Southwest Gas (SWX) 10-Q8 May 242024 Q1 Quarterly reportFinancial data

Company Profile

Cover

Cover - shares	3 Months Ended
Cover - shares	Mar. 31, 2024	Apr. 26, 2024
Entity Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2024
Document Transition Report	false
Entity File Number	001-37976
Entity Registrant Name	Southwest Gas Holdings, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	81-3881866
Entity Address, Address Line One	8360 S. Durango Drive
Entity Address, Address Line Two	Post Office Box 98510
Entity Address, City or Town	Las Vegas,
Entity Address, State or Province	NV
Entity Address, Postal Zip Code	89193-8510
City Area Code	(702)
Local Phone Number	876-7237
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		71,669,140
Entity Central Index Key	0001692115
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q1
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Southwest Gas Holdings, Inc. Common Stock, $1 Par Value
Entity Information [Line Items]
Title of 12(b) Security	Southwest Gas Holdings, Inc. Common Stock, $1 Par Value
Trading Symbol	SWX
Security Exchange Name	NYSE
Preferred Stock Purchase Rights
Entity Information [Line Items]
Title of 12(b) Security	Preferred Stock Purchase Rights
Security Exchange Name	NYSE
No Trading Symbol - Preferred Stock Purchase Rights	true
Southwest Gas Corporation
Entity Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2024
Document Transition Report	false
Entity File Number	1-7850
Entity Registrant Name	Southwest Gas Corporation
Entity Incorporation, State or Country Code	CA
Entity Tax Identification Number	88-0085720
Entity Address, Address Line One	8360 S. Durango Drive
Entity Address, Address Line Two	Post Office Box 98510
Entity Address, City or Town	Las Vegas,
Entity Address, State or Province	NV
Entity Address, Postal Zip Code	89193-8510
City Area Code	(702)
Local Phone Number	876-7237
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Central Index Key	0000092416
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q1
Amendment Flag	false
Current Fiscal Year End Date	--12-31

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Regulated operations plant:
Gas plant	$ 10,253,377	$ 10,140,362
Less: accumulated depreciation	(2,863,941)	(2,822,669)
Construction work in progress	245,032	200,549
Net regulated operations plant	7,634,468	7,518,242
Other property and investments, net	1,252,861	1,266,340
Current assets:
Cash and cash equivalents	457,952	106,536
Accounts receivable, net of allowance	843,133	886,549
Accrued utility revenue	58,500	93,000
Income taxes receivable, net	7,174	1,935
Deferred purchased gas costs	198,682	552,885
Prepaid and other current assets	214,516	218,832
Current assets held for sale	0	21,377
Total current assets	1,779,957	1,881,114
Noncurrent assets:
Goodwill	787,206	789,729
Deferred income taxes	1,309	463
Deferred charges and other assets	432,193	414,008
Total noncurrent assets	1,220,708	1,204,200
Total assets	11,887,994	11,869,896
Capitalization:
Common stock, $1 par (authorized - 120,000,000 shares; issued and outstanding - 71,665,592 and 71,563,750 shares)	73,295	73,194
Additional paid-in capital	2,547,485	2,541,790
Accumulated other comprehensive loss, net	(46,222)	(43,787)
Retained earnings	781,683	738,839
Total equity	3,356,241	3,310,036
Redeemable noncontrolling interests	7,661	104,667
Long-term debt, less current maturities	4,648,958	4,609,838
Total capitalization	8,012,860	8,024,541
Current liabilities:
Current maturities of long-term debt	42,770	42,552
Short-term debt	644,000	628,500
Accounts payable	264,620	346,907
Customer deposits	52,632	48,460
Income taxes payable, net	744	817
Accrued general taxes	96,676	58,053
Accrued interest	39,985	36,605
Other current liabilities	577,237	522,953
Total current liabilities	1,718,664	1,684,847
Deferred income taxes and other credits:
Deferred income taxes and investment tax credits, net	784,491	752,997
Accumulated removal costs	457,000	458,000
Other deferred credits and other long-term liabilities	914,979	949,511
Total deferred income taxes and other credits	2,156,470	2,160,508
Total capitalization and liabilities	$ 11,887,994	$ 11,869,896

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Mar. 31, 2024	Dec. 31, 2023
Statement of Financial Position [Abstract]
Common stock, par (in USD per share)	$ 1	$ 1
Common stock, authorized (in shares)	120,000,000	120,000,000
Common stock, issued (in shares)	71,665,592	71,563,750
Common stock, outstanding (in shares)	71,665,592	71,563,750

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF INCOME - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Operating revenues:
Regulated operations revenues	$ 1,052,933	$ 950,011
Utility infrastructure services revenues	528,023	653,293
Total operating revenues	1,580,956	1,603,304
Operating expenses:
Net cost of gas sold	629,997	507,537
Operations and maintenance	135,146	148,908
Depreciation and amortization	119,142	112,520
Taxes other than income taxes	22,903	24,230
Utility infrastructure services expenses	515,643	603,680
Goodwill impairment and loss on sale	0	71,230
Total operating expenses	1,422,831	1,468,105
Operating income	158,125	135,199
Other income and (expenses):
Net interest deductions	(71,605)	(77,334)
Other income	18,121	18,460
Total other (expenses)	(53,484)	(58,874)
Income before income taxes	104,641	76,325
Income tax expense	17,079	28,675
Net income	87,562	47,650
Net income (loss) attributable to noncontrolling interests	(175)	1,739
Net income attributable to Southwest Gas Holdings, Inc.	$ 87,737	$ 45,911
Earnings per share:
Basic (in USD per share)	$ 1.22	$ 0.67
Diluted (in USD per share)	$ 1.22	$ 0.67
Weighted average shares:
Basic (in shares)	71,728	68,265
Diluted (in shares)	71,882	68,419

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Statement of Comprehensive Income [Abstract]
Net income	$ 87,562	$ 47,650
Defined benefit pension plans:
Amortization of prior service cost	33	33
Amortization of net actuarial loss	1,451	253
Regulatory adjustment	(1,100)	(90)
Net defined benefit pension plans	384	196
Foreign currency translation adjustments	(2,819)	97
Total other comprehensive income (loss), net of tax	(2,435)	293
Comprehensive income	85,127	47,943
Comprehensive income (loss) attributable to noncontrolling interests	(175)	1,739
Comprehensive income attributable to Southwest Gas Holdings, Inc.	$ 85,302	$ 46,204

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
CASH FLOW FROM OPERATING ACTIVITIES:
Net income	$ 87,562	$ 47,650
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation and amortization	119,142	112,520
Impairment of assets and other charges	0	71,230
Deferred income taxes	30,707	36,712
Gains on sale of property and equipment	(944)	(661)
Changes in undistributed stock compensation	961	3,436
Equity AFUDC	(1,839)	(82)
Changes in current assets and liabilities:
Accounts receivable, net of allowances	26,110	(40,185)
Accrued utility revenue	34,500	31,200
Deferred purchased gas costs	354,203	(535,224)
Accounts payable	(69,863)	(305,272)
Accrued taxes	33,311	34,950
Other current assets and liabilities	(28,763)	371,035
Changes in deferred charges and other assets	(15,982)	(1,565)
Changes in other liabilities and deferred credits	(25,396)	(11,486)
Net cash provided by (used in) operating activities	543,709	(185,742)
CASH FLOW FROM INVESTING ACTIVITIES:
Construction expenditures and property additions	(221,198)	(219,124)
Proceeds from the sale of business, net of cash sold	0	1,058,272
Proceeds from the sale of property	21,377	0
Changes in customer advances	(1,658)	(6,608)
Other	1,689	3,125
Net cash provided by (used in) investing activities	(199,790)	835,665
CASH FLOW FROM FINANCING ACTIVITIES:
Issuance of common stock, net	2,372	239,337
Centuri distribution to redeemable noncontrolling interest	(37)	0
Dividends paid	(44,389)	(41,631)
Issuance of long-term debt, net	55,897	305,896
Retirement of long-term debt	(16,488)	(84,224)
Change in short-term portion of credit facility	15,500	(155,000)
Change in long-term credit facility and commercial paper	0	(50,000)
Issuance of short-term debt	0	450,000
Repayment of short-term debt	0	(1,372,746)
Withholding remittance - share-based compensation	(1,971)	(1,506)
Other, including principal payments on finance leases	(3,190)	(4,949)
Net cash provided by (used in) financing activities	7,694	(714,823)
Effects of currency translation on cash and cash equivalents	(197)	104
Change in cash and cash equivalents	351,416	(64,796)
Cash and cash equivalents at beginning of period	106,536	123,078
Cash and cash equivalents at end of period	457,952	82,085
SUPPLEMENTAL INFORMATION:
Interest paid, net of amounts capitalized	65,281	68,018
Income taxes paid, net	$ 1,833	$ 2,381

CONDENSED CONSOLIDATED STATEM_4

CONDENSED CONSOLIDATED STATEMENTS OF EQUITY - USD ($) $ in Thousands	Total	Common stock shares	Additional paid-in capital	Accumulated other comprehensive loss	Retained earnings	Southwest Gas Holdings, Inc.
Beginning balance (in shares) at Dec. 31, 2022		67,119,000
Beginning balance at Dec. 31, 2022		$ 68,749	$ 2,287,183	$ (44,242)	$ 747,069
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock issuances (in shares)		4,212,000
Common stock issuances		$ 4,212	237,448
Promissory notes in association with redeemable noncontrolling interest			0
Foreign currency exchange translation adjustment				97
Net actuarial gain arising during period, less amortization of unamortized benefit plan cost, net of tax				196
Net income					45,911
Dividends declared					(44,635)
Redemption value adjustments					(5,832)
Ending balance (in shares) at Mar. 31, 2023		71,331,000
Ending balance at Mar. 31, 2023		$ 72,961	2,524,631	(43,949)	742,513	$ 3,296,156
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends declared per common share (in USD per share)	$ 0.62
Beginning balance (in shares) at Dec. 31, 2023	71,563,750	71,564,000
Beginning balance at Dec. 31, 2023		$ 73,194	2,541,790	(43,787)	738,839
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock issuances (in shares)		101,000
Common stock issuances		$ 101	1,508
Promissory notes in association with redeemable noncontrolling interest			4,187
Foreign currency exchange translation adjustment				(2,819)
Net actuarial gain arising during period, less amortization of unamortized benefit plan cost, net of tax				384
Net income					87,737
Dividends declared					(44,699)
Redemption value adjustments	$ 194				(194)
Ending balance (in shares) at Mar. 31, 2024	71,665,592	71,665,000
Ending balance at Mar. 31, 2024		$ 73,295	$ 2,547,485	$ (46,222)	$ 781,683	$ 3,356,241
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends declared per common share (in USD per share)	$ 0.62

CONDENSED CONSOLIDATED BALANC_3

CONDENSED CONSOLIDATED BALANCE SHEETS - Southwest - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Regulated operations plant:
Gas plant	$ 10,253,377	$ 10,140,362
Less: accumulated depreciation	(2,863,941)	(2,822,669)
Construction work in progress	245,032	200,549
Net regulated operations plant	7,634,468	7,518,242
Other property and investments, net	1,252,861	1,266,340
Current assets:
Cash and cash equivalents	457,952	106,536
Accounts receivable, net of allowance	843,133	886,549
Accrued utility revenue	58,500	93,000
Income taxes receivable, net	7,174	1,935
Deferred purchased gas costs	198,682	552,885
Prepaid and other current assets	214,516	218,832
Current assets held for sale	0	21,377
Total current assets	1,779,957	1,881,114
Noncurrent assets:
Goodwill	787,206	789,729
Deferred charges and other assets	432,193	414,008
Total noncurrent assets	1,220,708	1,204,200
Total assets	11,887,994	11,869,896
Capitalization:
Common stock	73,295	73,194
Additional paid-in capital	2,547,485	2,541,790
Accumulated other comprehensive loss, net	(46,222)	(43,787)
Retained earnings	781,683	738,839
Total equity	3,356,241	3,310,036
Long-term debt, less current maturities	4,648,958	4,609,838
Total capitalization	8,012,860	8,024,541
Current liabilities:
Accounts payable	264,620	346,907
Customer deposits	52,632	48,460
Accrued general taxes	96,676	58,053
Accrued interest	39,985	36,605
Other current liabilities	577,237	522,953
Total current liabilities	1,718,664	1,684,847
Deferred income taxes and other credits:
Deferred income taxes and investment tax credits, net	784,491	752,997
Accumulated removal costs	457,000	458,000
Other deferred credits and other long-term liabilities	914,979	949,511
Total deferred income taxes and other credits	2,156,470	2,160,508
Total capitalization and liabilities	11,887,994	11,869,896
Southwest Gas Corporation
Regulated operations plant:
Gas plant	10,253,377	10,140,362
Less: accumulated depreciation	(2,863,941)	(2,822,669)
Construction work in progress	245,032	200,549
Net regulated operations plant	7,634,468	7,518,242
Other property and investments, net	156,262	152,658
Current assets:
Cash and cash equivalents	436,403	71,154
Accounts receivable, net of allowance	297,488	269,195
Accrued utility revenue	58,500	93,000
Income taxes receivable, net	28	26
Deferred purchased gas costs	198,682	552,885
Prepaid and other current assets	187,146	188,138
Current assets held for sale	0	21,376
Total current assets	1,178,247	1,195,774
Noncurrent assets:
Goodwill	11,155	11,155
Deferred charges and other assets	390,333	390,742
Total noncurrent assets	401,488	401,897
Total assets	9,370,465	9,268,571
Capitalization:
Common stock	49,112	49,112
Additional paid-in capital	2,156,318	2,156,577
Accumulated other comprehensive loss, net	(40,164)	(40,548)
Retained earnings	1,112,273	1,018,474
Total equity	3,277,539	3,183,615
Long-term debt, less current maturities	3,502,411	3,501,543
Total capitalization	6,779,950	6,685,158
Current liabilities:
Customer deposits	52,631	48,460
Accrued general taxes	96,676	58,053
Accrued interest	38,340	34,955
Other current liabilities	300,865	271,899
Total current liabilities	627,719	630,822
Deferred income taxes and other credits:
Deferred income taxes and investment tax credits, net	790,312	749,836
Accumulated removal costs	457,000	458,000
Other deferred credits and other long-term liabilities	715,484	744,755
Total deferred income taxes and other credits	1,962,796	1,952,591
Total capitalization and liabilities	9,370,465	9,268,571
Southwest Gas Corporation \| Nonrelated Party
Current liabilities:
Accounts payable	138,938	215,744
Southwest Gas Corporation \| Related Party
Current liabilities:
Accounts payable	$ 269	$ 1,711

CONDENSED CONSOLIDATED STATEM_5

CONDENSED CONSOLIDATED STATEMENTS OF INCOME - Southwest - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Regulated operations revenues	$ 1,580,956	$ 1,603,304
Operating expenses:
Net cost of gas sold	629,997	507,537
Operations and maintenance	135,146	148,908
Depreciation and amortization	119,142	112,520
Taxes other than income taxes	22,903	24,230
Total operating expenses	1,422,831	1,468,105
Operating income	158,125	135,199
Other income and (expenses):
Net interest deductions	(71,605)	(77,334)
Other income	18,121	18,460
Total other (expenses)	(53,484)	(58,874)
Income before income taxes	104,641	76,325
Income tax expense	17,079	28,675
Net income attributable to Southwest Gas Holdings, Inc.	87,737	45,911
Southwest Gas Corporation
Regulated operations revenues	1,052,933	914,879
Operating expenses:
Net cost of gas sold	629,997	501,169
Operations and maintenance	130,866	131,188
Depreciation and amortization	84,823	74,650
Taxes other than income taxes	22,903	22,740
Total operating expenses	868,589	729,747
Operating income	184,344	185,132
Other income and (expenses):
Net interest deductions	(36,444)	(38,622)
Other income	18,100	18,443
Total other (expenses)	(18,344)	(20,179)
Income before income taxes	166,000	164,953
Income tax expense	30,175	30,257
Net income attributable to Southwest Gas Holdings, Inc.	$ 135,825	$ 134,696

CONDENSED CONSOLIDATED STATEM_6

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - Southwest - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Net income	$ 87,562	$ 47,650
Defined benefit pension plans:
Amortization of prior service cost	33	33
Amortization of net actuarial loss	1,451	253
Regulatory adjustment	(1,100)	(90)
Net defined benefit pension plans	384	196
Total other comprehensive income (loss), net of tax	(2,435)	293
Comprehensive income	85,127	47,943
Southwest Gas Corporation
Net income	135,825	134,696
Defined benefit pension plans:
Amortization of prior service cost	33	33
Amortization of net actuarial loss	1,451	253
Regulatory adjustment	(1,100)	(90)
Net defined benefit pension plans	384	196
Total other comprehensive income (loss), net of tax	384	196
Comprehensive income	$ 136,209	$ 134,892

CONDENSED CONSOLIDATED STATEM_7

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - Southwest - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
CASH FLOW FROM OPERATING ACTIVITIES:
Net income	$ 87,562	$ 47,650
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation and amortization	119,142	112,520
Deferred income taxes	30,707	36,712
Changes in undistributed stock compensation	961	3,436
Equity AFUDC	(1,839)	(82)
Changes in current assets and liabilities:
Accounts receivable, net of allowance	26,110	(40,185)
Accrued utility revenue	34,500	31,200
Deferred purchased gas costs	354,203	(535,224)
Accounts payable	(69,863)	(305,272)
Accrued taxes	33,311	34,950
Other current assets and liabilities	(28,763)	371,035
Changes in deferred charges and other assets	(15,982)	(1,565)
Changes in other liabilities and deferred credits	(25,396)	(11,486)
Net cash provided by (used in) operating activities	543,709	(185,742)
CASH FLOW FROM INVESTING ACTIVITIES:
Construction expenditures and property additions	(221,198)	(219,124)
Proceeds from the sale of property	21,377	0
Changes in customer advances	(1,658)	(6,608)
Other	1,689	3,125
Net cash provided by (used in) investing activities	(199,790)	835,665
CASH FLOW FROM FINANCING ACTIVITIES:
Dividends paid	(44,389)	(41,631)
Issuance of long-term debt, net	55,897	305,896
Change in long-term credit facility and commercial paper	0	(50,000)
Issuance of short-term debt	0	450,000
Repayment of short-term debt	0	(1,372,746)
Withholding remittance - share-based compensation	(1,971)	(1,506)
Other	(3,190)	(4,949)
Net cash provided by (used in) financing activities	7,694	(714,823)
Change in cash and cash equivalents	351,416	(64,796)
Cash and cash equivalents at beginning of period	106,536	123,078
Cash and cash equivalents at end of period	457,952	82,085
SUPPLEMENTAL INFORMATION:
Interest paid, net of amounts capitalized	65,281	68,018
Income taxes paid, net	1,833	2,381
Southwest Gas Corporation
CASH FLOW FROM OPERATING ACTIVITIES:
Net income	135,825	134,696
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation and amortization	84,823	74,650
Deferred income taxes	40,354	39,194
Changes in undistributed stock compensation	1,211	2,955
Equity AFUDC	(1,839)	0
Changes in current assets and liabilities:
Accounts receivable, net of allowance	(28,293)	(66,816)
Accrued utility revenue	34,500	31,200
Deferred purchased gas costs	354,203	(520,219)
Accounts payable	(67,206)	(286,164)
Accrued taxes	38,621	34,473
Other current assets and liabilities	33,760	351,252
Changes in deferred charges and other assets	(22,990)	(12,891)
Changes in other liabilities and deferred credits	(25,407)	(10,942)
Net cash provided by (used in) operating activities	577,562	(228,612)
CASH FLOW FROM INVESTING ACTIVITIES:
Construction expenditures and property additions	(190,699)	(192,097)
Proceeds from the sale of property	21,376	0
Changes in customer advances	(1,658)	(6,608)
Other	200	119
Net cash provided by (used in) investing activities	(170,781)	(198,586)
CASH FLOW FROM FINANCING ACTIVITIES:
Dividends paid	(39,700)	(32,000)
Issuance of long-term debt, net	0	297,759
Change in long-term credit facility and commercial paper	0	(50,000)
Issuance of short-term debt	0	450,000
Repayment of short-term debt	0	(225,000)
Withholding remittance - share-based compensation	(1,797)	(1,292)
Other	(35)	(993)
Net cash provided by (used in) financing activities	(41,532)	438,474
Change in cash and cash equivalents	365,249	11,276
Cash and cash equivalents at beginning of period	71,154	51,823
Cash and cash equivalents at end of period	436,403	63,099
SUPPLEMENTAL INFORMATION:
Interest paid, net of amounts capitalized	31,880	29,007
Income taxes paid, net	$ 0	$ 0

CONDENSED CONSOLIDATED STATEM_8

CONDENSED CONSOLIDATED STATEMENTS OF EQUITY - Southwest - USD ($) $ in Thousands	Total	Southwest Gas Corporation	Common stock shares	Common stock shares Southwest Gas Corporation	Additional paid-in capital	Additional paid-in capital Southwest Gas Corporation	Accumulated other comprehensive loss	Accumulated other comprehensive loss Southwest Gas Corporation	Retained earnings	Retained earnings Southwest Gas Corporation
Beginning balance (in shares) at Dec. 31, 2022			67,119,000	47,482,000
Beginning balance at Dec. 31, 2022			$ 68,749	$ 49,112	$ 2,287,183	$ 1,622,969	$ (44,242)	$ (38,261)	$ 747,069	$ 935,355
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income									45,911	134,696
Share-based compensation						1,950				(287)
Net actuarial gain arising during period, less amortization of unamortized benefit plan cost, net of tax							196	196
Dividends declared to Southwest Gas Holdings, Inc.									(44,635)	(39,600)
Ending balance (in shares) at Mar. 31, 2023			71,331,000	47,482,000
Ending balance at Mar. 31, 2023		$ 2,666,130	$ 72,961	$ 49,112	2,524,631	1,624,919	(43,949)	(38,065)	742,513	1,030,164
Beginning balance (in shares) at Dec. 31, 2023	71,563,750		71,564,000	47,482,000
Beginning balance at Dec. 31, 2023			$ 73,194	$ 49,112	2,541,790	2,156,577	(43,787)	(40,548)	738,839	1,018,474
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income									87,737	135,825
Share-based compensation						(259)				(327)
Net actuarial gain arising during period, less amortization of unamortized benefit plan cost, net of tax							384	384
Dividends declared to Southwest Gas Holdings, Inc.									(44,699)	(41,699)
Ending balance (in shares) at Mar. 31, 2024	71,665,592		71,665,000	47,482,000
Ending balance at Mar. 31, 2024		$ 3,277,539	$ 73,295	$ 49,112	$ 2,547,485	$ 2,156,318	$ (46,222)	$ (40,164)	$ 781,683	$ 1,112,273

Background, Organization, and S

Background, Organization, and Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Background, Organization, and Summary of Significant Accounting Policies	Note 1 – Background, Organization, and Summary of Significant Accounting Policies Nature of Operations. Southwest Gas Holdings, Inc. (together with its subsidiaries, the “Company”) is a holding company, owning all of the shares of common stock of Southwest Gas Corporation (“Southwest” or the “natural gas distribution” segment), and through the first quarter of 2024, all of the shares of common stock of Centuri Group, Inc. (“utility infrastructure services” segment), and until February 14, 2023, all of the shares of common stock of MountainWest Pipelines Holding Company (“MountainWest” or the “pipeline and storage” segment). References throughout this document in reference to “Centuri” relate to Centuri Group, Inc., for earlier periods or more recently, to Centuri Holdings, Inc. In December 2022, the Company announced that its Board of Directors (the “Board”) unanimously determined to take strategic actions to simplify the Company’s portfolio of businesses. These actions included entering into a definitive agreement to sell 100% of MountainWest to Williams Partners Operating LLC (“Williams”) for $1.5 billion in total enterprise value, subject to certain adjustments (collectively, the “MountainWest sale”). The MountainWest sale closed on February 14, 2023. As part of this simplification strategy, the Company previously communicated that it would pursue a separation of Centuri. In April 2024, the Company announced the completion of an initial public offering (“IPO”) of Centuri Holdings, Inc. common stock, with the issuance of 14,260,000 shares ($0.01 par value) at $21.00 per share, along with a private placement of 2,591,929 shares at the same public offering price with Icahn Partners LP and Icahn Partners Master Fund LP, investment entities associated with Carl C. Icahn. The Company owns approximately 81% of Centuri following these events. Through the first quarter of 2024 and leading up to the IPO, Centuri continued to be wholly owned by Southwest Gas Holdings, Inc. Centuri continues to be consolidated as part of these financial statements, and will continue to be consolidated until such time as the conditions for consolidation are no longer met. Centuri now makes separate filings with the Securities and Exchange Commission (the “SEC”) as a public company. The Company’s common stock continues to trade under the ticker symbol “SWX,” while Centuri’s common stock trades under the ticker symbol “CTRI.” As part of the IPO and related undertakings, and to ultimately facilitate a full separation of Centuri over periods ahead, multiple agreements were executed between the Company and Centuri, including a Separation Agreement, a Tax Matters Agreement, and a Registration Rights Agreement. Centuri’s new Board of Directors includes certain overlapping board members with the Company, including Andrew W. Evans, Anne L. Mariucci, and Karen S. Haller (the Company’s Chief Executive Officer). See also Note 8 - Dispositions . Southwest is engaged in the business of purchasing, distributing, and transporting natural gas for customers in portions of Arizona, Nevada, and California. Public utility rates, practices, facilities, and service territories of Southwest are subject to regulatory oversight. The timing and amount of rate relief can materially impact results of operations. Natural gas purchases and the timing of related recoveries can materially impact liquidity, highlighted by the significant amount of cash existing as of the end of the first quarter of 2024, reflective of the collection of gas cost under purchased gas cost mechanisms as a component of customer bills. While mechanisms exist in all states in which Southwest operates, which effectively and primarily decouple authorized operating cost recovery and profitability from the volume of natural gas sold, thereby also incentivizing energy conservation, results for the natural gas distribution segment are higher during winter periods due to the seasonality incorporated in its regulatory rate structures. Centuri is a strategic utility infrastructure services company dedicated to partnering with North America’s gas and electric providers to build and maintain the energy network that powers millions of homes across the United States (“U.S.”) and Canada. Centuri derives revenue primarily from installation, replacement, repair, and maintenance of energy networks. Centuri operates in the U.S., primarily as NPL, Neuco, Linetec, and Riggs Distler, and in Canada, primarily as NPL Canada. Utility infrastructure services activity is seasonal in many of Centuri’s operating areas. Peak periods are the summer and fall months in colder climate areas, such as the northeastern and midwestern U.S. and in Canada. In warmer climate areas, such as the southwestern and southeastern U.S., utility infrastructure services activity continues year round. Basis of Presentation. The condensed consolidated financial statements of Southwest Gas Holdings, Inc. and subsidiaries and Southwest (with its subsidiaries) included herein have been prepared pursuant to the rules and regulations of the SEC. The year-end 2023 condensed balance sheet data was derived from audited financial statements. Certain information and footnote disclosures normally included in financial statements prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”) have been condensed or omitted pursuant to such rules and regulations. No substantive change has occurred with regard to the Company’s business segments on the whole during the recently completed quarter. The preparation of the condensed consolidated financial statements requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, and disclosure of contingent assets and liabilities, as of the date of the financial statements, as well as the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. In the opinion of management, all adjustments, consisting of normal recurring items and estimates necessary for a fair statement of results for the interim periods, have been made. These condensed consolidated financial statements should be read in conjunction with the consolidated financial statements and notes thereto of Southwest and the Company included in our 2023 Annual Report on Form 10-K for the fiscal year ended December 31, 2023. In the first quarter of 2023, management identified a misstatement related to its accounting for the cost of gas sold at Southwest, thereby determining that Net cost of gas sold was overstated in 2021 and 2022 by $2.3 million and $5.7 million, respectively. Southwest made an adjustment in the first quarter of 2023 to reduce Net cost of gas sold and to increase its asset balance for Deferred purchased gas cost by $8 million. Also in the first quarter of 2023, the Company identified an approximately $21 million misstatement related to its initial estimation of the loss recorded upon reclassifying MountainWest as an asset held for sale during the year ended December 31, 2022. Consequently, the impairment loss for the year ended December 31, 2022 was understated by approximately $21 million, which was corrected in the first quarter of 2023. The Company (and Southwest, with respect to Net cost of gas sold) assessed, both quantitatively and qualitatively, the impact of these items on previously issued financial statements, concluding they were not material to any earlier period or to the period of correction. Other Property and Investments. Other property and investments on Southwest’s and the Company’s Condensed Consolidated Balance Sheets includes: (Thousands of dollars) March 31, 2024 December 31, 2023 Net cash surrender value of COLI policies $ 150,182 $ 146,546 Other property 6,080 6,112 Total Southwest Gas Corporation 156,262 152,658 Non-regulated property, equipment, and intangibles 1,750,380 1,752,094 Non-regulated accumulated provision for depreciation and amortization (691,872) (675,632) Other property and investments 38,091 37,220 Total Southwest Gas Holdings, Inc. $ 1,252,861 $ 1,266,340 Held for sale. In the first quarter of 2023, the Company and Southwest concluded certain assets associated with their previous corporate headquarters met the criteria to be classified as held for sale. As a result, the Company and Southwest reclassified approximately $27 million from Other property and investments to Current assets held for sale on their respective Condensed Consolidated Balance Sheets in the first quarter of 2023. In 2023, the Company and Southwest recorded an estimated loss of $5.2 million on the assets based upon an updated fair value less costs to sell. The sale was completed in January 2024. Cash and Cash Equivalents. Cash and cash equivalents of the Company include $407.4 million and $48.9 million of money market fund investments at March 31, 2024 and December 31, 2023, respectively. Of these amounts, $407.2 million and $38.6 million at March 31, 2024 and December 31, 2023, respectively , were held by Southwest. Refer to discussion above regarding recent collections under Southwest’s purchased gas adjustment mechanisms. Noncash investing activities include capital expenditures that were not yet paid, thereby remaining in accounts payable, amounts related to which declined by approximately $20.8 million and $9.6 million during the three months ended March 31, 2024, for the Company and Southwest, respectively; and declined approximately $37.3 million and $34.2 million during the three months ended March 31, 2023, for the Company and Southwest, respectively. The Company and Southwest expanded their presentation in the first quarter 2024 to show the Change in short-term portion of credit facility and Repayment of short-term debt as separate line items within their Condensed Consolidated Statements of Cash Flows. The comparable prior-year period has been updated to reflect this change. Prepaid and other current assets. Prepaid and other current assets for the Company and Southwest include, among other things, materials and operating supplies of $80.9 million at March 31, 2024 and $83.4 million at December 31, 2023 (carried at weighted average cost). Goodwill. Goodwill is assessed as of October 1 each year for impairment, or more frequently, if circumstances indicate an impairment to the carrying value of goodwill may have occurred. The Company’s reporting units for goodwill are its operating segments, which are also its reportable segments. Since December 31, 2023, management qualitatively assessed whether events during the first three months of 2024 indicated it was more likely than not that the fair value of our reporting units was less than their carrying value, which if the case, could be an indication of a goodwill impairment. Through management’s assessments, no impairment was deemed to have occurred in the continuing segments of the Company. Goodwill in the Natural Gas Distribution and Utility Infrastructure Services segments is included in the respective Condensed Consolidated Balance Sheets as follows: (Thousands of dollars) Natural Gas Utility Infrastructure Total Company December 31, 2023 $ 11,155 $ 778,574 $ 789,729 Foreign currency translation adjustment — (2,523) (2,523) March 31, 2024 $ 11,155 $ 776,051 $ 787,206 Other Current Liabilities . Management recognizes in its balance sheets various liabilities that are expected to be settled through future cash payment within the next twelve months, including amounts payable under regulatory mechanisms, customary accrued expenses for employee compensation and benefits, declared but unpaid dividends, and miscellaneous other accrued liabilities. Other current liabilities for the Company include $44.4 million of dividends declared as of both March 31, 2024 and December 31, 2023, respectively. Also included in the balance for the Company and Southwest was $120.3 million and $87.6 million in accrued purchased gas cost as of March 31, 2024 and December 31, 2023, respectively. Other Income (Deductions). The following table provides the composition of significant items included in Other income (deductions) in Southwest’s and the Company’s Condensed Consolidated Statements of Income: Three Months Ended March 31, (Thousands of dollars) 2024 2023 Southwest Gas Corporation: Change in COLI policies $ 3,600 $ 2,400 Interest income 9,776 12,471 Equity AFUDC 1,839 — Other components of net periodic benefit cost 4,131 4,959 Miscellaneous expense (1,246) (1,387) Southwest Gas Corporation - total other income (deductions) 18,100 18,443 Centuri, MountainWest, and Southwest Gas Holdings, Inc.: Foreign transaction gain (loss) 102 (690) Equity AFUDC — 82 Equity in earnings (loss) of unconsolidated investments (113) 360 Miscellaneous income and (expense) 43 (5) Corporate and administrative (11) 270 Southwest Gas Holdings, Inc. - total other income (deductions) $ 18,121 $ 18,460 Interest income primarily relates to Southwest’s regulatory asset balances, including its deferred purchased gas cost mechanisms, the combined balance of which ranged from $970 million as of March 31, 2023 to $199 million as of March 31, 2024. Refer also to Note 2 – Components of Net Periodic Benefit Cost . Redeemable Noncontrolling Interests . In connection with the acquisition of Linetec in November 2018, the previous owner initially retained a 20% equity interest in that entity, with redemption being subject to certain rights based on the passage of time or upon the occurrence of certain triggering events. Effective in 2022, the Company, through Centuri, had the right, but not the obligation, to purchase at fair value (subject to a floor) a portion of the interest held by the previous owner, and in incremental amounts each year thereafter. In March 2022, the parties agreed to a partial redemption, reducing the noncontrolling interest to 15%, and in March 2023, agreed to a partial 5% redemption (of the 15% then remaining). Then again in April 2023, Centuri paid $39.9 million to the previous owner, thereby reducing the balance continuing to be redeemable at that time to 10% under the terms of the original agreement. In March 2024, the parties entered into an agreement to redeem the remaining 10% equity interest for $92 million, which resulted in Centuri owning all of the equity interest in Linetec as of March 31, 2024. The Company paid the $92 million in April, in accordance with the agreement. The impact of this transaction has been excluded from the Company’s Condensed Consolidated Statement of Cash Flows for the first quarter of 2024 due to its noncash nature during the period. Separately, certain members of Riggs Distler management have a 1.41% interest in Drum, which is redeemable, subject to certain rights based on the passage of time or upon the occurrence of certain triggering events. A portion of the redeemable noncontrolling interest was funded through promissory notes made to noncontrolling interest holders bearing interest at the prime rate plus 2%. During the first quarter of 2024, Centuri forgave all outstanding promissory notes and unpaid interest owed from the Riggs Distler noncontrolling interest holders and in exchange obtained 0.47% portion of the equity interest in Drum that had been funded through these notes. This comprises most of the change noted below as redemption of Drum interests during the quarter. Additionally, during the first quarter of 2024, Centuri reached an agreement to purchase 0.13% of the noncontrolling interest in Drum for $0.8 million, the majority which was accrued in March 2024 and ultimately paid in April 2024. The impact of the accrued amount has been excluded from the Company’s Condensed Consolidated Statement of Cash Flows for the first quarter of 2024 due to the noncash nature in advance of the April 2024 payment. The remaining noncontrolling interest in Drum outstanding as of March 31, 2024 was 0.81%, with Centuri owning over 99% of Drum following these events. Significant changes in the value of the redeemable noncontrolling interests, above a floor determined at the establishment date, are recognized as they occur, and the carrying value is adjusted as necessary at each reporting date. The fair value is estimated using a market approach that utilizes certain financial metrics from guideline public companies of similar industry and operating characteristics. Valuation adjustments also impact retained earnings, as reflected in the Company’s Condensed Consolidated Statement of Equity, but do not impact net income. The following depicts changes to the balances of the redeemable noncontrolling interests: (Thousands of dollars): Linetec Drum Total Balance, December 31, 2023 $ 91,978 $ 12,689 $ 104,667 Net income (loss ) attributable to redeemable noncontrolling interests (193) 18 (175) Redemption value adjustments 194 — 194 Redemption of equity interest from noncontrolling party (91,979) (5,046) (97,025) Balance, March 31, 2024 $ — $ 7,661 $ 7,661 Earnings Per Share. Basic earnings per share (“EPS”) in each period of this report were calculated by dividing net income attributable to Southwest Gas Holdings, Inc. by the weighted-average number of shares during those periods. Diluted EPS includes additional weighted-average common stock equivalents (performance shares and restricted stock units). Unless otherwise noted, the term “Earnings Per Share” refers to Basic EPS. A reconciliation of the denominator used in Basic and Diluted EPS calculations is shown in the following table: Three Months Ended March 31, (In thousands) 2024 2023 Weighted average basic shares 71,728 68,265 Effect of dilutive securities: Restricted stock units (1) 154 154 Weighted average diluted shares 71,882 68,419 (1) The number of securities included 136,000 and 132,000 performance shares during the three months ended March 31, 2024 and March 31, 2023, the total of which was derived by assuming that target performance will be achieved during the relevant performance period. Income Taxes. The C ompany’s effective tax rate was 16.3% for the three months ended March 31, 2024, compared to 37.6% for the corresponding period in 2023. The effective rate decrease was primarily due to the MountainWest sale in 2023, which also included the impact of book versus tax basis differences related to the transaction (See Note 8 - Dispositions ). Southwest’s effective tax rate was 18.2% for the three months ended March 31, 2024, compared to 18.3% for the corresponding period in 2023. These amounts varied from the statutory rate primarily as the result of the amortization of excess deferred income taxes. In April 2023, the Internal Revenue Service issued Revenue Procedure 2023-15, which provides a safe harbor method of accounting that taxpayers may use to determine whether expenditures to repair, maintain, replace, or improve natural gas transmission and distribution property must be capitalized for tax purposes. The Company and Southwest are currently reviewing this revenue procedure to determine the potential impact on their financial position, results of operations, and cash flows. Recent Accounting Standards Updates. Recently issued accounting pronouncement that will be effective in 2024 and later periods: In November 2023, the Financial Accounting Standards Board (the “FASB”) issued ASU 2023-07 “Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures.” The update, among other amendments, requires disclosure of significant segment expenses that are regularly provided to the chief operating decision maker (“CODM”) and included within each reported measure of segment profit or loss, as well as an amount and description of the composition of other segment items to reconcile to segment profit or loss, and also requires the title and position of the entity’s CODM to be disclosed. The update additionally extends certain annual disclosures to interim periods. The provisions of the update are effective for fiscal years beginning after December 15, 2023 and interim periods within the fiscal years beginning after December 15, 2024. Early adoption is permitted. Management is evaluating the impacts this update might have on the Company’s and Southwest’s disclosures. Recently issued accounting pronouncement that will be effective after 2024: In December 2023, the FASB issued ASU 2023-09 “Income Taxes (Topic 740): Improvements to Income Tax Disclosures.” The update, among other amendments, provides for enhanced income tax information primarily through changes in the rate reconciliation and income taxes paid. The update is effective for annual periods beginning after December 15, 2024; early adoption is permitted. Management is evaluating the impacts this update might have on the Company’s and Southwest’s disclosures.

Components of Net Periodic Bene

Components of Net Periodic Benefit Cost	3 Months Ended
Components of Net Periodic Benefit Cost	Mar. 31, 2024
Retirement Benefits [Abstract]
Components of Net Periodic Benefit Cost	Note 2 – Components of Net Periodic Benefit Cost Southwest has a noncontributory qualified retirement plan with defined benefits covering substantially all employees (those hired before 2022) and a separate unfunded supplemental retirement plan (“SERP”), which is limited to officers hired before 2022. Southwest also provides limited postretirement benefits other than pensions (“PBOP”) to its qualified retirees for health care, dental, and life insurance. The service cost component of net periodic benefit costs included in the table below is a component of an overhead loading process associated with the cost of labor. The overhead process ultimately results in allocation of service cost to the same accounts to which productive labor is charged. As a result, service costs become components of various accounts, primarily operations and maintenance expense, net regulated operations plant, and deferred charges and other assets for both the Company and Southwest. The other components of net periodic benefit cost are reflected in Other income (deductions) on the Condensed Consolidated Statements of Income of each entity. Variability in total net periodic benefit cost between periods, especially with regard to the Qualified Retirement Plan, is subject to changes in underlying actuarial assumptions between periods, notably the discount rate. Qualified Retirement Plan March 31, Three Months 2024 2023 (Thousands of dollars) Service cost $ 7,063 $ 6,460 Interest cost 15,097 14,791 Expected return on plan assets (21,953) (21,015) Amortization of net actuarial loss 1,577 84 Net periodic benefit cost $ 1,784 $ 320 SERP March 31, Three Months 2024 2023 (Thousands of dollars) Service cost $ 61 $ 62 Interest cost 542 531 Amortization of net actuarial loss 333 249 Net periodic benefit cost $ 936 $ 842 PBOP March 31, Three Months 2024 2023 (Thousands of dollars) Service cost $ 322 $ 317 Interest cost 794 825 Expected return on plan assets (565) (606) Amortization of prior service costs 44 44 Net periodic benefit cost $ 595 $ 580

Revenue

Revenue	3 Months Ended
Revenue	Mar. 31, 2024
Revenue from Contract with Customer [Abstract]
Revenue	Note 3 – Revenue The following information about the Company’s revenues is presented by segment. Southwest encompasses the natural gas distribution segment and Centuri encompasses the utility infrastructure services segment. Natural Gas Distribution Segment : Southwest’s operating revenues included on the Condensed Consolidated Statements of Income of both the Company and Southwest include revenue from contracts with customers, which is shown below, disaggregated by customer type, in addition to other categories of revenue: Three Months Ended (Thousands of dollars) 2024 2023 Residential $ 784,237 $ 739,313 Small commercial 206,445 174,184 Large commercial 38,016 31,091 Industrial/other 20,823 21,114 Transportation 28,687 30,543 Revenue from contracts with customers 1,078,208 996,245 Alternative revenue program revenues (deferrals) (29,433) (86,204) Other revenues (1) 4,158 4,838 Total Regulated operations revenues $ 1,052,933 $ 914,879 (1) Amounts include late fees and other miscellaneous revenues, and may also include the impact of certain regulatory mechanisms. Utility Infrastructure Services Segment : During the fourth quarter of 2023, Utility infrastructure services segment management, in connection with Centuri’s planned separation, changed its service type revenue classification to align with changes in its organizational structure, and as a result, prior year “other” revenue has been recast into gas infrastructure services or electric power infrastructure services to reflect these changes, with no impact to revenue overall. The following tables display Centuri’s revenue, reflected as Utility infrastructure services revenues on the Condensed Consolidated Statements of Income of the Company, representing revenue from contracts with customers disaggregated by service and contract types: Three Months Ended (Thousands of dollars) 2024 2023* Service Types: Gas infrastructure services $ 261,226 $ 298,640 Electric power infrastructure services 260,466 342,275 Other 6,331 12,378 Total Utility infrastructure services revenues $ 528,023 $ 653,293 *The three months ended March 31, 2023 were previously presented as: Gas infrastructure services of $297,408, Electric power infrastructure services of $233,640, and Other of $122,245. Three Months Ended (Thousands of dollars) 2024 2023 Contract Types: Master services agreement $ 443,242 $ 547,606 Bid contract 84,781 105,687 Total Utility infrastructure services revenues $ 528,023 $ 653,293 Unit price contracts $ 307,849 $ 328,527 Fixed price contracts 110,282 166,915 Time and materials contracts 109,892 157,851 Total Utility infrastructure services revenues $ 528,023 $ 653,293 The following table provides information about contracts receivable and revenue earned on contracts in progress in excess of billings (contract assets), both of which are included within Accounts receivable, net of allowances, as well as amounts billed in excess of revenue earned on contracts (contract liabilities) at Centuri, which are included in Other current liabilities as of March 31, 2024 and December 31, 2023 on the Company’s Condensed Consolidated Balance Sheets: (Thousands of dollars) March 31, 2024 December 31, 2023 Contracts receivable, net $ 287,815 $ 347,454 Revenue earned on contracts in progress in excess of billings 257,830 269,808 Amounts billed in excess of revenue earned on contracts 13,648 43,694 Revenue earned on contracts in progress in excess of billings (contract assets) that are not expected to be recognized within a year from the financial statement date are not included in the table above, and were $16.5 million as of March 31, 2024, and $0.2 million as of December 31, 2023. These non-current balances were included in Deferred charges and other assets on the Company’s Condensed Consolidated Balance Sheets. These contract assets primarily relate to Centuri’s rights to consideration for work completed, but not billed and/or approved for billing at the rep orting date, and are transferred to contracts receivable when the rights become unconditional. The amounts billed in excess of revenue earned primarily relate to the adva nce consideration received from customers for which work has not yet been completed. The decrease in the contract liability balance from December 31, 2023 to March 31, 2024 of $30 million was due t o revenue recognized during the period, net of new payments received in advance of work performed. For contracts that have an original duration of one year or less, Centuri uses the practical expedient applicable to such contracts and does not consider/compute an interest component based on the time value of money. Furthermore, because of the short duration of these contracts, Centuri has not disclosed the transaction price for the remaining performance obligations as of the end of each reporting period or when the Company expects to recognize the revenue. As of March 31, 2024, Centuri h ad 53 fi xed price contracts with an original duration of more than one year. The aggregate amount of the transaction price allocated to the unsatisfied performance obligations of these contracts as of March 31, 2024 was $277 million. C enturi expects to recognize the remaining performance obligations over approximately the next two years ; however, the timing of that recognition is largely within the control of the customer, including when the necessary materials required to complete the work are provided by the customer. Utility infrastructure services contracts receivable consists of the following: (Thousands of dollars) March 31, 2024 December 31, 2023 Billed on completed contracts and contracts in progress $ 285,896 $ 348,021 Other receivables 1,989 1,945 Contracts receivable, gross 287,885 349,966 Allowance for doubtful accounts (70) (2,512) Contracts receivable, net $ 287,815 $ 347,454

Common Stock

Common Stock	3 Months Ended
Common Stock	Mar. 31, 2024
Equity [Abstract]
Common Stock	Note 4 – Common Stock Shares of the Company’s common stock are publicly traded on the New York Stock Exchange, under the ticker symbol “SWX.” Share-based compensation related to Southwest and Centuri (for award grants prior to 2024 that continue to be subject to time-based vesting) is based on stock awards to be issued in shares of Southwest Gas Holdings, Inc. In November 2023, the Company and Southwest jointly filed an automatic shelf registration statement (File No. 333-275774), which became effective upon filing. The prior shelf registration expired in December 2023. Upon expiration of the prior shelf registration, the Company’s equity shelf program was terminated. The Company intends to enter into a similar program during 2024. During the three months ended March 31, 2024, the Company issued approximately 67,000 shares of common stock through the Omnibus Incentive Plan. Additionally, during the three months ended March 31, 2024, the Company issued 35,000 shares of common stock through the Dividend Reinvestment and Stock Purchase Plan, raising approximately $2.4 million.

Debt

Debt	3 Months Ended
Debt	Mar. 31, 2024
Debt Disclosure [Abstract]
Debt	Note 5 – Debt Long-Term Debt Long-term debt is recognized in the Company’s and Southwest’s Condensed Consolidated Balance Sheets generally at the carrying value of the obligations outstanding. Details surrounding the fair value and individual carrying values of instruments are provided in the table that follows. March 31, 2024 December 31, 2023 Carrying Fair Carrying Fair (Thousands of dollars) Southwest Gas Corporation: Debentures: 8% Series, due 2026 $ 75,000 $ 78,087 $ 75,000 $ 79,502 Medium-term notes, 7.92% series, due 2027 25,000 26,470 25,000 26,883 Medium-term notes, 6.76% series, due 2027 7,500 7,703 7,500 7,800 Notes, 5.8%, due 2027 300,000 306,630 300,000 309,180 Notes, 3.7%, due 2028 300,000 285,690 300,000 285,300 Notes, 5.45%, due 2028 300,000 304,920 300,000 307,170 Notes, 2.2%, due 2030 450,000 381,555 450,000 382,635 Notes, 4.05%, due 2032 600,000 549,840 600,000 563,940 Notes, 6.1%, due 2041 125,000 129,113 125,000 126,238 Notes, 4.875%, due 2043 250,000 215,200 250,000 214,050 Notes, 3.8%, due 2046 300,000 224,970 300,000 225,240 Notes, 4.15%, due 2049 300,000 232,860 300,000 236,370 Notes, 3.18%, due 2051 300,000 196,110 300,000 197,760 Unamortized discount and debt issuance costs (28,828) (29,594) 3,303,672 3,302,906 Revolving credit facility and commercial paper — — — — Industrial development revenue bonds: Tax-exempt Series A, due 2028 50,000 50,000 50,000 50,000 2003 Series A, due 2038 50,000 50,000 50,000 50,000 2008 Series A, due 2038 50,000 50,000 50,000 50,000 2009 Series A, due 2039 50,000 50,000 50,000 50,000 Unamortized discount and debt issuance costs (1,261) (1,363) 198,739 198,637 Less: current maturities — — Southwest Gas Corporation total long-term debt, less current maturities 3,502,411 3,501,543 Southwest Gas Holdings, Inc.: Centuri secured term loan facility 991,375 991,375 994,238 996,723 Centuri secured revolving credit facility 125,229 125,324 77,121 77,205 Other debt obligations 88,905 85,024 96,599 92,209 Unamortized discount and debt issuance costs (16,192) (17,111) Less: current maturities (42,770) (42,552) Southwest Gas Holdings, Inc. total long-term debt, less current maturities $ 4,648,958 $ 4,609,838 Southwest has a $400 million credit facility that is scheduled to expire in April 2025. Southwest designates $150 million of associated capacity as long-term debt and the remaining $250 million for working capital purposes. Interest rates for the credit facility are calculated at either the Secured Overnight Financing Rate (“SOFR”) or an “alternate base rate,” plus in each case an applicable margin that is determined based on Southwest’s senior unsecured debt rating. At March 31, 2024, the applicable margi n i s 1.125% for loans bearing interest with reference to SOFR and 0.125% for loans bearing interest with reference to the alternative base rate. At March 31, 2024, no borrowings were outstanding on the long-term portion (including under the commercial paper program), nor under the short-t erm portion of the facility. Centuri has a $1.545 billion secured revolving credit and term loan multi-currency facility. Amounts can be borrowed in either Canadian or U.S. dollars. The revolving credit facility matures on August 27, 2026 and the term loan facility matures on August 27, 2028 . Interest rates for the revolving credit facility and term loan facility are based on either a “base rate,” SOFR or the Canadian Dollar Offered Rate (“CDOR”), plus an applicable margin. The capacity of the line of credit portion of the facility is $400 million; related amounts borrowed and repaid are available to be re-borrowed. The term loan portion of the facility has a limit of $1.145 billion . The obligations under the credit agreement are secured by present and future ownership interests in substantially all direct and indirect subsidiaries of Centuri, substantially all of the tangible and intangible personal property of each borrower, certain of their direct and indirect subsidiaries, and all products, profits, and proceeds of the foregoing. Centuri’s assets securing the facility at March 31, 2024 totaled $2.4 billion . At March 31, 2024, $1.1 billion in borrowings were outstanding under Centuri’s combined secured revolving credit and term loan facility. On March 22, 2024, Centuri amended the financial covenants of its revolving credit facility to increase the maximum total net leverage ratio for the fiscal quarter ending March 31, 2024 to a ratio of 5.75 to 1.00, for the fiscal quarter ending June 30, 2024 to a ratio of 6.00 to 1.00, and for the fiscal quarter ending September 30, 2024 to a ratio of 5.75 to 1.00. In addition, this amendment increased the adjusted maximum total net leverage ratio financial covenants, which are applicable in the event that a “Qualified IPO” (as defined in the amendment) is consummated, for each of the fiscal quarters ending March 31, 2024, June 30, 2024, and September 30, 2024. The terms of the Centuri credit facility otherwise remain unchanged. Following the IPO and private placement, Centuri used approximately $316 million of proceeds to pay down $156 million of debt under the existing line of credit and $160 million of debt under the term loan portion of the facility, with the remainder intended for general corporate purposes. Short-Term Debt Southwest Gas Holdings, Inc. has a $300 million credit facility that is scheduled to expire in December 2026 and is primarily used for short-term financing needs. Interest rates for the credit facility are calculated at either SOFR or the “alternate base rate,” plus in each case an applicable margin. There was $94 million outstanding under this credit facility as of March 31, 2024. In April 2023, Southwest Gas Holdings, Inc. entered into a $550 million Term Loan Credit Agreement (the “Term Loan”) that matures in October 2024. Southwest Gas Holdings, Inc. utilized a majority of the proceeds to make an equity contribution to Southwest.

Other Comprehensive Income and

Other Comprehensive Income and Accumulated Other Comprehensive Income	3 Months Ended
	Mar. 31, 2024
Equity [Abstract]
Other Comprehensive Income and Accumulated Other Comprehensive Income	Note 6 – Other Comprehensive Income and Accumulated Other Comprehensive Income The following information presents the Company’s Other comprehensive income (loss), both before and after-tax impacts, within the Condensed Consolidated Statements of Comprehensive Income, which also impact Accumulated other comprehensive income (“AOCI”) in the Condensed Consolidated Balance Sheets and the Condensed Consolidated Statements of Equity. Related Tax Effects Allocated to Each Component of Other Comprehensive Income (Loss) Three Months Ended Three Months Ended (Thousands of dollars) Before- Tax Net-of- Before- Tax Net-of- Defined benefit pension plans: Amortization of prior service cost $ 44 $ (11) $ 33 $ 44 $ (11) $ 33 Amortization of net actuarial (gain)/loss 1,910 (459) 1,451 333 (80) 253 Regulatory adjustment (1,448) 348 (1,100) (119) 29 (90) Total other comprehensive income (loss) - Southwest Gas Corporation 506 (122) 384 258 (62) 196 Foreign currency translation adjustment (2,819) — (2,819) 97 — 97 Total other comprehensive income (loss) - Southwest Gas Holdings, Inc. $ (2,313) $ (122) $ (2,435) $ 355 $ (62) $ 293 (1) Tax amounts are calculated using a 24% rate. The Company has elected to indefinitely reinvest, in Canada, the earnings of Centuri’s Canadian subsidiaries, thus precluding deferred taxes on such earnings. As a result of this assertion, and no repatriation of earnings anticipated, the Company is not recognizing a tax effect or presenting a tax expense or benefit for currency translation adjustments reported in Other comprehensive income (loss). The following table represents a rollforward of AOCI, presented on the Company’s Condensed Consolidated Balance Sheets and its Condensed Consolidated Statements of Equity: Defined Benefit Plans Foreign Currency Items (Thousands of dollars) Before-Tax Tax After-Tax Before-Tax Tax After-Tax AOCI Beginning Balance AOCI December 31, 2023 $ (53,352) $ 12,804 $ (40,548) $ (3,239) $ — $ (3,239) $ (43,787) Foreign currency translation adjustment — — — (2,819) — (2,819) (2,819) Amortization of prior service cost (1) 44 (11) 33 — — — 33 Amortization of net actuarial loss (1) 1,910 (459) 1,451 — — — 1,451 Regulatory adjustment (2) (1,448) 348 (1,100) — — — (1,100) Net current period other comprehensive income (loss) attributable to Southwest Gas Holdings, Inc. 506 (122) 384 (2,819) — (2,819) (2,435) Ending Balance AOCI March 31, 2024 $ (52,846) $ 12,682 $ (40,164) $ (6,058) $ — $ (6,058) $ (46,222) (1) These AOCI components are included in the computation of net periodic benefit cost (see Note 2 – Components of Net Periodic Benefit Cost for additional details). (2) The regulatory adjustment represents the portion of the activity above that is expected to be recovered through rates in the future (the related regulatory asset is included in Deferred charges and other assets on the Company’s Condensed Consolidated Balance Sheets). (3) Tax amounts are calculated using a 24% rate. The following table represents a rollforward of AOCI, presented on Southwest’s Condensed Consolidated Balance Sheets: Defined Benefit Plans (Thousands of dollars) Before-Tax Tax After-Tax Beginning Balance AOCI December 31, 2023 $ (53,352) $ 12,804 $ (40,548) Amortization of prior service cost (4) 44 (11) 33 Amortization of net actuarial loss (4) 1,910 (459) 1,451 Regulatory adjustment (5) (1,448) 348 (1,100) Net current period other comprehensive income attributable to Southwest Gas Corporation 506 (122) 384 Ending Balance AOCI March 31, 2024 $ (52,846) $ 12,682 $ (40,164) (4) These AOCI components are included in the computation of net periodic benefit cost (see Note 2 – Components of Net Periodic Benefit Cost for additional details). (5) The regulatory adjustment represents the portion of the activity above that is expected to be recovered through rates in the future (the related regulatory asset is included in Deferred charges and other assets on Southwest’s Condensed Consolidated Balance Sheets). (6) Tax amounts are calculated using a 24% rate. The following table represents amounts (before income tax impacts) included in AOCI (in the tables above), that have not yet been recognized in net periodic benefit cost: (Thousands of dollars) March 31, 2024 December 31, 2023 Net actuarial loss $ (360,058) $ (361,968) Prior service cost (1,134) (1,178) Less: amount recognized in regulatory assets 308,346 309,794 Recognized in AOCI $ (52,846) $ (53,352)

Segment Information

Segment Information	3 Months Ended
Segment Information	Mar. 31, 2024
Segment Reporting [Abstract]
Segment Information	Note 7 – Segment Information The Company has two reportable segments. Southwest comprises the natural gas distribution segment and Centuri comprises the utility infrastructure services segment. As a result of the MountainWest sale in February 2023 (previously comprising the pipeline and storage segment), the information for the three months ended March 31, 2023 presented below for MountainWest reflects activity from January 1, 2023 through February 13, 2023 (the last full day of its ownership by the Company). Centuri accounts for services provided to Southwest at contractual prices. Accounts receivable for these services, which are not eliminated during consolidation, are presented in the table below: (Thousands of dollars) March 31, 2024 December 31, 2023 Centuri accounts receivable for services provided to Southwest $ 8,409 $ 13,017 In order to reconcile the table below to net income (loss) as disclosed in the Condensed Consolidated Statements of Income, an Other column is included associated with impacts of corporate and administrative activities related to Southwest Gas Holdings, Inc. The financial information pertaining to the natural gas distribution, utility infrastructure services, and pipeline and storage segments are as follows: (Thousands of dollars) Natural Gas Utility Infrastructure Pipeline and Storage Other Total Three Months Ended March 31, 2024 Revenues from external customers $ 1,052,933 $ 504,745 $ — $ — $ 1,557,678 Intersegment revenues — 23,278 — — 23,278 Total $ 1,052,933 $ 528,023 $ — $ — $ 1,580,956 Segment net income (loss) $ 135,825 $ (36,230) $ — $ (11,858) $ 87,737 Three Months Ended March 31, 2023 Revenues from external customers $ 914,879 $ 624,489 $ 35,132 $ — $ 1,574,500 Intersegment revenues — 28,804 — — 28,804 Total $ 914,879 $ 653,293 $ 35,132 $ — $ 1,603,304 Segment net income (loss) $ 134,696 $ (11,872) $ (16,288) $ (60,625) $ 45,911 The corporate and administrative activities for Southwest Gas Holdings, Inc. in the three months ending March 31, 2024 include approximately $11 million of interest expense, including amounts incurred under the $550 million Term Loan entered into in April 2023, along with $2.7 million in costs associated with the planned separation of Centuri, offset by tax benefits experienced during the quarter.

Dispositions

Dispositions	3 Months Ended
Dispositions	Mar. 31, 2024
Discontinued Operations and Disposal Groups [Abstract]
Dispositions	Note 8 - Dispositions Dispositions In December 2022, the Company announced that the Board unanimously determined to take strategic actions to simplify the Company’s portfolio of businesses. These actions included entering into a definitive agreement to sell 100% of MountainWest in an all-cash transaction to Williams for $1.5 billion in total enterprise value, subject to certain adjustments. The MountainWest sale was completed in February 2023. Additionally, the Company determined it would pursue a separation of Centuri to form a new independent publicly traded utility infrastructure services company. As discussed in Note 1 - Background, Organization, and Summary of Significant Accounting Policies , in April 2024, the Company and Centuri Holdings, Inc. announced the completion of an IPO of 12,400,000 shares of Centuri’s common stock at a price of $21.00 per share. Centuri granted the underwriters a 30-day option to purchase up to an additional 1,860,000 shares of its common stock, which was exercised. In addition, Centuri announced the concurrent private placement of an additional 2,591,929 shares at a price equal to the IPO price. Centuri’s common stock is listed on the New York Stock Exchange under the symbol “CTRI” and began trading on April 18, 2024. The net proceeds to Centuri from the IPO and the concurrent private placement, after deducting underwriting discounts and commissions of $18 million and estimated offering expenses, were approximately $329 million. Centuri used the proceeds to repay a portion (approximately $316 million) of outstanding indebtedness under its revolving credit and term loan facility, with the remainder for general corporate purposes. After completion of the IPO, and above undertakings, the Company continues to own approximately 81.0% of all ownership interests in Centuri. The Company intends to further reduce its ownership in future periods through sales of its remaining Centuri shares into the market, a distribution of Centuri shares to Company stockholders, or an exchange of Centuri shares for Southwest Gas Holdings, Inc. shares, or a combination thereof. The Company entered into several agreements with Centuri Holdings, Inc. in connection with the IPO and the planned separation, providing a framework for the relationship between the Company and Centuri after the IPO.

Pay vs Performance Disclosure

Pay vs Performance Disclosure - USD ($) $ in Thousands	3 Months Ended
Pay vs Performance Disclosure - USD ($) $ in Thousands	Mar. 31, 2024	Mar. 31, 2023
Pay vs Performance Disclosure
Net income (loss)	$ 87,737	$ 45,911

Insider Trading Arrangements

Insider Trading Arrangements	3 Months Ended
Insider Trading Arrangements	Mar. 31, 2024
Trading Arrangements, by Individual
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false

Background, Organization, and_2

Background, Organization, and Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of Operations	Nature of Operations. Southwest Gas Holdings, Inc. (together with its subsidiaries, the “Company”) is a holding company, owning all of the shares of common stock of Southwest Gas Corporation (“Southwest” or the “natural gas distribution” segment), and through the first quarter of 2024, all of the shares of common stock of Centuri Group, Inc. (“utility infrastructure services” segment), and until February 14, 2023, all of the shares of common stock of MountainWest Pipelines Holding Company (“MountainWest” or the “pipeline and storage” segment). References throughout this document in reference to “Centuri” relate to Centuri Group, Inc., for earlier periods or more recently, to Centuri Holdings, Inc. Southwest is engaged in the business of purchasing, distributing, and transporting natural gas for customers in portions of Arizona, Nevada, and California. Public utility rates, practices, facilities, and service territories of Southwest are subject to regulatory oversight. The timing and amount of rate relief can materially impact results of operations. Natural gas purchases and the timing of related recoveries can materially impact liquidity, highlighted by the significant amount of cash existing as of the end of the first quarter of 2024, reflective of the collection of gas cost under purchased gas cost mechanisms as a component of customer bills. While mechanisms exist in all states in which Southwest operates, which effectively and primarily decouple authorized operating cost recovery and profitability from the volume of natural gas sold, thereby also incentivizing energy conservation, results for the natural gas distribution segment are higher during winter periods due to the seasonality incorporated in its regulatory rate structures.
Basis of Presentation	Basis of Presentation. The condensed consolidated financial statements of Southwest Gas Holdings, Inc. and subsidiaries and Southwest (with its subsidiaries) included herein have been prepared pursuant to the rules and regulations of the SEC. The year-end 2023 condensed balance sheet data was derived from audited financial statements. Certain information and footnote disclosures normally included in financial statements prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”) have been condensed or omitted pursuant to such rules and regulations. No substantive change has occurred with regard to the Company’s business segments on the whole during the recently completed quarter. The preparation of the condensed consolidated financial statements requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, and disclosure of contingent assets and liabilities, as of the date of the financial statements, as well as the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. In the opinion of management, all adjustments, consisting of normal recurring items and estimates necessary for a fair statement of results for the interim periods, have been made. These condensed consolidated financial statements should be read in conjunction with the consolidated financial statements and notes thereto of Southwest and the Company included in our 2023 Annual Report on Form 10-K for the fiscal year ended December 31, 2023.
Held for sale	Held for sale.
Cash and Cash Equivalents	Cash and Cash Equivalents. Cash and cash equivalents of the Company include $407.4 million and $48.9 million of money market fund investments at March 31, 2024 and December 31, 2023, respectively. Of these amounts, $407.2 million and $38.6 million at March 31, 2024 and December 31, 2023, respectively , were held by Southwest. Refer to discussion above regarding recent collections under Southwest’s purchased gas adjustment mechanisms. Noncash investing activities include capital expenditures that were not yet paid, thereby remaining in accounts payable, amounts related to which declined by approximately $20.8 million and $9.6 million during the three months ended March 31, 2024, for the Company and Southwest, respectively; and declined approximately $37.3 million and $34.2 million during the three months ended March 31, 2023, for the Company and Southwest, respectively.
Prepaid and other current assets	Prepaid and other current assets. Prepaid and other current assets for the Company and Southwest include, among other things, materials and operating supplies of $80.9 million at March 31, 2024 and $83.4 million at December 31, 2023 (carried at weighted average cost).
Goodwill	Goodwill.
Other Current Liabilities	Other Current Liabilities
Redeemable Noncontrolling Interests	Significant changes in the value of the redeemable noncontrolling interests, above a floor determined at the establishment date, are recognized as they occur, and the carrying value is adjusted as necessary at each reporting date. The fair value is estimated using a market approach that utilizes certain financial metrics from guideline public companies of similar industry and operating characteristics. Valuation adjustments also impact retained earnings, as reflected in the Company’s Condensed Consolidated Statement of Equity, but do not impact net income.
Earnings Per Share	Earnings Per Share.
Income Taxes	Income Taxes. The C ompany’s effective tax rate was 16.3% for the three months ended March 31, 2024, compared to 37.6% for the corresponding period in 2023. The effective rate decrease was primarily due to the MountainWest sale in 2023, which also included the impact of book versus tax basis differences related to the transaction (See Note 8 - Dispositions ). Southwest’s effective tax rate was 18.2% for the three months ended March 31, 2024, compared to 18.3% for the corresponding period in 2023. These amounts varied from the statutory rate primarily as the result of the amortization of excess deferred income taxes. In April 2023, the Internal Revenue Service issued Revenue Procedure 2023-15, which provides a safe harbor method of accounting that taxpayers may use to determine whether expenditures to repair, maintain, replace, or improve natural gas transmission and distribution property must be capitalized for tax purposes. The Company and Southwest are currently reviewing this revenue procedure to determine the potential impact on their financial position, results of operations, and cash flows.
Recent Accounting Standards Updates	Recent Accounting Standards Updates. Recently issued accounting pronouncement that will be effective in 2024 and later periods: In November 2023, the Financial Accounting Standards Board (the “FASB”) issued ASU 2023-07 “Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures.” The update, among other amendments, requires disclosure of significant segment expenses that are regularly provided to the chief operating decision maker (“CODM”) and included within each reported measure of segment profit or loss, as well as an amount and description of the composition of other segment items to reconcile to segment profit or loss, and also requires the title and position of the entity’s CODM to be disclosed. The update additionally extends certain annual disclosures to interim periods. The provisions of the update are effective for fiscal years beginning after December 15, 2023 and interim periods within the fiscal years beginning after December 15, 2024. Early adoption is permitted. Management is evaluating the impacts this update might have on the Company’s and Southwest’s disclosures. Recently issued accounting pronouncement that will be effective after 2024: In December 2023, the FASB issued ASU 2023-09 “Income Taxes (Topic 740): Improvements to Income Tax Disclosures.” The update, among other amendments, provides for enhanced income tax information primarily through changes in the rate reconciliation and income taxes paid. The update is effective for annual periods beginning after December 15, 2024; early adoption is permitted. Management is evaluating the impacts this update might have on the Company’s and Southwest’s disclosures.

Background, Organization, and_3

Background, Organization, and Summary of Significant Accounting Policies (Tables)	3 Months Ended
	Mar. 31, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of Other Property and Investments	Other property and investments on Southwest’s and the Company’s Condensed Consolidated Balance Sheets includes: (Thousands of dollars) March 31, 2024 December 31, 2023 Net cash surrender value of COLI policies $ 150,182 $ 146,546 Other property 6,080 6,112 Total Southwest Gas Corporation 156,262 152,658 Non-regulated property, equipment, and intangibles 1,750,380 1,752,094 Non-regulated accumulated provision for depreciation and amortization (691,872) (675,632) Other property and investments 38,091 37,220 Total Southwest Gas Holdings, Inc. $ 1,252,861 $ 1,266,340
Schedule of Goodwill	Goodwill in the Natural Gas Distribution and Utility Infrastructure Services segments is included in the respective Condensed Consolidated Balance Sheets as follows: (Thousands of dollars) Natural Gas Utility Infrastructure Total Company December 31, 2023 $ 11,155 $ 778,574 $ 789,729 Foreign currency translation adjustment — (2,523) (2,523) March 31, 2024 $ 11,155 $ 776,051 $ 787,206
Schedule of Significant Items Included in Other Income (Deductions)	The following table provides the composition of significant items included in Other income (deductions) in Southwest’s and the Company’s Condensed Consolidated Statements of Income: Three Months Ended March 31, (Thousands of dollars) 2024 2023 Southwest Gas Corporation: Change in COLI policies $ 3,600 $ 2,400 Interest income 9,776 12,471 Equity AFUDC 1,839 — Other components of net periodic benefit cost 4,131 4,959 Miscellaneous expense (1,246) (1,387) Southwest Gas Corporation - total other income (deductions) 18,100 18,443 Centuri, MountainWest, and Southwest Gas Holdings, Inc.: Foreign transaction gain (loss) 102 (690) Equity AFUDC — 82 Equity in earnings (loss) of unconsolidated investments (113) 360 Miscellaneous income and (expense) 43 (5) Corporate and administrative (11) 270 Southwest Gas Holdings, Inc. - total other income (deductions) $ 18,121 $ 18,460
Schedule of Redeemable Noncontrolling Interest	The following depicts changes to the balances of the redeemable noncontrolling interests: (Thousands of dollars): Linetec Drum Total Balance, December 31, 2023 $ 91,978 $ 12,689 $ 104,667 Net income (loss ) attributable to redeemable noncontrolling interests (193) 18 (175) Redemption value adjustments 194 — 194 Redemption of equity interest from noncontrolling party (91,979) (5,046) (97,025) Balance, March 31, 2024 $ — $ 7,661 $ 7,661
Schedule of Earnings Per Share, Basic and Diluted	A reconciliation of the denominator used in Basic and Diluted EPS calculations is shown in the following table: Three Months Ended March 31, (In thousands) 2024 2023 Weighted average basic shares 71,728 68,265 Effect of dilutive securities: Restricted stock units (1) 154 154 Weighted average diluted shares 71,882 68,419 (1) The number of securities included 136,000 and 132,000

Components of Net Periodic Be_2

Components of Net Periodic Benefit Cost (Tables)	3 Months Ended
Components of Net Periodic Benefit Cost (Tables)	Mar. 31, 2024
Retirement Benefits [Abstract]
Schedule of Net Periodic Benefit Costs	The service cost component of net periodic benefit costs included in the table below is a component of an overhead loading process associated with the cost of labor. The overhead process ultimately results in allocation of service cost to the same accounts to which productive labor is charged. As a result, service costs become components of various accounts, primarily operations and maintenance expense, net regulated operations plant, and deferred charges and other assets for both the Company and Southwest. The other components of net periodic benefit cost are reflected in Other income (deductions) on the Condensed Consolidated Statements of Income of each entity. Variability in total net periodic benefit cost between periods, especially with regard to the Qualified Retirement Plan, is subject to changes in underlying actuarial assumptions between periods, notably the discount rate. Qualified Retirement Plan March 31, Three Months 2024 2023 (Thousands of dollars) Service cost $ 7,063 $ 6,460 Interest cost 15,097 14,791 Expected return on plan assets (21,953) (21,015) Amortization of net actuarial loss 1,577 84 Net periodic benefit cost $ 1,784 $ 320 SERP March 31, Three Months 2024 2023 (Thousands of dollars) Service cost $ 61 $ 62 Interest cost 542 531 Amortization of net actuarial loss 333 249 Net periodic benefit cost $ 936 $ 842 PBOP March 31, Three Months 2024 2023 (Thousands of dollars) Service cost $ 322 $ 317 Interest cost 794 825 Expected return on plan assets (565) (606) Amortization of prior service costs 44 44 Net periodic benefit cost $ 595 $ 580

Revenue (Tables)

Revenue (Tables)	3 Months Ended
Revenue (Tables)	Mar. 31, 2024
Revenue from Contract with Customer [Abstract]
Schedule of Revenue Disaggregated by Service Type and Contract Type	Southwest’s operating revenues included on the Condensed Consolidated Statements of Income of both the Company and Southwest include revenue from contracts with customers, which is shown below, disaggregated by customer type, in addition to other categories of revenue: Three Months Ended (Thousands of dollars) 2024 2023 Residential $ 784,237 $ 739,313 Small commercial 206,445 174,184 Large commercial 38,016 31,091 Industrial/other 20,823 21,114 Transportation 28,687 30,543 Revenue from contracts with customers 1,078,208 996,245 Alternative revenue program revenues (deferrals) (29,433) (86,204) Other revenues (1) 4,158 4,838 Total Regulated operations revenues $ 1,052,933 $ 914,879 (1) Amounts include late fees and other miscellaneous revenues, and may also include the impact of certain regulatory mechanisms. Three Months Ended (Thousands of dollars) 2024 2023* Service Types: Gas infrastructure services $ 261,226 $ 298,640 Electric power infrastructure services 260,466 342,275 Other 6,331 12,378 Total Utility infrastructure services revenues $ 528,023 $ 653,293 *The three months ended March 31, 2023 were previously presented as: Gas infrastructure services of $297,408, Electric power infrastructure services of $233,640, and Other of $122,245. Three Months Ended (Thousands of dollars) 2024 2023 Contract Types: Master services agreement $ 443,242 $ 547,606 Bid contract 84,781 105,687 Total Utility infrastructure services revenues $ 528,023 $ 653,293 Unit price contracts $ 307,849 $ 328,527 Fixed price contracts 110,282 166,915 Time and materials contracts 109,892 157,851 Total Utility infrastructure services revenues $ 528,023 $ 653,293
Schedule of Information about Receivables, Revenue Earned on Contracts in Progress in Excess of Billings, Which are Included Within Accounts Receivable, Net of Allowances, and Amounts Billed in Excess of Revenue Earned on Contracts	The following table provides information about contracts receivable and revenue earned on contracts in progress in excess of billings (contract assets), both of which are included within Accounts receivable, net of allowances, as well as amounts billed in excess of revenue earned on contracts (contract liabilities) at Centuri, which are included in Other current liabilities as of March 31, 2024 and December 31, 2023 on the Company’s Condensed Consolidated Balance Sheets: (Thousands of dollars) March 31, 2024 December 31, 2023 Contracts receivable, net $ 287,815 $ 347,454 Revenue earned on contracts in progress in excess of billings 257,830 269,808 Amounts billed in excess of revenue earned on contracts 13,648 43,694
Schedule of Utility Infrastructure Services Contracts Receivable	Utility infrastructure services contracts receivable consists of the following: (Thousands of dollars) March 31, 2024 December 31, 2023 Billed on completed contracts and contracts in progress $ 285,896 $ 348,021 Other receivables 1,989 1,945 Contracts receivable, gross 287,885 349,966 Allowance for doubtful accounts (70) (2,512) Contracts receivable, net $ 287,815 $ 347,454

Debt (Tables)

Debt (Tables)	3 Months Ended
Debt (Tables)	Mar. 31, 2024
Debt Disclosure [Abstract]
Schedule of Carrying Amounts and Estimated Fair Values of Long-Term Debt	Details surrounding the fair value and individual carrying values of instruments are provided in the table that follows. March 31, 2024 December 31, 2023 Carrying Fair Carrying Fair (Thousands of dollars) Southwest Gas Corporation: Debentures: 8% Series, due 2026 $ 75,000 $ 78,087 $ 75,000 $ 79,502 Medium-term notes, 7.92% series, due 2027 25,000 26,470 25,000 26,883 Medium-term notes, 6.76% series, due 2027 7,500 7,703 7,500 7,800 Notes, 5.8%, due 2027 300,000 306,630 300,000 309,180 Notes, 3.7%, due 2028 300,000 285,690 300,000 285,300 Notes, 5.45%, due 2028 300,000 304,920 300,000 307,170 Notes, 2.2%, due 2030 450,000 381,555 450,000 382,635 Notes, 4.05%, due 2032 600,000 549,840 600,000 563,940 Notes, 6.1%, due 2041 125,000 129,113 125,000 126,238 Notes, 4.875%, due 2043 250,000 215,200 250,000 214,050 Notes, 3.8%, due 2046 300,000 224,970 300,000 225,240 Notes, 4.15%, due 2049 300,000 232,860 300,000 236,370 Notes, 3.18%, due 2051 300,000 196,110 300,000 197,760 Unamortized discount and debt issuance costs (28,828) (29,594) 3,303,672 3,302,906 Revolving credit facility and commercial paper — — — — Industrial development revenue bonds: Tax-exempt Series A, due 2028 50,000 50,000 50,000 50,000 2003 Series A, due 2038 50,000 50,000 50,000 50,000 2008 Series A, due 2038 50,000 50,000 50,000 50,000 2009 Series A, due 2039 50,000 50,000 50,000 50,000 Unamortized discount and debt issuance costs (1,261) (1,363) 198,739 198,637 Less: current maturities — — Southwest Gas Corporation total long-term debt, less current maturities 3,502,411 3,501,543 Southwest Gas Holdings, Inc.: Centuri secured term loan facility 991,375 991,375 994,238 996,723 Centuri secured revolving credit facility 125,229 125,324 77,121 77,205 Other debt obligations 88,905 85,024 96,599 92,209 Unamortized discount and debt issuance costs (16,192) (17,111) Less: current maturities (42,770) (42,552) Southwest Gas Holdings, Inc. total long-term debt, less current maturities $ 4,648,958 $ 4,609,838

Other Comprehensive Income an_2

Other Comprehensive Income and Accumulated Other Comprehensive Income (Tables)	3 Months Ended
	Mar. 31, 2024
Equity [Abstract]
Schedule of Related Tax Effects Allocated to Each Component of Other Comprehensive Income (Loss)	Related Tax Effects Allocated to Each Component of Other Comprehensive Income (Loss) Three Months Ended Three Months Ended (Thousands of dollars) Before- Tax Net-of- Before- Tax Net-of- Defined benefit pension plans: Amortization of prior service cost $ 44 $ (11) $ 33 $ 44 $ (11) $ 33 Amortization of net actuarial (gain)/loss 1,910 (459) 1,451 333 (80) 253 Regulatory adjustment (1,448) 348 (1,100) (119) 29 (90) Total other comprehensive income (loss) - Southwest Gas Corporation 506 (122) 384 258 (62) 196 Foreign currency translation adjustment (2,819) — (2,819) 97 — 97 Total other comprehensive income (loss) - Southwest Gas Holdings, Inc. $ (2,313) $ (122) $ (2,435) $ 355 $ (62) $ 293 (1) Tax amounts are calculated using a 24% rate. The Company has elected to indefinitely reinvest, in Canada, the earnings of Centuri’s Canadian subsidiaries, thus precluding deferred taxes on such earnings. As a result of this assertion, and no repatriation of earnings anticipated, the Company is not recognizing a tax effect or presenting a tax expense or benefit for currency translation adjustments reported in Other comprehensive income (loss).
Schedule of Rollforward of Accumulated Other Comprehensive Income	The following table represents a rollforward of AOCI, presented on the Company’s Condensed Consolidated Balance Sheets and its Condensed Consolidated Statements of Equity: Defined Benefit Plans Foreign Currency Items (Thousands of dollars) Before-Tax Tax After-Tax Before-Tax Tax After-Tax AOCI Beginning Balance AOCI December 31, 2023 $ (53,352) $ 12,804 $ (40,548) $ (3,239) $ — $ (3,239) $ (43,787) Foreign currency translation adjustment — — — (2,819) — (2,819) (2,819) Amortization of prior service cost (1) 44 (11) 33 — — — 33 Amortization of net actuarial loss (1) 1,910 (459) 1,451 — — — 1,451 Regulatory adjustment (2) (1,448) 348 (1,100) — — — (1,100) Net current period other comprehensive income (loss) attributable to Southwest Gas Holdings, Inc. 506 (122) 384 (2,819) — (2,819) (2,435) Ending Balance AOCI March 31, 2024 $ (52,846) $ 12,682 $ (40,164) $ (6,058) $ — $ (6,058) $ (46,222) (1) These AOCI components are included in the computation of net periodic benefit cost (see Note 2 – Components of Net Periodic Benefit Cost for additional details). (2) The regulatory adjustment represents the portion of the activity above that is expected to be recovered through rates in the future (the related regulatory asset is included in Deferred charges and other assets on the Company’s Condensed Consolidated Balance Sheets). (3) Tax amounts are calculated using a 24% rate. The following table represents a rollforward of AOCI, presented on Southwest’s Condensed Consolidated Balance Sheets: Defined Benefit Plans (Thousands of dollars) Before-Tax Tax After-Tax Beginning Balance AOCI December 31, 2023 $ (53,352) $ 12,804 $ (40,548) Amortization of prior service cost (4) 44 (11) 33 Amortization of net actuarial loss (4) 1,910 (459) 1,451 Regulatory adjustment (5) (1,448) 348 (1,100) Net current period other comprehensive income attributable to Southwest Gas Corporation 506 (122) 384 Ending Balance AOCI March 31, 2024 $ (52,846) $ 12,682 $ (40,164) (4) These AOCI components are included in the computation of net periodic benefit cost (see Note 2 – Components of Net Periodic Benefit Cost for additional details). (5) The regulatory adjustment represents the portion of the activity above that is expected to be recovered through rates in the future (the related regulatory asset is included in Deferred charges and other assets on Southwest’s Condensed Consolidated Balance Sheets). (6) Tax amounts are calculated using a 24% rate.
Schedule of Amount Recognized Before Income Tax in Accumulated Other Comprehensive Income	The following table represents amounts (before income tax impacts) included in AOCI (in the tables above), that have not yet been recognized in net periodic benefit cost: (Thousands of dollars) March 31, 2024 December 31, 2023 Net actuarial loss $ (360,058) $ (361,968) Prior service cost (1,134) (1,178) Less: amount recognized in regulatory assets 308,346 309,794 Recognized in AOCI $ (52,846) $ (53,352)

Segment Information (Tables)

Segment Information (Tables)	3 Months Ended
Segment Information (Tables)	Mar. 31, 2024
Segment Reporting [Abstract]
Schedule of Accounts Receivable for Services	Accounts receivable for these services, which are not eliminated during consolidation, are presented in the table below: (Thousands of dollars) March 31, 2024 December 31, 2023 Centuri accounts receivable for services provided to Southwest $ 8,409 $ 13,017
Schedule of Segment Reporting Information	The financial information pertaining to the natural gas distribution, utility infrastructure services, and pipeline and storage segments are as follows: (Thousands of dollars) Natural Gas Utility Infrastructure Pipeline and Storage Other Total Three Months Ended March 31, 2024 Revenues from external customers $ 1,052,933 $ 504,745 $ — $ — $ 1,557,678 Intersegment revenues — 23,278 — — 23,278 Total $ 1,052,933 $ 528,023 $ — $ — $ 1,580,956 Segment net income (loss) $ 135,825 $ (36,230) $ — $ (11,858) $ 87,737 Three Months Ended March 31, 2023 Revenues from external customers $ 914,879 $ 624,489 $ 35,132 $ — $ 1,574,500 Intersegment revenues — 28,804 — — 28,804 Total $ 914,879 $ 653,293 $ 35,132 $ — $ 1,603,304 Segment net income (loss) $ 134,696 $ (11,872) $ (16,288) $ (60,625) $ 45,911

Background, Organization, and_4

Background, Organization, and Summary of Significant Accounting Policies - Narrative (Details) - USD ($)	1 Months Ended			3 Months Ended		12 Months Ended
	Apr. 30, 2024	Apr. 30, 2023	Mar. 31, 2023	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Apr. 22, 2024	Mar. 31, 2022	Nov. 30, 2018
Significant Accounting Policies [Line Items]
Common stock, par (in USD per share)				$ 1		$ 1
Decrease of net cost of gas sold				$ (629,997,000)	$ (507,537,000)
Increase in deferred purchased gas costs				(354,203,000)	535,224,000
Other property and investments adjustment				(1,252,861,000)		$ (1,266,340,000)
Current assets held for sale				0		21,377,000
Decrease of capital expenditures incurred but not yet paid				20,800,000	37,300,000
Goodwill impairment loss				0
Dividends declared but not yet paid				44,400,000		44,400,000
Accrued purchased gas cost				120,300,000		87,600,000
Deferred purchased gas costs			$ 970,000,000	$ 198,682,000	$ 970,000,000	552,885,000
Percentage of redeemable noncontrolling interest redeemed			5%
Effective income tax rate				16.30%	37.60%
Promissory Note \| Prime Rate
Significant Accounting Policies [Line Items]
Debt, basis spread on variable rate				2%
Drum
Significant Accounting Policies [Line Items]
Ownership percentage by noncontrolling owners				0.81%
Money Market Funds
Significant Accounting Policies [Line Items]
Money market fund investments				$ 407,400,000		48,900,000
Certain Assets Associated With Previous Corporate Headquarters
Significant Accounting Policies [Line Items]
Other property and investments adjustment			$ 27,000,000		$ 27,000,000
Current assets held for sale			$ 27,000,000		27,000,000
Estimated loss on disposition of assets						5,200,000
Revision of Prior Period, Error Correction, Adjustment
Significant Accounting Policies [Line Items]
Decrease of net cost of gas sold							$ 5,700,000	$ 2,300,000
Increase in deferred purchased gas costs					8,000,000
Decrease in net cost of gas sold					8,000,000
Loss on disposal adjustment					21,000,000
Impairment of asset held for sale adjustment					21,000,000
Subsequent Event
Significant Accounting Policies [Line Items]
Payments to noncontrolling interests	$ 92,000,000
Subsequent Event \| Centuri
Significant Accounting Policies [Line Items]
Ownership percentage by parent									81%
Centuri
Significant Accounting Policies [Line Items]
Payment for repurchase of redeemable noncontrolling interest		$ 39,900,000
Centuri \| Drum
Significant Accounting Policies [Line Items]
Percentage of equity interest exchanged with debt forgiveness				0.47%
Equity ownership, percentage purchased				0.13%
Payments to acquire additional interest				$ 800,000
Centuri \| Drum
Significant Accounting Policies [Line Items]
Ownership percentage by parent				99%
Centuri \| Subsequent Event \| IPO
Significant Accounting Policies [Line Items]
Sale of stock, number of shares (in shares)	14,260,000
Common stock, par (in USD per share)									$ 0.01
Shares issued, price per share (in USD per share)									$ 21
Centuri \| Subsequent Event \| Private Placement
Significant Accounting Policies [Line Items]
Sale of stock, number of shares (in shares)	2,591,929
Southwest Gas Corporation
Significant Accounting Policies [Line Items]
Decrease of net cost of gas sold				$ (629,997,000)	(501,169,000)
Increase in deferred purchased gas costs				(354,203,000)	520,219,000
Other property and investments adjustment				(156,262,000)		(152,658,000)
Current assets held for sale				0		21,376,000
Decrease of capital expenditures incurred but not yet paid				9,600,000	$ 34,200,000
Gas pipe materials and operating supplies				80,900,000		83,400,000
Deferred purchased gas costs				$ 198,682,000		552,885,000
Effective income tax rate				18.20%	18.30%
Southwest Gas Corporation \| Money Market Funds
Significant Accounting Policies [Line Items]
Money market fund investments				$ 407,200,000		$ 38,600,000
Previous Owner Of Linetec \| Linetec
Significant Accounting Policies [Line Items]
Ownership percentage by noncontrolling owners		10%		10%						15%	20%
Current partial redemption transpired				$ 92,000,000
Certain Members Of Riggs Distler Management \| Drum
Significant Accounting Policies [Line Items]
Ownership percentage by noncontrolling owners				1.41%
Discontinued Operations, Disposed of by Sale \| MountainWest
Significant Accounting Policies [Line Items]
Ownership percentage disposed							100%
Disposal consideration							$ 1,500,000,000

Background, Organization, and_5

Background, Organization, and Summary of Significant Accounting Policies - Schedule of Other Property and Investments (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Property, Plant and Equipment [Line Items]
Other property and investments	$ 38,091	$ 37,220
Non-regulated property, equipment, and intangibles	1,750,380	1,752,094
Non-regulated accumulated provision for depreciation and amortization	(691,872)	(675,632)
Total	1,252,861	1,266,340
Southwest Gas Corporation
Property, Plant and Equipment [Line Items]
Net cash surrender value of COLI policies	150,182	146,546
Other property and investments	6,080	6,112
Total	$ 156,262	$ 152,658

Background, Organization, and_6

Background, Organization, and Summary of Significant Accounting Policies - Schedule of Goodwill (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2024 USD ($)
Goodwill [Roll Forward]
Goodwill, beginning balance	$ 789,729
Foreign currency translation adjustment	(2,523)
Goodwill, ending balance	787,206
Natural Gas Distribution
Goodwill [Roll Forward]
Goodwill, beginning balance	11,155
Foreign currency translation adjustment	0
Goodwill, ending balance	11,155
Utility Infrastructure Services
Goodwill [Roll Forward]
Goodwill, beginning balance	778,574
Foreign currency translation adjustment	(2,523)
Goodwill, ending balance	$ 776,051

Background, Organization, and_7

Background, Organization, and Summary of Significant Accounting Policies - Other Income (Deductions) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Other income (deductions)
Total other income (deductions)	$ 18,121	$ 18,460
Corporate and administrative
Other income (deductions)
Total other income (deductions)	(11)	270
Southwest Gas Corporation
Other income (deductions)
Change in COLI policies	3,600	2,400
Interest income	9,776	12,471
Equity AFUDC	1,839	0
Other components of net periodic benefit cost	4,131	4,959
Miscellaneous income and (expense)	(1,246)	(1,387)
Total other income (deductions)	18,100	18,443
Centuri, MountainWest And Southwest Gas Holdings, Inc.
Other income (deductions)
Foreign transaction gain (loss)	102	(690)
Equity AFUDC	0	82
Equity in earnings (loss) of unconsolidated investments	(113)	360
Miscellaneous income and (expense)	$ 43	$ (5)

Background, Organization, and_8

Background, Organization, and Summary of Significant Accounting Policies - Schedule of Redeemable Noncontrolling Interest (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2024 USD ($)
Movement In Redeemable Noncontrolling Interest [Roll Forward]
Redeemable noncontrolling interest, beginning balance	$ 104,667
Net income (loss ) attributable to redeemable noncontrolling interests	(175)
Redemption value adjustments	194
Redemption of equity interest from noncontrolling party	(97,025)
Redeemable noncontrolling interest, ending balance	7,661
Linetec
Movement In Redeemable Noncontrolling Interest [Roll Forward]
Redeemable noncontrolling interest, beginning balance	91,978
Net income (loss ) attributable to redeemable noncontrolling interests	(193)
Redemption value adjustments	194
Redemption of equity interest from noncontrolling party	(91,979)
Redeemable noncontrolling interest, ending balance	0
Drum
Movement In Redeemable Noncontrolling Interest [Roll Forward]
Redeemable noncontrolling interest, beginning balance	12,689
Net income (loss ) attributable to redeemable noncontrolling interests	18
Redemption value adjustments	0
Redemption of equity interest from noncontrolling party	(5,046)
Redeemable noncontrolling interest, ending balance	$ 7,661

Background, Organization, and_9

Background, Organization, and Summary of Significant Accounting Policies - Schedule of Earnings Per Share (Details) - shares shares in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Weighted average basic shares (in shares)	71,728	68,265
Effect of dilutive securities:
Restricted stock units (in shares)	154	154
Weighted average diluted shares (in shares)	71,882	68,419
Number of performance share units granted (in shares)	136	132

Components of Net Periodic Be_3

Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Qualified Retirement Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 7,063	$ 6,460
Interest cost	15,097	14,791
Expected return on plan assets	(21,953)	(21,015)
Amortization of net actuarial loss	1,577	84
Net periodic benefit cost	1,784	320
SERP
Defined Benefit Plan Disclosure [Line Items]
Service cost	61	62
Interest cost	542	531
Amortization of net actuarial loss	333	249
Net periodic benefit cost	936	842
PBOP
Defined Benefit Plan Disclosure [Line Items]
Service cost	322	317
Interest cost	794	825
Expected return on plan assets	(565)	(606)
Amortization of prior service costs	44	44
Net periodic benefit cost	$ 595	$ 580

Revenue - Schedule of Regulated

Revenue - Schedule of Regulated Operations Revenues: Natural Gas Distribution Segment (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Disaggregation of Revenue [Line Items]
Total Regulated operations revenues	$ 1,052,933	$ 950,011
Southwest Gas Corporation
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1,078,208	996,245
Alternative revenue program revenues (deferrals)	(29,433)	(86,204)
Other revenues	4,158	4,838
Total Regulated operations revenues	1,052,933	914,879
Residential \| Southwest Gas Corporation
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	784,237	739,313
Small commercial \| Southwest Gas Corporation
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	206,445	174,184
Large commercial \| Southwest Gas Corporation
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	38,016	31,091
Industrial/other \| Southwest Gas Corporation
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	20,823	21,114
Transportation \| Southwest Gas Corporation
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 28,687	$ 30,543

Revenue - Schedule of Regulat_2

Revenue - Schedule of Regulated Operations Revenues: Utility Infrastructure Services Segment (Details) - Centuri - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 528,023	$ 653,293
Master services agreement
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	443,242	547,606
Bid contract
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	84,781	105,687
Unit price contracts
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	307,849	328,527
Fixed price contracts
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	110,282	166,915
Time and materials contracts
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	109,892	157,851
Gas infrastructure services
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	261,226	298,640
Gas infrastructure services \| Previously Reported
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers		297,408
Electric power infrastructure services
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	260,466	342,275
Electric power infrastructure services \| Previously Reported
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers		233,640
Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 6,331	12,378
Other \| Previously Reported
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers		$ 122,245

Revenue - Summary of Informatio

Revenue - Summary of Information about Receivables (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Revenue from Contract with Customer [Abstract]
Contracts receivable, net	$ 287,815	$ 347,454
Revenue earned on contracts in progress in excess of billings	257,830	269,808
Amounts billed in excess of revenue earned on contracts	$ 13,648	$ 43,694

Revenue - Narrative (Details)

Revenue - Narrative (Details) $ in Millions	3 Months Ended
Revenue - Narrative (Details) $ in Millions	Mar. 31, 2024 USD ($) contract	Dec. 31, 2023 USD ($)
Segment Reporting Information [Line Items]
Contract assets increase (decrease)	$ 16.5	$ 0.2
Decrease of contract liability	$ 30
Centuri
Segment Reporting Information [Line Items]
Number of contracts with original duration more than one year \| contract	53
Centuri \| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-04-01
Segment Reporting Information [Line Items]
Transaction price allocated to unsatisfied performance obligations of contracts	$ 277
Transaction price allocated to unsatisfied performance obligations of contracts, period	2 years

Revenue - Schedule of Utility I

Revenue - Schedule of Utility Infrastructure Services Contracts Receivable (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Disaggregation of Revenue [Line Items]
Contracts receivable, net	$ 287,815	$ 347,454
Utility Infrastructure Services
Disaggregation of Revenue [Line Items]
Contracts receivable, gross	287,885	349,966
Allowance for doubtful accounts	(70)	(2,512)
Contracts receivable, net	287,815	347,454
Utility Infrastructure Services \| Billed on completed contracts and contracts in progress
Disaggregation of Revenue [Line Items]
Contracts receivable, gross	285,896	348,021
Utility Infrastructure Services \| Other receivables
Disaggregation of Revenue [Line Items]
Contracts receivable, gross	$ 1,989	$ 1,945

Common Stock - Narrative (Detai

Common Stock - Narrative (Details) shares in Thousands, $ in Millions	3 Months Ended
	Mar. 31, 2024 USD ($) shares
Omnibus Incentive Plan
Class of Stock [Line Items]
Common stock issued (in shares)	67
Dividend Reinvestment and Stock Purchase Plan
Class of Stock [Line Items]
Common stock issued (in shares)	35
Common stock issued, amount \| $	$ 2.4

Debt - Schedule of Carrying Amo

Debt - Schedule of Carrying Amounts and Estimated Fair Values of Long-Term Debt (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Debt Instrument [Line Items]
Less: current maturities	$ (42,770)	$ (42,552)
Long-term debt, less current maturities	4,648,958	4,609,838
Carrying Amount
Debt Instrument [Line Items]
Unamortized discount and debt issuance costs	(16,192)	(17,111)
Less: current maturities	(42,770)	(42,552)
Long-term debt, less current maturities	4,648,958	4,609,838
Southwest Gas Corporation
Debt Instrument [Line Items]
Long-term debt, less current maturities	3,502,411	3,501,543
Southwest Gas Corporation \| Carrying Amount
Debt Instrument [Line Items]
Less: current maturities	0	0
Long-term debt, less current maturities	3,502,411	3,501,543
Centuri \| Carrying Amount \| Centuri secured revolving credit facility
Debt Instrument [Line Items]
Long-term debt, gross	125,229	77,121
Centuri \| Fair Value \| Centuri secured revolving credit facility
Debt Instrument [Line Items]
Long-term debt, gross	125,324	77,205
Debentures \| Southwest Gas Corporation \| Carrying Amount
Debt Instrument [Line Items]
Unamortized discount and debt issuance costs	(28,828)	(29,594)
Long-term debt	3,303,672	3,302,906
Revolving credit facility and commercial paper \| Southwest Gas Corporation \| Carrying Amount
Debt Instrument [Line Items]
Long-term debt	0	0
Revolving credit facility and commercial paper \| Southwest Gas Corporation \| Fair Value
Debt Instrument [Line Items]
Long-term debt	0	0
Industrial development revenue bonds \| Southwest Gas Corporation \| Carrying Amount
Debt Instrument [Line Items]
Unamortized discount and debt issuance costs	(1,261)	(1,363)
Long-term debt	198,739	198,637
Other debt obligations \| Carrying Amount
Debt Instrument [Line Items]
Long-term debt, gross	88,905	96,599
Other debt obligations \| Fair Value
Debt Instrument [Line Items]
Long-term debt, gross	$ 85,024	92,209
8% Series, due 2026 \| Debentures \| Southwest Gas Corporation
Debt Instrument [Line Items]
Debt instrument interest rate	8%
8% Series, due 2026 \| Debentures \| Southwest Gas Corporation \| Carrying Amount
Debt Instrument [Line Items]
Long-term debt, gross	$ 75,000	75,000
8% Series, due 2026 \| Debentures \| Southwest Gas Corporation \| Fair Value
Debt Instrument [Line Items]
Long-term debt, gross	$ 78,087	79,502
Medium-term notes, 7.92% series, due 2027 \| Debentures \| Southwest Gas Corporation
Debt Instrument [Line Items]
Debt instrument interest rate	7.92%
Medium-term notes, 7.92% series, due 2027 \| Debentures \| Southwest Gas Corporation \| Carrying Amount
Debt Instrument [Line Items]
Long-term debt, gross	$ 25,000	25,000
Medium-term notes, 7.92% series, due 2027 \| Debentures \| Southwest Gas Corporation \| Fair Value
Debt Instrument [Line Items]
Long-term debt, gross	$ 26,470	26,883
Medium-term notes, 6.76% series, due 2027 \| Debentures \| Southwest Gas Corporation
Debt Instrument [Line Items]
Debt instrument interest rate	6.76%
Medium-term notes, 6.76% series, due 2027 \| Debentures \| Southwest Gas Corporation \| Carrying Amount
Debt Instrument [Line Items]
Long-term debt, gross	$ 7,500	7,500
Medium-term notes, 6.76% series, due 2027 \| Debentures \| Southwest Gas Corporation \| Fair Value
Debt Instrument [Line Items]
Long-term debt, gross	$ 7,703	7,800
Notes, 5.8%, due 2027 \| Debentures \| Southwest Gas Corporation
Debt Instrument [Line Items]
Debt instrument interest rate	5.80%
Notes, 5.8%, due 2027 \| Debentures \| Southwest Gas Corporation \| Carrying Amount
Debt Instrument [Line Items]
Long-term debt, gross	$ 300,000	300,000
Notes, 5.8%, due 2027 \| Debentures \| Southwest Gas Corporation \| Fair Value
Debt Instrument [Line Items]
Long-term debt, gross	$ 306,630	309,180
Notes, 3.7%, due 2028 \| Debentures \| Southwest Gas Corporation
Debt Instrument [Line Items]
Debt instrument interest rate	3.70%
Notes, 3.7%, due 2028 \| Debentures \| Southwest Gas Corporation \| Carrying Amount
Debt Instrument [Line Items]
Long-term debt, gross	$ 300,000	300,000
Notes, 3.7%, due 2028 \| Debentures \| Southwest Gas Corporation \| Fair Value
Debt Instrument [Line Items]
Long-term debt, gross	$ 285,690	285,300
Notes, 5.45%, due 2028 \| Debentures \| Southwest Gas Corporation
Debt Instrument [Line Items]
Debt instrument interest rate	5.45%
Notes, 5.45%, due 2028 \| Debentures \| Southwest Gas Corporation \| Carrying Amount
Debt Instrument [Line Items]
Long-term debt, gross	$ 300,000	300,000
Notes, 5.45%, due 2028 \| Debentures \| Southwest Gas Corporation \| Fair Value
Debt Instrument [Line Items]
Long-term debt, gross	$ 304,920	307,170
Notes, 2.2%, due 2030 \| Debentures \| Southwest Gas Corporation
Debt Instrument [Line Items]
Debt instrument interest rate	2.20%
Notes, 2.2%, due 2030 \| Debentures \| Southwest Gas Corporation \| Carrying Amount
Debt Instrument [Line Items]
Long-term debt, gross	$ 450,000	450,000
Notes, 2.2%, due 2030 \| Debentures \| Southwest Gas Corporation \| Fair Value
Debt Instrument [Line Items]
Long-term debt, gross	$ 381,555	382,635
Notes, 4.05%, due 2032 \| Debentures \| Southwest Gas Corporation
Debt Instrument [Line Items]
Debt instrument interest rate	4.05%
Notes, 4.05%, due 2032 \| Debentures \| Southwest Gas Corporation \| Carrying Amount
Debt Instrument [Line Items]
Long-term debt, gross	$ 600,000	600,000
Notes, 4.05%, due 2032 \| Debentures \| Southwest Gas Corporation \| Fair Value
Debt Instrument [Line Items]
Long-term debt, gross	$ 549,840	563,940
Notes, 6.1%, due 2041 \| Debentures \| Southwest Gas Corporation
Debt Instrument [Line Items]
Debt instrument interest rate	6.10%
Notes, 6.1%, due 2041 \| Debentures \| Southwest Gas Corporation \| Carrying Amount
Debt Instrument [Line Items]
Long-term debt, gross	$ 125,000	125,000
Notes, 6.1%, due 2041 \| Debentures \| Southwest Gas Corporation \| Fair Value
Debt Instrument [Line Items]
Long-term debt, gross	$ 129,113	126,238
Notes, 4.875%, due 2043 \| Debentures \| Southwest Gas Corporation
Debt Instrument [Line Items]
Debt instrument interest rate	4.875%
Notes, 4.875%, due 2043 \| Debentures \| Southwest Gas Corporation \| Carrying Amount
Debt Instrument [Line Items]
Long-term debt, gross	$ 250,000	250,000
Notes, 4.875%, due 2043 \| Debentures \| Southwest Gas Corporation \| Fair Value
Debt Instrument [Line Items]
Long-term debt, gross	$ 215,200	214,050
Notes, 3.8%, due 2046 \| Debentures \| Southwest Gas Corporation
Debt Instrument [Line Items]
Debt instrument interest rate	3.80%
Notes, 3.8%, due 2046 \| Debentures \| Southwest Gas Corporation \| Carrying Amount
Debt Instrument [Line Items]
Long-term debt, gross	$ 300,000	300,000
Notes, 3.8%, due 2046 \| Debentures \| Southwest Gas Corporation \| Fair Value
Debt Instrument [Line Items]
Long-term debt, gross	$ 224,970	225,240
Notes, 4.15%, due 2049 \| Debentures \| Southwest Gas Corporation
Debt Instrument [Line Items]
Debt instrument interest rate	4.15%
Notes, 4.15%, due 2049 \| Debentures \| Southwest Gas Corporation \| Carrying Amount
Debt Instrument [Line Items]
Long-term debt, gross	$ 300,000	300,000
Notes, 4.15%, due 2049 \| Debentures \| Southwest Gas Corporation \| Fair Value
Debt Instrument [Line Items]
Long-term debt, gross	$ 232,860	236,370
Notes, 3.18%, due 2051 \| Debentures \| Southwest Gas Corporation
Debt Instrument [Line Items]
Debt instrument interest rate	3.18%
Notes, 3.18%, due 2051 \| Debentures \| Southwest Gas Corporation \| Carrying Amount
Debt Instrument [Line Items]
Long-term debt, gross	$ 300,000	300,000
Notes, 3.18%, due 2051 \| Debentures \| Southwest Gas Corporation \| Fair Value
Debt Instrument [Line Items]
Long-term debt, gross	196,110	197,760
Tax-exempt Series A, due 2028 \| Industrial development revenue bonds \| Southwest Gas Corporation \| Carrying Amount
Debt Instrument [Line Items]
Long-term debt, gross	50,000	50,000
Tax-exempt Series A, due 2028 \| Industrial development revenue bonds \| Southwest Gas Corporation \| Fair Value
Debt Instrument [Line Items]
Long-term debt, gross	50,000	50,000
2003 Series A, due 2038 \| Industrial development revenue bonds \| Southwest Gas Corporation \| Carrying Amount
Debt Instrument [Line Items]
Long-term debt, gross	50,000	50,000
2003 Series A, due 2038 \| Industrial development revenue bonds \| Southwest Gas Corporation \| Fair Value
Debt Instrument [Line Items]
Long-term debt, gross	50,000	50,000
2008 Series A, due 2038 \| Industrial development revenue bonds \| Southwest Gas Corporation \| Carrying Amount
Debt Instrument [Line Items]
Long-term debt, gross	50,000	50,000
2008 Series A, due 2038 \| Industrial development revenue bonds \| Southwest Gas Corporation \| Fair Value
Debt Instrument [Line Items]
Long-term debt, gross	50,000	50,000
2009 Series A, due 2039 \| Industrial development revenue bonds \| Southwest Gas Corporation \| Carrying Amount
Debt Instrument [Line Items]
Long-term debt, gross	50,000	50,000
2009 Series A, due 2039 \| Industrial development revenue bonds \| Southwest Gas Corporation \| Fair Value
Debt Instrument [Line Items]
Long-term debt, gross	50,000	50,000
Centuri secured term loan facility \| Secured Debt \| Centuri \| Carrying Amount
Debt Instrument [Line Items]
Long-term debt, gross	991,375	994,238
Centuri secured term loan facility \| Secured Debt \| Centuri \| Fair Value
Debt Instrument [Line Items]
Long-term debt, gross	$ 991,375	$ 996,723

Debt - Narrative (Details)

Debt - Narrative (Details)	1 Months Ended	3 Months Ended
Debt - Narrative (Details)	Apr. 30, 2024 USD ($)	Mar. 31, 2024 USD ($)	Mar. 22, 2024	Dec. 31, 2023 USD ($)	Apr. 30, 2023 USD ($)
Debt Instrument [Line Items]
Short-term debt		$ 644,000,000		$ 628,500,000
SWH term loan facility \| Secured Debt
Debt Instrument [Line Items]
Debt instrument face amount					$ 550,000,000
Centuri \| Subsequent Event
Debt Instrument [Line Items]
Repayments of debt	$ 316,000,000
Centuri \| Centuri Secured Term Loan Facility And Revolving Credit Facility
Debt Instrument [Line Items]
Credit facility maximum borrowing capacity		1,545,000,000
Borrowings outstanding under facility		1,100,000,000
Centuri \| Centuri secured term loan facility
Debt Instrument [Line Items]
Credit facility maximum borrowing capacity		1,145,000,000
Centuri \| Centuri secured term loan facility \| Subsequent Event
Debt Instrument [Line Items]
Repayments of debt	160,000,000
$400 Million Credit Facility \| Southwest Gas Corporation
Debt Instrument [Line Items]
Credit facility maximum borrowing capacity		400,000,000
Line of credit designated as long term debt		150,000,000
Line of credit designated for working capital purposes		250,000,000
Long-term debt outstanding		0
Short-term debt		$ 0
$400 Million Credit Facility \| Southwest Gas Corporation \| Secured Overnight Financing Rate (SOFR)
Debt Instrument [Line Items]
Debt, basis spread on variable rate		1.125%
$400 Million Credit Facility \| Southwest Gas Corporation \| Alternative base rate
Debt Instrument [Line Items]
Debt, basis spread on variable rate		0.125%
Centuri secured revolving credit facility \| Centuri \| Subsequent Event
Debt Instrument [Line Items]
Repayments of debt	$ 156,000,000
Centuri secured revolving credit facility \| Centuri \| Line of Credit
Debt Instrument [Line Items]
Credit facility maximum borrowing capacity		$ 400,000,000
Revolving Credit Facility \| Centuri \| Line of Credit
Debt Instrument [Line Items]
Debt secured by assets		2,400,000,000
Revolving Credit Facility \| Centuri \| Line of Credit \| Fiscal quarter ending March 31, 2024
Debt Instrument [Line Items]
Debt covenant, net leverage ratio			5.75
Revolving Credit Facility \| Centuri \| Line of Credit \| Fiscal quarter ending June 30, 2024
Debt Instrument [Line Items]
Debt covenant, net leverage ratio			6
Revolving Credit Facility \| Centuri \| Line of Credit \| Fiscal quarter ending September 30, 2024
Debt Instrument [Line Items]
Debt covenant, net leverage ratio			5.75
$300 Million Credit Facility
Debt Instrument [Line Items]
Line of credit facility, maximum commitment amount		300,000,000
Short-term debt		$ 94,000,000

Other Comprehensive Income an_3

Other Comprehensive Income and Accumulated Other Comprehensive Income - Related Tax Effects Allocated to OCI (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), before tax	$ (2,313)	$ 355
Other comprehensive income (loss), tax	(122)	(62)
Total other comprehensive income (loss), net of tax	$ (2,435)	$ 293
Statutory income tax rate	24%	24%
Southwest Gas Corporation
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), before tax	$ 506	$ 258
Other comprehensive income (loss), tax	(122)	(62)
Total other comprehensive income (loss), net of tax	384	196
Amortization of prior service cost
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), before tax	44
Other comprehensive income (loss), tax	(11)
Total other comprehensive income (loss), net of tax	33
Amortization of prior service cost \| Southwest Gas Corporation
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification from AOCI, before Tax	44	44
Reclassification from AOCI, tax	(11)	(11)
Reclassification from AOCI, net of tax	33	33
Amortization of net actuarial (gain)/loss
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), before tax	1,910
Other comprehensive income (loss), tax	(459)
Total other comprehensive income (loss), net of tax	1,451
Amortization of net actuarial (gain)/loss \| Southwest Gas Corporation
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification from AOCI, before Tax	1,910	333
Reclassification from AOCI, tax	(459)	(80)
Reclassification from AOCI, net of tax	1,451	253
Regulatory adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), before tax	(1,448)
Other comprehensive income (loss), tax	348
Total other comprehensive income (loss), net of tax	(1,100)
Regulatory adjustment \| Southwest Gas Corporation
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification from AOCI, before Tax	(1,448)	(119)
Reclassification from AOCI, tax	348	29
Reclassification from AOCI, net of tax	(1,100)	(90)
Foreign currency translation adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss) before reclassifications, before tax	(2,819)	97
Other comprehensive income (loss) before reclassifications, tax	0	0
Other comprehensive income (loss) before reclassifications, net of tax	$ (2,819)	$ 97

Other Comprehensive Income an_4

Other Comprehensive Income and Accumulated Other Comprehensive Income - AOCI Rollforward (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance, attributable to parent	$ 3,310,036
Other comprehensive income (loss), before tax	(2,313)	$ 355
Other comprehensive income (loss), tax	(122)	(62)
Total other comprehensive income (loss), net of tax	(2,435)	$ 293
Ending balance, attributable to parent	$ 3,356,241
Statutory income tax rate	24%	24%
Southwest Gas Corporation
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance, attributable to parent	$ 3,183,615
Other comprehensive income (loss), before tax	506	$ 258
Other comprehensive income (loss), tax	(122)	(62)
Total other comprehensive income (loss), net of tax	384	196
Ending balance	3,277,539	2,666,130
Ending balance, attributable to parent	3,277,539
Defined Benefit Plans
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance, before tax	(53,352)
Beginning balance, tax (expense) benefit	12,804
Beginning balance	(40,548)
Other comprehensive income (loss), before tax	506
Other comprehensive income (loss), tax	(122)
Total other comprehensive income (loss), net of tax	384
Ending balance, before tax	(52,846)
Ending balance, tax (expense) benefit	12,682
Ending balance	(40,164)
Defined Benefit Plans \| Southwest Gas Corporation
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance, attributable to parent, before tax	(53,352)
Beginning balance, attributable to parent, tax (expense) benefit	12,804
Beginning balance, attributable to parent	(40,548)
Other comprehensive income (loss), before tax	506
Other comprehensive income (loss), tax	(122)
Total other comprehensive income (loss), net of tax	384
Ending balance, attributable to parent, before tax	(52,846)
Ending balance, attributable to parent, tax (expense) benefit	12,682
Ending balance, attributable to parent	(40,164)
Amortization of prior service cost
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other comprehensive income (loss), before tax	44
Other comprehensive income (loss), tax	(11)
Total other comprehensive income (loss), net of tax	33
Amortization of prior service cost \| Southwest Gas Corporation
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Reclassification from AOCI, before Tax	44	44
Reclassification from AOCI, tax	(11)	(11)
Reclassification from AOCI, net of tax	33	33
Amortization of net actuarial loss
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other comprehensive income (loss), before tax	1,910
Other comprehensive income (loss), tax	(459)
Total other comprehensive income (loss), net of tax	1,451
Amortization of net actuarial loss \| Southwest Gas Corporation
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Reclassification from AOCI, before Tax	1,910	333
Reclassification from AOCI, tax	(459)	(80)
Reclassification from AOCI, net of tax	1,451	253
Regulatory adjustment \| Southwest Gas Corporation
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other comprehensive income (loss), before tax	(1,448)
Other comprehensive income (loss), tax	348
Total other comprehensive income (loss), net of tax	(1,100)
Foreign Currency Items
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance, before tax	(3,239)
Beginning balance, tax (expense) benefit	0
Beginning balance	(3,239)
Other comprehensive income (loss) before reclassifications, before tax	(2,819)
Other comprehensive income (loss) before reclassifications, tax	0
Other comprehensive income (loss) before reclassifications, net of tax	(2,819)
Ending balance, before tax	(6,058)
Ending balance, tax (expense) benefit	0
Ending balance	(6,058)
AOCI Including Portion Attributable to Noncontrolling Interest
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other comprehensive income (loss) before reclassifications, net of tax	(2,435)
AOCI
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(43,787)	(44,242)
Ending balance	(46,222)	(43,949)
AOCI \| Southwest Gas Corporation
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(40,548)	(38,261)
Ending balance	$ (40,164)	$ (38,065)

Other Comprehensive Income an_5

Other Comprehensive Income and Accumulated Other Comprehensive Income - Amounts Recognized Before Tax, Defined Benefit Plans (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Equity [Abstract]
Net actuarial loss	$ (360,058)	$ (361,968)
Prior service cost	(1,134)	(1,178)
Less: amount recognized in regulatory assets	308,346	309,794
Recognized in AOCI	$ (52,846)	$ (53,352)

Segment Information - Narrative

Segment Information - Narrative (Details)	3 Months Ended
Segment Information - Narrative (Details)	Mar. 31, 2024 USD ($) segment	Mar. 31, 2023 USD ($)	Apr. 30, 2023 USD ($)
Segment Reporting [Abstract]
Number of reportable segments \| segment	2
Segment Reporting Information [Line Items]
Interest expense	$ 71,605,000	$ 77,334,000
SWH term loan facility \| Secured Debt
Segment Reporting Information [Line Items]
Interest expense	11,000,000
Debt instrument face amount			$ 550,000,000
Corporate and administrative
Segment Reporting Information [Line Items]
Spinoff transaction costs	$ 2,700,000

Segment Information - Accounts

Segment Information - Accounts Receivable Not Eliminated During Consolidation (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Segment Reporting Information [Line Items]
Centuri accounts receivable for services provided to Southwest	$ 843,133	$ 886,549
Centuri \| Related Party
Segment Reporting Information [Line Items]
Centuri accounts receivable for services provided to Southwest	$ 8,409	$ 13,017

Segment Information - Schedule

Segment Information - Schedule of Segment Reporting Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Segment Reporting Information [Line Items]
Revenues	$ 1,580,956	$ 1,603,304
Net income (loss)	87,737	45,911
Operating Segments
Segment Reporting Information [Line Items]
Revenues	1,557,678	1,574,500
Intersegment Eliminations
Segment Reporting Information [Line Items]
Revenues	(23,278)	(28,804)
Other
Segment Reporting Information [Line Items]
Net income (loss)	(11,858)	(60,625)
Natural Gas Distribution
Segment Reporting Information [Line Items]
Revenues	1,052,933	914,879
Natural Gas Distribution \| Operating Segments
Segment Reporting Information [Line Items]
Revenues	1,052,933	914,879
Net income (loss)	135,825	134,696
Natural Gas Distribution \| Intersegment Eliminations
Segment Reporting Information [Line Items]
Revenues	0	0
Utility Infrastructure Services
Segment Reporting Information [Line Items]
Revenues	528,023	653,293
Utility Infrastructure Services \| Operating Segments
Segment Reporting Information [Line Items]
Revenues	504,745	624,489
Net income (loss)	(36,230)	(11,872)
Utility Infrastructure Services \| Intersegment Eliminations
Segment Reporting Information [Line Items]
Revenues	(23,278)	(28,804)
Pipeline and Storage
Segment Reporting Information [Line Items]
Revenues	0	35,132
Pipeline and Storage \| Operating Segments
Segment Reporting Information [Line Items]
Revenues	0	35,132
Net income (loss)	0	(16,288)
Pipeline and Storage \| Intersegment Eliminations
Segment Reporting Information [Line Items]
Revenues	$ 0	$ 0

Dispositions (Details)

Dispositions (Details) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended
	Apr. 30, 2024	Apr. 22, 2024	Dec. 31, 2022
Subsequent Event \| Centuri
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Ownership percentage by parent		81%
Centuri \| Subsequent Event
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Repayments of debt	$ 316
Centuri \| IPO \| Subsequent Event
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sale of stock, number of shares (in shares)	14,260,000
Sale of stock, price per share (in USD per share)		$ 21
Period of option to purchase for underwriters	30 days
Stock issuance costs	$ 18
Net proceeds from sale of stock	$ 329
Centuri \| Private Placement \| Subsequent Event
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sale of stock, number of shares (in shares)	2,591,929
Centuri \| Over-Allotment Option \| Subsequent Event
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sale of stock, number of shares (in shares)	1,860,000
Centuri \| IPO, Excluding Over-Allotment Option \| Subsequent Event
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sale of stock, number of shares (in shares)	12,400,000
Disposed of by Sale \| MountainWest
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Ownership percentage disposed			100%
Disposal consideration			$ 1,500

Uncategorized Items - swx-20240

Label	Element	Value
Cash And Cash Equivalents Included In Current Assets Held For Sale	swx_CashAndCashEquivalentsIncludedInCurrentAssetsHeldForSale	$ 0
Cash And Cash Equivalents Included In Current Assets Held For Sale	swx_CashAndCashEquivalentsIncludedInCurrentAssetsHeldForSale	$ 23,803,000