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Expenses from Transactions with Related Party	37	35	76	72
Related Party Transaction Capitalized Costs Support Services	32	26	60	43
Pepco Holdings LLC [Member] \| PHI Service Co Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Expenses from Transactions with Related Party	0	0	0	0
Related Party Transaction Capitalized Costs Support Services	17	16	36	30
Potomac Electric Power Company [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Expenses from Transactions with Related Party	51	52	103	103
Potomac Electric Power Company [Member] \| Exelon Business Services Co Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Expenses from Transactions with Related Party	23	20	45	41
Related Party Transaction Capitalized Costs Support Services	13	9	25	15
Potomac Electric Power Company [Member] \| PHI Service Co Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Expenses from Transactions with Related Party	28	32	57	62
Related Party Transaction Capitalized Costs Support Services	7	7	15	13
Delmarva Power and Light Company [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Expenses from Transactions with Related Party	39	38	79	75
Delmarva Power and Light Company [Member] \| Exelon Business Services Co Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Expenses from Transactions with Related Party	15	13	29	26
Related Party Transaction Capitalized Costs Support Services	10	9	19	14
Delmarva Power and Light Company [Member] \| PHI Service Co Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Expenses from Transactions with Related Party	24	25	49	49
Related Party Transaction Capitalized Costs Support Services	5	5	11	9
Atlantic City Electric Company [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Expenses from Transactions with Related Party	34	34	68	66
Atlantic City Electric Company [Member] \| Exelon Business Services Co Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Expenses from Transactions with Related Party	12	11	24	21
Related Party Transaction Capitalized Costs Support Services	8	8	15	12
Atlantic City Electric Company [Member] \| PHI Service Co Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Expenses from Transactions with Related Party	21	23	43	44
Related Party Transaction Capitalized Costs Support Services	$ 5	$ 4	$ 10	$ 8

Related Party Transactions - Cu

Related Party Transactions - Current Receivables From/Payables To Affiliates (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	$ 439	$ 544
Accounts Payable, Related Parties, Current	5	5
Exelon Generation Co L L C [Member]
Related Party Transaction [Line Items]
Accounts Payable, Related Parties, Current	119	107
Accounts Receivable, Related Parties, Current	117	153
Exelon Generation Co L L C [Member] \| Commonwealth Edison Co Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	52	78
Due to Related Parties, Current	7	50
Exelon Generation Co L L C [Member] \| PECO Energy Co Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	22	17
Exelon Generation Co L L C [Member] \| Baltimore Gas And Electric Company Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	8	11
Exelon Generation Co L L C [Member] \| Pepco Holdings LLC Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	0	0
Exelon Generation Co L L C [Member] \| Potomac Electric Power Co Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	12	13
Exelon Generation Co L L C [Member] \| Delmarva Power and Light Co Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	3	3
Exelon Generation Co L L C [Member] \| Atlantic City Electric Co Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	12	6
Exelon Generation Co L L C [Member] \| Other Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	8	25
Commonwealth Edison Co [Member]
Related Party Transaction [Line Items]
Accounts Payable, Related Parties, Current	102	96
Accounts Receivable, Related Parties, Current	22	22
Commonwealth Edison Co [Member] \| Exelon Generation Co LLC Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	20	13
Accounts Payable, Related Parties, Current	45	28
Commonwealth Edison Co [Member] \| Affiliated Entity [Member]
Related Party Transaction [Line Items]
Accounts Payable, Related Parties, Current	109	146
Commonwealth Edison Co [Member] \| PECO Energy Co Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	0	1
Commonwealth Edison Co [Member] \| Baltimore Gas And Electric Company Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	0	0
Commonwealth Edison Co [Member] \| Pepco Holdings LLC Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	0	0
Commonwealth Edison Co [Member] \| Potomac Electric Power Co Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	0	2
Commonwealth Edison Co [Member] \| Delmarva Power and Light Co Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	0	1
Commonwealth Edison Co [Member] \| Atlantic City Electric Co Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	0	0
Commonwealth Edison Co [Member] \| Other Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	2	5
PECO Energy Co [Member]
Related Party Transaction [Line Items]
Accounts Payable, Related Parties, Current	50	50
Accounts Receivable, Related Parties, Current	0	2
PECO Energy Co [Member] \| Exelon Generation Co LLC Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	0	0
PECO Energy Co [Member] \| Commonwealth Edison Co Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	0	0
PECO Energy Co [Member] \| Baltimore Gas And Electric Company Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	0	0
PECO Energy Co [Member] \| Pepco Holdings LLC Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	0	0
PECO Energy Co [Member] \| Potomac Electric Power Co Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	0	0
PECO Energy Co [Member] \| Delmarva Power and Light Co Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	0	0
PECO Energy Co [Member] \| Atlantic City Electric Co Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	0	0
PECO Energy Co [Member] \| Other Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	0	2
Baltimore Gas and Electric Company [Member]
Related Party Transaction [Line Items]
Accounts Payable, Related Parties, Current	41	61
Accounts Receivable, Related Parties, Current	0	3
Baltimore Gas and Electric Company [Member] \| Exelon Generation Co LLC Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	0	0
Baltimore Gas and Electric Company [Member] \| Commonwealth Edison Co Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	0	0
Baltimore Gas and Electric Company [Member] \| PECO Energy Co Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	0	0
Baltimore Gas and Electric Company [Member] \| Pepco Holdings LLC Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	0	0
Baltimore Gas and Electric Company [Member] \| Potomac Electric Power Co Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	0	1
Baltimore Gas and Electric Company [Member] \| Delmarva Power and Light Co Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	0	0
Baltimore Gas and Electric Company [Member] \| Atlantic City Electric Co Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	0	0
Baltimore Gas and Electric Company [Member] \| Other Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	0	2
Pepco Holdings LLC [Member]
Related Party Transaction [Line Items]
Accounts Payable, Related Parties, Current	75	104
Accounts Receivable, Related Parties, Current	1	8
Pepco Holdings LLC [Member] \| Affiliated Entity [Member]
Related Party Transaction [Line Items]
Accounts Payable, Related Parties, Current	14	15
Potomac Electric Power Company [Member]
Related Party Transaction [Line Items]
Accounts Payable, Related Parties, Current	42	55
Accounts Receivable, Related Parties, Current	0	2
Potomac Electric Power Company [Member] \| Exelon Generation Co LLC Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	0	0
Potomac Electric Power Company [Member] \| Commonwealth Edison Co Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	0	0
Potomac Electric Power Company [Member] \| PECO Energy Co Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	0	0
Potomac Electric Power Company [Member] \| Baltimore Gas And Electric Company Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	0	0
Potomac Electric Power Company [Member] \| Pepco Holdings LLC Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	0	0
Potomac Electric Power Company [Member] \| Delmarva Power and Light Co Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	0	0
Potomac Electric Power Company [Member] \| Atlantic City Electric Co Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	0	0
Potomac Electric Power Company [Member] \| Other Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	0	2
Delmarva Power and Light Company [Member]
Related Party Transaction [Line Items]
Accounts Payable, Related Parties, Current	23	36
Accounts Receivable, Related Parties, Current	0	1
Delmarva Power and Light Company [Member] \| Exelon Generation Co LLC Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	0	0
Delmarva Power and Light Company [Member] \| Commonwealth Edison Co Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	0	0
Delmarva Power and Light Company [Member] \| PECO Energy Co Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	0	0
Delmarva Power and Light Company [Member] \| Baltimore Gas And Electric Company Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	0	0
Delmarva Power and Light Company [Member] \| Pepco Holdings LLC Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	0	0
Delmarva Power and Light Company [Member] \| Potomac Electric Power Co Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	0	0
Delmarva Power and Light Company [Member] \| Atlantic City Electric Co Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	0	0
Delmarva Power and Light Company [Member] \| Other Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	0	1
Atlantic City Electric Company [Member]
Related Party Transaction [Line Items]
Accounts Payable, Related Parties, Current	30	31
Accounts Receivable, Related Parties, Current	1	6
Atlantic City Electric Company [Member] \| Exelon Generation Co LLC Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	0	0
Atlantic City Electric Company [Member] \| Commonwealth Edison Co Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	0	0
Atlantic City Electric Company [Member] \| PECO Energy Co Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	0	0
Atlantic City Electric Company [Member] \| Baltimore Gas And Electric Company Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	0	0
Atlantic City Electric Company [Member] \| Pepco Holdings LLC Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	0	0
Atlantic City Electric Company [Member] \| Potomac Electric Power Co Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	0	0
Atlantic City Electric Company [Member] \| Delmarva Power and Light Co Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	0	0
Atlantic City Electric Company [Member] \| Other Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	1	6
Business Services Company [Member]
Related Party Transaction [Line Items]
Accounts Receivable, Related Parties, Current	224	271
Business Services Company [Member] \| Exelon Generation Co LLC Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	84	72
Business Services Company [Member] \| Commonwealth Edison Co Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	50	59
Business Services Company [Member] \| PECO Energy Co Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	24	28
Business Services Company [Member] \| Baltimore Gas And Electric Company Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	31	47
Business Services Company [Member] \| Pepco Holdings LLC Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	4	4
Business Services Company [Member] \| Potomac Electric Power Co Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	14	25
Business Services Company [Member] \| Delmarva Power and Light Co Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	9	21
Business Services Company [Member] \| Atlantic City Electric Co Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	8	15
Business Services Company [Member] \| Other Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	0	0
PHI Service Company [Member]
Related Party Transaction [Line Items]
Accounts Receivable, Related Parties, Current	34	33
PHI Service Company [Member] \| Exelon Generation Co LLC Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	0	0
PHI Service Company [Member] \| Commonwealth Edison Co Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	0	0
PHI Service Company [Member] \| PECO Energy Co Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	0	0
PHI Service Company [Member] \| Baltimore Gas And Electric Company Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	0	0
PHI Service Company [Member] \| Pepco Holdings LLC Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	0	0
PHI Service Company [Member] \| Potomac Electric Power Co Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	14	14
PHI Service Company [Member] \| Delmarva Power and Light Co Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	10	10
PHI Service Company [Member] \| Atlantic City Electric Co Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	10	9
PHI Service Company [Member] \| Other Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	0	0
Other Legal Entities [Member]
Related Party Transaction [Line Items]
Accounts Payable, Related Parties, Current	11	43
Accounts Receivable, Related Parties, Current	41	51
Other Legal Entities [Member] \| Exelon Generation Co LLC Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	15	22
Other Legal Entities [Member] \| Commonwealth Edison Co Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	7	9
Other Legal Entities [Member] \| PECO Energy Co Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	4	4
Other Legal Entities [Member] \| Baltimore Gas And Electric Company Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	2	3
Other Legal Entities [Member] \| Pepco Holdings LLC Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	10	11
Other Legal Entities [Member] \| Potomac Electric Power Co Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	2	0
Other Legal Entities [Member] \| Delmarva Power and Light Co Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	1	1
Other Legal Entities [Member] \| Atlantic City Electric Co Affiliate [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	$ 0	$ 1

Related Party Transactions - No

Related Party Transactions - Noncurrent Receivables from/Payables to affiliates (Details) - Exelon Generation Co L L C [Member] - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Related Party Transaction [Line Items]
Accounts Payable, Related Parties, Noncurrent	$ 3,011	$ 3,017
Commonwealth Edison Co Affiliate [Member]
Related Party Transaction [Line Items]
Accounts Payable, Related Parties, Noncurrent	2,439	2,541
PECO Energy Co Affiliate [Member]
Related Party Transaction [Line Items]
Accounts Payable, Related Parties, Noncurrent	$ 571	$ 475

Related Party Transactions - Lo

Related Party Transactions - Long Term Debt to Financing Trusts (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Related Party Transaction [Line Items]
Long-term debt to financing trust	$ 390	$ 390
ComEd Financing Three Affiliate [Member]
Related Party Transaction [Line Items]
Long-term debt to financing trust	206	206
PECO Trust Three Affiliate [Member]
Related Party Transaction [Line Items]
Long-term debt to financing trust	81	81
PECO Trust Four Affiliate [Member]
Related Party Transaction [Line Items]
Long-term debt to financing trust	103	103
Commonwealth Edison Co [Member]
Related Party Transaction [Line Items]
Long-term debt to financing trust	205	205
Commonwealth Edison Co [Member] \| ComEd Financing Three Affiliate [Member]
Related Party Transaction [Line Items]
Long-term debt to financing trust	205	205
Commonwealth Edison Co [Member] \| PECO Trust Three Affiliate [Member]
Related Party Transaction [Line Items]
Long-term debt to financing trust	0	0
Commonwealth Edison Co [Member] \| PECO Trust Four Affiliate [Member]
Related Party Transaction [Line Items]
Long-term debt to financing trust	0	0
PECO Energy Co [Member]
Related Party Transaction [Line Items]
Long-term debt to financing trust	184	184
PECO Energy Co [Member] \| ComEd Financing Three Affiliate [Member]
Related Party Transaction [Line Items]
Long-term debt to financing trust	0	0
PECO Energy Co [Member] \| PECO Trust Three Affiliate [Member]
Related Party Transaction [Line Items]
Long-term debt to financing trust	81	81
PECO Energy Co [Member] \| PECO Trust Four Affiliate [Member]
Related Party Transaction [Line Items]
Long-term debt to financing trust	$ 103	$ 103