The Travelers Companies, Inc. (TRV) 10-K13 Feb 202019 FY Annual reportFinancial data

Company Profile

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
Document and Entity Information - USD ($)	Dec. 31, 2019	Feb. 07, 2020	Jun. 28, 2019
Document and Entity Information
Document type	10-K
Document annual report	true
Document period end date	Dec. 31, 2019
Document transition report	false
Entity file number	001-10898
Registrant name	Travelers Companies, Inc.
Entity incorporation, state	MN
Entity tax identification number	41-0518860
Entity address, address line one	485 Lexington Avenue
Entity address, city	New York
Entity address, state	NY
Entity address, postal zip code	10017
City area code	917
Local phone number	778-6000
Title of 12(b) security	Common stock, without par value
Trading symbol	TRV
Security exchange name	NYSE
Well-known seasoned issuer	Yes
Voluntary filers	No
Entity current reporting status	Yes
Entity interactive data current	Yes
Filer category	Large Accelerated Filer
Entity small business	false
Entity emerging growth company	false
Entity shell company	false
Entity public float			$ 38,824,535,607
Common stock shares outstanding		255,030,905
Central index key	0000086312
Current fiscal year end date	--12-31
Amendment flag	false
Document fiscal year focus	2019
Document fiscal period focus	FY

Consolidated Statement of Incom

Consolidated Statement of Income - USD ($) shares in Millions, $ in Millions		3 Months Ended								12 Months Ended
		Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenues
Premiums										$ 28,272	$ 27,059	$ 25,683
Net investment income										2,468	2,474	2,397
Fee income										459	432	447
Net realized investment gains	[1]									113	114	216
Other revenues										269	203	159
Total revenues		$ 8,063	$ 8,013	$ 7,834	$ 7,671	$ 7,796	$ 7,723	$ 7,477	$ 7,286	31,581	30,282	28,902
Claims and expenses
Claims and claim adjustment expenses										19,133	18,291	17,467
Amortization of deferred acquisition costs										4,601	4,381	4,166
General and administrative expenses										4,365	4,297	4,170
Interest expense										344	352	369
Total claims and expenses		6,989	7,581	7,169	6,704	7,050	6,917	6,846	6,508	28,443	27,321	26,172
Income before income taxes		1,074	432	665	967	746	806	631	778	3,138	2,961	2,730
Income tax expense		201	36	108	171	125	97	107	109	516	438	674
Net income		$ 873	$ 396	$ 557	$ 796	$ 621	$ 709	$ 524	$ 669	$ 2,622	$ 2,523	$ 2,056
Net income per share
Basic (in dollars per share)		$ 3.37	$ 1.52	$ 2.11	$ 3.01	$ 2.33	$ 2.65	$ 1.93	$ 2.45	$ 10.01	$ 9.37	$ 7.39
Diluted (in dollars per share)		$ 3.35	$ 1.50	$ 2.10	$ 2.99	$ 2.32	$ 2.62	$ 1.92	$ 2.42	$ 9.92	$ 9.28	$ 7.33
Weighted average number of common shares outstanding
Basic (in shares)										260	267.4	276
Diluted (in shares)										262.3	269.8	278.6

[1]	Total other-than-temporary impairment (OTTI) losses were $(3) million , $(1) million and $(13) million for the years ended December 31, 2019 , 2018 and 2017 , respectively. Of total OTTI, credit losses of $(4) million , $(1) million and $(14) million for the years ended December 31, 2019 , 2018 and 2017 , respectively, were recognized in net realized investment gains. In addition, unrealized gains (losses) from other changes in total OTTI of $1 million , $0 million and $1 million for the years ended December 31, 2019 , 2018 and 2017 , respectively, were recognized in other comprehensive income (loss) as part of changes in net unrealized gains (losses) on investment securities having credit losses recognized in the consolidated statement of income.

Consolidated Statement of Inc_2

Consolidated Statement of Income Parentheticals - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Statement [Abstract]
Total other-than-temporary impairment losses	$ (3)	$ (1)	$ (13)
Other-than-temporary impairment, credit losses recognized in net realized investment gains	(4)	(1)
Other-than-temporary impairment, credit losses recognized in net realized investment gains			(14)
Unrealized losses from other changes in total other-than-temporary impairments recognized in other comprehensive income (loss) as part of changes in net unrealized gains (losses) on investment securities having credit losses recognized in the consolidated statement of income		$ 0
Unrealized gains from other changes in total other-than-temporary impairments recognized in other comprehensive income (loss) as part of changes in net unrealized gains (losses) on investment securities having credit losses recognized in the consolidated statement of income	$ 1		$ 1

Consolidated Statement of Compr

Consolidated Statement of Comprehensive Income - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 873	$ 396	$ 557	$ 796	$ 621	$ 709	$ 524	$ 669	$ 2,622	$ 2,523	$ 2,056
Other comprehensive income (loss):
Changes in net unrealized gains (losses) on investment securities having no credit losses recognized in the consolidated statement of income									2,994	(1,489)	294
Changes in net unrealized gains (losses) on investment securities having credit losses recognized in the consolidated statement of income									(4)	(27)	8
Net changes in benefit plan assets and obligations									33	(56)	29
Net changes in unrealized foreign currency translation									117	(247)	191
Other comprehensive income (loss) before income taxes									3,140	(1,819)	522
Income tax expense (benefit)									641	(349)	110
Other comprehensive income (loss), net of taxes									2,499	(1,470)	412
Comprehensive income									$ 5,121	$ 1,053	$ 2,468

Consolidated Balance Sheet

Consolidated Balance Sheet - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Assets
Fixed maturities, available for sale, at fair value (amortized cost $65,281 and $63,601)	$ 68,134	$ 63,464
Equity securities, at fair value (cost $376 and $382)	425	368
Real estate investments	963	904
Short-term securities	4,943	3,985
Other investments	3,419	3,557
Total investments	77,884	72,278
Cash	494	373
Investment income accrued	618	624
Premiums receivable	7,909	7,506
Reinsurance recoverables	8,235	8,370
Ceded unearned premiums	689	578
Deferred acquisition costs	2,273	2,120
Deferred taxes	0	445
Contractholder receivables	4,619	4,785
Goodwill	3,961	3,937
Other intangible assets	330	345
Other assets	3,110	2,872
Total assets	110,122	104,233
Liabilities
Claims and claim adjustment expense reserves	51,849	50,668
Unearned premium reserves	14,604	13,555
Contractholder payables	4,619	4,785
Payables for reinsurance premiums	363	289
Deferred taxes	137	0
Debt	6,558	6,564
Other liabilities	6,049	5,478
Total liabilities	84,179	81,339
Shareholders’ equity
Common stock (1,750.0 shares authorized; 255.5 and 263.7 shares issued, 255.5 and 263.6 shares outstanding)	23,469	23,144
Retained earnings	36,977	35,204
Accumulated other comprehensive income (loss)	640	(1,859)
Treasury stock, at cost (522.1 and 510.9 shares)	(35,143)	(33,595)
Total shareholders’ equity	25,943	22,894	$ 23,731
Total liabilities and shareholders’ equity	$ 110,122	$ 104,233

Consolidated Balance Sheet Pare

Consolidated Balance Sheet Parentheticals - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Fixed maturities, available for sale, amortized cost	$ 65,281	$ 63,601
Equity securities, cost	$ 376	$ 382
Common stock, shares authorized (in shares)	1,750,000,000	1,750,000,000
Common stock, shares issued (in shares)	255,500,000	263,700,000
Common stock, shares outstanding (in shares)	255,500,000	263,600,000
Treasury stock, at cost, shares (in shares)	522,100,000	510,900,000

Consolidated Statement of Chang

Consolidated Statement of Changes in Shareholders' Equity - USD ($) shares in Millions, $ in Millions	Total	Common stock [Member]	Retained earnings [Member]	Accumulated other comprehensive income (loss), net of tax [Member]	Treasury stock, at cost [Member]	Common shares outstanding [Member]
Balance, beginning of year at Dec. 31, 2016		$ 22,614	$ 32,196	$ (755)	$ (30,834)
Shareholders' Equity [Roll Forward]
Employee share-based compensation		136
Compensation amortization under share-based plans and other changes		136
Net income	$ 2,056		2,056
Dividends			(789)
Other			(1)
Other comprehensive income (loss)	412			412
Treasury stock acquired — share repurchase authorization					(1,378)
Net shares acquired related to employee share-based compensation plans					(62)
Balance, end of year at Dec. 31, 2017	23,731	22,886	33,462	(343)	(32,274)
Balance, beginning of year (in shares) at Dec. 31, 2016						279.6
Common shares outstanding
Treasury stock acquired — share repurchase authorization (in shares)						(10.9)
Net shares issued under employee share-based compensation plans (in shares)						2.7
Balance, end of year (in shares) at Dec. 31, 2017						271.4
Shareholders' Equity [Roll Forward]
Reclassification of certain tax effects from adoption of updated accounting guidance				(24)
Cumulative effect of adoption of updated accounting guidance for equity financial instruments			22	(22)
Balance, beginning of year at Dec. 31, 2017	23,731	22,886	33,462	(343)	(32,274)
Shareholders' Equity [Roll Forward]
Employee share-based compensation		108
Compensation amortization under share-based plans and other changes		150
Reclassification of certain tax effects from adoption of updated accounting guidance			24	(24)
Net income	2,523		2,523
Dividends			(818)
Other			(9)
Other comprehensive income (loss)	(1,470)			(1,470)
Treasury stock acquired — share repurchase authorization					(1,270)
Net shares acquired related to employee share-based compensation plans	(51)				(51)
Balance, end of year at Dec. 31, 2018	$ 22,894	23,144	35,204	(1,859)	(33,595)
Balance, beginning of year (in shares) at Dec. 31, 2017						271.4
Common shares outstanding
Treasury stock acquired — share repurchase authorization (in shares)						(9.6)
Net shares issued under employee share-based compensation plans (in shares)						1.8
Balance, end of year (in shares) at Dec. 31, 2018	263.6					263.6
Shareholders' Equity [Roll Forward]
Cumulative effect of adoption of updated accounting guidance for equity financial instruments				(22)
Employee share-based compensation		180
Compensation amortization under share-based plans and other changes		145
Net income	$ 2,622		2,622
Dividends			(848)
Other			(1)
Other comprehensive income (loss)	2,499			2,499
Treasury stock acquired — share repurchase authorization	(1,500)				(1,500)
Net shares acquired related to employee share-based compensation plans	(48)				(48)
Balance, end of year at Dec. 31, 2019	$ 25,943	$ 23,469	$ 36,977	$ 640	$ (35,143)
Common shares outstanding
Treasury stock acquired — share repurchase authorization (in shares)	(10.8)					(10.8)
Net shares issued under employee share-based compensation plans (in shares)						2.7
Balance, end of year (in shares) at Dec. 31, 2019	255.5					255.5

Consolidated Statement of Cash

Consolidated Statement of Cash Flows - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash flows from operating activities
Net income		$ 2,622	$ 2,523	$ 2,056
Adjustments to reconcile net income to net cash provided by operating activities:
Net realized investment gains	[1]	(113)	(114)	(216)
Depreciation and amortization		763	803	813
Deferred federal income tax expense (benefit)		(33)	(13)	337
Amortization of deferred acquisition costs		4,601	4,381	4,166
Equity in income from other investments		(251)	(365)	(397)
Premiums receivable		(384)	(393)	(394)
Reinsurance recoverables		157	(100)	16
Deferred acquisition costs		(4,747)	(4,488)	(4,257)
Claims and claim adjustment expense reserves		1,047	1,246	1,460
Unearned premium reserves		1,008	710	521
Other operating activities		535	190	43
Net cash provided by operating activities		5,205	4,380	4,148
Cash flows from investing activities
Proceeds from maturities of fixed maturities		6,845	7,086	8,750
Proceeds from sales of investments:
Fixed maturities		2,187	3,546	1,854
Equity securities		140	178
Equity securities				765
Real estate investments		0	74	23
Other investments		459	511	468
Purchases of investments:
Fixed maturities		(10,711)	(13,526)	(12,250)
Equity securities		(94)	(117)
Equity securities				(459)
Real estate investments		(107)	(74)	(59)
Other investments		(497)	(537)	(541)
Net sales (purchases) of short-term securities		(957)	908	(26)
Securities transactions in the course of settlement		158	(56)	(47)
Acquisitions, net of cash acquired		0	(4)	(439)
Other investing activities		(325)	(318)	(241)
Net cash used in investing activities		(2,902)	(2,329)	(2,202)
Cash flows from financing activities
Treasury stock acquired — share repurchase authorization		(1,500)	(1,270)	(1,378)
Treasury stock acquired — net employee share-based compensation		(48)	(51)	(62)
Dividends paid to shareholders		(844)	(814)	(785)
Payment of debt		(500)	(600)	(657)
Issuance of debt		492	591	789
Issuance of common stock -- employee share options		213	132	173
Net cash used in financing activities		(2,187)	(2,012)	(1,920)
Effect of exchange rate changes on cash		5	(10)	11
Net increase in cash		121	29	37
Cash at beginning of year		373	344	307
Cash at end of year		494	373	344
Supplemental disclosure of cash flow information
Income taxes paid		428	408	514
Interest paid		$ 338	$ 347	$ 367

[1]	Total other-than-temporary impairment (OTTI) losses were $(3) million , $(1) million and $(13) million for the years ended December 31, 2019 , 2018 and 2017 , respectively. Of total OTTI, credit losses of $(4) million , $(1) million and $(14) million for the years ended December 31, 2019 , 2018 and 2017 , respectively, were recognized in net realized investment gains. In addition, unrealized gains (losses) from other changes in total OTTI of $1 million , $0 million and $1 million for the years ended December 31, 2019 , 2018 and 2017 , respectively, were recognized in other comprehensive income (loss) as part of changes in net unrealized gains (losses) on investment securities having credit losses recognized in the consolidated statement of income.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
Summary of Significant Accounting Policies	Dec. 31, 2019
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Basis of Presentation The consolidated financial statements include the accounts of The Travelers Companies, Inc. (together with its subsidiaries, the Company). The preparation of the consolidated financial statements in conformity with U.S. generally accepted accounting principles (GAAP) requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and claims and expenses during the reporting period. Actual results could differ from those estimates. All material intercompany transactions and balances have been eliminated. Adoption of Accounting Standards Financial Instruments: Recognition and Measurement of Financial Assets and Financial Liabilities In January 2016, the Financial Accounting Standards Board (FASB) issued updated guidance to address the recognition, measurement, presentation and disclosure of certain financial instruments. The updated guidance requires equity investments, except those accounted for under the equity method of accounting, that have readily determinable fair value to be measured at fair value with any changes in fair value recognized in net income. Equity securities that do not have readily determinable fair values may be measured at estimated fair value or cost less impairment, if any, adjusted for subsequent observable price changes, with changes in the carrying value recognized in net income. The updated guidance was effective for the quarter ended March 31, 2018 and early application of certain of the provisions in the updated guidance was allowed. The Company adopted the updated guidance for the quarter ended March 31, 2018 and elected to report changes in the fair value of equity investments in net realized investment gains (losses). The adoption of this guidance resulted in the recognition of $22 million of net after-tax unrealized gains on equity investments as a cumulative effect adjustment that increased retained earnings as of January 1, 2018 and decreased accumulated other comprehensive income (AOCI) by the same amount. At December 31, 2017, equity investments were classified as available-for-sale on the Company's balance sheet. However, upon adoption, the updated guidance eliminated the available-for-sale balance sheet classification for equity investments. Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income In February 2018, the FASB issued updated guidance that allows a reclassification from AOCI to retained earnings of the stranded tax effects that occurred due to the enactment of the Tax Cuts and Jobs Act of 2017 (TCJA). The updated guidance was effective for the quarter ended March 31, 2019, with early adoption allowed, and was required to be applied retrospectively to each period in which there are items impacted by the TCJA remaining in AOCI or at the beginning of the period of adoption. The Company adopted the updated guidance for the quarter ended March 31, 2019 and elected to reclassify the income tax effects of the TCJA from AOCI to retained earnings as of January 1, 2018. This reclassification resulted in an increase in retained earnings of $24 million as of January 1, 2018 and a decrease in AOCI by the same amount. Leases In February 2016, the FASB issued updated guidance on the accounting for leases that requires lessees to recognize a right-to-use asset and a lease liability for leases with terms of more than 12 months and retains the two classifications of a lease as either an operating or finance lease (previously referred to as a capital lease). The updated guidance was effective for reporting periods beginning after December 15, 2018 and required that the earliest comparative period presented include the measurement and recognition of existing leases with an adjustment to equity as if the updated guidance had always been applied. Alternatively, an entity may elect to recognize a cumulative effect adjustment to the the opening balance of retained earnings in the year of adoption. Early adoption was permitted. The Company adopted the updated guidance for leases for the quarter ended March 31, 2019 and elected to utilize a cumulative-effect adjustment to the opening balance of retained earnings for the year of adoption. Accordingly, the Company’s reporting for the comparative periods prior to adoption continue to be presented in the financial statements in accordance with previous lease accounting guidance. The Company also elected to apply all practical expedients applicable to the Company in the updated guidance for transition for leases in effect at adoption, including using hindsight to determine the lease term of existing leases, the option to not reassess whether an existing contract is a lease or contains a lease and whether the lease is an operating or finance lease. The adoption of the updated guidance resulted in the Company recognizing a right-of-use asset of $320 million as part of other assets and a lease liability of $384 million as part of other liabilities in the consolidated balance sheet, as well as de-recognizing the liability for deferred rent that was required under the previous guidance, for its corporate real estate agreements at March 31, 2019. The cumulative effect adjustment to the opening balance of retained earnings at January 1, 2019 was zero . The adoption of the updated guidance did not have a material effect on the Company’s results of operations or liquidity. Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract In August 2018, the FASB issued updated guidance on a customer's accounting for the implementation, set-up, and other upfront costs incurred in a cloud computing arrangement that is hosted by the vendor, i.e. a service contract. The updated guidance is effective for the quarter ending March 31, 2020, with early adoption permitted. The updated guidance requires an entity to determine the stage of a project that the implementation activity relates to and the nature of the associated costs in order to determine whether those costs should be expensed as incurred or capitalized. The updated guidance also requires the entity to amortize the capitalized implementation costs as an expense over the term of the hosting arrangement. The Company elected to adopt the guidance for the quarter ended March 31, 2019 and applied the guidance prospectively. The adoption of the updated guidance did not have a material effect on the Company’s results of operations, financial position or liquidity. Revenue from Contracts with Customers In May 2014, the FASB issued updated guidance to clarify the principles for recognizing revenue. The updated guidance was effective for the quarter ended March 31, 2018 and required an entity to recognize revenue as performance obligations are met, in order to reflect the transfer of goods or services to customers in an amount that reflects the consideration the entity is entitled to receive for those goods or services. For the year ended December 31, 2018 , approximately $171 million , or less than 1% of the Company's total revenues, were within the scope of this updated guidance and were generated from the services described below. While insurance contracts are not within the scope of this updated guidance, the Company’s revenue related to certain services with no underlying insurance risk is subject to the updated guidance. These services include the following: (i) insurance-related services, such as risk management services, claims administration, loss control and risk management information services on behalf of non-insureds; (ii) servicing carrier fees for various residual market pools and associations; and (iii) administrative fees related to servicing third-party insurers’ obligations to participate in the Workers' Compensation Residual Market Plans in certain states. The adoption of the updated guidance did not have a material impact on the Company's revenues. These revenues are earned as the Company completes its performance obligations, which primarily occurs on a pro rata basis over the contract service period and reported in fee income in the Company’s consolidated statement of income. Commissions earned from on-line insurance brokerage services are also subject to this updated guidance and there was not a material impact on these commissions from the adoption of the updated guidance. Commissions are generally earned upon collection of the gross premium in accordance with the contracts and an accrual is made to recognize policy cancellations, either at the policyholder’s direction or for non-payment. Commissions are reported in other revenues in the Company's consolidated statement of income. The Company does not capitalize the costs to obtain or fulfill the contracts for which revenues are reported in fee income and other revenues and has not recognized any material impairment losses on the receivables related to these contracts. The Company adopted the updated guidance for the quarter ended March 31, 2018. The adoption did not have a material effect on the Company’s results of operations, financial position or liquidity. Other Accounting Standards Not Yet Adopted Financial Instruments - Credit Losses: Measurement of Credit Losses on Financial Instruments In June 2016, the FASB issued updated guidance for the accounting for credit losses for financial instruments. The updated guidance applies a new credit loss model (current expected credit losses or CECL) for determining credit-related impairments for financial instruments measured at amortized cost (including reinsurance recoverables and structured settlements that are recorded as part of reinsurance recoverables) and requires an entity to estimate the credit losses expected over the life of an exposure or pool of exposures. The estimate of expected credit losses should consider historical information, current information, as well as reasonable and supportable forecasts, including estimates of prepayments. The expected credit losses, and subsequent adjustments to such losses, are recorded through an allowance account that is deducted from the amortized cost basis of the financial asset, with the net carrying value of the financial asset presented on the consolidated balance sheet at the amount expected to be collected. The updated guidance also amends the current other-than-temporary impairment model for available-for-sale debt securities by requiring the recognition of impairments relating to credit losses through an allowance account and limits the amount of credit loss to the difference between a security’s amortized cost basis and its fair value. In addition, the length of time a security has been in an unrealized loss position will no longer impact the determination of whether a credit loss exists. The updated guidance is effective for the quarter ending March 31, 2020. The Company expects to recognize an after-tax cumulative effect adjustment of approximately $43 million to reflect the impact of recognizing expected credit losses, as compared to incurred credit losses recognized under the previous guidance. This adjustment is primarily associated with structured settlements that are recorded as part of reinsurance recoverables. The cumulative effect adjustment will decrease retained earnings as of January 1, 2020 and increase the allowance for uncollectible reinsurance. Intangibles - Goodwill and Other In January 2017, the FASB issued updated guidance that eliminates the requirement to calculate the implied fair value of goodwill (i.e., Step 2 of the current goodwill impairment test) to measure a goodwill impairment charge. Instead, entities will record an impairment charge by comparing a reporting unit’s fair value with its carrying amount and recognizing an impairment charge for the excess of the carrying amount over estimated fair value (i.e., Step 1 of current guidance). The implied fair value of goodwill is currently determined in Step 2 by deducting the fair value of all assets and liabilities of the reporting unit (determined in the same manner as a business combination) from the reporting unit’s fair value as determined in Step 1 (including any corporate-level assets or liabilities that were included in the determination of the carrying amount and fair value of the reporting unit in Step 1). The updated guidance requires an entity to perform its annual, or interim, impairment test by either: (1) an initial qualitative assessment of factors (such as changes in management, key personnel, strategy, key technology or customers) that may impact a reporting unit’s fair value and lead to the determination that it is more likely than not that the reporting unit’s fair value is less than its carrying value, including goodwill (consistent with current guidance), or (2) applying Step 1. The updated guidance is effective for the quarter ending March 31, 2020 and is to be applied prospectively. Early adoption is permitted for interim or annual goodwill impairment tests performed on testing dates after January 1, 2017. The adoption of this guidance is not expected to have a material effect on the Company’s results of operations, financial position or liquidity. Income Taxes - Simplifying the Accounting for Income Taxes In December 2019, the FASB issued updated guidance for the accounting for income taxes. The updated guidance is intended to simplify the accounting for income taxes by removing several exceptions contained in existing guidance and amending other existing guidance to simplify several other income tax accounting matters. The updated guidance is effective for the quarter ending March 31, 2021. Early adoption is permitted. The adoption of this guidance is not expected to have a material effect on the Company’s results of operations, financial position or liquidity. Accounting Policies Investments Fixed Maturities Fixed maturities include bonds, notes and redeemable preferred stocks. Fixed maturities, including instruments subject to securities lending agreements, are classified as available for sale and reported at fair value, with unrealized investment gains and losses, net of income taxes, charged or credited directly to other comprehensive income. Equity Securities Equity securities, which include public common and non-redeemable preferred stocks, are reported at fair value with changes in fair value recognized in net income. Prior to January 1, 2018, equity securities were classified as available for sale and changes in their fair value were charged or credited directly to other comprehensive income. Real Estate Investments The Company’s real estate investments include warehouses, office buildings and other commercial land and properties that are directly owned. Real estate is recorded on the purchase date at the purchase price, which generally represents fair value, and is supported by internal analysis or external appraisals that use discounted cash flow analyses and other acceptable valuation techniques. Real estate held for investment purposes is subsequently carried at cost less accumulated depreciation. Buildings are depreciated on a straight-line basis over the shorter of the expected useful life of the building or 39 years . Real estate held for sale is carried at lower of cost or fair value, less estimated costs to sell. Short-term Securities Short-term securities have an original maturity of less than one year and are carried at amortized cost, which approximates fair value. Other Investments Investments in Private Equity Limited Partnerships, Hedge Funds and Real Estate Partnerships The Company uses the equity method of accounting for investments in private equity limited partnerships, hedge funds and real estate partnerships. The partnerships and the hedge funds generally report investments on their balance sheet at fair value. The financial statements prepared by the investee are received by the Company on a lag basis, with the lag period generally dependent upon the type of underlying investments. The private equity and real estate partnerships provide financial information quarterly which is generally available to investors, including the Company, within three months following the date of the reporting period. The hedge funds provide financial information monthly, which is generally available to investors within one month following the date of the reporting period. The Company regularly requests financial information from the partnerships prior to the receipt of the partnerships’ financial statements and records any material information obtained from these requests in its consolidated financial statements. Other Also included in other investments are non-public common equities, preferred equities and derivatives. Non-public common equities and preferred equities are reported at fair value with changes in fair value recognized in net income. Prior to January 1, 2018, non-public common equities and preferred equities were reported at fair value with changes in fair value, net of taxes, charged or credited directly to other comprehensive income. The Company’s derivative financial instruments are carried at fair value, with the changes in fair value reflected in the consolidated statement of income in net realized investment gains (losses). For a further discussion of the derivatives used by the Company, see note 3. Net Investment Income Investment income from fixed maturities is recognized based on the constant effective yield method which includes an adjustment for estimated principal pre-payments, if any. The effective yield used to determine amortization for fixed maturities subject to prepayment risk (e.g., asset-backed, loan-backed and structured securities) is recalculated and adjusted periodically based upon actual historical and/or projected future cash flows, which are obtained from a widely-accepted securities data provider. The adjustments to the yield for highly rated prepayable fixed maturities are accounted for using the retrospective method. The adjustments to the yield for non-highly rated prepayable fixed maturities are accounted for using the prospective method. Dividends on equity securities (including those with transfer restrictions) are recognized in income when declared. Rental income on real estate is recognized on a straight-line basis over the lease term. See the section titled: Real Estate in note 3 for further discussion. Investments in private equity limited partnerships, hedge funds, real estate partnerships and joint ventures are accounted for using the equity method of accounting, whereby the Company’s share of the investee’s earnings or losses in the fund is reported in net investment income. Accrual of income is suspended on non-securitized fixed maturities that are in default, or on which it is likely that future payments will not be made as scheduled. Interest income on investments in default is recognized only when payments are received. Investments included in the consolidated balance sheet that were not income-producing for the preceding 12 months were not material. For fixed maturities where the Company records an other-than-temporary impairment, a determination is made as to the cause of the impairment and whether the Company expects a recovery in the value. For fixed maturities where the Company expects a recovery in value, not necessarily to par, the constant effective yield method is utilized, and the investment is amortized to the expected recovery amount. Investment Gains and Losses Net realized investment gains and losses are included as a component of pre-tax revenues based upon specific identification of the investments sold on the trade date. Included in net realized investment gains (losses) are other-than-temporary impairment losses on invested assets other than those investments accounted for using the equity method of accounting as described in the “Investment Impairments” section that follows. Investment Impairments The Company conducts a periodic review to identify and evaluate invested assets having other-than-temporary impairments. Other-Than-Temporary Impairments of Fixed Maturities Some of the factors considered in identifying other-than-temporary impairments of fixed maturities include: (1) the extent to which the fair value has been less than amortized cost; (2) the financial condition, near-term and long-term prospects for the issuer, including the relevant industry conditions and trends, and implications of rating agency actions and offering prices; (3) the likelihood of the recoverability of principal and interest; (4) whether it is more likely than not that the Company will be required to sell the investment prior to an anticipated recovery in value; and (5) the length of time and extent to which the fair value has been less than amortized cost. For fixed maturity investments that the Company does not intend to sell or for which it is more likely than not that the Company would not be required to sell before an anticipated recovery in value, the Company separates the credit loss component of the impairment from the amount related to all other factors and reports the credit loss component in net realized investment gains (losses). The impairment related to all other factors is reported in other comprehensive income. For fixed maturity investments the Company intends to sell or for which it is more likely than not that the Company will be required to sell before an anticipated recovery in value, the full amount of the impairment is included in net realized investment gains (losses). Upon recognizing an other-than-temporary impairment, the new cost basis of the investment is the previous amortized cost basis less the other-than-temporary impairment recognized in net realized investment gains (losses). The new cost basis is not adjusted for any subsequent recoveries in fair value; however, for fixed maturity investments the difference between the new cost basis and the expected cash flows is accreted on a quarterly basis to net investment income over the remaining expected life of the investment. Determination of Credit Loss — Fixed Maturities The Company determines the credit loss component of fixed maturity investments by utilizing discounted cash flow modeling to determine the present value of the security and comparing the present value with the amortized cost of the security. If the amortized cost is greater than the present value of the expected cash flows, the difference is considered a credit loss and recognized in net realized investment gains (losses). For non-structured fixed maturities (U.S. Treasury securities, obligations of U.S. government and government agencies and authorities, obligations of states, municipalities and political subdivisions, debt securities issued by foreign governments and certain corporate debt), the estimate of expected cash flows is determined by projecting a recovery value and a recovery time frame and assessing whether further principal and interest will be received. The determination of recovery value incorporates an issuer valuation assumption utilizing one or a combination of valuation methods as deemed appropriate by the Company. The Company determines the undiscounted recovery value by allocating the estimated value of the issuer to the Company’s assessment of the priority of claims. The present value of the cash flows is determined by applying the effective yield of the security at the date of acquisition (or the most recent implied rate used to accrete the security if the implied rate has changed as a result of a previous impairment) and an estimated recovery time frame. Generally, that time frame for securities for which the issuer is in bankruptcy is 12 months . For securities for which the issuer is financially troubled but not in bankruptcy, that time frame is generally 24 months . Included in the present value calculation are expected principal and interest payments; however, for securities for which the issuer is classified as bankrupt or in default, the present value calculation assumes no interest payments and a single recovery amount. In estimating the recovery value, significant judgment is involved in the development of assumptions relating to a myriad of factors related to the issuer including, but not limited to, revenue, margin and earnings projections, the likely market or liquidation values of assets, potential additional debt to be incurred pre- or post-bankruptcy/restructuring, the ability to shift existing or new debt to different priority layers, the amount of restructuring/bankruptcy expenses, the size and priority of unfunded pension obligations, litigation or other contingent claims, the treatment of intercompany claims and the likely outcome with respect to inter-creditor conflicts. For structured fixed maturity securities (primarily residential and commercial mortgage-backed securities and asset-backed securities), the Company estimates the present value of the security by projecting future cash flows of the assets underlying the securitization, allocating the flows to the various tranches based on the structure of the securitization and determining the present value of the cash flows using the effective yield of the security at the date of acquisition (or the most recent implied rate used to accrete the security if the implied rate has changed as a result of a previous impairment or changes in expected cash flows). The Company incorporates levels of delinquencies, defaults and severities as well as credit attributes of the remaining assets in the securitization, along with other economic data, to arrive at its estimate of the parameters applied to the assets underlying the securitization. Real Estate Investments On at least an annual basis, the Company obtains independent appraisals for substantially all of its real estate investments. In addition, the carrying value of all real estate investments is reviewed for impairment on a quarterly basis or when events or changes in circumstances indicate that the carrying amount may not be recoverable. The review for impairment considers the valuation from the independent appraisal, when applicable, and incorporates an estimate of the undiscounted cash flows expected to result from the use and eventual disposition of the real estate property. An impairment loss is recognized if the expected future undiscounted cash flows are less than the carrying value of the real estate property. The impairment loss is the amount by which the carrying amount exceeds fair value. Other Investments The Company reviews its investments in private equity limited partnerships, hedge funds and real estate partnerships for impairment no less frequently than quarterly and monitors the performance throughout the year through discussions with the managers/general partners. If the Company becomes aware of an impairment of a partnership’s investments at the balance sheet date prior to receiving the partnership’s financial statements, it will recognize an impairment by recording a reduction in the carrying value of the partnership with a corresponding charge to net investment income. Changes in Intent to Sell Temporarily Impaired Assets The Company may, from time to time, sell invested assets subsequent to the balance sheet date that it did not intend to sell at the balance sheet date. Conversely, the Company may not sell invested assets that it asserted that it intended to sell at the balance sheet date. Such changes in intent are due to events occurring subsequent to the balance sheet date. The types of events that may result in a change in intent include, but are not limited to, significant changes in the economic facts and circumstances related to the invested asset (e.g., a downgrade or upgrade from a rating agency), significant unforeseen changes in liquidity needs, or changes in tax laws or the regulatory environment. Securities Lending The Company has, from time to time, engaged in securities lending activities from which it generates net investment income by lending certain of its investments to other institutions for short periods of time. Borrowers of these securities provide collateral equal to at least 102% of the market value of the loaned securities plus accrued interest. This collateral is held by a third-party custodian, and the Company has the right to access the collateral only in the event that the institution borrowing the Company’s securities is in default under the lending agreement (i.e., the Company is not permitted to re-pledge or sell any such collateral). Therefore, the Company does not recognize the receipt of the collateral held by the third-party custodian or the obligation to return the collateral. The loaned securities remain a recorded asset of the Company. The Company accepts only cash as collateral for securities on loan and restricts the manner in which that cash is invested. Reinsurance Recoverables Amounts recoverable from reinsurers are estimated in a manner consistent with the associated claim liability. The Company reports its reinsurance recoverables net of an allowance for estimated uncollectible reinsurance recoverables. The allowance is based upon the Company’s ongoing review of amounts outstanding, length of collection periods, changes in reinsurer credit standing, disputes, applicable coverage defenses and other relevant factors. Amounts deemed to be uncollectible, including amounts due from known insolvent reinsurers, are written off against the allowance for estimated uncollectible reinsurance recoverables. Any subsequent collections of amounts previously written off are reported as part of claims and claim adjustment expenses. The Company evaluates and monitors the financial condition of its reinsurers under voluntary reinsurance arrangements to minimize its exposure to significant losses from reinsurer insolvencies. Deferred Acquisition Costs Incremental direct costs of acquired, new and renewal insurance contracts, consisting of commissions (other than contingent commissions) and premium-related taxes, are capitalized and charged to expense pro rata over the contract periods in which the related premiums are earned. Deferred acquisition costs are reviewed to determine if they are recoverable from future income and, if not, are charged to expense. Future investment income attributable to related premiums is taken into account in measuring the recoverability of the carrying value of this asset. All other acquisition expenses are charged to operations as incurred. Contractholder Receivables and Payables Under certain workers’ compensation insurance contracts with deductible features, the Company is obligated to pay the claimant for the full amount of the claim. The Company is subsequently reimbursed by the policyholder for the deductible amount. These amounts are included on a gross basis in the consolidated balance sheet in contractholder payables and contractholder receivables, respectively. Goodwill and Other Intangible Assets The Company performs a review, on at least an annual basis, of goodwill held by the reporting units which are the Company’s three operating and reportable segments: Business Insurance; Bond & Specialty Insurance; and Personal Insurance. The Company estimates the fair value of its reporting units and compares it to their carrying value, including goodwill. If the carrying values of the reporting units were to exceed their fair value, the amount of the impairment would be calculated and goodwill adjusted accordingly. The Company uses a discounted cash flow model to estimate the fair value of its reporting units. The discounted cash flow model is an income approach to valuation that is based on a detailed cash flow analysis for deriving a current fair value of reporting units and is representative of the Company’s reporting units’ current and expected future financial performance. The discount rate assumptions reflect the Company’s assessment of the risks inherent in the projected future cash flows and the Company’s weighted-average cost of capital, and are compared against available market data for reasonableness. Other indefinite-lived intangible assets held by the Company are also reviewed for impairment on at least an annual basis. The classification of the asset as indefinite-lived is reassessed and an impairment is recognized if the carrying amount of the asset exceeds its fair value. Intangible assets that are deemed to have a finite useful life are amortized over their useful lives

Segment Information

Segment Information	12 Months Ended
Segment Information	Dec. 31, 2019
Segment Reporting [Abstract]
Segment Information	SEGMENT INFORMATION The accounting policies used to prepare the segment reporting data for the Company’s three reportable business segments are the same as those described in the Summary of Significant Accounting Policies in note 1. Except as described below for certain legal entities, the Company allocates its invested assets and the related net investment income to its reportable business segments. Pre-tax net investment income is allocated based upon an investable funds concept, which takes into account liabilities (net of non-invested assets) and appropriate capital considerations for each segment. For investable funds, a benchmark investment yield is developed that reflects the estimated duration of the loss reserves’ future cash flows, the interest rate environment at the time the losses were incurred and A+ rated corporate debt instrument yields. For capital, a benchmark investment yield is developed that reflects the average yield on the total investment portfolio. The benchmark investment yields are applied to each segment’s investable funds and capital, respectively, to produce a total notional investment income by segment. The Company’s actual net investment income is allocated to each segment in proportion to the respective segment’s notional investment income to total notional investment income. There are certain legal entities within the Company that are dedicated to specific reportable business segments. The invested assets and related net investment income from these legal entities are reported in the applicable business segment and are not allocated among the other business segments. The cost of the Company’s catastrophe treaty program is included in the Company’s ceded premiums and is allocated among reportable business segments based on an estimate of actual market reinsurance pricing using expected losses calculated by the Company’s catastrophe model, adjusted for any experience adjustments. The following tables summarize the components of the Company’s revenues, income, net written premiums and total assets by reportable business segments. (for the year ended December 31, in millions) Business Insurance Bond & Specialty Insurance Personal Insurance Total Reportable Segments 2019 Premiums $ 15,300 $ 2,565 $ 10,407 $ 28,272 Net investment income 1,816 233 419 2,468 Fee income 437 — 22 459 Other revenues 155 26 87 268 Total segment revenues (1) $ 17,708 $ 2,824 $ 10,935 $ 31,467 Amortization and depreciation $ 3,037 $ 533 $ 1,787 $ 5,357 Income tax expense 223 151 195 569 Segment income (1) 1,392 618 824 2,834 2018 Premiums $ 14,722 $ 2,420 $ 9,917 $ 27,059 Net investment income 1,833 233 408 2,474 Fee income 412 — 20 432 Other revenues 112 23 66 201 Total segment revenues (1) $ 17,079 $ 2,676 $ 10,411 $ 30,166 Amortization and depreciation $ 2,943 $ 515 $ 1,719 $ 5,177 Income tax expense 259 198 42 499 Segment income (1) 1,638 793 297 2,728 2017 Premiums $ 14,146 $ 2,307 $ 9,230 $ 25,683 Net investment income 1,786 228 383 2,397 Fee income 430 — 17 447 Other revenues 69 24 60 153 Total segment revenues (1) $ 16,431 $ 2,559 $ 9,690 $ 28,680 Amortization and depreciation $ 2,852 $ 493 $ 1,627 $ 4,972 Income tax expense (benefit) 448 208 (44 ) 612 Segment income (1) 1,613 556 128 2,297 _________________________________________ (1) Segment revenues for reportable business segments exclude net realized investment gains. Segment income for reportable business segments equals net income excluding the after-tax impact of net realized investment gains and, in 2017, the impact of the Tax Cuts and Jobs Act of 2017 at enactment. Net written premiums by market were as follows: (for the year ended December 31, in millions) 2019 2018 2017 Business Insurance: Domestic: Select Accounts $ 2,911 $ 2,828 $ 2,800 Middle Market 8,630 8,214 7,756 National Accounts 1,051 1,025 1,010 National Property and Other 1,965 1,805 1,691 Total Domestic 14,557 13,872 13,257 International 1,072 1,084 1,013 Total Business Insurance 15,629 14,956 14,270 Bond & Specialty Insurance: Domestic: Management Liability 1,605 1,455 1,367 Surety 866 835 793 Total Domestic 2,471 2,290 2,160 International 268 238 199 Total Bond & Specialty Insurance 2,739 2,528 2,359 Personal Insurance: Domestic: Agency: Automobile 5,124 4,972 4,646 Homeowners and Other 4,540 4,148 3,933 Total Agency 9,664 9,120 8,579 Direct-to-Consumer 412 396 361 Total Domestic 10,076 9,516 8,940 International 707 708 650 Total Personal Insurance 10,783 10,224 9,590 Total consolidated net written premiums $ 29,151 $ 27,708 $ 26,219 Business Segment Reconciliations (for the year ended December 31, in millions) 2019 2018 2017 Revenue reconciliation Earned premiums Business Insurance: Domestic: Workers’ compensation $ 3,829 $ 3,899 $ 3,962 Commercial automobile 2,632 2,388 2,132 Commercial property 1,937 1,828 1,775 General liability 2,342 2,181 2,047 Commercial multi-peril 3,453 3,333 3,198 Other 40 28 29 Total Domestic 14,233 13,657 13,143 International 1,067 1,065 1,003 Total Business Insurance 15,300 14,722 14,146 Bond & Specialty Insurance: Domestic: Fidelity and surety 1,036 1,017 977 General liability 1,082 1,004 962 Other 216 195 187 Total Domestic 2,334 2,216 2,126 International 231 204 181 Total Bond & Specialty Insurance 2,565 2,420 2,307 Personal Insurance: Domestic Automobile 5,311 5,097 4,655 Homeowners and Other 4,393 4,135 3,943 Total Domestic 9,704 9,232 8,598 International 703 685 632 Total Personal Insurance 10,407 9,917 9,230 Total earned premiums 28,272 27,059 25,683 Net investment income 2,468 2,474 2,397 Fee income 459 432 447 Other revenues 268 201 153 Total segment revenues 31,467 30,166 28,680 Other revenues 1 2 6 Net realized investment gains 113 114 216 Total revenues $ 31,581 $ 30,282 $ 28,902 Income reconciliation, net of tax Total segment income $ 2,834 $ 2,728 $ 2,297 Interest Expense and Other (1) (297 ) (298 ) (254 ) Core income 2,537 2,430 2,043 Net realized investment gains 85 93 142 Impact of Tax Cuts and Jobs Act of 2017 at enactment — — (129 ) Net income $ 2,622 $ 2,523 $ 2,056 ________________________________________ (1) The primary component of Interest Expense and Other was after-tax interest expense of $272 million , $278 million and $240 million in 2019 , 2018 and 2017 , respectively. (at December 31, in millions) 2019 2018 Asset reconciliation: Business Insurance $ 83,896 $ 78,965 Bond & Specialty Insurance 8,599 8,693 Personal Insurance 17,015 15,943 Total assets for reportable segments 109,510 103,601 Other assets (1) 612 632 Total consolidated assets $ 110,122 $ 104,233 ___________________________________________ (1) The primary components of other assets at both December 31, 2019 and 2018, were accrued over-funded benefit plan assets related to the Company's qualified domestic pension plan and other intangible assets. Enterprise-Wide Disclosures The Company does not have revenue from transactions with a single customer amounting to 10 percent or more of its revenues. The following table presents revenues of the Company’s operations based on location: (for the year ended December 31, in millions) 2019 2018 2017 U.S. $ 29,638 $ 28,418 $ 27,253 Non-U.S.: Canada 1,371 1,293 1,232 Other Non-U.S. 572 571 417 Total Non-U.S. 1,943 1,864 1,649 Total revenues $ 31,581 $ 30,282 $ 28,902

Investments

Investments	12 Months Ended
Investments	Dec. 31, 2019
Investments [Abstract]
Investments	INVESTMENTS Fixed Maturities The amortized cost and fair value of investments in fixed maturities classified as available for sale were as follows: Amortized Gross Unrealized Fair (at December 31, 2019, in millions) Cost Gains Losses Value U.S. Treasury securities and obligations of U.S. government and government agencies and authorities $ 2,076 $ 19 $ — $ 2,095 Obligations of states, municipalities and political subdivisions: Local general obligation 15,490 829 4 16,315 Revenue 9,731 586 2 10,315 State general obligation 1,167 64 — 1,231 Pre-refunded 1,968 88 — 2,056 Total obligations of states, municipalities and political subdivisions 28,356 1,567 6 29,917 Debt securities issued by foreign governments 1,167 8 2 1,173 Mortgage-backed securities, collateralized mortgage obligations and pass-through securities 3,192 91 3 3,280 All other corporate bonds 30,442 1,195 18 31,619 Redeemable preferred stock 48 2 — 50 Total $ 65,281 $ 2,882 $ 29 $ 68,134 Amortized Gross Unrealized Fair (at December 31, 2018, in millions) Cost Gains Losses Value U.S. Treasury securities and obligations of U.S. government and government agencies and authorities $ 2,076 $ 4 $ 16 $ 2,064 Obligations of states, municipalities and political subdivisions: Local general obligation 14,473 219 120 14,572 Revenue 9,755 172 74 9,853 State general obligation 1,329 18 13 1,334 Pre-refunded 2,772 80 — 2,852 Total obligations of states, municipalities and political subdivisions 28,329 489 207 28,611 Debt securities issued by foreign governments 1,255 7 5 1,257 Mortgage-backed securities, collateralized mortgage obligations and pass-through securities 2,557 54 38 2,573 All other corporate bonds 29,307 156 583 28,880 Redeemable preferred stock 77 2 — 79 Total $ 63,601 $ 712 $ 849 $ 63,464 The amortized cost and fair value of fixed maturities by contractual maturity follow. Actual maturities will differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without call or prepayment penalties. (at December 31, 2019, in millions) Amortized Cost Fair Value Due in one year or less $ 3,738 $ 3,760 Due after 1 year through 5 years 17,729 18,241 Due after 5 years through 10 years 17,262 18,215 Due after 10 years 23,360 24,638 62,089 64,854 Mortgage-backed securities, collateralized mortgage obligations and pass-through securities 3,192 3,280 Total $ 65,281 $ 68,134 Pre-refunded bonds of $2.06 billion and $2.85 billion at December 31, 2019 and 2018 , respectively, were bonds for which states or municipalities have established irrevocable trusts, almost exclusively comprised of U.S. Treasury securities and obligations of U.S. government and government agencies and authorities. These trusts were created to fund the payment of principal and interest due under the bonds. The Company’s fixed maturity investment portfolio at December 31, 2019 and 2018 included $3.28 billion and $2.57 billion , respectively, of residential mortgage-backed securities, which include pass-through securities and collateralized mortgage obligations (CMOs). Included in the totals at December 31, 2019 and 2018 were $1.52 billion and $859 million , respectively, of GNMA, FNMA, FHLMC (excluding FHA project loans) and Canadian government guaranteed residential mortgage-backed pass-through securities classified as available for sale. Also included in those totals were residential CMOs classified as available for sale with a fair value of $1.76 billion and $1.71 billion at December 31, 2019 and 2018 , respectively. Approximately 54% and 52% of the Company’s CMO holdings at December 31, 2019 and 2018 , respectively, were guaranteed by or fully collateralized by securities issued by GNMA, FNMA or FHLMC. The weighted average credit rating of the $816 million and $828 million of non-guaranteed CMO holdings at December 31, 2019 and 2018 , respectively, was “Aaa/Aa1” and “Aa1,” respectively. The weighted average credit rating of all of the above securities was Aaa/Aa1” at both December 31, 2019 and 2018 . At December 31, 2019 and 2018 , the Company held commercial mortgage-backed securities (CMBS, including FHA project loans) of $1.51 billion and $1.22 billion , respectively, which are included in “All other corporate bonds” in the tables above. At December 31, 2019 and 2018 , approximately $559 million and $458 million of these securities, respectively, or the loans backing such securities, contained guarantees by the U.S. government or a government-sponsored enterprise. The weighted average credit rating of the $950 million and $759 million of non-guaranteed securities at December 31, 2019 and 2018 , respectively, was “Aaa” at both dates. The CMBS portfolio is supported by loans that are diversified across economic sectors and geographical areas. The weighted average credit rating of the CMBS portfolio was “Aaa” at both December 31, 2019 and 2018 . At December 31, 2019 and 2018 , the Company had $404 million and $367 million , respectively, of securities on loan as part of a tri-party lending agreement. Proceeds from sales of fixed maturities classified as available for sale were $2.19 billion , $3.55 billion and $1.85 billion in 2019 , 2018 and 2017 , respectively. Gross gains of $67 million , $51 million and $42 million and gross losses of $8 million , $18 million and $38 million were realized on those sales in 2019 , 2018 and 2017 , respectively. At December 31, 2019 and 2018 , the Company’s insurance subsidiaries had $4.34 billion and $4.23 billion , respectively, of securities on deposit at financial institutions in certain states pursuant to the respective states’ insurance regulatory requirements. Funds deposited with third parties to be used as collateral to secure various liabilities on behalf of insureds, cedants and other creditors had a fair value of $54 million and $37 million at December 31, 2019 and 2018 , respectively. Other investments pledged as collateral securing outstanding letters of credit had a fair value of $1 million at both December 31, 2019 and 2018 . In addition, the Company utilizes Lloyd’s trust deposits, whereby owned securities with a fair value of approximately $173 million and $115 million held by a wholly-owned subsidiary at December 31, 2019 and 2018 , respectively, and $34 million and $33 million held by TRV at December 31, 2019 and 2018 , respectively, were pledged into Lloyd’s trust accounts to provide a portion of the capital needed to support the Company’s obligations at Lloyd’s. Equity Securities The cost and fair value of investments in equity securities were as follows: (at December 31, 2019, in millions) Cost Gross Gains Gross Losses Fair Value Public common stock $ 341 $ 45 $ 3 $ 383 Non-redeemable preferred stock 35 7 — 42 Total $ 376 $ 52 $ 3 $ 425 (at December 31, 2018, in millions) Cost Gross Gains Gross Losses Fair Value Public common stock $ 338 $ 2 $ 24 $ 316 Non-redeemable preferred stock 44 8 — 52 Total $ 382 $ 10 $ 24 $ 368 The Company recognized $61 million and ($29) million of net gains (losses) on equity securities still held as of December 31, 2019 and 2018, respectively. Proceeds from sales of equity securities previously classified as available for sale were $765 million in 2017 . Gross gains of $239 million and gross losses of $3 million were realized on those sales in 2017 . Real Estate The Company’s real estate investments include warehouses, office buildings and other commercial land and properties that are directly owned. The Company negotiates commercial leases with individual tenants through unrelated, licensed real estate brokers. Negotiated terms and conditions include, among others, rental rates, length of lease period and improvements to the premises to be provided by the landlord. There were no sales of real estate investments in 2019 . Proceeds from the sale of real estate investments were $74 million and $23 million in 2018 and 2017 , respectively. Gross gains of $23 million and $10 million were realized on those sales in 2018 and 2017 , respectively, and there were no gross losses. Accumulated depreciation on real estate held for investment purposes was $422 million and $383 million at December 31, 2019 and 2018 , respectively. Future minimum rental income on operating leases relating to the Company’s real estate properties is expected to be $110 million , $102 million , $85 million , $61 million and $45 million for 2020 , 2021 , 2022 , 2023 and 2024 , respectively, and $71 million for 2025 and thereafter. Short-term Securities The Company’s short-term securities consist of Aaa-rated registered money market funds, U.S. Treasury securities, high-quality commercial paper (primarily A1/P1) and high-quality corporate securities purchased within a year to their maturity with a combined average of 54 days to maturity at December 31, 2019 . The amortized cost of these securities, which totaled $4.94 billion and $3.99 billion at December 31, 2019 and 2018 , respectively, approximated their fair value. Variable Interest Entities Entities which do not have sufficient equity at risk to allow the entity to finance its activities without additional financial support or in which the equity investors, as a group, do not have the characteristic of a controlling financial interest are referred to as variable interest entities (VIE). A VIE is consolidated by the variable interest holder that is determined to have the controlling financial interest (primary beneficiary) as a result of having both the power to direct the activities of a VIE that most significantly impact the VIE’s economic performance and the obligation to absorb losses or right to receive benefits from the VIE that could potentially be significant to the VIE. The Company determines whether it is the primary beneficiary of an entity subject to consolidation based on a qualitative assessment of the VIE’s capital structure, contractual terms, nature of the VIE’s operations and purpose and the Company’s relative exposure to the related risks of the VIE on the date it becomes initially involved in the VIE. The Company reassesses its VIE determination with respect to an entity on an ongoing basis. The Company is a passive investor in limited partner equity interests issued by third party VIEs. These include certain of the Company’s investments in private equity limited partnerships, hedge funds and real estate partnerships where the Company is not related to the general partner. These investments are generally accounted for under the equity method and reported in the Company’s consolidated balance sheet as other investments unless the Company is deemed the primary beneficiary. These equity interests generally cannot be redeemed. Distributions from these investments are received by the Company as a result of liquidation of the underlying investments of the funds and/or as income distribution. The Company’s maximum exposure to loss with respect to these investments is limited to the investment carrying amounts reported in the Company’s consolidated balance sheet and any unfunded commitment. The Company considers an investment in a VIE in which it has a 20% or greater equity interest as a significant VIE. Neither the Company’s carrying amounts nor the unfunded commitments related to these significant VIE’s are material individually or in the aggregate. Unrealized Investment Losses The following tables summarize, for all investments in an unrealized loss position at December 31, 2019 and 2018 , the aggregate fair value and gross unrealized loss by length of time those securities have been continuously in an unrealized loss position. The fair value amounts reported in the tables are estimates that are prepared using the process described in note 4. The Company also relies upon estimates of several factors in its review and evaluation of individual investments, using the process described in note 1, in determining whether such investments are other-than-temporarily impaired. Less than 12 months 12 months or longer Total (at December 31, 2019, in millions) Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses Fixed maturities U.S. Treasury securities and obligations of U.S. government and government agencies and authorities $ 5 $ — $ 193 $ — $ 198 $ — Obligations of states, municipalities and political subdivisions 668 6 12 — 680 6 Debt securities issued by foreign governments 257 1 147 1 404 2 Mortgage-backed securities, collateralized mortgage obligations and pass-through securities 399 2 131 1 530 3 All other corporate bonds 1,571 10 662 8 2,233 18 Total fixed maturities $ 2,900 $ 19 $ 1,145 $ 10 $ 4,045 $ 29 Less than 12 months 12 months or longer Total (at December 31, 2018, in millions) Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses Fixed maturities U.S. Treasury securities and obligations of U.S. government and government agencies and authorities $ 484 $ 5 $ 1,011 $ 11 $ 1,495 $ 16 Obligations of states, municipalities and political subdivisions 5,241 82 3,298 125 8,539 207 Debt securities issued by foreign governments 96 — 328 5 424 5 Mortgage-backed securities, collateralized mortgage obligations and pass-through securities 593 9 1,070 29 1,663 38 All other corporate bonds 12,622 303 6,872 280 19,494 583 Total fixed maturities $ 19,036 $ 399 $ 12,579 $ 450 $ 31,615 $ 849 At December 31, 2019 , the Company had no fixed maturity investments reported at fair value for which fair value was less than 80% of amortized cost. Impairment Charges Impairment charges included in net realized investment gains in the consolidated statement of income were as follows: (for the year ended December 31, in millions) 2019 2018 2017 Fixed maturities U.S. Treasury securities and obligations of U.S. government and government agencies and authorities $ — $ — $ — Obligations of states, municipalities and political subdivisions — — — Debt securities issued by foreign governments — — — Mortgage-backed securities, collateralized mortgage obligations and pass-through securities — — — All other corporate bonds 4 1 4 Redeemable preferred stock — — — Total fixed maturities 4 1 4 Equity securities Public common stock — — 9 Non-redeemable preferred stock — — — Total equity securities — — 9 Other investments — — 1 Total $ 4 $ 1 $ 14 The following tables present the cumulative amount of, and the changes during the year in, credit losses on fixed maturities held at December 31, 2019 and 2018 , that were recognized in the consolidated statement of income from other-than-temporary impairments (OTTI) and for which a portion of the OTTI was recognized in other comprehensive income (loss) in the consolidated balance sheet. Year ended December 31, 2019 (in millions) Cumulative OTTI Credit Losses Recognized for Securities Held, Beginning of Period Additions for OTTI Securities Where No Credit Losses Were Previously Recognized Additions for OTTI Securities Where Credit Losses Have Been Previously Recognized Reductions Due to Sales/Defaults of Credit- Impaired Securities Adjustments to Book Value of Credit- Impaired Securities due to Changes in Cash Flows Cumulative OTTI Credit Losses Recognized for Securities Still Held, End of Period Fixed maturities Mortgage-backed securities, collateralized mortgage obligations and pass-through securities $ 15 $ — $ — $ (9 ) $ 3 $ 9 All other corporate bonds 42 — — (49 ) 10 3 Total fixed maturities $ 57 $ — $ — $ (58 ) $ 13 $ 12 Year ended December 31, 2018 (in millions) Cumulative OTTI Credit Losses Recognized for Securities Held, Beginning of Period Additions for OTTI Securities Where No Credit Losses Were Previously Recognized Additions for OTTI Securities Where Credit Losses Have Been Previously Recognized Reductions Due to Sales/Defaults of Credit- Impaired Securities Adjustments to Book Value of Credit- Impaired Securities due to Changes in Cash Flows Cumulative OTTI Credit Losses Recognized for Securities Still Held, End of Period Fixed maturities Mortgage-backed securities, collateralized mortgage obligations and pass-through securities $ 29 $ — $ — $ (18 ) $ 4 $ 15 All other corporate bonds 46 — — (12 ) 8 42 Total fixed maturities $ 75 $ — $ — $ (30 ) $ 12 $ 57 Concentrations and Credit Quality Concentrations of credit risk arise from exposure to counterparties that are engaged in similar activities and have similar economic characteristics that could cause their ability to meet contractual obligations to be similarly affected by changes in economic or other conditions. The Company seeks to mitigate credit risk by actively monitoring the creditworthiness of counterparties, obtaining collateral as deemed appropriate and applying controls that include credit approvals, limits of credit exposure and other monitoring procedures. At December 31, 2019 and 2018 , other than U.S. Treasury securities and obligations of U.S. government and government agencies and authorities, the Company was not exposed to any concentration of credit risk of a single issuer greater than 5% of the Company’s shareholders’ equity. Included in fixed maturities are below investment grade securities totaling $1.46 billion and $1.48 billion at December 31, 2019 and 2018 , respectively. The Company defines its below investment grade securities as those securities rated below investment grade by external rating agencies, or the equivalent by the Company when a public rating does not exist. Such securities include below investment grade bonds that are publicly traded and certain other privately issued bonds that are classified as below investment grade loans. Net Investment Income (for the year ended December 31, in millions) 2019 2018 2017 Gross investment income Fixed maturities $ 2,070 $ 1,980 $ 1,895 Equity securities 15 16 28 Short-term securities 105 92 62 Real estate investments 55 48 44 Other investments 263 377 406 Gross investment income 2,508 2,513 2,435 Investment expenses 40 39 38 Net investment income $ 2,468 $ 2,474 $ 2,397 Changes in net unrealized gains (losses) on investment securities that are included as a separate component of other comprehensive income (loss) were as follows: (at and for the year ended December 31, in millions) 2019 2018 2017 Changes in net unrealized investment gains (losses) Fixed maturities $ 2,990 $ (1,515 ) $ 513 Equity securities — — (215 ) Other investments — (1 ) 4 Change in net pre-tax unrealized gains (losses) on investment securities 2,990 (1,516 ) 302 Related tax expense (benefit) 631 (319 ) 78 Change in net unrealized gains (losses) on investment securities 2,359 (1,197 ) 224 Cumulative effect of adoption of updated accounting guidance for equity financial instruments at January 1, 2018 — (22 ) — Reclassification of certain tax effects from accumulated other comprehensive income at January 1, 2018 — 152 — Balance, beginning of year (113 ) 954 730 Balance, end of year $ 2,246 $ (113 ) $ 954 The total impact of net unrealized gains on investment securities was $1.11 billion after-tax at December 31, 2017, which included the $954 million reported in accumulated other comprehensive income shown above, as well as $158 million included in retained earnings that was part of the impact of enactment of the Tax Cuts and Jobs Act of 2017 recorded in earnings. Derivative Financial Instruments From time to time, the Company enters into U.S. Treasury note futures contracts to modify the effective duration of specific assets within the investment portfolio. U.S. Treasury futures contracts require a daily mark-to-market and settlement with the broker. At December 31, 2019 and 2018 , the Company had no open U.S. Treasury futures contracts. Net realized investment gains and losses related to U.S. Treasury futures contracts in 2019 , 2018 and 2017 were not significant. The Company has a put/call option that was entered into in connection with a business acquisition that allows the Company to acquire the remaining shares of the acquired company at a future date. Net realized investment gains and losses related to this put/call option in 2019 and 2018 were not significant. The Company also sells a small amount of U.S. equity index put option contracts that are settled for cash upon their expiration or when they are rolled over. Net realized investment losses related to these derivatives in 2019 , 2018 and 2017 were not significant.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
Fair Value Measurements	Dec. 31, 2019
Fair Value Disclosures [Abstract]
Fair Value Measurements	FAIR VALUE MEASUREMENTS The Company’s estimates of fair value for financial assets and financial liabilities are based on the framework established in the fair value accounting guidance. The framework is based on the inputs used in valuation, gives the highest priority to quoted prices in active markets and requires that observable inputs be used in the valuations when available. The disclosure of fair value estimates in the fair value accounting guidance hierarchy is based on whether the significant inputs into the valuation are observable. In determining the level of the hierarchy in which the estimate is disclosed, the highest priority is given to unadjusted quoted prices in active markets and the lowest priority to unobservable inputs that reflect the Company’s significant market assumptions. The level in the fair value hierarchy within which the fair value measurement is reported is based on the lowest level input that is significant to the measurement in its entirety. The three levels of the hierarchy are as follows: • Level 1 - Unadjusted quoted market prices for identical assets or liabilities in active markets that the Company has the ability to access. • Level 2 - Quoted prices for similar assets or liabilities in active markets; quoted prices for identical or similar assets or liabilities in inactive markets; or valuations based on models where the significant inputs are observable (e.g., interest rates, yield curves, prepayment speeds, default rates, loss severities, etc.) or can be corroborated by observable market data. • Level 3 - Valuations based on models where significant inputs are not observable. The unobservable inputs reflect the Company’s own assumptions about the inputs that market participants would use. Valuation of Investments Reported at Fair Value in Financial Statements The fair value of a financial instrument is the estimated amount at which the instrument could be exchanged in an orderly transaction between knowledgeable, unrelated, willing parties, i.e., not in a forced transaction. The estimated fair value of a financial instrument may differ from the amount that could be realized if the security was sold in an immediate sale, e.g., a forced transaction. Additionally, the valuation of investments is more subjective when markets are less liquid due to the lack of market based inputs, which may increase the potential that the estimated fair value of an investment is not reflective of the price at which an actual transaction would occur. For investments that have quoted market prices in active markets, the Company uses the unadjusted quoted market prices as fair value and includes these prices in the amounts disclosed in Level 1 of the hierarchy. The Company receives the quoted market prices from third party, nationally recognized pricing services. When quoted market prices are unavailable, the Company utilizes these pricing services to determine an estimate of fair value. The fair value estimates provided from these pricing services are included in the amount disclosed in Level 2 of the hierarchy. If quoted market prices and an estimate from a pricing service are unavailable, the Company produces an estimate of fair value based on internally developed valuation techniques, which, depending on the level of observable market inputs, will render the fair value estimate as Level 2 or Level 3. The Company bases all of its estimates of fair value for assets on the bid price as it represents what a third-party market participant would be willing to pay in an arm’s length transaction. Fixed Maturities The Company utilized a pricing service to estimate fair value measurements for approximately 99% of its fixed maturities at both December 31, 2019 and 2018 . The pricing service utilizes market quotations for fixed maturity securities that have quoted prices in active markets. Since fixed maturities other than U.S. Treasury securities generally do not trade on a daily basis, the pricing service prepares estimates of fair value measurements for these securities using its proprietary pricing applications, which include available relevant market information, benchmark curves, benchmarking of like securities, sector groupings and matrix pricing. Additionally, the pricing service uses an Option Adjusted Spread model to develop prepayment and interest rate scenarios. The pricing service evaluates each asset class based on relevant market information, relevant credit information, perceived market movements and sector news. The market inputs utilized in the pricing evaluation, listed in the approximate order of priority, include: benchmark yields, reported trades, broker/dealer quotes, issuer spreads, two-sided markets, benchmark securities, bids, offers, reference data, and industry and economic events. The extent of the use of each market input depends on the asset class and the market conditions. Depending on the security, the priority of the use of inputs may change or some market inputs may not be relevant. For some securities, additional inputs may be necessary. The pricing service utilized by the Company has indicated that it will only produce an estimate of fair value if there is objectively verifiable information to produce a valuation. If the pricing service discontinues pricing an investment, the Company would be required to produce an estimate of fair value using some of the same methodologies as the pricing service but would have to make assumptions for any market-based inputs that were unavailable due to market conditions. The Company reviews the estimates of fair value provided by the pricing service and compares the estimates to the Company’s knowledge of the market to determine if the estimates obtained are representative of the prices in the market. In addition, the Company has periodic discussions with the pricing service to discuss and understand any changes in process and their responsiveness to changes occurring in the markets. The Company also monitors all monthly price changes and further evaluates any securities whose value changed more than 10% from the prior month. The Company has implemented various other processes including randomly selecting purchased or sold securities and comparing execution prices to the estimates from the pricing service as well as reviewing securities whose valuation did not change from their previous valuation (stale price review). The Company also uses a second independent pricing service to further test the primary pricing service’s valuation of the Company’s fixed maturity portfolio. These processes have not highlighted any significant issues with the fair value estimates received from the primary pricing service. The fair value estimates of most fixed maturity investments are based on observable market information rather than market quotes. Accordingly, the estimates of fair value for such fixed maturities, other than U.S. Treasury securities, provided by the pricing service are included in the amount disclosed in Level 2 of the hierarchy. The estimated fair value of U.S. Treasury securities is included in the amount disclosed in Level 1 as the estimates are based on unadjusted market prices. The Company also holds certain fixed maturity investments which are not priced by the pricing service and, accordingly, estimates the fair value of such fixed maturities using an internal matrix that is based on market information regarding interest rates, credit spreads and liquidity. The underlying source data for calculating the matrix of credit spreads relative to the U.S. Treasury curve are observable market-based indices that relate to corporate and high-yield fixed maturity investments. The Company includes the fair value estimates of these corporate bonds in Level 2, since all significant inputs are market observable. While the vast majority of the Company’s fixed maturities are included in Level 2, the Company holds a number of municipal bonds and corporate bonds which are not valued by the pricing service and also estimates the fair value of these bonds using another internal pricing matrix that includes some unobservable inputs that are significant to the valuation. Due to the limited amount of observable market information, the Company includes the fair value estimates for these particular bonds in Level 3. The fair value of the fixed maturities for which the Company used this internal pricing matrix was $73 million and $82 million at December 31, 2019 and 2018 , respectively. Additionally, the Company holds a small amount of other fixed maturity investments that have characteristics that make them unsuitable for matrix pricing. For these fixed maturities, the Company obtains a quote from a broker (primarily the market maker). The fair value of the fixed maturities for which the Company received a broker quote was $28 million and $104 million at December 31, 2019 and 2018 , respectively. Due to the disclaimers on the quotes that indicate that the price is indicative only, the Company includes these fair value estimates in Level 3. Equity Securities — Public Common Stock and Non-Redeemable Preferred Stock For public common stock and non-redeemable preferred stocks, the Company receives prices from pricing services that are based on observable market transactions and includes these estimates in the amount disclosed in Level 1. When current market quotes in active markets are unavailable for certain non-redeemable preferred stocks held by the Company, the Company receives an estimate of fair value from the pricing services. The services utilize similar methodologies to price the non-redeemable preferred stocks as they do for the fixed maturities. The Company includes the fair value estimate for these non-redeemable preferred stocks in the amount disclosed in Level 2. Other Investments The Company holds investments in various publicly-traded securities which are reported in other investments. These investments include mutual funds and other small holdings. The $16 million fair value of these investments at both December 31, 2019 and 2018 was disclosed in Level 1. At December 31, 2019 and 2018 , the Company held investments in non-public common and preferred equity securities, with fair value estimates of $20 million and $36 million , respectively, reported in other investments, where the fair value estimate is determined either internally or by an external fund manager based on recent filings, operating results, balance sheet stability, growth and other business and market sector fundamentals. Due to the significant unobservable inputs in these valuations, the Company includes the total fair value estimate for all of these investments at December 31, 2019 and 2018 in the amount disclosed in Level 3. Other Liabilities The Company has a put/call option that was entered into in connection with a business acquisition that allows the Company to acquire the remaining shares of the acquired company at a future date. The fair value of the put/call at December 31, 2019 and 2018 was $8 million and $10 million , respectively, and was determined using an internal model and is based on the acquired company's financial performance, adjusted for a risk margin and discounted to present value. The Company includes the fair value estimate of the put/call in Level 3. Fair Value Hierarchy The following tables present the level within the fair value hierarchy at which the Company’s financial assets and financial liabilities are measured on a recurring basis. (at December 31, 2019, in millions) Total Level 1 Level 2 Level 3 Invested assets: Fixed maturities U.S. Treasury securities and obligations of U.S. government and government agencies and authorities $ 2,095 $ 2,095 $ — $ — Obligations of states, municipalities and political subdivisions 29,917 — 29,905 12 Debt securities issued by foreign governments 1,173 — 1,173 — Mortgage-backed securities, collateralized mortgage obligations and pass-through securities 3,280 — 3,280 — All other corporate bonds 31,619 — 31,530 89 Redeemable preferred stock 50 — 50 — Total fixed maturities 68,134 2,095 65,938 101 Equity securities Public common stock 383 383 — — Non-redeemable preferred stock 42 13 29 — Total equity securities 425 396 29 — Other investments 36 16 — 20 Total $ 68,595 $ 2,507 $ 65,967 $ 121 Other liabilities $ 8 $ — $ — $ 8 (at December 31, 2018, in millions) Total Level 1 Level 2 Level 3 Invested assets: Fixed maturities U.S. Treasury securities and obligations of U.S. government and government agencies and authorities $ 2,064 $ 2,064 $ — $ — Obligations of states, municipalities and political subdivisions 28,611 — 28,599 12 Debt securities issued by foreign governments 1,257 — 1,257 — Mortgage-backed securities, collateralized mortgage obligations and pass-through securities 2,573 — 2,554 19 All other corporate bonds 28,880 — 28,725 155 Redeemable preferred stock 79 3 76 — Total fixed maturities 63,464 2,067 61,211 186 Equity securities Public common stock 316 316 — — Non-redeemable preferred stock 52 30 22 — Total equity securities 368 346 22 — Other investments 52 16 — 36 Total $ 63,884 $ 2,429 $ 61,233 $ 222 Other liabilities $ 10 $ — $ — $ 10 The following tables present the changes in the Level 3 fair value category for the years ended December 31, 2019 and 2018 . (in millions) Fixed Maturities Other Investments Total Balance at December 31, 2018 $ 186 $ 36 $ 222 Total realized and unrealized investment gains (losses): Reported in net realized investment gains (1) — 3 3 Reported in increases in other comprehensive income (loss) 4 — 4 Purchases, sales and settlements/maturities: Purchases 38 6 44 Sales (1 ) (25 ) (26 ) Settlements/maturities (19 ) — (19 ) Gross transfers into Level 3 — — — Gross transfers out of Level 3 (107 ) — (107 ) Balance at December 31, 2019 $ 101 $ 20 $ 121 Amount of total realized investment gains (losses) for the period included in the consolidated statement of income attributable to changes in the fair value of assets still held at the reporting date $ — $ — $ — ___________________________________________ (1) Includes impairments on investments held at the end of the period as well as amortization on fixed maturities. The Company also includes in Level 3 the put/call option entered into in connection with a business acquisition that is reported in other liabilities and had a fair value of $8 million at December 31, 2019 . (in millions) Fixed Maturities Other Investments Total Balance at December 31, 2017 $ 204 $ 38 $ 242 Total realized and unrealized investment gains (losses): Reported in net realized investment gains (1) 2 7 9 Reported in increases in other comprehensive income (loss) (4 ) — (4 ) Purchases, sales and settlements/maturities: Purchases 146 3 149 Sales (11 ) (12 ) (23 ) Settlements/maturities (71 ) — (71 ) Gross transfers into Level 3 11 — 11 Gross transfers out of Level 3 (91 ) — (91 ) Balance at December 31, 2018 $ 186 $ 36 $ 222 Amount of total realized investment gains (losses) for the period included in the consolidated statement of income attributable to changes in the fair value of assets still held at the reporting date $ — $ — $ — ___________________________________________ (1) Includes impairments on investments held at the end of the period as well as amortization on fixed maturities. The Company also includes in Level 3 the put/call option entered into in connection with a business acquisition that is reported in other liabilities and had a fair value of $10 million at December 31, 2018 . Financial Instruments Disclosed, But Not Carried, At Fair Value The following tables present the carrying value and fair value of the Company’s financial assets and financial liabilities disclosed, but not carried, at fair value, and the level within the fair value hierarchy at which such assets and liabilities are categorized. (at December 31, 2019, in millions) Carrying Value Fair Value Level 1 Level 2 Level 3 Financial assets: Short-term securities $ 4,943 $ 4,943 $ 685 $ 4,204 $ 54 Financial liabilities: Debt $ 6,458 $ 8,049 $ — $ 8,049 $ — Commercial paper 100 100 — 100 — (at December 31, 2018, in millions) Carrying Value Fair Value Level 1 Level 2 Level 3 Financial assets: Short-term securities $ 3,985 $ 3,985 $ 632 $ 3,316 $ 37 Financial liabilities: Debt $ 6,464 $ 7,128 $ — $ 7,128 $ — Commercial paper 100 100 — 100 — The Company had no material assets or liabilities that were measured at fair value on a non-recurring basis during the years ended December 31, 2019 and 2018 .

Reinsurance

Reinsurance	12 Months Ended
Reinsurance	Dec. 31, 2019
Reinsurance Disclosures [Abstract]
Reinsurance	REINSURANCE The Company’s consolidated financial statements reflect the effects of assumed and ceded reinsurance transactions. Assumed reinsurance refers to the acceptance of certain insurance risks that other insurance companies have underwritten. Ceded reinsurance involves transferring certain insurance risks (along with the related written and earned premiums) the Company has underwritten to other insurance companies who agree to share these risks. The primary purpose of ceded reinsurance is to protect the Company, at a cost, from losses in excess of the amount it is prepared to accept and to protect the Company’s capital. Reinsurance is placed on both a quota-share and excess-of-loss basis. Ceded reinsurance arrangements do not discharge the Company as the primary insurer, except for instances where the primary policy or policies have been novated, such as in certain structured settlement agreements. The Company utilizes a corporate catastrophe excess-of-loss reinsurance treaty with unaffiliated reinsurers to manage its exposure to losses resulting from catastrophes and to protect its capital. In addition to the coverage provided under this treaty, the Company also utilizes a reinsurance agreement entered into in connection with catastrophe bonds issued by Long Point Re III to protect against certain weather-related and earthquake losses in the Northeastern United States, a Northeast property catastrophe excess-of-loss reinsurance treaty to protect against losses resulting from weather-related and earthquake catastrophes in the Northeastern United States and an underlying property aggregate catastrophe excess-of-loss reinsurance treaty to protect against the accumulation of certain property losses in North America. The Company also utilizes excess-of-loss treaties to protect against earthquake losses up to a certain threshold in Business Insurance (for certain markets) and for Personal Insurance, and several reinsurance treaties specific to its international operations. The Company monitors the financial condition of its reinsurers under voluntary reinsurance arrangements to evaluate the collectability of amounts due from reinsurers and as a basis for determining the reinsurers with which the Company conducts ongoing business. In addition, in the ordinary course of business, the Company may become involved in coverage disputes with its reinsurers. Some of these disputes could result in lawsuits and arbitrations brought by or against the reinsurers to determine the Company’s rights and obligations under the various reinsurance agreements. The Company employs dedicated specialists and strategies to manage reinsurance collections and disputes. Included in reinsurance recoverables are amounts related to involuntary reinsurance arrangements. The Company is required to participate in various involuntary reinsurance arrangements through assumed reinsurance, principally with regard to residual market mechanisms in workers’ compensation and automobile insurance, as well as homeowners’ insurance in certain coastal areas. In addition, the Company provides services for several of these involuntary arrangements (mandatory pools and associations) under which it writes such residual market business directly, then cedes 100% of this business to the mandatory pool. Such participations and servicing arrangements are arranged to mitigate credit risk to the Company, as any ceded balances are jointly backed by all the pool members. Also included in reinsurance recoverables are amounts related to certain structured settlements. Structured settlements are annuities purchased from various life insurance companies to settle certain personal physical injury claims, of which workers’ compensation claims comprise a significant portion. In cases where the Company did not receive a release from the claimant, the structured settlement is included in reinsurance recoverables and the related claim cost is included in the liability for claims and claim adjustment expense reserves, as the Company retains the contingent liability to the claimant. If it is expected that the life insurance company is not able to pay, the Company would recognize an impairment of the related reinsurance recoverable if, and to the extent, the purchased annuities are not covered by state guaranty associations. In the event that the life insurance company fails to make the required annuity payments, the Company would be required to make such payments. The following is a summary of reinsurance financial data reflected in the consolidated statement of income: (for the year ended December 31, in millions) 2019 2018 2017 Written premiums Direct $ 30,022 $ 28,210 $ 26,648 Assumed 1,041 1,042 1,000 Ceded (1,912 ) (1,544 ) (1,429 ) Total net written premiums $ 29,151 $ 27,708 $ 26,219 Earned premiums Direct $ 28,994 $ 27,536 $ 26,189 Assumed 1,076 1,024 965 Ceded (1,798 ) (1,501 ) (1,471 ) Total net earned premiums $ 28,272 $ 27,059 $ 25,683 Percentage of assumed earned premiums to net earned premiums 3.8 % 3.8 % 3.8 % Ceded claims and claim adjustment expenses incurred $ 1,089 $ 1,293 $ 1,225 Ceded premiums include the premiums paid for coverage provided by the Company’s catastrophe bonds. Reinsurance recoverables include amounts recoverable on both paid and unpaid claims and claim adjustment expenses and were as follows: (at December 31, in millions) 2019 2018 Gross reinsurance recoverables on paid and unpaid claims and claim adjustment expenses $ 3,476 $ 3,485 Allowance for uncollectible reinsurance (92 ) (110 ) Net reinsurance recoverables 3,384 3,375 Mandatory pools and associations 1,886 2,005 Structured settlements 2,965 2,990 Total reinsurance recoverables $ 8,235 $ 8,370 Terrorism Risk Insurance Program The Terrorism Risk Insurance Program is a Federal program administered by the Department of the Treasury authorized through December 31, 2027 that provides for a system of shared public and private compensation for certain insured losses resulting from certified acts of terrorism. In order for a loss to be covered under the program (subject losses), the loss must meet certain aggregate industry loss minimums and must be the result of an event that is certified as an act of terrorism by the U.S. Secretary of the Treasury, in consultation with the Secretary of Homeland Security and the Attorney General of the United States. The annual aggregate industry loss minimum under the program is $200 million . The program excludes from participation the following types of insurance: Federal crop insurance, private mortgage insurance, financial guaranty insurance, medical malpractice insurance, health or life insurance, flood insurance, reinsurance, commercial automobile, professional liability (other than directors' and officers’), surety, burglary and theft, and farm-owners multi-peril. In the case of a war declared by Congress, only workers’ compensation losses are covered by the program. All commercial property and casualty insurers licensed in the United States are generally required to participate in the program. Under the program, a participating insurer, in exchange for making terrorism insurance available, is entitled to be reimbursed by the Federal Government for 80% of subject losses, after an insurer deductible, subject to an annual cap. The deductible for any calendar year is equal to 20% of the insurer’s direct earned premiums for covered lines for the preceding calendar year. The Company’s estimated deductible under the program is $2.61 billion for 2020 . The annual cap limits the amount of aggregate subject losses for all participating insurers to $100 billion . Once subject losses have reached the $100 billion aggregate during a program year, participating insurers will not be liable under the program for additional covered terrorism losses for that program year. There have been no terrorism-related losses that have triggered program coverage since the program was established. Since the law is untested, there is substantial uncertainty as to how it will be applied if an act of terrorism is certified under the program. It is also possible that future legislative action could change or eliminate the program. Further, given the unpredictable frequency and severity of terrorism losses, as well as the limited terrorism coverage in the Company’s own reinsurance program, future losses from acts of terrorism, particularly involving nuclear, biological, chemical or radiological events, could be material to the Company’s operating results, financial position and/or liquidity in future periods. In addition, the Company may not have sufficient resources to respond to claims arising from a high frequency of high severity natural catastrophes and/or of man-made catastrophic events involving conventional means. While the Company seeks to manage its exposure to man-made catastrophic events involving conventional means, the Company may not have sufficient resources to respond to claims arising out of one or more man-made catastrophic events involving nuclear, biological, chemical or radiological means.

Goodwill and Other Intangible A

Goodwill and Other Intangible Assets	12 Months Ended
Goodwill and Other Intangible Assets	Dec. 31, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Other Intangible Assets	GOODWILL AND OTHER INTANGIBLE ASSETS Goodwill The following table presents the carrying amount of the Company’s goodwill by segment. Each reportable segment includes goodwill associated with the Company’s international business which is subject to the impact of changes in foreign currency exchange rates. (at December 31, in millions) 2019 2018 Business Insurance $ 2,601 $ 2,585 Bond & Specialty Insurance 550 550 Personal Insurance 784 776 Other 26 26 Total $ 3,961 $ 3,937 Other Intangible Assets The following tables present a summary of the Company’s other intangible assets by major asset class: (at December 31, 2019, in millions) Gross Carrying Amount Accumulated Amortization Net Subject to amortization Customer-related $ 99 $ 21 $ 78 Contract-based (1) 205 179 26 Total subject to amortization 304 200 104 Not subject to amortization 226 — 226 Total $ 530 $ 200 $ 330 (at December 31, 2018, in millions) Gross Carrying Amount Accumulated Amortization Net Subject to amortization Customer-related $ 98 $ 12 $ 86 Contract-based (1) 208 175 33 Total subject to amortization 306 187 119 Not subject to amortization 226 — 226 Total $ 532 $ 187 $ 345 ___________________________________________ (1) Contract-based intangible assets subject to amortization are comprised of fair value adjustments on claims and claim adjustment expense reserves, reinsurance recoverables and other contract-related intangible assets. Fair value adjustments recorded in connection with insurance acquisitions were based on management’s estimate of nominal claims and claim adjustment expense reserves and reinsurance recoverables. The method used calculated a risk adjustment to a risk-free discounted reserve that would, if reserves ran off as expected, produce results that yielded the assumed cost-of-capital on the capital supporting the loss reserves. The fair value adjustments are reported as other intangible assets on the consolidated balance sheet, and the amounts measured in accordance with the acquirer’s accounting policies for insurance contracts have been reported as part of the claims and claim adjustment expense reserves and reinsurance recoverables. The intangible assets are being recognized into income over the expected payment pattern. Because the time value of money and the risk adjustment (cost of capital) components of the intangible assets run off at different rates, the amount recognized in income may be a net benefit in some periods and a net expense in other periods. Amortization expense of intangible assets was $15 million , $17 million and $13 million for the years ended December 31, 2019 , 2018 and 2017 , respectively. Amortization expense for all intangible assets subject to amortization is estimated to be $15 million in 2020 , $14 million in 2021 , $13 million in 2022 , $12 million in 2023 and $12 million in 2024 . Amortization expense for intangible assets arising from insurance contracts acquired in a business combination is estimated to be $5 million in 2020 , $4 million in 2021 , $3 million in 2022 , $3 million in 2023 and $2 million in 2024

Insurance Claim Reserves

Insurance Claim Reserves	12 Months Ended
Insurance Claim Reserves	Dec. 31, 2019
Insurance Loss Reserves [Abstract]
Insurance Claim Reserves	INSURANCE CLAIM RESERVES Claims and claim adjustment expense reserves were as follows: (at December 31, in millions) 2019 2018 Property-casualty $ 51,836 $ 50,653 Accident and health 13 15 Total $ 51,849 $ 50,668 The following table presents a reconciliation of beginning and ending property casualty reserve balances for claims and claim adjustment expenses: (at and for the year ended December 31, in millions) 2019 2018 2017 Claims and claim adjustment expense reserves at beginning of year $ 50,653 $ 49,633 $ 47,929 Less reinsurance recoverables on unpaid losses 8,182 8,123 7,981 Net reserves at beginning of year 42,471 41,510 39,948 Estimated claims and claim adjustment expenses for claims arising in the current year 18,854 18,614 17,846 Estimated increase (decrease) in claims and claim adjustment expenses for claims arising in prior years 164 (406 ) (458 ) Total increases 19,018 18,208 17,388 Claims and claim adjustment expense payments for claims arising in: Current year 7,734 7,697 7,335 Prior years 10,060 9,363 8,708 Total payments 17,794 17,060 16,043 Unrealized foreign exchange loss (gain) 106 (187 ) 217 Net reserves at end of year 43,801 42,471 41,510 Plus reinsurance recoverables on unpaid losses 8,035 8,182 8,123 Claims and claim adjustment expense reserves at end of year $ 51,836 $ 50,653 $ 49,633 Gross claims and claim adjustment expense reserves at December 31, 2019 increased by $1.18 billion over December 31, 2018 , primarily reflecting the impacts of higher volumes of insured exposures and loss cost trends for the current accident year. Gross claims and claim adjustment expense reserves at December 31, 2018 increased by $1.02 billion over December 31, 2017 , primarily reflecting the impacts of (i) higher volumes of insured exposures and loss cost trends for the current accident year and (ii) catastrophe losses in 2018, partially offset by the impacts of (iii) payments related to catastrophe losses incurred in 2017 and (iv) net favorable prior year reserve development. Reinsurance recoverables on unpaid losses at December 31, 2019 decreased by $147 million from December 31, 2018 , primarily reflecting a decrease in recoverables related to mandatory pools and associations. Reinsurance recoverables on unpaid losses at December 31, 2018 increased by $59 million over December 31, 2017 , primarily reflecting the 2018 impacts of catastrophe losses and the asbestos reserve increase, partially offset by cash collections. The Company continues to evaluate the impact of recent developments on the estimated realizable value of its subrogation claims related to the 2017 and 2018 California wildfires. Recent developments include (i) the approval of Restructuring Support Agreements (RSAs) by the United States Bankruptcy Court reflecting the settlement of subrogation claims and individual wildfire victim claims against Pacific Gas & Electric Company (PG&E) and a settlement between bondholders and PG&E, and (ii) objections to PG&E's plan of reorganization raised by the Governor of California and others. The RSAs may be terminated if PG&E's plan of reorganization is not confirmed by June 30, 2020. Due to the risks and uncertainties associated with the PG&E bankruptcy and other factors, the Company has not yet recognized a subrogation benefit related to these claims. Included in the claims and claim adjustment expense reserves are reserves for long-term disability and annuity claim payments, primarily arising from workers’ compensation insurance and workers’ compensation excess insurance policies, that are discounted to the present value of the estimated future payments. The discount rates used were a range of 3.5% to 5.0% at December 31, 2019 and 5.0% at December 31, 2018 . Total reserves net of the discount were $2.48 billion and $2.45 billion , and the related amount of discount was $1.16 billion and $1.16 billion , at December 31, 2019 and 2018 , respectively. Accretion of the discount is reported as part of “claims and claim adjustment expenses” in the consolidated statement of income and was $49 million , $49 million and $50 million in 2019 , 2018 and 2017 , respectively. Prior Year Reserve Development The following disclosures regarding reserve development are on a “net of reinsurance” basis. 2019 In 2019 , estimated claims and claim adjustment expenses incurred included $164 million of net unfavorable development for claims arising in prior years, including $60 million of net unfavorable prior year reserve development and $49 million of accretion of discount that impacted the Company's results of operations. Business Insurance . Net unfavorable prior year reserve development in 2019 totaled $258 million , primarily driven by the following: • General liability (excluding asbestos and environmental) - higher than expected loss experience in the segment's domestic operations for primary and excess coverages for multiple accident years, including the impact for accident years 2009 and prior related to the enactment of legislation by a number of states that extended the statute of limitations for childhood sexual molestation claims; • Commercial automobile - higher than expected loss experience in the segment's domestic operations for recent accident years; • Asbestos reserves - an increase of $220 million , primarily in the segment's domestic general liability product line; • Commercial multi-peril - higher than expected loss experience in the segment's domestic operations for recent accident years; and • Environmental reserves - an increase of $76 million , primarily in the segment's domestic general liability product line, Partially offset by: • Workers' compensation - better than expected loss experience in the segment's domestic operations for multiple accident years; and • Commercial property - better than expected loss experience in the segment's domestic operations for recent accident years. Bond & Specialty Insurance . Net favorable prior year reserve development in 2019 totaled $65 million , primarily driven by better than expected loss experience in the segment's domestic operations in the general liability product line for management liability coverages and in the fidelity and surety product line for multiple accident years. Personal Insurance . Net favorable prior year reserve development in 2019 totaled $133 million , primarily driven by better than expected loss experience in the segment's domestic operations in the automobile and homeowners and other product lines for recent accident years. 2018 In 2018 , estimated claims and claim adjustment expenses incurred included $406 million of net favorable development for claims arising in prior years, including $517 million of net favorable prior year reserve development and $49 million of accretion of discount that impacted the Company's results of operations. Business Insurance . Net favorable prior year reserve development in 2018 totaled $142 million , primarily driven by the following: • Workers' compensation - better than expected loss experience in the segment’s domestic operations for multiple accident years; and • Commercial property - better than expected loss experience in the segment’s domestic operations for recent accident years, Partially offset by: • Commercial automobile - higher than expected loss experience for recent accident years; • Asbestos reserves - an increase of $225 million , primarily in the segment's domestic general liability product line; • General liability (excluding asbestos and environmental) - higher than expected loss experience in the segment's domestic operations for both primary and excess coverages for multiple accident years; and • Environmental reserves - an increase of $55 million , primarily in the segment's domestic general liability product line. Bond & Specialty Insurance . Net favorable prior year reserve development in 2018 totaled $266 million , primarily driven by better than expected loss experience in the segment’s domestic operations in the general liability product line for management liability coverages for multiple accident years. Personal Insurance . Net favorable prior year reserve development in 2018 totaled $109 million , primarily driven by better than expected loss experience in the segment's domestic operations in the automobile product line for recent accident years. 2017 In 2017 , estimated claims and claim adjustment expenses incurred included $458 million of net favorable development for claims arising in prior years, including $592 million of net favorable prior year reserve development and $50 million of accretion of discount that impacted the Company's results of operations. Business Insurance . Net favorable prior year reserve development in 2017 totaled $439 million , primarily driven by the following: • Workers' compensation - better than expected loss experience in the segment's domestic operations for multiple accident years; • General liability (excluding an increase to asbestos and environmental reserves) - better than expected loss experience in the segment's domestic operations for both primary and excess coverages for multiple accident years; and • Commercial multi-peril - better than expected loss experience for liability coverages for multiple accident years, Partially offset by: • Asbestos reserves - an increase of $225 million , primarily in the segment's domestic general liability product line; • Commercial automobile - higher than expected loss experience for recent accident years; • Environmental reserves - an increase of $65 million , primarily in the segment's domestic general liability product line; and • International and other - higher than expected loss experience in Europe primarily due to the U.K. Ministry of Justice’s “Ogden” discount rate adjustment applied to lump sum bodily injury payouts. Bond & Specialty Insurance . Net favorable prior year reserve development in 2017 totaled $140 million , primarily driven by better than expected loss experience in the segment’s domestic operations in the general liability product line for management liability coverages for multiple accident years. Personal Insurance . Net favorable prior year reserve development in 2017 was not significant and totaled $13 million . Claims Development The following is a summary of claims and claim adjustment expense reserves, including certain components, for the Company’s major product lines by reporting segment at December 31, 2019 . (at December 31, 2019, in millions) Net Undiscounted Claims and Claim Adjustment Expense Reserves Discount (Net of Reinsurance) Subtotal: Net Claims and Claim Adjustment Expense Reserves Reinsurance Recoverables on Unpaid Losses (4) Claims and Claim Adjustment Expense Reserves Business Insurance General liability $ 7,749 $ (172 ) $ 7,577 $ 842 $ 8,419 Commercial property 887 — 887 389 1,276 Commercial multi-peril 3,784 — 3,784 175 3,959 Commercial automobile 3,237 — 3,237 259 3,496 Workers’ compensation (1) 16,184 (911 ) 15,273 745 16,018 Bond & Specialty Insurance General liability 1,824 — 1,824 108 1,932 Fidelity and surety 399 — 399 4 403 Personal Insurance Automobile 2,862 — 2,862 486 3,348 Homeowners (excluding Other) 1,168 — 1,168 57 1,225 International - Canada 739 — 739 19 758 Subtotal — claims and allocated claim adjustment expenses for the products presented in the development tables below 38,833 (1,083 ) 37,750 3,084 40,834 Other insurance contracts (2) 3,895 (5 ) 3,890 1,968 5,858 Unallocated loss adjustment expense reserves 2,104 — 2,104 39 2,143 Structured settlements (3) — — — 2,965 2,965 Other 57 — 57 (21 ) 36 Total property-casualty 44,889 (1,088 ) 43,801 8,035 51,836 Accident and health — — — 13 13 Total $ 44,889 $ (1,088 ) $ 43,801 $ 8,048 $ 51,849 ___________________________________________ (1) Net discount amount includes discount of $67 million on reinsurance recoverables for long-term disability and annuity claim payments. (2) Primarily includes residual market, international (other than operations in Canada within the Personal Insurance segment) and runoff assumed reinsurance business. (3) Includes structured settlements in cases where the Company did not receive a release from the claimant. (4) Total reinsurance recoverables (on paid and unpaid losses) at December 31, 2019 were $8.24 billion . The claim development tables that follow present, by accident year, incurred and cumulative paid claims and allocated claim adjustment expense on a historical basis. This claim development information is presented on an undiscounted, net of reinsurance basis for ten years, or the number of years for which claims incurred typically remain outstanding if less than ten years. The claim development tables also provide the historical average annual percentage payout of incurred claims by age, net of reinsurance, as supplementary information (identified as unaudited in the tables below). For Personal Insurance - International - Canada, the claim development information reflects the acquisition of The Dominion of Canada General Insurance Company (Dominion) in November 2013 on a retrospective basis (includes Dominion data for years prior to the Company’s acquisition of Dominion). Business Insurance General Liability ( dollars in millions ) For the Years Ended December 31, 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance Unaudited Accident Year IBNR Reserves Dec 31, 2019 Cumulative Number of Reported Claims 2010 $ 1,028 $ 1,031 $ 1,021 $ 959 $ 927 $ 912 $ 918 $ 908 $ 911 $ 900 $ 62 27,993 2011 1,004 1,074 1,065 998 972 935 913 908 922 69 27,557 2012 989 985 935 913 892 905 917 920 78 24,920 2013 965 975 958 940 927 933 975 104 22,625 2014 976 989 983 948 956 1,013 159 22,319 2015 998 956 923 967 1,057 165 21,360 2016 1,075 1,058 1,087 1,187 359 19,997 2017 1,133 1,143 1,196 530 18,014 2018 1,253 1,312 841 16,694 2019 1,447 1,231 12,167 Total $ 10,929 Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance Accident Year Unaudited 2010 $ 35 $ 139 $ 324 $ 487 $ 629 $ 702 $ 756 $ 781 $ 800 $ 814 2011 47 187 355 539 660 725 762 799 819 2012 32 150 295 489 589 699 754 811 2013 35 175 363 498 639 745 816 Liability for Claims 2014 37 163 321 515 640 750 And Allocated Claim 2015 36 137 336 558 740 Adjustment Expenses, 2016 35 191 421 649 Net of Reinsurance 2017 40 180 378 2018 42 202 2010 - Before 2019 51 2019 2010 Total $ 6,030 $ 4,899 $ 2,850 Total net liability $ 7,749 Average Annual Percentage Payout of Incurred Claims by Age, Net of Reinsurance Unaudited Years 1 2 3 4 5 6 7 8 9 10 3.6 % 12.6 % 18.0 % 18.9 % 14.0 % 9.8 % 5.8 % 4.3 % 2.1 % 1.6 % Commercial Property ( dollars in millions ) For the Years Ended December 31, 2015 2016 2017 2018 2019 Incurred Claims and Allocated Claims Adjustment Expenses, Net of Reinsurance Unaudited Accident Year IBNR Reserves December 31, 2019 Cumulative Number of Reported Claims 2015 $ 786 $ 750 $ 741 $ 731 $ 737 $ 8 20,162 2016 896 863 820 809 11 22,313 2017 1,209 1,177 1,151 11 25,066 2018 1,093 1,079 10 24,785 2019 1,069 84 22,186 Total $ 4,845 Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance Unaudited Liability for Claims Accident Year And Allocated Claim 2015 $ 376 $ 615 $ 681 $ 699 $ 717 Adjustment Expenses, 2016 441 685 745 767 Net of Reinsurance 2017 618 1,003 1,073 2018 561 928 2015 - Before 2019 610 2019 2015 Total $ 4,095 $ 750 $ 137 Total net liability $ 887 Average Annual Percentage Payout of Incurred Claims by Age, Net of Reinsurance Unaudited Years 1 2 3 4 5 53.6 % 32.6 % 7.5 % 2.5 % 2.5 % Commercial Multi-Peril ( dollars in millions ) For the Years Ended December 31, 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance Unaudited Accident Year IBNR Reserves December 31, 2019 Cumulative Number of Reported Claims 2010 $ 1,711 $ 1,826 $ 1,832 $ 1,861 $ 1,895 $ 1,892 $ 1,898 $ 1,885 $ 1,881 $ 1,868 $ 19 112,074 2011 2,235 2,244 2,269 2,286 2,296 2,287 2,283 2,279 2,272 25 125,867 2012 1,885 1,883 1,903 1,888 1,888 1,867 1,859 1,854 34 104,921 2013 1,615 1,623 1,620 1,609 1,591 1,600 1,599 38 83,818 2014 1,663 1,627 1,625 1,617 1,626 1,627 50 78,292 2015 1,568 1,625 1,593 1,597 1,606 92 71,635 2016 1,662 1,623 1,598 1,590 122 68,888 2017 1,872 1,928 1,956 266 71,220 2018 1,976 2,114 416 68,403 2019 2,017 715 70,798 Total $ 18,503 Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance Accident Year Unaudited 2010 $ 709 $ 1,180 $ 1,395 $ 1,579 $ 1,698 $ 1,763 $ 1,798 $ 1,819 $ 1,834 $ 1,840 2011 1,060 1,573 1,803 1,979 2,088 2,156 2,193 2,222 2,234 2012 795 1,246 1,424 1,590 1,699 1,752 1,780 1,804 2013 644 987 1,167 1,304 1,410 1,475 1,516 Liability for Claims 2014 628 956 1,154 1,328 1,448 1,512 And Allocated Claim 2015 595 970 1,144 1,310 1,409 Adjustment Expenses, 2016 585 950 1,133 1,278 Net of Reinsurance 2017 716 1,199 1,388 2018 792 1,302 2010 - Before 2019 707 2019 2010 Total $ 14,990 $ 3,513 $ 271 Total net liability $ 3,784 Average Annual Percentage Payout of Incurred Claims by Age, Net of Reinsurance Unaudited Years 1 2 3 4 5 6 7 8 9 10 38.9 % 23.2 % 10.8 % 9.3 % 6.2 % 3.5 % 1.9 % 1.3 % 0.7 % 0.3 % Commercial Automobile ( dollars in millions ) For the Years Ended December 31, 2015 2016 2017 2018 2019 Incurred Claims and Allocated Claims Adjustment Expenses, Net of Reinsurance Unaudited Accident Year IBNR Reserves December 31, 2019 Cumulative Number of Reported Claims 2015 $ 1,188 $ 1,202 $ 1,234 $ 1,283 $ 1,298 $ 48 173,545 2016 1,278 1,303 1,371 1,409 94 183,114 2017 1,386 1,501 1,524 219 191,166 2018 1,645 1,742 469 201,578 2019 1,835 838 167,863 Total $ 7,808 Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance Unaudited Liability for Claims Accident Year And Allocated Claim 2015 $ 405 $ 650 $ 885 $ 1,058 $ 1,181 Adjustment Expenses, 2016 412 688 931 1,158 Net of Reinsurance 2017 456 746 1,027 2018 515 848 2015 - Before 2019 539 2019 2015 Total $ 4,753 $ 3,055 $ 182 Total net liability $ 3,237 Average Annual Percentage Payout of Incurred Claims by Age, Net of Reinsurance Unaudited Years 1 2 3 4 5 29.8 % 19.2 % 17.9 % 14.7 % 9.5 % Workers’ Compensation ( dollars in millions ) For the Years Ended December 31, 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance Unaudited Accident Year IBNR Reserves December 31, 2019 Cumulative Number of Reported Claims 2010 $ 1,886 $ 2,042 $ 2,035 $ 2,056 $ 2,049 $ 2,052 $ 2,055 $ 2,021 $ 2,003 $ 1,984 $ 248 117,466 2011 2,284 2,303 2,347 2,350 2,379 2,385 2,363 2,348 2,320 319 136,801 2012 2,447 2,456 2,457 2,456 2,445 2,453 2,416 2,387 367 138,034 2013 2,553 2,545 2,540 2,506 2,463 2,423 2,354 408 134,091 2014 2,554 2,553 2,547 2,476 2,430 2,393 486 129,293 2015 2,644 2,585 2,505 2,441 2,372 636 123,163 2016 2,768 2,690 2,569 2,473 702 122,944 2017 2,779 2,681 2,584 918 120,900 2018 2,744 2,687 1,180 121,460 2019 2,680 1,619 107,298 Total $ 24,234 Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance Accident Year Unaudited 2010 $ 341 $ 750 $ 978 $ 1,133 $ 1,246 $ 1,321 $ 1,385 $ 1,430 $ 1,465 $ 1,490 2011 420 911 1,185 1,365 1,487 1,583 1,652 1,696 1,732 2012 443 940 1,217 1,394 1,536 1,629 1,689 1,735 2013 458 954 1,237 1,413 1,525 1,604 1,659 Liability for Claims 2014 455 944 1,224 1,399 1,505 1,581 And Allocated Claim 2015 430 893 1,154 1,310 1,411 Adjustment Expenses, 2016 421 873 1,118 1,272 Net of Reinsurance 2017 433 890 1,154 2018 440 919 2010 - Before 2019 466 2019 2010 Total $ 13,419 $ 10,815 $ 5,369 Total net liability $ 16,184 Average Annual Percentage Payout of Incurred Claims by Age, Net of Reinsurance Unaudited Years 1 2 3 4 5 6 7 8 9 10 17.8 % 19.7 % 11.2 % 7.2 % 5.1 % 3.7 % 2.8 % 2.0 % 1.7 % 1.3 % Bond & Specialty Insurance General Liability ( dollars in millions ) For the Years Ended December 31, 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance Unaudited Accident Year IBNR Reserves December 31, 2019 Cumulative Number of Reported Claims 2010 $ 571 $ 612 $ 679 $ 679 $ 661 $ 668 $ 653 $ 653 $ 657 $ 660 $ 16 5,677 2011 565 596 639 632 601 545 520 508 506 2 5,213 2012 538 591 614 605 601 599 605 593 60 4,865 2013 510 565 606 630 654 607 586 42 4,456 2014 549 571 563 518 473 452 32 4,356 2015 528 524 486 437 395 38 4,195 2016 512 511 504 520 91 4,326 2017 534 517 526 174 4,455 2018 530 548 243 4,393 2019 588 432 3,400 Total $ 5,374 Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance Accident Year Unaudited 2010 $ 33 $ 152 $ 291 $ 396 $ 482 $ 565 $ 597 $ 623 $ 631 $ 635 2011 33 143 249 324 414 447 476 490 496 2012 38 160 255 342 383 419 436 453 2013 34 154 252 352 400 434 451 Liability for Claims 2014 38 150 239 312 367 407 And Allocated Claim 2015 38 141 234 310 338 Adjustment Expenses, 2016 30 141 233 313 Net of Reinsurance 2017 38 155 262 2018 49 182 2010 - Before 2019 51 2019 2010 Total $ 3,588 $ 1,786 $ 38 Total net liability $ 1,824 Average Annual Percentage Payout of Incurred Claims by Age, Net of Reinsurance Unaudited Years 1 2 3 4 5 6 7 8 9 10 7.2 % 22.1 % 19.5 % 16.2 % 10.9 % 7.9 % 4.1 % 3.1 % 1.2 % 0.6 % Fidelity and Surety ( dollars in millions ) For the Years Ended December 31, 2015 2016 2017 2018 2019 IBNR Reserves December 31, 2019 Cumulative Number of Reported Claims Incurred Claims and Allocated Claims Adjustment Expenses, Net of Reinsurance Accident Year Unaudited 2015 $ 217 $ 191 $ 179 $ 145 $ 137 $ 32 834 2016 226 239 205 208 9 886 2017 244 271 240 22 905 2018 220 235 22 849 2019 203 116 592 Total $ 1,023 Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance Accident Year Unaudited Liability for Claims And Allocated Claim 2015 $ 32 $ 75 $ 87 $ 86 $ 88 Adjustment Expenses, 2016 54 121 142 149 Net of Reinsurance 2017 70 166 194 2018 64 171 2015 - Before 2019 49 2019 2015 Total $ 651 $ 372 $ 27 Total net liability $ 399 Average Annual Percentage Payout of Incurred Claims by Age, Net of Reinsurance Unaudited Years 1 2 3 4 5 26.0 % 37.3 % 10.1 % 1.3 % 1.3 % Personal Insurance Automobile ( dollars in millions ) For the Years Ended December 31, 2015 2016 2017 2018 2019 IBNR Reserves December 31, 2019 Cumulative Number of Reported Claims Incurred Claims and Allocated Claims Adjustment Expenses, Net of Reinsurance Accident Year Unaudited 2015 $ 2,186 $ 2,244 $ 2,236 $ 2,222 $ 2,219 $ 11 757,972 2016 2,779 2,791 2,772 2,752 44 922,014 2017 3,323 3,256 3,221 139 1,061,907 2018 3,281 3,269 347 1,048,084 2019 3,362 858 940,933 Total $ 14,823 Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance Accident Year Unaudited Liability for Claims And Allocated Claim 2015 $ 1,319 $ 1,768 $ 1,985 $ 2,109 $ 2,174 Adjustment Expenses, 2016 1,610 2,203 2,466 2,616 Net of Reinsurance 2017 1,912 2,575 2,887 2018 1,889 2,582 2015 - Before 2019 1,933 2019 2015 Total $ 12,192 $ 2,631 $ 231 Total net liability $ 2,862 Average Annual Percentage Payout of Incurred Claims by Age, Net of Reinsurance Unaudited Years 1 2 3 4 5 58.5 % 20.9 % 9.7 % 5.5 % 2.9 % Homeowners (excluding Other) ( dollars in millions ) For the Years Ended December 31, 2015 2016 2017 2018 2019 IBNR Reserves December 31, 2019 Cumulative Number of Reported Claims Incurred Claims and Allocated Claims Adjustment Expenses, Net of Reinsurance Accident Year Unaudited 2015 $ 1,438 $ 1,454 $ 1,461 $ 1,452 $ 1,443 $ 1 145,136 2016 1,556 1,547 1,525 1,511 8 143,949 2017 2,312 2,340 2,343 49 169,085 2018 2,610 2,574 112 185,384 2019 2,297 447 158,328 Total $ 10,168 Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance Accident Year Unaudited Liability for Claims And Allocated Claim 2015 $ 994 $ 1,333 $ 1,395 $ 1,421 $ 1,429 Adjustment Expenses, 2016 1,049 1,392 1,455 1,479 Net of Reinsurance 2017 1,471 2,059 2,197 2018 1,657 2,298 2015 - Before 2019 1,613 2019 2015 Total $ 9,016 $ 1,152 $ 16 Total net liability $ 1,168 Average Annual Percentage Payout of Incurred Claims by Age, Net of Reinsurance Unaudited Years 1 2 3 4 5 67.1 % 24.1 % 4.8 % 1.7 % 0.6 % International - Canada ( dollars in millions ) For the Years Ended December 31, IBNR Reserves December 31, 2019 Cumulative 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 Number of Accident Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance Reported Year Unaudited Claims 2010 $ 487 $ 488 $ 499 $ 514 $ 501 $ 493 $ 489 $ 482 $ 481 $ 477 $ 1 54,938 2011 459 438 446 441 434 427 422 417 408 (5 ) 55,773 2012 435 413 414 398 397 380 374 362 (2 ) 51,208 2013 485 478 469 457 444 443 433 — 54,251 2014 429 444 445 433 426 423 (9 ) 52,268 2015 361 360 360 356 358 10 45,203 2016 361 409 409 419 19 45,759 2017 346 381 403 34 46,769 2018 440 462 64 50,302 2019 445 110 44,796 Total $ 4,190 Accident Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance Year Unaudited 2010 $ 191 $ 292 $ 329 $ 369 $ 400 $ 430 $ 447 $ 459 $ 465 $ 468 2011 176 249 280 314 349 371 389 397 401 2012 165 231 262 288 316 333 342 347 2013 194 272 304 336 369 387 405 Liability for Claims 2014 189 265 302 331 362 384 And Allocated Claim 2015 162 226 253 282 307 Adjustment Expenses, 2016 211 283 310 343 Net of Reinsurance 2017 182 257 296 2018 219 305 2010 - Before 2019 216 2019 2010 Total $ 3,472 $ 718 $ 21 Total net liability $ 739 Average Annual Percentage Payout of Incurred Claims by Age, Net of Reinsurance Unaudited Years 1 2 3 4 5 6 7 8 9 10 45.5 % 18.4 % 8.0 % 7.8 % 7.4 % 5.2 % 3.6 % 1.9 % 1.1 % 0.7 % The incurred and paid amounts have been translated from the local currency to U.S. dollars using the December 31, 2019 spot rate for all years presented in the table above in order to isolate changes in foreign exchange rates from loss development. Methodology for Estimating Incurred But Not Reported (IBNR) Reserves Claims and claim adjustment expense reserves represent management’s estimate of the ultimate liability for unpaid losses and loss adjustment expenses for claims that have been reported and claims that have been incurred but not yet reported (IBNR) as of the balance sheet date. Claims and claim adjustment expense reserves do not represent an exact calculation of the liability, but instead represent management estimates, primarily utilizing actuarial expertise and projection methods that develop estimates for the ultimate cost of claims and claim adjustment expenses. Because the establishment of claims and claims adjustment expense reserves is an inherently uncertain process involving estimates and judgment, currently estimated claims and claim adjustment expense reserves may change. The Company reflects changes to the reserves in the results of operations in the period the estimates are changed. Cumulative amounts paid and case reserves held as of the balance sheet date are subtracted from the estimate of the ultimate cost of claims and claim adjustment expenses to derive incurred but not reported (IBNR) reserves. Accordingly, IBNR reserves include the cost of unreported claims, development on known claims and re-opened claims. This approach to estimating IBNR reserves has been in place for many years, with no material changes in methodology in the past year. Detailed claim data is typically insufficient to produce a reliable indication of the initial estimate for ultimate claims and claim adjustment expenses for an accident year. As a result, the initial estimate for an accident year is generally based on an exposure-based method using either the loss ratio projection or the expected loss method. The loss ratio projection method, which is typically used for guaranteed-cost business, develops an initial estimate of ultimate claims and claim adjustment expenses for an accident year by multiplying earned premium for the accident year by a projected loss ratio. The projected loss ratio is determined by analyzing prior period experience, and adjusting for loss cost trends, rate level differences, mix of business changes and other known or observed factors influencing the accident year relative to prior accident years. The expected loss method, which is typically used for loss sensitive business, develops an initial estimate of ultimate claims and claim adjustment expenses for an accident year by analyzing exposures by account. For prior accident years, the following estimation and analysis methods are principally used by the Company’s actuaries to estimate the ultimate cost of claims and claim adjustment expenses. These estimation and analysis methods are typically referred to as conventional actuarial methods. • The paid loss development method assumes that the future change (positive or negative) in cumulative paid losses for a given cohort of claims will occur in a stable, predictable pattern from year-to-year, consistent with the pattern observed in past cohorts. • The case incurred development method is the same as the paid loss development method but is based on cumulative case-incurred losses rather than paid losses. • The Bornhuetter-Ferguson method uses an initial estimate of ultimate losses for a given product line reserve component, typically expressed as a ratio to earned premium. The method assumes that the ratio of additional claim activity to earned premium for that component is relatively stable and predictable over time and that actual claim activity to date is not a credible predictor of further activity for that component. The method is used most often for more recent accident years where claim data is sparse and/or volatile, with a transition to other methods as the underlying claim data becomes more voluminous and therefore more credible. • The average value analysis combined with the reported claim development method assumes that average claim values are stable and predictable over time for a particular cohort of claims. It is typically limited to analysis at more granular levels, such as coverage or hazard/peril, where a more homogeneous subset of claims produce a more stable and fairly predictable average value. The reported claim development method is the same as the paid loss development method but uses changes in cumulative claim counts to produce estimates of ultimate claim counts rather than ultimate dollars. The resulting estimate of ultimate claim counts by cohort is multiplied by an average value per claim from an average value analysis to obtain estimated ultimate claims and claim adjustment expenses. While these are the principal methods utilized, the Company’s actuaries have available to them the full range of actuarial methods developed by the casualty actuarial profession. The Company’s actuaries are also continually monitoring developments within the profession for advances in existing techniques or the creation of new techniques that might improve current and future estimates. Most actuarial methods assume that past patterns demonstrated in the data will repeat themselves in the future. For certain reserve components where this assumption may not hold, such as asbestos and environmental reserves, conventional actuarial methods are not utilized by the Company. Methodology for Determining Cumulative Number of Reported Claims A claim file is created when the Company is notified of an actual demand for payment, notified of an event that may lead to a demand for payment or when it is determined that a demand for payment could possibly lead to a future demand for payment on another coverage on the same policy or on another policy. Claim files are generally created for a policy at the claimant by coverage level, depending on the particular facts and circumstances of the underlying event. For Business Insurance and for Personal Insurance, claim file information is summarized such that the Company generally recognizes one count for each policy claim event by internal regulatory line of business, regardless of the number of claimants or coverages involved. The claims counts are then accumulated and reported by product line. While the methodology is generally consistent within each segment for the product lines displayed, there are some minor differences between and within segments. For Bond & Specialty Insurance, the Company generally recognizes one count per coverage per policy claim event and one count per bond per surety claim event. For purposes of the claims development tables above, claims reported for direct business are counted even if they eventually close with no loss payment, except in the case of (i) deductible business, where the claim is not counted until the ca

Debt

Debt	12 Months Ended
Debt	Dec. 31, 2019
Debt Disclosure [Abstract]
Debt	DEBT Debt outstanding was as follows: (at December 31, in millions) 2019 2018 Short-term: Commercial paper $ 100 $ 100 3.90% Senior notes due November 1, 2020 500 — 5.90% Senior notes due June 2, 2019 — 500 Total short-term debt 600 600 Long-term: 3.90% Senior notes due November 1, 2020 — 500 7.75% Senior notes due April 15, 2026 200 200 7.625% Junior subordinated debentures due December 15, 2027 125 125 6.375% Senior notes due March 15, 2033 500 500 6.75% Senior notes due June 20, 2036 400 400 6.25% Senior notes due June 15, 2037 800 800 5.35% Senior notes due November 1, 2040 750 750 4.60% Senior notes due August 1, 2043 500 500 4.30% Senior notes due August 25, 2045 400 400 8.50% Junior subordinated debentures due December 15, 2045 56 56 3.75% Senior notes due May 15, 2046 500 500 8.312% Junior subordinated debentures due July 1, 2046 73 73 4.00% Senior notes due May 30, 2047 700 700 4.05% Senior notes due March 7, 2048 500 500 4.10% Senior notes due March 4, 2049 500 — Total long-term debt 6,004 6,004 Total debt principal 6,604 6,604 Unamortized fair value adjustment 43 44 Unamortized debt issuance costs (89 ) (84 ) Total debt $ 6,558 $ 6,564 2019 Debt Issuance. On March 4, 2019, the Company issued $500 million aggregate principal amount of 4.10% senior notes that will mature on March 4, 2049. The net proceeds of the issuance, after the deduction of the underwriting discount and expenses payable by the Company, totaled approximately $492 million . Interest on the senior notes is payable semi-annually in arrears on March 4 and September 4. Prior to September 4, 2048, the senior notes may be redeemed, in whole or in part, at the Company’s option, at any time or from time to time, at a redemption price equal to the greater of (a) 100% of the principal amount of any senior notes to be redeemed or (b) the sum of the present values of the remaining scheduled payments of principal and interest to but excluding September 4, 2048 on any senior notes to be redeemed (exclusive of interest accrued to the date of redemption) discounted to the date of redemption on a semi-annual basis (assuming a 360-day year consisting of twelve 30-day months) at the then current Treasury rate (as defined in the senior notes), plus 20 basis points. On or after September 4, 2048, the senior notes may be redeemed, in whole or in part, at the Company’s option, at any time or from time to time, at a redemption price equal to 100% of the principal amount of any senior notes to be redeemed, plus accrued and unpaid interest to, but excluding, the redemption date. 2019 Debt Repayment . On June 2, 2019, the Company's $500 million , 5.90% senior notes matured and were fully paid. 2018 Debt Issuance. On March 7, 2018, the Company issued $500 million aggregate principal amount of 4.05% senior notes that will mature on March 7, 2048. The net proceeds of the issuance, after the deduction of the underwriting discount and expenses payable by the Company, totaled approximately $491 million . Interest on the senior notes is payable semi-annually in arrears on March 7 and September 7. Prior to September 7, 2047, the senior notes may be redeemed, in whole or in part, at the Company’s option, at any time or from time to time, at a redemption price equal to the greater of (a) 100% of the principal amount of any senior notes to be redeemed or (b) the sum of the present values of the remaining scheduled payments of principal and interest to but excluding September 7, 2047 on any senior notes to be redeemed (exclusive of interest accrued to the date of redemption) discounted to the date of redemption on a semi-annual basis (assuming a 360-day year consisting of twelve 30-day months) at the then current Treasury rate (as defined in the senior notes), plus 15 basis points. On or after September 7, 2047, the senior notes may be redeemed, in whole or in part, at the Company’s option, at any time or from time to time, at a redemption price equal to 100% of the principal amount of any senior notes to be redeemed, plus accrued and unpaid interest to, but excluding, the redemption date. 2018 Debt Repayment . On May 15, 2018, the Company's $500 million , 5.80% senior notes matured and were fully paid. 2017 Debt Issuance . On May 22, 2017, the Company issued $700 million aggregate principal amount of 4.00% senior notes that will mature on May 30, 2047. The net proceeds of the issuance, after the deduction of the underwriting discount and expenses payable by the Company, totaled approximately $689 million . Interest on the senior notes is payable semi-annually in arrears on May 30 and November 30. Prior to November 30, 2046, the senior notes may be redeemed, in whole or in part, at the Company’s option, at any time or from time to time, at a redemption price equal to the greater of (a) 100% of the principal amount of any senior notes to be redeemed or (b) the sum of the present values of the remaining scheduled payments of principal and interest to November 30, 2046 on any senior notes to be redeemed (exclusive of interest accrued to the date of redemption) discounted to the date of redemption on a semi-annual basis (assuming a 360-day year consisting of twelve 30-day months) at the then current Treasury rate (as defined in the senior notes), plus 15 basis points. On or after November 30, 2046, the senior notes may be redeemed, in whole or in part, at the Company’s option, at any time or from time to time, at a redemption price equal to 100% of the principal amount of any senior notes to be redeemed, plus accrued and unpaid interest to, but excluding, the redemption date. 2017 Debt Redemption and Repayment. On June 2, 2017, the Company redeemed the remaining $107 million aggregate principal amount of its 6.25% Fixed-to-Floating Rate Junior Subordinated Debentures due 2067 at a price per debenture of 100% of the principal amount thereof, plus accrued and unpaid interest to the redemption date. On December 15, 2017, the Company’s $450 million , 5.75% senior notes matured and were fully paid. Description of Debt Commercial Paper —The Company maintains an $800 million commercial paper program. Interest rates on commercial paper issued in 2019 ranged from 1.58% to 2.48% , and in 2018 ranged from 1.47% to 2.37% . Senior Notes —The Company’s various senior debt issues are unsecured obligations that rank equally with one another. Interest payments are made semi-annually. The Company generally may redeem some or all of the notes prior to maturity in accordance with terms unique to each debt instrument. Junior Subordinated Debentures —The Company’s three junior subordinated debenture instruments are all similar in nature to each other. Three separate business trusts issued preferred securities to investors and used the proceeds to purchase the Company’s junior subordinated debentures. Interest on each of the instruments is paid semi-annually. The Company’s consolidated balance sheet includes the debt instruments acquired in a business acquisition, which were recorded at fair value as of the acquisition date. The resulting fair value adjustment is being amortized over the remaining life of the respective debt instruments using the effective-interest method. The amortization of the fair value adjustment reduced interest expense by $1 million and $2 million for the years ended December 31, 2019 and 2018 , respectively. The following table presents merger-related unamortized fair value adjustments and the related effective interest rate: Unamortized Fair Value Purchase Adjustment at December 31, Effective Interest Rate to Maturity (in millions) Issue Rate Maturity Date 2019 2018 Junior subordinated debentures 7.625 % Dec. 2027 $ 11 $ 12 6.147 % 8.500 % Dec. 2045 14 14 6.362 % 8.312 % Jul. 2046 18 18 6.362 % Total $ 43 $ 44 The Travelers Companies, Inc. fully and unconditionally guarantees the payment of all principal, premiums, if any, and interest on certain debt obligations of its subsidiaries Travelers Property Casualty Corp. and Travelers Insurance Group Holdings, Inc. The guarantees pertain to the $200 million 7.75% notes due 2026 and the $500 million 6.375% notes due 2033. Maturities —The amount of debt obligations, other than commercial paper, that become due in each of the next five years is as follows: 2020 , $500 million ; 2021 , $0 ; 2022 , $0 ; 2023 , $0 ; and 2024 , $0 . Credit Agreement The Company is party to a five-year, $1.0 billion revolving credit agreement with a syndicate of financial institutions that expires on June 4, 2023. Pursuant to the credit agreement covenants, the Company must maintain a minimum consolidated net worth, defined as shareholders’ equity determined in accordance with GAAP (excluding accumulated other comprehensive income (loss)) plus (a) trust preferred securities (not to exceed 15% of total capital) and (b) mandatorily convertible securities (combined with trust preferred securities, not to exceed 25% of total capital) less goodwill and other intangible assets. The threshold is adjusted downward by an amount equal to 70% of the aggregate amount of common stock repurchased by the Company after March 31, 2018, up to a maximum deduction of $1.75 billion . The threshold was $12.55 billion at December 31, 2019 and could decline to a minimum of $12.494 billion during the term of the credit agreement, subject to the Company repurchasing an additional $80 million of its common stock. In addition, the credit agreement contains other customary restrictive covenants as well as certain customary events of default, including with respect to a change in control, which is defined to include the acquisition of 35% or more of the Company’s voting stock and certain changes in the composition of the Company’s Board of Directors. At December 31, 2019 , the Company was in compliance with these covenants. Generally, the cost of borrowing under this agreement will range from LIBOR plus 75 basis points to LIBOR plus 137.5 basis points, depending on the Company’s credit ratings. At December 31, 2019 , that cost would have been LIBOR plus 100 basis points, had there been any amounts outstanding under the credit agreement. In the event that LIBOR is no longer available, the credit agreement provides that the Company and the syndicate of financial institutions use commercially reasonable efforts to jointly agree upon an alternate rate of interest. Shelf Registration

Shareholders' Equity and Divide

Shareholders' Equity and Dividend Availability	12 Months Ended
Shareholders' Equity and Dividend Availability	Dec. 31, 2019
Stockholders' Equity Note [Abstract]
Shareholders' Equity and Dividend Availability	SHAREHOLDERS’ EQUITY AND DIVIDEND AVAILABILITY Authorized Shares The number of authorized shares of the Company is 1.755 billion , consisting of five million shares of preferred stock, 1.745 billion shares of voting common stock and five million undesignated shares. The Company’s Articles of Incorporation authorize the Board of Directors to establish, from the undesignated shares, one or more classes and series of shares, and to further designate the type of shares and terms thereof. Preferred Stock The Company’s Articles of Incorporation provide authority to issue up to five million shares of preferred stock. Common Stock The Company is governed by the Minnesota Business Corporation Act. All authorized shares of voting common stock have no par value. Shares of common stock reacquired are considered authorized and unissued shares. Restricted Stock At December 31, 2019 , 41,997 shares of restricted stock issued by the Company in August 2017 to certain employees of an acquired business remained outstanding and unvested. The restricted shares vest in August 2020 and are subject to service conditions. As a result, the value of the shares is recognized over the vesting period and is included with the share-based compensation cost of awards that are issued under the Company’s share-based incentive compensation plan (see note 13). Recipients generally have all the rights of a shareholder of the Company including the right to vote the applicable shares of common stock and to receive dividends on such shares, if and as declared by the Board of Directors. The restricted shares are held under the Company’s control with the Company’s transfer agent and will be released upon vesting. Treasury Stock The Company’s Board of Directors has approved common share repurchase authorizations under which repurchases may be made from time to time in the open market, pursuant to pre-set trading plans meeting the requirements of Rule 10b5-1 under the Securities Exchange Act of 1934, in private transactions or otherwise. The authorizations do not have a stated expiration date. The timing and actual number of shares to be repurchased in the future will depend on a variety of factors, including the Company’s financial position, earnings, share price, catastrophe losses, maintaining capital levels commensurate with the Company’s desired ratings from independent rating agencies, changes in levels of written premiums, funding of the Company’s qualified pension plan, capital requirements of the Company’s operating subsidiaries, legal requirements, regulatory constraints, other investment opportunities (including mergers and acquisitions and related financings), market conditions and other factors. In April 2017, the Board of Directors approved a share repurchase authorization that added an additional $5.0 billion of repurchase capacity. The following table summarizes repurchase activity in 2019 and remaining repurchase capacity at December 31, 2019 . (in millions, except per share amounts) Quarterly Period Ending Number of shares repurchased Cost of shares repurchased Average price paid per share Remaining capacity under share repurchase authorization March 31, 2019 2.9 $ 375 $ 129.42 $ 2,911 June 30, 2019 2.6 375 145.87 2,536 September 30, 2019 2.5 375 147.23 2,161 December 31, 2019 2.8 375 134.33 1,786 Total 10.8 $ 1,500 138.80 1,786 The Company’s Amended and Restated 2004 Stock Incentive Plan and the Amended and Restated 2014 Stock Incentive Plan provide settlement alternatives to employees in which the Company retains shares to cover payroll withholding taxes in connection with the vesting of restricted stock unit awards and performance share awards, and shares used by employees to cover the price of certain stock options that were exercised. During the years ended December 31, 2019 and 2018 , the Company acquired $48 million and $51 million , respectively, of its common stock under these plans. Common shares acquired are reported as treasury stock in the consolidated balance sheet. Dividend Availability The Company’s U.S. insurance subsidiaries, domiciled principally in the State of Connecticut, are subject to various regulatory restrictions that limit the maximum amount of dividends available to be paid by each insurance subsidiary to its respective parent company without prior approval of insurance regulatory authorities. A maximum of $2.79 billion is available by the end of 2020 for such dividends to the holding company, TRV, without prior approval of the Connecticut Insurance Department. The Company may choose to accelerate the timing within 2020 and/or increase the amount of dividends from its insurance subsidiaries in 2020 , which could result in certain dividends being subject to approval by the Connecticut Insurance Department. In addition to the regulatory restrictions on the availability of dividends that can be paid by the Company’s U.S. insurance subsidiaries, the maximum amount of dividends that may be paid to the Company’s shareholders is limited, to a lesser degree, by certain covenants contained in its line of credit agreement with a syndicate of financial institutions that require the Company to maintain a minimum consolidated net worth as described in note 8. TRV is not dependent on dividends or other forms of repatriation from its foreign operations to support its liquidity needs. The undistributed earnings of the Company’s foreign operations are intended to be permanently reinvested in those operations, and such earnings were not material to the Company's financial position or liquidity at December 31, 2019 . TRV and its two non-insurance holding company subsidiaries received dividends of $2.50 billion , $2.30 billion and $2.33 billion from their U.S. insurance subsidiaries in 2019 , 2018 and 2017 , respectively. For the years ended December 31, 2019 , 2018 and 2017 , TRV declared cash dividends per common share of $3.23 , $3.03 and $2.83 , respectively, and paid cash dividends of $844 million , $814 million and $785 million , respectively. Statutory Net Income and Statutory Capital and Surplus Statutory net income of the Company’s domestic and international insurance subsidiaries was $2.74 billion , $2.61 billion and $2.30 billion for the years ended December 31, 2019 , 2018 and 2017 , respectively. Statutory capital and surplus of the Company’s domestic and international insurance subsidiaries was $21.33 billion and $20.77 billion at December 31, 2019 and 2018 , respectively.

Other Comprehensive Income and

Other Comprehensive Income and Accumulated Other Comprehensive Income	12 Months Ended
	Dec. 31, 2019
Other Comprehensive Income And Accumulated Other Comprehensive Income Disclosure [Abstract]
Other Comprehensive Income and Accumulated Other Comprehensive Income	OTHER COMPREHENSIVE INCOME AND ACCUMULATED OTHER COMPREHENSIVE INCOME The following table presents the changes in the Company’s accumulated other comprehensive income (AOCI) for the years ended December 31, 2019 , 2018 and 2017 . Changes in Net Unrealized Gains (Losses) on Investment Securities (in millions) Having No Credit Losses Recognized in the Consolidated Statement of Income Having Credit Losses Recognized in the Consolidated Statement of Income Net Benefit Plan Assets and Obligations Recognized in Shareholders’ Equity Net Unrealized Foreign Currency Translation Total Accumulated Other Comprehensive Income (Loss) Balance, December 31, 2016 $ 528 $ 202 $ (703 ) $ (782 ) $ (755 ) Other comprehensive income (loss) (OCI) before reclassifications, net of tax 367 4 (24 ) 171 518 Amounts reclassified from AOCI, net of tax (148 ) 1 41 — (106 ) Net OCI, current period 219 5 17 171 412 Balance, December 31, 2017 747 207 (686 ) (611 ) (343 ) Cumulative effect of adoption of updated accounting guidance for equity financial instruments at January 1, 2018 (34 ) — — — (34 ) Income tax benefit (12 ) — — — (12 ) Net of taxes (22 ) — — — (22 ) Reclassification of certain tax effects from accumulated other comprehensive income at January 1, 2018 145 7 (141 ) (35 ) (24 ) Total effect of adoption of new guidance at January 1, 2018, net of tax 123 7 (141 ) (35 ) (46 ) OCI before reclassifications, net of tax (1,151 ) (21 ) (114 ) (227 ) (1,513 ) Amounts reclassified from AOCI, net of tax (25 ) — 68 — 43 Net OCI, current period (1,176 ) (21 ) (46 ) (227 ) (1,470 ) Balance, December 31, 2018 (306 ) 193 (873 ) (873 ) (1,859 ) OCI before reclassifications, net of tax 2,406 (4 ) (14 ) 106 2,494 Amounts reclassified from AOCI, net of tax (43 ) — 41 7 5 Net OCI, current period 2,363 (4 ) 27 113 2,499 Balance, December 31, 2019 $ 2,057 $ 189 $ (846 ) $ (760 ) $ 640 The following table presents the pre-tax components of the Company’s other comprehensive income (loss) and the related income tax expense (benefit). (for the year ended December 31, in millions) 2019 2018 2017 Changes in net unrealized gains (losses) on investment securities: Having no credit losses recognized in the consolidated statement of income $ 2,994 $ (1,489 ) $ 294 Income tax expense (benefit) 631 (313 ) 75 Net of taxes 2,363 (1,176 ) 219 Having credit losses recognized in the consolidated statement of income (4 ) (27 ) 8 Income tax expense (benefit) — (6 ) 3 Net of taxes (4 ) (21 ) 5 Net changes in benefit plan assets and obligations 33 (56 ) 29 Income tax expense (benefit) 6 (10 ) 12 Net of taxes 27 (46 ) 17 Net changes in unrealized foreign currency translation 117 (247 ) 191 Income tax expense (benefit) 4 (20 ) 20 Net of taxes 113 (227 ) 171 Total other comprehensive income (loss) 3,140 (1,819 ) 522 Total income tax expense (benefit) 641 (349 ) 110 Total other comprehensive income (loss), net of taxes $ 2,499 $ (1,470 ) $ 412 The following table presents the pre-tax and related income tax (expense) benefit components of the amounts reclassified from the Company’s AOCI to the Company’s consolidated statement of income. (for the year ended December 31, in millions) 2019 2018 2017 Reclassification adjustments related to unrealized gains (losses) on investment securities: Having no credit losses recognized in the consolidated statement of income (1) $ (55 ) $ (32 ) $ (228 ) Income tax expense (2) (12 ) (7 ) (80 ) Net of taxes (43 ) (25 ) (148 ) Having credit losses recognized in the consolidated statement of income (1) — — 1 Income tax benefit (2) — — — Net of taxes — — 1 Reclassification adjustment related to benefit plan assets and obligations: Claims and claim adjustment expenses (3) 21 35 32 General and administrative expenses (3) 31 51 48 Total 52 86 80 Income tax benefit (2) 11 18 39 Net of taxes 41 68 41 Reclassification adjustment related to foreign currency translation (1) 7 — — Income tax benefit (2) — — — Net of taxes 7 — — Total reclassifications 4 54 (147 ) Total income tax (expense) benefit (1 ) 11 (41 ) Total reclassifications, net of taxes $ 5 $ 43 $ (106 ) ___________________________________________ (1) (Increases) decreases net realized investment gains on the consolidated statement of income. (2) (Increases) decreases income tax expense on the consolidated statement of income. (3) Increases (decreases) expenses on the consolidated statement of income.

Earnings per Share

Earnings per Share	12 Months Ended
Earnings per Share	Dec. 31, 2019
Earnings Per Share Reconciliation [Abstract]
Earnings Per Share	EARNINGS PER SHARE Basic earnings per share was computed by dividing net income available to common shareholders by the weighted average number of common shares outstanding during the period. The computation of diluted earnings per share reflected the effect of potentially dilutive securities and excludes the effect of any anti-dilutive shares. Potentially dilutive securities include restricted stock units, deferred stock units, stock options and performance share awards related to the employee share-based incentive compensation programs. The restricted stock units and deferred stock units contain non-forfeitable rights to dividends and are included as participating securities in the calculation of basic and diluted earnings per share using the two-class method. Stock option and performance share awards are included in the calculation of diluted earnings per share using the treasury stock method. The following is a reconciliation of the income and share data used in the basic and diluted earnings per share computations: (for the year ended December 31, in millions, except per share amounts) 2019 2018 2017 Basic and Diluted Net income, as reported $ 2,622 $ 2,523 $ 2,056 Participating securities — allocated income (19 ) (19 ) (15 ) Net income available to common shareholders — basic and diluted $ 2,603 $ 2,504 $ 2,041 Common Shares Basic Weighted average shares outstanding 260.0 267.4 276.0 Diluted Weighted average shares outstanding 260.0 267.4 276.0 Weighted average effects of dilutive securities: Stock options and performance shares 2.3 2.4 2.6 Total 262.3 269.8 278.6 Net income Per Common Share 0 Basic $ 10.01 $ 9.37 $ 7.39 Diluted $ 9.92 $ 9.28 $ 7.33

Income Taxes

Income Taxes	12 Months Ended
Income Taxes	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Income Taxes	INCOME TAXES Components of Income Tax Expense The following table presents the components of income tax expense included in the amounts reported in the Company’s consolidated financial statements: (for the year ended December 31, in millions) 2019 2018 2017 Composition of income tax expense included in the consolidated statement of income Current expense: Federal $ 546 $ 424 $ 314 Impact of TCJA at enactment — — 21 Foreign 7 41 56 State 6 8 4 Total current tax expense 559 473 395 Deferred expense (benefit): Federal (33 ) (13 ) 229 Impact of TCJA at enactment — — 108 Foreign (10 ) (22 ) (58 ) Total deferred tax expense (benefit) (43 ) (35 ) 279 Total income tax expense included in the consolidated statement of income 516 438 674 Composition of income tax expense (benefit) included in shareholders’ equity Expense (benefit) relating to changes in the unrealized gain (loss) on investments, unrealized loss on foreign exchange and other items in other comprehensive income (loss) 641 (349 ) 110 Total income tax expense included in the consolidated financial statements $ 1,157 $ 89 $ 784 The following is a reconciliation of income tax expense at the U.S. federal statutory income tax rate to the income tax expense reported in the Company’s consolidated statement of income: (for the year ended December 31, in millions) 2019 2018 2017 Income (loss) before income taxes U.S. $ 3,211 $ 3,039 $ 2,798 Foreign (73 ) (78 ) (68 ) Total income before income taxes 3,138 2,961 2,730 Effective tax rate Statutory tax rate 21 % 21 % 35 % Expected federal income tax expense 659 622 956 Tax effect of: Nontaxable investment income (149 ) (150 ) (297 ) TCJA at enactment — — 129 Other, net 6 (34 ) (114 ) Total income tax expense $ 516 $ 438 $ 674 Effective tax rate 16 % 15 % 25 % The Company paid income taxes of $428 million , $408 million and $514 million during the years ended December 31, 2019 , 2018 and 2017 , respectively. The current income tax payable of $126 million at December 31, 2019 was included in other liabilities in the consolidated balance sheet. The current income tax receivable of $12 million at December 31, 2018 was included in other assets in the consolidated balance sheet. Tax Cuts and Jobs Act of 2017 On December 22, 2017, the U.S. enacted the Tax Cuts and Jobs Act of 2017 (TCJA) which, among other changes, reduced the U.S. federal tax rate from 35% to 21% beginning on January 1, 2018 and imposed a tax on undistributed and previously untaxed post-1986 foreign earnings and profits (accumulated foreign earnings). Total income tax expense for 2017 included a net charge of $129 million to reflect the estimated impacts of the changes in tax laws and tax rates included in TCJA at the date of enactment, primarily reflecting the revaluation of the Company's deferred tax assets and liabilities at the new statutory federal tax rate of 21%, and the recognition of tax imposed on accumulated foreign earnings. The estimated effects of enactment of TCJA were reflected in the Company's net deferred tax asset and current income tax receivable reported on the Company’s consolidated balance sheet at December 31, 2017. In computing taxable income, property and casualty insurers reduce underwriting income by claims and claim adjustment expenses incurred. The deduction for claims incurred is discounted at the interest rates and for the claim payment patterns prescribed by the U.S. Treasury. TCJA changed the prescribed interest rates to rates based on corporate bond yield curves and extended the applicable time periods for the claim payment pattern. These changes were effective for tax years beginning after 2017 and are subject to a transition rule that spreads the additional tax payment from the amount determined by applying these changes over the subsequent eight years beginning in 2018. This item is a taxable temporary difference and had no direct impact on total tax expense for 2017 and will not directly impact total tax expense in future years. The required additional tax payments are currently estimated to approximate $19 million per year through 2025 and will result in a modest reduction in net investment income over that period. The U.S. Treasury issued final regulations for the tax discounting of loss reserves that became effective in June 2019. The final regulations did not materially impact the Company’s amounts payable related to the transition rules for discounting loss reserves. During the fourth quarter of 2017, the Company recorded provisional amounts for the tax imposed on accumulated foreign earnings and partnership investments, as well as the amount due under the transition rule relating to the change in discounting of claims incurred, based on information available at December 31, 2017. In 2018, the Company made minor adjustments to the provisional amounts for taxes related to accumulated foreign earnings based upon final earnings from its foreign operations and the proposed regulations issued by the U.S. Treasury. These minor adjustments were consistent with final regulations issued by the U.S. Treasury in January 2019. The Company also made minor adjustments to the provisional amount for taxes related to partnership investments based upon the latest available information associated with those investments (Form K-1s) that were received in 2018 and 2019. Deferred Tax Asset (Liability) The net deferred tax asset (liability) comprises the tax effects of temporary differences related to the following assets and liabilities: (at December 31, in millions) 2019 2018 Deferred tax assets Claims and claim adjustment expense reserves $ 551 $ 571 Unearned premium reserves 539 503 Compensation-related liabilities 97 92 Other 243 200 Total gross deferred tax assets 1,430 1,366 Less: valuation allowance 27 8 Adjusted gross deferred tax assets 1,403 1,358 Deferred tax liabilities Claims and claim adjustment expense reserve discounting (transition rule) 115 159 Deferred acquisition costs 427 397 Investments 781 152 Internally developed software 94 92 Depreciation 70 67 Other 53 46 Total gross deferred tax liabilities 1,540 913 Net deferred tax asset (liability) $ (137 ) $ 445 If the Company determines that any of its deferred tax assets will not result in future tax benefits, a valuation allowance must be established for the portion of these assets that are not expected to be realized. The net change in the valuation allowance for deferred tax assets was an increase of $19 million in 2019 , $16 million relating to the Company's Republic of Ireland subsidiary, $2 million relating to the Company's consolidated Brazilian subsidiary and $1 million relating to the Company's Canadian subsidiary. Based upon a review of the Company’s anticipated future taxable income, and also including all other available evidence, both positive and negative, the Company’s management concluded that it is more likely than not that the net deferred tax assets will be realized. U.S. income taxes have not been recognized on any undistributed earnings that are intended to be permanently reinvested. After TCJA, any potential U.S. income tax on these amounts is immaterial. Net Operating Losses For tax return purposes, as of December 31, 2019 , the Company had net operating loss (NOL) carryforwards in the United States, Brazil, Canada, the Republic of Ireland and the United Kingdom. The amount and timing of realizing the benefits of NOL carryforwards depend on future taxable income and limitations imposed by tax laws. Only the benefits of the United Kingdom NOL carryforwards have been recognized in the consolidated financial statements and are included in net deferred tax assets. The NOL amounts by jurisdiction and year of expiration are as follows: (in millions) Amount Year of expiration United States $ 2 2035 - 2036 Brazil $ 25 None Canada $ 5 2035 - 2039 Republic of Ireland $ 124 None United Kingdom $ 202 None Uncertain Tax Positions The following is a reconciliation of the beginning and ending amount of unrecognized tax benefits for the years ended December 31, 2019 and 2018 : (in millions) 2019 2018 Balance at January 1 $ 31 $ 6 Additions for tax positions of prior years 8 25 Reductions for tax positions of prior years — — Reductions based on tax positions related to current year — — Expiration of statute of limitations $ (2 ) — Balance at December 31 $ 37 $ 31 Included in the balances at December 31, 2019 and 2018 were $34 million and $29 million , respectively, of unrecognized tax benefits that, if recognized, would affect the annual effective tax rate. Also included in the balances at those dates were $3 million and $2 million , respectively, of tax positions for which the ultimate deductibility is certain, but for which there is uncertainty about the timing of deductibility. The timing of such deductibility could affect the annual effective tax rate depending on the year of deduction and tax rate at the time. The Company recognizes accrued interest and penalties, if any, related to unrecognized tax benefits in income taxes. During the years ended December 31, 2019 , 2018 and 2017 , the Company recognized approximately $(1) million , $(10) million and $(33) million in interest, respectively. The Company had approximately $13 million and $14 million accrued for the payment of interest at December 31, 2019 and 2018 , respectively. The IRS is conducting an examination of the Company’s U.S. income tax returns for 2017 and 2018. The Company does not expect any significant changes to its liability for unrecognized tax benefits during the next twelve months.

Share-Based Incentive Compensat

Share-Based Incentive Compensation	12 Months Ended
Share-Based Incentive Compensation	Dec. 31, 2019
Share-based Payment Arrangement [Abstract]
Share-based Incentive Compensation	SHARE-BASED INCENTIVE COMPENSATION The Company has a share-based incentive compensation plan, The Travelers Companies, Inc. Amended and Restated 2014 Stock Incentive Plan (the 2014 Incentive Plan), the purposes of which are to align the interests of the Company’s non-employee directors, executive officers and other employees with those of the Company’s shareholders and to attract and retain personnel by providing incentives in the form of share-based awards. The 2014 Incentive Plan permits grants of nonqualified stock options, incentive stock options, stock appreciation rights, restricted stock, restricted stock units, deferred stock, deferred stock units, performance awards and other share-based or share-denominated awards with respect to the Company’s common stock. The Company has a policy of issuing new shares to settle the exercise of stock option awards and the vesting of other equity awards. In connection with the adoption of the 2014 Incentive Plan, The Travelers Companies, Inc. Amended and Restated 2004 Stock Incentive Plan, as amended (the 2004 Incentive Plan) was terminated, joining several other legacy share-based incentive compensation plans that had been terminated in prior years (together, the legacy plans). Outstanding grants were not affected by the termination of the legacy plans. The 2014 Incentive Plan is currently the only plan pursuant to which future stock-based awards may be granted. The number of shares of the Company’s common stock initially authorized for grant under the 2014 Incentive Plan was 10 million shares. In May 2019, 2017 and 2016, the Company’s shareholders authorized an additional 3.1 million , 2.5 million and 4.4 million shares of the Company’s common stock, respectively, for grant under the 2014 Incentive Plan. The following are not counted towards the combined 20.0 million shares available and will be available for future grants under the 2014 Incentive Plan: (i) shares of common stock subject to awards that expire unexercised, that are forfeited, terminated or canceled, that are settled in cash or other forms of property, or otherwise do not result in the issuance of shares of common stock, in whole or in part; (ii) shares that are used to pay the exercise price of stock options and shares used to pay withholding taxes on awards generally; and (iii) shares purchased by the Company on the open market using cash option exercise proceeds; provided, however, that the increase in the number of shares of common stock available for grant pursuant to such market purchases shall not be greater than the number that could be repurchased at fair market value on the date of exercise of the stock option giving rise to such option proceeds. In addition, the 20.0 million shares authorized by shareholders for issuance under the 2014 Incentive Plan will be increased by any shares subject to awards under the 2004 Incentive Plan that were outstanding as of May 27, 2014 and subsequently expire, are forfeited, canceled, settled in cash or otherwise terminate without the issuance of shares. The Company also has a compensation program for non-employee directors (the Director Compensation Program). Under the Director Compensation Program, non-employee directors’ compensation consists of an annual retainer, a deferred stock award, committee chair fees and a lead director fee. Each non-employee director may choose to receive all or a portion of his or her annual retainer, committee chair fee and lead director fee in the form of cash or deferred stock units which vest upon grant. The annual deferred stock awards vest in full one day prior to the date of the Company’s annual meeting of shareholders occurring in the year following the year of the grant date, subject to continued service. The deferred stock awards, including dividend equivalents, accumulate until distribution either in a lump sum six months after termination of service as a director or, if the director so elects, in annual installments beginning at least six months following termination of service as a director. The deferred stock units issued under the Director Compensation Program are awarded under the 2014 Incentive Plan. Stock Option Awards Stock option awards granted to eligible officers and key employees have a ten -year term. All stock options are granted with an exercise price equal to the closing price of the Company’s common stock on the date of grant. The stock options granted generally vest upon meeting certain years of service criteria. Except as the Compensation Committee of the Board of Directors may allow in the future, stock options cannot be sold or transferred by the participant. Stock options outstanding under the 2014 Incentive Plan and the 2004 Incentive Plan generally vest three years after grant date (cliff vest). The fair value of each option award is estimated on the date of grant by application of a variation of the Black-Scholes option pricing model using the assumptions noted in the following table. The expected term of newly granted stock options is the time to vest plus half the remaining time to expiration. This considers the vesting restriction and represents an even pattern of exercise behavior over the remaining term. The expected volatility assumption is based on the historical volatility of the Company’s common stock for the same period as the estimated option term generally using the volatility of the week prior to the stock option grant. The expected dividend is based upon the Company’s current quarter dividend annualized and assumed to be constant over the expected option term. The risk-free interest rate for each option is the interpolated market yield of a U.S. Treasury bill with a term comparable to the expected option term for the same week used for measuring volatility. The following table provides information about options granted: (for the year ended December 31,) 2019 2018 2017 Assumptions used in estimating fair value of options on grant date Expected term of stock options 6 years 6 years 6 years Expected volatility of Company’s stock 15.47% - 15.91% 14.94 % 16.50 % Weighted average volatility 15.48 % 14.94 % 16.50 % Expected annual dividend per share $3.08 - $3.28 $2.88 $2.68 Risk-free rate 1.70% - 2.54% 2.68 % 2.08 % Additional information Weighted average grant-date fair value of options granted (per share) $ 16.64 $ 20.13 $ 16.15 Total intrinsic value of options exercised during the year (in millions) $ 88 $ 67 $ 90 A summary of stock option activity under the 2014 Incentive Plan and the legacy plans as of and for the year ended December 31, 2019 is as follows: Stock Options Number Weighted Average Exercise Price Weighted Average Contractual Life Remaining Aggregate Intrinsic Value ($ in millions) Outstanding, beginning of year 8,994,356 $ 106.93 Original grants 2,057,494 126.19 Exercised (1,874,412 ) 92.98 Forfeited or expired (114,164 ) 127.55 Outstanding, end of year 9,063,274 $ 113.93 6.3 years $ 215 Vested at end of year (1) 6,025,208 $ 106.91 5.3 years $ 184 Exercisable at end of year 4,001,010 $ 96.37 3.9 years $ 163 ___________________________________________ (1) Represents awards for which the requisite service has been rendered, including those that are retirement eligible. On February 4, 2020, the Company, under the 2014 Incentive Plan, granted 2,474,036 stock option awards with an exercise price of $132.58 per share. The fair value attributable to the stock option awards on the date of grant was $14.41 per share. Restricted Stock Units, Deferred Stock Units and Performance Share Award Programs The Company issues restricted stock unit awards to eligible officers and key employees under the Equity Awards program established pursuant to the 2014 Incentive Plan. A restricted stock unit represents the right to receive a share of common stock. These restricted stock unit awards are granted at market price, generally vest three years from the date of grant, do not have voting rights and the underlying shares of common stock are not issued until the vesting criteria is satisfied. In addition, members of the Company’s Board of Directors can be issued deferred stock units from (i) an annual award; (ii) deferred compensation (in lieu of cash retainer, committee chair fees and lead director fees); and (iii) dividend equivalents earned on outstanding deferred compensation. The Company also has a Performance Share Awards Program established pursuant to the 2004 Incentive Plan and which continues pursuant to the 2014 Incentive Plan. Under the program, the Company may issue performance share awards to certain employees of the Company who hold positions of Vice President (or its equivalent) or above. The performance share awards provide the recipient the right to earn shares of the Company’s common stock based upon the Company’s attainment of certain performance goals and the recipient meeting certain years of service criteria. The performance goals for performance share awards are based on the Company’s adjusted return on equity over a three -year performance period. Vesting of performance shares is contingent upon the Company attaining the relevant performance period minimum threshold return on equity and the recipient meeting certain years of service criteria, generally three years for full vesting, subject to proration for certain termination conditions. If the performance period return on equity is below the minimum threshold, none of the performance shares will vest. If performance meets or exceeds the minimum performance threshold, a range of performance shares will vest ( 50% to 150% for awards granted in 2018, 2019 and 2020), depending on the actual return on equity attained. The fair value of restricted stock units, deferred stock units and performance shares is measured at the market price of the Company stock at date of grant. Under terms of the 2014 Incentive Plan, holders of deferred stock units and performance shares may receive dividend equivalents. The total fair value of shares that vested during the years ended December 31, 2019 , 2018 and 2017 was $130 million , $135 million and $166 million , respectively. A summary of restricted stock units, deferred stock units and performance share activity under the 2014 Incentive Plan and the legacy plans as of and for the year ended December 31, 2019 is as follows: Restricted and Deferred Stock Units Performance Shares Other Equity Instruments Number Weighted Average Grant-Date Fair Value Number Weighted Average Grant-Date Fair Value Nonvested, beginning of year 1,216,676 $ 122.34 684,889 $ 128.83 Granted 591,365 126.88 371,754 126.18 Vested (592,754 ) (1) 114.17 (365,743 ) (2) 118.78 Forfeited (77,626 ) 127.75 (27,625 ) 129.78 Performance-based adjustment — — 5,472 (3) 123.17 Nonvested, end of year 1,137,661 (4) $ 128.59 668,747 $ 132.76 ___________________________________________ (1) Represents awards for which the requisite service has been rendered. (2) Reflects the number of performance shares attributable to the performance goals attained over the completed performance period ( three years ) and for which service conditions have been met. (3) Represents the current year change in estimated performance shares to reflect the attainment of performance goals for the awards that were granted in each of the years 2017 through 2019 . (4) 95,953 shares of restricted common stock were also issued outside of the 2014 Incentive Plan in 2017 in connection with the acquisition of Simply Business, of which 41,997 shares remain unvested and are not included in this table. See note 9. In addition to the nonvested shares presented in the above table, there are related nonvested dividend equivalent shares. The number of nonvested dividend equivalent shares related to deferred stock units was 329 at the beginning of the year and 285 at the end of the year and the number of nonvested dividend equivalent shares related to performance shares was 24,876 at the beginning of the year and 22,359 at the end of the year. The dividend equivalent shares are subject to the same vesting terms as the deferred stock units and performance shares. On February 4, 2020, the Company, under the 2014 Incentive Plan, granted 911,291 common stock awards in the form of restricted stock units, deferred stock units and performance share awards to participating officers, non-employee directors and other key employees. The restricted stock units and deferred stock units totaled 540,881 shares while the performance share awards totaled 370,410 shares. The fair value per share attributable to the common stock awards on the date of grant was $132.58 . Share-Based Compensation Cost Recognition The amount of compensation cost for awards subject to a service condition is based on the number of shares expected to be issued and is recognized over the time period for which service is to be provided (requisite service period). Awards granted to retiree-eligible employees or to employees who become retiree-eligible before an award’s vesting date are considered to have met the requisite service condition. The compensation cost for awards subject to a performance condition is based upon the probable outcome of the performance condition, which on the grant date reflects an estimate of attaining 100% of the performance shares granted. The compensation cost reflects an estimated annual forfeiture rate from 3.5% to 4.5% over the requisite service period of the awards. That estimate is revised if subsequent information indicates that the actual number of instruments expected to vest is likely to differ from previous estimates. Compensation costs for awards are recognized on a straight-line basis over the requisite service period. For awards that have graded vesting terms, the compensation cost is recognized on a straight-line basis over the requisite service period for each separate vesting portion of the award as if the award was, in substance, multiple awards. The total compensation cost for all share-based incentive compensation awards recognized in earnings for the years ended December 31, 2019 , 2018 and 2017 was $142 million , $140 million and $136 million , respectively. Included in these amounts are compensation cost adjustments of $2 million , $3 million and $3 million , for the years ended December 31, 2019 , 2018 and 2017 , respectively, that reflected the cost associated with the updated estimate of performance shares due to attaining certain performance levels from the date of the initial grant of the performance awards. The related tax benefits recognized in earnings were $26 million , $26 million and $45 million for the years ended December 31, 2019 , 2018 and 2017 , respectively. At December 31, 2019 , there was $136 million of total unrecognized compensation cost related to all nonvested share-based incentive compensation awards. This includes stock options, restricted and deferred stock units and performance shares granted under the 2014 Incentive Plan and restricted common stock issued in connection with a 2017 business acquisition. The unrecognized compensation cost is expected to be recognized over a weighted-average period of 1.7 years . Cash received from the exercise of employee stock options under share-based compensation plans totaled $213 million , $132 million and $173 million in 2019 , 2018 and 2017 , respectively. The tax benefit for tax deductions from employee stock options exercised during 2019 , 2018 and 2017 totaled $18 million , $14 million and $31 million , respectively.

Pension Plans, Retirement Benef

Pension Plans, Retirement Benefits and Savings Plans	12 Months Ended
Pension Plans, Retirement Benefits and Savings Plans	Dec. 31, 2019
Retirement Benefits [Abstract]
Pension Plans, Retirement Benefits and Savings Plans	PENSION PLANS, RETIREMENT BENEFITS AND SAVINGS PLANS The Company sponsors a qualified non-contributory defined benefit pension plan (the qualified domestic pension plan), which covers substantially all U.S. domestic employees and provides benefits under a cash balance formula, except that certain limited groups of legacy participants are covered by a prior traditional final average pay formula. In addition, the Company sponsors a nonqualified defined benefit pension plan which covers certain highly-compensated employees, pension plans for employees of its foreign subsidiaries, and a postretirement health and life insurance benefit plan for employees satisfying certain age and service requirements and for certain retirees. Obligations and Funded Status The following tables summarize the funded status, obligations and amounts recognized in the consolidated balance sheet for the Company’s benefit plans. The Company uses a December 31 measurement date for its pension and postretirement benefit plans. (at and for the year ended December 31, in millions) Qualified Domestic Pension Plan Nonqualified and Foreign Pension Plans Total 2019 2018 2019 2018 2019 2018 Change in projected benefit obligation: Benefit obligation at beginning of year $ 3,444 $ 3,679 $ 215 $ 230 $ 3,659 $ 3,909 Benefits earned 112 126 6 7 118 133 Interest cost on benefit obligation 134 119 7 7 141 126 Actuarial (gain) loss 451 (273 ) 19 (11 ) 470 (284 ) Benefits paid (187 ) (207 ) (11 ) (12 ) (198 ) (219 ) Foreign currency exchange rate change — — 5 (6 ) 5 (6 ) Benefit obligation at end of year $ 3,954 $ 3,444 $ 241 $ 215 $ 4,195 $ 3,659 Change in plan assets: Fair value of plan assets at beginning of year $ 3,771 $ 3,957 $ 103 $ 113 $ 3,874 $ 4,070 Actual return on plan assets 686 (179 ) 10 (1 ) 696 (180 ) Company contributions — 200 8 10 8 210 Benefits paid (187 ) (207 ) (11 ) (12 ) (198 ) (219 ) Foreign currency exchange rate change — — 5 (7 ) 5 (7 ) Fair value of plan assets at end of year 4,270 3,771 115 103 4,385 3,874 Funded status of plan at end of year $ 316 $ 327 $ (126 ) $ (112 ) $ 190 $ 215 Amounts recognized in the consolidated balance sheet consist of: Accrued over-funded benefit plan assets $ 316 $ 327 $ 1 $ 4 $ 317 $ 331 Accrued under-funded benefit plan liabilities — — (127 ) (116 ) (127 ) (116 ) Total $ 316 $ 327 $ (126 ) $ (112 ) $ 190 $ 215 Amounts recognized in accumulated other comprehensive income consist of: Net actuarial loss $ 1,094 $ 1,113 $ 49 $ 36 $ 1,143 $ 1,149 Prior service cost (benefit) (3 ) (5 ) — 1 (3 ) (4 ) Total $ 1,091 $ 1,108 $ 49 $ 37 $ 1,140 $ 1,145 Postretirement Benefit Plans (at and for the year ended December 31, in millions) 2019 2018 Change in projected benefit obligation: Benefit obligation at beginning of year $ 203 $ 225 Benefits earned — — Interest cost on benefit obligation 7 7 Actuarial gain (31 ) (18 ) Benefits paid (9 ) (10 ) Foreign currency exchange rate change 1 (1 ) Benefit obligation at end of year $ 171 $ 203 Change in plan assets: Fair value of plan assets at beginning of year $ 12 $ 13 Actual return on plan assets 1 — Company contributions 8 9 Benefits paid (9 ) (10 ) Fair value of plan assets at end of year 12 12 Funded status of plan at end of year $ (159 ) $ (191 ) Amounts recognized in the consolidated balance sheet consist of: Accrued under-funded benefit plan liability $ (159 ) $ (191 ) Amounts recognized in accumulated other comprehensive income consist of: Net actuarial gain $ (49 ) $ (17 ) Prior service benefit (21 ) (25 ) Total $ (70 ) $ (42 ) The total accumulated benefit obligation for the Company’s defined benefit pension plans was $4.05 billion and $3.53 billion at December 31, 2019 and 2018 , respectively. The qualified domestic pension plan accounted for $3.82 billion and $3.32 billion of the total accumulated benefit obligation at December 31, 2019 and 2018 , respectively, whereas the nonqualified and foreign plans accounted for $0.23 billion and $0.21 billion of the total accumulated benefit obligation at December 31, 2019 and 2018 , respectively. For pension plans with a projected benefit obligation in excess of plan assets, the aggregate projected benefit obligation was $228 million and $203 million at December 31, 2019 and 2018 , respectively, and the aggregate plan assets were $100 million and $87 million at December 31, 2019 and 2018 , respectively. For pension plans with an accumulated benefit obligation in excess of plan assets, the aggregate accumulated benefit obligation was $218 million and $195 million at December 31, 2019 and 2018 , respectively, and the aggregate plan assets were $100 million and $87 million at December 31, 2019 and 2018 , respectively. For postretirement benefit plans with an accumulated benefit obligation in excess of plan assets, the aggregate accumulated benefit obligation was $171 million and $203 million at December 31, 2019 and 2018 , respectively, and the aggregate plan assets were $12 million at both December 31, 2019 and 2018 . The $451 million actuarial loss experienced in 2019 for the qualified domestic pension plan was largely driven by the decrease in the assumed discount rate from the prior year that was used to determine the projected benefit obligation at December 31, 2019. The $273 million actuarial gain experienced in 2018 for the qualified domestic pension plan was largely driven by the increase in the assumed discount rate from the prior year that was used to determine the projected benefit obligation at December 31, 2018. The Company has discretion regarding whether to provide additional funding and when to provide such funding to its qualified domestic pension plan. In 2019 , 2018 and 2017 , there were no required contributions to the qualified domestic pension plan. In 2019 , the Company made no voluntary contributions to the qualified domestic pension plan. In 2018 and 2017 , the Company voluntarily made contributions totaling $200 million and $300 million , respectively, to the qualified domestic pension plan. There is no required contribution to the qualified domestic pension plan during 2020 , and the Company has not determined whether or not additional funding will be made during 2020 . With respect to the Company’s foreign pension plans, there are no significant required contributions in 2020 . The following table summarizes the components of net periodic benefit cost and other amounts recognized in other comprehensive income related to the benefit plans. Pension Plans Postretirement Benefit Plans (for the year ended December 31, in millions) 2019 2018 2017 2019 2018 2017 Net Periodic Benefit Cost: Service cost $ 118 $ 133 $ 119 $ — $ — $ — Non-service cost: Interest cost on benefit obligation 141 126 127 7 7 7 Expected return on plan assets (275 ) (264 ) (240 ) (1 ) — — Settlement — — 3 — — — Amortization of unrecognized: Prior service benefit (1 ) (1 ) (1 ) (3 ) (4 ) (4 ) Net actuarial loss 56 91 85 — — — Total non-service cost (benefit) (79 ) (48 ) (26 ) 3 3 3 Net periodic benefit cost 39 85 93 3 3 3 Other Changes in Benefit Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income: Prior service benefit — — — — — — Net actuarial loss (gain) 49 160 40 (31 ) (18 ) 13 Foreign currency exchange rate change 1 (1 ) 2 — — (1 ) Settlement — — (2 ) — — — Amortization of prior service benefit 1 1 1 3 4 4 Amortization of net actuarial loss (56 ) (91 ) (85 ) — — — Total other changes recognized in other comprehensive income (5 ) 69 (44 ) (28 ) (14 ) 16 Total other changes recognized in net periodic benefit cost and other comprehensive income $ 34 $ 154 $ 49 $ (25 ) $ (11 ) $ 19 The following table indicates the line items in which the respective service costs and non-service cost (benefit) are presented in the consolidated statement of income for the years ended December 31, 2019 , 2018 and 2017 . Pension Plans Postretirement Benefit Plans (for the year ended December 31, in millions) 2019 2018 2017 2019 2018 2017 Service Cost: Net investment income $ 1 $ 1 $ — $ — $ — $ — Claims and claim adjustment expenses 48 54 48 — — — General and administrative expenses 69 78 71 — — — Total service cost 118 133 119 — — — Non-Service Cost (Benefit): Claims and claim adjustment expenses (33 ) (19 ) (11 ) 1 1 1 General and administrative expenses (46 ) (29 ) (15 ) 2 2 2 Total non-service cost (benefit) (79 ) (48 ) (26 ) 3 3 3 Net periodic benefit cost $ 39 $ 85 $ 93 $ 3 $ 3 $ 3 Assumptions The following table summarizes assumptions used with regard to the Company’s qualified and nonqualified domestic pension plans and the domestic postretirement benefit plans. (at and for the year ended December 31,) 2019 2018 Assumptions used to determine benefit obligations Discount rate: Qualified domestic pension plan 3.28 % 4.39 % Nonqualified domestic pension plan 3.17 % 4.33 % Domestic postretirement benefit plan 3.09 % 4.26 % Cash balance interest crediting rate 4.01 % 4.01 % Future compensation increase rate 4.00 % 4.00 % Assumptions used to determine net periodic benefit cost Discount rate: Qualified domestic pension plan: Service cost 4.57 % 3.87 % Interest cost 4.02 % 3.34 % Nonqualified domestic pension plan: Service cost 4.40 % 3.73 % Interest cost 3.95 % 3.26 % Domestic postretirement benefit plan: Interest cost 3.90 % 3.21 % Expected long-term rate of return on assets: Pension plan 7.00 % 7.00 % Postretirement benefit plan 4.00 % 4.00 % Assumed health care cost trend rates Following year: Medical (before age 65) 7.00 % 7.50 % Medical (age 65 and older) 8.25 % 8.75 % Rate to which the cost trend rate is assumed to decline (ultimate trend rate) 4.50 % 4.50 % Year that the rate reaches the ultimate trend rate: Medical (before age 65) 2026 2026 Medical (age 65 and older) 2026 2026 The discount rate assumption used to determine the benefit obligation is based on a yield-curve approach. Under this approach, individual spot rates from the yield curve of a hypothetical portfolio of high quality fixed maturity corporate bonds (rated Aa) available at the year-end valuation date, for which the timing and amount of cash outflows correspond with the timing and amount of the estimated benefit payouts of the Company’s benefit plan, are applied to expected future benefits payments in measuring the projected benefit obligation . The discount rate assumption used to determine benefit obligations disclosed above represents the weighted average of the individual spot rates. The discount rate assumption used to determine the net periodic benefit cost is the single weighted average discount rate derived from the yield curve used to measure the benefit obligation at the beginning of the year. In choosing the expected long-term rate of return on plan assets, the Company selected the rate that was set as the return objective by the Company’s Benefit Plans Investment Committee, which had considered the historical returns of equity and fixed maturity markets in conjunction with prevailing economic and financial market conditions. The assumptions made for the Company’s foreign pension and foreign postretirement benefit plans are not materially different from those of the Company’s qualified domestic pension plan and the domestic postretirement benefit plan. Plan Assets The qualified domestic pension plan assets are invested for the exclusive benefit of the plan participants and beneficiaries and are intended, over time, to satisfy the benefit obligations under the plan. Risk tolerance is established through consideration of plan liabilities, plan funded status and corporate financial position. The asset mix guidelines have been established and are reviewed quarterly. These guidelines are intended to serve as tools to facilitate the investment of plan assets to maximize long-term total return and the ongoing oversight of the plan’s investment performance. Investment risk is measured and monitored on an ongoing basis through daily and monthly investment portfolio reviews, annual liability measurements and periodic asset/liability studies. The Company’s overall investment strategy for the qualified domestic pension plan is to achieve a mix of approximately 85% to 90% of investments for long-term growth and 10% to 15% for near-term benefit payments with a diversification of asset types, fund strategies and fund managers. The current target allocations for plan assets are 55% to 65% equity securities and 20% to 40% fixed income securities, with the remainder allocated to short-term securities. Equity securities primarily include investments in large, medium and small-cap companies primarily located in the United States. Fixed income securities include corporate bonds of companies from diversified industries, mortgage-backed securities, U.S. Treasury securities and debt securities issued by foreign governments. Assets of the Company’s foreign pension plans are not significant. Fair Value Measurement — Pension Plans and Other Postretirement Benefit Assets For a discussion of the methods employed by the Company to measure the fair value of invested assets, see note 4. The following discussion of fair value measurements applies exclusively to the Company’s pension plans and other postretirement benefit assets. Fair value estimates for equity and bond mutual funds held by the pension plans reflect prices received from an external pricing service that are based on observable market transactions. These estimates are primarily included in Level 1. Short-term securities are carried at fair value which approximates cost plus accrued interest or amortized discount. The fair value or market value of these is periodically compared to this amortized cost and is based on significant observable inputs as determined by an external pricing service. Accordingly, the estimates of fair value for such short-term securities, other than U.S. Treasury securities and money market mutual funds, provided by an external pricing service are included in the amount disclosed in Level 2 of the hierarchy. The estimated fair value of U.S. Treasury securities and money market mutual funds is included in the amount disclosed in Level 1 as the estimates are based on unadjusted market prices. Fair Value Hierarchy — Pension Plans The following tables present the level within the fair value hierarchy at which the financial assets of the Company’s pension plans are measured on a recurring basis. (at December 31, 2019, in millions) Total Level 1 Level 2 Level 3 Invested assets: Fixed maturities Obligations of states, municipalities and political subdivisions $ 3 $ — $ 3 $ — Debt securities issued by foreign governments 30 — 30 — Mortgage-backed securities, collateralized mortgage obligations and pass-through securities 30 — 30 — All other corporate bonds 715 — 715 — Total fixed maturities 778 — 778 — Mutual funds Equity mutual funds 1,585 1,578 7 — Bond mutual funds 869 866 3 — Total mutual funds 2,454 2,444 10 — Equity securities 1,018 1,017 1 — Other investments 2 — — 2 Cash and short-term securities U.S. Treasury securities 20 20 — — Money market mutual funds 27 27 — — Other 86 17 69 — Total cash and short-term securities 133 64 69 — Total $ 4,385 $ 3,525 $ 858 $ 2 (at December 31, 2018, in millions) Total Level 1 Level 2 Level 3 Invested assets: Fixed maturities Obligations of states, municipalities and political subdivisions $ 3 $ — $ 3 $ — Debt securities issued by foreign governments 27 — 27 — Mortgage-backed securities, collateralized mortgage obligations and pass-through securities 30 — 30 — All other corporate bonds 712 — 712 — Total fixed maturities 772 — 772 — Mutual funds Equity mutual funds 1,288 1,282 6 — Bond mutual funds 760 757 3 — Total mutual funds 2,048 2,039 9 — Equity securities 783 783 — — Other investments 1 — — 1 Cash and short-term securities U.S. Treasury securities 30 30 — — Money market mutual funds — — — — Other 240 19 221 — Total cash and short-term securities 270 49 221 — Total $ 3,874 $ 2,871 $ 1,002 $ 1 Other Postretirement Benefit Plans The Company’s overall investment strategy is to achieve a mix of approximately 35% to 65% of investments for long-term growth and 35% to 65% for near-term insurance payments with a wide diversification of asset types, fund strategies and fund managers. The current target allocations for plan assets are 25% to 75% fixed income securities, with the remainder allocated to short-term securities. Fixed income securities include corporate bonds of companies from diversified industries, mortgage-backed securities and U.S. Treasuries. Fair Value — Other Postretirement Benefit Plans The Company’s other postretirement benefit plans had financial assets of $12 million at both December 31, 2019 and 2018 , which are measured at fair value on a recurring basis. The assets are primarily corporate bonds, which are categorized as level 2 in the fair value hierarchy. Estimated Future Benefit Payments The following table presents the estimated benefits expected to be paid by the Company’s pension and postretirement benefit plans for the next ten years (reflecting estimated future employee service). Benefits Expected to be Paid (in millions) Pension Plans Postretirement Benefit Plans 2020 $ 250 $ 12 2021 261 12 2022 265 12 2023 273 12 2024 276 12 2025 through 2029 1,400 55 Savings Plan The Company has a savings plan, The Travelers 401(k) Savings Plan (the Savings Plan), in which substantially all U.S. domestic Company employees are eligible to participate. Under the Savings Plan, the Company matches employee contributions up to 5% of eligible pay, with a maximum annual match of $6,500 which becomes 100% vested after three years of service. The Company’s matching contribution is made in cash and invested according to the employee’s current investment elections and can be reinvested into other investment options in accordance with the terms of the Savings Plan. The Company’s non-U.S. employees participate in separate savings plans. The total expense related to all of the savings plans was $123 million , $118 million and $119 million for the years ended December 31, 2019 , 2018 and 2017 , respectively. All common shares held by the Savings Plan are considered outstanding for basic and diluted EPS computations and dividends paid on all shares are charged to retained earnings.

Leases

Leases	12 Months Ended
Leases	Dec. 31, 2019
Leases [Abstract]
Leases	LEASES The Company enters into lease agreements for real estate that is primarily used for office space in the ordinary course of business. These leases are accounted for as operating leases, whereby lease expense is recognized on a straight-line basis over the term of the lease. See note 1—Adoption of Accounting Standards— Leases for additional information regarding the accounting for leases. Most leases include an option to extend or renew the lease term. The exercise of the renewal option is at the Company's discretion. The operating lease liability includes lease payments related to options to extend or renew the lease term if the Company is reasonably certain of exercising those options. The Company, in determining the present value of lease payments, utilizes either the rate implicit in the lease, if that rate is readily determinable, or the Company’s incremental secured borrowing rate commensurate with the term of the underlying lease. Lease expense is included in general and administrative expenses in the consolidated statement of income. Additional information regarding the Company’s real estate operating leases is as follows: (for the year ended December 31, in millions) 2019 Lease cost Operating leases $ 92 Short-term leases (1) 10 Lease expense 102 Less: sublease income (2) — Net lease cost $ 102 Other information on operating leases Cash payments to settle a lease liability reported in cash flows $ 104 Right-of-use assets obtained in exchange for new lease liabilities $ 60 Weighted average discount rate 3.02 % Weighted average remaining lease term in years 5.1 years _________________________________________________________ (1) Leases with an initial term of twelve months or less are not recorded on the balance sheet. (2) Sublease income consists of rent from third parties of office space and is recognized as part of other revenues in the consolidated statement of income. Lease expense was $185 million and $188 million , respectively, for the years ended December 31, 2018 and 2017 for real estate and other operating leases. The following table presents the contractual maturities of the Company's lease liabilities: (in millions) Real Estate Lease Liability 2020 $ 108 2021 93 2022 71 2023 51 2024 35 Thereafter 54 Total undiscounted lease payments 412 Less: present value adjustment 32 Operating lease liability $ 380

Contingencies, Commitments and

Contingencies, Commitments and Guarantees	12 Months Ended
Contingencies, Commitments and Guarantees	Dec. 31, 2019
Contingencies, Commitments and Guarantees [Abstract]
Contingencies, Commitments and Guarantees	CONTINGENCIES, COMMITMENTS AND GUARANTEES Contingencies The major pending legal proceedings, other than ordinary routine litigation incidental to the business, to which the Company or any of its subsidiaries is a party or to which any of the Company’s properties is subject are described below. Asbestos and Environmental Claims and Litigation In the ordinary course of its insurance business, the Company has received and continues to receive claims for insurance arising under policies issued by the Company asserting alleged injuries and damages from asbestos- and environmental-related exposures that are the subject of related coverage litigation. The Company is defending asbestos- and environmental-related litigation vigorously and believes that it has meritorious defenses; however, the outcomes of these disputes are uncertain. In this regard, the Company employs dedicated specialists and comprehensive resolution strategies to manage asbestos and environmental loss exposure, including settling litigation under appropriate circumstances. Currently, it is not possible to predict legal outcomes and their impact on future loss development for claims and litigation relating to asbestos and environmental claims. Any such development could be affected by future court decisions and interpretations, as well as future changes, if any, in applicable legislation. Because of these uncertainties, additional liabilities may arise for amounts in excess of the Company’s current insurance reserves. In addition, the Company’s estimate of ultimate claims and claim adjustment expenses may change. These additional liabilities or changes in estimates, or a range of either, cannot now be reasonably estimated and could result in income statement charges that could be material to the Company’s results of operations in future periods. Other Proceedings Not Arising Under Insurance Contracts or Reinsurance Agreements The Company is involved in other lawsuits, including lawsuits alleging extra-contractual damages relating to insurance contracts or reinsurance agreements, that do not arise under insurance contracts or reinsurance agreements. The legal costs associated with such lawsuits are expensed in the period in which the costs are incurred. Based upon currently available information, the Company does not believe it is reasonably possible that any such lawsuit or related lawsuits would be material to the Company’s results of operations or would have a material adverse effect on the Company’s financial position or liquidity. Other Commitments and Guarantees Commitments Investment Commitments — The Company has unfunded commitments to private equity limited partnerships and real estate partnerships in which it invests. These commitments totaled $1.66 billion and $1.60 billion at December 31, 2019 and 2018 , respectively. Guarantees In the ordinary course of selling businesses to third parties, the Company has agreed to indemnify purchasers for losses arising out of breaches of representations and warranties, obligations arising from certain liabilities and any breach or failure to perform certain covenants with respect to the businesses being sold. Such indemnification provisions generally are applicable from the closing date to the expiration of the relevant statutes of limitations, although, in some cases, there may be agreed upon term limitations or no term limitations. Certain of these contingent obligations are subject to deductibles which have to be incurred by the obligee before the Company is obligated to make payments. The maximum amount of the Company’s contingent obligation for indemnifications related to the sale of businesses that are quantifiable was $351 million at December 31, 2019 . The Company also has contingent obligations for guarantees related to certain investments, certain insurance policy obligations of former insurance subsidiaries and various other indemnifications. The Company also provides standard indemnifications to service providers in the normal course of business. The indemnification clauses are often standard contractual terms. The maximum amount of the Company’s obligation related to the guarantee of certain insurance policy obligations of a former insurance subsidiary was $480 million at December 31, 2019 , all of which is indemnified by a third party. Certain of the guarantees and indemnifications described above have no stated or notional amounts or limitation to the maximum potential future payments, and, accordingly, the Company is unable to provide an estimate of the maximum potential payments for such arrangements.

Noncash Investing and Financing

Noncash Investing and Financing Activities	12 Months Ended
Noncash Investing and Financing Activities	Dec. 31, 2019
Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract]
Noncash Investing and Financing Activities	NONCASH INVESTING AND FINANCING ACTIVITIES There were no material noncash financing or investing activities during the years ended December 31, 2019 , 2018 and 2017 .

Consolidating Financial Stateme

Consolidating Financial Statements	12 Months Ended
Consolidating Financial Statements	Dec. 31, 2019
Consolidating Financial Statements of The Travelers Companies, Inc. and Subsidiaries (Unaudited) disclosure
Consolidating Financial Statements of The Travelers Companies, Inc. and Subsidiaries (Unaudited)	CONSOLIDATING FINANCIAL STATEMENTS OF THE TRAVELERS COMPANIES, INC. AND SUBSIDIARIES The following consolidating financial statements of the Company have been prepared pursuant to Rule 3-10 of Regulation S-X. These consolidating financial statements have been prepared from the Company’s financial information on the same basis of accounting as the consolidated financial statements. The Travelers Companies, Inc. (excluding its subsidiaries, TRV) has fully and unconditionally guaranteed certain debt obligations of Travelers Property Casualty Corp. (TPC) and Travelers Insurance Group Holdings, Inc. (TIGHI), which totaled $700 million at December 31, 2019 . Prior to the merger of TPC and The St. Paul Companies, Inc. in 2004, TPC fully and unconditionally guaranteed the payment of all principal, premiums, if any, and interest on certain debt obligations of its wholly-owned subsidiary, TIGHI. Concurrent with the merger, TRV fully and unconditionally assumed such guarantee obligations of TPC. TPC is deemed to have no assets or operations independent of TIGHI. Consolidating financial information for TIGHI has not been presented herein because such financial information would be substantially the same as the financial information provided for TPC. CONSOLIDATING STATEMENT OF INCOME (Unaudited) For the year ended December 31, 2019 (in millions) TPC Other Subsidiaries TRV Eliminations Consolidated Revenues Premiums $ 19,362 $ 8,910 $ — $ — $ 28,272 Net investment income 1,730 697 41 — 2,468 Fee income 458 1 — — 459 Net realized investment gains (1) 44 36 33 — 113 Other revenues 142 127 — — 269 Total revenues 21,736 9,771 74 — 31,581 Claims and expenses Claims and claim adjustment expenses 12,926 6,207 — — 19,133 Amortization of deferred acquisition costs 3,095 1,506 — — 4,601 General and administrative expenses 2,973 1,371 21 — 4,365 Interest expense 47 — 297 — 344 Total claims and expenses 19,041 9,084 318 — 28,443 Income (loss) before income taxes 2,695 687 (244 ) — 3,138 Income tax expense (benefit) 483 110 (77 ) — 516 Net income of subsidiaries — — 2,789 (2,789 ) — Net income $ 2,212 $ 577 $ 2,622 $ (2,789 ) $ 2,622 ___________________________________________ (1) Total other-than-temporary impairments (OTTI) for the year ended December 31, 2019 , and the amounts comprising total OTTI that were recognized in net realized investment gains and in other comprehensive income (OCI), were as follows: (in millions) TPC Other Subsidiaries TRV Eliminations Consolidated Total OTTI losses $ (2 ) $ (1 ) $ — $ — $ (3 ) OTTI losses recognized in net realized investment gains $ (2 ) $ (2 ) $ — $ — $ (4 ) OTTI gains recognized in OCI $ — $ 1 $ — $ — $ 1 CONSOLIDATING STATEMENT OF INCOME (Unaudited) For the year ended December 31, 2018 (in millions) TPC Other Subsidiaries TRV Eliminations Consolidated Revenues Premiums $ 18,508 $ 8,551 $ — $ — $ 27,059 Net investment income 1,704 738 32 — 2,474 Fee income 432 — — — 432 Net realized investment gains (losses) (1) 118 9 (13 ) — 114 Other revenues 96 112 — (5 ) 203 Total revenues 20,858 9,410 19 (5 ) 30,282 Claims and expenses Claims and claim adjustment expenses 12,344 5,947 — — 18,291 Amortization of deferred acquisition costs 2,972 1,409 — — 4,381 General and administrative expenses 2,947 1,335 20 (5 ) 4,297 Interest expense 48 — 304 — 352 Total claims and expenses 18,311 8,691 324 (5 ) 27,321 Income (loss) before income taxes 2,547 719 (305 ) — 2,961 Income tax expense (benefit) 437 115 (114 ) — 438 Net income of subsidiaries — — 2,714 (2,714 ) — Net income $ 2,110 $ 604 $ 2,523 $ (2,714 ) $ 2,523 ___________________________________________ (1) Total other-than-temporary impairments (OTTI) for the year ended December 31, 2018 , and the amounts comprising total OTTI that were recognized in net realized investment gains (losses) and in other comprehensive income (OCI), were as follows: (in millions) TPC Other Subsidiaries TRV Eliminations Consolidated Total OTTI losses $ (1 ) $ — $ — $ — $ (1 ) OTTI losses recognized in net realized investment gains (losses) $ (1 ) $ — $ — $ — $ (1 ) OTTI losses recognized in OCI $ — $ — $ — $ — $ — CONSOLIDATING STATEMENT OF INCOME (Unaudited) For the year ended December 31, 2017 (in millions) TPC Other Subsidiaries TRV Eliminations Consolidated Revenues Premiums $ 17,562 $ 8,121 $ — $ — $ 25,683 Net investment income 1,627 759 24 (13 ) 2,397 Fee income 447 — — — 447 Net realized investment gains (1) 19 131 66 — 216 Other revenues 101 68 — (10 ) 159 Total revenues 19,756 9,079 90 (23 ) 28,902 Claims and expenses Claims and claim adjustment expenses 11,735 5,732 — — 17,467 Amortization of deferred acquisition costs 2,820 1,346 — — 4,166 General and administrative expenses 2,906 1,249 25 (10 ) 4,170 Interest expense 48 — 321 — 369 Total claims and expenses 17,509 8,327 346 (10 ) 26,172 Income (loss) before income taxes 2,247 752 (256 ) (13 ) 2,730 Income tax expense (benefit) 519 290 (130 ) (5 ) 674 Net income of subsidiaries — — 2,190 (2,190 ) — Net income $ 1,728 $ 462 $ 2,064 $ (2,198 ) $ 2,056 ___________________________________________ (1) Total other-than-temporary impairments (OTTI) for the year ended December 31, 2017 , and the amounts comprising total OTTI that were recognized in net realized investment gains and in other comprehensive income (OCI), were as follows: (in millions) TPC Other Subsidiaries TRV Eliminations Consolidated Total OTTI losses $ (4 ) $ (9 ) $ — $ — $ (13 ) OTTI losses recognized in net realized investment gains $ (5 ) $ (9 ) $ — $ — $ (14 ) OTTI gains recognized in OCI $ 1 $ — $ — $ — $ 1 CONSOLIDATING STATEMENT OF COMPREHENSIVE INCOME (Unaudited) For the year ended December 31, 2019 (in millions) TPC Other Subsidiaries TRV Eliminations Consolidated Net income $ 2,212 $ 577 $ 2,622 $ (2,789 ) $ 2,622 Other comprehensive income (loss): Changes in net unrealized gains on investment securities: Having no credit losses recognized in the consolidated statement of income 2,097 893 4 — 2,994 Having credit losses recognized in the consolidated statement of income (2 ) (2 ) — — (4 ) Net changes in benefit plan assets and obligations 1 (3 ) 35 — 33 Net changes in unrealized foreign currency translation 53 64 — — 117 Other comprehensive income before income taxes and other comprehensive income of subsidiaries 2,149 952 39 — 3,140 Income tax expense 441 188 12 — 641 Other comprehensive income, net of taxes, before other comprehensive income of subsidiaries 1,708 764 27 — 2,499 Other comprehensive income of subsidiaries — — 2,472 (2,472 ) — Other comprehensive income 1,708 764 2,499 (2,472 ) 2,499 Comprehensive income $ 3,920 $ 1,341 $ 5,121 $ (5,261 ) $ 5,121 CONSOLIDATING STATEMENT OF COMPREHENSIVE INCOME (Unaudited) For the year ended December 31, 2018 (in millions) TPC Other Subsidiaries TRV Eliminations Consolidated Net income $ 2,110 $ 604 $ 2,523 $ (2,714 ) $ 2,523 Other comprehensive loss: Changes in net unrealized gains on investment securities: Having no credit losses recognized in the consolidated statement of income (1,028 ) (461 ) — — (1,489 ) Having credit losses recognized in the consolidated statement of income (20 ) (7 ) — — (27 ) Net changes in benefit plan assets and obligations 1 (4 ) (53 ) — (56 ) Net changes in unrealized foreign currency translation (144 ) (103 ) — — (247 ) Other comprehensive loss before income taxes and other comprehensive loss of subsidiaries (1,191 ) (575 ) (53 ) — (1,819 ) Income tax benefit (231 ) (101 ) (17 ) — (349 ) Other comprehensive loss, net of taxes, before other comprehensive loss of subsidiaries (960 ) (474 ) (36 ) — (1,470 ) Other comprehensive loss of subsidiaries — — (1,434 ) 1,434 — Other comprehensive loss (960 ) (474 ) (1,470 ) 1,434 (1,470 ) Comprehensive income $ 1,150 $ 130 $ 1,053 $ (1,280 ) $ 1,053 CONSOLIDATING STATEMENT OF COMPREHENSIVE INCOME (Unaudited) For the year ended December 31, 2017 (in millions) TPC Other Subsidiaries TRV Eliminations Consolidated Net income $ 1,728 $ 462 $ 2,064 $ (2,198 ) $ 2,056 Other comprehensive income (loss): Changes in net unrealized gains on investment securities: Having no credit losses recognized in the consolidated statement of income 313 25 (44 ) — 294 Having credit losses recognized in the consolidated statement of income 6 2 — — 8 Net changes in benefit plan assets and obligations (1 ) 8 22 — 29 Net changes in unrealized foreign currency translation 83 108 — — 191 Other comprehensive income (loss) before income taxes and other comprehensive income of subsidiaries 401 143 (22 ) — 522 Income tax expense 98 10 2 — 110 Other comprehensive income (loss), net of taxes, before other comprehensive income of subsidiaries 303 133 (24 ) — 412 Other comprehensive income of subsidiaries — — 436 (436 ) — Other comprehensive income 303 133 412 (436 ) 412 Comprehensive income $ 2,031 $ 595 $ 2,476 $ (2,634 ) $ 2,468 CONSOLIDATING BALANCE SHEET (Unaudited) At December 31, 2019 (in millions) TPC Other Subsidiaries TRV Eliminations Consolidated Assets Fixed maturities, available for sale, at fair value (amortized cost $65,281) $ 46,805 $ 21,238 $ 91 $ — $ 68,134 Equity securities, at fair value (cost $376) 102 114 209 — 425 Real estate investments 1 962 — — 963 Short-term securities 2,793 760 1,390 — 4,943 Other investments 2,690 728 1 — 3,419 Total investments 52,391 23,802 1,691 — 77,884 Cash 207 287 — — 494 Investment income accrued 428 186 4 — 618 Premiums receivable 5,331 2,578 — — 7,909 Reinsurance recoverables 6,511 1,724 — — 8,235 Ceded unearned premiums 603 86 — — 689 Deferred acquisition costs 2,094 179 — — 2,273 Contractholder receivables 4,606 13 — — 4,619 Goodwill 2,584 1,386 — (9 ) 3,961 Other intangible assets 218 112 — — 330 Investment in subsidiaries — — 30,028 (30,028 ) — Other assets 2,360 419 331 — 3,110 Total assets $ 77,333 $ 30,772 $ 32,054 $ (30,037 ) $ 110,122 Liabilities Claims and claim adjustment expense reserves $ 35,568 $ 16,281 $ — $ — $ 51,849 Unearned premium reserves 10,144 4,460 — — 14,604 Contractholder payables 4,606 13 — — 4,619 Payables for reinsurance premiums 210 153 — — 363 Deferred taxes 272 (170 ) 35 — 137 Debt 693 — 5,865 — 6,558 Other liabilities 4,609 1,236 204 — 6,049 Total liabilities 56,102 21,973 6,104 — 84,179 Shareholders’ equity Common stock (1,750.0 shares authorized; 255.5 shares issued and outstanding) — 585 23,469 (585 ) 23,469 Additional paid-in capital 11,634 7,073 — (18,707 ) — Retained earnings 8,451 823 36,984 (9,281 ) 36,977 Accumulated other comprehensive income 1,146 318 640 (1,464 ) 640 Treasury stock, at cost (522.1 shares) — — (35,143 ) — (35,143 ) Total shareholders’ equity 21,231 8,799 25,950 (30,037 ) 25,943 Total liabilities and shareholders’ equity $ 77,333 $ 30,772 $ 32,054 $ (30,037 ) $ 110,122 CONSOLIDATING BALANCE SHEET (Unaudited) At December 31, 2018 (in millions) TPC Other Subsidiaries TRV Eliminations Consolidated Assets Fixed maturities, available for sale, at fair value (amortized cost $63,601) $ 43,683 $ 19,697 $ 84 $ — $ 63,464 Equity securities, at fair value (cost $382) 105 92 171 — 368 Real estate investments 2 902 — — 904 Short-term securities 1,855 759 1,371 — 3,985 Other investments 2,746 810 1 — 3,557 Total investments 48,391 22,260 1,627 — 72,278 Cash 181 192 — — 373 Investment income accrued 434 187 3 — 624 Premiums receivable 5,089 2,417 — — 7,506 Reinsurance recoverables 5,904 2,466 — — 8,370 Ceded unearned premiums 522 56 — — 578 Deferred acquisition costs 1,930 190 — — 2,120 Deferred taxes 167 302 (24 ) — 445 Contractholder receivables 3,867 918 — — 4,785 Goodwill 2,578 1,368 — (9 ) 3,937 Other intangible assets 224 121 — — 345 Investment in subsidiaries — — 26,993 (26,993 ) — Other assets 2,220 15 669 (32 ) 2,872 Total assets $ 71,507 $ 30,492 $ 29,268 $ (27,034 ) $ 104,233 Liabilities Claims and claim adjustment expense reserves $ 34,093 $ 16,575 $ — $ — $ 50,668 Unearned premium reserves 9,414 4,141 — — 13,555 Contractholder payables 3,867 918 — — 4,785 Payables for reinsurance premiums 169 120 — — 289 Debt 693 32 5,871 (32 ) 6,564 Other liabilities 4,133 849 496 — 5,478 Total liabilities 52,369 22,635 6,367 (32 ) 81,339 Shareholders’ equity Common stock (1,750.0 shares authorized; 263.7 shares issued and 263.6 shares outstanding) — 401 23,144 (401 ) 23,144 Additional paid-in capital 11,634 7,023 — (18,657 ) — Retained earnings 8,065 879 35,211 (8,951 ) 35,204 Accumulated other comprehensive loss (561 ) (446 ) (1,859 ) 1,007 (1,859 ) Treasury stock, at cost (510.9 shares) — — (33,595 ) — (33,595 ) Total shareholders’ equity 19,138 7,857 22,901 (27,002 ) 22,894 Total liabilities and shareholders’ equity $ 71,507 $ 30,492 $ 29,268 $ (27,034 ) $ 104,233 CONSOLIDATING STATEMENT OF CASH FLOWS (Unaudited) For the year ended December 31, 2019 (in millions) TPC Other Subsidiaries TRV Eliminations Consolidated Cash flows from operating activities Net income $ 2,212 $ 577 $ 2,622 $ (2,789 ) $ 2,622 Net adjustments to reconcile net income to net cash provided by operating activities 1,750 943 (408 ) 298 2,583 Net cash provided by operating activities 3,962 1,520 2,214 (2,491 ) 5,205 Cash flows from investing activities Proceeds from maturities of fixed maturities 4,727 2,107 11 — 6,845 Proceeds from sales of investments: Fixed maturities 1,295 891 1 — 2,187 Equity securities 53 75 12 — 140 Other investments 345 114 — — 459 Purchases of investments: Fixed maturities (7,011 ) (3,686 ) (14 ) — (10,711 ) Equity securities (2 ) (75 ) (17 ) — (94 ) Real estate investments — (107 ) — — (107 ) Other investments (424 ) (73 ) — — (497 ) Net sales (purchases) of short-term securities (939 ) 1 (19 ) — (957 ) Securities transactions in course of settlement 163 (4 ) (1 ) — 158 Other (317 ) (8 ) — — (325 ) Net cash used in investing activities (2,110 ) (765 ) (27 ) — (2,902 ) Cash flows from financing activities Treasury stock acquired — share repurchase authorization — — (1,500 ) — (1,500 ) Treasury stock acquired — net employee share-based compensation — — (48 ) — (48 ) Dividends paid to shareholders — — (844 ) — (844 ) Payment of debt — (32 ) (500 ) 32 (500 ) Issuance of debt — — 492 — 492 Issuance of common stock — employee share options — — 213 — 213 Dividends paid to parent company (1,827 ) (632 ) — 2,459 — Net cash used in financing activities (1,827 ) (664 ) (2,187 ) 2,491 (2,187 ) Effect of exchange rate changes on cash 1 4 — — 5 Net increase in cash 26 95 — — 121 Cash at beginning of year 181 192 — — 373 Cash at end of year $ 207 $ 287 $ — $ — $ 494 Supplemental disclosure of cash flow information Income taxes paid (received) $ 375 $ 131 $ (78 ) $ — $ 428 Interest paid $ 47 $ — $ 291 $ — $ 338 CONSOLIDATING STATEMENT OF CASH FLOWS (Unaudited) For the year ended December 31, 2018 (in millions) TPC Other Subsidiaries TRV Eliminations Consolidated Cash flows from operating activities Net income $ 2,110 $ 604 $ 2,523 $ (2,714 ) $ 2,523 Net adjustments to reconcile net income to net cash provided by operating activities 1,141 605 (363 ) 474 1,857 Net cash provided by operating activities 3,251 1,209 2,160 (2,240 ) 4,380 Cash flows from investing activities Proceeds from maturities of fixed maturities 5,158 1,906 22 — 7,086 Proceeds from sales of investments: Fixed maturities 2,449 1,096 1 — 3,546 Equity securities 65 107 6 — 178 Real estate investments 66 8 — — 74 Other investments 403 108 — — 511 Purchases of investments: Fixed maturities (9,404 ) (4,096 ) (26 ) — (13,526 ) Equity securities (8 ) (99 ) (10 ) — (117 ) Real estate investments (1 ) (73 ) — — (74 ) Other investments (454 ) (83 ) — — (537 ) Net sales (purchases) of short-term securities 895 154 (141 ) — 908 Securities transactions in course of settlement (80 ) 24 — — (56 ) Acquisition, net of cash acquired — (4 ) — — (4 ) Other (310 ) (8 ) — — (318 ) Net cash used in investing activities (1,221 ) (960 ) (148 ) — (2,329 ) Cash flows from financing activities Treasury stock acquired — share repurchase authorization — — (1,270 ) — (1,270 ) Treasury stock acquired — net employee share-based compensation — — (51 ) — (51 ) Dividends paid to shareholders — — (814 ) — (814 ) Payment of debt — — (600 ) — (600 ) Issuance of debt — 18 591 (18 ) 591 Issuance of common stock — employee share options — — 132 — 132 Dividends paid to parent company (2,003 ) (255 ) — 2,258 — Net cash used in financing activities (2,003 ) (237 ) (2,012 ) 2,240 (2,012 ) Effect of exchange rate changes on cash (3 ) (7 ) — — (10 ) Net increase in cash 24 5 — — 29 Cash at beginning of year 157 187 — — 344 Cash at end of year $ 181 $ 192 $ — $ — $ 373 Supplemental disclosure of cash flow information Income taxes paid (received) $ 437 $ 254 $ (283 ) $ — $ 408 Interest paid $ 47 $ — $ 300 $ — $ 347 CONSOLIDATING STATEMENT OF CASH FLOWS (Unaudited) For the year ended December 31, 2017 (in millions) TPC Other Subsidiaries TRV Eliminations Consolidated Cash flows from operating activities Net income $ 1,728 $ 462 $ 2,064 $ (2,198 ) $ 2,056 Net adjustments to reconcile net income to net cash provided by operating activities 1,500 701 (32 ) (77 ) 2,092 Net cash provided by operating activities 3,228 1,163 2,032 (2,275 ) 4,148 Cash flows from investing activities Proceeds from maturities of fixed maturities 6,576 2,168 6 — 8,750 Proceeds from sales of investments: Fixed maturities 1,007 846 1 — 1,854 Equity securities 97 414 254 — 765 Real estate investments — 23 — — 23 Other investments 357 124 — (13 ) 468 Purchases of investments: Fixed maturities (8,513 ) (3,697 ) (40 ) — (12,250 ) Equity securities (68 ) (133 ) (258 ) — (459 ) Real estate investments (1 ) (58 ) — — (59 ) Other investments (444 ) (97 ) — — (541 ) Net sales (purchases) of short-term securities (303 ) (120 ) 397 — (26 ) Securities transactions in course of settlement (55 ) 5 3 — (47 ) Acquisition, net of cash acquired — 25 (477 ) 13 (439 ) Other (244 ) 3 — — (241 ) Net cash used in investing activities (1,591 ) (497 ) (114 ) — (2,202 ) Cash flows from financing activities Treasury stock acquired — share repurchase authorization — — (1,378 ) — (1,378 ) Treasury stock acquired — net employee share-based compensation — — (62 ) — (62 ) Dividends paid to shareholders — — (785 ) — (785 ) Payment of debt — — (657 ) — (657 ) Issuance of debt — 14 789 (14 ) 789 Issuance of common stock — employee share options — — 173 — 173 Dividends paid to parent company (1,624 ) (665 ) — 2,289 — Net cash used in financing activities (1,624 ) (651 ) (1,920 ) 2,275 (1,920 ) Effect of exchange rate changes on cash 3 8 — — 11 Net increase (decrease) in cash 16 23 (2 ) — 37 Cash at beginning of year 141 164 2 — 307 Cash at end of year $ 157 $ 187 $ — $ — $ 344 Supplemental disclosure of cash flow information Income taxes paid (received) $ 481 $ 206 $ (173 ) $ — $ 514 Interest paid $ 47 $ — $ 320 $ — $ 367

Selected Quarterly Financial Da

Selected Quarterly Financial Data (Unaudited)	12 Months Ended
Selected Quarterly Financial Data (Unaudited)	Dec. 31, 2019
Quarterly Financial Information Disclosure [Abstract]
Selected Quarterly Financial Data (Unaudited)	SELECTED QUARTERLY FINANCIAL DATA (Unaudited) 2019 (in millions, except per share amounts) First Quarter Second Quarter Third Quarter Fourth Quarter Total Total revenues $ 7,671 $ 7,834 $ 8,013 $ 8,063 $ 31,581 Total expenses 6,704 7,169 7,581 6,989 28,443 Income before income taxes 967 665 432 1,074 3,138 Income tax expense 171 108 36 201 516 Net income $ 796 $ 557 $ 396 $ 873 $ 2,622 Net income per share (1) : Basic $ 3.01 $ 2.11 $ 1.52 $ 3.37 $ 10.01 Diluted 2.99 2.10 1.50 3.35 9.92 2018 (in millions, except per share amounts) First Second Third Fourth Total Total revenues $ 7,286 $ 7,477 $ 7,723 $ 7,796 $ 30,282 Total expenses 6,508 6,846 6,917 7,050 27,321 Income before income taxes 778 631 806 746 2,961 Income tax expense 109 107 97 125 438 Net income $ 669 $ 524 $ 709 $ 621 $ 2,523 Net income per share (1) : Basic $ 2.45 $ 1.93 $ 2.65 $ 2.33 $ 9.37 Diluted 2.42 1.92 2.62 2.32 9.28 ___________________________________________ (1) Due to the use of an average number of shares for each quarter, the sum of the quarterly earnings per share may not equal the total earnings per share for the full year.

Schedule II

Schedule II	12 Months Ended
Schedule II	Dec. 31, 2019
Condensed Financial Information Disclosure [Abstract]
Schedule II	THE TRAVELERS COMPANIES, INC. (Parent Company Only) CONDENSED FINANCIAL INFORMATION OF REGISTRANT (in millions) CONDENSED STATEMENT OF INCOME For the year ended December 31, 2019 2018 2017 Revenues Net investment income $ 41 $ 32 $ 24 Net realized investment gains (losses) (1) 33 (13 ) 66 Total revenues 74 19 90 Expenses Interest 297 304 321 Other 21 20 25 Total expenses 318 324 346 Loss before income taxes and net income of subsidiaries (244 ) (305 ) (256 ) Income tax benefit (77 ) (114 ) (130 ) Loss before net income of subsidiaries (167 ) (191 ) (126 ) Net income of subsidiaries 2,789 2,714 2,190 Net income $ 2,622 $ 2,523 $ 2,064 ___________________________________________ (1) The parent company had no other-than-temporary impairment gains or losses recognized in net realized investment gains (losses) or in other comprehensive income during the years ended December 31, 2019 , 2018 and 2017 . The condensed financial statements should be read in conjunction with the notes to the condensed financial information of the registrant, as well as the consolidated financial statements and notes thereto. See the Report of Independent Registered Public Accounting Firm. SCHEDULE II THE TRAVELERS COMPANIES, INC. (Parent Company Only) CONDENSED FINANCIAL INFORMATION OF REGISTRANT (in millions) CONDENSED STATEMENT OF COMPREHENSIVE INCOME For the year ended December 31, 2019 2018 2017 Net income $ 2,622 $ 2,523 $ 2,064 Other comprehensive income (loss)—parent company: Changes in net unrealized gains on investment securities having no credit losses recognized in the consolidated statement of income 4 — (44 ) Net changes in benefit plan assets and obligations 35 (53 ) 22 Other comprehensive income (loss) before income taxes and other comprehensive income (loss) of subsidiaries 39 (53 ) (22 ) Income tax expense (benefit) 12 (17 ) 2 Other comprehensive income (loss), net of taxes, before other comprehensive income (loss) of subsidiaries 27 (36 ) (24 ) Other comprehensive income (loss) of subsidiaries 2,472 (1,434 ) 436 Other comprehensive income (loss) 2,499 (1,470 ) 412 Comprehensive income $ 5,121 $ 1,053 $ 2,476 The condensed financial statements should be read in conjunction with the notes to the condensed financial information of the registrant, as well as the consolidated financial statements and notes thereto. See the Report of Independent Registered Public Accounting Firm. SCHEDULE II THE TRAVELERS COMPANIES, INC. (Parent Company Only) CONDENSED FINANCIAL INFORMATION OF REGISTRANT (in millions) CONDENSED BALANCE SHEET At December 31, 2019 2018 Assets Fixed maturities $ 91 $ 84 Equity securities 209 171 Short-term securities 1,390 1,371 Investment in subsidiaries 30,028 26,993 Other assets 336 649 Total assets $ 32,054 $ 29,268 Liabilities Debt $ 5,865 $ 5,871 Other liabilities 239 496 Total liabilities 6,104 6,367 Shareholders’ equity Common stock (1,750.0 shares authorized; 255.5 and 263.7 shares issued, 255.5 and 263.6 shares outstanding) 23,469 23,144 Retained earnings 36,984 35,211 Accumulated other comprehensive income (loss) 640 (1,859 ) Treasury stock, at cost (522.1 and 510.9 shares) (35,143 ) (33,595 ) Total shareholders’ equity 25,950 22,901 Total liabilities and shareholders’ equity $ 32,054 $ 29,268 The condensed financial statements should be read in conjunction with the notes to the condensed financial information of the registrant, as well as the consolidated financial statements and notes thereto. See the Report of Independent Registered Public Accounting Firm. SCHEDULE II THE TRAVELERS COMPANIES, INC. (Parent Company Only) CONDENSED FINANCIAL INFORMATION OF REGISTRANT (in millions) CONDENSED STATEMENT OF CASH FLOWS For the year ended December 31, 2019 2018 2017 Cash flows from operating activities Net income $ 2,622 $ 2,523 $ 2,064 Adjustments to reconcile net income to net cash provided by operating activities: Equity in net income of subsidiaries (2,789 ) (2,714 ) (2,190 ) Dividends received from consolidated subsidiaries 2,459 2,258 2,289 Deferred federal income tax expense (benefit) (2 ) 28 40 Change in income taxes payable 3 100 3 Other (79 ) (35 ) (174 ) Net cash provided by operating activities 2,214 2,160 2,032 Cash flows from investing activities Net sales (purchases) of short-term securities (19 ) (141 ) 397 Other investments, net (8 ) (7 ) (34 ) Acquisition, net of cash acquired — — (477 ) Net cash used in investing activities (27 ) (148 ) (114 ) Cash flows from financing activities Treasury stock acquired—share repurchase authorization (1,500 ) (1,270 ) (1,378 ) Treasury stock acquired—net employee share-based compensation (48 ) (51 ) (62 ) Dividends paid to shareholders (844 ) (814 ) (785 ) Payment of debt (500 ) (600 ) (657 ) Issuance of debt 492 591 789 Issuance of common stock—employee share options 213 132 173 Net cash used in financing activities (2,187 ) (2,012 ) (1,920 ) Net decrease in cash — — (2 ) Cash at beginning of year — — 2 Cash at end of year $ — $ — $ — Supplemental disclosure of cash flow information Cash received during the year for taxes $ 78 $ 283 $ 173 Cash paid during the year for interest $ 291 $ 300 $ 320 The condensed financial statements should be read in conjunction with the notes to the condensed financial information of the registrant, as well as the consolidated financial statements and notes thereto. See the Report of Independent Registered Public Accounting Firm. SCHEDULE II THE TRAVELERS COMPANIES, INC. (Parent Company Only) NOTES TO THE CONDENSED FINANCIAL INFORMATION OF REGISTRANT 1. GUARANTEES The Travelers Companies, Inc. (TRV) fully and unconditionally guarantees the payment of all principal, premiums, if any, and interest on certain debt obligations of its subsidiaries TPC and TIGHI. The guarantees pertain to the $200 million 7.75% notes due 2026 and the $500 million 6.375% notes due 2033. TRV also has contingent obligations for guarantees in connection with the selling of businesses to third parties, certain insurance obligations of a subsidiary and various indemnifications including indemnifications to service providers in the normal course of business. The guarantees and indemnification clauses are often standard contractual terms and include indemnifications for breaches of representations and warranties and in some cases obligations arising from certain liabilities. The terms of these provisions vary in duration and nature.

Schedule III

Schedule III	12 Months Ended
Schedule III	Dec. 31, 2019
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Abstract]
Schedule III	THE TRAVELERS COMPANIES, INC. AND SUBSIDIARIES Supplementary Insurance Information 2017-2019 (in millions) Segment Deferred Acquisition Costs Claims and Claim Adjustment Expense Reserves Unearned Premiums Earned Premiums Net Investment Income (1) Claims and Claim Adjustment Expenses Amortization of Deferred Acquisition Costs Other Operating Expenses (2) Net Written Premiums 2019 Business Insurance $ 1,161 $ 42,252 $ 7,540 $ 15,300 $ 1,816 $ 10,963 $ 2,503 $ 2,627 $ 15,629 Bond & Specialty Insurance 309 3,316 1,845 2,565 233 1,094 478 483 2,739 Personal Insurance 803 6,268 5,219 10,407 419 7,076 1,620 1,220 10,783 Total—Reportable Segments 2,273 51,836 14,604 28,272 2,468 19,133 4,601 4,330 29,151 Other — 13 — — — — — 379 — Consolidated $ 2,273 $ 51,849 $ 14,604 $ 28,272 $ 2,468 $ 19,133 $ 4,601 $ 4,709 $ 29,151 2018 Business Insurance $ 1,102 $ 41,132 $ 7,112 $ 14,722 $ 1,833 $ 10,171 $ 2,388 $ 2,623 $ 14,956 Bond & Specialty Insurance 277 3,255 1,619 2,420 233 772 454 459 2,528 Personal Insurance 741 6,266 4,824 9,917 408 7,348 1,539 1,185 10,224 Total—Reportable Segments 2,120 50,653 13,555 27,059 2,474 18,291 4,381 4,267 27,708 Other — 15 — — — — — 382 — Consolidated $ 2,120 $ 50,668 $ 13,555 $ 27,059 $ 2,474 $ 18,291 $ 4,381 $ 4,649 $ 27,708 2017 Business Insurance $ 1,060 $ 40,352 $ 6,857 $ 14,146 $ 1,786 $ 9,521 $ 2,286 $ 2,563 $ 14,270 Bond & Specialty Insurance 258 3,421 1,515 2,307 228 899 432 464 2,359 Personal Insurance 707 5,860 4,543 9,230 383 7,047 1,448 1,111 9,590 Total—Reportable Segments 2,025 49,633 12,915 25,683 2,397 17,467 4,166 4,138 26,219 Other — 17 — — — — — 401 — Consolidated $ 2,025 $ 49,650 $ 12,915 $ 25,683 $ 2,397 $ 17,467 $ 4,166 $ 4,539 $ 26,219 ___________________________________________ (1) See note 2 of notes to the consolidated financial statements for discussion of the method used to allocate net investment income and invested assets to the identified segments. (2) Expense allocations are determined in accordance with prescribed statutory accounting practices. These practices make a reasonable allocation of all expenses to those product lines with which they are associated. See the Report of Independent Registered Public Accounting Firm.

Schedule V

Schedule V	12 Months Ended
Schedule V	Dec. 31, 2019
SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]
Schedule V	THE TRAVELERS COMPANIES, INC. AND SUBSIDIARIES Valuation and Qualifying Accounts (in millions) Balance at beginning of period Charged to costs and expenses Charged to other accounts Deductions (1) Balance at end of period 2019 Reinsurance recoverables $ 110 $ — $ — $ 18 $ 92 Allowance for uncollectible: Premiums receivable from underwriting activities $ 54 $ 59 $ — $ 58 $ 55 Deductibles $ 24 $ (2 ) $ — $ — $ 22 2018 Reinsurance recoverables $ 111 $ — $ — $ 1 $ 110 Allowance for uncollectible: Premiums receivable from underwriting activities $ 58 $ 50 $ — $ 54 $ 54 Deductibles $ 26 $ (1 ) $ — $ 1 $ 24 2017 Reinsurance recoverables $ 116 $ — $ — $ 5 $ 111 Allowance for uncollectible: Premiums receivable from underwriting activities $ 61 $ 38 $ — $ 41 $ 58 Deductibles $ 34 $ (2 ) $ — $ 6 $ 26 ___________________________________________ (1) Credited to the related asset account. See the Report of Independent Registered Public Accounting Firm.

Schedule VI

Schedule VI	12 Months Ended
Schedule VI	Dec. 31, 2019
SEC Schedule, 12-18, Supplemental Information, Property-Casualty Insurance Underwriters [Abstract]
Schedule VI	THE TRAVELERS COMPANIES, INC. AND SUBSIDIARIES Supplementary Information Concerning Property-Casualty Insurance Operations (1) 2017-2019 (in millions) Claims and Claim Adjustment Expenses Incurred Related to: Amortization of Deferred Acquisition Costs Paid Claims and Claim Adjustment Expenses Affiliation with Registrant(2) Deferred Acquisition Costs Claims and Claim Adjustment Expense Reserves Discount From Reserves for Unpaid Claims(3) Unearned Premiums Earned Premiums Net Investment Income Current Year Prior Year Net Written Premiums 2019 $ 2,273 $ 51,836 $ 1,155 $ 14,604 $ 28,272 $ 2,468 $ 18,854 $ 164 $ 4,601 $ 17,794 $ 29,151 2018 $ 2,120 $ 50,653 $ 1,158 $ 13,555 $ 27,059 $ 2,474 $ 18,614 $ (406 ) $ 4,381 $ 17,060 $ 27,708 2017 $ 2,025 $ 49,633 $ 1,102 $ 12,915 $ 25,683 $ 2,397 $ 17,846 $ (458 ) $ 4,166 $ 16,043 $ 26,219 ___________________________________________ (1) Excludes accident and health insurance business. (2) Consolidated property-casualty insurance operations. (3) For a discussion of types of reserves discounted and discount rates used, see note 7 of notes to the consolidated financial statements. See the Report of Independent Registered Public Accounting Firm.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
Summary of Significant Accounting Policies (Policies)	Dec. 31, 2019
Accounting Policies [Abstract]
Basis of Presentation [Policy Text Block]	Basis of Presentation The consolidated financial statements include the accounts of The Travelers Companies, Inc. (together with its subsidiaries, the Company). The preparation of the consolidated financial statements in conformity with U.S. generally accepted accounting principles (GAAP) requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and claims and expenses during the reporting period. Actual results could differ from those estimates. All material intercompany transactions and balances have been eliminated.
Adoption of Accounting Standards [Policy Text Block]	Adoption of Accounting Standards Financial Instruments: Recognition and Measurement of Financial Assets and Financial Liabilities In January 2016, the Financial Accounting Standards Board (FASB) issued updated guidance to address the recognition, measurement, presentation and disclosure of certain financial instruments. The updated guidance requires equity investments, except those accounted for under the equity method of accounting, that have readily determinable fair value to be measured at fair value with any changes in fair value recognized in net income. Equity securities that do not have readily determinable fair values may be measured at estimated fair value or cost less impairment, if any, adjusted for subsequent observable price changes, with changes in the carrying value recognized in net income. The updated guidance was effective for the quarter ended March 31, 2018 and early application of certain of the provisions in the updated guidance was allowed. The Company adopted the updated guidance for the quarter ended March 31, 2018 and elected to report changes in the fair value of equity investments in net realized investment gains (losses). The adoption of this guidance resulted in the recognition of $22 million of net after-tax unrealized gains on equity investments as a cumulative effect adjustment that increased retained earnings as of January 1, 2018 and decreased accumulated other comprehensive income (AOCI) by the same amount. At December 31, 2017, equity investments were classified as available-for-sale on the Company's balance sheet. However, upon adoption, the updated guidance eliminated the available-for-sale balance sheet classification for equity investments. Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income In February 2018, the FASB issued updated guidance that allows a reclassification from AOCI to retained earnings of the stranded tax effects that occurred due to the enactment of the Tax Cuts and Jobs Act of 2017 (TCJA). The updated guidance was effective for the quarter ended March 31, 2019, with early adoption allowed, and was required to be applied retrospectively to each period in which there are items impacted by the TCJA remaining in AOCI or at the beginning of the period of adoption. The Company adopted the updated guidance for the quarter ended March 31, 2019 and elected to reclassify the income tax effects of the TCJA from AOCI to retained earnings as of January 1, 2018. This reclassification resulted in an increase in retained earnings of $24 million as of January 1, 2018 and a decrease in AOCI by the same amount. Leases In February 2016, the FASB issued updated guidance on the accounting for leases that requires lessees to recognize a right-to-use asset and a lease liability for leases with terms of more than 12 months and retains the two classifications of a lease as either an operating or finance lease (previously referred to as a capital lease). The updated guidance was effective for reporting periods beginning after December 15, 2018 and required that the earliest comparative period presented include the measurement and recognition of existing leases with an adjustment to equity as if the updated guidance had always been applied. Alternatively, an entity may elect to recognize a cumulative effect adjustment to the the opening balance of retained earnings in the year of adoption. Early adoption was permitted. The Company adopted the updated guidance for leases for the quarter ended March 31, 2019 and elected to utilize a cumulative-effect adjustment to the opening balance of retained earnings for the year of adoption. Accordingly, the Company’s reporting for the comparative periods prior to adoption continue to be presented in the financial statements in accordance with previous lease accounting guidance. The Company also elected to apply all practical expedients applicable to the Company in the updated guidance for transition for leases in effect at adoption, including using hindsight to determine the lease term of existing leases, the option to not reassess whether an existing contract is a lease or contains a lease and whether the lease is an operating or finance lease. The adoption of the updated guidance resulted in the Company recognizing a right-of-use asset of $320 million as part of other assets and a lease liability of $384 million as part of other liabilities in the consolidated balance sheet, as well as de-recognizing the liability for deferred rent that was required under the previous guidance, for its corporate real estate agreements at March 31, 2019. The cumulative effect adjustment to the opening balance of retained earnings at January 1, 2019 was zero . The adoption of the updated guidance did not have a material effect on the Company’s results of operations or liquidity. Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract In August 2018, the FASB issued updated guidance on a customer's accounting for the implementation, set-up, and other upfront costs incurred in a cloud computing arrangement that is hosted by the vendor, i.e. a service contract. The updated guidance is effective for the quarter ending March 31, 2020, with early adoption permitted. The updated guidance requires an entity to determine the stage of a project that the implementation activity relates to and the nature of the associated costs in order to determine whether those costs should be expensed as incurred or capitalized. The updated guidance also requires the entity to amortize the capitalized implementation costs as an expense over the term of the hosting arrangement. The Company elected to adopt the guidance for the quarter ended March 31, 2019 and applied the guidance prospectively. The adoption of the updated guidance did not have a material effect on the Company’s results of operations, financial position or liquidity. Revenue from Contracts with Customers In May 2014, the FASB issued updated guidance to clarify the principles for recognizing revenue. The updated guidance was effective for the quarter ended March 31, 2018 and required an entity to recognize revenue as performance obligations are met, in order to reflect the transfer of goods or services to customers in an amount that reflects the consideration the entity is entitled to receive for those goods or services. For the year ended December 31, 2018 , approximately $171 million , or less than 1% of the Company's total revenues, were within the scope of this updated guidance and were generated from the services described below. While insurance contracts are not within the scope of this updated guidance, the Company’s revenue related to certain services with no underlying insurance risk is subject to the updated guidance. These services include the following: (i) insurance-related services, such as risk management services, claims administration, loss control and risk management information services on behalf of non-insureds; (ii) servicing carrier fees for various residual market pools and associations; and (iii) administrative fees related to servicing third-party insurers’ obligations to participate in the Workers' Compensation Residual Market Plans in certain states. The adoption of the updated guidance did not have a material impact on the Company's revenues. These revenues are earned as the Company completes its performance obligations, which primarily occurs on a pro rata basis over the contract service period and reported in fee income in the Company’s consolidated statement of income. Commissions earned from on-line insurance brokerage services are also subject to this updated guidance and there was not a material impact on these commissions from the adoption of the updated guidance. Commissions are generally earned upon collection of the gross premium in accordance with the contracts and an accrual is made to recognize policy cancellations, either at the policyholder’s direction or for non-payment. Commissions are reported in other revenues in the Company's consolidated statement of income. The Company does not capitalize the costs to obtain or fulfill the contracts for which revenues are reported in fee income and other revenues and has not recognized any material impairment losses on the receivables related to these contracts. The Company adopted the updated guidance for the quarter ended March 31, 2018. The adoption did not have a material effect on the Company’s results of operations, financial position or liquidity.
Investments [Policy Text Block]	Investments Fixed Maturities Fixed maturities include bonds, notes and redeemable preferred stocks. Fixed maturities, including instruments subject to securities lending agreements, are classified as available for sale and reported at fair value, with unrealized investment gains and losses, net of income taxes, charged or credited directly to other comprehensive income. Equity Securities Equity securities, which include public common and non-redeemable preferred stocks, are reported at fair value with changes in fair value recognized in net income. Prior to January 1, 2018, equity securities were classified as available for sale and changes in their fair value were charged or credited directly to other comprehensive income. Real Estate Investments The Company’s real estate investments include warehouses, office buildings and other commercial land and properties that are directly owned. Real estate is recorded on the purchase date at the purchase price, which generally represents fair value, and is supported by internal analysis or external appraisals that use discounted cash flow analyses and other acceptable valuation techniques. Real estate held for investment purposes is subsequently carried at cost less accumulated depreciation. Buildings are depreciated on a straight-line basis over the shorter of the expected useful life of the building or 39 years . Real estate held for sale is carried at lower of cost or fair value, less estimated costs to sell. Short-term Securities Short-term securities have an original maturity of less than one year and are carried at amortized cost, which approximates fair value. Other Investments Investments in Private Equity Limited Partnerships, Hedge Funds and Real Estate Partnerships The Company uses the equity method of accounting for investments in private equity limited partnerships, hedge funds and real estate partnerships. The partnerships and the hedge funds generally report investments on their balance sheet at fair value. The financial statements prepared by the investee are received by the Company on a lag basis, with the lag period generally dependent upon the type of underlying investments. The private equity and real estate partnerships provide financial information quarterly which is generally available to investors, including the Company, within three months following the date of the reporting period. The hedge funds provide financial information monthly, which is generally available to investors within one month following the date of the reporting period. The Company regularly requests financial information from the partnerships prior to the receipt of the partnerships’ financial statements and records any material information obtained from these requests in its consolidated financial statements. Other Also included in other investments are non-public common equities, preferred equities and derivatives. Non-public common equities and preferred equities are reported at fair value with changes in fair value recognized in net income. Prior to January 1, 2018, non-public common equities and preferred equities were reported at fair value with changes in fair value, net of taxes, charged or credited directly to other comprehensive income. The Company’s derivative financial instruments are carried at fair value, with the changes in fair value reflected in the consolidated statement of income in net realized investment gains (losses). For a further discussion of the derivatives used by the Company, see note 3.
Net Investment Income [Policy Text Block]	Net Investment Income Investment income from fixed maturities is recognized based on the constant effective yield method which includes an adjustment for estimated principal pre-payments, if any. The effective yield used to determine amortization for fixed maturities subject to prepayment risk (e.g., asset-backed, loan-backed and structured securities) is recalculated and adjusted periodically based upon actual historical and/or projected future cash flows, which are obtained from a widely-accepted securities data provider. The adjustments to the yield for highly rated prepayable fixed maturities are accounted for using the retrospective method. The adjustments to the yield for non-highly rated prepayable fixed maturities are accounted for using the prospective method. Dividends on equity securities (including those with transfer restrictions) are recognized in income when declared. Rental income on real estate is recognized on a straight-line basis over the lease term. See the section titled: Real Estate in note 3 for further discussion. Investments in private equity limited partnerships, hedge funds, real estate partnerships and joint ventures are accounted for using the equity method of accounting, whereby the Company’s share of the investee’s earnings or losses in the fund is reported in net investment income. Accrual of income is suspended on non-securitized fixed maturities that are in default, or on which it is likely that future payments will not be made as scheduled. Interest income on investments in default is recognized only when payments are received. Investments included in the consolidated balance sheet that were not income-producing for the preceding 12 months were not material. For fixed maturities where the Company records an other-than-temporary impairment, a determination is made as to the cause of the impairment and whether the Company expects a recovery in the value. For fixed maturities where the Company expects a recovery in value, not necessarily to par, the constant effective yield method is utilized, and the investment is amortized to the expected recovery amount.
Investment Gains and Losses [Policy Text Block]	Investment Gains and Losses Net realized investment gains and losses are included as a component of pre-tax revenues based upon specific identification of the investments sold on the trade date. Included in net realized investment gains (losses) are other-than-temporary impairment losses on invested assets other than those investments accounted for using the equity method of accounting as described in the “Investment Impairments” section that follows.
Investment Impairments [Policy Text Block]	Investment Impairments The Company conducts a periodic review to identify and evaluate invested assets having other-than-temporary impairments. Other-Than-Temporary Impairments of Fixed Maturities Some of the factors considered in identifying other-than-temporary impairments of fixed maturities include: (1) the extent to which the fair value has been less than amortized cost; (2) the financial condition, near-term and long-term prospects for the issuer, including the relevant industry conditions and trends, and implications of rating agency actions and offering prices; (3) the likelihood of the recoverability of principal and interest; (4) whether it is more likely than not that the Company will be required to sell the investment prior to an anticipated recovery in value; and (5) the length of time and extent to which the fair value has been less than amortized cost. For fixed maturity investments that the Company does not intend to sell or for which it is more likely than not that the Company would not be required to sell before an anticipated recovery in value, the Company separates the credit loss component of the impairment from the amount related to all other factors and reports the credit loss component in net realized investment gains (losses). The impairment related to all other factors is reported in other comprehensive income. For fixed maturity investments the Company intends to sell or for which it is more likely than not that the Company will be required to sell before an anticipated recovery in value, the full amount of the impairment is included in net realized investment gains (losses). Upon recognizing an other-than-temporary impairment, the new cost basis of the investment is the previous amortized cost basis less the other-than-temporary impairment recognized in net realized investment gains (losses). The new cost basis is not adjusted for any subsequent recoveries in fair value; however, for fixed maturity investments the difference between the new cost basis and the expected cash flows is accreted on a quarterly basis to net investment income over the remaining expected life of the investment. Determination of Credit Loss — Fixed Maturities The Company determines the credit loss component of fixed maturity investments by utilizing discounted cash flow modeling to determine the present value of the security and comparing the present value with the amortized cost of the security. If the amortized cost is greater than the present value of the expected cash flows, the difference is considered a credit loss and recognized in net realized investment gains (losses). For non-structured fixed maturities (U.S. Treasury securities, obligations of U.S. government and government agencies and authorities, obligations of states, municipalities and political subdivisions, debt securities issued by foreign governments and certain corporate debt), the estimate of expected cash flows is determined by projecting a recovery value and a recovery time frame and assessing whether further principal and interest will be received. The determination of recovery value incorporates an issuer valuation assumption utilizing one or a combination of valuation methods as deemed appropriate by the Company. The Company determines the undiscounted recovery value by allocating the estimated value of the issuer to the Company’s assessment of the priority of claims. The present value of the cash flows is determined by applying the effective yield of the security at the date of acquisition (or the most recent implied rate used to accrete the security if the implied rate has changed as a result of a previous impairment) and an estimated recovery time frame. Generally, that time frame for securities for which the issuer is in bankruptcy is 12 months . For securities for which the issuer is financially troubled but not in bankruptcy, that time frame is generally 24 months . Included in the present value calculation are expected principal and interest payments; however, for securities for which the issuer is classified as bankrupt or in default, the present value calculation assumes no interest payments and a single recovery amount. In estimating the recovery value, significant judgment is involved in the development of assumptions relating to a myriad of factors related to the issuer including, but not limited to, revenue, margin and earnings projections, the likely market or liquidation values of assets, potential additional debt to be incurred pre- or post-bankruptcy/restructuring, the ability to shift existing or new debt to different priority layers, the amount of restructuring/bankruptcy expenses, the size and priority of unfunded pension obligations, litigation or other contingent claims, the treatment of intercompany claims and the likely outcome with respect to inter-creditor conflicts. For structured fixed maturity securities (primarily residential and commercial mortgage-backed securities and asset-backed securities), the Company estimates the present value of the security by projecting future cash flows of the assets underlying the securitization, allocating the flows to the various tranches based on the structure of the securitization and determining the present value of the cash flows using the effective yield of the security at the date of acquisition (or the most recent implied rate used to accrete the security if the implied rate has changed as a result of a previous impairment or changes in expected cash flows). The Company incorporates levels of delinquencies, defaults and severities as well as credit attributes of the remaining assets in the securitization, along with other economic data, to arrive at its estimate of the parameters applied to the assets underlying the securitization. Real Estate Investments On at least an annual basis, the Company obtains independent appraisals for substantially all of its real estate investments. In addition, the carrying value of all real estate investments is reviewed for impairment on a quarterly basis or when events or changes in circumstances indicate that the carrying amount may not be recoverable. The review for impairment considers the valuation from the independent appraisal, when applicable, and incorporates an estimate of the undiscounted cash flows expected to result from the use and eventual disposition of the real estate property. An impairment loss is recognized if the expected future undiscounted cash flows are less than the carrying value of the real estate property. The impairment loss is the amount by which the carrying amount exceeds fair value. Other Investments The Company reviews its investments in private equity limited partnerships, hedge funds and real estate partnerships for impairment no less frequently than quarterly and monitors the performance throughout the year through discussions with the managers/general partners. If the Company becomes aware of an impairment of a partnership’s investments at the balance sheet date prior to receiving the partnership’s financial statements, it will recognize an impairment by recording a reduction in the carrying value of the partnership with a corresponding charge to net investment income. Changes in Intent to Sell Temporarily Impaired Assets The Company may, from time to time, sell invested assets subsequent to the balance sheet date that it did not intend to sell at the balance sheet date. Conversely, the Company may not sell invested assets that it asserted that it intended to sell at the balance sheet date. Such changes in intent are due to events occurring subsequent to the balance sheet date. The types of events that may result in a change in intent include, but are not limited to, significant changes in the economic facts and circumstances related to the invested asset (e.g., a downgrade or upgrade from a rating agency), significant unforeseen changes in liquidity needs, or changes in tax laws or the regulatory environment.
Securities Lending [Policy Text Block]	Securities Lending The Company has, from time to time, engaged in securities lending activities from which it generates net investment income by lending certain of its investments to other institutions for short periods of time. Borrowers of these securities provide collateral equal to at least 102% of the market value of the loaned securities plus accrued interest. This collateral is held by a third-party custodian, and the Company has the right to access the collateral only in the event that the institution borrowing the Company’s securities is in default under the lending agreement (i.e., the Company is not permitted to re-pledge or sell any such collateral). Therefore, the Company does not recognize the receipt of the collateral held by the third-party custodian or the obligation to return the collateral. The loaned securities remain a recorded asset of the Company. The Company accepts only cash as collateral for securities on loan and restricts the manner in which that cash is invested.
Reinsurance Recoverables [Policy Text Block]	Reinsurance Recoverables Amounts recoverable from reinsurers are estimated in a manner consistent with the associated claim liability. The Company reports its reinsurance recoverables net of an allowance for estimated uncollectible reinsurance recoverables. The allowance is based upon the Company’s ongoing review of amounts outstanding, length of collection periods, changes in reinsurer credit standing, disputes, applicable coverage defenses and other relevant factors. Amounts deemed to be uncollectible, including amounts due from known insolvent reinsurers, are written off against the allowance for estimated uncollectible reinsurance recoverables. Any subsequent collections of amounts previously written off are reported as part of claims and claim adjustment expenses. The Company evaluates and monitors the financial condition of its reinsurers under voluntary reinsurance arrangements to minimize its exposure to significant losses from reinsurer insolvencies.
Deferred Acquisition Costs [Policy Text Block]	Deferred Acquisition Costs Incremental direct costs of acquired, new and renewal insurance contracts, consisting of commissions (other than contingent commissions) and premium-related taxes, are capitalized and charged to expense pro rata over the contract periods in which the related premiums are earned. Deferred acquisition costs are reviewed to determine if they are recoverable from future income and, if not, are charged to expense. Future investment income attributable to related premiums is taken into account in measuring the recoverability of the carrying value of this asset. All other acquisition expenses are charged to operations as incurred.
Contractholder Receivables and Payables [Policy Text Block]	Contractholder Receivables and Payables Under certain workers’ compensation insurance contracts with deductible features, the Company is obligated to pay the claimant for the full amount of the claim. The Company is subsequently reimbursed by the policyholder for the deductible amount. These amounts are included on a gross basis in the consolidated balance sheet in contractholder payables and contractholder receivables, respectively.
Goodwill and Intangible Assets [Policy Text Block]	Goodwill and Other Intangible Assets The Company performs a review, on at least an annual basis, of goodwill held by the reporting units which are the Company’s three operating and reportable segments: Business Insurance; Bond & Specialty Insurance; and Personal Insurance. The Company estimates the fair value of its reporting units and compares it to their carrying value, including goodwill. If the carrying values of the reporting units were to exceed their fair value, the amount of the impairment would be calculated and goodwill adjusted accordingly. The Company uses a discounted cash flow model to estimate the fair value of its reporting units. The discounted cash flow model is an income approach to valuation that is based on a detailed cash flow analysis for deriving a current fair value of reporting units and is representative of the Company’s reporting units’ current and expected future financial performance. The discount rate assumptions reflect the Company’s assessment of the risks inherent in the projected future cash flows and the Company’s weighted-average cost of capital, and are compared against available market data for reasonableness. Other indefinite-lived intangible assets held by the Company are also reviewed for impairment on at least an annual basis. The classification of the asset as indefinite-lived is reassessed and an impairment is recognized if the carrying amount of the asset exceeds its fair value. Intangible assets that are deemed to have a finite useful life are amortized over their useful lives. The carrying amount of intangible assets with a finite useful life is regularly reviewed for indicators of impairment in value. Impairment is recognized only if the carrying amount of the intangible asset is not recoverable from its undiscounted cash flows and is measured as the difference between the carrying amount and the fair value of the asset. As a result of the reviews performed for the years ended December 31, 2019 , 2018 and 2017 , the Company determined that the estimated fair value substantially exceeded the respective carrying value of its reporting units for those years and that goodwill was not impaired. The Company also determined during its reviews for each year that its other indefinite-lived intangible assets and finite-lived intangible assets were not impaired.
Claims and Claims Adjustment Expense Reserves [Policy Text Block]	Claims and Claim Adjustment Expense Reserves Claims and claim adjustment expense reserves represent management's estimate of the ultimate liability for unpaid losses and loss adjustment expenses for claims that have been reported and claims that have been incurred but not yet reported (IBNR) as of the balance sheet date. The reserves are adjusted regularly based upon experience. Included in the claims and claim adjustment expense reserves in the consolidated balance sheet are reserves for long-term disability and annuity claim payments, primarily arising from workers’ compensation insurance and workers’ compensation excess insurance policies, that are discounted to the present value of estimated future payments. The Company performs a continuing review of its claims and claim adjustment expense reserves, including its reserving techniques and the impact of reinsurance. The reserves are also reviewed regularly by qualified actuaries employed by the Company. Since the reserves are based on estimates, the ultimate liability may be more or less than such reserves. The effects of changes in such estimated reserves are included in the results of operations in the period in which the estimates are changed. Such changes in estimates could occur in a future period and may be material to the Company’s results of operations and financial position in such period.
Other Liabilities [Policy Text Block]	Other Liabilities Included in other liabilities in the consolidated balance sheet is the Company’s estimate of its liability for guaranty fund and other insurance-related assessments. The liability for expected state guaranty fund and other premium-based assessments is recognized as the Company writes or becomes obligated to write or renew the premiums on which the assessments are expected to be based. The liability for loss-based assessments is recognized as the related losses are incurred. At December 31, 2019 and 2018 , the Company had a liability of $184 million and $217 million , respectively, for guaranty fund and other insurance-related assessments and related recoverables of $13 million and $16 million , respectively. The liability for such assessments and the related recoverables are not discounted for the time value of money. The loss-based assessments are expected to be paid over a period ranging from one year to the life expectancy of certain workers’ compensation claimants and the recoveries are expected to occur over the same period of time. Also included in other liabilities is an accrual for policyholder dividends. Certain insurance contracts, primarily workers’ compensation, are participating whereby dividends are paid to policyholders in accordance with contract provisions. Net written premiums for participating dividend policies were approximately 1% of total net written premiums for each of the years ended December 31, 2019 , 2018 and 2017 . Policyholder dividends are accrued against earnings using best available estimates of amounts to be paid. The liability accrued for policyholder dividends totaled $71 million and $72 million at December 31, 2019 and 2018 , respectively.
Treasury Stock [Policy Text Block]	Treasury Stock The cost of common stock repurchased by the Company is reported as treasury stock and represents authorized and unissued shares of the Company under the Minnesota Business Corporation Act.
Statutory Accounting Practices [Policy Text Block]	Statutory Accounting Practices The Company’s U.S. insurance subsidiaries, domiciled principally in the State of Connecticut, are required to prepare statutory financial statements in accordance with the accounting practices prescribed or permitted by the insurance departments of the states of domicile. Prescribed statutory accounting practices are those practices that are incorporated directly or by reference in state laws, regulations, and general administrative rules applicable to all insurance enterprises domiciled in a particular state. The State of Connecticut requires insurers domiciled in Connecticut to prepare their statutory financial statements in accordance with National Association of Insurance Commissioners’ (NAIC) statutory accounting practices. Permitted statutory accounting practices are those practices that differ either from state-prescribed statutory accounting practices or NAIC statutory accounting practices. The Company does not apply any statutory accounting practices that would be considered a prescribed or permitted statutory accounting practice that differs from NAIC statutory accounting practices. The Company’s non-U.S. insurance subsidiaries file financial statements prepared in accordance with the regulatory reporting requirements of their respective local jurisdiction.
Premiums and Unearned Premium Reserves [Policy Text Block]	Premiums and Unearned Premium Reserves Premiums are recognized as revenues pro rata over the policy period. Unearned premium reserves represent the unexpired portion of policy premiums. Accrued retrospective premiums are included in premium balances receivable. Premium balances receivable are reported net of an allowance for estimated uncollectible premium amounts. Ceded premiums are charged to income over the applicable term of the various reinsurance contracts with third party reinsurers. Prepaid reinsurance premiums represent the unexpired portion of premiums ceded to reinsurers and are reported as part of other assets.
Fee Income [Policy Text Block]	Fee Income Fee income includes servicing carrier fees and revenues from large deductible policies and service contracts and is recognized as the Company completes its performance obligations, which is primarily on a pro rata basis over the contract service period or the underlying policy periods.
Other Revenues [Policy Text Block]	Other Revenues Other revenues include revenues from premium installment charges, which are recognized as collected, revenues of noninsurance subsidiaries other than fee income and gains and losses on dispositions of assets and redemption of debt, and other miscellaneous revenues, including gains recognized as a result of settlements of reinsurance disputes and claims-related legal matters.
Income Taxes [Policy Text Block]	Income Taxes The Company recognizes deferred income tax assets and liabilities for the expected future tax effects attributable to temporary differences between the financial statement and tax return bases of assets and liabilities, based on enacted tax rates and other provisions of the tax law. The effect of a change in tax laws or rates on deferred tax assets and liabilities is recognized in income in the period in which such change is enacted. Deferred tax assets are reduced by a valuation allowance if it is more likely than not that all or some portion of the deferred tax assets will not be realized.
Foreign Currency Translation [Policy Text Block]	Foreign Currency Translation The Company assigns functional currencies to its foreign operations, which are generally the currencies of the local operating environment. Foreign currency amounts are remeasured to the functional currency, and the resulting foreign exchange gains or losses are reflected in earnings. Functional currency amounts are then translated into U.S. dollars. The foreign currency remeasurement and translation are calculated using current exchange rates for items reported in the balance sheets and average exchange rates for items recorded in earnings. The change in unrealized foreign currency translation gain or loss during the year, net of tax, is a component of other comprehensive income.
Share-based Compensation [Policy Text Block]	Share-Based Compensation The Company has an employee stock incentive compensation plan that permits grants of nonqualified stock options, incentive stock options, stock appreciation rights, restricted stock, deferred stock, stock units, performance awards and other share-based or share-denominated awards with respect to the Company’s common stock. Compensation cost is measured based on the grant-date fair value of an award , utilizing the assumptions discussed in note 13. Compensation cost is recognized for financial reporting purposes over the period in which the employee is required to provide service in exchange for the award (generally the vesting period). In connection with certain share-based awards, participants are entitled to receive dividends during the vesting period, either in cash or dividend equivalent shares, commensurate with the dividends paid to common shareholders. Dividends and dividend equivalent shares on awards that are expected to vest are recorded in retained earnings. Dividends paid on awards that are not expected to vest as part of the Company’s forfeiture estimate are recorded as compensation expense.

Segment Information (Tables)

Segment Information (Tables)	12 Months Ended
Segment Information (Tables)	Dec. 31, 2019
Segment Reporting [Abstract]
Company's revenues and income by segment [Table Text Block]	(for the year ended December 31, in millions) Business Insurance Bond & Specialty Insurance Personal Insurance Total Reportable Segments 2019 Premiums $ 15,300 $ 2,565 $ 10,407 $ 28,272 Net investment income 1,816 233 419 2,468 Fee income 437 — 22 459 Other revenues 155 26 87 268 Total segment revenues (1) $ 17,708 $ 2,824 $ 10,935 $ 31,467 Amortization and depreciation $ 3,037 $ 533 $ 1,787 $ 5,357 Income tax expense 223 151 195 569 Segment income (1) 1,392 618 824 2,834 2018 Premiums $ 14,722 $ 2,420 $ 9,917 $ 27,059 Net investment income 1,833 233 408 2,474 Fee income 412 — 20 432 Other revenues 112 23 66 201 Total segment revenues (1) $ 17,079 $ 2,676 $ 10,411 $ 30,166 Amortization and depreciation $ 2,943 $ 515 $ 1,719 $ 5,177 Income tax expense 259 198 42 499 Segment income (1) 1,638 793 297 2,728 2017 Premiums $ 14,146 $ 2,307 $ 9,230 $ 25,683 Net investment income 1,786 228 383 2,397 Fee income 430 — 17 447 Other revenues 69 24 60 153 Total segment revenues (1) $ 16,431 $ 2,559 $ 9,690 $ 28,680 Amortization and depreciation $ 2,852 $ 493 $ 1,627 $ 4,972 Income tax expense (benefit) 448 208 (44 ) 612 Segment income (1) 1,613 556 128 2,297 _________________________________________ (1) Segment revenues for reportable business segments exclude net realized investment gains. Segment income for reportable business segments equals net income excluding the after-tax impact of net realized investment gains and, in 2017, the impact of the Tax Cuts and Jobs Act of 2017 at enactment.
Net written premiums by market [Table Text Block]	Net written premiums by market were as follows: (for the year ended December 31, in millions) 2019 2018 2017 Business Insurance: Domestic: Select Accounts $ 2,911 $ 2,828 $ 2,800 Middle Market 8,630 8,214 7,756 National Accounts 1,051 1,025 1,010 National Property and Other 1,965 1,805 1,691 Total Domestic 14,557 13,872 13,257 International 1,072 1,084 1,013 Total Business Insurance 15,629 14,956 14,270 Bond & Specialty Insurance: Domestic: Management Liability 1,605 1,455 1,367 Surety 866 835 793 Total Domestic 2,471 2,290 2,160 International 268 238 199 Total Bond & Specialty Insurance 2,739 2,528 2,359 Personal Insurance: Domestic: Agency: Automobile 5,124 4,972 4,646 Homeowners and Other 4,540 4,148 3,933 Total Agency 9,664 9,120 8,579 Direct-to-Consumer 412 396 361 Total Domestic 10,076 9,516 8,940 International 707 708 650 Total Personal Insurance 10,783 10,224 9,590 Total consolidated net written premiums $ 29,151 $ 27,708 $ 26,219
Business segment reconciliations of revenue and income, net of tax [Table Text Block]	(for the year ended December 31, in millions) 2019 2018 2017 Revenue reconciliation Earned premiums Business Insurance: Domestic: Workers’ compensation $ 3,829 $ 3,899 $ 3,962 Commercial automobile 2,632 2,388 2,132 Commercial property 1,937 1,828 1,775 General liability 2,342 2,181 2,047 Commercial multi-peril 3,453 3,333 3,198 Other 40 28 29 Total Domestic 14,233 13,657 13,143 International 1,067 1,065 1,003 Total Business Insurance 15,300 14,722 14,146 Bond & Specialty Insurance: Domestic: Fidelity and surety 1,036 1,017 977 General liability 1,082 1,004 962 Other 216 195 187 Total Domestic 2,334 2,216 2,126 International 231 204 181 Total Bond & Specialty Insurance 2,565 2,420 2,307 Personal Insurance: Domestic Automobile 5,311 5,097 4,655 Homeowners and Other 4,393 4,135 3,943 Total Domestic 9,704 9,232 8,598 International 703 685 632 Total Personal Insurance 10,407 9,917 9,230 Total earned premiums 28,272 27,059 25,683 Net investment income 2,468 2,474 2,397 Fee income 459 432 447 Other revenues 268 201 153 Total segment revenues 31,467 30,166 28,680 Other revenues 1 2 6 Net realized investment gains 113 114 216 Total revenues $ 31,581 $ 30,282 $ 28,902 Income reconciliation, net of tax Total segment income $ 2,834 $ 2,728 $ 2,297 Interest Expense and Other (1) (297 ) (298 ) (254 ) Core income 2,537 2,430 2,043 Net realized investment gains 85 93 142 Impact of Tax Cuts and Jobs Act of 2017 at enactment — — (129 ) Net income $ 2,622 $ 2,523 $ 2,056 ________________________________________ (1) The primary component of Interest Expense and Other was after-tax interest expense of $272 million , $278 million and $240 million in 2019 , 2018 and 2017 , respectively.
Asset reconciliation [Table Text Block]	(at December 31, in millions) 2019 2018 Asset reconciliation: Business Insurance $ 83,896 $ 78,965 Bond & Specialty Insurance 8,599 8,693 Personal Insurance 17,015 15,943 Total assets for reportable segments 109,510 103,601 Other assets (1) 612 632 Total consolidated assets $ 110,122 $ 104,233 ___________________________________________ (1) The primary components of other assets at both December 31, 2019 and 2018, were accrued over-funded benefit plan assets related to the Company's qualified domestic pension plan and other intangible assets.
Revenues of the Company's operations based on location [Table Text Block]	The following table presents revenues of the Company’s operations based on location: (for the year ended December 31, in millions) 2019 2018 2017 U.S. $ 29,638 $ 28,418 $ 27,253 Non-U.S.: Canada 1,371 1,293 1,232 Other Non-U.S. 572 571 417 Total Non-U.S. 1,943 1,864 1,649 Total revenues $ 31,581 $ 30,282 $ 28,902

Investments (Tables)

Investments (Tables)	12 Months Ended
Investments (Tables)	Dec. 31, 2019
Investments [Abstract]
Amortized cost and fair value of investments in fixed maturities [Table Text Block]	The amortized cost and fair value of investments in fixed maturities classified as available for sale were as follows: Amortized Gross Unrealized Fair (at December 31, 2019, in millions) Cost Gains Losses Value U.S. Treasury securities and obligations of U.S. government and government agencies and authorities $ 2,076 $ 19 $ — $ 2,095 Obligations of states, municipalities and political subdivisions: Local general obligation 15,490 829 4 16,315 Revenue 9,731 586 2 10,315 State general obligation 1,167 64 — 1,231 Pre-refunded 1,968 88 — 2,056 Total obligations of states, municipalities and political subdivisions 28,356 1,567 6 29,917 Debt securities issued by foreign governments 1,167 8 2 1,173 Mortgage-backed securities, collateralized mortgage obligations and pass-through securities 3,192 91 3 3,280 All other corporate bonds 30,442 1,195 18 31,619 Redeemable preferred stock 48 2 — 50 Total $ 65,281 $ 2,882 $ 29 $ 68,134 Amortized Gross Unrealized Fair (at December 31, 2018, in millions) Cost Gains Losses Value U.S. Treasury securities and obligations of U.S. government and government agencies and authorities $ 2,076 $ 4 $ 16 $ 2,064 Obligations of states, municipalities and political subdivisions: Local general obligation 14,473 219 120 14,572 Revenue 9,755 172 74 9,853 State general obligation 1,329 18 13 1,334 Pre-refunded 2,772 80 — 2,852 Total obligations of states, municipalities and political subdivisions 28,329 489 207 28,611 Debt securities issued by foreign governments 1,255 7 5 1,257 Mortgage-backed securities, collateralized mortgage obligations and pass-through securities 2,557 54 38 2,573 All other corporate bonds 29,307 156 583 28,880 Redeemable preferred stock 77 2 — 79 Total $ 63,601 $ 712 $ 849 $ 63,464
Amortized cost and fair value of fixed maturities by contractual maturity [Table Text Block]	The amortized cost and fair value of fixed maturities by contractual maturity follow. Actual maturities will differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without call or prepayment penalties. (at December 31, 2019, in millions) Amortized Cost Fair Value Due in one year or less $ 3,738 $ 3,760 Due after 1 year through 5 years 17,729 18,241 Due after 5 years through 10 years 17,262 18,215 Due after 10 years 23,360 24,638 62,089 64,854 Mortgage-backed securities, collateralized mortgage obligations and pass-through securities 3,192 3,280 Total $ 65,281 $ 68,134
Cost and fair value of investments in equity securities [Table Text Block]	The cost and fair value of investments in equity securities were as follows: (at December 31, 2019, in millions) Cost Gross Gains Gross Losses Fair Value Public common stock $ 341 $ 45 $ 3 $ 383 Non-redeemable preferred stock 35 7 — 42 Total $ 376 $ 52 $ 3 $ 425 (at December 31, 2018, in millions) Cost Gross Gains Gross Losses Fair Value Public common stock $ 338 $ 2 $ 24 $ 316 Non-redeemable preferred stock 44 8 — 52 Total $ 382 $ 10 $ 24 $ 368
Unrealized investment losses [Table Text Block]	The following tables summarize, for all investments in an unrealized loss position at December 31, 2019 and 2018 , the aggregate fair value and gross unrealized loss by length of time those securities have been continuously in an unrealized loss position. The fair value amounts reported in the tables are estimates that are prepared using the process described in note 4. The Company also relies upon estimates of several factors in its review and evaluation of individual investments, using the process described in note 1, in determining whether such investments are other-than-temporarily impaired. Less than 12 months 12 months or longer Total (at December 31, 2019, in millions) Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses Fixed maturities U.S. Treasury securities and obligations of U.S. government and government agencies and authorities $ 5 $ — $ 193 $ — $ 198 $ — Obligations of states, municipalities and political subdivisions 668 6 12 — 680 6 Debt securities issued by foreign governments 257 1 147 1 404 2 Mortgage-backed securities, collateralized mortgage obligations and pass-through securities 399 2 131 1 530 3 All other corporate bonds 1,571 10 662 8 2,233 18 Total fixed maturities $ 2,900 $ 19 $ 1,145 $ 10 $ 4,045 $ 29 Less than 12 months 12 months or longer Total (at December 31, 2018, in millions) Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses Fixed maturities U.S. Treasury securities and obligations of U.S. government and government agencies and authorities $ 484 $ 5 $ 1,011 $ 11 $ 1,495 $ 16 Obligations of states, municipalities and political subdivisions 5,241 82 3,298 125 8,539 207 Debt securities issued by foreign governments 96 — 328 5 424 5 Mortgage-backed securities, collateralized mortgage obligations and pass-through securities 593 9 1,070 29 1,663 38 All other corporate bonds 12,622 303 6,872 280 19,494 583 Total fixed maturities $ 19,036 $ 399 $ 12,579 $ 450 $ 31,615 $ 849
Impairment charges included in net realized investment gains [Table Text Block]	Impairment charges included in net realized investment gains in the consolidated statement of income were as follows: (for the year ended December 31, in millions) 2019 2018 2017 Fixed maturities U.S. Treasury securities and obligations of U.S. government and government agencies and authorities $ — $ — $ — Obligations of states, municipalities and political subdivisions — — — Debt securities issued by foreign governments — — — Mortgage-backed securities, collateralized mortgage obligations and pass-through securities — — — All other corporate bonds 4 1 4 Redeemable preferred stock — — — Total fixed maturities 4 1 4 Equity securities Public common stock — — 9 Non-redeemable preferred stock — — — Total equity securities — — 9 Other investments — — 1 Total $ 4 $ 1 $ 14
Cumulative amount of and the changes during the year in the credit losses of other-than-temporary impairments (OTTI) on fixed maturities recognized [Table Text Block]	The following tables present the cumulative amount of, and the changes during the year in, credit losses on fixed maturities held at December 31, 2019 and 2018 , that were recognized in the consolidated statement of income from other-than-temporary impairments (OTTI) and for which a portion of the OTTI was recognized in other comprehensive income (loss) in the consolidated balance sheet. Year ended December 31, 2019 (in millions) Cumulative OTTI Credit Losses Recognized for Securities Held, Beginning of Period Additions for OTTI Securities Where No Credit Losses Were Previously Recognized Additions for OTTI Securities Where Credit Losses Have Been Previously Recognized Reductions Due to Sales/Defaults of Credit- Impaired Securities Adjustments to Book Value of Credit- Impaired Securities due to Changes in Cash Flows Cumulative OTTI Credit Losses Recognized for Securities Still Held, End of Period Fixed maturities Mortgage-backed securities, collateralized mortgage obligations and pass-through securities $ 15 $ — $ — $ (9 ) $ 3 $ 9 All other corporate bonds 42 — — (49 ) 10 3 Total fixed maturities $ 57 $ — $ — $ (58 ) $ 13 $ 12 Year ended December 31, 2018 (in millions) Cumulative OTTI Credit Losses Recognized for Securities Held, Beginning of Period Additions for OTTI Securities Where No Credit Losses Were Previously Recognized Additions for OTTI Securities Where Credit Losses Have Been Previously Recognized Reductions Due to Sales/Defaults of Credit- Impaired Securities Adjustments to Book Value of Credit- Impaired Securities due to Changes in Cash Flows Cumulative OTTI Credit Losses Recognized for Securities Still Held, End of Period Fixed maturities Mortgage-backed securities, collateralized mortgage obligations and pass-through securities $ 29 $ — $ — $ (18 ) $ 4 $ 15 All other corporate bonds 46 — — (12 ) 8 42 Total fixed maturities $ 75 $ — $ — $ (30 ) $ 12 $ 57
Net investment income [Table Text Block]	(for the year ended December 31, in millions) 2019 2018 2017 Gross investment income Fixed maturities $ 2,070 $ 1,980 $ 1,895 Equity securities 15 16 28 Short-term securities 105 92 62 Real estate investments 55 48 44 Other investments 263 377 406 Gross investment income 2,508 2,513 2,435 Investment expenses 40 39 38 Net investment income $ 2,468 $ 2,474 $ 2,397
Change in net unrealized investments gains [Table Text Block]	Changes in net unrealized gains (losses) on investment securities that are included as a separate component of other comprehensive income (loss) were as follows: (at and for the year ended December 31, in millions) 2019 2018 2017 Changes in net unrealized investment gains (losses) Fixed maturities $ 2,990 $ (1,515 ) $ 513 Equity securities — — (215 ) Other investments — (1 ) 4 Change in net pre-tax unrealized gains (losses) on investment securities 2,990 (1,516 ) 302 Related tax expense (benefit) 631 (319 ) 78 Change in net unrealized gains (losses) on investment securities 2,359 (1,197 ) 224 Cumulative effect of adoption of updated accounting guidance for equity financial instruments at January 1, 2018 — (22 ) — Reclassification of certain tax effects from accumulated other comprehensive income at January 1, 2018 — 152 — Balance, beginning of year (113 ) 954 730 Balance, end of year $ 2,246 $ (113 ) $ 954

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
Fair Value Measurements (Tables)	Dec. 31, 2019
Fair Value Disclosures [Abstract]
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities reported at fair value are measured on a recurring basis [Table Text Block]	The following tables present the level within the fair value hierarchy at which the Company’s financial assets and financial liabilities are measured on a recurring basis. (at December 31, 2019, in millions) Total Level 1 Level 2 Level 3 Invested assets: Fixed maturities U.S. Treasury securities and obligations of U.S. government and government agencies and authorities $ 2,095 $ 2,095 $ — $ — Obligations of states, municipalities and political subdivisions 29,917 — 29,905 12 Debt securities issued by foreign governments 1,173 — 1,173 — Mortgage-backed securities, collateralized mortgage obligations and pass-through securities 3,280 — 3,280 — All other corporate bonds 31,619 — 31,530 89 Redeemable preferred stock 50 — 50 — Total fixed maturities 68,134 2,095 65,938 101 Equity securities Public common stock 383 383 — — Non-redeemable preferred stock 42 13 29 — Total equity securities 425 396 29 — Other investments 36 16 — 20 Total $ 68,595 $ 2,507 $ 65,967 $ 121 Other liabilities $ 8 $ — $ — $ 8 (at December 31, 2018, in millions) Total Level 1 Level 2 Level 3 Invested assets: Fixed maturities U.S. Treasury securities and obligations of U.S. government and government agencies and authorities $ 2,064 $ 2,064 $ — $ — Obligations of states, municipalities and political subdivisions 28,611 — 28,599 12 Debt securities issued by foreign governments 1,257 — 1,257 — Mortgage-backed securities, collateralized mortgage obligations and pass-through securities 2,573 — 2,554 19 All other corporate bonds 28,880 — 28,725 155 Redeemable preferred stock 79 3 76 — Total fixed maturities 63,464 2,067 61,211 186 Equity securities Public common stock 316 316 — — Non-redeemable preferred stock 52 30 22 — Total equity securities 368 346 22 — Other investments 52 16 — 36 Total $ 63,884 $ 2,429 $ 61,233 $ 222 Other liabilities $ 10 $ — $ — $ 10
Changes in the Level 3 fair value category [Table Text Block]	(in millions) Fixed Maturities Other Investments Total Balance at December 31, 2017 $ 204 $ 38 $ 242 Total realized and unrealized investment gains (losses): Reported in net realized investment gains (1) 2 7 9 Reported in increases in other comprehensive income (loss) (4 ) — (4 ) Purchases, sales and settlements/maturities: Purchases 146 3 149 Sales (11 ) (12 ) (23 ) Settlements/maturities (71 ) — (71 ) Gross transfers into Level 3 11 — 11 Gross transfers out of Level 3 (91 ) — (91 ) Balance at December 31, 2018 $ 186 $ 36 $ 222 Amount of total realized investment gains (losses) for the period included in the consolidated statement of income attributable to changes in the fair value of assets still held at the reporting date $ — $ — $ — ___________________________________________ (1) Includes impairments on investments held at the end of the period as well as amortization on fixed maturities. The following tables present the changes in the Level 3 fair value category for the years ended December 31, 2019 and 2018 . (in millions) Fixed Maturities Other Investments Total Balance at December 31, 2018 $ 186 $ 36 $ 222 Total realized and unrealized investment gains (losses): Reported in net realized investment gains (1) — 3 3 Reported in increases in other comprehensive income (loss) 4 — 4 Purchases, sales and settlements/maturities: Purchases 38 6 44 Sales (1 ) (25 ) (26 ) Settlements/maturities (19 ) — (19 ) Gross transfers into Level 3 — — — Gross transfers out of Level 3 (107 ) — (107 ) Balance at December 31, 2019 $ 101 $ 20 $ 121 Amount of total realized investment gains (losses) for the period included in the consolidated statement of income attributable to changes in the fair value of assets still held at the reporting date $ — $ — $ — ___________________________________________ (1) Includes impairments on investments held at the end of the period as well as amortization on fixed maturities.
Carrying value and fair value of financial instruments disclosed, but not carried, at fair value and the level within the fair value hierarchy at which such financial instruments are categorized [Table Text Block]	The following tables present the carrying value and fair value of the Company’s financial assets and financial liabilities disclosed, but not carried, at fair value, and the level within the fair value hierarchy at which such assets and liabilities are categorized. (at December 31, 2019, in millions) Carrying Value Fair Value Level 1 Level 2 Level 3 Financial assets: Short-term securities $ 4,943 $ 4,943 $ 685 $ 4,204 $ 54 Financial liabilities: Debt $ 6,458 $ 8,049 $ — $ 8,049 $ — Commercial paper 100 100 — 100 — (at December 31, 2018, in millions) Carrying Value Fair Value Level 1 Level 2 Level 3 Financial assets: Short-term securities $ 3,985 $ 3,985 $ 632 $ 3,316 $ 37 Financial liabilities: Debt $ 6,464 $ 7,128 $ — $ 7,128 $ — Commercial paper 100 100 — 100 —

Reinsurance (Tables)

Reinsurance (Tables)	12 Months Ended
Reinsurance (Tables)	Dec. 31, 2019
Reinsurance Disclosures [Abstract]
Summary of reinsurance financial data [Table Text Block]	The following is a summary of reinsurance financial data reflected in the consolidated statement of income: (for the year ended December 31, in millions) 2019 2018 2017 Written premiums Direct $ 30,022 $ 28,210 $ 26,648 Assumed 1,041 1,042 1,000 Ceded (1,912 ) (1,544 ) (1,429 ) Total net written premiums $ 29,151 $ 27,708 $ 26,219 Earned premiums Direct $ 28,994 $ 27,536 $ 26,189 Assumed 1,076 1,024 965 Ceded (1,798 ) (1,501 ) (1,471 ) Total net earned premiums $ 28,272 $ 27,059 $ 25,683 Percentage of assumed earned premiums to net earned premiums 3.8 % 3.8 % 3.8 % Ceded claims and claim adjustment expenses incurred $ 1,089 $ 1,293 $ 1,225
Reinsurance recoverables [Table Text Block]	Reinsurance recoverables include amounts recoverable on both paid and unpaid claims and claim adjustment expenses and were as follows: (at December 31, in millions) 2019 2018 Gross reinsurance recoverables on paid and unpaid claims and claim adjustment expenses $ 3,476 $ 3,485 Allowance for uncollectible reinsurance (92 ) (110 ) Net reinsurance recoverables 3,384 3,375 Mandatory pools and associations 1,886 2,005 Structured settlements 2,965 2,990 Total reinsurance recoverables $ 8,235 $ 8,370

Goodwill and Other Intangible_2

Goodwill and Other Intangible Assets (Tables)	12 Months Ended
Goodwill and Other Intangible Assets (Tables)	Dec. 31, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill by segment [Table Text Block]	The following table presents the carrying amount of the Company’s goodwill by segment. Each reportable segment includes goodwill associated with the Company’s international business which is subject to the impact of changes in foreign currency exchange rates. (at December 31, in millions) 2019 2018 Business Insurance $ 2,601 $ 2,585 Bond & Specialty Insurance 550 550 Personal Insurance 784 776 Other 26 26 Total $ 3,961 $ 3,937
Other intangible assets subject to amortization [Table Text Block]	The following tables present a summary of the Company’s other intangible assets by major asset class: (at December 31, 2019, in millions) Gross Carrying Amount Accumulated Amortization Net Subject to amortization Customer-related $ 99 $ 21 $ 78 Contract-based (1) 205 179 26 Total subject to amortization 304 200 104 Not subject to amortization 226 — 226 Total $ 530 $ 200 $ 330 (at December 31, 2018, in millions) Gross Carrying Amount Accumulated Amortization Net Subject to amortization Customer-related $ 98 $ 12 $ 86 Contract-based (1) 208 175 33 Total subject to amortization 306 187 119 Not subject to amortization 226 — 226 Total $ 532 $ 187 $ 345 ___________________________________________ (1) Contract-based intangible assets subject to amortization are comprised of fair value adjustments on claims and claim adjustment expense reserves, reinsurance recoverables and other contract-related intangible assets. Fair value adjustments recorded in connection with insurance acquisitions were based on management’s estimate of nominal claims and claim adjustment expense reserves and reinsurance recoverables. The method used calculated a risk adjustment to a risk-free discounted reserve that would, if reserves ran off as expected, produce results that yielded the assumed cost-of-capital on the capital supporting the loss reserves. The fair value adjustments are reported as other intangible assets on the consolidated balance sheet, and the amounts measured in accordance with the acquirer’s accounting policies for insurance contracts have been reported as part of the claims and claim adjustment expense reserves and reinsurance recoverables. The intangible assets are being recognized into income over the expected payment pattern. Because the time value of money and the risk adjustment (cost of capital) components of the intangible assets run off at different rates, the amount recognized in income may be a net benefit in some periods and a net expense in other periods.
Other intangible assets not subject to amortization [Table Text Block]	The following tables present a summary of the Company’s other intangible assets by major asset class: (at December 31, 2019, in millions) Gross Carrying Amount Accumulated Amortization Net Subject to amortization Customer-related $ 99 $ 21 $ 78 Contract-based (1) 205 179 26 Total subject to amortization 304 200 104 Not subject to amortization 226 — 226 Total $ 530 $ 200 $ 330 (at December 31, 2018, in millions) Gross Carrying Amount Accumulated Amortization Net Subject to amortization Customer-related $ 98 $ 12 $ 86 Contract-based (1) 208 175 33 Total subject to amortization 306 187 119 Not subject to amortization 226 — 226 Total $ 532 $ 187 $ 345 ___________________________________________ (1) Contract-based intangible assets subject to amortization are comprised of fair value adjustments on claims and claim adjustment expense reserves, reinsurance recoverables and other contract-related intangible assets. Fair value adjustments recorded in connection with insurance acquisitions were based on management’s estimate of nominal claims and claim adjustment expense reserves and reinsurance recoverables. The method used calculated a risk adjustment to a risk-free discounted reserve that would, if reserves ran off as expected, produce results that yielded the assumed cost-of-capital on the capital supporting the loss reserves. The fair value adjustments are reported as other intangible assets on the consolidated balance sheet, and the amounts measured in accordance with the acquirer’s accounting policies for insurance contracts have been reported as part of the claims and claim adjustment expense reserves and reinsurance recoverables. The intangible assets are being recognized into income over the expected payment pattern. Because the time value of money and the risk adjustment (cost of capital) components of the intangible assets run off at different rates, the amount recognized in income may be a net benefit in some periods and a net expense in other periods.

Insurance Claim Reserves (Table

Insurance Claim Reserves (Tables)	12 Months Ended
Insurance Claim Reserves (Tables)	Dec. 31, 2019
Insurance Loss Reserves [Abstract]
Claims and claim adjustment expense reserves [Table Text Block]	Claims and claim adjustment expense reserves were as follows: (at December 31, in millions) 2019 2018 Property-casualty $ 51,836 $ 50,653 Accident and health 13 15 Total $ 51,849 $ 50,668
Reconciliation of beginning and ending property casualty reserve balances for claims and claim adjustment expenses [Table Text Block]	The following table presents a reconciliation of beginning and ending property casualty reserve balances for claims and claim adjustment expenses: (at and for the year ended December 31, in millions) 2019 2018 2017 Claims and claim adjustment expense reserves at beginning of year $ 50,653 $ 49,633 $ 47,929 Less reinsurance recoverables on unpaid losses 8,182 8,123 7,981 Net reserves at beginning of year 42,471 41,510 39,948 Estimated claims and claim adjustment expenses for claims arising in the current year 18,854 18,614 17,846 Estimated increase (decrease) in claims and claim adjustment expenses for claims arising in prior years 164 (406 ) (458 ) Total increases 19,018 18,208 17,388 Claims and claim adjustment expense payments for claims arising in: Current year 7,734 7,697 7,335 Prior years 10,060 9,363 8,708 Total payments 17,794 17,060 16,043 Unrealized foreign exchange loss (gain) 106 (187 ) 217 Net reserves at end of year 43,801 42,471 41,510 Plus reinsurance recoverables on unpaid losses 8,035 8,182 8,123 Claims and claim adjustment expense reserves at end of year $ 51,836 $ 50,653 $ 49,633
Summary of claims and claim adjustment expense reserves, including certain components, for the Company's major product lines by reporting segment [Table Text Block]	The following is a summary of claims and claim adjustment expense reserves, including certain components, for the Company’s major product lines by reporting segment at December 31, 2019 . (at December 31, 2019, in millions) Net Undiscounted Claims and Claim Adjustment Expense Reserves Discount (Net of Reinsurance) Subtotal: Net Claims and Claim Adjustment Expense Reserves Reinsurance Recoverables on Unpaid Losses (4) Claims and Claim Adjustment Expense Reserves Business Insurance General liability $ 7,749 $ (172 ) $ 7,577 $ 842 $ 8,419 Commercial property 887 — 887 389 1,276 Commercial multi-peril 3,784 — 3,784 175 3,959 Commercial automobile 3,237 — 3,237 259 3,496 Workers’ compensation (1) 16,184 (911 ) 15,273 745 16,018 Bond & Specialty Insurance General liability 1,824 — 1,824 108 1,932 Fidelity and surety 399 — 399 4 403 Personal Insurance Automobile 2,862 — 2,862 486 3,348 Homeowners (excluding Other) 1,168 — 1,168 57 1,225 International - Canada 739 — 739 19 758 Subtotal — claims and allocated claim adjustment expenses for the products presented in the development tables below 38,833 (1,083 ) 37,750 3,084 40,834 Other insurance contracts (2) 3,895 (5 ) 3,890 1,968 5,858 Unallocated loss adjustment expense reserves 2,104 — 2,104 39 2,143 Structured settlements (3) — — — 2,965 2,965 Other 57 — 57 (21 ) 36 Total property-casualty 44,889 (1,088 ) 43,801 8,035 51,836 Accident and health — — — 13 13 Total $ 44,889 $ (1,088 ) $ 43,801 $ 8,048 $ 51,849 ___________________________________________ (1) Net discount amount includes discount of $67 million on reinsurance recoverables for long-term disability and annuity claim payments. (2) Primarily includes residual market, international (other than operations in Canada within the Personal Insurance segment) and runoff assumed reinsurance business. (3) Includes structured settlements in cases where the Company did not receive a release from the claimant. (4) Total reinsurance recoverables (on paid and unpaid losses) at December 31, 2019 were $8.24 billion .
Allocated claim adjustment expense, by accident year, on a historical basis for incurred and paid claims on an undiscounted, net of reinsurance basis [Table Text Block]	Business Insurance General Liability ( dollars in millions ) For the Years Ended December 31, 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance Unaudited Accident Year IBNR Reserves Dec 31, 2019 Cumulative Number of Reported Claims 2010 $ 1,028 $ 1,031 $ 1,021 $ 959 $ 927 $ 912 $ 918 $ 908 $ 911 $ 900 $ 62 27,993 2011 1,004 1,074 1,065 998 972 935 913 908 922 69 27,557 2012 989 985 935 913 892 905 917 920 78 24,920 2013 965 975 958 940 927 933 975 104 22,625 2014 976 989 983 948 956 1,013 159 22,319 2015 998 956 923 967 1,057 165 21,360 2016 1,075 1,058 1,087 1,187 359 19,997 2017 1,133 1,143 1,196 530 18,014 2018 1,253 1,312 841 16,694 2019 1,447 1,231 12,167 Total $ 10,929 Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance Accident Year Unaudited 2010 $ 35 $ 139 $ 324 $ 487 $ 629 $ 702 $ 756 $ 781 $ 800 $ 814 2011 47 187 355 539 660 725 762 799 819 2012 32 150 295 489 589 699 754 811 2013 35 175 363 498 639 745 816 Liability for Claims 2014 37 163 321 515 640 750 And Allocated Claim 2015 36 137 336 558 740 Adjustment Expenses, 2016 35 191 421 649 Net of Reinsurance 2017 40 180 378 2018 42 202 2010 - Before 2019 51 2019 2010 Total $ 6,030 $ 4,899 $ 2,850 Total net liability $ 7,749 Average Annual Percentage Payout of Incurred Claims by Age, Net of Reinsurance Unaudited Years 1 2 3 4 5 6 7 8 9 10 3.6 % 12.6 % 18.0 % 18.9 % 14.0 % 9.8 % 5.8 % 4.3 % 2.1 % 1.6 % Commercial Property ( dollars in millions ) For the Years Ended December 31, 2015 2016 2017 2018 2019 Incurred Claims and Allocated Claims Adjustment Expenses, Net of Reinsurance Unaudited Accident Year IBNR Reserves December 31, 2019 Cumulative Number of Reported Claims 2015 $ 786 $ 750 $ 741 $ 731 $ 737 $ 8 20,162 2016 896 863 820 809 11 22,313 2017 1,209 1,177 1,151 11 25,066 2018 1,093 1,079 10 24,785 2019 1,069 84 22,186 Total $ 4,845 Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance Unaudited Liability for Claims Accident Year And Allocated Claim 2015 $ 376 $ 615 $ 681 $ 699 $ 717 Adjustment Expenses, 2016 441 685 745 767 Net of Reinsurance 2017 618 1,003 1,073 2018 561 928 2015 - Before 2019 610 2019 2015 Total $ 4,095 $ 750 $ 137 Total net liability $ 887 Average Annual Percentage Payout of Incurred Claims by Age, Net of Reinsurance Unaudited Years 1 2 3 4 5 53.6 % 32.6 % 7.5 % 2.5 % 2.5 % Commercial Multi-Peril ( dollars in millions ) For the Years Ended December 31, 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance Unaudited Accident Year IBNR Reserves December 31, 2019 Cumulative Number of Reported Claims 2010 $ 1,711 $ 1,826 $ 1,832 $ 1,861 $ 1,895 $ 1,892 $ 1,898 $ 1,885 $ 1,881 $ 1,868 $ 19 112,074 2011 2,235 2,244 2,269 2,286 2,296 2,287 2,283 2,279 2,272 25 125,867 2012 1,885 1,883 1,903 1,888 1,888 1,867 1,859 1,854 34 104,921 2013 1,615 1,623 1,620 1,609 1,591 1,600 1,599 38 83,818 2014 1,663 1,627 1,625 1,617 1,626 1,627 50 78,292 2015 1,568 1,625 1,593 1,597 1,606 92 71,635 2016 1,662 1,623 1,598 1,590 122 68,888 2017 1,872 1,928 1,956 266 71,220 2018 1,976 2,114 416 68,403 2019 2,017 715 70,798 Total $ 18,503 Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance Accident Year Unaudited 2010 $ 709 $ 1,180 $ 1,395 $ 1,579 $ 1,698 $ 1,763 $ 1,798 $ 1,819 $ 1,834 $ 1,840 2011 1,060 1,573 1,803 1,979 2,088 2,156 2,193 2,222 2,234 2012 795 1,246 1,424 1,590 1,699 1,752 1,780 1,804 2013 644 987 1,167 1,304 1,410 1,475 1,516 Liability for Claims 2014 628 956 1,154 1,328 1,448 1,512 And Allocated Claim 2015 595 970 1,144 1,310 1,409 Adjustment Expenses, 2016 585 950 1,133 1,278 Net of Reinsurance 2017 716 1,199 1,388 2018 792 1,302 2010 - Before 2019 707 2019 2010 Total $ 14,990 $ 3,513 $ 271 Total net liability $ 3,784 Average Annual Percentage Payout of Incurred Claims by Age, Net of Reinsurance Unaudited Years 1 2 3 4 5 6 7 8 9 10 38.9 % 23.2 % 10.8 % 9.3 % 6.2 % 3.5 % 1.9 % 1.3 % 0.7 % 0.3 % Commercial Automobile ( dollars in millions ) For the Years Ended December 31, 2015 2016 2017 2018 2019 Incurred Claims and Allocated Claims Adjustment Expenses, Net of Reinsurance Unaudited Accident Year IBNR Reserves December 31, 2019 Cumulative Number of Reported Claims 2015 $ 1,188 $ 1,202 $ 1,234 $ 1,283 $ 1,298 $ 48 173,545 2016 1,278 1,303 1,371 1,409 94 183,114 2017 1,386 1,501 1,524 219 191,166 2018 1,645 1,742 469 201,578 2019 1,835 838 167,863 Total $ 7,808 Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance Unaudited Liability for Claims Accident Year And Allocated Claim 2015 $ 405 $ 650 $ 885 $ 1,058 $ 1,181 Adjustment Expenses, 2016 412 688 931 1,158 Net of Reinsurance 2017 456 746 1,027 2018 515 848 2015 - Before 2019 539 2019 2015 Total $ 4,753 $ 3,055 $ 182 Total net liability $ 3,237 Average Annual Percentage Payout of Incurred Claims by Age, Net of Reinsurance Unaudited Years 1 2 3 4 5 29.8 % 19.2 % 17.9 % 14.7 % 9.5 % Workers’ Compensation ( dollars in millions ) For the Years Ended December 31, 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance Unaudited Accident Year IBNR Reserves December 31, 2019 Cumulative Number of Reported Claims 2010 $ 1,886 $ 2,042 $ 2,035 $ 2,056 $ 2,049 $ 2,052 $ 2,055 $ 2,021 $ 2,003 $ 1,984 $ 248 117,466 2011 2,284 2,303 2,347 2,350 2,379 2,385 2,363 2,348 2,320 319 136,801 2012 2,447 2,456 2,457 2,456 2,445 2,453 2,416 2,387 367 138,034 2013 2,553 2,545 2,540 2,506 2,463 2,423 2,354 408 134,091 2014 2,554 2,553 2,547 2,476 2,430 2,393 486 129,293 2015 2,644 2,585 2,505 2,441 2,372 636 123,163 2016 2,768 2,690 2,569 2,473 702 122,944 2017 2,779 2,681 2,584 918 120,900 2018 2,744 2,687 1,180 121,460 2019 2,680 1,619 107,298 Total $ 24,234 Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance Accident Year Unaudited 2010 $ 341 $ 750 $ 978 $ 1,133 $ 1,246 $ 1,321 $ 1,385 $ 1,430 $ 1,465 $ 1,490 2011 420 911 1,185 1,365 1,487 1,583 1,652 1,696 1,732 2012 443 940 1,217 1,394 1,536 1,629 1,689 1,735 2013 458 954 1,237 1,413 1,525 1,604 1,659 Liability for Claims 2014 455 944 1,224 1,399 1,505 1,581 And Allocated Claim 2015 430 893 1,154 1,310 1,411 Adjustment Expenses, 2016 421 873 1,118 1,272 Net of Reinsurance 2017 433 890 1,154 2018 440 919 2010 - Before 2019 466 2019 2010 Total $ 13,419 $ 10,815 $ 5,369 Total net liability $ 16,184 Average Annual Percentage Payout of Incurred Claims by Age, Net of Reinsurance Unaudited Years 1 2 3 4 5 6 7 8 9 10 17.8 % 19.7 % 11.2 % 7.2 % 5.1 % 3.7 % 2.8 % 2.0 % 1.7 % 1.3 % Bond & Specialty Insurance General Liability ( dollars in millions ) For the Years Ended December 31, 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance Unaudited Accident Year IBNR Reserves December 31, 2019 Cumulative Number of Reported Claims 2010 $ 571 $ 612 $ 679 $ 679 $ 661 $ 668 $ 653 $ 653 $ 657 $ 660 $ 16 5,677 2011 565 596 639 632 601 545 520 508 506 2 5,213 2012 538 591 614 605 601 599 605 593 60 4,865 2013 510 565 606 630 654 607 586 42 4,456 2014 549 571 563 518 473 452 32 4,356 2015 528 524 486 437 395 38 4,195 2016 512 511 504 520 91 4,326 2017 534 517 526 174 4,455 2018 530 548 243 4,393 2019 588 432 3,400 Total $ 5,374 Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance Accident Year Unaudited 2010 $ 33 $ 152 $ 291 $ 396 $ 482 $ 565 $ 597 $ 623 $ 631 $ 635 2011 33 143 249 324 414 447 476 490 496 2012 38 160 255 342 383 419 436 453 2013 34 154 252 352 400 434 451 Liability for Claims 2014 38 150 239 312 367 407 And Allocated Claim 2015 38 141 234 310 338 Adjustment Expenses, 2016 30 141 233 313 Net of Reinsurance 2017 38 155 262 2018 49 182 2010 - Before 2019 51 2019 2010 Total $ 3,588 $ 1,786 $ 38 Total net liability $ 1,824 Average Annual Percentage Payout of Incurred Claims by Age, Net of Reinsurance Unaudited Years 1 2 3 4 5 6 7 8 9 10 7.2 % 22.1 % 19.5 % 16.2 % 10.9 % 7.9 % 4.1 % 3.1 % 1.2 % 0.6 % Fidelity and Surety ( dollars in millions ) For the Years Ended December 31, 2015 2016 2017 2018 2019 IBNR Reserves December 31, 2019 Cumulative Number of Reported Claims Incurred Claims and Allocated Claims Adjustment Expenses, Net of Reinsurance Accident Year Unaudited 2015 $ 217 $ 191 $ 179 $ 145 $ 137 $ 32 834 2016 226 239 205 208 9 886 2017 244 271 240 22 905 2018 220 235 22 849 2019 203 116 592 Total $ 1,023 Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance Accident Year Unaudited Liability for Claims And Allocated Claim 2015 $ 32 $ 75 $ 87 $ 86 $ 88 Adjustment Expenses, 2016 54 121 142 149 Net of Reinsurance 2017 70 166 194 2018 64 171 2015 - Before 2019 49 2019 2015 Total $ 651 $ 372 $ 27 Total net liability $ 399 Average Annual Percentage Payout of Incurred Claims by Age, Net of Reinsurance Unaudited Years 1 2 3 4 5 26.0 % 37.3 % 10.1 % 1.3 % 1.3 % Personal Insurance Automobile ( dollars in millions ) For the Years Ended December 31, 2015 2016 2017 2018 2019 IBNR Reserves December 31, 2019 Cumulative Number of Reported Claims Incurred Claims and Allocated Claims Adjustment Expenses, Net of Reinsurance Accident Year Unaudited 2015 $ 2,186 $ 2,244 $ 2,236 $ 2,222 $ 2,219 $ 11 757,972 2016 2,779 2,791 2,772 2,752 44 922,014 2017 3,323 3,256 3,221 139 1,061,907 2018 3,281 3,269 347 1,048,084 2019 3,362 858 940,933 Total $ 14,823 Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance Accident Year Unaudited Liability for Claims And Allocated Claim 2015 $ 1,319 $ 1,768 $ 1,985 $ 2,109 $ 2,174 Adjustment Expenses, 2016 1,610 2,203 2,466 2,616 Net of Reinsurance 2017 1,912 2,575 2,887 2018 1,889 2,582 2015 - Before 2019 1,933 2019 2015 Total $ 12,192 $ 2,631 $ 231 Total net liability $ 2,862 Average Annual Percentage Payout of Incurred Claims by Age, Net of Reinsurance Unaudited Years 1 2 3 4 5 58.5 % 20.9 % 9.7 % 5.5 % 2.9 % Homeowners (excluding Other) ( dollars in millions ) For the Years Ended December 31, 2015 2016 2017 2018 2019 IBNR Reserves December 31, 2019 Cumulative Number of Reported Claims Incurred Claims and Allocated Claims Adjustment Expenses, Net of Reinsurance Accident Year Unaudited 2015 $ 1,438 $ 1,454 $ 1,461 $ 1,452 $ 1,443 $ 1 145,136 2016 1,556 1,547 1,525 1,511 8 143,949 2017 2,312 2,340 2,343 49 169,085 2018 2,610 2,574 112 185,384 2019 2,297 447 158,328 Total $ 10,168 Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance Accident Year Unaudited Liability for Claims And Allocated Claim 2015 $ 994 $ 1,333 $ 1,395 $ 1,421 $ 1,429 Adjustment Expenses, 2016 1,049 1,392 1,455 1,479 Net of Reinsurance 2017 1,471 2,059 2,197 2018 1,657 2,298 2015 - Before 2019 1,613 2019 2015 Total $ 9,016 $ 1,152 $ 16 Total net liability $ 1,168 Average Annual Percentage Payout of Incurred Claims by Age, Net of Reinsurance Unaudited Years 1 2 3 4 5 67.1 % 24.1 % 4.8 % 1.7 % 0.6 % International - Canada ( dollars in millions ) For the Years Ended December 31, IBNR Reserves December 31, 2019 Cumulative 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 Number of Accident Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance Reported Year Unaudited Claims 2010 $ 487 $ 488 $ 499 $ 514 $ 501 $ 493 $ 489 $ 482 $ 481 $ 477 $ 1 54,938 2011 459 438 446 441 434 427 422 417 408 (5 ) 55,773 2012 435 413 414 398 397 380 374 362 (2 ) 51,208 2013 485 478 469 457 444 443 433 — 54,251 2014 429 444 445 433 426 423 (9 ) 52,268 2015 361 360 360 356 358 10 45,203 2016 361 409 409 419 19 45,759 2017 346 381 403 34 46,769 2018 440 462 64 50,302 2019 445 110 44,796 Total $ 4,190 Accident Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance Year Unaudited 2010 $ 191 $ 292 $ 329 $ 369 $ 400 $ 430 $ 447 $ 459 $ 465 $ 468 2011 176 249 280 314 349 371 389 397 401 2012 165 231 262 288 316 333 342 347 2013 194 272 304 336 369 387 405 Liability for Claims 2014 189 265 302 331 362 384 And Allocated Claim 2015 162 226 253 282 307 Adjustment Expenses, 2016 211 283 310 343 Net of Reinsurance 2017 182 257 296 2018 219 305 2010 - Before 2019 216 2019 2010 Total $ 3,472 $ 718 $ 21 Total net liability $ 739 Average Annual Percentage Payout of Incurred Claims by Age, Net of Reinsurance Unaudited Years 1 2 3 4 5 6 7 8 9 10 45.5 % 18.4 % 8.0 % 7.8 % 7.4 % 5.2 % 3.6 % 1.9 % 1.1 % 0.7 %
Historical average annual percentage payout of incurred claims by age of accident year [Table Text Block]	Business Insurance General Liability ( dollars in millions ) For the Years Ended December 31, 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance Unaudited Accident Year IBNR Reserves Dec 31, 2019 Cumulative Number of Reported Claims 2010 $ 1,028 $ 1,031 $ 1,021 $ 959 $ 927 $ 912 $ 918 $ 908 $ 911 $ 900 $ 62 27,993 2011 1,004 1,074 1,065 998 972 935 913 908 922 69 27,557 2012 989 985 935 913 892 905 917 920 78 24,920 2013 965 975 958 940 927 933 975 104 22,625 2014 976 989 983 948 956 1,013 159 22,319 2015 998 956 923 967 1,057 165 21,360 2016 1,075 1,058 1,087 1,187 359 19,997 2017 1,133 1,143 1,196 530 18,014 2018 1,253 1,312 841 16,694 2019 1,447 1,231 12,167 Total $ 10,929 Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance Accident Year Unaudited 2010 $ 35 $ 139 $ 324 $ 487 $ 629 $ 702 $ 756 $ 781 $ 800 $ 814 2011 47 187 355 539 660 725 762 799 819 2012 32 150 295 489 589 699 754 811 2013 35 175 363 498 639 745 816 Liability for Claims 2014 37 163 321 515 640 750 And Allocated Claim 2015 36 137 336 558 740 Adjustment Expenses, 2016 35 191 421 649 Net of Reinsurance 2017 40 180 378 2018 42 202 2010 - Before 2019 51 2019 2010 Total $ 6,030 $ 4,899 $ 2,850 Total net liability $ 7,749 Average Annual Percentage Payout of Incurred Claims by Age, Net of Reinsurance Unaudited Years 1 2 3 4 5 6 7 8 9 10 3.6 % 12.6 % 18.0 % 18.9 % 14.0 % 9.8 % 5.8 % 4.3 % 2.1 % 1.6 % Commercial Property ( dollars in millions ) For the Years Ended December 31, 2015 2016 2017 2018 2019 Incurred Claims and Allocated Claims Adjustment Expenses, Net of Reinsurance Unaudited Accident Year IBNR Reserves December 31, 2019 Cumulative Number of Reported Claims 2015 $ 786 $ 750 $ 741 $ 731 $ 737 $ 8 20,162 2016 896 863 820 809 11 22,313 2017 1,209 1,177 1,151 11 25,066 2018 1,093 1,079 10 24,785 2019 1,069 84 22,186 Total $ 4,845 Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance Unaudited Liability for Claims Accident Year And Allocated Claim 2015 $ 376 $ 615 $ 681 $ 699 $ 717 Adjustment Expenses, 2016 441 685 745 767 Net of Reinsurance 2017 618 1,003 1,073 2018 561 928 2015 - Before 2019 610 2019 2015 Total $ 4,095 $ 750 $ 137 Total net liability $ 887 Average Annual Percentage Payout of Incurred Claims by Age, Net of Reinsurance Unaudited Years 1 2 3 4 5 53.6 % 32.6 % 7.5 % 2.5 % 2.5 % Commercial Multi-Peril ( dollars in millions ) For the Years Ended December 31, 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance Unaudited Accident Year IBNR Reserves December 31, 2019 Cumulative Number of Reported Claims 2010 $ 1,711 $ 1,826 $ 1,832 $ 1,861 $ 1,895 $ 1,892 $ 1,898 $ 1,885 $ 1,881 $ 1,868 $ 19 112,074 2011 2,235 2,244 2,269 2,286 2,296 2,287 2,283 2,279 2,272 25 125,867 2012 1,885 1,883 1,903 1,888 1,888 1,867 1,859 1,854 34 104,921 2013 1,615 1,623 1,620 1,609 1,591 1,600 1,599 38 83,818 2014 1,663 1,627 1,625 1,617 1,626 1,627 50 78,292 2015 1,568 1,625 1,593 1,597 1,606 92 71,635 2016 1,662 1,623 1,598 1,590 122 68,888 2017 1,872 1,928 1,956 266 71,220 2018 1,976 2,114 416 68,403 2019 2,017 715 70,798 Total $ 18,503 Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance Accident Year Unaudited 2010 $ 709 $ 1,180 $ 1,395 $ 1,579 $ 1,698 $ 1,763 $ 1,798 $ 1,819 $ 1,834 $ 1,840 2011 1,060 1,573 1,803 1,979 2,088 2,156 2,193 2,222 2,234 2012 795 1,246 1,424 1,590 1,699 1,752 1,780 1,804 2013 644 987 1,167 1,304 1,410 1,475 1,516 Liability for Claims 2014 628 956 1,154 1,328 1,448 1,512 And Allocated Claim 2015 595 970 1,144 1,310 1,409 Adjustment Expenses, 2016 585 950 1,133 1,278 Net of Reinsurance 2017 716 1,199 1,388 2018 792 1,302 2010 - Before 2019 707 2019 2010 Total $ 14,990 $ 3,513 $ 271 Total net liability $ 3,784 Average Annual Percentage Payout of Incurred Claims by Age, Net of Reinsurance Unaudited Years 1 2 3 4 5 6 7 8 9 10 38.9 % 23.2 % 10.8 % 9.3 % 6.2 % 3.5 % 1.9 % 1.3 % 0.7 % 0.3 % Commercial Automobile ( dollars in millions ) For the Years Ended December 31, 2015 2016 2017 2018 2019 Incurred Claims and Allocated Claims Adjustment Expenses, Net of Reinsurance Unaudited Accident Year IBNR Reserves December 31, 2019 Cumulative Number of Reported Claims 2015 $ 1,188 $ 1,202 $ 1,234 $ 1,283 $ 1,298 $ 48 173,545 2016 1,278 1,303 1,371 1,409 94 183,114 2017 1,386 1,501 1,524 219 191,166 2018 1,645 1,742 469 201,578 2019 1,835 838 167,863 Total $ 7,808 Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance Unaudited Liability for Claims Accident Year And Allocated Claim 2015 $ 405 $ 650 $ 885 $ 1,058 $ 1,181 Adjustment Expenses, 2016 412 688 931 1,158 Net of Reinsurance 2017 456 746 1,027 2018 515 848 2015 - Before 2019 539 2019 2015 Total $ 4,753 $ 3,055 $ 182 Total net liability $ 3,237 Average Annual Percentage Payout of Incurred Claims by Age, Net of Reinsurance Unaudited Years 1 2 3 4 5 29.8 % 19.2 % 17.9 % 14.7 % 9.5 % Workers’ Compensation ( dollars in millions ) For the Years Ended December 31, 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance Unaudited Accident Year IBNR Reserves December 31, 2019 Cumulative Number of Reported Claims 2010 $ 1,886 $ 2,042 $ 2,035 $ 2,056 $ 2,049 $ 2,052 $ 2,055 $ 2,021 $ 2,003 $ 1,984 $ 248 117,466 2011 2,284 2,303 2,347 2,350 2,379 2,385 2,363 2,348 2,320 319 136,801 2012 2,447 2,456 2,457 2,456 2,445 2,453 2,416 2,387 367 138,034 2013 2,553 2,545 2,540 2,506 2,463 2,423 2,354 408 134,091 2014 2,554 2,553 2,547 2,476 2,430 2,393 486 129,293 2015 2,644 2,585 2,505 2,441 2,372 636 123,163 2016 2,768 2,690 2,569 2,473 702 122,944 2017 2,779 2,681 2,584 918 120,900 2018 2,744 2,687 1,180 121,460 2019 2,680 1,619 107,298 Total $ 24,234 Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance Accident Year Unaudited 2010 $ 341 $ 750 $ 978 $ 1,133 $ 1,246 $ 1,321 $ 1,385 $ 1,430 $ 1,465 $ 1,490 2011 420 911 1,185 1,365 1,487 1,583 1,652 1,696 1,732 2012 443 940 1,217 1,394 1,536 1,629 1,689 1,735 2013 458 954 1,237 1,413 1,525 1,604 1,659 Liability for Claims 2014 455 944 1,224 1,399 1,505 1,581 And Allocated Claim 2015 430 893 1,154 1,310 1,411 Adjustment Expenses, 2016 421 873 1,118 1,272 Net of Reinsurance 2017 433 890 1,154 2018 440 919 2010 - Before 2019 466 2019 2010 Total $ 13,419 $ 10,815 $ 5,369 Total net liability $ 16,184 Average Annual Percentage Payout of Incurred Claims by Age, Net of Reinsurance Unaudited Years 1 2 3 4 5 6 7 8 9 10 17.8 % 19.7 % 11.2 % 7.2 % 5.1 % 3.7 % 2.8 % 2.0 % 1.7 % 1.3 % Bond & Specialty Insurance General Liability ( dollars in millions ) For the Years Ended December 31, 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance Unaudited Accident Year IBNR Reserves December 31, 2019 Cumulative Number of Reported Claims 2010 $ 571 $ 612 $ 679 $ 679 $ 661 $ 668 $ 653 $ 653 $ 657 $ 660 $ 16 5,677 2011 565 596 639 632 601 545 520 508 506 2 5,213 2012 538 591 614 605 601 599 605 593 60 4,865 2013 510 565 606 630 654 607 586 42 4,456 2014 549 571 563 518 473 452 32 4,356 2015 528 524 486 437 395 38 4,195 2016 512 511 504 520 91 4,326 2017 534 517 526 174 4,455 2018 530 548 243 4,393 2019 588 432 3,400 Total $ 5,374 Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance Accident Year Unaudited 2010 $ 33 $ 152 $ 291 $ 396 $ 482 $ 565 $ 597 $ 623 $ 631 $ 635 2011 33 143 249 324 414 447 476 490 496 2012 38 160 255 342 383 419 436 453 2013 34 154 252 352 400 434 451 Liability for Claims 2014 38 150 239 312 367 407 And Allocated Claim 2015 38 141 234 310 338 Adjustment Expenses, 2016 30 141 233 313 Net of Reinsurance 2017 38 155 262 2018 49 182 2010 - Before 2019 51 2019 2010 Total $ 3,588 $ 1,786 $ 38 Total net liability $ 1,824 Average Annual Percentage Payout of Incurred Claims by Age, Net of Reinsurance Unaudited Years 1 2 3 4 5 6 7 8 9 10 7.2 % 22.1 % 19.5 % 16.2 % 10.9 % 7.9 % 4.1 % 3.1 % 1.2 % 0.6 % Fidelity and Surety ( dollars in millions ) For the Years Ended December 31, 2015 2016 2017 2018 2019 IBNR Reserves December 31, 2019 Cumulative Number of Reported Claims Incurred Claims and Allocated Claims Adjustment Expenses, Net of Reinsurance Accident Year Unaudited 2015 $ 217 $ 191 $ 179 $ 145 $ 137 $ 32 834 2016 226 239 205 208 9 886 2017 244 271 240 22 905 2018 220 235 22 849 2019 203 116 592 Total $ 1,023 Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance Accident Year Unaudited Liability for Claims And Allocated Claim 2015 $ 32 $ 75 $ 87 $ 86 $ 88 Adjustment Expenses, 2016 54 121 142 149 Net of Reinsurance 2017 70 166 194 2018 64 171 2015 - Before 2019 49 2019 2015 Total $ 651 $ 372 $ 27 Total net liability $ 399 Average Annual Percentage Payout of Incurred Claims by Age, Net of Reinsurance Unaudited Years 1 2 3 4 5 26.0 % 37.3 % 10.1 % 1.3 % 1.3 % Personal Insurance Automobile ( dollars in millions ) For the Years Ended December 31, 2015 2016 2017 2018 2019 IBNR Reserves December 31, 2019 Cumulative Number of Reported Claims Incurred Claims and Allocated Claims Adjustment Expenses, Net of Reinsurance Accident Year Unaudited 2015 $ 2,186 $ 2,244 $ 2,236 $ 2,222 $ 2,219 $ 11 757,972 2016 2,779 2,791 2,772 2,752 44 922,014 2017 3,323 3,256 3,221 139 1,061,907 2018 3,281 3,269 347 1,048,084 2019 3,362 858 940,933 Total $ 14,823 Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance Accident Year Unaudited Liability for Claims And Allocated Claim 2015 $ 1,319 $ 1,768 $ 1,985 $ 2,109 $ 2,174 Adjustment Expenses, 2016 1,610 2,203 2,466 2,616 Net of Reinsurance 2017 1,912 2,575 2,887 2018 1,889 2,582 2015 - Before 2019 1,933 2019 2015 Total $ 12,192 $ 2,631 $ 231 Total net liability $ 2,862 Average Annual Percentage Payout of Incurred Claims by Age, Net of Reinsurance Unaudited Years 1 2 3 4 5 58.5 % 20.9 % 9.7 % 5.5 % 2.9 % Homeowners (excluding Other) ( dollars in millions ) For the Years Ended December 31, 2015 2016 2017 2018 2019 IBNR Reserves December 31, 2019 Cumulative Number of Reported Claims Incurred Claims and Allocated Claims Adjustment Expenses, Net of Reinsurance Accident Year Unaudited 2015 $ 1,438 $ 1,454 $ 1,461 $ 1,452 $ 1,443 $ 1 145,136 2016 1,556 1,547 1,525 1,511 8 143,949 2017 2,312 2,340 2,343 49 169,085 2018 2,610 2,574 112 185,384 2019 2,297 447 158,328 Total $ 10,168 Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance Accident Year Unaudited Liability for Claims And Allocated Claim 2015 $ 994 $ 1,333 $ 1,395 $ 1,421 $ 1,429 Adjustment Expenses, 2016 1,049 1,392 1,455 1,479 Net of Reinsurance 2017 1,471 2,059 2,197 2018 1,657 2,298 2015 - Before 2019 1,613 2019 2015 Total $ 9,016 $ 1,152 $ 16 Total net liability $ 1,168 Average Annual Percentage Payout of Incurred Claims by Age, Net of Reinsurance Unaudited Years 1 2 3 4 5 67.1 % 24.1 % 4.8 % 1.7 % 0.6 % International - Canada ( dollars in millions ) For the Years Ended December 31, IBNR Reserves December 31, 2019 Cumulative 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 Number of Accident Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance Reported Year Unaudited Claims 2010 $ 487 $ 488 $ 499 $ 514 $ 501 $ 493 $ 489 $ 482 $ 481 $ 477 $ 1 54,938 2011 459 438 446 441 434 427 422 417 408 (5 ) 55,773 2012 435 413 414 398 397 380 374 362 (2 ) 51,208 2013 485 478 469 457 444 443 433 — 54,251 2014 429 444 445 433 426 423 (9 ) 52,268 2015 361 360 360 356 358 10 45,203 2016 361 409 409 419 19 45,759 2017 346 381 403 34 46,769 2018 440 462 64 50,302 2019 445 110 44,796 Total $ 4,190 Accident Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance Year Unaudited 2010 $ 191 $ 292 $ 329 $ 369 $ 400 $ 430 $ 447 $ 459 $ 465 $ 468 2011 176 249 280 314 349 371 389 397 401 2012 165 231 262 288 316 333 342 347 2013 194 272 304 336 369 387 405 Liability for Claims 2014 189 265 302 331 362 384 And Allocated Claim 2015 162 226 253 282 307 Adjustment Expenses, 2016 211 283 310 343 Net of Reinsurance 2017 182 257 296 2018 219 305 2010 - Before 2019 216 2019 2010 Total $ 3,472 $ 718 $ 21 Total net liability $ 739 Average Annual Percentage Payout of Incurred Claims by Age, Net of Reinsurance Unaudited Years 1 2 3 4 5 6 7 8 9 10 45.5 % 18.4 % 8.0 % 7.8 % 7.4 % 5.2 % 3.6 % 1.9 % 1.1 % 0.7 %

Debt (Tables)

Debt (Tables)	12 Months Ended
Debt (Tables)	Dec. 31, 2019
Debt Disclosure [Abstract]
Debt outstanding [Table Text Block]	Debt outstanding was as follows: (at December 31, in millions) 2019 2018 Short-term: Commercial paper $ 100 $ 100 3.90% Senior notes due November 1, 2020 500 — 5.90% Senior notes due June 2, 2019 — 500 Total short-term debt 600 600 Long-term: 3.90% Senior notes due November 1, 2020 — 500 7.75% Senior notes due April 15, 2026 200 200 7.625% Junior subordinated debentures due December 15, 2027 125 125 6.375% Senior notes due March 15, 2033 500 500 6.75% Senior notes due June 20, 2036 400 400 6.25% Senior notes due June 15, 2037 800 800 5.35% Senior notes due November 1, 2040 750 750 4.60% Senior notes due August 1, 2043 500 500 4.30% Senior notes due August 25, 2045 400 400 8.50% Junior subordinated debentures due December 15, 2045 56 56 3.75% Senior notes due May 15, 2046 500 500 8.312% Junior subordinated debentures due July 1, 2046 73 73 4.00% Senior notes due May 30, 2047 700 700 4.05% Senior notes due March 7, 2048 500 500 4.10% Senior notes due March 4, 2049 500 — Total long-term debt 6,004 6,004 Total debt principal 6,604 6,604 Unamortized fair value adjustment 43 44 Unamortized debt issuance costs (89 ) (84 ) Total debt $ 6,558 $ 6,564
Merger-related unamortized fair value adjustments and the related effective interest rate [Table Text Block]	The following table presents merger-related unamortized fair value adjustments and the related effective interest rate: Unamortized Fair Value Purchase Adjustment at December 31, Effective Interest Rate to Maturity (in millions) Issue Rate Maturity Date 2019 2018 Junior subordinated debentures 7.625 % Dec. 2027 $ 11 $ 12 6.147 % 8.500 % Dec. 2045 14 14 6.362 % 8.312 % Jul. 2046 18 18 6.362 % Total $ 43 $ 44

Shareholders' Equity and Divi_2

Shareholders' Equity and Dividend Availability (Table)	12 Months Ended
Shareholders' Equity and Dividend Availability (Table)	Dec. 31, 2019
Stockholders' Equity Note [Abstract]
Share repurchase activity and remaining repurchase capacity under the share repurchase authorization [Table Text Block]	The following table summarizes repurchase activity in 2019 and remaining repurchase capacity at December 31, 2019 . (in millions, except per share amounts) Quarterly Period Ending Number of shares repurchased Cost of shares repurchased Average price paid per share Remaining capacity under share repurchase authorization March 31, 2019 2.9 $ 375 $ 129.42 $ 2,911 June 30, 2019 2.6 375 145.87 2,536 September 30, 2019 2.5 375 147.23 2,161 December 31, 2019 2.8 375 134.33 1,786 Total 10.8 $ 1,500 138.80 1,786

Other Comprehensive Income an_2

Other Comprehensive Income and Accumulated Other Comprehensive Income (Tables)	12 Months Ended
	Dec. 31, 2019
Other Comprehensive Income And Accumulated Other Comprehensive Income Disclosure [Abstract]
Changes in accumulated other comprehensive income (loss) (AOCI) [Table Text Block]	The following table presents the changes in the Company’s accumulated other comprehensive income (AOCI) for the years ended December 31, 2019 , 2018 and 2017 . Changes in Net Unrealized Gains (Losses) on Investment Securities (in millions) Having No Credit Losses Recognized in the Consolidated Statement of Income Having Credit Losses Recognized in the Consolidated Statement of Income Net Benefit Plan Assets and Obligations Recognized in Shareholders’ Equity Net Unrealized Foreign Currency Translation Total Accumulated Other Comprehensive Income (Loss) Balance, December 31, 2016 $ 528 $ 202 $ (703 ) $ (782 ) $ (755 ) Other comprehensive income (loss) (OCI) before reclassifications, net of tax 367 4 (24 ) 171 518 Amounts reclassified from AOCI, net of tax (148 ) 1 41 — (106 ) Net OCI, current period 219 5 17 171 412 Balance, December 31, 2017 747 207 (686 ) (611 ) (343 ) Cumulative effect of adoption of updated accounting guidance for equity financial instruments at January 1, 2018 (34 ) — — — (34 ) Income tax benefit (12 ) — — — (12 ) Net of taxes (22 ) — — — (22 ) Reclassification of certain tax effects from accumulated other comprehensive income at January 1, 2018 145 7 (141 ) (35 ) (24 ) Total effect of adoption of new guidance at January 1, 2018, net of tax 123 7 (141 ) (35 ) (46 ) OCI before reclassifications, net of tax (1,151 ) (21 ) (114 ) (227 ) (1,513 ) Amounts reclassified from AOCI, net of tax (25 ) — 68 — 43 Net OCI, current period (1,176 ) (21 ) (46 ) (227 ) (1,470 ) Balance, December 31, 2018 (306 ) 193 (873 ) (873 ) (1,859 ) OCI before reclassifications, net of tax 2,406 (4 ) (14 ) 106 2,494 Amounts reclassified from AOCI, net of tax (43 ) — 41 7 5 Net OCI, current period 2,363 (4 ) 27 113 2,499 Balance, December 31, 2019 $ 2,057 $ 189 $ (846 ) $ (760 ) $ 640
Pre-tax components of other comprehensive income (loss) and the related income tax expense (benefit) for each component [Table Text Block]	The following table presents the pre-tax components of the Company’s other comprehensive income (loss) and the related income tax expense (benefit). (for the year ended December 31, in millions) 2019 2018 2017 Changes in net unrealized gains (losses) on investment securities: Having no credit losses recognized in the consolidated statement of income $ 2,994 $ (1,489 ) $ 294 Income tax expense (benefit) 631 (313 ) 75 Net of taxes 2,363 (1,176 ) 219 Having credit losses recognized in the consolidated statement of income (4 ) (27 ) 8 Income tax expense (benefit) — (6 ) 3 Net of taxes (4 ) (21 ) 5 Net changes in benefit plan assets and obligations 33 (56 ) 29 Income tax expense (benefit) 6 (10 ) 12 Net of taxes 27 (46 ) 17 Net changes in unrealized foreign currency translation 117 (247 ) 191 Income tax expense (benefit) 4 (20 ) 20 Net of taxes 113 (227 ) 171 Total other comprehensive income (loss) 3,140 (1,819 ) 522 Total income tax expense (benefit) 641 (349 ) 110 Total other comprehensive income (loss), net of taxes $ 2,499 $ (1,470 ) $ 412
Pre-tax and related income tax (expense) benefit components of the amounts reclassified from accumulated other comprehensive income to the consolidated statement of income [Table Text Block]	The following table presents the pre-tax and related income tax (expense) benefit components of the amounts reclassified from the Company’s AOCI to the Company’s consolidated statement of income. (for the year ended December 31, in millions) 2019 2018 2017 Reclassification adjustments related to unrealized gains (losses) on investment securities: Having no credit losses recognized in the consolidated statement of income (1) $ (55 ) $ (32 ) $ (228 ) Income tax expense (2) (12 ) (7 ) (80 ) Net of taxes (43 ) (25 ) (148 ) Having credit losses recognized in the consolidated statement of income (1) — — 1 Income tax benefit (2) — — — Net of taxes — — 1 Reclassification adjustment related to benefit plan assets and obligations: Claims and claim adjustment expenses (3) 21 35 32 General and administrative expenses (3) 31 51 48 Total 52 86 80 Income tax benefit (2) 11 18 39 Net of taxes 41 68 41 Reclassification adjustment related to foreign currency translation (1) 7 — — Income tax benefit (2) — — — Net of taxes 7 — — Total reclassifications 4 54 (147 ) Total income tax (expense) benefit (1 ) 11 (41 ) Total reclassifications, net of taxes $ 5 $ 43 $ (106 ) ___________________________________________ (1) (Increases) decreases net realized investment gains on the consolidated statement of income. (2) (Increases) decreases income tax expense on the consolidated statement of income. (3) Increases (decreases) expenses on the consolidated statement of income.

Earnings per Share (Table)

Earnings per Share (Table)	12 Months Ended
Earnings per Share (Table)	Dec. 31, 2019
Earnings Per Share Reconciliation [Abstract]
Earnings per share reconciliation [Table Text Block]	The following is a reconciliation of the income and share data used in the basic and diluted earnings per share computations: (for the year ended December 31, in millions, except per share amounts) 2019 2018 2017 Basic and Diluted Net income, as reported $ 2,622 $ 2,523 $ 2,056 Participating securities — allocated income (19 ) (19 ) (15 ) Net income available to common shareholders — basic and diluted $ 2,603 $ 2,504 $ 2,041 Common Shares Basic Weighted average shares outstanding 260.0 267.4 276.0 Diluted Weighted average shares outstanding 260.0 267.4 276.0 Weighted average effects of dilutive securities: Stock options and performance shares 2.3 2.4 2.6 Total 262.3 269.8 278.6 Net income Per Common Share 0 Basic $ 10.01 $ 9.37 $ 7.39 Diluted $ 9.92 $ 9.28 $ 7.33

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
Income Taxes (Tables)	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Composition of income tax expense included in consolidated statement of income and shareholders' equity [Table Text Block]	The following table presents the components of income tax expense included in the amounts reported in the Company’s consolidated financial statements: (for the year ended December 31, in millions) 2019 2018 2017 Composition of income tax expense included in the consolidated statement of income Current expense: Federal $ 546 $ 424 $ 314 Impact of TCJA at enactment — — 21 Foreign 7 41 56 State 6 8 4 Total current tax expense 559 473 395 Deferred expense (benefit): Federal (33 ) (13 ) 229 Impact of TCJA at enactment — — 108 Foreign (10 ) (22 ) (58 ) Total deferred tax expense (benefit) (43 ) (35 ) 279 Total income tax expense included in the consolidated statement of income 516 438 674 Composition of income tax expense (benefit) included in shareholders’ equity Expense (benefit) relating to changes in the unrealized gain (loss) on investments, unrealized loss on foreign exchange and other items in other comprehensive income (loss) 641 (349 ) 110 Total income tax expense included in the consolidated financial statements $ 1,157 $ 89 $ 784
Effective tax rate [Table Text Block]	The following is a reconciliation of income tax expense at the U.S. federal statutory income tax rate to the income tax expense reported in the Company’s consolidated statement of income: (for the year ended December 31, in millions) 2019 2018 2017 Income (loss) before income taxes U.S. $ 3,211 $ 3,039 $ 2,798 Foreign (73 ) (78 ) (68 ) Total income before income taxes 3,138 2,961 2,730 Effective tax rate Statutory tax rate 21 % 21 % 35 % Expected federal income tax expense 659 622 956 Tax effect of: Nontaxable investment income (149 ) (150 ) (297 ) TCJA at enactment — — 129 Other, net 6 (34 ) (114 ) Total income tax expense $ 516 $ 438 $ 674 Effective tax rate 16 % 15 % 25 %
Deferred tax assets and liabilities [Table Text Block]	The net deferred tax asset (liability) comprises the tax effects of temporary differences related to the following assets and liabilities: (at December 31, in millions) 2019 2018 Deferred tax assets Claims and claim adjustment expense reserves $ 551 $ 571 Unearned premium reserves 539 503 Compensation-related liabilities 97 92 Other 243 200 Total gross deferred tax assets 1,430 1,366 Less: valuation allowance 27 8 Adjusted gross deferred tax assets 1,403 1,358 Deferred tax liabilities Claims and claim adjustment expense reserve discounting (transition rule) 115 159 Deferred acquisition costs 427 397 Investments 781 152 Internally developed software 94 92 Depreciation 70 67 Other 53 46 Total gross deferred tax liabilities 1,540 913 Net deferred tax asset (liability) $ (137 ) $ 445
Net operating loss amounts by jurisdiction and year of expiration [Table Text Block]	The NOL amounts by jurisdiction and year of expiration are as follows: (in millions) Amount Year of expiration United States $ 2 2035 - 2036 Brazil $ 25 None Canada $ 5 2035 - 2039 Republic of Ireland $ 124 None United Kingdom $ 202 None
Reconciliation of unrecognized tax benefits [Table Text Block]	The following is a reconciliation of the beginning and ending amount of unrecognized tax benefits for the years ended December 31, 2019 and 2018 : (in millions) 2019 2018 Balance at January 1 $ 31 $ 6 Additions for tax positions of prior years 8 25 Reductions for tax positions of prior years — — Reductions based on tax positions related to current year — — Expiration of statute of limitations $ (2 ) — Balance at December 31 $ 37 $ 31

Share-Based Incentive Compens_2

Share-Based Incentive Compensation (Tables)	12 Months Ended
Share-Based Incentive Compensation (Tables)	Dec. 31, 2019
Share-based Payment Arrangement [Abstract]
Assumptions used in estimating fair value of options on grant date [Table Text Block]	The following table provides information about options granted: (for the year ended December 31,) 2019 2018 2017 Assumptions used in estimating fair value of options on grant date Expected term of stock options 6 years 6 years 6 years Expected volatility of Company’s stock 15.47% - 15.91% 14.94 % 16.50 % Weighted average volatility 15.48 % 14.94 % 16.50 % Expected annual dividend per share $3.08 - $3.28 $2.88 $2.68 Risk-free rate 1.70% - 2.54% 2.68 % 2.08 % Additional information Weighted average grant-date fair value of options granted (per share) $ 16.64 $ 20.13 $ 16.15 Total intrinsic value of options exercised during the year (in millions) $ 88 $ 67 $ 90
Additional information regarding option grants [Table Text Block]	The following table provides information about options granted: (for the year ended December 31,) 2019 2018 2017 Assumptions used in estimating fair value of options on grant date Expected term of stock options 6 years 6 years 6 years Expected volatility of Company’s stock 15.47% - 15.91% 14.94 % 16.50 % Weighted average volatility 15.48 % 14.94 % 16.50 % Expected annual dividend per share $3.08 - $3.28 $2.88 $2.68 Risk-free rate 1.70% - 2.54% 2.68 % 2.08 % Additional information Weighted average grant-date fair value of options granted (per share) $ 16.64 $ 20.13 $ 16.15 Total intrinsic value of options exercised during the year (in millions) $ 88 $ 67 $ 90
Summary of stock option activity under the Company's 2014 Incentive Plan and legacy share-based incentive compensation plans [Table Text Block]	A summary of stock option activity under the 2014 Incentive Plan and the legacy plans as of and for the year ended December 31, 2019 is as follows: Stock Options Number Weighted Average Exercise Price Weighted Average Contractual Life Remaining Aggregate Intrinsic Value ($ in millions) Outstanding, beginning of year 8,994,356 $ 106.93 Original grants 2,057,494 126.19 Exercised (1,874,412 ) 92.98 Forfeited or expired (114,164 ) 127.55 Outstanding, end of year 9,063,274 $ 113.93 6.3 years $ 215 Vested at end of year (1) 6,025,208 $ 106.91 5.3 years $ 184 Exercisable at end of year 4,001,010 $ 96.37 3.9 years $ 163 ___________________________________________ (1) Represents awards for which the requisite service has been rendered, including those that are retirement eligible.
Summary of restricted stock units, deferred stock units and performance share activity [Table Text Block]	A summary of restricted stock units, deferred stock units and performance share activity under the 2014 Incentive Plan and the legacy plans as of and for the year ended December 31, 2019 is as follows: Restricted and Deferred Stock Units Performance Shares Other Equity Instruments Number Weighted Average Grant-Date Fair Value Number Weighted Average Grant-Date Fair Value Nonvested, beginning of year 1,216,676 $ 122.34 684,889 $ 128.83 Granted 591,365 126.88 371,754 126.18 Vested (592,754 ) (1) 114.17 (365,743 ) (2) 118.78 Forfeited (77,626 ) 127.75 (27,625 ) 129.78 Performance-based adjustment — — 5,472 (3) 123.17 Nonvested, end of year 1,137,661 (4) $ 128.59 668,747 $ 132.76 ___________________________________________ (1) Represents awards for which the requisite service has been rendered. (2) Reflects the number of performance shares attributable to the performance goals attained over the completed performance period ( three years ) and for which service conditions have been met. (3) Represents the current year change in estimated performance shares to reflect the attainment of performance goals for the awards that were granted in each of the years 2017 through 2019 . (4) 95,953 shares of restricted common stock were also issued outside of the 2014 Incentive Plan in 2017 in connection with the acquisition of Simply Business, of which 41,997

Pension Plans, Retirement Ben_2

Pension Plans, Retirement Benefits and Savings Plans (Tables)	12 Months Ended
	Dec. 31, 2019
Retirement Benefits [Abstract]
Summary of the funded status, obligations and amounts recognized in the consolidated balance sheet for the Company's benefit plans [Table Text Block]	The following tables summarize the funded status, obligations and amounts recognized in the consolidated balance sheet for the Company’s benefit plans. The Company uses a December 31 measurement date for its pension and postretirement benefit plans. (at and for the year ended December 31, in millions) Qualified Domestic Pension Plan Nonqualified and Foreign Pension Plans Total 2019 2018 2019 2018 2019 2018 Change in projected benefit obligation: Benefit obligation at beginning of year $ 3,444 $ 3,679 $ 215 $ 230 $ 3,659 $ 3,909 Benefits earned 112 126 6 7 118 133 Interest cost on benefit obligation 134 119 7 7 141 126 Actuarial (gain) loss 451 (273 ) 19 (11 ) 470 (284 ) Benefits paid (187 ) (207 ) (11 ) (12 ) (198 ) (219 ) Foreign currency exchange rate change — — 5 (6 ) 5 (6 ) Benefit obligation at end of year $ 3,954 $ 3,444 $ 241 $ 215 $ 4,195 $ 3,659 Change in plan assets: Fair value of plan assets at beginning of year $ 3,771 $ 3,957 $ 103 $ 113 $ 3,874 $ 4,070 Actual return on plan assets 686 (179 ) 10 (1 ) 696 (180 ) Company contributions — 200 8 10 8 210 Benefits paid (187 ) (207 ) (11 ) (12 ) (198 ) (219 ) Foreign currency exchange rate change — — 5 (7 ) 5 (7 ) Fair value of plan assets at end of year 4,270 3,771 115 103 4,385 3,874 Funded status of plan at end of year $ 316 $ 327 $ (126 ) $ (112 ) $ 190 $ 215 Amounts recognized in the consolidated balance sheet consist of: Accrued over-funded benefit plan assets $ 316 $ 327 $ 1 $ 4 $ 317 $ 331 Accrued under-funded benefit plan liabilities — — (127 ) (116 ) (127 ) (116 ) Total $ 316 $ 327 $ (126 ) $ (112 ) $ 190 $ 215 Amounts recognized in accumulated other comprehensive income consist of: Net actuarial loss $ 1,094 $ 1,113 $ 49 $ 36 $ 1,143 $ 1,149 Prior service cost (benefit) (3 ) (5 ) — 1 (3 ) (4 ) Total $ 1,091 $ 1,108 $ 49 $ 37 $ 1,140 $ 1,145 Postretirement Benefit Plans (at and for the year ended December 31, in millions) 2019 2018 Change in projected benefit obligation: Benefit obligation at beginning of year $ 203 $ 225 Benefits earned — — Interest cost on benefit obligation 7 7 Actuarial gain (31 ) (18 ) Benefits paid (9 ) (10 ) Foreign currency exchange rate change 1 (1 ) Benefit obligation at end of year $ 171 $ 203 Change in plan assets: Fair value of plan assets at beginning of year $ 12 $ 13 Actual return on plan assets 1 — Company contributions 8 9 Benefits paid (9 ) (10 ) Fair value of plan assets at end of year 12 12 Funded status of plan at end of year $ (159 ) $ (191 ) Amounts recognized in the consolidated balance sheet consist of: Accrued under-funded benefit plan liability $ (159 ) $ (191 ) Amounts recognized in accumulated other comprehensive income consist of: Net actuarial gain $ (49 ) $ (17 ) Prior service benefit (21 ) (25 ) Total $ (70 ) $ (42 )
Summary of the components of net periodic benefit cost and other amounts recognized in other comprehensive income related to the benefit plans [Table Text Block]	The following table summarizes the components of net periodic benefit cost and other amounts recognized in other comprehensive income related to the benefit plans. Pension Plans Postretirement Benefit Plans (for the year ended December 31, in millions) 2019 2018 2017 2019 2018 2017 Net Periodic Benefit Cost: Service cost $ 118 $ 133 $ 119 $ — $ — $ — Non-service cost: Interest cost on benefit obligation 141 126 127 7 7 7 Expected return on plan assets (275 ) (264 ) (240 ) (1 ) — — Settlement — — 3 — — — Amortization of unrecognized: Prior service benefit (1 ) (1 ) (1 ) (3 ) (4 ) (4 ) Net actuarial loss 56 91 85 — — — Total non-service cost (benefit) (79 ) (48 ) (26 ) 3 3 3 Net periodic benefit cost 39 85 93 3 3 3 Other Changes in Benefit Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income: Prior service benefit — — — — — — Net actuarial loss (gain) 49 160 40 (31 ) (18 ) 13 Foreign currency exchange rate change 1 (1 ) 2 — — (1 ) Settlement — — (2 ) — — — Amortization of prior service benefit 1 1 1 3 4 4 Amortization of net actuarial loss (56 ) (91 ) (85 ) — — — Total other changes recognized in other comprehensive income (5 ) 69 (44 ) (28 ) (14 ) 16 Total other changes recognized in net periodic benefit cost and other comprehensive income $ 34 $ 154 $ 49 $ (25 ) $ (11 ) $ 19
Consolidated statement of income line items impacted by service costs and non-service benefit costs [Table Text Block]	The following table indicates the line items in which the respective service costs and non-service cost (benefit) are presented in the consolidated statement of income for the years ended December 31, 2019 , 2018 and 2017 . Pension Plans Postretirement Benefit Plans (for the year ended December 31, in millions) 2019 2018 2017 2019 2018 2017 Service Cost: Net investment income $ 1 $ 1 $ — $ — $ — $ — Claims and claim adjustment expenses 48 54 48 — — — General and administrative expenses 69 78 71 — — — Total service cost 118 133 119 — — — Non-Service Cost (Benefit): Claims and claim adjustment expenses (33 ) (19 ) (11 ) 1 1 1 General and administrative expenses (46 ) (29 ) (15 ) 2 2 2 Total non-service cost (benefit) (79 ) (48 ) (26 ) 3 3 3 Net periodic benefit cost $ 39 $ 85 $ 93 $ 3 $ 3 $ 3
Benefit obligations assumptions, net periodic benefit cost assumptions and health care cost trend rates [Table Text Block]	The following table summarizes assumptions used with regard to the Company’s qualified and nonqualified domestic pension plans and the domestic postretirement benefit plans. (at and for the year ended December 31,) 2019 2018 Assumptions used to determine benefit obligations Discount rate: Qualified domestic pension plan 3.28 % 4.39 % Nonqualified domestic pension plan 3.17 % 4.33 % Domestic postretirement benefit plan 3.09 % 4.26 % Cash balance interest crediting rate 4.01 % 4.01 % Future compensation increase rate 4.00 % 4.00 % Assumptions used to determine net periodic benefit cost Discount rate: Qualified domestic pension plan: Service cost 4.57 % 3.87 % Interest cost 4.02 % 3.34 % Nonqualified domestic pension plan: Service cost 4.40 % 3.73 % Interest cost 3.95 % 3.26 % Domestic postretirement benefit plan: Interest cost 3.90 % 3.21 % Expected long-term rate of return on assets: Pension plan 7.00 % 7.00 % Postretirement benefit plan 4.00 % 4.00 % Assumed health care cost trend rates Following year: Medical (before age 65) 7.00 % 7.50 % Medical (age 65 and older) 8.25 % 8.75 % Rate to which the cost trend rate is assumed to decline (ultimate trend rate) 4.50 % 4.50 % Year that the rate reaches the ultimate trend rate: Medical (before age 65) 2026 2026 Medical (age 65 and older) 2026 2026
Level within the fair value hierarchy at which the financial assets of the Company's pension plans are measured [Table Text Block]	The following tables present the level within the fair value hierarchy at which the financial assets of the Company’s pension plans are measured on a recurring basis. (at December 31, 2019, in millions) Total Level 1 Level 2 Level 3 Invested assets: Fixed maturities Obligations of states, municipalities and political subdivisions $ 3 $ — $ 3 $ — Debt securities issued by foreign governments 30 — 30 — Mortgage-backed securities, collateralized mortgage obligations and pass-through securities 30 — 30 — All other corporate bonds 715 — 715 — Total fixed maturities 778 — 778 — Mutual funds Equity mutual funds 1,585 1,578 7 — Bond mutual funds 869 866 3 — Total mutual funds 2,454 2,444 10 — Equity securities 1,018 1,017 1 — Other investments 2 — — 2 Cash and short-term securities U.S. Treasury securities 20 20 — — Money market mutual funds 27 27 — — Other 86 17 69 — Total cash and short-term securities 133 64 69 — Total $ 4,385 $ 3,525 $ 858 $ 2 (at December 31, 2018, in millions) Total Level 1 Level 2 Level 3 Invested assets: Fixed maturities Obligations of states, municipalities and political subdivisions $ 3 $ — $ 3 $ — Debt securities issued by foreign governments 27 — 27 — Mortgage-backed securities, collateralized mortgage obligations and pass-through securities 30 — 30 — All other corporate bonds 712 — 712 — Total fixed maturities 772 — 772 — Mutual funds Equity mutual funds 1,288 1,282 6 — Bond mutual funds 760 757 3 — Total mutual funds 2,048 2,039 9 — Equity securities 783 783 — — Other investments 1 — — 1 Cash and short-term securities U.S. Treasury securities 30 30 — — Money market mutual funds — — — — Other 240 19 221 — Total cash and short-term securities 270 49 221 — Total $ 3,874 $ 2,871 $ 1,002 $ 1
Estimated future benefit payments [Table Text Block]	The following table presents the estimated benefits expected to be paid by the Company’s pension and postretirement benefit plans for the next ten years (reflecting estimated future employee service). Benefits Expected to be Paid (in millions) Pension Plans Postretirement Benefit Plans 2020 $ 250 $ 12 2021 261 12 2022 265 12 2023 273 12 2024 276 12 2025 through 2029 1,400 55

Leases (Tables)

Leases (Tables)	12 Months Ended
Leases (Tables)	Dec. 31, 2019
Leases [Abstract]
Additional information regarding real estate operating leases	Lease expense is included in general and administrative expenses in the consolidated statement of income. Additional information regarding the Company’s real estate operating leases is as follows: (for the year ended December 31, in millions) 2019 Lease cost Operating leases $ 92 Short-term leases (1) 10 Lease expense 102 Less: sublease income (2) — Net lease cost $ 102 Other information on operating leases Cash payments to settle a lease liability reported in cash flows $ 104 Right-of-use assets obtained in exchange for new lease liabilities $ 60 Weighted average discount rate 3.02 % Weighted average remaining lease term in years 5.1 years _________________________________________________________ (1) Leases with an initial term of twelve months or less are not recorded on the balance sheet. (2) Sublease income consists of rent from third parties of office space and is recognized as part of other revenues in the consolidated statement of income.
Contractual maturities of lease liabilities	The following table presents the contractual maturities of the Company's lease liabilities: (in millions) Real Estate Lease Liability 2020 $ 108 2021 93 2022 71 2023 51 2024 35 Thereafter 54 Total undiscounted lease payments 412 Less: present value adjustment 32 Operating lease liability $ 380

Consolidating Financial State_2

Consolidating Financial Statements (Tables)	12 Months Ended
Consolidating Financial Statements (Tables)	Dec. 31, 2019
Consolidating Financial Statements of The Travelers Companies, Inc. and Subsidiaries (Unaudited) disclosure
Consolidating Statement of Income (Unaudited) [Table Text Block]	CONSOLIDATING STATEMENT OF INCOME (Unaudited) For the year ended December 31, 2019 (in millions) TPC Other Subsidiaries TRV Eliminations Consolidated Revenues Premiums $ 19,362 $ 8,910 $ — $ — $ 28,272 Net investment income 1,730 697 41 — 2,468 Fee income 458 1 — — 459 Net realized investment gains (1) 44 36 33 — 113 Other revenues 142 127 — — 269 Total revenues 21,736 9,771 74 — 31,581 Claims and expenses Claims and claim adjustment expenses 12,926 6,207 — — 19,133 Amortization of deferred acquisition costs 3,095 1,506 — — 4,601 General and administrative expenses 2,973 1,371 21 — 4,365 Interest expense 47 — 297 — 344 Total claims and expenses 19,041 9,084 318 — 28,443 Income (loss) before income taxes 2,695 687 (244 ) — 3,138 Income tax expense (benefit) 483 110 (77 ) — 516 Net income of subsidiaries — — 2,789 (2,789 ) — Net income $ 2,212 $ 577 $ 2,622 $ (2,789 ) $ 2,622 ___________________________________________ (1) Total other-than-temporary impairments (OTTI) for the year ended December 31, 2019 , and the amounts comprising total OTTI that were recognized in net realized investment gains and in other comprehensive income (OCI), were as follows: (in millions) TPC Other Subsidiaries TRV Eliminations Consolidated Total OTTI losses $ (2 ) $ (1 ) $ — $ — $ (3 ) OTTI losses recognized in net realized investment gains $ (2 ) $ (2 ) $ — $ — $ (4 ) OTTI gains recognized in OCI $ — $ 1 $ — $ — $ 1 CONSOLIDATING STATEMENT OF INCOME (Unaudited) For the year ended December 31, 2018 (in millions) TPC Other Subsidiaries TRV Eliminations Consolidated Revenues Premiums $ 18,508 $ 8,551 $ — $ — $ 27,059 Net investment income 1,704 738 32 — 2,474 Fee income 432 — — — 432 Net realized investment gains (losses) (1) 118 9 (13 ) — 114 Other revenues 96 112 — (5 ) 203 Total revenues 20,858 9,410 19 (5 ) 30,282 Claims and expenses Claims and claim adjustment expenses 12,344 5,947 — — 18,291 Amortization of deferred acquisition costs 2,972 1,409 — — 4,381 General and administrative expenses 2,947 1,335 20 (5 ) 4,297 Interest expense 48 — 304 — 352 Total claims and expenses 18,311 8,691 324 (5 ) 27,321 Income (loss) before income taxes 2,547 719 (305 ) — 2,961 Income tax expense (benefit) 437 115 (114 ) — 438 Net income of subsidiaries — — 2,714 (2,714 ) — Net income $ 2,110 $ 604 $ 2,523 $ (2,714 ) $ 2,523 ___________________________________________ (1) Total other-than-temporary impairments (OTTI) for the year ended December 31, 2018 , and the amounts comprising total OTTI that were recognized in net realized investment gains (losses) and in other comprehensive income (OCI), were as follows: (in millions) TPC Other Subsidiaries TRV Eliminations Consolidated Total OTTI losses $ (1 ) $ — $ — $ — $ (1 ) OTTI losses recognized in net realized investment gains (losses) $ (1 ) $ — $ — $ — $ (1 ) OTTI losses recognized in OCI $ — $ — $ — $ — $ — CONSOLIDATING STATEMENT OF INCOME (Unaudited) For the year ended December 31, 2017 (in millions) TPC Other Subsidiaries TRV Eliminations Consolidated Revenues Premiums $ 17,562 $ 8,121 $ — $ — $ 25,683 Net investment income 1,627 759 24 (13 ) 2,397 Fee income 447 — — — 447 Net realized investment gains (1) 19 131 66 — 216 Other revenues 101 68 — (10 ) 159 Total revenues 19,756 9,079 90 (23 ) 28,902 Claims and expenses Claims and claim adjustment expenses 11,735 5,732 — — 17,467 Amortization of deferred acquisition costs 2,820 1,346 — — 4,166 General and administrative expenses 2,906 1,249 25 (10 ) 4,170 Interest expense 48 — 321 — 369 Total claims and expenses 17,509 8,327 346 (10 ) 26,172 Income (loss) before income taxes 2,247 752 (256 ) (13 ) 2,730 Income tax expense (benefit) 519 290 (130 ) (5 ) 674 Net income of subsidiaries — — 2,190 (2,190 ) — Net income $ 1,728 $ 462 $ 2,064 $ (2,198 ) $ 2,056 ___________________________________________ (1) Total other-than-temporary impairments (OTTI) for the year ended December 31, 2017 , and the amounts comprising total OTTI that were recognized in net realized investment gains and in other comprehensive income (OCI), were as follows: (in millions) TPC Other Subsidiaries TRV Eliminations Consolidated Total OTTI losses $ (4 ) $ (9 ) $ — $ — $ (13 ) OTTI losses recognized in net realized investment gains $ (5 ) $ (9 ) $ — $ — $ (14 ) OTTI gains recognized in OCI $ 1 $ — $ — $ — $ 1
Consolidating Statement of Comprehensive Income (Unaudited) [Table Text Block]	CONSOLIDATING STATEMENT OF COMPREHENSIVE INCOME (Unaudited) For the year ended December 31, 2019 (in millions) TPC Other Subsidiaries TRV Eliminations Consolidated Net income $ 2,212 $ 577 $ 2,622 $ (2,789 ) $ 2,622 Other comprehensive income (loss): Changes in net unrealized gains on investment securities: Having no credit losses recognized in the consolidated statement of income 2,097 893 4 — 2,994 Having credit losses recognized in the consolidated statement of income (2 ) (2 ) — — (4 ) Net changes in benefit plan assets and obligations 1 (3 ) 35 — 33 Net changes in unrealized foreign currency translation 53 64 — — 117 Other comprehensive income before income taxes and other comprehensive income of subsidiaries 2,149 952 39 — 3,140 Income tax expense 441 188 12 — 641 Other comprehensive income, net of taxes, before other comprehensive income of subsidiaries 1,708 764 27 — 2,499 Other comprehensive income of subsidiaries — — 2,472 (2,472 ) — Other comprehensive income 1,708 764 2,499 (2,472 ) 2,499 Comprehensive income $ 3,920 $ 1,341 $ 5,121 $ (5,261 ) $ 5,121 CONSOLIDATING STATEMENT OF COMPREHENSIVE INCOME (Unaudited) For the year ended December 31, 2018 (in millions) TPC Other Subsidiaries TRV Eliminations Consolidated Net income $ 2,110 $ 604 $ 2,523 $ (2,714 ) $ 2,523 Other comprehensive loss: Changes in net unrealized gains on investment securities: Having no credit losses recognized in the consolidated statement of income (1,028 ) (461 ) — — (1,489 ) Having credit losses recognized in the consolidated statement of income (20 ) (7 ) — — (27 ) Net changes in benefit plan assets and obligations 1 (4 ) (53 ) — (56 ) Net changes in unrealized foreign currency translation (144 ) (103 ) — — (247 ) Other comprehensive loss before income taxes and other comprehensive loss of subsidiaries (1,191 ) (575 ) (53 ) — (1,819 ) Income tax benefit (231 ) (101 ) (17 ) — (349 ) Other comprehensive loss, net of taxes, before other comprehensive loss of subsidiaries (960 ) (474 ) (36 ) — (1,470 ) Other comprehensive loss of subsidiaries — — (1,434 ) 1,434 — Other comprehensive loss (960 ) (474 ) (1,470 ) 1,434 (1,470 ) Comprehensive income $ 1,150 $ 130 $ 1,053 $ (1,280 ) $ 1,053 CONSOLIDATING STATEMENT OF COMPREHENSIVE INCOME (Unaudited) For the year ended December 31, 2017 (in millions) TPC Other Subsidiaries TRV Eliminations Consolidated Net income $ 1,728 $ 462 $ 2,064 $ (2,198 ) $ 2,056 Other comprehensive income (loss): Changes in net unrealized gains on investment securities: Having no credit losses recognized in the consolidated statement of income 313 25 (44 ) — 294 Having credit losses recognized in the consolidated statement of income 6 2 — — 8 Net changes in benefit plan assets and obligations (1 ) 8 22 — 29 Net changes in unrealized foreign currency translation 83 108 — — 191 Other comprehensive income (loss) before income taxes and other comprehensive income of subsidiaries 401 143 (22 ) — 522 Income tax expense 98 10 2 — 110 Other comprehensive income (loss), net of taxes, before other comprehensive income of subsidiaries 303 133 (24 ) — 412 Other comprehensive income of subsidiaries — — 436 (436 ) — Other comprehensive income 303 133 412 (436 ) 412 Comprehensive income $ 2,031 $ 595 $ 2,476 $ (2,634 ) $ 2,468
Consolidating Balance Sheet (Unaudited) [Table Text Block]	CONSOLIDATING BALANCE SHEET (Unaudited) At December 31, 2019 (in millions) TPC Other Subsidiaries TRV Eliminations Consolidated Assets Fixed maturities, available for sale, at fair value (amortized cost $65,281) $ 46,805 $ 21,238 $ 91 $ — $ 68,134 Equity securities, at fair value (cost $376) 102 114 209 — 425 Real estate investments 1 962 — — 963 Short-term securities 2,793 760 1,390 — 4,943 Other investments 2,690 728 1 — 3,419 Total investments 52,391 23,802 1,691 — 77,884 Cash 207 287 — — 494 Investment income accrued 428 186 4 — 618 Premiums receivable 5,331 2,578 — — 7,909 Reinsurance recoverables 6,511 1,724 — — 8,235 Ceded unearned premiums 603 86 — — 689 Deferred acquisition costs 2,094 179 — — 2,273 Contractholder receivables 4,606 13 — — 4,619 Goodwill 2,584 1,386 — (9 ) 3,961 Other intangible assets 218 112 — — 330 Investment in subsidiaries — — 30,028 (30,028 ) — Other assets 2,360 419 331 — 3,110 Total assets $ 77,333 $ 30,772 $ 32,054 $ (30,037 ) $ 110,122 Liabilities Claims and claim adjustment expense reserves $ 35,568 $ 16,281 $ — $ — $ 51,849 Unearned premium reserves 10,144 4,460 — — 14,604 Contractholder payables 4,606 13 — — 4,619 Payables for reinsurance premiums 210 153 — — 363 Deferred taxes 272 (170 ) 35 — 137 Debt 693 — 5,865 — 6,558 Other liabilities 4,609 1,236 204 — 6,049 Total liabilities 56,102 21,973 6,104 — 84,179 Shareholders’ equity Common stock (1,750.0 shares authorized; 255.5 shares issued and outstanding) — 585 23,469 (585 ) 23,469 Additional paid-in capital 11,634 7,073 — (18,707 ) — Retained earnings 8,451 823 36,984 (9,281 ) 36,977 Accumulated other comprehensive income 1,146 318 640 (1,464 ) 640 Treasury stock, at cost (522.1 shares) — — (35,143 ) — (35,143 ) Total shareholders’ equity 21,231 8,799 25,950 (30,037 ) 25,943 Total liabilities and shareholders’ equity $ 77,333 $ 30,772 $ 32,054 $ (30,037 ) $ 110,122 CONSOLIDATING BALANCE SHEET (Unaudited) At December 31, 2018 (in millions) TPC Other Subsidiaries TRV Eliminations Consolidated Assets Fixed maturities, available for sale, at fair value (amortized cost $63,601) $ 43,683 $ 19,697 $ 84 $ — $ 63,464 Equity securities, at fair value (cost $382) 105 92 171 — 368 Real estate investments 2 902 — — 904 Short-term securities 1,855 759 1,371 — 3,985 Other investments 2,746 810 1 — 3,557 Total investments 48,391 22,260 1,627 — 72,278 Cash 181 192 — — 373 Investment income accrued 434 187 3 — 624 Premiums receivable 5,089 2,417 — — 7,506 Reinsurance recoverables 5,904 2,466 — — 8,370 Ceded unearned premiums 522 56 — — 578 Deferred acquisition costs 1,930 190 — — 2,120 Deferred taxes 167 302 (24 ) — 445 Contractholder receivables 3,867 918 — — 4,785 Goodwill 2,578 1,368 — (9 ) 3,937 Other intangible assets 224 121 — — 345 Investment in subsidiaries — — 26,993 (26,993 ) — Other assets 2,220 15 669 (32 ) 2,872 Total assets $ 71,507 $ 30,492 $ 29,268 $ (27,034 ) $ 104,233 Liabilities Claims and claim adjustment expense reserves $ 34,093 $ 16,575 $ — $ — $ 50,668 Unearned premium reserves 9,414 4,141 — — 13,555 Contractholder payables 3,867 918 — — 4,785 Payables for reinsurance premiums 169 120 — — 289 Debt 693 32 5,871 (32 ) 6,564 Other liabilities 4,133 849 496 — 5,478 Total liabilities 52,369 22,635 6,367 (32 ) 81,339 Shareholders’ equity Common stock (1,750.0 shares authorized; 263.7 shares issued and 263.6 shares outstanding) — 401 23,144 (401 ) 23,144 Additional paid-in capital 11,634 7,023 — (18,657 ) — Retained earnings 8,065 879 35,211 (8,951 ) 35,204 Accumulated other comprehensive loss (561 ) (446 ) (1,859 ) 1,007 (1,859 ) Treasury stock, at cost (510.9 shares) — — (33,595 ) — (33,595 ) Total shareholders’ equity 19,138 7,857 22,901 (27,002 ) 22,894 Total liabilities and shareholders’ equity $ 71,507 $ 30,492 $ 29,268 $ (27,034 ) $ 104,233
Consolidating Statement of Cash Flows (Unaudited) [Table Text Block]	CONSOLIDATING STATEMENT OF CASH FLOWS (Unaudited) For the year ended December 31, 2019 (in millions) TPC Other Subsidiaries TRV Eliminations Consolidated Cash flows from operating activities Net income $ 2,212 $ 577 $ 2,622 $ (2,789 ) $ 2,622 Net adjustments to reconcile net income to net cash provided by operating activities 1,750 943 (408 ) 298 2,583 Net cash provided by operating activities 3,962 1,520 2,214 (2,491 ) 5,205 Cash flows from investing activities Proceeds from maturities of fixed maturities 4,727 2,107 11 — 6,845 Proceeds from sales of investments: Fixed maturities 1,295 891 1 — 2,187 Equity securities 53 75 12 — 140 Other investments 345 114 — — 459 Purchases of investments: Fixed maturities (7,011 ) (3,686 ) (14 ) — (10,711 ) Equity securities (2 ) (75 ) (17 ) — (94 ) Real estate investments — (107 ) — — (107 ) Other investments (424 ) (73 ) — — (497 ) Net sales (purchases) of short-term securities (939 ) 1 (19 ) — (957 ) Securities transactions in course of settlement 163 (4 ) (1 ) — 158 Other (317 ) (8 ) — — (325 ) Net cash used in investing activities (2,110 ) (765 ) (27 ) — (2,902 ) Cash flows from financing activities Treasury stock acquired — share repurchase authorization — — (1,500 ) — (1,500 ) Treasury stock acquired — net employee share-based compensation — — (48 ) — (48 ) Dividends paid to shareholders — — (844 ) — (844 ) Payment of debt — (32 ) (500 ) 32 (500 ) Issuance of debt — — 492 — 492 Issuance of common stock — employee share options — — 213 — 213 Dividends paid to parent company (1,827 ) (632 ) — 2,459 — Net cash used in financing activities (1,827 ) (664 ) (2,187 ) 2,491 (2,187 ) Effect of exchange rate changes on cash 1 4 — — 5 Net increase in cash 26 95 — — 121 Cash at beginning of year 181 192 — — 373 Cash at end of year $ 207 $ 287 $ — $ — $ 494 Supplemental disclosure of cash flow information Income taxes paid (received) $ 375 $ 131 $ (78 ) $ — $ 428 Interest paid $ 47 $ — $ 291 $ — $ 338 CONSOLIDATING STATEMENT OF CASH FLOWS (Unaudited) For the year ended December 31, 2018 (in millions) TPC Other Subsidiaries TRV Eliminations Consolidated Cash flows from operating activities Net income $ 2,110 $ 604 $ 2,523 $ (2,714 ) $ 2,523 Net adjustments to reconcile net income to net cash provided by operating activities 1,141 605 (363 ) 474 1,857 Net cash provided by operating activities 3,251 1,209 2,160 (2,240 ) 4,380 Cash flows from investing activities Proceeds from maturities of fixed maturities 5,158 1,906 22 — 7,086 Proceeds from sales of investments: Fixed maturities 2,449 1,096 1 — 3,546 Equity securities 65 107 6 — 178 Real estate investments 66 8 — — 74 Other investments 403 108 — — 511 Purchases of investments: Fixed maturities (9,404 ) (4,096 ) (26 ) — (13,526 ) Equity securities (8 ) (99 ) (10 ) — (117 ) Real estate investments (1 ) (73 ) — — (74 ) Other investments (454 ) (83 ) — — (537 ) Net sales (purchases) of short-term securities 895 154 (141 ) — 908 Securities transactions in course of settlement (80 ) 24 — — (56 ) Acquisition, net of cash acquired — (4 ) — — (4 ) Other (310 ) (8 ) — — (318 ) Net cash used in investing activities (1,221 ) (960 ) (148 ) — (2,329 ) Cash flows from financing activities Treasury stock acquired — share repurchase authorization — — (1,270 ) — (1,270 ) Treasury stock acquired — net employee share-based compensation — — (51 ) — (51 ) Dividends paid to shareholders — — (814 ) — (814 ) Payment of debt — — (600 ) — (600 ) Issuance of debt — 18 591 (18 ) 591 Issuance of common stock — employee share options — — 132 — 132 Dividends paid to parent company (2,003 ) (255 ) — 2,258 — Net cash used in financing activities (2,003 ) (237 ) (2,012 ) 2,240 (2,012 ) Effect of exchange rate changes on cash (3 ) (7 ) — — (10 ) Net increase in cash 24 5 — — 29 Cash at beginning of year 157 187 — — 344 Cash at end of year $ 181 $ 192 $ — $ — $ 373 Supplemental disclosure of cash flow information Income taxes paid (received) $ 437 $ 254 $ (283 ) $ — $ 408 Interest paid $ 47 $ — $ 300 $ — $ 347 CONSOLIDATING STATEMENT OF CASH FLOWS (Unaudited) For the year ended December 31, 2017 (in millions) TPC Other Subsidiaries TRV Eliminations Consolidated Cash flows from operating activities Net income $ 1,728 $ 462 $ 2,064 $ (2,198 ) $ 2,056 Net adjustments to reconcile net income to net cash provided by operating activities 1,500 701 (32 ) (77 ) 2,092 Net cash provided by operating activities 3,228 1,163 2,032 (2,275 ) 4,148 Cash flows from investing activities Proceeds from maturities of fixed maturities 6,576 2,168 6 — 8,750 Proceeds from sales of investments: Fixed maturities 1,007 846 1 — 1,854 Equity securities 97 414 254 — 765 Real estate investments — 23 — — 23 Other investments 357 124 — (13 ) 468 Purchases of investments: Fixed maturities (8,513 ) (3,697 ) (40 ) — (12,250 ) Equity securities (68 ) (133 ) (258 ) — (459 ) Real estate investments (1 ) (58 ) — — (59 ) Other investments (444 ) (97 ) — — (541 ) Net sales (purchases) of short-term securities (303 ) (120 ) 397 — (26 ) Securities transactions in course of settlement (55 ) 5 3 — (47 ) Acquisition, net of cash acquired — 25 (477 ) 13 (439 ) Other (244 ) 3 — — (241 ) Net cash used in investing activities (1,591 ) (497 ) (114 ) — (2,202 ) Cash flows from financing activities Treasury stock acquired — share repurchase authorization — — (1,378 ) — (1,378 ) Treasury stock acquired — net employee share-based compensation — — (62 ) — (62 ) Dividends paid to shareholders — — (785 ) — (785 ) Payment of debt — — (657 ) — (657 ) Issuance of debt — 14 789 (14 ) 789 Issuance of common stock — employee share options — — 173 — 173 Dividends paid to parent company (1,624 ) (665 ) — 2,289 — Net cash used in financing activities (1,624 ) (651 ) (1,920 ) 2,275 (1,920 ) Effect of exchange rate changes on cash 3 8 — — 11 Net increase (decrease) in cash 16 23 (2 ) — 37 Cash at beginning of year 141 164 2 — 307 Cash at end of year $ 157 $ 187 $ — $ — $ 344 Supplemental disclosure of cash flow information Income taxes paid (received) $ 481 $ 206 $ (173 ) $ — $ 514 Interest paid $ 47 $ — $ 320 $ — $ 367

Selected Quarterly Financial _2

Selected Quarterly Financial Data (Unaudited) (Table)	12 Months Ended
Selected Quarterly Financial Data (Unaudited) (Table)	Dec. 31, 2019
Quarterly Financial Information Disclosure [Abstract]
Selected Quarterly Financial Data (Unaudited) disclosure [Table Text Block]	2019 (in millions, except per share amounts) First Quarter Second Quarter Third Quarter Fourth Quarter Total Total revenues $ 7,671 $ 7,834 $ 8,013 $ 8,063 $ 31,581 Total expenses 6,704 7,169 7,581 6,989 28,443 Income before income taxes 967 665 432 1,074 3,138 Income tax expense 171 108 36 201 516 Net income $ 796 $ 557 $ 396 $ 873 $ 2,622 Net income per share (1) : Basic $ 3.01 $ 2.11 $ 1.52 $ 3.37 $ 10.01 Diluted 2.99 2.10 1.50 3.35 9.92 2018 (in millions, except per share amounts) First Second Third Fourth Total Total revenues $ 7,286 $ 7,477 $ 7,723 $ 7,796 $ 30,282 Total expenses 6,508 6,846 6,917 7,050 27,321 Income before income taxes 778 631 806 746 2,961 Income tax expense 109 107 97 125 438 Net income $ 669 $ 524 $ 709 $ 621 $ 2,523 Net income per share (1) : Basic $ 2.45 $ 1.93 $ 2.65 $ 2.33 $ 9.37 Diluted 2.42 1.92 2.62 2.32 9.28 ___________________________________________ (1) Due to the use of an average number of shares for each quarter, the sum of the quarterly earnings per share may not equal the total earnings per share for the full year.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Details) - Updated Guidance - USD ($)	Jan. 01, 2018	Dec. 31, 2018	Dec. 31, 2019	Mar. 31, 2019	Jan. 01, 2019	Dec. 31, 2017
New Accounting Pronouncements
Operating lease liability			$ 380,000,000
Accumulated Other Comprehensive Income (Loss) [Member]
New Accounting Pronouncements
Cumulative effect adjustment	$ (22,000,000)					$ (22,000,000)
Reclassification of certain tax effects from adoption of updated accounting guidance	(24,000,000)	$ (24,000,000)
Retained earnings [Member]
New Accounting Pronouncements
Cumulative effect adjustment						$ 22,000,000
Reclassification of certain tax effects from adoption of updated accounting guidance		$ 24,000,000
Accounting Standards Update 2016-01 [Member] \| Accumulated Other Comprehensive Income (Loss) [Member]
New Accounting Pronouncements
Cumulative effect adjustment	(22,000,000)
Accounting Standards Update 2016-01 [Member] \| Retained earnings [Member]
New Accounting Pronouncements
Cumulative effect adjustment	22,000,000
Accounting Standards Update 2018-02 [Member] \| Accumulated Other Comprehensive Income (Loss) [Member]
New Accounting Pronouncements
Reclassification of certain tax effects from adoption of updated accounting guidance	(24,000,000)
Accounting Standards Update 2018-02 [Member] \| Retained earnings [Member]
New Accounting Pronouncements
Reclassification of certain tax effects from adoption of updated accounting guidance	$ 24,000,000
Accounting Standards Update 2016-02 [Member]
New Accounting Pronouncements
Right-of-use asset				$ 320,000,000
Operating lease liability				$ 384,000,000
Accounting Standards Update 2016-02 [Member] \| Retained earnings [Member]
New Accounting Pronouncements
Cumulative effect adjustment					$ 0

Summary of Significant Accoun_4

Summary of Significant Accounting Policies (Details) - Revenue from Contracts with Customers - Accounting Standards Update 2014-09 [Member] $ in Millions	12 Months Ended
	Dec. 31, 2018USD ($)
Revenues within scope of updated accounting guidance
Revenues within scope of updated accounting guidance	$ 171
Revenues within scope of updated accounting guidance, as a percentage of total revenues (less than)	1.00%

Summary of Significant Accoun_5

Summary of Significant Accounting Policies (Details) - Credit Losses - USD ($) $ in Millions	Jan. 01, 2020	Dec. 31, 2017
Retained earnings [Member]
New Accounting Pronouncements
Cumulative effect adjustment		$ 22
Subsequent event [Member] \| Forecast [Member] \| Accounting Standards Update 2016-13 [Member] \| Allowance for uncollectible reinsurance [Member]
New Accounting Pronouncements
Cumulative effect adjustment	$ 43
Subsequent event [Member] \| Forecast [Member] \| Accounting Standards Update 2016-13 [Member] \| Retained earnings [Member]
New Accounting Pronouncements
Cumulative effect adjustment	$ (43)

Summary of Significant Accoun_6

Summary of Significant Accounting Policies Summary of Significant Accounting Policies (Details) - Policy Details	12 Months Ended
	Dec. 31, 2019
Accounting Policies [Abstract]
Maximum useful life for buildings held in real estate investments	39 years
Maximum original maturity of short-term securities	1 year
Availability of financial information provided by private equity and real estate partnerships following the date of the reporting, maximum	3 months
Availability of financial information provided by hedge funds following the date of the reporting	1 month
Estimated recovery time for securities for which the issuer is in bankruptcy	12 months
Estimated recovery time for securities for which the issuer is financially troubled but not in bankruptcy	24 months

Summary of Significant Accoun_7

Summary of Significant Accounting Policies (Details) - Additional Details $ in Millions	12 Months Ended
	Dec. 31, 2019USD ($)businessessegment	Dec. 31, 2018USD ($)	Dec. 31, 2017
Accounting Policies [Abstract]
Minimum collateral provided by borrowers of securities, as a percentage of the market value of the loaned securities plus accrued interest	102.00%
Number of reporting units for which the Company performs a review of goodwill held \| segment	3
Number of operating segments \| segment	3
Number of reportable segments \| segment	3
Liability for guaranty fund and other insurance-related assessments \| $	$ 184	$ 217
Recoverables for liability for guaranty fund and other insurance-related assessments \| $	$ 13	$ 16
Minimum expected payment period for loss-based assessments and recoveries	1 year	1 year
Net written premiums for participating dividend policies as a percent of total Company net written premiums	1.00%	1.00%	1.00%
Liability accrued for policyholder dividends \| $	$ 71	$ 72
Percentage of capital provided by International for its syndicate at Lloyd's	100.00%
Number of principal business units through which the Company's syndicate at Lloyd's writes business \| businesses	6

Summary of Significant Accoun_8

Summary of Significant Accounting Policies (Details) - Equity Method Investment	Dec. 31, 2019
Junto - Brazilian joint venture [Member]
Equity method investment
Percent of common stock owned	49.50%
Junto Holding Latam S.A. [Member]
Equity method investment
Percent of common stock owned	49.50%

Segment Information (Details)

Segment Information (Details) $ in Millions		3 Months Ended								12 Months Ended
Segment Information (Details) $ in Millions		Dec. 31, 2019USD ($)	Sep. 30, 2019USD ($)	Jun. 30, 2019USD ($)	Mar. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Sep. 30, 2018USD ($)	Jun. 30, 2018USD ($)	Mar. 31, 2018USD ($)	Dec. 31, 2019USD ($)segment	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)
Segment reporting information
Number of reportable segments \| segment										3
Premiums										$ 28,272	$ 27,059	$ 25,683
Net investment income										2,468	2,474	2,397
Fee income										459	432	447
Other revenues										269	203	159
Income tax expense (benefit)		$ 201	$ 36	$ 108	$ 171	$ 125	$ 97	$ 107	$ 109	516	438	674
Net realized investment gains	[1]									113	114	216
Total revenues		8,063	8,013	7,834	7,671	7,796	7,723	7,477	7,286	31,581	30,282	28,902
Core income (loss)										2,537	2,430	2,043
Net realized investment gains, net of tax										85	93	142
Impact of Tax Cuts and Jobs Act of 2017 at enactment												(129)
Net income		$ 873	$ 396	$ 557	$ 796	$ 621	$ 709	$ 524	$ 669	2,622	2,523	2,056
Domestic [Member]
Segment reporting information
Total revenues										29,638	28,418	27,253
International [Member]
Segment reporting information
Total revenues										1,943	1,864	1,649
Reportable segments [Member]
Segment reporting information
Premiums										28,272	27,059	25,683
Net investment income										2,468	2,474	2,397
Fee income										459	432	447
Other revenues										268	201	153
Total segment revenues										31,467	30,166	28,680
Amortization and depreciation										5,357	5,177	4,972
Income tax expense (benefit)										569	499	612
Core income (loss)										2,834	2,728	2,297
Reportable segments [Member] \| Business Insurance [Member]
Segment reporting information
Premiums										15,300	14,722	14,146
Net investment income										1,816	1,833	1,786
Fee income										437	412	430
Other revenues										155	112	69
Total segment revenues										17,708	17,079	16,431
Amortization and depreciation										3,037	2,943	2,852
Income tax expense (benefit)										223	259	448
Core income (loss)										1,392	1,638	1,613
Reportable segments [Member] \| Business Insurance [Member] \| Domestic [Member]
Segment reporting information
Premiums										14,233	13,657	13,143
Reportable segments [Member] \| Business Insurance [Member] \| Domestic [Member] \| Workers' compensation [Member]
Segment reporting information
Premiums										3,829	3,899	3,962
Reportable segments [Member] \| Business Insurance [Member] \| Domestic [Member] \| Automobile [Member]
Segment reporting information
Premiums										2,632	2,388	2,132
Reportable segments [Member] \| Business Insurance [Member] \| Domestic [Member] \| Commercial property [Member]
Segment reporting information
Premiums										1,937	1,828	1,775
Reportable segments [Member] \| Business Insurance [Member] \| Domestic [Member] \| General liability [Member]
Segment reporting information
Premiums										2,342	2,181	2,047
Reportable segments [Member] \| Business Insurance [Member] \| Domestic [Member] \| Commercial multi-peril [Member]
Segment reporting information
Premiums										3,453	3,333	3,198
Reportable segments [Member] \| Business Insurance [Member] \| Domestic [Member] \| Other [Member]
Segment reporting information
Premiums										40	28	29
Reportable segments [Member] \| Business Insurance [Member] \| International [Member]
Segment reporting information
Premiums										1,067	1,065	1,003
Reportable segments [Member] \| Bond & Specialty Insurance [Member]
Segment reporting information
Premiums										2,565	2,420	2,307
Net investment income										233	233	228
Other revenues										26	23	24
Total segment revenues										2,824	2,676	2,559
Amortization and depreciation										533	515	493
Income tax expense (benefit)										151	198	208
Core income (loss)										618	793	556
Reportable segments [Member] \| Bond & Specialty Insurance [Member] \| Domestic [Member]
Segment reporting information
Premiums										2,334	2,216	2,126
Reportable segments [Member] \| Bond & Specialty Insurance [Member] \| Domestic [Member] \| General liability [Member]
Segment reporting information
Premiums										1,082	1,004	962
Reportable segments [Member] \| Bond & Specialty Insurance [Member] \| Domestic [Member] \| Fidelity and surety [Member]
Segment reporting information
Premiums										1,036	1,017	977
Reportable segments [Member] \| Bond & Specialty Insurance [Member] \| Domestic [Member] \| Other [Member]
Segment reporting information
Premiums										216	195	187
Reportable segments [Member] \| Bond & Specialty Insurance [Member] \| International [Member]
Segment reporting information
Premiums										231	204	181
Reportable segments [Member] \| Personal Insurance [Member]
Segment reporting information
Premiums										10,407	9,917	9,230
Net investment income										419	408	383
Fee income										22	20	17
Other revenues										87	66	60
Total segment revenues										10,935	10,411	9,690
Amortization and depreciation										1,787	1,719	1,627
Income tax expense (benefit)										195	42	(44)
Core income (loss)										824	297	128
Reportable segments [Member] \| Personal Insurance [Member] \| Domestic [Member]
Segment reporting information
Premiums										9,704	9,232	8,598
Reportable segments [Member] \| Personal Insurance [Member] \| Domestic [Member] \| Automobile [Member]
Segment reporting information
Premiums										5,311	5,097	4,655
Reportable segments [Member] \| Personal Insurance [Member] \| Domestic [Member] \| Homeowners and Other [Member]
Segment reporting information
Premiums										4,393	4,135	3,943
Reportable segments [Member] \| Personal Insurance [Member] \| International [Member]
Segment reporting information
Premiums										703	685	632
Other [Member]
Segment reporting information
Other revenues										1	2	6
Core income (loss)										(297)	(298)	(254)
After-tax interest expense										$ 272	$ 278	$ 240

[1]	Total other-than-temporary impairment (OTTI) losses were $(3) million , $(1) million and $(13) million for the years ended December 31, 2019 , 2018 and 2017 , respectively. Of total OTTI, credit losses of $(4) million , $(1) million and $(14) million for the years ended December 31, 2019 , 2018 and 2017 , respectively, were recognized in net realized investment gains. In addition, unrealized gains (losses) from other changes in total OTTI of $1 million , $0 million and $1 million for the years ended December 31, 2019 , 2018 and 2017 , respectively, were recognized in other comprehensive income (loss) as part of changes in net unrealized gains (losses) on investment securities having credit losses recognized in the consolidated statement of income.

Segment Information (Details) -

Segment Information (Details) - Net Written Premiums - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Segment reporting information
Net written premiums	$ 29,151	$ 27,708	$ 26,219
Business Insurance [Member]
Segment reporting information
Net written premiums	15,629	14,956	14,270
Business Insurance [Member] \| Domestic [Member]
Segment reporting information
Net written premiums	14,557	13,872	13,257
Business Insurance [Member] \| Domestic [Member] \| Select Accounts [Member]
Segment reporting information
Net written premiums	2,911	2,828	2,800
Business Insurance [Member] \| Domestic [Member] \| Middle Market [Member]
Segment reporting information
Net written premiums	8,630	8,214	7,756
Business Insurance [Member] \| Domestic [Member] \| National Accounts [Member]
Segment reporting information
Net written premiums	1,051	1,025	1,010
Business Insurance [Member] \| Domestic [Member] \| National Property and Other [Member]
Segment reporting information
Net written premiums	1,965	1,805	1,691
Business Insurance [Member] \| International [Member]
Segment reporting information
Net written premiums	1,072	1,084	1,013
Bond & Specialty Insurance [Member]
Segment reporting information
Net written premiums	2,739	2,528	2,359
Bond & Specialty Insurance [Member] \| Domestic [Member]
Segment reporting information
Net written premiums	2,471	2,290	2,160
Bond & Specialty Insurance [Member] \| Domestic [Member] \| Management Liability [Member]
Segment reporting information
Net written premiums	1,605	1,455	1,367
Bond & Specialty Insurance [Member] \| Domestic [Member] \| Surety [Member]
Segment reporting information
Net written premiums	866	835	793
Bond & Specialty Insurance [Member] \| International [Member]
Segment reporting information
Net written premiums	268	238	199
Personal Insurance [Member]
Segment reporting information
Net written premiums	10,783	10,224	9,590
Personal Insurance [Member] \| Domestic [Member]
Segment reporting information
Net written premiums	10,076	9,516	8,940
Personal Insurance [Member] \| Domestic [Member] \| Total Agency [Member]
Segment reporting information
Net written premiums	9,664	9,120	8,579
Personal Insurance [Member] \| Domestic [Member] \| Agency Automobile [Member]
Segment reporting information
Net written premiums	5,124	4,972	4,646
Personal Insurance [Member] \| Domestic [Member] \| Agency Homeowners and Other [Member]
Segment reporting information
Net written premiums	4,540	4,148	3,933
Personal Insurance [Member] \| Domestic [Member] \| Direct-to-Consumer [Member]
Segment reporting information
Net written premiums	412	396	361
Personal Insurance [Member] \| International [Member]
Segment reporting information
Net written premiums	$ 707	$ 708	$ 650

Segment Information (Details)_2

Segment Information (Details) - Assets by Segment - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Assets by segment
Total assets	$ 110,122	$ 104,233
Reportable segments [Member]
Assets by segment
Total assets	109,510	103,601
Reportable segments [Member] \| Business Insurance [Member]
Assets by segment
Total assets	83,896	78,965
Reportable segments [Member] \| Bond & Specialty Insurance [Member]
Assets by segment
Total assets	8,599	8,693
Reportable segments [Member] \| Personal Insurance [Member]
Assets by segment
Total assets	17,015	15,943
Other assets [Member]
Assets by segment
Total assets	$ 612	$ 632

Segment Information (Details)_3

Segment Information (Details) - Enterprise-Wide Disclosures - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenues based on location
Benchmark percentage of revenue transactions from a single customer									10.00%	10.00%	10.00%
Total revenues	$ 8,063	$ 8,013	$ 7,834	$ 7,671	$ 7,796	$ 7,723	$ 7,477	$ 7,286	$ 31,581	$ 30,282	$ 28,902
United States [Member]
Revenues based on location
Total revenues									29,638	28,418	27,253
Non-U.S. [Member]
Revenues based on location
Total revenues									1,943	1,864	1,649
Canada [Member]
Revenues based on location
Total revenues									1,371	1,293	1,232
Other Non-U.S. [Member]
Revenues based on location
Total revenues									$ 572	$ 571	$ 417

Investments (Details) - Fixed M

Investments (Details) - Fixed Maturities - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Investment disclosure details
Fixed maturities, amortized cost	$ 65,281	$ 63,601
Gross unrealized gains	2,882	712
Gross unrealized losses	29	849
Fixed maturities, at fair value	68,134	63,464
U.S. Treasury securities and obligations of U.S. government and government agencies and authorities [Member]
Investment disclosure details
Fixed maturities, amortized cost	2,076	2,076
Gross unrealized gains	19	4
Gross unrealized losses	0	16
Fixed maturities, at fair value	2,095	2,064
Obligations of states, municipalities and political subdivisions [Member]
Investment disclosure details
Fixed maturities, amortized cost	28,356	28,329
Gross unrealized gains	1,567	489
Gross unrealized losses	6	207
Fixed maturities, at fair value	29,917	28,611
Obligations of states, municipalities and political subdivisions, local general obligation [Member]
Investment disclosure details
Fixed maturities, amortized cost	15,490	14,473
Gross unrealized gains	829	219
Gross unrealized losses	4	120
Fixed maturities, at fair value	16,315	14,572
Obligations of states, municipalities and political subdivisions, revenue [Member]
Investment disclosure details
Fixed maturities, amortized cost	9,731	9,755
Gross unrealized gains	586	172
Gross unrealized losses	2	74
Fixed maturities, at fair value	10,315	9,853
Obligations of states, municipalities and political subdivisions, state general obligation [Member]
Investment disclosure details
Fixed maturities, amortized cost	1,167	1,329
Gross unrealized gains	64	18
Gross unrealized losses	0	13
Fixed maturities, at fair value	1,231	1,334
Obligations of states, municipalities and political subdivisions, pre-refunded [Member]
Investment disclosure details
Fixed maturities, amortized cost	1,968	2,772
Gross unrealized gains	88	80
Gross unrealized losses	0	0
Fixed maturities, at fair value	2,056	2,852
Debt securities issued by foreign governments [Member]
Investment disclosure details
Fixed maturities, amortized cost	1,167	1,255
Gross unrealized gains	8	7
Gross unrealized losses	2	5
Fixed maturities, at fair value	1,173	1,257
Mortgage-backed securities, collateralized mortgage obligations and pass-through securities [Member]
Investment disclosure details
Fixed maturities, amortized cost	3,192	2,557
Gross unrealized gains	91	54
Gross unrealized losses	3	38
Fixed maturities, at fair value	3,280	2,573
All other corporate bonds [Member]
Investment disclosure details
Fixed maturities, amortized cost	30,442	29,307
Gross unrealized gains	1,195	156
Gross unrealized losses	18	583
Fixed maturities, at fair value	31,619	28,880
Redeemable preferred stock [Member]
Investment disclosure details
Fixed maturities, amortized cost	48	77
Gross unrealized gains	2	2
Gross unrealized losses	0	0
Fixed maturities, at fair value	$ 50	$ 79

Investments Investments (Detail

Investments Investments (Details) - Contractual Maturities - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Investments [Abstract]
Fixed maturities, due in one year or less, amortized cost	$ 3,738
Fixed maturities, due after 1 year through 5 years, amortized cost	17,729
Fixed maturities, due after 5 years through 10 years, amortized cost	17,262
Fixed maturities, due after 10 years, amortized cost	23,360
Fixed maturities excluding mortgage-backed securities, collateralized mortgage obligations and pass-through securities, amortized cost	62,089
Mortgage-backed securities, collateralized mortgage obligations and pass-through securities, amortized cost	3,192
Fixed maturities, amortized cost	65,281	$ 63,601
Fixed maturities, due in one year or less, fair value	3,760
Fixed maturities, due after 1 year through 5 years, fair value	18,241
Fixed maturities, due after 5 years through 10 years, fair value	18,215
Fixed maturities, due after 10 years, fair value	24,638
Fixed maturities excluding mortgage-backed securities, collateralized mortgage obligations and pass-through securities, fair value	64,854
Mortgage-backed securities, collateralized mortgage obligations and pass-through securities, fair value	3,280
Fixed maturities, at fair value	$ 68,134	$ 63,464

Investments (Details) - Fixed_2

Investments (Details) - Fixed Maturities Narrative - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Investment disclosure details
Fixed maturities, at fair value	$ 68,134	$ 63,464
Securities on loan as part of a tri-party lending agreement	404	367
Proceeds from sales of fixed maturities classified as available for sale	2,187	3,546	$ 1,854
Gross realized gains on sales of fixed maturities	67	51	42
Gross realized losses on sales of fixed maturities	8	18	$ 38
Insurance subsidiaries' securities on deposit at financial institutions in certain states pursuant to the respective states' insurance regulatory requirements	4,340	4,230
Fair value of funds deposited with third parties to be used as collateral to secure various liabilities on behalf of insureds, cedants and other creditors	54	37
Fair value of other investments pledged as collateral securing outstanding letters of credit	1	1
Subsidiary [Member]
Investment disclosure details
Fair value of owned securities pledged into a Lloyd's trust account to support capital requirements for the Company's operations at Lloyd's	173	115
TRV [Member]
Investment disclosure details
Fixed maturities, at fair value	91	84
Fair value of owned securities pledged into a Lloyd's trust account to support capital requirements for the Company's operations at Lloyd's	34	33
Obligations of states, municipalities and political subdivisions, pre-refunded [Member]
Investment disclosure details
Fixed maturities, at fair value	2,056	2,852
Mortgage-backed securities, collateralized mortgage obligations and pass-through securities [Member]
Investment disclosure details
Fixed maturities, at fair value	3,280	2,573
Residential mortgage-backed pass-through securities classified as available-for-sale, GNMA, FNMA, FHLMC and Canadian Government [Member]
Investment disclosure details
Fixed maturities, at fair value	1,520	859
Residential collateralized mortgage obligations [Member]
Investment disclosure details
Fixed maturities, at fair value	$ 1,760	$ 1,710
Percent guaranteed by or fully collateralized by securities issued by GNMA, FNMA or FHLMC	54.00%	52.00%
Non-guaranteed residential collateralized mortgage obligations [Member]
Investment disclosure details
Fixed maturities, at fair value	$ 816	$ 828
Commercial mortgage-backed securities [Member]
Investment disclosure details
Fixed maturities, at fair value	1,510	1,220
Commercial mortgage-backed securities, containing guarantees by the U.S. government or a government-sponsored enterprise [Member]
Investment disclosure details
Fixed maturities, at fair value	559	458
Commercial mortgage-backed securities, non-guaranteed securities [Member]
Investment disclosure details
Fixed maturities, at fair value	$ 950	$ 759

Investments (Details) - Equity

Investments (Details) - Equity Securities - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Investment disclosure details
Equity securities, cost	$ 376	$ 382
Gross gains	52	10
Gross losses	3	24
Equity securities, at fair value	425	368
Net recognized gains (losses) on equity securities still held	61	(29)
Public common stock [Member]
Investment disclosure details
Equity securities, cost	341	338
Gross gains	45	2
Gross losses	3	24
Equity securities, at fair value	383	316
Non-redeemable preferred stock [Member]
Investment disclosure details
Equity securities, cost	35	44
Gross gains	7	8
Gross losses	0	0
Equity securities, at fair value	$ 42	$ 52

Investments (Details) - Availab

Investments (Details) - Available for Sale Equity Securities $ in Millions	12 Months Ended
	Dec. 31, 2017USD ($)
Investment disclosure details
Proceeds from sales of equity securities classified as available for sale	$ 765
Equity securities [Member]
Investment disclosure details
Gross realized gains	239
Gross realized losses	$ 3

Investments (Details) - Additio

Investments (Details) - Additional Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Investments [Abstract]
Proceeds from sales of real estate investments	$ 0	$ 74	$ 23
Gross gains on sales of real estate investments		23	10
Gross losses on sales of real estate investments		0	$ 0
Accumulated depreciation on real estate held for investment purposes	422	383
Future minimum rental income expected on operating leases relating to the Company's real estate properties for 2020	110
Future minimum rental income expected on operating leases relating to the Company's real estate properties for 2021	102
Future minimum rental income expected on operating leases relating to the Company's real estate properties for 2022	85
Future minimum rental income expected on operating leases relating to the Company's real estate properties for 2023	61
Future minimum rental income expected on operating leases relating to the Company's real estate properties for 2024	45
Future minimum rental income expected on operating leases relating to the Company's real estate properties for 2025 and thereafter	$ 71
Combined average days to maturity of short-term securities (in days)	54 days
Amortized cost of short-term securities (which approximates fair value)	$ 4,943	$ 3,985
Minimum percentage of equity interest that must be held by the Company in order for the investment in a VIE to be considered significant	20.00%

Investments (Details) - Unreali

Investments (Details) - Unrealized Losses - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Investment disclosure details
Continuous unrealized loss position, less than 12 months, fair value	$ 2,900	$ 19,036
Continuous unrealized loss position, less than 12 months, gross unrealized losses	19	399
Continuous unrealized loss position, 12 months or longer, fair value	1,145	12,579
Continuous unrealized loss position, 12 months or longer, gross unrealized losses	10	450
Continuous unrealized loss position, total, fair value	4,045	31,615
Continuous unrealized loss position, total, gross unrealized losses	29	849
Unrealized losses for fixed maturity investments for which fair value is less than 80% of amortized cost, total	0
U.S. Treasury securities and obligations of U.S. government and government agencies and authorities [Member]
Investment disclosure details
Continuous unrealized loss position, less than 12 months, fair value	5	484
Continuous unrealized loss position, less than 12 months, gross unrealized losses	0	5
Continuous unrealized loss position, 12 months or longer, fair value	193	1,011
Continuous unrealized loss position, 12 months or longer, gross unrealized losses	0	11
Continuous unrealized loss position, total, fair value	198	1,495
Continuous unrealized loss position, total, gross unrealized losses	0	16
Obligations of states, municipalities and political subdivisions [Member]
Investment disclosure details
Continuous unrealized loss position, less than 12 months, fair value	668	5,241
Continuous unrealized loss position, less than 12 months, gross unrealized losses	6	82
Continuous unrealized loss position, 12 months or longer, fair value	12	3,298
Continuous unrealized loss position, 12 months or longer, gross unrealized losses	0	125
Continuous unrealized loss position, total, fair value	680	8,539
Continuous unrealized loss position, total, gross unrealized losses	6	207
Debt securities issued by foreign governments [Member]
Investment disclosure details
Continuous unrealized loss position, less than 12 months, fair value	257	96
Continuous unrealized loss position, less than 12 months, gross unrealized losses	1	0
Continuous unrealized loss position, 12 months or longer, fair value	147	328
Continuous unrealized loss position, 12 months or longer, gross unrealized losses	1	5
Continuous unrealized loss position, total, fair value	404	424
Continuous unrealized loss position, total, gross unrealized losses	2	5
Mortgage-backed securities, collateralized mortgage obligations and pass-through securities [Member]
Investment disclosure details
Continuous unrealized loss position, less than 12 months, fair value	399	593
Continuous unrealized loss position, less than 12 months, gross unrealized losses	2	9
Continuous unrealized loss position, 12 months or longer, fair value	131	1,070
Continuous unrealized loss position, 12 months or longer, gross unrealized losses	1	29
Continuous unrealized loss position, total, fair value	530	1,663
Continuous unrealized loss position, total, gross unrealized losses	3	38
All other corporate bonds [Member]
Investment disclosure details
Continuous unrealized loss position, less than 12 months, fair value	1,571	12,622
Continuous unrealized loss position, less than 12 months, gross unrealized losses	10	303
Continuous unrealized loss position, 12 months or longer, fair value	662	6,872
Continuous unrealized loss position, 12 months or longer, gross unrealized losses	8	280
Continuous unrealized loss position, total, fair value	2,233	19,494
Continuous unrealized loss position, total, gross unrealized losses	$ 18	$ 583

Investments (Details) - Impairm

Investments (Details) - Impairment Charges - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Investment Information
Fixed maturities impairment charges	$ 4	$ 1
Other investments impairment charges	0	0
Total investments impairment charges	4	1
Impairment charges			$ 14
Fixed maturities [Member]
Investment Information
Impairment charges			4
U.S. Treasury securities and obligations of U.S. government and government agencies and authorities [Member]
Investment Information
Fixed maturities impairment charges	0	0
Impairment charges			0
Obligations of states, municipalities and political subdivisions [Member]
Investment Information
Fixed maturities impairment charges	0	0
Impairment charges			0
Debt securities issued by foreign governments [Member]
Investment Information
Fixed maturities impairment charges	0	0
Impairment charges			0
Mortgage-backed securities, collateralized mortgage obligations and pass-through securities [Member]
Investment Information
Fixed maturities impairment charges	0	0
Impairment charges			0
All other corporate bonds [Member]
Investment Information
Fixed maturities impairment charges	4	1
Impairment charges			4
Redeemable preferred stock [Member]
Investment Information
Fixed maturities impairment charges	$ 0	$ 0
Impairment charges			0
Equity securities [Member]
Investment Information
Impairment charges			9
Public common stock [Member]
Investment Information
Impairment charges			9
Non-redeemable preferred stock [Member]
Investment Information
Impairment charges			0
Other investments [Member]
Investment Information
Impairment charges			$ 1

Investments (Details) - OTTI Ro

Investments (Details) - OTTI Rollforward - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Roll-forward of the credit losses on fixed maturities recognized in the consolidated statement of income for which a portion of the other-than-temporary impairment was recognized in other comprehensive income (loss) [Roll Forward]
Cumulative OTTI credit losses recognized for securities held, beginning of period	$ 57	$ 75
Additions for OTTI Securities Where No Credit Losses Were Previously Recognized	0	0
Additions for OTTI Securities Where Credit Losses Have Been Previously Recognized	0	0
Reductions Due to Sales/Defaults of Credit- Impaired Securities	(58)	(30)
Adjustments to Book Value of Credit- Impaired Securities due to Changes in Cash Flows	13	12
Cumulative OTTI credit losses recognized for securities still held, end of period	12	57
Mortgage-backed securities, collateralized mortgage obligations and pass-through securities [Member]
Roll-forward of the credit losses on fixed maturities recognized in the consolidated statement of income for which a portion of the other-than-temporary impairment was recognized in other comprehensive income (loss) [Roll Forward]
Cumulative OTTI credit losses recognized for securities held, beginning of period	15	29
Additions for OTTI Securities Where No Credit Losses Were Previously Recognized	0	0
Additions for OTTI Securities Where Credit Losses Have Been Previously Recognized	0	0
Reductions Due to Sales/Defaults of Credit- Impaired Securities	(9)	(18)
Adjustments to Book Value of Credit- Impaired Securities due to Changes in Cash Flows	3	4
Cumulative OTTI credit losses recognized for securities still held, end of period	9	15
All other corporate bonds [Member]
Roll-forward of the credit losses on fixed maturities recognized in the consolidated statement of income for which a portion of the other-than-temporary impairment was recognized in other comprehensive income (loss) [Roll Forward]
Cumulative OTTI credit losses recognized for securities held, beginning of period	42	46
Additions for OTTI Securities Where No Credit Losses Were Previously Recognized	0	0
Additions for OTTI Securities Where Credit Losses Have Been Previously Recognized	0	0
Reductions Due to Sales/Defaults of Credit- Impaired Securities	(49)	(12)
Adjustments to Book Value of Credit- Impaired Securities due to Changes in Cash Flows	10	8
Cumulative OTTI credit losses recognized for securities still held, end of period	$ 3	$ 42

Investments Investments (Deta_2

Investments Investments (Details) - Concentrations and Credit Quality - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Investment disclosure details
Fixed maturities, at fair value	$ 68,134	$ 63,464
Below investment grade [Member]
Investment disclosure details
Fixed maturities, at fair value	1,460	1,480
U.S. Treasury securities and obligations of U.S. government and government agencies and authorities [Member]
Investment disclosure details
Fixed maturities, at fair value	$ 2,095	$ 2,064
Credit Concentration Risk [Member] \| Shareholders' equity, total [Member] \| U.S. Treasury securities and obligations of U.S. government and government agencies and authorities [Member] \| Minimum [Member]
Investment disclosure details
Concentration risk as a percentage of shareholders' equity	5.00%	5.00%

Investments (Details) - Net Inv

Investments (Details) - Net Investment Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Net investment income
Gross investment income	$ 2,508	$ 2,513	$ 2,435
Investment expenses	40	39	38
Net investment income	2,468	2,474	2,397
Fixed maturities [Member]
Net investment income
Gross investment income	2,070	1,980	1,895
Equity securities [Member]
Net investment income
Gross investment income	15	16	28
Short-term securities [Member]
Net investment income
Gross investment income	105	92	62
Real estate [Member]
Net investment income
Gross investment income	55	48	44
Other investments [Member]
Net investment income
Gross investment income	$ 263	$ 377	$ 406

Investments (Details) - Net Unr

Investments (Details) - Net Unrealized Investment Gains - USD ($) $ in Millions	Jan. 01, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Changes in net unrealized investment gains [Roll Forward]
Changes in net unrealized investment gains (losses)		$ 3,140	$ (1,819)	$ 522
Income tax expense (benefit)		641	(349)	110
Change in net unrealized gains (losses) on investment securities, net of tax		2,499	(1,470)	412
Balance, beginning of year		(1,859)
Balance, end of year		640	(1,859)
Total net unrealized gains on investment securities (after-tax)				1,110
Net unrealized gains on investment securities reported in accumulated other comprehensive income (after-tax)				954
Adjustment reported in retained earnings due to the enactment of the Tax Cuts and Jobs Act of 2017				158
Accumulated Other Comprehensive Income (Loss) [Member]
Changes in net unrealized investment gains [Roll Forward]
Changes in net unrealized investment gains (losses)		3,140	(1,819)	522
Income tax expense (benefit)		641	(349)	110
Change in net unrealized gains (losses) on investment securities, net of tax		2,499	(1,470)	412
Cumulative effect of adoption of updated accounting guidance for equity financial instruments	$ (22)			(22)
Reclassification of certain tax effects from adoption of updated accounting guidance	(24)		(24)
Changes in Net Unrealized Gains on Investment Securities [Member]
Changes in net unrealized investment gains [Roll Forward]
Changes in net unrealized investment gains (losses)		2,990	(1,516)	302
Income tax expense (benefit)		631	(319)	78
Change in net unrealized gains (losses) on investment securities, net of tax		2,359	(1,197)	224
Cumulative effect of adoption of updated accounting guidance for equity financial instruments			(22)
Reclassification of certain tax effects from adoption of updated accounting guidance			152
Balance, beginning of year	$ 954	(113)	954	730
Balance, end of year		2,246	(113)	954
Changes in Net Unrealized Gains on Investment Securities [Member] \| Fixed maturities [Member]
Changes in net unrealized investment gains [Roll Forward]
Changes in net unrealized investment gains (losses)		2,990	(1,515)	513
Changes in Net Unrealized Gains on Investment Securities [Member] \| Equity securities [Member]
Changes in net unrealized investment gains [Roll Forward]
Changes in net unrealized investment gains (losses)		0	0	(215)
Changes in Net Unrealized Gains on Investment Securities [Member] \| Other investments [Member]
Changes in net unrealized investment gains [Roll Forward]
Changes in net unrealized investment gains (losses)		$ 0	$ (1)	$ 4

Investments Investments (Deta_3

Investments Investments (Details) - Derivatives - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Futures [Member] \| U.S. Treasury notes contracts [Member]
Derivatives
Notional value of open contracts	$ 0	$ 0

Fair Value Measurements (Detail

Fair Value Measurements (Details) - Additional Information - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Percent of fixed maturities for which a pricing service estimates fair value	99.00%	99.00%
Percent change in monthly price at which securities are further evaluated	10.00%
Fair value of the fixed maturities for which the Company used an internal pricing matrix	$ 73	$ 82
Fair value of the fixed maturities for which the Company received a broker quote	28	104
Estimated fair value of put/call option	$ 8	$ 10

Fair Value Measurements (Deta_2

Fair Value Measurements (Details) - Fair Value Hierarchy - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured
Estimated fair value of put/call option reported in other liabilities	$ 8	$ 10
Recurring basis [Member]
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured
Total invested assets measured on a recurring basis	68,595	63,884
Other liabilities measured on a recurring basis	8	10
Recurring basis [Member] \| Fixed maturities [Member]
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured
Total invested assets measured on a recurring basis	68,134	63,464
Recurring basis [Member] \| U.S. Treasury securities and obligations of U.S. government and government agencies and authorities [Member]
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured
Total invested assets measured on a recurring basis	2,095	2,064
Recurring basis [Member] \| Obligations of states, municipalities and political subdivisions [Member]
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured
Total invested assets measured on a recurring basis	29,917	28,611
Recurring basis [Member] \| Debt securities issued by foreign governments [Member]
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured
Total invested assets measured on a recurring basis	1,173	1,257
Recurring basis [Member] \| Mortgage-backed securities, collateralized mortgage obligations and pass-through securities [Member]
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured
Total invested assets measured on a recurring basis	3,280	2,573
Recurring basis [Member] \| All other corporate bonds [Member]
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured
Total invested assets measured on a recurring basis	31,619	28,880
Recurring basis [Member] \| Redeemable preferred stock [Member]
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured
Total invested assets measured on a recurring basis	50	79
Recurring basis [Member] \| Equity securities [Member]
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured
Total invested assets measured on a recurring basis	425	368
Recurring basis [Member] \| Public common stock [Member]
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured
Total invested assets measured on a recurring basis	383	316
Recurring basis [Member] \| Non-redeemable preferred stock [Member]
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured
Total invested assets measured on a recurring basis	42	52
Recurring basis [Member] \| Other investments [Member]
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured
Total invested assets measured on a recurring basis	36	52
Recurring basis [Member] \| Level 1 [Member]
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured
Total invested assets measured on a recurring basis	2,507	2,429
Other liabilities measured on a recurring basis	0	0
Recurring basis [Member] \| Level 1 [Member] \| Fixed maturities [Member]
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured
Total invested assets measured on a recurring basis	2,095	2,067
Recurring basis [Member] \| Level 1 [Member] \| U.S. Treasury securities and obligations of U.S. government and government agencies and authorities [Member]
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured
Total invested assets measured on a recurring basis	2,095	2,064
Recurring basis [Member] \| Level 1 [Member] \| Obligations of states, municipalities and political subdivisions [Member]
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured
Total invested assets measured on a recurring basis	0	0
Recurring basis [Member] \| Level 1 [Member] \| Debt securities issued by foreign governments [Member]
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured
Total invested assets measured on a recurring basis	0	0
Recurring basis [Member] \| Level 1 [Member] \| Mortgage-backed securities, collateralized mortgage obligations and pass-through securities [Member]
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured
Total invested assets measured on a recurring basis	0	0
Recurring basis [Member] \| Level 1 [Member] \| All other corporate bonds [Member]
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured
Total invested assets measured on a recurring basis	0	0
Recurring basis [Member] \| Level 1 [Member] \| Redeemable preferred stock [Member]
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured
Total invested assets measured on a recurring basis	0	3
Recurring basis [Member] \| Level 1 [Member] \| Equity securities [Member]
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured
Total invested assets measured on a recurring basis	396	346
Recurring basis [Member] \| Level 1 [Member] \| Public common stock [Member]
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured
Total invested assets measured on a recurring basis	383	316
Recurring basis [Member] \| Level 1 [Member] \| Non-redeemable preferred stock [Member]
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured
Total invested assets measured on a recurring basis	13	30
Recurring basis [Member] \| Level 1 [Member] \| Other investments [Member]
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured
Total invested assets measured on a recurring basis	16	16
Recurring basis [Member] \| Level 1 [Member] \| Investments in various publicly-traded securities, including mutual funds and other small holdings [Member]
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured
Total invested assets measured on a recurring basis	16	16
Recurring basis [Member] \| Level 2 [Member]
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured
Total invested assets measured on a recurring basis	65,967	61,233
Other liabilities measured on a recurring basis	0	0
Recurring basis [Member] \| Level 2 [Member] \| Fixed maturities [Member]
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured
Total invested assets measured on a recurring basis	65,938	61,211
Recurring basis [Member] \| Level 2 [Member] \| U.S. Treasury securities and obligations of U.S. government and government agencies and authorities [Member]
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured
Total invested assets measured on a recurring basis	0	0
Recurring basis [Member] \| Level 2 [Member] \| Obligations of states, municipalities and political subdivisions [Member]
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured
Total invested assets measured on a recurring basis	29,905	28,599
Recurring basis [Member] \| Level 2 [Member] \| Debt securities issued by foreign governments [Member]
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured
Total invested assets measured on a recurring basis	1,173	1,257
Recurring basis [Member] \| Level 2 [Member] \| Mortgage-backed securities, collateralized mortgage obligations and pass-through securities [Member]
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured
Total invested assets measured on a recurring basis	3,280	2,554
Recurring basis [Member] \| Level 2 [Member] \| All other corporate bonds [Member]
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured
Total invested assets measured on a recurring basis	31,530	28,725
Recurring basis [Member] \| Level 2 [Member] \| Redeemable preferred stock [Member]
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured
Total invested assets measured on a recurring basis	50	76
Recurring basis [Member] \| Level 2 [Member] \| Equity securities [Member]
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured
Total invested assets measured on a recurring basis	29	22
Recurring basis [Member] \| Level 2 [Member] \| Public common stock [Member]
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured
Total invested assets measured on a recurring basis	0	0
Recurring basis [Member] \| Level 2 [Member] \| Non-redeemable preferred stock [Member]
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured
Total invested assets measured on a recurring basis	29	22
Recurring basis [Member] \| Level 2 [Member] \| Other investments [Member]
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured
Total invested assets measured on a recurring basis	0	0
Recurring basis [Member] \| Level 3 [Member]
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured
Total invested assets measured on a recurring basis	121	222
Other liabilities measured on a recurring basis	8	10
Estimated fair value of put/call option reported in other liabilities	8	10
Recurring basis [Member] \| Level 3 [Member] \| Fixed maturities [Member]
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured
Total invested assets measured on a recurring basis	101	186
Recurring basis [Member] \| Level 3 [Member] \| U.S. Treasury securities and obligations of U.S. government and government agencies and authorities [Member]
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured
Total invested assets measured on a recurring basis	0	0
Recurring basis [Member] \| Level 3 [Member] \| Obligations of states, municipalities and political subdivisions [Member]
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured
Total invested assets measured on a recurring basis	12	12
Recurring basis [Member] \| Level 3 [Member] \| Debt securities issued by foreign governments [Member]
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured
Total invested assets measured on a recurring basis	0	0
Recurring basis [Member] \| Level 3 [Member] \| Mortgage-backed securities, collateralized mortgage obligations and pass-through securities [Member]
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured
Total invested assets measured on a recurring basis	0	19
Recurring basis [Member] \| Level 3 [Member] \| All other corporate bonds [Member]
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured
Total invested assets measured on a recurring basis	89	155
Recurring basis [Member] \| Level 3 [Member] \| Redeemable preferred stock [Member]
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured
Total invested assets measured on a recurring basis	0	0
Recurring basis [Member] \| Level 3 [Member] \| Equity securities [Member]
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured
Total invested assets measured on a recurring basis	0	0
Recurring basis [Member] \| Level 3 [Member] \| Public common stock [Member]
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured
Total invested assets measured on a recurring basis	0	0
Recurring basis [Member] \| Level 3 [Member] \| Non-redeemable preferred stock [Member]
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured
Total invested assets measured on a recurring basis	0	0
Recurring basis [Member] \| Level 3 [Member] \| Other investments [Member]
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured
Total invested assets measured on a recurring basis	20	36
Recurring basis [Member] \| Level 3 [Member] \| Investment in non-public common and preferred equity securities where the fair value estimate is determined either internally or by an external fund manager [Member]
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured
Total invested assets measured on a recurring basis	$ 20	$ 36

Fair Value Measurements (Deta_3

Fair Value Measurements (Details) - Changes in Level 3 - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Changes in Level 3 fair value category [Roll Forward]
Level 3 fair value category, beginning balance	$ 222	$ 242
Level 3 fair value category, total realized and unrealized investment gains (losses) reported in net realized investment gains	3	9
Level 3 fair value category, total unrealized investment gains (losses) reported in increases in other comprehensive income (loss)	4	(4)
Level 3 fair value category purchases	44	149
Level 3 fair value category sales	(26)	(23)
Level 3 fair value category settlements/maturities	(19)	(71)
Gross transfers into Level 3	0	11
Gross transfers out of Level 3	(107)	(91)
Level 3 fair value category, ending balance	121	222
Amount of total realized investment gains (losses) for the period included in the consolidated statement of income attributable to changes in the fair value of assets still held at the reporting date	0	0
Fixed maturities [Member]
Changes in Level 3 fair value category [Roll Forward]
Level 3 fair value category, beginning balance	186	204
Level 3 fair value category, total realized and unrealized investment gains (losses) reported in net realized investment gains	0	2
Level 3 fair value category, total unrealized investment gains (losses) reported in increases in other comprehensive income (loss)	4	(4)
Level 3 fair value category purchases	38	146
Level 3 fair value category sales	(1)	(11)
Level 3 fair value category settlements/maturities	(19)	(71)
Gross transfers into Level 3	0	11
Gross transfers out of Level 3	(107)	(91)
Level 3 fair value category, ending balance	101	186
Amount of total realized investment gains (losses) for the period included in the consolidated statement of income attributable to changes in the fair value of assets still held at the reporting date	0	0
Other investments [Member]
Changes in Level 3 fair value category [Roll Forward]
Level 3 fair value category, beginning balance	36	38
Level 3 fair value category, total realized and unrealized investment gains (losses) reported in net realized investment gains	3	7
Level 3 fair value category, total unrealized investment gains (losses) reported in increases in other comprehensive income (loss)	0	0
Level 3 fair value category purchases	6	3
Level 3 fair value category sales	(25)	(12)
Level 3 fair value category settlements/maturities	0	0
Gross transfers into Level 3	0	0
Gross transfers out of Level 3	0	0
Level 3 fair value category, ending balance	20	36
Amount of total realized investment gains (losses) for the period included in the consolidated statement of income attributable to changes in the fair value of assets still held at the reporting date	$ 0	$ 0

Fair Value Measurements (Deta_4

Fair Value Measurements (Details) - Financial Instruments - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Financial Instruments
Short-term securities	$ 4,943	$ 3,985
Commercial paper	100	100
Carrying Value [Member]
Financial Instruments
Short-term securities	4,943	3,985
Debt	6,458	6,464
Commercial paper	100	100
Fair Value [Member]
Financial Instruments
Short-term securities	4,943	3,985
Debt	8,049	7,128
Commercial paper	100	100
Fair Value [Member] \| Level 1 [Member]
Financial Instruments
Short-term securities	685	632
Debt	0	0
Commercial paper	0	0
Fair Value [Member] \| Level 2 [Member]
Financial Instruments
Short-term securities	4,204	3,316
Debt	8,049	7,128
Commercial paper	100	100
Fair Value [Member] \| Level 3 [Member]
Financial Instruments
Short-term securities	54	37
Debt	0	0
Commercial paper	$ 0	$ 0

Reinsurance (Details)

Reinsurance (Details) - USD ($) $ in Millions	12 Months Ended
Reinsurance (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Reinsurance Disclosures [Abstract]
Percentage of residual market business written directly by the Company for mandatory pools and associations and then ceded to the mandatory pool	100.00%
Written premiums, direct	$ 30,022	$ 28,210	$ 26,648
Written premiums, assumed	1,041	1,042	1,000
Written premiums, ceded	(1,912)	(1,544)	(1,429)
Total net written premiums	29,151	27,708	26,219
Earned premiums, direct	28,994	27,536	26,189
Earned premiums, assumed	1,076	1,024	965
Earned premiums, ceded	(1,798)	(1,501)	(1,471)
Total net earned premiums	$ 28,272	$ 27,059	$ 25,683
Percentage of assumed earned premiums to net earned premiums	3.80%	3.80%	3.80%
Ceded claims and claim adjustment expenses incurred	$ 1,089	$ 1,293	$ 1,225
Gross reinsurance recoverables on paid and unpaid claims and claim adjustment expenses	3,476	3,485
Allowance for uncollectible reinsurance	(92)	(110)
Net reinsurance recoverables	3,384	3,375
Mandatory pools and associations	1,886	2,005
Structured settlements	2,965	2,990
Total reinsurance recoverables	8,235	$ 8,370
Terrorism Risk Insurance Program, annual aggregate industry loss minimum in order for a loss to be covered	$ 200
Terrorism Risk Insurance Program, percentage of subject losses reimbursed by the Federal Government, after insurer deductible, subject to annual cap	80.00%
Terrorism Risk Insurance Program, percentage of insurer's direct earned premiums for covered lines for the preceding calendar year at which the deductible is set	20.00%
Terrorism Risk Insurance Program, Company's estimated deductible for the next fiscal year	$ 2,610
Terrorism Risk Insurance Program, annual cap limiting amount of aggregate subject losses for all participating insurers	$ 100,000

Goodwill and Other Intangible_3

Goodwill and Other Intangible Assets (Details) - Goodwill - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Goodwill by segment
Goodwill	$ 3,961	$ 3,937
Reportable segments [Member] \| Business Insurance [Member]
Goodwill by segment
Goodwill	2,601	2,585
Reportable segments [Member] \| Bond & Specialty Insurance [Member]
Goodwill by segment
Goodwill	550	550
Reportable segments [Member] \| Personal Insurance [Member]
Goodwill by segment
Goodwill	784	776
Other [Member]
Goodwill by segment
Goodwill	$ 26	$ 26

Goodwill and Other Intangible_4

Goodwill and Other Intangible Assets (Details) - Other Intangible Assets - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Other intangible assets by major asset class
Intangible assets subject to amortization, gross carrying amount	$ 304	$ 306
Intangible assets subject to amortization, accumulated amortization	200	187
Intangible assets subject to amortization, net	104	119
Intangible assets not subject to amortization	226	226
Total other intangible assets, gross carrying amount	530	532
Total other intangible assets, net	330	345
Amortization expense of intangible assets	15	17	$ 13
Estimated intangible asset amortization expense, 2020	15
Estimated intangible asset amortization expense, 2021	14
Estimated intangible asset amortization expense, 2022	13
Estimated intangible asset amortization expense, 2023	12
Estimated intangible asset amortization expense, 2024	12
Customer-related [Member]
Other intangible assets by major asset class
Intangible assets subject to amortization, gross carrying amount	99	98
Intangible assets subject to amortization, accumulated amortization	21	12
Intangible assets subject to amortization, net	78	86
Contract-based [Member]
Other intangible assets by major asset class
Intangible assets subject to amortization, gross carrying amount	205	208
Intangible assets subject to amortization, accumulated amortization	179	175
Intangible assets subject to amortization, net	26	$ 33
Insurance Contracts Acquired in Business Combination [Member]
Other intangible assets by major asset class
Estimated intangible asset amortization expense, 2020	5
Estimated intangible asset amortization expense, 2021	4
Estimated intangible asset amortization expense, 2022	3
Estimated intangible asset amortization expense, 2023	3
Estimated intangible asset amortization expense, 2024	$ 2

Insurance Claim Reserves (Detai

Insurance Claim Reserves (Details) - USD ($) $ in Millions	12 Months Ended
Insurance Claim Reserves (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Reconciliation of beginning and ending reserve balances for claims and claim adjustment expenses [Roll Forward]
Claims and claim adjustment expense reserves at beginning of year	$ 50,668
Net reserves at end of year	43,801
Reinsurance recoverables on unpaid losses	8,048
Claims and claim adjustment expense reserves at end of year	51,849	$ 50,668
Property-casualty [Member]
Reconciliation of beginning and ending reserve balances for claims and claim adjustment expenses [Roll Forward]
Claims and claim adjustment expense reserves at beginning of year	50,653	49,633	$ 47,929
Reinsurance recoverables on unpaid losses	8,182	8,123	7,981
Net reserves at beginning of year	42,471	41,510	39,948
Estimated claims and claim adjustment expenses for claims arising in the current year	18,854	18,614	17,846
Estimated increase (decrease) in claims and claim adjustment expenses for claims arising in prior years	164	(406)	(458)
Total increases	19,018	18,208	17,388
Claims and claim adjustment expense payments for claims arising in current year	7,734	7,697	7,335
Claims and claim adjustment expense payments for claims arising in prior years	10,060	9,363	8,708
Total payments	17,794	17,060	16,043
Unrealized foreign exchange loss (gain)	106	(187)	217
Net reserves at end of year	43,801	42,471	41,510
Reinsurance recoverables on unpaid losses	8,035	8,182	8,123
Claims and claim adjustment expense reserves at end of year	51,836	50,653	49,633
Amount of increase in gross claims and claim adjustment expense reserves	1,180	1,020
Amount of increase (decrease) in reinsurance recoverables on unpaid losses	(147)	$ 59
Reserves for long-term disability and annuity claim payments primarily arising from workers' compensation insurance and workers' compensation excess insurance policies, discount rate (percent)		5.00%
Reserves for long-term disability and annuity claim payments primarily arising from workers' compensation insurance and workers' compensation excess insurance policies, net of discount	2,480	$ 2,450
Discount included in reserves for long-term disability and annuity claim payments primarily arising from workers' compensation insurance and workers' compensation excess insurance policies	1,160	1,160
Accretion expense	49	49	$ 50
Accident and health [Member]
Reconciliation of beginning and ending reserve balances for claims and claim adjustment expenses [Roll Forward]
Claims and claim adjustment expense reserves at beginning of year	15
Net reserves at end of year	0
Reinsurance recoverables on unpaid losses	13
Claims and claim adjustment expense reserves at end of year	$ 13	$ 15
Minimum [Member] \| Property-casualty [Member]
Reconciliation of beginning and ending reserve balances for claims and claim adjustment expenses [Roll Forward]
Reserves for long-term disability and annuity claim payments primarily arising from workers' compensation insurance and workers' compensation excess insurance policies, discount rate (percent)	3.50%
Maximum [Member] \| Property-casualty [Member]
Reconciliation of beginning and ending reserve balances for claims and claim adjustment expenses [Roll Forward]
Reserves for long-term disability and annuity claim payments primarily arising from workers' compensation insurance and workers' compensation excess insurance policies, discount rate (percent)	5.00%

Insurance Claim Reserves (Det_2

Insurance Claim Reserves (Details) - Prior Year Reserve Development - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Asbestos reserves [Member]
Liability for claims and claim adjustment expense
Increase to asbestos and environmental reserves	$ 220	$ 225	$ 225
Environmental reserves [Member]
Liability for claims and claim adjustment expense
Increase to asbestos and environmental reserves	76	55	65
Property-casualty [Member]
Liability for claims and claim adjustment expense
Net favorable (unfavorable) prior year reserve development included in estimated claims and claim adjustment expenses incurred for claims arising in prior years	(164)	406	458
Net favorable (unfavorable) prior year reserve development impacting the Company's results of operations	(60)	517	592
Accretion expense	49	49	50
Property-casualty [Member] \| Business Insurance [Member]
Liability for claims and claim adjustment expense
Net favorable (unfavorable) prior year reserve development impacting the Company's results of operations	(258)	142	439
Property-casualty [Member] \| Business Insurance [Member] \| Asbestos reserves [Member]
Liability for claims and claim adjustment expense
Increase to asbestos and environmental reserves	220	225	225
Property-casualty [Member] \| Business Insurance [Member] \| Environmental reserves [Member]
Liability for claims and claim adjustment expense
Increase to asbestos and environmental reserves	76	55	65
Property-casualty [Member] \| Bond & Specialty Insurance [Member]
Liability for claims and claim adjustment expense
Net favorable (unfavorable) prior year reserve development impacting the Company's results of operations	65	266	140
Property-casualty [Member] \| Personal Insurance [Member]
Liability for claims and claim adjustment expense
Net favorable (unfavorable) prior year reserve development impacting the Company's results of operations	$ 133	$ 109	$ 13

Insurance Claim Reserves (Det_3

Insurance Claim Reserves (Details) - Claims and Claim Adjustment Expenses Reserves Summary - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability
Net Undiscounted Claims and Claim Adjustment Expense Reserves	$ 44,889
Discount (Net of Reinsurance)	(1,088)
Subtotal: Net Claims and Claim Adjustment Expense Reserves	43,801
Reinsurance Recoverables on Unpaid Losses	8,048
Claims and Claim Adjustment Expense Reserves	51,849	$ 50,668
Discount on reinsurance recoverables for long-term disability and annuity claim payments included in discount (net of reinsurance)	67
Total reinsurance recoverables	8,235	8,370
Property-casualty [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability
Net Undiscounted Claims and Claim Adjustment Expense Reserves	44,889
Discount (Net of Reinsurance)	(1,088)
Subtotal: Net Claims and Claim Adjustment Expense Reserves	43,801	42,471	$ 41,510	$ 39,948
Reinsurance Recoverables on Unpaid Losses	8,035	8,182	8,123	7,981
Claims and Claim Adjustment Expense Reserves	51,836	50,653	$ 49,633	$ 47,929
Accident and health [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability
Net Undiscounted Claims and Claim Adjustment Expense Reserves	0
Discount (Net of Reinsurance)	0
Subtotal: Net Claims and Claim Adjustment Expense Reserves	0
Reinsurance Recoverables on Unpaid Losses	13
Claims and Claim Adjustment Expense Reserves	13	$ 15
Business Insurance [Member] \| General liability [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability
Net Undiscounted Claims and Claim Adjustment Expense Reserves	7,749
Business Insurance [Member] \| Commercial property [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability
Net Undiscounted Claims and Claim Adjustment Expense Reserves	887
Business Insurance [Member] \| Commercial multi-peril [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability
Net Undiscounted Claims and Claim Adjustment Expense Reserves	3,784
Business Insurance [Member] \| Automobile [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability
Net Undiscounted Claims and Claim Adjustment Expense Reserves	3,237
Business Insurance [Member] \| Workers' compensation [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability
Net Undiscounted Claims and Claim Adjustment Expense Reserves	16,184
Bond & Specialty Insurance [Member] \| General liability [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability
Net Undiscounted Claims and Claim Adjustment Expense Reserves	1,824
Bond & Specialty Insurance [Member] \| Fidelity and surety [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability
Net Undiscounted Claims and Claim Adjustment Expense Reserves	399
Personal Insurance [Member] \| Automobile [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability
Net Undiscounted Claims and Claim Adjustment Expense Reserves	2,862
Personal Insurance [Member] \| Homeowners (excluding Other) [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability
Net Undiscounted Claims and Claim Adjustment Expense Reserves	1,168
Personal Insurance [Member] \| International - Canada [Member] \| Property-casualty [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability
Net Undiscounted Claims and Claim Adjustment Expense Reserves	739
Reportable segments [Member] \| Property-casualty [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability
Net Undiscounted Claims and Claim Adjustment Expense Reserves	38,833
Discount (Net of Reinsurance)	(1,083)
Subtotal: Net Claims and Claim Adjustment Expense Reserves	37,750
Reinsurance Recoverables on Unpaid Losses	3,084
Claims and Claim Adjustment Expense Reserves	40,834
Reportable segments [Member] \| Business Insurance [Member] \| General liability [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability
Net Undiscounted Claims and Claim Adjustment Expense Reserves	7,749
Discount (Net of Reinsurance)	(172)
Subtotal: Net Claims and Claim Adjustment Expense Reserves	7,577
Reinsurance Recoverables on Unpaid Losses	842
Claims and Claim Adjustment Expense Reserves	8,419
Reportable segments [Member] \| Business Insurance [Member] \| Commercial property [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability
Net Undiscounted Claims and Claim Adjustment Expense Reserves	887
Discount (Net of Reinsurance)	0
Subtotal: Net Claims and Claim Adjustment Expense Reserves	887
Reinsurance Recoverables on Unpaid Losses	389
Claims and Claim Adjustment Expense Reserves	1,276
Reportable segments [Member] \| Business Insurance [Member] \| Commercial multi-peril [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability
Net Undiscounted Claims and Claim Adjustment Expense Reserves	3,784
Discount (Net of Reinsurance)	0
Subtotal: Net Claims and Claim Adjustment Expense Reserves	3,784
Reinsurance Recoverables on Unpaid Losses	175
Claims and Claim Adjustment Expense Reserves	3,959
Reportable segments [Member] \| Business Insurance [Member] \| Automobile [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability
Net Undiscounted Claims and Claim Adjustment Expense Reserves	3,237
Discount (Net of Reinsurance)	0
Subtotal: Net Claims and Claim Adjustment Expense Reserves	3,237
Reinsurance Recoverables on Unpaid Losses	259
Claims and Claim Adjustment Expense Reserves	3,496
Reportable segments [Member] \| Business Insurance [Member] \| Workers' compensation [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability
Net Undiscounted Claims and Claim Adjustment Expense Reserves	16,184
Discount (Net of Reinsurance)	(911)
Subtotal: Net Claims and Claim Adjustment Expense Reserves	15,273
Reinsurance Recoverables on Unpaid Losses	745
Claims and Claim Adjustment Expense Reserves	16,018
Reportable segments [Member] \| Bond & Specialty Insurance [Member] \| General liability [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability
Net Undiscounted Claims and Claim Adjustment Expense Reserves	1,824
Discount (Net of Reinsurance)	0
Subtotal: Net Claims and Claim Adjustment Expense Reserves	1,824
Reinsurance Recoverables on Unpaid Losses	108
Claims and Claim Adjustment Expense Reserves	1,932
Reportable segments [Member] \| Bond & Specialty Insurance [Member] \| Fidelity and surety [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability
Net Undiscounted Claims and Claim Adjustment Expense Reserves	399
Discount (Net of Reinsurance)	0
Subtotal: Net Claims and Claim Adjustment Expense Reserves	399
Reinsurance Recoverables on Unpaid Losses	4
Claims and Claim Adjustment Expense Reserves	403
Reportable segments [Member] \| Personal Insurance [Member] \| Automobile [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability
Net Undiscounted Claims and Claim Adjustment Expense Reserves	2,862
Discount (Net of Reinsurance)	0
Subtotal: Net Claims and Claim Adjustment Expense Reserves	2,862
Reinsurance Recoverables on Unpaid Losses	486
Claims and Claim Adjustment Expense Reserves	3,348
Reportable segments [Member] \| Personal Insurance [Member] \| Homeowners (excluding Other) [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability
Net Undiscounted Claims and Claim Adjustment Expense Reserves	1,168
Discount (Net of Reinsurance)	0
Subtotal: Net Claims and Claim Adjustment Expense Reserves	1,168
Reinsurance Recoverables on Unpaid Losses	57
Claims and Claim Adjustment Expense Reserves	1,225
Reportable segments [Member] \| Personal Insurance [Member] \| International - Canada [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability
Net Undiscounted Claims and Claim Adjustment Expense Reserves	739
Discount (Net of Reinsurance)	0
Subtotal: Net Claims and Claim Adjustment Expense Reserves	739
Reinsurance Recoverables on Unpaid Losses	19
Claims and Claim Adjustment Expense Reserves	758
Reconciling Items [Member] \| Other insurance contracts [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability
Net Undiscounted Claims and Claim Adjustment Expense Reserves	3,895
Discount (Net of Reinsurance)	(5)
Subtotal: Net Claims and Claim Adjustment Expense Reserves	3,890
Reinsurance Recoverables on Unpaid Losses	1,968
Claims and Claim Adjustment Expense Reserves	5,858
Reconciling Items [Member] \| Unallocated loss adjustment expense reserves [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability
Net Undiscounted Claims and Claim Adjustment Expense Reserves	2,104
Discount (Net of Reinsurance)	0
Subtotal: Net Claims and Claim Adjustment Expense Reserves	2,104
Reinsurance Recoverables on Unpaid Losses	39
Claims and Claim Adjustment Expense Reserves	2,143
Reconciling Items [Member] \| Structured settlements [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability
Net Undiscounted Claims and Claim Adjustment Expense Reserves	0
Discount (Net of Reinsurance)	0
Subtotal: Net Claims and Claim Adjustment Expense Reserves	0
Reinsurance Recoverables on Unpaid Losses	2,965
Claims and Claim Adjustment Expense Reserves	2,965
Reconciling Items [Member] \| Other [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability
Net Undiscounted Claims and Claim Adjustment Expense Reserves	57
Discount (Net of Reinsurance)	0
Subtotal: Net Claims and Claim Adjustment Expense Reserves	57
Reinsurance Recoverables on Unpaid Losses	(21)
Claims and Claim Adjustment Expense Reserves	$ 36

Insurance Claim Reserves (Det_4

Insurance Claim Reserves (Details) - Claim Development $ in Millions	Dec. 31, 2019USD ($)item	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)	Dec. 31, 2012USD ($)	Dec. 31, 2011USD ($)	Dec. 31, 2010USD ($)
Claims Development
Total net liability (Audited)	$ 44,889
Property-casualty [Member]
Claims Development
Total net liability (Audited)	44,889
Business Insurance [Member] \| General liability [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	10,929
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	6,030
Liability for Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance, Disclosed Accident Years (Audited)	4,899
Liability for Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance, Before Disclosed Accident Years (Audited)	2,850
Total net liability (Audited)	7,749
Business Insurance [Member] \| Commercial property [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	4,845
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	4,095
Liability for Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance, Disclosed Accident Years (Audited)	750
Liability for Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance, Before Disclosed Accident Years (Audited)	137
Total net liability (Audited)	887
Business Insurance [Member] \| Commercial multi-peril [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	18,503
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	14,990
Liability for Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance, Disclosed Accident Years (Audited)	3,513
Liability for Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance, Before Disclosed Accident Years (Audited)	271
Total net liability (Audited)	3,784
Business Insurance [Member] \| Automobile [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	7,808
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	4,753
Liability for Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance, Disclosed Accident Years (Audited)	3,055
Liability for Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance, Before Disclosed Accident Years (Audited)	182
Total net liability (Audited)	3,237
Business Insurance [Member] \| Workers' compensation [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	24,234
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	13,419
Liability for Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance, Disclosed Accident Years (Audited)	10,815
Liability for Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance, Before Disclosed Accident Years (Audited)	5,369
Total net liability (Audited)	16,184
Bond & Specialty Insurance [Member] \| General liability [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	5,374
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	3,588
Liability for Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance, Disclosed Accident Years (Audited)	1,786
Liability for Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance, Before Disclosed Accident Years (Audited)	38
Total net liability (Audited)	1,824
Bond & Specialty Insurance [Member] \| Fidelity and surety [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	1,023
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	651
Liability for Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance, Disclosed Accident Years (Audited)	372
Liability for Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance, Before Disclosed Accident Years (Audited)	27
Total net liability (Audited)	399
Personal Insurance [Member] \| Automobile [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	14,823
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	12,192
Liability for Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance, Disclosed Accident Years (Audited)	2,631
Liability for Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance, Before Disclosed Accident Years (Audited)	231
Total net liability (Audited)	2,862
Personal Insurance [Member] \| Homeowners (excluding Other) [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	10,168
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	9,016
Liability for Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance, Disclosed Accident Years (Audited)	1,152
Liability for Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance, Before Disclosed Accident Years (Audited)	16
Total net liability (Audited)	1,168
Personal Insurance [Member] \| International - Canada [Member] \| Property-casualty [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	4,190
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	3,472
Liability for Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance, Disclosed Accident Years (Audited)	718
Liability for Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance, Before Disclosed Accident Years (Audited)	21
Total net liability (Audited)	739
Short-duration Insurance Contracts, Accident Year 2010 [Member] \| Business Insurance [Member] \| General liability [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	900	$ 911	$ 908	$ 918	$ 912	$ 927	$ 959	$ 1,021	$ 1,031	$ 1,028
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	814	800	781	756	702	629	487	324	139	35
IBNR Reserves Dec. 31, 2019 (Audited)	$ 62
Cumulative Number of Reported Claims (Audited) \| item	27,993
Short-duration Insurance Contracts, Accident Year 2010 [Member] \| Business Insurance [Member] \| Commercial multi-peril [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	$ 1,868	1,881	1,885	1,898	1,892	1,895	1,861	1,832	1,826	1,711
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	1,840	1,834	1,819	1,798	1,763	1,698	1,579	1,395	1,180	709
IBNR Reserves Dec. 31, 2019 (Audited)	$ 19
Cumulative Number of Reported Claims (Audited) \| item	112,074
Short-duration Insurance Contracts, Accident Year 2010 [Member] \| Business Insurance [Member] \| Workers' compensation [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	$ 1,984	2,003	2,021	2,055	2,052	2,049	2,056	2,035	2,042	1,886
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	1,490	1,465	1,430	1,385	1,321	1,246	1,133	978	750	341
IBNR Reserves Dec. 31, 2019 (Audited)	$ 248
Cumulative Number of Reported Claims (Audited) \| item	117,466
Short-duration Insurance Contracts, Accident Year 2010 [Member] \| Bond & Specialty Insurance [Member] \| General liability [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	$ 660	657	653	653	668	661	679	679	612	571
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	635	631	623	597	565	482	396	291	152	33
IBNR Reserves Dec. 31, 2019 (Audited)	$ 16
Cumulative Number of Reported Claims (Audited) \| item	5,677
Short-duration Insurance Contracts, Accident Year 2010 [Member] \| Personal Insurance [Member] \| International - Canada [Member] \| Property-casualty [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	$ 477	481	482	489	493	501	514	499	488	487
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	468	465	459	447	430	400	369	329	292	$ 191
IBNR Reserves Dec. 31, 2019 (Audited)	$ 1
Cumulative Number of Reported Claims (Audited) \| item	54,938
Short-duration Insurance Contracts, Accident Year 2011 [Member] \| Business Insurance [Member] \| General liability [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	$ 922	908	913	935	972	998	1,065	1,074	1,004
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	819	799	762	725	660	539	355	187	47
IBNR Reserves Dec. 31, 2019 (Audited)	$ 69
Cumulative Number of Reported Claims (Audited) \| item	27,557
Short-duration Insurance Contracts, Accident Year 2011 [Member] \| Business Insurance [Member] \| Commercial multi-peril [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	$ 2,272	2,279	2,283	2,287	2,296	2,286	2,269	2,244	2,235
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	2,234	2,222	2,193	2,156	2,088	1,979	1,803	1,573	1,060
IBNR Reserves Dec. 31, 2019 (Audited)	$ 25
Cumulative Number of Reported Claims (Audited) \| item	125,867
Short-duration Insurance Contracts, Accident Year 2011 [Member] \| Business Insurance [Member] \| Workers' compensation [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	$ 2,320	2,348	2,363	2,385	2,379	2,350	2,347	2,303	2,284
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	1,732	1,696	1,652	1,583	1,487	1,365	1,185	911	420
IBNR Reserves Dec. 31, 2019 (Audited)	$ 319
Cumulative Number of Reported Claims (Audited) \| item	136,801
Short-duration Insurance Contracts, Accident Year 2011 [Member] \| Bond & Specialty Insurance [Member] \| General liability [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	$ 506	508	520	545	601	632	639	596	565
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	496	490	476	447	414	324	249	143	33
IBNR Reserves Dec. 31, 2019 (Audited)	$ 2
Cumulative Number of Reported Claims (Audited) \| item	5,213
Short-duration Insurance Contracts, Accident Year 2011 [Member] \| Personal Insurance [Member] \| International - Canada [Member] \| Property-casualty [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	$ 408	417	422	427	434	441	446	438	459
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	401	397	389	371	349	314	280	249	$ 176
IBNR Reserves Dec. 31, 2019 (Audited)	$ (5)
Cumulative Number of Reported Claims (Audited) \| item	55,773
Short-duration Insurance Contracts, Accident Year 2012 [Member] \| Business Insurance [Member] \| General liability [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	$ 920	917	905	892	913	935	985	989
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	811	754	699	589	489	295	150	32
IBNR Reserves Dec. 31, 2019 (Audited)	$ 78
Cumulative Number of Reported Claims (Audited) \| item	24,920
Short-duration Insurance Contracts, Accident Year 2012 [Member] \| Business Insurance [Member] \| Commercial multi-peril [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	$ 1,854	1,859	1,867	1,888	1,888	1,903	1,883	1,885
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	1,804	1,780	1,752	1,699	1,590	1,424	1,246	795
IBNR Reserves Dec. 31, 2019 (Audited)	$ 34
Cumulative Number of Reported Claims (Audited) \| item	104,921
Short-duration Insurance Contracts, Accident Year 2012 [Member] \| Business Insurance [Member] \| Workers' compensation [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	$ 2,387	2,416	2,453	2,445	2,456	2,457	2,456	2,447
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	1,735	1,689	1,629	1,536	1,394	1,217	940	443
IBNR Reserves Dec. 31, 2019 (Audited)	$ 367
Cumulative Number of Reported Claims (Audited) \| item	138,034
Short-duration Insurance Contracts, Accident Year 2012 [Member] \| Bond & Specialty Insurance [Member] \| General liability [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	$ 593	605	599	601	605	614	591	538
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	453	436	419	383	342	255	160	38
IBNR Reserves Dec. 31, 2019 (Audited)	$ 60
Cumulative Number of Reported Claims (Audited) \| item	4,865
Short-duration Insurance Contracts, Accident Year 2012 [Member] \| Personal Insurance [Member] \| International - Canada [Member] \| Property-casualty [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	$ 362	374	380	397	398	414	413	435
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	347	342	333	316	288	262	231	$ 165
IBNR Reserves Dec. 31, 2019 (Audited)	$ (2)
Cumulative Number of Reported Claims (Audited) \| item	51,208
Short-duration Insurance Contracts, Accident Year 2013 [Member] \| Business Insurance [Member] \| General liability [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	$ 975	933	927	940	958	975	965
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	816	745	639	498	363	175	35
IBNR Reserves Dec. 31, 2019 (Audited)	$ 104
Cumulative Number of Reported Claims (Audited) \| item	22,625
Short-duration Insurance Contracts, Accident Year 2013 [Member] \| Business Insurance [Member] \| Commercial multi-peril [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	$ 1,599	1,600	1,591	1,609	1,620	1,623	1,615
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	1,516	1,475	1,410	1,304	1,167	987	644
IBNR Reserves Dec. 31, 2019 (Audited)	$ 38
Cumulative Number of Reported Claims (Audited) \| item	83,818
Short-duration Insurance Contracts, Accident Year 2013 [Member] \| Business Insurance [Member] \| Workers' compensation [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	$ 2,354	2,423	2,463	2,506	2,540	2,545	2,553
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	1,659	1,604	1,525	1,413	1,237	954	458
IBNR Reserves Dec. 31, 2019 (Audited)	$ 408
Cumulative Number of Reported Claims (Audited) \| item	134,091
Short-duration Insurance Contracts, Accident Year 2013 [Member] \| Bond & Specialty Insurance [Member] \| General liability [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	$ 586	607	654	630	606	565	510
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	451	434	400	352	252	154	34
IBNR Reserves Dec. 31, 2019 (Audited)	$ 42
Cumulative Number of Reported Claims (Audited) \| item	4,456
Short-duration Insurance Contracts, Accident Year 2013 [Member] \| Personal Insurance [Member] \| International - Canada [Member] \| Property-casualty [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	$ 433	443	444	457	469	478	485
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	405	387	369	336	304	272	$ 194
IBNR Reserves Dec. 31, 2019 (Audited)	$ 0
Cumulative Number of Reported Claims (Audited) \| item	54,251
Short-duration Insurance Contracts, Accident Year 2014 [Member] \| Business Insurance [Member] \| General liability [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	$ 1,013	956	948	983	989	976
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	750	640	515	321	163	37
IBNR Reserves Dec. 31, 2019 (Audited)	$ 159
Cumulative Number of Reported Claims (Audited) \| item	22,319
Short-duration Insurance Contracts, Accident Year 2014 [Member] \| Business Insurance [Member] \| Commercial multi-peril [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	$ 1,627	1,626	1,617	1,625	1,627	1,663
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	1,512	1,448	1,328	1,154	956	628
IBNR Reserves Dec. 31, 2019 (Audited)	$ 50
Cumulative Number of Reported Claims (Audited) \| item	78,292
Short-duration Insurance Contracts, Accident Year 2014 [Member] \| Business Insurance [Member] \| Workers' compensation [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	$ 2,393	2,430	2,476	2,547	2,553	2,554
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	1,581	1,505	1,399	1,224	944	455
IBNR Reserves Dec. 31, 2019 (Audited)	$ 486
Cumulative Number of Reported Claims (Audited) \| item	129,293
Short-duration Insurance Contracts, Accident Year 2014 [Member] \| Bond & Specialty Insurance [Member] \| General liability [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	$ 452	473	518	563	571	549
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	407	367	312	239	150	38
IBNR Reserves Dec. 31, 2019 (Audited)	$ 32
Cumulative Number of Reported Claims (Audited) \| item	4,356
Short-duration Insurance Contracts, Accident Year 2014 [Member] \| Personal Insurance [Member] \| International - Canada [Member] \| Property-casualty [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	$ 423	426	433	445	444	429
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	384	362	331	302	265	$ 189
IBNR Reserves Dec. 31, 2019 (Audited)	$ (9)
Cumulative Number of Reported Claims (Audited) \| item	52,268
Short-duration Insurance Contracts, Accident Year 2015 [Member] \| Business Insurance [Member] \| General liability [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	$ 1,057	967	923	956	998
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	740	558	336	137	36
IBNR Reserves Dec. 31, 2019 (Audited)	$ 165
Cumulative Number of Reported Claims (Audited) \| item	21,360
Short-duration Insurance Contracts, Accident Year 2015 [Member] \| Business Insurance [Member] \| Commercial property [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	$ 737	731	741	750	786
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	717	699	681	615	376
IBNR Reserves Dec. 31, 2019 (Audited)	$ 8
Cumulative Number of Reported Claims (Audited) \| item	20,162
Short-duration Insurance Contracts, Accident Year 2015 [Member] \| Business Insurance [Member] \| Commercial multi-peril [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	$ 1,606	1,597	1,593	1,625	1,568
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	1,409	1,310	1,144	970	595
IBNR Reserves Dec. 31, 2019 (Audited)	$ 92
Cumulative Number of Reported Claims (Audited) \| item	71,635
Short-duration Insurance Contracts, Accident Year 2015 [Member] \| Business Insurance [Member] \| Automobile [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	$ 1,298	1,283	1,234	1,202	1,188
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	1,181	1,058	885	650	405
IBNR Reserves Dec. 31, 2019 (Audited)	$ 48
Cumulative Number of Reported Claims (Audited) \| item	173,545
Short-duration Insurance Contracts, Accident Year 2015 [Member] \| Business Insurance [Member] \| Workers' compensation [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	$ 2,372	2,441	2,505	2,585	2,644
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	1,411	1,310	1,154	893	430
IBNR Reserves Dec. 31, 2019 (Audited)	$ 636
Cumulative Number of Reported Claims (Audited) \| item	123,163
Short-duration Insurance Contracts, Accident Year 2015 [Member] \| Bond & Specialty Insurance [Member] \| General liability [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	$ 395	437	486	524	528
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	338	310	234	141	38
IBNR Reserves Dec. 31, 2019 (Audited)	$ 38
Cumulative Number of Reported Claims (Audited) \| item	4,195
Short-duration Insurance Contracts, Accident Year 2015 [Member] \| Bond & Specialty Insurance [Member] \| Fidelity and surety [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	$ 137	145	179	191	217
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	88	86	87	75	32
IBNR Reserves Dec. 31, 2019 (Audited)	$ 32
Cumulative Number of Reported Claims (Audited) \| item	834
Short-duration Insurance Contracts, Accident Year 2015 [Member] \| Personal Insurance [Member] \| Automobile [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	$ 2,219	2,222	2,236	2,244	2,186
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	2,174	2,109	1,985	1,768	1,319
IBNR Reserves Dec. 31, 2019 (Audited)	$ 11
Cumulative Number of Reported Claims (Audited) \| item	757,972
Short-duration Insurance Contracts, Accident Year 2015 [Member] \| Personal Insurance [Member] \| Homeowners (excluding Other) [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	$ 1,443	1,452	1,461	1,454	1,438
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	1,429	1,421	1,395	1,333	994
IBNR Reserves Dec. 31, 2019 (Audited)	$ 1
Cumulative Number of Reported Claims (Audited) \| item	145,136
Short-duration Insurance Contracts, Accident Year 2015 [Member] \| Personal Insurance [Member] \| International - Canada [Member] \| Property-casualty [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	$ 358	356	360	360	361
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	307	282	253	226	$ 162
IBNR Reserves Dec. 31, 2019 (Audited)	$ 10
Cumulative Number of Reported Claims (Audited) \| item	45,203
Short-duration Insurance Contracts, Accident Year 2016 [Member] \| Business Insurance [Member] \| General liability [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	$ 1,187	1,087	1,058	1,075
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	649	421	191	35
IBNR Reserves Dec. 31, 2019 (Audited)	$ 359
Cumulative Number of Reported Claims (Audited) \| item	19,997
Short-duration Insurance Contracts, Accident Year 2016 [Member] \| Business Insurance [Member] \| Commercial property [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	$ 809	820	863	896
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	767	745	685	441
IBNR Reserves Dec. 31, 2019 (Audited)	$ 11
Cumulative Number of Reported Claims (Audited) \| item	22,313
Short-duration Insurance Contracts, Accident Year 2016 [Member] \| Business Insurance [Member] \| Commercial multi-peril [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	$ 1,590	1,598	1,623	1,662
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	1,278	1,133	950	585
IBNR Reserves Dec. 31, 2019 (Audited)	$ 122
Cumulative Number of Reported Claims (Audited) \| item	68,888
Short-duration Insurance Contracts, Accident Year 2016 [Member] \| Business Insurance [Member] \| Automobile [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	$ 1,409	1,371	1,303	1,278
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	1,158	931	688	412
IBNR Reserves Dec. 31, 2019 (Audited)	$ 94
Cumulative Number of Reported Claims (Audited) \| item	183,114
Short-duration Insurance Contracts, Accident Year 2016 [Member] \| Business Insurance [Member] \| Workers' compensation [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	$ 2,473	2,569	2,690	2,768
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	1,272	1,118	873	421
IBNR Reserves Dec. 31, 2019 (Audited)	$ 702
Cumulative Number of Reported Claims (Audited) \| item	122,944
Short-duration Insurance Contracts, Accident Year 2016 [Member] \| Bond & Specialty Insurance [Member] \| General liability [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	$ 520	504	511	512
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	313	233	141	30
IBNR Reserves Dec. 31, 2019 (Audited)	$ 91
Cumulative Number of Reported Claims (Audited) \| item	4,326
Short-duration Insurance Contracts, Accident Year 2016 [Member] \| Bond & Specialty Insurance [Member] \| Fidelity and surety [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	$ 208	205	239	226
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	149	142	121	54
IBNR Reserves Dec. 31, 2019 (Audited)	$ 9
Cumulative Number of Reported Claims (Audited) \| item	886
Short-duration Insurance Contracts, Accident Year 2016 [Member] \| Personal Insurance [Member] \| Automobile [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	$ 2,752	2,772	2,791	2,779
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	2,616	2,466	2,203	1,610
IBNR Reserves Dec. 31, 2019 (Audited)	$ 44
Cumulative Number of Reported Claims (Audited) \| item	922,014
Short-duration Insurance Contracts, Accident Year 2016 [Member] \| Personal Insurance [Member] \| Homeowners (excluding Other) [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	$ 1,511	1,525	1,547	1,556
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	1,479	1,455	1,392	1,049
IBNR Reserves Dec. 31, 2019 (Audited)	$ 8
Cumulative Number of Reported Claims (Audited) \| item	143,949
Short-duration Insurance Contracts, Accident Year 2016 [Member] \| Personal Insurance [Member] \| International - Canada [Member] \| Property-casualty [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	$ 419	409	409	361
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	343	310	283	$ 211
IBNR Reserves Dec. 31, 2019 (Audited)	$ 19
Cumulative Number of Reported Claims (Audited) \| item	45,759
Short-duration Insurance Contracts, Accident Year 2017 [Member] \| Business Insurance [Member] \| General liability [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	$ 1,196	1,143	1,133
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	378	180	40
IBNR Reserves Dec. 31, 2019 (Audited)	$ 530
Cumulative Number of Reported Claims (Audited) \| item	18,014
Short-duration Insurance Contracts, Accident Year 2017 [Member] \| Business Insurance [Member] \| Commercial property [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	$ 1,151	1,177	1,209
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	1,073	1,003	618
IBNR Reserves Dec. 31, 2019 (Audited)	$ 11
Cumulative Number of Reported Claims (Audited) \| item	25,066
Short-duration Insurance Contracts, Accident Year 2017 [Member] \| Business Insurance [Member] \| Commercial multi-peril [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	$ 1,956	1,928	1,872
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	1,388	1,199	716
IBNR Reserves Dec. 31, 2019 (Audited)	$ 266
Cumulative Number of Reported Claims (Audited) \| item	71,220
Short-duration Insurance Contracts, Accident Year 2017 [Member] \| Business Insurance [Member] \| Automobile [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	$ 1,524	1,501	1,386
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	1,027	746	456
IBNR Reserves Dec. 31, 2019 (Audited)	$ 219
Cumulative Number of Reported Claims (Audited) \| item	191,166
Short-duration Insurance Contracts, Accident Year 2017 [Member] \| Business Insurance [Member] \| Workers' compensation [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	$ 2,584	2,681	2,779
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	1,154	890	433
IBNR Reserves Dec. 31, 2019 (Audited)	$ 918
Cumulative Number of Reported Claims (Audited) \| item	120,900
Short-duration Insurance Contracts, Accident Year 2017 [Member] \| Bond & Specialty Insurance [Member] \| General liability [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	$ 526	517	534
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	262	155	38
IBNR Reserves Dec. 31, 2019 (Audited)	$ 174
Cumulative Number of Reported Claims (Audited) \| item	4,455
Short-duration Insurance Contracts, Accident Year 2017 [Member] \| Bond & Specialty Insurance [Member] \| Fidelity and surety [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	$ 240	271	244
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	194	166	70
IBNR Reserves Dec. 31, 2019 (Audited)	$ 22
Cumulative Number of Reported Claims (Audited) \| item	905
Short-duration Insurance Contracts, Accident Year 2017 [Member] \| Personal Insurance [Member] \| Automobile [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	$ 3,221	3,256	3,323
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	2,887	2,575	1,912
IBNR Reserves Dec. 31, 2019 (Audited)	$ 139
Cumulative Number of Reported Claims (Audited) \| item	1,061,907
Short-duration Insurance Contracts, Accident Year 2017 [Member] \| Personal Insurance [Member] \| Homeowners (excluding Other) [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	$ 2,343	2,340	2,312
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	2,197	2,059	1,471
IBNR Reserves Dec. 31, 2019 (Audited)	$ 49
Cumulative Number of Reported Claims (Audited) \| item	169,085
Short-duration Insurance Contracts, Accident Year 2017 [Member] \| Personal Insurance [Member] \| International - Canada [Member] \| Property-casualty [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	$ 403	381	346
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	296	257	$ 182
IBNR Reserves Dec. 31, 2019 (Audited)	$ 34
Cumulative Number of Reported Claims (Audited) \| item	46,769
Short-duration Insurance Contracts, Accident Year 2018 [Member] \| Business Insurance [Member] \| General liability [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	$ 1,312	1,253
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	202	42
IBNR Reserves Dec. 31, 2019 (Audited)	$ 841
Cumulative Number of Reported Claims (Audited) \| item	16,694
Short-duration Insurance Contracts, Accident Year 2018 [Member] \| Business Insurance [Member] \| Commercial property [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	$ 1,079	1,093
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	928	561
IBNR Reserves Dec. 31, 2019 (Audited)	$ 10
Cumulative Number of Reported Claims (Audited) \| item	24,785
Short-duration Insurance Contracts, Accident Year 2018 [Member] \| Business Insurance [Member] \| Commercial multi-peril [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	$ 2,114	1,976
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	1,302	792
IBNR Reserves Dec. 31, 2019 (Audited)	$ 416
Cumulative Number of Reported Claims (Audited) \| item	68,403
Short-duration Insurance Contracts, Accident Year 2018 [Member] \| Business Insurance [Member] \| Automobile [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	$ 1,742	1,645
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	848	515
IBNR Reserves Dec. 31, 2019 (Audited)	$ 469
Cumulative Number of Reported Claims (Audited) \| item	201,578
Short-duration Insurance Contracts, Accident Year 2018 [Member] \| Business Insurance [Member] \| Workers' compensation [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	$ 2,687	2,744
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	919	440
IBNR Reserves Dec. 31, 2019 (Audited)	$ 1,180
Cumulative Number of Reported Claims (Audited) \| item	121,460
Short-duration Insurance Contracts, Accident Year 2018 [Member] \| Bond & Specialty Insurance [Member] \| General liability [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	$ 548	530
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	182	49
IBNR Reserves Dec. 31, 2019 (Audited)	$ 243
Cumulative Number of Reported Claims (Audited) \| item	4,393
Short-duration Insurance Contracts, Accident Year 2018 [Member] \| Bond & Specialty Insurance [Member] \| Fidelity and surety [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	$ 235	220
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	171	64
IBNR Reserves Dec. 31, 2019 (Audited)	$ 22
Cumulative Number of Reported Claims (Audited) \| item	849
Short-duration Insurance Contracts, Accident Year 2018 [Member] \| Personal Insurance [Member] \| Automobile [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	$ 3,269	3,281
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	2,582	1,889
IBNR Reserves Dec. 31, 2019 (Audited)	$ 347
Cumulative Number of Reported Claims (Audited) \| item	1,048,084
Short-duration Insurance Contracts, Accident Year 2018 [Member] \| Personal Insurance [Member] \| Homeowners (excluding Other) [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	$ 2,574	2,610
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	2,298	1,657
IBNR Reserves Dec. 31, 2019 (Audited)	$ 112
Cumulative Number of Reported Claims (Audited) \| item	185,384
Short-duration Insurance Contracts, Accident Year 2018 [Member] \| Personal Insurance [Member] \| International - Canada [Member] \| Property-casualty [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	$ 462	440
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	305	$ 219
IBNR Reserves Dec. 31, 2019 (Audited)	$ 64
Cumulative Number of Reported Claims (Audited) \| item	50,302
Short-duration Insurance Contracts, Accident Year 2019 [Member] \| Business Insurance [Member] \| General liability [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	$ 1,447
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	51
IBNR Reserves Dec. 31, 2019 (Audited)	$ 1,231
Cumulative Number of Reported Claims (Audited) \| item	12,167
Short-duration Insurance Contracts, Accident Year 2019 [Member] \| Business Insurance [Member] \| Commercial property [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	$ 1,069
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	610
IBNR Reserves Dec. 31, 2019 (Audited)	$ 84
Cumulative Number of Reported Claims (Audited) \| item	22,186
Short-duration Insurance Contracts, Accident Year 2019 [Member] \| Business Insurance [Member] \| Commercial multi-peril [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	$ 2,017
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	707
IBNR Reserves Dec. 31, 2019 (Audited)	$ 715
Cumulative Number of Reported Claims (Audited) \| item	70,798
Short-duration Insurance Contracts, Accident Year 2019 [Member] \| Business Insurance [Member] \| Automobile [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	$ 1,835
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	539
IBNR Reserves Dec. 31, 2019 (Audited)	$ 838
Cumulative Number of Reported Claims (Audited) \| item	167,863
Short-duration Insurance Contracts, Accident Year 2019 [Member] \| Business Insurance [Member] \| Workers' compensation [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	$ 2,680
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	466
IBNR Reserves Dec. 31, 2019 (Audited)	$ 1,619
Cumulative Number of Reported Claims (Audited) \| item	107,298
Short-duration Insurance Contracts, Accident Year 2019 [Member] \| Bond & Specialty Insurance [Member] \| General liability [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	$ 588
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	51
IBNR Reserves Dec. 31, 2019 (Audited)	$ 432
Cumulative Number of Reported Claims (Audited) \| item	3,400
Short-duration Insurance Contracts, Accident Year 2019 [Member] \| Bond & Specialty Insurance [Member] \| Fidelity and surety [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	$ 203
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	49
IBNR Reserves Dec. 31, 2019 (Audited)	$ 116
Cumulative Number of Reported Claims (Audited) \| item	592
Short-duration Insurance Contracts, Accident Year 2019 [Member] \| Personal Insurance [Member] \| Automobile [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	$ 3,362
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	1,933
IBNR Reserves Dec. 31, 2019 (Audited)	$ 858
Cumulative Number of Reported Claims (Audited) \| item	940,933
Short-duration Insurance Contracts, Accident Year 2019 [Member] \| Personal Insurance [Member] \| Homeowners (excluding Other) [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	$ 2,297
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	1,613
IBNR Reserves Dec. 31, 2019 (Audited)	$ 447
Cumulative Number of Reported Claims (Audited) \| item	158,328
Short-duration Insurance Contracts, Accident Year 2019 [Member] \| Personal Insurance [Member] \| International - Canada [Member] \| Property-casualty [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	$ 445
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2019)	216
IBNR Reserves Dec. 31, 2019 (Audited)	$ 110
Cumulative Number of Reported Claims (Audited) \| item	44,796

Insurance Claim Reserves (Det_5

Insurance Claim Reserves (Details) - Historical Claim Duration	Dec. 31, 2019
Business Insurance [Member] \| General liability [Member]
Historical Claims Duration
Short-duration Insurance Contracts, Historical Claims Duration, Year One	3.60%
Short-duration Insurance Contracts, Historical Claims Duration, Year Two	12.60%
Short-duration Insurance Contracts, Historical Claims Duration, Year Three	18.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Four	18.90%
Short-duration Insurance Contracts, Historical Claims Duration, Year Five	14.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Six	9.80%
Short-duration Insurance Contracts, Historical Claims Duration, Year Seven	5.80%
Short-duration Insurance Contracts, Historical Claims Duration, Year Eight	4.30%
Short-duration Insurance Contracts, Historical Claims Duration, Year Nine	2.10%
Short-duration Insurance Contracts, Historical Claims Duration, Year Ten	1.60%
Business Insurance [Member] \| Commercial property [Member]
Historical Claims Duration
Short-duration Insurance Contracts, Historical Claims Duration, Year One	53.60%
Short-duration Insurance Contracts, Historical Claims Duration, Year Two	32.60%
Short-duration Insurance Contracts, Historical Claims Duration, Year Three	7.50%
Short-duration Insurance Contracts, Historical Claims Duration, Year Four	2.50%
Short-duration Insurance Contracts, Historical Claims Duration, Year Five	2.50%
Business Insurance [Member] \| Commercial multi-peril [Member]
Historical Claims Duration
Short-duration Insurance Contracts, Historical Claims Duration, Year One	38.90%
Short-duration Insurance Contracts, Historical Claims Duration, Year Two	23.20%
Short-duration Insurance Contracts, Historical Claims Duration, Year Three	10.80%
Short-duration Insurance Contracts, Historical Claims Duration, Year Four	9.30%
Short-duration Insurance Contracts, Historical Claims Duration, Year Five	6.20%
Short-duration Insurance Contracts, Historical Claims Duration, Year Six	3.50%
Short-duration Insurance Contracts, Historical Claims Duration, Year Seven	1.90%
Short-duration Insurance Contracts, Historical Claims Duration, Year Eight	1.30%
Short-duration Insurance Contracts, Historical Claims Duration, Year Nine	0.70%
Short-duration Insurance Contracts, Historical Claims Duration, Year Ten	0.30%
Business Insurance [Member] \| Automobile [Member]
Historical Claims Duration
Short-duration Insurance Contracts, Historical Claims Duration, Year One	29.80%
Short-duration Insurance Contracts, Historical Claims Duration, Year Two	19.20%
Short-duration Insurance Contracts, Historical Claims Duration, Year Three	17.90%
Short-duration Insurance Contracts, Historical Claims Duration, Year Four	14.70%
Short-duration Insurance Contracts, Historical Claims Duration, Year Five	9.50%
Business Insurance [Member] \| Workers' compensation [Member]
Historical Claims Duration
Short-duration Insurance Contracts, Historical Claims Duration, Year One	17.80%
Short-duration Insurance Contracts, Historical Claims Duration, Year Two	19.70%
Short-duration Insurance Contracts, Historical Claims Duration, Year Three	11.20%
Short-duration Insurance Contracts, Historical Claims Duration, Year Four	7.20%
Short-duration Insurance Contracts, Historical Claims Duration, Year Five	5.10%
Short-duration Insurance Contracts, Historical Claims Duration, Year Six	3.70%
Short-duration Insurance Contracts, Historical Claims Duration, Year Seven	2.80%
Short-duration Insurance Contracts, Historical Claims Duration, Year Eight	2.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Nine	1.70%
Short-duration Insurance Contracts, Historical Claims Duration, Year Ten	1.30%
Bond & Specialty Insurance [Member] \| General liability [Member]
Historical Claims Duration
Short-duration Insurance Contracts, Historical Claims Duration, Year One	7.20%
Short-duration Insurance Contracts, Historical Claims Duration, Year Two	22.10%
Short-duration Insurance Contracts, Historical Claims Duration, Year Three	19.50%
Short-duration Insurance Contracts, Historical Claims Duration, Year Four	16.20%
Short-duration Insurance Contracts, Historical Claims Duration, Year Five	10.90%
Short-duration Insurance Contracts, Historical Claims Duration, Year Six	7.90%
Short-duration Insurance Contracts, Historical Claims Duration, Year Seven	4.10%
Short-duration Insurance Contracts, Historical Claims Duration, Year Eight	3.10%
Short-duration Insurance Contracts, Historical Claims Duration, Year Nine	1.20%
Short-duration Insurance Contracts, Historical Claims Duration, Year Ten	0.60%
Bond & Specialty Insurance [Member] \| Fidelity and surety [Member]
Historical Claims Duration
Short-duration Insurance Contracts, Historical Claims Duration, Year One	26.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Two	37.30%
Short-duration Insurance Contracts, Historical Claims Duration, Year Three	10.10%
Short-duration Insurance Contracts, Historical Claims Duration, Year Four	1.30%
Short-duration Insurance Contracts, Historical Claims Duration, Year Five	1.30%
Personal Insurance [Member] \| Automobile [Member]
Historical Claims Duration
Short-duration Insurance Contracts, Historical Claims Duration, Year One	58.50%
Short-duration Insurance Contracts, Historical Claims Duration, Year Two	20.90%
Short-duration Insurance Contracts, Historical Claims Duration, Year Three	9.70%
Short-duration Insurance Contracts, Historical Claims Duration, Year Four	5.50%
Short-duration Insurance Contracts, Historical Claims Duration, Year Five	2.90%
Personal Insurance [Member] \| Homeowners (excluding Other) [Member]
Historical Claims Duration
Short-duration Insurance Contracts, Historical Claims Duration, Year One	67.10%
Short-duration Insurance Contracts, Historical Claims Duration, Year Two	24.10%
Short-duration Insurance Contracts, Historical Claims Duration, Year Three	4.80%
Short-duration Insurance Contracts, Historical Claims Duration, Year Four	1.70%
Short-duration Insurance Contracts, Historical Claims Duration, Year Five	0.60%
Personal Insurance [Member] \| International - Canada [Member] \| Property-casualty [Member]
Historical Claims Duration
Short-duration Insurance Contracts, Historical Claims Duration, Year One	45.50%
Short-duration Insurance Contracts, Historical Claims Duration, Year Two	18.40%
Short-duration Insurance Contracts, Historical Claims Duration, Year Three	8.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Four	7.80%
Short-duration Insurance Contracts, Historical Claims Duration, Year Five	7.40%
Short-duration Insurance Contracts, Historical Claims Duration, Year Six	5.20%
Short-duration Insurance Contracts, Historical Claims Duration, Year Seven	3.60%
Short-duration Insurance Contracts, Historical Claims Duration, Year Eight	1.90%
Short-duration Insurance Contracts, Historical Claims Duration, Year Nine	1.10%
Short-duration Insurance Contracts, Historical Claims Duration, Year Ten	0.70%

Insurance Claim Reserves Insura

Insurance Claim Reserves Insurance Claim Reserves (Details) - Asbestos and Environmental Reserves - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Liability for claims and claim adjustment expense
Asbestos and environmental claims reserves, balance	$ 1,600	$ 1,620
Asbestos reserves [Member]
Liability for claims and claim adjustment expense
Increase to asbestos and environmental reserves	220	225	$ 225
Net losses paid	$ 224	$ 225	$ 271
Percent of total asbestos net paid losses related to policyholders with whom the Company had entered into settlement agreements limiting the Company's liability	4.00%	9.00%	4.00%
Environmental reserves [Member]
Liability for claims and claim adjustment expense
Increase to asbestos and environmental reserves	$ 76	$ 55	$ 65

Debt (Details)

Debt (Details) - USD ($) $ in Millions	Dec. 31, 2019	Jun. 02, 2019	Mar. 04, 2019	Dec. 31, 2018	Mar. 07, 2018	May 22, 2017
Schedule of debt
Commercial paper	$ 100			$ 100
Total short-term debt	600			600
Total long-term debt	6,004			6,004
Total debt principal	6,604			6,604
Unamortized fair value adjustment	43			44
Unamortized debt issuance costs	(89)			(84)
Total debt	6,558			6,564
Senior Notes [Member] \| 3.90% Senior notes due November 1, 2020 [Member]
Schedule of debt
Current maturities of long-term debt	500			0
Total long-term debt	$ 0			$ 500
Interest rate (percent)	3.90%			3.90%
Senior Notes [Member] \| 5.90% Senior notes due June 2, 2019 [Member]
Schedule of debt
Current maturities of long-term debt	$ 0			$ 500
Interest rate (percent)		5.90%		5.90%
Senior Notes [Member] \| 7.75% Senior notes due April 15, 2026 [Member]
Schedule of debt
Total long-term debt	$ 200			$ 200
Interest rate (percent)	7.75%			7.75%
Senior Notes [Member] \| 6.375% Senior notes due March 15, 2033 [Member]
Schedule of debt
Total long-term debt	$ 500			$ 500
Interest rate (percent)	6.375%			6.375%
Senior Notes [Member] \| 6.75% Senior notes due June 20, 2036 [Member]
Schedule of debt
Total long-term debt	$ 400			$ 400
Interest rate (percent)	6.75%			6.75%
Senior Notes [Member] \| 6.25% Senior notes due June 15, 2037 [Member]
Schedule of debt
Total long-term debt	$ 800			$ 800
Interest rate (percent)	6.25%			6.25%
Senior Notes [Member] \| 5.35% Senior notes due November 1, 2040 [Member]
Schedule of debt
Total long-term debt	$ 750			$ 750
Interest rate (percent)	5.35%			5.35%
Senior Notes [Member] \| 4.60% Senior notes due August 1, 2043 [Member]
Schedule of debt
Total long-term debt	$ 500			$ 500
Interest rate (percent)	4.60%			4.60%
Senior Notes [Member] \| 4.30% Senior notes due August 25, 2045 [Member]
Schedule of debt
Total long-term debt	$ 400			$ 400
Interest rate (percent)	4.30%			4.30%
Senior Notes [Member] \| 3.75% Senior notes due May 15, 2046 [Member]
Schedule of debt
Total long-term debt	$ 500			$ 500
Interest rate (percent)	3.75%			3.75%
Senior Notes [Member] \| 4.00% Senior notes due May 30, 2047 [Member]
Schedule of debt
Total long-term debt	$ 700			$ 700
Interest rate (percent)	4.00%			4.00%		4.00%
Senior Notes [Member] \| 4.05% Senior notes due March 7, 2048 [Member]
Schedule of debt
Total long-term debt	$ 500			$ 500
Interest rate (percent)	4.05%			4.05%	4.05%
Senior Notes [Member] \| 4.10% Senior notes due March 4, 2049 [Member]
Schedule of debt
Total long-term debt	$ 500
Interest rate (percent)	4.10%		4.10%
Junior Subordinated Debt [Member] \| 7.625% Junior subordinated debentures due December 15, 2027 [Member]
Schedule of debt
Total long-term debt	$ 125			$ 125
Unamortized fair value adjustment	$ 11			$ 12
Interest rate (percent)	7.625%			7.625%
Junior Subordinated Debt [Member] \| 8.50% Junior subordinated debentures due December 15, 2045 [Member]
Schedule of debt
Total long-term debt	$ 56			$ 56
Unamortized fair value adjustment	$ 14			$ 14
Interest rate (percent)	8.50%			8.50%
Junior Subordinated Debt [Member] \| 8.312% Junior subordinated debentures due July 1, 2046 [Member]
Schedule of debt
Total long-term debt	$ 73			$ 73
Unamortized fair value adjustment	$ 18			$ 18
Interest rate (percent)	8.312%			8.312%

Debt (Details) - Debt Issuance

Debt (Details) - Debt Issuance - USD ($) $ in Millions	Mar. 04, 2019	Mar. 07, 2018	May 22, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Debt Instrument
Net proceeds of issuance, after the deduction of the underwriting discount and expenses				$ 492	$ 591	$ 789
Senior Notes [Member] \| 4.10% Senior notes due March 4, 2049 [Member]
Debt Instrument
Debt, principal amount	$ 500
Interest rate (percent)	4.10%			4.10%
Net proceeds of issuance, after the deduction of the underwriting discount and expenses	$ 492
Percentage of principal amount at which redemption price may be set	100.00%
Basis points added to current Treasury rate used in calculation of alternative redemption price	0.20%
Senior Notes [Member] \| 4.05% Senior notes due March 7, 2048 [Member]
Debt Instrument
Debt, principal amount		$ 500
Interest rate (percent)		4.05%		4.05%	4.05%
Net proceeds of issuance, after the deduction of the underwriting discount and expenses		$ 491
Percentage of principal amount at which redemption price may be set		100.00%
Basis points added to current Treasury rate used in calculation of alternative redemption price		0.15%
Senior Notes [Member] \| 4.00% Senior notes due May 30, 2047 [Member]
Debt Instrument
Debt, principal amount			$ 700
Interest rate (percent)			4.00%	4.00%	4.00%
Net proceeds of issuance, after the deduction of the underwriting discount and expenses			$ 689
Percentage of principal amount at which redemption price may be set			100.00%
Basis points added to current Treasury rate used in calculation of alternative redemption price			0.15%

Debt (Details) - Repayment

Debt (Details) - Repayment - USD ($) $ in Millions	Jun. 02, 2019	May 15, 2018	Dec. 15, 2017	Jun. 02, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Debt Instrument
Debt, principal amount repaid					$ 500	$ 600	$ 657
Senior Notes [Member] \| 5.90% Senior notes due June 2, 2019 [Member]
Debt Instrument
Debt, principal amount repaid	$ 500
Interest rate (percent)	5.90%					5.90%
Senior Notes [Member] \| 5.80% Senior notes due May 15, 2018 [Member]
Debt Instrument
Debt, principal amount repaid		$ 500
Interest rate (percent)		5.80%
Senior Notes [Member] \| 5.75% Senior notes due December 15, 2017 [Member]
Debt Instrument
Debt, principal amount repaid			$ 450
Interest rate (percent)			5.75%
Junior Subordinated Debt [Member] \| 6.25% Fixed-to-floating rate junior subordinated debentures due March 15, 2067 [Member]
Debt Instrument
Debt, principal amount repaid				$ 107
Interest rate (percent)				6.25%
Percentage of principal amount at which redemption price was set				100.00%

Debt (Details) - Commercial Pap

Debt (Details) - Commercial Paper - Commercial Paper [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Line of Credit Facility
Credit agreement, maximum borrowing capacity	$ 800
Minimum [Member]
Line of Credit Facility
Interest rate on commercial paper	1.58%	1.47%
Maximum [Member]
Line of Credit Facility
Interest rate on commercial paper	2.48%	2.37%

Debt (Details) - Junior Subordi

Debt (Details) - Junior Subordinated Debt $ in Millions	12 Months Ended
Debt (Details) - Junior Subordinated Debt $ in Millions	Dec. 31, 2019USD ($)trustsdebenture_instruments	Dec. 31, 2018USD ($)
Debt Instrument
Unamortized fair value adjustment	$ 43	$ 44
Amount of certain debt obligations of Travelers Property Casualty Corp. (TPC) and Travelers Insurance Group Holdings, Inc. (TIGHI) that are fully and unconditionally guaranteed by The Travelers Companies, Inc.	$ 700
Junior Subordinated Debt [Member]
Debt Instrument
Number of junior subordinated debentures that are all similar in nature \| debenture_instruments	3
Number of separate trusts that issued preferred securities and used proceeds to purchase the Company's subordinated debentures \| trusts	3
Impact of amortization of the fair value adjustment on interest expense	$ 1	$ 2
Junior Subordinated Debt [Member] \| 7.625% Junior subordinated debentures due December 15, 2027 [Member]
Debt Instrument
Interest rate (percent)	7.625%	7.625%
Effective interest rate (percent)	6.147%
Unamortized fair value adjustment	$ 11	$ 12
Junior Subordinated Debt [Member] \| 8.50% Junior subordinated debentures due December 15, 2045 [Member]
Debt Instrument
Interest rate (percent)	8.50%	8.50%
Effective interest rate (percent)	6.362%
Unamortized fair value adjustment	$ 14	$ 14
Junior Subordinated Debt [Member] \| 8.312% Junior subordinated debentures due July 1, 2046 [Member]
Debt Instrument
Interest rate (percent)	8.312%	8.312%
Effective interest rate (percent)	6.362%
Unamortized fair value adjustment	$ 18	$ 18
Senior Notes [Member] \| 7.75% Senior notes due April 15, 2026 [Member]
Debt Instrument
Interest rate (percent)	7.75%	7.75%
Amount of certain debt obligations of Travelers Property Casualty Corp. (TPC) and Travelers Insurance Group Holdings, Inc. (TIGHI) that are fully and unconditionally guaranteed by The Travelers Companies, Inc.	$ 200
Senior Notes [Member] \| 6.375% Senior notes due March 15, 2033 [Member]
Debt Instrument
Interest rate (percent)	6.375%	6.375%
Amount of certain debt obligations of Travelers Property Casualty Corp. (TPC) and Travelers Insurance Group Holdings, Inc. (TIGHI) that are fully and unconditionally guaranteed by The Travelers Companies, Inc.	$ 500

Debt (Details) - Maturities

Debt (Details) - Maturities	Dec. 31, 2019USD ($)
Maturities of long-term debt
Amount of debt obligations, other than commercial paper, due in 2020	$ 500,000,000
Amount of debt obligations, other than commercial paper, due in 2021	0
Amount of debt obligations, other than commercial paper, due in 2022	0
Amount of debt obligations, other than commercial paper, due in 2023	0
Amount of debt obligations, other than commercial paper, due in 2024	$ 0

Debt (Details) - Line of Credit

Debt (Details) - Line of Credit - Line of credit [Member] - Revolving Credit Agreement Due to Expire on June 4, 2023 [Member] $ in Millions	12 Months Ended
	Dec. 31, 2019USD ($)
Line of Credit Facility
Credit agreement, term (in years)	5 years
Credit agreement, maximum borrowing capacity	$ 1,000
Credit agreement, covenant terms	Pursuant to the credit agreement covenants, the Company must maintain a minimum consolidated net worth, defined as shareholders’ equity determined in accordance with GAAP (excluding accumulated other comprehensive income (loss)) plus (a) trust preferred securities (not to exceed 15% of total capital) and (b) mandatorily convertible securities (combined with trust preferred securities, not to exceed 25% of total capital) less goodwill and other intangible assets. The threshold is adjusted downward by an amount equal to 70% of the aggregate amount of common stock repurchased by the Company after March 31, 2018, up to a maximum deduction of $1.75 billion. The threshold was $12.55 billion at December 31, 2019 and could decline to a minimum of $12.494 billion during the term of the credit agreement, subject to the Company repurchasing an additional $80 million of its common stock. In addition, the credit agreement contains other customary restrictive covenants as well as certain customary events of default, including with respect to a change in control, which is defined to include the acquisition of 35% or more of the Company’s voting stock and certain changes in the composition of the Company’s Board of Directors.
Maximum percentage of trust preferred securities relative to total capital in determining consolidated net worth	15.00%
Maximum percentage of trust preferred securities and mandatorily convertible securities relative to total capital in determining consolidated net worth	25.00%
Credit agreement, threshold of consolidated net worth	$ 12,550
Percentage of aggregate amount of common stock repurchased by the Company after March 31, 2018 by which the threshold is adjusted downward	70.00%
Maximum downward adjustment to threshold relative to common stock repurchases	$ 1,750
Common stock repurchases required during the term of the credit agreement to reduce threshold net worth to minimum amount reported	$ 80
Credit agreement, compliance	At December 31, 2019, the Company was in compliance with these covenants.
Minimum [Member]
Line of Credit Facility
Credit agreement, threshold of consolidated net worth	$ 12,494
Percentage of Company's voting stock acquired by outside entity that would be considered a change in control	35.00%
LIBOR [Member]
Line of Credit Facility
Credit agreement, cost of borrowing, basis points above LIBOR	1.00%
LIBOR [Member] \| Minimum [Member]
Line of Credit Facility
Credit agreement, cost of borrowing, basis points above LIBOR	0.75%
LIBOR [Member] \| Maximum [Member]
Line of Credit Facility
Credit agreement, cost of borrowing, basis points above LIBOR	1.375%

Shareholders' Equity and Divi_3

Shareholders' Equity and Dividend Availability Shareholders' Equity and Dividend Availability (Details) - USD ($)	3 Months Ended				12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2019	Dec. 31, 2018	Apr. 30, 2017
Stockholders' Equity Note [Abstract]
Number of authorized shares (in shares)	1,755,000,000				1,755,000,000
Number of authorized shares, preferred shares (in shares)	5,000,000				5,000,000
Number of authorized shares, voting common stock (in shares)	1,745,000,000				1,745,000,000
Number of authorized shares, undesignated shares (in shares)	5,000,000				5,000,000
Additional share repurchase authorization							$ 5,000,000,000
Number of shares repurchased (in shares)	2,800,000	2,500,000	2,600,000	2,900,000	10,800,000
Cost of shares repurchased	$ 375,000,000	$ 375,000,000	$ 375,000,000	$ 375,000,000	$ 1,500,000,000
Average price paid per share (in dollars per share)	$ 134.33	$ 147.23	$ 145.87	$ 129.42	$ 138.80
Remaining capacity under share repurchase authorization	$ 1,786,000,000	$ 2,161,000,000	$ 2,536,000,000	$ 2,911,000,000	$ 1,786,000,000
Cost of shares acquired to cover tax withholding costs and exercise costs					$ 48,000,000	$ 51,000,000

Shareholders' Equity and Divi_4

Shareholders' Equity and Dividend Availability (Details) - Business Acquisition - shares	Dec. 31, 2019	Dec. 31, 2017
Simply Business [Member] \| Restricted common stock [Member]
Business Acquisition
Shares outstanding and unvested	41,997	95,953

Shareholders' Equity and Divi_5

Shareholders' Equity and Dividend Availability (Details) - Dividend Availability $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2019USD ($)item$ / shares	Dec. 31, 2018USD ($)item$ / shares	Dec. 31, 2017USD ($)item$ / shares
Statutory accounting principles
Dividends received by TRV and its two non-insurance holding companies from their U.S. insurance subsidiaries	$ 2,500	$ 2,300	$ 2,330
Cash dividends paid	844	814	785
Insurance subsidiaries [Member]
Statutory accounting principles
Statutory net income of the Company's domestic and international insurance subsidiaries	2,740	2,610	$ 2,300
Statutory capital and surplus of the Company's domestic and international insurance subsidiaries	$ 21,330	$ 20,770
Travelers [Member]
Statutory accounting principles
Number of non-insurance holding companies underneath TRV \| item	2	2	2
Cash dividends declared per common share (in dollars per share) \| $ / shares	$ 3.23	$ 3.03	$ 2.83
Cash dividends paid	$ 844	$ 814	$ 785
Connecticut Insurance Department [Member] \| Insurance subsidiaries [Member]
Statutory accounting principles
Maximum amount of dividends available to be paid by subsidiaries to their parent without prior approval of the Connecticut Insurance Department	$ 2,790

Other Comprehensive Income an_3

Other Comprehensive Income and Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	Jan. 01, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Accumulated other comprehensive income [Roll Forward]
Balance, beginning of year	$ 23,731	$ 22,894	$ 23,731
Other comprehensive income (loss), net of taxes		2,499	(1,470)	$ 412
Balance, end of year		25,943	22,894	23,731
Pre-tax components of other comprehensive income (loss) and related tax expense (benefit)
Other comprehensive income (loss) before income taxes		3,140	(1,819)	522
Income tax expense (benefit)		641	(349)	110
Other comprehensive income (loss), net of taxes		2,499	(1,470)	412
Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated other comprehensive income [Roll Forward]
Balance, beginning of year	(343)	(1,859)	(343)	(755)
Cumulative effect of adoption of updated accounting guidance for equity financial instruments, pre-tax	(34)
Cumulative effect of adoption of updated accounting guidance for equity financial instruments, tax	(12)
Cumulative effect of adoption of updated accounting guidance for equity financial instruments, net of income taxes	(22)			(22)
Reclassification of certain tax effects from adoption of updated accounting guidance	(24)		(24)
Effect of adoption of updated accounting guidance, net of tax, total	(46)
Other comprehensive income (loss) before reclassifications		2,494	(1,513)	518
Amounts reclassified from accumulated other comprehensive income		5	43	(106)
Other comprehensive income (loss), net of taxes		2,499	(1,470)	412
Balance, end of year		640	(1,859)	(343)
Pre-tax components of other comprehensive income (loss) and related tax expense (benefit)
Other comprehensive income (loss) before income taxes		3,140	(1,819)	522
Income tax expense (benefit)		641	(349)	110
Other comprehensive income (loss), net of taxes		2,499	(1,470)	412
Changes in Net Unrealized Gains (Losses) on Investment Securities Having No Credit Losses Recognized in the Consolidated Statement of Income [Member]
Accumulated other comprehensive income [Roll Forward]
Balance, beginning of year	747	(306)	747	528
Cumulative effect of adoption of updated accounting guidance for equity financial instruments, pre-tax	(34)
Cumulative effect of adoption of updated accounting guidance for equity financial instruments, tax	(12)
Cumulative effect of adoption of updated accounting guidance for equity financial instruments, net of income taxes	(22)
Reclassification of certain tax effects from adoption of updated accounting guidance	145
Effect of adoption of updated accounting guidance, net of tax, total	123
Other comprehensive income (loss) before reclassifications		2,406	(1,151)	367
Amounts reclassified from accumulated other comprehensive income		(43)	(25)	(148)
Other comprehensive income (loss), net of taxes		2,363	(1,176)	219
Balance, end of year		2,057	(306)	747
Pre-tax components of other comprehensive income (loss) and related tax expense (benefit)
Other comprehensive income (loss) before income taxes		2,994	(1,489)	294
Income tax expense (benefit)		631	(313)	75
Other comprehensive income (loss), net of taxes		2,363	(1,176)	219
Changes in Net Unrealized Gains (Losses) on Investment Securities Having Credit Losses Recognized in the Consolidated Statement of Income [Member]
Accumulated other comprehensive income [Roll Forward]
Balance, beginning of year	207	193	207	202
Cumulative effect of adoption of updated accounting guidance for equity financial instruments, pre-tax	0
Cumulative effect of adoption of updated accounting guidance for equity financial instruments, tax	0
Cumulative effect of adoption of updated accounting guidance for equity financial instruments, net of income taxes	0
Reclassification of certain tax effects from adoption of updated accounting guidance	7
Effect of adoption of updated accounting guidance, net of tax, total	7
Other comprehensive income (loss) before reclassifications		(4)	(21)	4
Amounts reclassified from accumulated other comprehensive income		0	0	1
Other comprehensive income (loss), net of taxes		(4)	(21)	5
Balance, end of year		189	193	207
Pre-tax components of other comprehensive income (loss) and related tax expense (benefit)
Other comprehensive income (loss) before income taxes		(4)	(27)	8
Income tax expense (benefit)		0	(6)	3
Other comprehensive income (loss), net of taxes		(4)	(21)	5
Net Benefit Plan Assets and Obligations Recognized in Shareholders’ Equity [Member]
Accumulated other comprehensive income [Roll Forward]
Balance, beginning of year	(686)	(873)	(686)	(703)
Cumulative effect of adoption of updated accounting guidance for equity financial instruments, pre-tax	0
Cumulative effect of adoption of updated accounting guidance for equity financial instruments, tax	0
Cumulative effect of adoption of updated accounting guidance for equity financial instruments, net of income taxes	0
Reclassification of certain tax effects from adoption of updated accounting guidance	(141)
Effect of adoption of updated accounting guidance, net of tax, total	(141)
Other comprehensive income (loss) before reclassifications		(14)	(114)	(24)
Amounts reclassified from accumulated other comprehensive income		41	68	41
Other comprehensive income (loss), net of taxes		27	(46)	17
Balance, end of year		(846)	(873)	(686)
Pre-tax components of other comprehensive income (loss) and related tax expense (benefit)
Other comprehensive income (loss) before income taxes		33	(56)	29
Income tax expense (benefit)		6	(10)	12
Other comprehensive income (loss), net of taxes		27	(46)	17
Net Unrealized Foreign Currency Translation [Member]
Accumulated other comprehensive income [Roll Forward]
Balance, beginning of year	(611)	(873)	(611)	(782)
Cumulative effect of adoption of updated accounting guidance for equity financial instruments, pre-tax	0
Cumulative effect of adoption of updated accounting guidance for equity financial instruments, tax	0
Cumulative effect of adoption of updated accounting guidance for equity financial instruments, net of income taxes	0
Reclassification of certain tax effects from adoption of updated accounting guidance	(35)
Effect of adoption of updated accounting guidance, net of tax, total	$ (35)
Other comprehensive income (loss) before reclassifications		106	(227)	171
Amounts reclassified from accumulated other comprehensive income		7	0	0
Other comprehensive income (loss), net of taxes		113	(227)	171
Balance, end of year		(760)	(873)	(611)
Pre-tax components of other comprehensive income (loss) and related tax expense (benefit)
Other comprehensive income (loss) before income taxes		117	(247)	191
Income tax expense (benefit)		4	(20)	20
Other comprehensive income (loss), net of taxes		$ 113	$ (227)	$ 171

Other Comprehensive Income an_4

Other Comprehensive Income and Accumulated Other Comprehensive Income (Details) - Reclassifications - USD ($) $ in Millions		3 Months Ended								12 Months Ended
		Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Reclassification Adjustment out of Accumulated Other Comprehensive Income
Reclassification adjustment impacting net realized investment gains on the income statement	[1]									$ (113)	$ (114)	$ (216)
Reclassification adjustment impacting claims and claim adjustment expenses on the income statement										19,133	18,291	17,467
Reclassification adjustment impacting general and administrative expense on the income statement										4,365	4,297	4,170
Total reclassifications		$ (1,074)	$ (432)	$ (665)	$ (967)	$ (746)	$ (806)	$ (631)	$ (778)	(3,138)	(2,961)	(2,730)
Income tax (expense) benefit		(201)	(36)	(108)	(171)	(125)	(97)	(107)	(109)	(516)	(438)	(674)
Amounts reclassified from accumulated other comprehensive income, net of taxes		$ (873)	$ (396)	$ (557)	$ (796)	$ (621)	$ (709)	$ (524)	$ (669)	(2,622)	(2,523)	(2,056)
Accumulated Other Comprehensive Income (Loss) [Member] \| Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income
Total reclassifications										4	54	(147)
Income tax (expense) benefit										(1)	11	(41)
Amounts reclassified from accumulated other comprehensive income, net of taxes										5	43	(106)
Changes in Net Unrealized Gains (Losses) on Investment Securities Having No Credit Losses Recognized in the Consolidated Statement of Income [Member] \| Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income
Reclassification adjustment impacting net realized investment gains on the income statement										(55)	(32)	(228)
Income tax (expense) benefit										(12)	(7)	(80)
Amounts reclassified from accumulated other comprehensive income, net of taxes										(43)	(25)	(148)
Changes in Net Unrealized Gains (Losses) on Investment Securities Having Credit Losses Recognized in the Consolidated Statement of Income [Member] \| Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income
Reclassification adjustment impacting net realized investment gains on the income statement										0	0	1
Income tax (expense) benefit										0	0	0
Amounts reclassified from accumulated other comprehensive income, net of taxes										0	0	1
Net Benefit Plan Assets and Obligations Recognized in Shareholders’ Equity [Member] \| Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income
Reclassification adjustment impacting claims and claim adjustment expenses on the income statement										21	35	32
Reclassification adjustment impacting general and administrative expense on the income statement										31	51	48
Total reclassifications										52	86	80
Income tax (expense) benefit										11	18	39
Amounts reclassified from accumulated other comprehensive income, net of taxes										41	68	41
Net Unrealized Foreign Currency Translation [Member] \| Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income
Reclassification adjustment impacting net realized investment gains on the income statement										7	0	0
Income tax (expense) benefit										0	0	0
Amounts reclassified from accumulated other comprehensive income, net of taxes										$ 7	$ 0	$ 0

[1]	Total other-than-temporary impairment (OTTI) losses were $(3) million , $(1) million and $(13) million for the years ended December 31, 2019 , 2018 and 2017 , respectively. Of total OTTI, credit losses of $(4) million , $(1) million and $(14) million for the years ended December 31, 2019 , 2018 and 2017 , respectively, were recognized in net realized investment gains. In addition, unrealized gains (losses) from other changes in total OTTI of $1 million , $0 million and $1 million for the years ended December 31, 2019 , 2018 and 2017 , respectively, were recognized in other comprehensive income (loss) as part of changes in net unrealized gains (losses) on investment securities having credit losses recognized in the consolidated statement of income.

Earnings per Share (Details)

Earnings per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Earnings Per Share Reconciliation [Abstract]
Net income	$ 873	$ 396	$ 557	$ 796	$ 621	$ 709	$ 524	$ 669	$ 2,622	$ 2,523	$ 2,056
Participating securities — allocated income									(19)	(19)	(15)
Net income available to common shareholders -- basic									2,603	2,504	2,041
Net income available to common shareholders -- diluted									$ 2,603	$ 2,504	$ 2,041
Weighted average shares outstanding, basic (in shares)									260	267.4	276
Weighted average effects of dilutive securities - stock options and performance shares (in shares)									2.3	2.4	2.6
Weighted average shares outstanding, diluted (in shares)									262.3	269.8	278.6
Net income per common share, basic (in dollars per share)	$ 3.37	$ 1.52	$ 2.11	$ 3.01	$ 2.33	$ 2.65	$ 1.93	$ 2.45	$ 10.01	$ 9.37	$ 7.39
Net income per common share, diluted (in dollars per share)	$ 3.35	$ 1.50	$ 2.10	$ 2.99	$ 2.32	$ 2.62	$ 1.92	$ 2.42	$ 9.92	$ 9.28	$ 7.33

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
Income Taxes (Details) - USD ($) $ in Millions	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Current income tax expense included in consolidated statement of income, federal									$ 546	$ 424
Current income tax expense included in consolidated statement of income, federal (excluding impact of TCJA)											$ 314
Current income tax expense included in consolidated statement of income, impact of TCJA at enactment											21
Current income tax expense included in consolidated statement of income, foreign									7	41	56
Current income tax expense included in consolidated statement of income, state									6	8	4
Total current tax expense									559	473	395
Deferred income tax expense included in consolidated statement of income, federal									(33)	(13)	337
Deferred income tax expense included in consolidated statement of income, federal (excluding impact of TCJA)											229
Deferred income tax expense included in consolidated statement of income, impact of TCJA at enactment											108
Deferred income tax expense included in consolidated statement of income, foreign									(10)	(22)	(58)
Total deferred tax expense (benefit)									(43)	(35)	279
Total income tax expense included in the consolidated statement of income	$ 201	$ 36	$ 108	$ 171	$ 125	$ 97	$ 107	$ 109	516	438	674
Expense (benefit) relating to changes in the unrealized gain (loss) on investments, unrealized loss on foreign exchange and other items in other comprehensive income (loss)									641	(349)	110
Total income tax expense included in the consolidated financial statements									$ 1,157	$ 89	$ 784

Income Taxes (Details) - Effect

Income Taxes (Details) - Effective Tax Rate - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
U.S. income before income taxes									$ 3,211	$ 3,039	$ 2,798
Foreign income (loss) before income taxes									(73)	(78)	(68)
Income before income taxes	$ 1,074	$ 432	$ 665	$ 967	$ 746	$ 806	$ 631	$ 778	$ 3,138	$ 2,961	$ 2,730
Statutory tax rate (percent)									21.00%	21.00%	35.00%
Expected federal income tax expense									$ 659	$ 622	$ 956
Tax effect of nontaxable investment income									(149)	(150)	(297)
Tax effect of TCJA at enactment											129
Tax effect of other, net									6	(34)	(114)
Total income tax expense included in the consolidated statement of income	201	$ 36	$ 108	$ 171	125	$ 97	$ 107	$ 109	$ 516	$ 438	$ 674
Effective tax rate (percent)									16.00%	15.00%	25.00%
Income taxes paid									$ 428	$ 408	$ 514
Current income tax payable	126								126
Current income tax receivable					$ 12					$ 12
Net charge included in total income tax expense related to TCJA at the date of enactment											$ 129
Estimated additional annual tax payments relating to the discounted reserves transitional adjustment associated with TCJA	$ 19								$ 19

Income Taxes (Details) - Deferr

Income Taxes (Details) - Deferred Tax Asset and Liability - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Deferred tax assets, claims and claim adjustment expense reserves	$ 551	$ 571
Deferred tax assets, unearned premium reserves	539	503
Deferred tax assets, compensation-related liabilities	97	92
Deferred tax assets, other	243	200
Total gross deferred tax assets	1,430	1,366
Less: valuation allowance	27	8
Adjusted gross deferred tax assets	1,403	1,358
Deferred tax liabilities, claims and claim adjustment expense reserve discounting (transition rule)	115	159
Deferred tax liabilities, deferred acquisition costs	427	397
Deferred tax liabilities, investments	781	152
Deferred tax liabilities, internally developed software	94	92
Deferred tax liabilities, depreciation	70	67
Deferred tax liabilities, other	53	46
Total gross deferred tax liabilities	1,540	913
Net deferred tax (liability)	$ (137)
Net deferred tax asset		$ 445

Income Taxes Income Taxes (Deta

Income Taxes Income Taxes (Details) - Valuation Allowance $ in Millions	12 Months Ended
	Dec. 31, 2019USD ($)
Valuation Allowance
Increase in valuation allowance	$ 19
Subsidiary [Member] \| Republic of Ireland [Member]
Valuation Allowance
Increase in valuation allowance	16
Subsidiary [Member] \| Brazil [Member]
Valuation Allowance
Increase in valuation allowance	2
Subsidiary [Member] \| Canada [Member]
Valuation Allowance
Increase in valuation allowance	$ 1

Income Taxes (Details) - NOL Ca

Income Taxes (Details) - NOL Carryforwards $ in Millions	Dec. 31, 2019USD ($)
United States [Member]
Net Operating Loss Carryforward
Net operating loss carryforward	$ 2
Brazil [Member]
Net Operating Loss Carryforward
Net operating loss carryforward	25
Canada [Member]
Net Operating Loss Carryforward
Net operating loss carryforward	5
Republic of Ireland [Member]
Net Operating Loss Carryforward
Net operating loss carryforward	124
United Kingdom [Member]
Net Operating Loss Carryforward
Net operating loss carryforward	$ 202

Income Taxes (Details) - Unreco

Income Taxes (Details) - Unrecognized Tax Benefits - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Reconciliation of unrecognized tax benefits [Roll Forward]
Unrecognized tax benefits, balance at January 1	$ 31	$ 6
Additions for tax positions of prior years	8	25
Reductions for tax positions of prior years	0	0
Reductions based on tax positions related to current year	0	0
Expiration of statute of limitations	(2)	0
Unrecognized tax benefits, balance at December 31	37	31	$ 6
Unrecognized tax benefits that, if recognized, would affect the annual effective tax rate	34	29
Amount of unrecognized tax benefits that are tax positions for which the ultimate deductibility is certain, but for which there is uncertainty about the timing of deductibility	3	2
Amount of interest benefit recognized on unrecognized tax benefits in income taxes	(1)	(10)	$ (33)
Accrued payment of interest balance for unrecognized tax benefits	$ 13	$ 14

Share-Based Incentive Compens_3

Share-Based Incentive Compensation Share-based Incentive Compensation (Details) - USD ($) $ / shares in Units, $ in Millions	Feb. 04, 2020	May 31, 2019	May 31, 2017	May 31, 2016	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Summary of stock option activity [Roll Forward]
Stock options outstanding, beginning of year, number (in shares)					8,994,356
Stock options granted, number (in shares)					2,057,494
Stock options exercised, number (in shares)					(1,874,412)
Stock options forfeited or expired, number (in shares)					(114,164)
Stock options outstanding, end of year, number (in shares)					9,063,274	8,994,356
Stock options outstanding, beginning of year, weighted average exercise price (in dollars per share)					$ 106.93
Stock options granted, weighted average exercise price (in dollars per share)					126.19
Stock options exercised, weighted average exercise price (in dollars per share)					92.98
Stock options forfeited or expired, weighted average exercise price (in dollars per share)					127.55
Stock options outstanding, end of year, weighted average exercise price (in dollars per share)					$ 113.93	$ 106.93
Stock options outstanding, weighted average contractual life remaining (in years)					6 years 3 months 18 days
Stock options outstanding, aggregate intrinsic value					$ 215
Stock options vested at end of year, number (in shares)					6,025,208
Stock options vested at end of year, weighted average exercise price (in dollars per share)					$ 106.91
Stock options vested at end of year, weighted average contractual life remaining (in years)					5 years 3 months 18 days
Stock options vested at end of year, aggregate intrinsic value					$ 184
Stock options exercisable at end of year, number (in shares)					4,001,010
Stock options exercisable at end of year, weighted average exercise price (in dollars per share)					$ 96.37
Stock options exercisable at end of year, weighted average contractual life remaining (in years)					3 years 10 months 24 days
Stock options exercisable at end of year, aggregate intrinsic value					$ 163
Stock option grants [Member]
Assumptions used in estimating fair value of options
Expected term of stock options					6 years	6 years	6 years
Expected volatility of Company’s stock (percent)						14.94%	16.50%
Weighted average volatility (percent)					15.48%	14.94%	16.50%
Expected annual dividend per share (in dollars per share)						$ 2.88	$ 2.68
Risk-free rate						2.68%	2.08%
Stock options granted, weighted average grant-date fair value of options granted (in dollars per share)					$ 16.64	$ 20.13	$ 16.15
Total intrinsic value of options exercised during the year					$ 88	$ 67	$ 90
Stock option grants [Member] \| Minimum [Member]
Assumptions used in estimating fair value of options
Expected volatility of Company’s stock (percent)					15.47%
Expected annual dividend per share (in dollars per share)					$ 3.08
Risk-free rate					1.70%
Stock option grants [Member] \| Maximum [Member]
Assumptions used in estimating fair value of options
Expected volatility of Company’s stock (percent)					15.91%
Expected annual dividend per share (in dollars per share)					$ 3.28
Risk-free rate					2.54%
The Travelers Companies, Inc 2014 Stock Incentive Plan [Member]
Share-based compensation plan description
Number of shares of the Company's common stock originally authorized for grant under the 2014 Incentive Plan (in shares)					10,000,000
Additional number of shares of the Company's common stock authorized for grant under the 2014 Incentive plan (in shares)		3,100,000	2,500,000	4,400,000
Number of shares of the Company's common stock authorized for grant under the 2014 Incentive Plan, total (in shares)					20,000,000
The Travelers Companies, Inc 2014 Stock Incentive Plan [Member] \| Stock option grants [Member]
Share-based compensation plan description
Option term					10 years
Award vesting period					3 years
The Travelers Companies, Inc 2014 Stock Incentive Plan [Member] \| Stock option grants [Member] \| Subsequent event [Member]
Assumptions used in estimating fair value of options
Stock options granted, weighted average grant-date fair value of options granted (in dollars per share)	$ 14.41
Summary of stock option activity [Roll Forward]
Stock options granted, number (in shares)	2,474,036
Stock options granted, weighted average exercise price (in dollars per share)	$ 132.58
The Travelers Companies, Inc 2014 Stock Incentive Plan [Member] \| Director deferred stock awards [Member]
Share-based compensation plan description
Number of days prior to date of annual meeting in year following date of grant in which annual deferred stock awards vest in full					1 day
Number of months after termination of service as a director before distributions of deferred stock awards begin					6 months

Share-Based Incentive Compens_4

Share-Based Incentive Compensation Share-Based Incentive Compensation (Details) - Restricted Stock - USD ($) $ / shares in Units, $ in Millions	Feb. 04, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Restricted stock units, deferred stock units and performance share awards [Member]
Share-based compensation
Fair value of shares that vested during the year		$ 130	$ 135	$ 166
Restricted stock units, deferred stock units and performance share awards [Member] \| Subsequent event [Member]
Summary of other equity instruments [Roll Forward]
Other equity instruments, granted, number (in shares)	911,291
Other equity instruments, granted, weighted average grant-date fair value (in dollars per share)	$ 132.58
Restricted and deferred stock units [Member]
Summary of other equity instruments [Roll Forward]
Other equity instruments, nonvested, number, beginning of year (in shares)		1,216,676
Other equity instruments, granted, number (in shares)		591,365
Other equity instruments, vested, number (in shares)		(592,754)
Other equity instruments, forfeited, number (in shares)		(77,626)
Other equity instruments, nonvested, number, end of year (in shares)		1,137,661	1,216,676
Other equity instruments, nonvested, weighted average grant-date fair value, beginning of year (in dollars per share)		$ 122.34
Other equity instruments, granted, weighted average grant-date fair value (in dollars per share)		126.88
Other equity instruments, vested, weighted average grant-date fair value (in dollars per share)		114.17
Other equity instruments, forfeited, weighted average grant-date fair value (in dollars per share)		127.75
Other equity instruments, nonvested, weighted average grant-date fair value, end of year (in dollars per share)		$ 128.59	$ 122.34
Other equity instruments, nonvested dividend equivalents, number, beginning of year (in shares)		329
Other equity instruments, nonvested dividend equivalents, number, end of year (in shares)		285	329
Restricted and deferred stock units [Member] \| Subsequent event [Member]
Summary of other equity instruments [Roll Forward]
Other equity instruments, granted, number (in shares)	540,881
Restricted stock units [Member]
Share-based compensation
Award vesting period		3 years
Performance shares [Member]
Share-based compensation
Award vesting period		3 years
Performance period		3 years
Summary of other equity instruments [Roll Forward]
Other equity instruments, nonvested, number, beginning of year (in shares)		684,889
Other equity instruments, granted, number (in shares)		371,754
Other equity instruments, vested, number (in shares)		(365,743)
Other equity instruments, forfeited, number (in shares)		(27,625)
Other equity instruments, performance-based adjustment, number (in shares)		5,472
Other equity instruments, nonvested, number, end of year (in shares)		668,747	684,889
Other equity instruments, nonvested, weighted average grant-date fair value, beginning of year (in dollars per share)		$ 128.83
Other equity instruments, granted, weighted average grant-date fair value (in dollars per share)		126.18
Other equity instruments, vested, weighted average grant-date fair value (in dollars per share)		118.78
Other equity instruments, forfeited, weighted average grant-date fair value (in dollars per share)		129.78
Other equity instruments, performance-based adjustment, weighted average grant-date fair value (in dollars per share)		123.17
Other equity instruments, nonvested, weighted average grant-date fair value, end of year (in dollars per share)		$ 132.76	$ 128.83
Other equity instruments, nonvested dividend equivalents, number, beginning of year (in shares)		24,876
Other equity instruments, nonvested dividend equivalents, number, end of year (in shares)		22,359	24,876
Performance shares [Member] \| Subsequent event [Member]
Summary of other equity instruments [Roll Forward]
Other equity instruments, granted, number (in shares)	370,410
Performance shares [Member] \| February 2018, 2019 and 2020 Awards [Member] \| Minimum [Member]
Share-based compensation
Percentage of performance shares to vest		50.00%
Performance shares [Member] \| February 2018, 2019 and 2020 Awards [Member] \| Maximum [Member]
Share-based compensation
Percentage of performance shares to vest		150.00%
Restricted common stock [Member] \| Simply Business [Member]
Summary of other equity instruments [Roll Forward]
Other equity instruments, nonvested, number, beginning of year (in shares)			95,953
Other equity instruments, nonvested, number, end of year (in shares)		41,997		95,953

Share-Based Incentive Compensta

Share-Based Incentive Compenstaion (Details) - Cost Recognition - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based compensation
Total compensation cost recognized in earnings for all share-based incentive compensation awards	$ 142	$ 140	$ 136
Tax benefit recognized in earnings related to compensation costs	26	26	45
Total unrecognized compensation cost related to all nonvested share-based incentive compensation awards	$ 136
Weighted-average period of recognition for unrecognized compensation cost (in years)	1 year 8 months 12 days
Cash received from the exercise of employee stock options under share-based compensation plans	$ 213	132	173
Tax benefit for tax deductions from employee stock options exercised	$ 18	14	31
Minimum [Member]
Share-based compensation
Estimated annual forfeiture rate reflected in share-based compensation cost (percent)	3.50%
Maximum [Member]
Share-based compensation
Estimated annual forfeiture rate reflected in share-based compensation cost (percent)	4.50%
Performance shares [Member]
Share-based compensation
Estimated attainment of performance shares at grant date (percent)	100.00%
Compensation cost adjustments for the updated estimate of performance shares due to attaining certain performance levels	$ 2	$ 3	$ 3

Pension Plans, Retirement Ben_3

Pension Plans, Retirement Benefits and Savings Plans (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Pension Plans [Member]
Change in projected benefit obligation [Roll Forward]
Benefit obligation, balance, beginning of year	$ 3,659	$ 3,909
Benefits earned	118	133	$ 119
Interest cost on benefit obligation	141	126	127
Actuarial (gain) loss	470	(284)
Benefits paid	(198)	(219)
Foreign currency exchange rate change, change in projected benefit obligation	5	(6)
Benefit obligation, balance, end of year	4,195	3,659	3,909
Change in plan assets [Roll Forward]
Fair value of plan assets, balance, beginning of year	3,874	4,070
Actual return on plan assets	696	(180)
Company contributions	8	210
Benefits paid	(198)	(219)
Foreign currency exchange rate change, change in plan assets	5	(7)
Fair value of plan assets, balance, end of year	4,385	3,874	4,070
Funded status of plan at end of year	190	215
Amounts recognized in the consolidated balance sheet consist of:
Accrued over-funded benefit plan assets	317	331
Accrued under-funded benefit plan liabilities	(127)	(116)
Total amount recognized in the consolidated balance sheet	190	215
Amounts recognized in accumulated other comprehensive income consist of:
Net actuarial loss (gain)	1,143	1,149
Prior service cost (benefit)	(3)	(4)
Total amount recognized in accumulated other comprehensive income	1,140	1,145
Pension Plans [Member] \| United States [Member] \| Qualified Plan [Member]
Change in projected benefit obligation [Roll Forward]
Benefit obligation, balance, beginning of year	3,444	3,679
Benefits earned	112	126
Interest cost on benefit obligation	134	119
Actuarial (gain) loss	451	(273)
Benefits paid	(187)	(207)
Foreign currency exchange rate change, change in projected benefit obligation	0	0
Benefit obligation, balance, end of year	3,954	3,444	3,679
Change in plan assets [Roll Forward]
Fair value of plan assets, balance, beginning of year	3,771	3,957
Actual return on plan assets	686	(179)
Company contributions	0	200	300
Benefits paid	(187)	(207)
Foreign currency exchange rate change, change in plan assets	0	0
Fair value of plan assets, balance, end of year	4,270	3,771	3,957
Funded status of plan at end of year	316	327
Amounts recognized in the consolidated balance sheet consist of:
Accrued over-funded benefit plan assets	316	327
Accrued under-funded benefit plan liabilities	0	0
Total amount recognized in the consolidated balance sheet	316	327
Amounts recognized in accumulated other comprehensive income consist of:
Net actuarial loss (gain)	1,094	1,113
Prior service cost (benefit)	(3)	(5)
Total amount recognized in accumulated other comprehensive income	1,091	1,108
Nonqualified and Foreign Pension Plans [Member]
Change in projected benefit obligation [Roll Forward]
Benefit obligation, balance, beginning of year	215	230
Benefits earned	6	7
Interest cost on benefit obligation	7	7
Actuarial (gain) loss	19	(11)
Benefits paid	(11)	(12)
Foreign currency exchange rate change, change in projected benefit obligation	5	(6)
Benefit obligation, balance, end of year	241	215	230
Change in plan assets [Roll Forward]
Fair value of plan assets, balance, beginning of year	103	113
Actual return on plan assets	10	(1)
Company contributions	8	10
Benefits paid	(11)	(12)
Foreign currency exchange rate change, change in plan assets	5	(7)
Fair value of plan assets, balance, end of year	115	103	113
Funded status of plan at end of year	(126)	(112)
Amounts recognized in the consolidated balance sheet consist of:
Accrued over-funded benefit plan assets	1	4
Accrued under-funded benefit plan liabilities	(127)	(116)
Total amount recognized in the consolidated balance sheet	(126)	(112)
Amounts recognized in accumulated other comprehensive income consist of:
Net actuarial loss (gain)	49	36
Prior service cost (benefit)	0	1
Total amount recognized in accumulated other comprehensive income	49	37
Postretirement Benefit Plans [Member]
Change in projected benefit obligation [Roll Forward]
Benefit obligation, balance, beginning of year	203	225
Benefits earned	0	0	0
Interest cost on benefit obligation	7	7	7
Actuarial (gain) loss	(31)	(18)
Benefits paid	(9)	(10)
Foreign currency exchange rate change, change in projected benefit obligation	1	(1)
Benefit obligation, balance, end of year	171	203	225
Change in plan assets [Roll Forward]
Fair value of plan assets, balance, beginning of year	12	13
Actual return on plan assets	1	0
Company contributions	8	9
Benefits paid	(9)	(10)
Fair value of plan assets, balance, end of year	12	12	$ 13
Funded status of plan at end of year	(159)	(191)
Amounts recognized in the consolidated balance sheet consist of:
Accrued under-funded benefit plan liabilities	(159)	(191)
Total amount recognized in the consolidated balance sheet	(159)	(191)
Amounts recognized in accumulated other comprehensive income consist of:
Net actuarial loss (gain)	(49)	(17)
Prior service cost (benefit)	(21)	(25)
Total amount recognized in accumulated other comprehensive income	$ (70)	$ (42)

Pension Plans, Retirement Ben_4

Pension Plans, Retirement Benefits and Savings Plans (Details) - Additional Pension Disclosures - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Other changes in benefit plan assets and benefit obligations recognized in other comprehensive income:
Total other changes in benefit plan assets and benefit obligations recognized in other comprehensive income	$ (33)	$ 56	$ (29)
Pension Plans [Member]
Defined benefit plan disclosure
Total accumulated benefit obligation	4,050	3,530
Aggregate projected benefit obligation for plans with a projected benefit obligation in excess of plan assets	228	203
Aggregate plan assets for plans with a projected benefit obligation in excess of plan assets	100	87
Aggregate accumulated benefit obligation for plans with an accumulated benefit obligation in excess of plan assets	218	195
Aggregate plan assets for plans with an accumulated benefit obligation in excess of plan assets	100	87
Actuarial gain (loss)	(470)	284
Company contributions	8	210
Components of net periodic benefit cost
Service cost	118	133	119
Interest cost on benefit obligation	141	126	127
Expected return on plan assets	(275)	(264)	(240)
Net periodic benefit cost, settlement	0	0	3
Net periodic benefit cost, amortization of unrecognized prior service benefit	(1)	(1)	(1)
Net periodic benefit cost, amortization of unrecognized net actuarial loss	56	91	85
Total non-service cost (benefit)	(79)	(48)	(26)
Net periodic benefit cost	39	85	93
Other changes in benefit plan assets and benefit obligations recognized in other comprehensive income:
Other changes in benefit plan assets and benefit obligations recognized in other comprehensive income, prior service benefit	0	0	0
Other changes in benefit plan assets and benefit obligations recognized in other comprehensive income, net actuarial loss (gain)	49	160	40
Other changes in benefit plan assets and benefit obligations recognized in other comprehensive income, foreign currency exchange rate change	1	(1)	2
Other changes in benefit plan assets and benefit obligations recognized in other comprehensive income, settlement	0	0	(2)
Other changes in benefit plan assets and benefit obligations recognized in other comprehensive income, amortization of prior service benefit	1	1	1
Other changes in benefit plan assets and benefit obligations recognized in other comprehensive income, amortization of net actuarial loss	(56)	(91)	(85)
Total other changes in benefit plan assets and benefit obligations recognized in other comprehensive income	(5)	69	(44)
Total other changes recognized in net periodic benefit cost and other comprehensive income	34	154	49
Pension Plans [Member] \| Net investment income [Member]
Components of net periodic benefit cost
Service cost	1	1	0
Pension Plans [Member] \| Claims and claim adjustment expenses [Member]
Components of net periodic benefit cost
Service cost	48	54	48
Total non-service cost (benefit)	(33)	(19)	(11)
Pension Plans [Member] \| General and administrative expenses [Member]
Components of net periodic benefit cost
Service cost	69	78	71
Total non-service cost (benefit)	(46)	(29)	(15)
Pension Plans [Member] \| United States [Member] \| Qualified Plan [Member]
Defined benefit plan disclosure
Total accumulated benefit obligation	3,820	3,320
Actuarial gain (loss)	(451)	273
Required contributions made	0	0	0
Company contributions	0	200	300
Required contributions during next fiscal year	0
Components of net periodic benefit cost
Service cost	112	126
Interest cost on benefit obligation	134	119
Nonqualified and Foreign Pension Plans [Member]
Defined benefit plan disclosure
Total accumulated benefit obligation	230	210
Actuarial gain (loss)	(19)	11
Company contributions	8	10
Components of net periodic benefit cost
Service cost	6	7
Interest cost on benefit obligation	7	7
Postretirement Benefit Plans [Member]
Defined benefit plan disclosure
Aggregate accumulated benefit obligation for plans with an accumulated benefit obligation in excess of plan assets	171	203
Aggregate plan assets for plans with an accumulated benefit obligation in excess of plan assets	12	12
Actuarial gain (loss)	31	18
Company contributions	8	9
Components of net periodic benefit cost
Service cost	0	0	0
Interest cost on benefit obligation	7	7	7
Expected return on plan assets	(1)	0	0
Net periodic benefit cost, settlement	0	0	0
Net periodic benefit cost, amortization of unrecognized prior service benefit	(3)	(4)	(4)
Net periodic benefit cost, amortization of unrecognized net actuarial loss	0	0	0
Total non-service cost (benefit)	3	3	3
Net periodic benefit cost	3	3	3
Other changes in benefit plan assets and benefit obligations recognized in other comprehensive income:
Other changes in benefit plan assets and benefit obligations recognized in other comprehensive income, prior service benefit	0	0	0
Other changes in benefit plan assets and benefit obligations recognized in other comprehensive income, net actuarial loss (gain)	(31)	(18)	13
Other changes in benefit plan assets and benefit obligations recognized in other comprehensive income, foreign currency exchange rate change	0	0	(1)
Other changes in benefit plan assets and benefit obligations recognized in other comprehensive income, settlement	0	0	0
Other changes in benefit plan assets and benefit obligations recognized in other comprehensive income, amortization of prior service benefit	3	4	4
Other changes in benefit plan assets and benefit obligations recognized in other comprehensive income, amortization of net actuarial loss	0	0	0
Total other changes in benefit plan assets and benefit obligations recognized in other comprehensive income	(28)	(14)	16
Total other changes recognized in net periodic benefit cost and other comprehensive income	(25)	(11)	19
Postretirement Benefit Plans [Member] \| Net investment income [Member]
Components of net periodic benefit cost
Service cost	0	0	0
Postretirement Benefit Plans [Member] \| Claims and claim adjustment expenses [Member]
Components of net periodic benefit cost
Service cost	0	0	0
Total non-service cost (benefit)	1	1	1
Postretirement Benefit Plans [Member] \| General and administrative expenses [Member]
Components of net periodic benefit cost
Service cost	0	0	0
Total non-service cost (benefit)	$ 2	$ 2	$ 2

Pension Plans, Retirement Ben_5

Pension Plans, Retirement Benefits and Savings Plans (Details) - Assumptions - United States [Member]	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Pension Plans [Member]
Defined benefit plan disclosure
Assumptions used to determine benefit obligations, cash balance interest crediting rate (percent)	4.01%	4.01%
Assumptions used to determine benefit obligations, future compensation increase rate (percent)	4.00%	4.00%
Assumptions used to determine net periodic benefit cost, expected long-term rate of return on assets (percent)	7.00%	7.00%
Pension Plans [Member] \| Qualified Plan [Member]
Defined benefit plan disclosure
Assumptions used to determine benefit obligations, discount rate (percent)	3.28%	4.39%
Assumptions used to determine net periodic benefit cost, discount rate used to measure service cost (percent)	4.57%	3.87%
Assumptions used to determine net periodic benefit cost, discount rate used to measure interest cost (percent)	4.02%	3.34%
Pension Plans [Member] \| Nonqualified Plan [Member]
Defined benefit plan disclosure
Assumptions used to determine benefit obligations, discount rate (percent)	3.17%	4.33%
Assumptions used to determine net periodic benefit cost, discount rate used to measure service cost (percent)	4.40%	3.73%
Assumptions used to determine net periodic benefit cost, discount rate used to measure interest cost (percent)	3.95%	3.26%
Postretirement Benefit Plans [Member]
Defined benefit plan disclosure
Assumptions used to determine benefit obligations, discount rate (percent)	3.09%	4.26%
Assumptions used to determine net periodic benefit cost, discount rate used to measure interest cost (percent)	3.90%	3.21%
Assumptions used to determine net periodic benefit cost, expected long-term rate of return on assets (percent)	4.00%	4.00%
Assumed health care cost trend rates, rate to which the cost trend rate is assumed to decline (ultimate trend rate) (percent)	4.50%	4.50%
Postretirement Benefit Plan Before Age 65 [Member]
Defined benefit plan disclosure
Assumed health care cost trend rates, medical, following year (percent)	7.00%	7.50%
Assumed health care cost trend rates, medical, year that the rate reaches the ultimate trend rate	2026	2026
Postretirement Benefit Plan Age 65 and Older [Member]
Defined benefit plan disclosure
Assumed health care cost trend rates, medical, following year (percent)	8.25%	8.75%
Assumed health care cost trend rates, medical, year that the rate reaches the ultimate trend rate	2026	2026

Pension Plans, Retirement Ben_6

Pension Plans, Retirement Benefits and Savings Plans Pension Plans, Retirement Benefits and Savings Plans (Details) - Additional Information	Dec. 31, 2019
Pension Plans [Member] \| United States [Member] \| Qualified Plan [Member] \| Equity securities [Member] \| Minimum [Member]
Defined benefit plan disclosure
Investment in class of securities (as a percentage)	55.00%
Pension Plans [Member] \| United States [Member] \| Qualified Plan [Member] \| Equity securities [Member] \| Maximum [Member]
Defined benefit plan disclosure
Investment in class of securities (as a percentage)	65.00%
Pension Plans [Member] \| United States [Member] \| Qualified Plan [Member] \| Fixed income securities [Member] \| Minimum [Member]
Defined benefit plan disclosure
Investment in class of securities (as a percentage)	20.00%
Pension Plans [Member] \| United States [Member] \| Qualified Plan [Member] \| Fixed income securities [Member] \| Maximum [Member]
Defined benefit plan disclosure
Investment in class of securities (as a percentage)	40.00%
Pension Plans [Member] \| United States [Member] \| Qualified Plan [Member] \| Long-term growth [Member] \| Minimum [Member]
Defined benefit plan disclosure
Investment in class of securities (as a percentage)	85.00%
Pension Plans [Member] \| United States [Member] \| Qualified Plan [Member] \| Long-term growth [Member] \| Maximum [Member]
Defined benefit plan disclosure
Investment in class of securities (as a percentage)	90.00%
Pension Plans [Member] \| United States [Member] \| Qualified Plan [Member] \| Near-term benefit payments [Member] \| Minimum [Member]
Defined benefit plan disclosure
Investment in class of securities (as a percentage)	10.00%
Pension Plans [Member] \| United States [Member] \| Qualified Plan [Member] \| Near-term benefit payments [Member] \| Maximum [Member]
Defined benefit plan disclosure
Investment in class of securities (as a percentage)	15.00%
Postretirement Benefit Plans [Member] \| Fixed income securities [Member] \| Minimum [Member]
Defined benefit plan disclosure
Investment in class of securities (as a percentage)	25.00%
Postretirement Benefit Plans [Member] \| Fixed income securities [Member] \| Maximum [Member]
Defined benefit plan disclosure
Investment in class of securities (as a percentage)	75.00%
Postretirement Benefit Plans [Member] \| Long-term growth [Member] \| Minimum [Member]
Defined benefit plan disclosure
Investment in class of securities (as a percentage)	35.00%
Postretirement Benefit Plans [Member] \| Long-term growth [Member] \| Maximum [Member]
Defined benefit plan disclosure
Investment in class of securities (as a percentage)	65.00%
Postretirement Benefit Plans [Member] \| Near-term benefit payments [Member] \| Minimum [Member]
Defined benefit plan disclosure
Investment in class of securities (as a percentage)	35.00%
Postretirement Benefit Plans [Member] \| Near-term benefit payments [Member] \| Maximum [Member]
Defined benefit plan disclosure
Investment in class of securities (as a percentage)	65.00%

Pension Plans, Retirement Ben_7

Pension Plans, Retirement Benefits and Savings Plans (Details) - Fair Value - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Pension Plans [Member]
Defined benefit plan disclosure
Fair value of plan assets	$ 4,385	$ 3,874	$ 4,070
Pension Plans [Member] \| Level 1 [Member]
Defined benefit plan disclosure
Fair value of plan assets	3,525	2,871
Pension Plans [Member] \| Level 2 [Member]
Defined benefit plan disclosure
Fair value of plan assets	858	1,002
Pension Plans [Member] \| Level 3 [Member]
Defined benefit plan disclosure
Fair value of plan assets	2	1
Pension Plans [Member] \| Fixed maturities [Member]
Defined benefit plan disclosure
Fair value of plan assets	778	772
Pension Plans [Member] \| Fixed maturities [Member] \| Level 1 [Member]
Defined benefit plan disclosure
Fair value of plan assets	0	0
Pension Plans [Member] \| Fixed maturities [Member] \| Level 2 [Member]
Defined benefit plan disclosure
Fair value of plan assets	778	772
Pension Plans [Member] \| Fixed maturities [Member] \| Level 3 [Member]
Defined benefit plan disclosure
Fair value of plan assets	0	0
Pension Plans [Member] \| Obligations of states, municipalities and political subdivisions [Member]
Defined benefit plan disclosure
Fair value of plan assets	3	3
Pension Plans [Member] \| Obligations of states, municipalities and political subdivisions [Member] \| Level 1 [Member]
Defined benefit plan disclosure
Fair value of plan assets	0	0
Pension Plans [Member] \| Obligations of states, municipalities and political subdivisions [Member] \| Level 2 [Member]
Defined benefit plan disclosure
Fair value of plan assets	3	3
Pension Plans [Member] \| Obligations of states, municipalities and political subdivisions [Member] \| Level 3 [Member]
Defined benefit plan disclosure
Fair value of plan assets	0	0
Pension Plans [Member] \| Debt securities issued by foreign governments [Member]
Defined benefit plan disclosure
Fair value of plan assets	30	27
Pension Plans [Member] \| Debt securities issued by foreign governments [Member] \| Level 1 [Member]
Defined benefit plan disclosure
Fair value of plan assets	0	0
Pension Plans [Member] \| Debt securities issued by foreign governments [Member] \| Level 2 [Member]
Defined benefit plan disclosure
Fair value of plan assets	30	27
Pension Plans [Member] \| Debt securities issued by foreign governments [Member] \| Level 3 [Member]
Defined benefit plan disclosure
Fair value of plan assets	0	0
Pension Plans [Member] \| Mortgage-backed securities, collateralized mortgage obligations and pass-through securities [Member]
Defined benefit plan disclosure
Fair value of plan assets	30	30
Pension Plans [Member] \| Mortgage-backed securities, collateralized mortgage obligations and pass-through securities [Member] \| Level 1 [Member]
Defined benefit plan disclosure
Fair value of plan assets	0	0
Pension Plans [Member] \| Mortgage-backed securities, collateralized mortgage obligations and pass-through securities [Member] \| Level 2 [Member]
Defined benefit plan disclosure
Fair value of plan assets	30	30
Pension Plans [Member] \| Mortgage-backed securities, collateralized mortgage obligations and pass-through securities [Member] \| Level 3 [Member]
Defined benefit plan disclosure
Fair value of plan assets	0	0
Pension Plans [Member] \| All other corporate bonds [Member]
Defined benefit plan disclosure
Fair value of plan assets	715	712
Pension Plans [Member] \| All other corporate bonds [Member] \| Level 1 [Member]
Defined benefit plan disclosure
Fair value of plan assets	0	0
Pension Plans [Member] \| All other corporate bonds [Member] \| Level 2 [Member]
Defined benefit plan disclosure
Fair value of plan assets	715	712
Pension Plans [Member] \| All other corporate bonds [Member] \| Level 3 [Member]
Defined benefit plan disclosure
Fair value of plan assets	0	0
Pension Plans [Member] \| Total mutual funds [Member]
Defined benefit plan disclosure
Fair value of plan assets	2,454	2,048
Pension Plans [Member] \| Total mutual funds [Member] \| Level 1 [Member]
Defined benefit plan disclosure
Fair value of plan assets	2,444	2,039
Pension Plans [Member] \| Total mutual funds [Member] \| Level 2 [Member]
Defined benefit plan disclosure
Fair value of plan assets	10	9
Pension Plans [Member] \| Total mutual funds [Member] \| Level 3 [Member]
Defined benefit plan disclosure
Fair value of plan assets	0	0
Pension Plans [Member] \| Equity mutual funds [Member]
Defined benefit plan disclosure
Fair value of plan assets	1,585	1,288
Pension Plans [Member] \| Equity mutual funds [Member] \| Level 1 [Member]
Defined benefit plan disclosure
Fair value of plan assets	1,578	1,282
Pension Plans [Member] \| Equity mutual funds [Member] \| Level 2 [Member]
Defined benefit plan disclosure
Fair value of plan assets	7	6
Pension Plans [Member] \| Equity mutual funds [Member] \| Level 3 [Member]
Defined benefit plan disclosure
Fair value of plan assets	0	0
Pension Plans [Member] \| Bond mutual funds [Member]
Defined benefit plan disclosure
Fair value of plan assets	869	760
Pension Plans [Member] \| Bond mutual funds [Member] \| Level 1 [Member]
Defined benefit plan disclosure
Fair value of plan assets	866	757
Pension Plans [Member] \| Bond mutual funds [Member] \| Level 2 [Member]
Defined benefit plan disclosure
Fair value of plan assets	3	3
Pension Plans [Member] \| Bond mutual funds [Member] \| Level 3 [Member]
Defined benefit plan disclosure
Fair value of plan assets	0	0
Pension Plans [Member] \| Equity securities [Member]
Defined benefit plan disclosure
Fair value of plan assets	1,018	783
Pension Plans [Member] \| Equity securities [Member] \| Level 1 [Member]
Defined benefit plan disclosure
Fair value of plan assets	1,017	783
Pension Plans [Member] \| Equity securities [Member] \| Level 2 [Member]
Defined benefit plan disclosure
Fair value of plan assets	1	0
Pension Plans [Member] \| Equity securities [Member] \| Level 3 [Member]
Defined benefit plan disclosure
Fair value of plan assets	0	0
Pension Plans [Member] \| Other investments [Member]
Defined benefit plan disclosure
Fair value of plan assets	2	1
Pension Plans [Member] \| Other investments [Member] \| Level 1 [Member]
Defined benefit plan disclosure
Fair value of plan assets	0	0
Pension Plans [Member] \| Other investments [Member] \| Level 2 [Member]
Defined benefit plan disclosure
Fair value of plan assets	0	0
Pension Plans [Member] \| Other investments [Member] \| Level 3 [Member]
Defined benefit plan disclosure
Fair value of plan assets	2	1
Pension Plans [Member] \| Cash and short-term securities [Member]
Defined benefit plan disclosure
Fair value of plan assets	133	270
Pension Plans [Member] \| Cash and short-term securities [Member] \| Level 1 [Member]
Defined benefit plan disclosure
Fair value of plan assets	64	49
Pension Plans [Member] \| Cash and short-term securities [Member] \| Level 2 [Member]
Defined benefit plan disclosure
Fair value of plan assets	69	221
Pension Plans [Member] \| Cash and short-term securities [Member] \| Level 3 [Member]
Defined benefit plan disclosure
Fair value of plan assets	0	0
Pension Plans [Member] \| Cash and short-term securities, U.S. Treasury securities [Member]
Defined benefit plan disclosure
Fair value of plan assets	20	30
Pension Plans [Member] \| Cash and short-term securities, U.S. Treasury securities [Member] \| Level 1 [Member]
Defined benefit plan disclosure
Fair value of plan assets	20	30
Pension Plans [Member] \| Cash and short-term securities, U.S. Treasury securities [Member] \| Level 2 [Member]
Defined benefit plan disclosure
Fair value of plan assets	0	0
Pension Plans [Member] \| Cash and short-term securities, U.S. Treasury securities [Member] \| Level 3 [Member]
Defined benefit plan disclosure
Fair value of plan assets	0	0
Pension Plans [Member] \| Money market mutual funds [Member]
Defined benefit plan disclosure
Fair value of plan assets	27	0
Pension Plans [Member] \| Money market mutual funds [Member] \| Level 1 [Member]
Defined benefit plan disclosure
Fair value of plan assets	27	0
Pension Plans [Member] \| Money market mutual funds [Member] \| Level 2 [Member]
Defined benefit plan disclosure
Fair value of plan assets	0	0
Pension Plans [Member] \| Money market mutual funds [Member] \| Level 3 [Member]
Defined benefit plan disclosure
Fair value of plan assets	0	0
Pension Plans [Member] \| Cash and short-term securities, other [Member]
Defined benefit plan disclosure
Fair value of plan assets	86	240
Pension Plans [Member] \| Cash and short-term securities, other [Member] \| Level 1 [Member]
Defined benefit plan disclosure
Fair value of plan assets	17	19
Pension Plans [Member] \| Cash and short-term securities, other [Member] \| Level 2 [Member]
Defined benefit plan disclosure
Fair value of plan assets	69	221
Pension Plans [Member] \| Cash and short-term securities, other [Member] \| Level 3 [Member]
Defined benefit plan disclosure
Fair value of plan assets	0	0
Postretirement Benefit Plans [Member]
Defined benefit plan disclosure
Fair value of plan assets	12	12	$ 13
Postretirement Benefit Plans [Member] \| Level 2 [Member]
Defined benefit plan disclosure
Fair value of plan assets	$ 12	$ 12

Pension Plans, Retirement Ben_8

Pension Plans, Retirement Benefits and Savings Plans (Details) - Future Payments $ in Millions	Dec. 31, 2019USD ($)
Pension Plans [Member]
Estimated Future Benefit Payments
Benefits expected to be paid, 2020	$ 250
Benefits expected to be paid, 2021	261
Benefits expected to be paid, 2022	265
Benefits expected to be paid, 2023	273
Benefits expected to be paid, 2024	276
Benefits expected to be paid, 2025 through 2029	1,400
Postretirement Benefit Plans [Member]
Estimated Future Benefit Payments
Benefits expected to be paid, 2020	12
Benefits expected to be paid, 2021	12
Benefits expected to be paid, 2022	12
Benefits expected to be paid, 2023	12
Benefits expected to be paid, 2024	12
Benefits expected to be paid, 2025 through 2029	$ 55

Pension Plans, Retirement Ben_9

Pension Plans, Retirement Benefits and Savings Plans (Details) - Savings Plan - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Savings Plan
Expense related to all savings plans	$ 123,000,000	$ 118,000,000	$ 119,000,000
The Travelers 401(k) Savings Plan [Member]
Savings Plan
Maximum annual match	$ 6,500
Vesting percentage of employer match after vesting period	100.00%
Vesting period	3 years
The Travelers 401(k) Savings Plan [Member] \| Maximum [Member]
Savings Plan
Matching contribution as a percent of eligible pay	5.00%

Leases (Details)

Leases (Details) $ in Millions	12 Months Ended
Leases (Details) $ in Millions	Dec. 31, 2019USD ($)
Leases [Abstract]
Operating leases	$ 92
Short-term leases	10
Lease expense	102
Less: sublease income	0
Net lease cost	102
Cash payments to settle a lease liability reported in cash flows	104
Right-of-use assets obtained in exchange for new lease liabilities	$ 60
Weighted average discount rate (percent)	3.02%
Weighted average remaining lease term (in years)	5 years 1 month 6 days

Leases (Details) - Contractual

Leases (Details) - Contractual Maturities - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2019
Leases [Abstract]
Lease expense for real estate and other operating leases	$ 185	$ 188
Lease payments due, 2020			$ 108
Lease payments due, 2021			93
Lease payments due, 2022			71
Lease payments due, 2023			51
Lease payments due, 2024			35
Lease payments due, thereafter			54
Total undiscounted lease payments			412
Less: present value adjustment			32
Operating lease liability			$ 380

Contingencies, Commitments an_2

Contingencies, Commitments and Guarantees (Details) - Commitments - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Contingencies, Commitments and Guarantees [Abstract]
Unfunded commitments to private equity limited partnerships and real estate partnerships	$ 1,660	$ 1,600

Contingencies, Commitments an_3

Contingencies, Commitments and Guarantees (Details) - Guarantees $ in Millions	Dec. 31, 2019USD ($)
Indemnifications related to the sale of businesses [Member]
Guarantor obligations
Maximum amount of contingent obligation	$ 351
Guarantees of certain insurance policy obligations [Member]
Guarantor obligations
Maximum amount of contingent obligation	480
Amount indemnified by a third party	$ 480

Consolidating Financial State_3

Consolidating Financial Statements (Details) - Additional Information $ in Millions	Dec. 31, 2019USD ($)
Consolidating Financial Statements of The Travelers Companies, Inc. and Subsidiaries (Unaudited) disclosure
Amount of certain debt obligations of Travelers Property Casualty Corp. (TPC) and Travelers Insurance Group Holdings, Inc. (TIGHI) that are fully and unconditionally guaranteed by The Travelers Companies, Inc.	$ 700

Consolidating Financial State_4

Consolidating Financial Statements (Details) - Consolidating Statement of Income (Unaudited) - USD ($) $ in Millions		3 Months Ended								12 Months Ended
		Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Consolidating Statement of Income
Premiums										$ 28,272	$ 27,059	$ 25,683
Net investment income										2,468	2,474	2,397
Fee income										459	432	447
Net realized investment gains (losses)	[1]									113	114	216
Other revenues										269	203	159
Total revenues		$ 8,063	$ 8,013	$ 7,834	$ 7,671	$ 7,796	$ 7,723	$ 7,477	$ 7,286	31,581	30,282	28,902
Claims and claim adjustment expenses										19,133	18,291	17,467
Amortization of deferred acquisition costs										4,601	4,381	4,166
General and administrative expenses										4,365	4,297	4,170
Interest expense										344	352	369
Total claims and expenses		6,989	7,581	7,169	6,704	7,050	6,917	6,846	6,508	28,443	27,321	26,172
Income before income taxes		1,074	432	665	967	746	806	631	778	3,138	2,961	2,730
Income tax expense (benefit)		201	36	108	171	125	97	107	109	516	438	674
Net income of subsidiaries										0	0	0
Net income		$ 873	$ 396	$ 557	$ 796	$ 621	$ 709	$ 524	$ 669	2,622	2,523	2,056
Total other-than-temporary impairment losses										(3)	(1)	(13)
Other-than-temporary impairment losses recognized in net realized investment gains (losses)										(4)	(1)
Other-than-temporary impairment losses recognized in net realized investment gains (losses)												(14)
Other-than-temporary impairment losses recognized in other comprehensive income (loss)											0
Other-than-temporary impairment gains recognized in other comprehensive income (loss)										1		1
TRV [Member]
Consolidating Statement of Income
Net investment income										41	32	24
Net realized investment gains (losses)										33	(13)	66
Total revenues										74	19	90
General and administrative expenses										21	20	25
Interest expense										297	304	321
Total claims and expenses										318	324	346
Income before income taxes										(244)	(305)	(256)
Income tax expense (benefit)										(77)	(114)	(130)
Net income of subsidiaries										2,789	2,714	2,190
Net income										2,622	2,523	2,064
Other-than-temporary impairment losses recognized in net realized investment gains (losses)										0	0
Other-than-temporary impairment losses recognized in net realized investment gains (losses)												0
Other-than-temporary impairment losses recognized in other comprehensive income (loss)											0
Other-than-temporary impairment gains recognized in other comprehensive income (loss)										0		0
Reportable Legal Entities [Member] \| TPC [Member]
Consolidating Statement of Income
Premiums										19,362	18,508	17,562
Net investment income										1,730	1,704	1,627
Fee income										458	432	447
Net realized investment gains (losses)										44	118	19
Other revenues										142	96	101
Total revenues										21,736	20,858	19,756
Claims and claim adjustment expenses										12,926	12,344	11,735
Amortization of deferred acquisition costs										3,095	2,972	2,820
General and administrative expenses										2,973	2,947	2,906
Interest expense										47	48	48
Total claims and expenses										19,041	18,311	17,509
Income before income taxes										2,695	2,547	2,247
Income tax expense (benefit)										483	437	519
Net income of subsidiaries										0	0	0
Net income										2,212	2,110	1,728
Total other-than-temporary impairment losses										(2)	(1)	(4)
Other-than-temporary impairment losses recognized in net realized investment gains (losses)										(2)	(1)
Other-than-temporary impairment losses recognized in net realized investment gains (losses)												(5)
Other-than-temporary impairment losses recognized in other comprehensive income (loss)											0
Other-than-temporary impairment gains recognized in other comprehensive income (loss)										0		1
Reportable Legal Entities [Member] \| Other Subsidiaries [Member]
Consolidating Statement of Income
Premiums										8,910	8,551	8,121
Net investment income										697	738	759
Fee income										1	0	0
Net realized investment gains (losses)										36	9	131
Other revenues										127	112	68
Total revenues										9,771	9,410	9,079
Claims and claim adjustment expenses										6,207	5,947	5,732
Amortization of deferred acquisition costs										1,506	1,409	1,346
General and administrative expenses										1,371	1,335	1,249
Interest expense										0	0	0
Total claims and expenses										9,084	8,691	8,327
Income before income taxes										687	719	752
Income tax expense (benefit)										110	115	290
Net income of subsidiaries										0	0	0
Net income										577	604	462
Total other-than-temporary impairment losses										(1)	0	(9)
Other-than-temporary impairment losses recognized in net realized investment gains (losses)										(2)	0
Other-than-temporary impairment losses recognized in net realized investment gains (losses)												(9)
Other-than-temporary impairment losses recognized in other comprehensive income (loss)											0
Other-than-temporary impairment gains recognized in other comprehensive income (loss)										1		0
Reportable Legal Entities [Member] \| TRV [Member]
Consolidating Statement of Income
Premiums										0	0	0
Net investment income										41	32	24
Fee income										0	0	0
Net realized investment gains (losses)										33	(13)	66
Other revenues										0	0	0
Total revenues										74	19	90
Claims and claim adjustment expenses										0	0	0
Amortization of deferred acquisition costs										0	0	0
General and administrative expenses										21	20	25
Interest expense										297	304	321
Total claims and expenses										318	324	346
Income before income taxes										(244)	(305)	(256)
Income tax expense (benefit)										(77)	(114)	(130)
Net income of subsidiaries										2,789	2,714	2,190
Net income										2,622	2,523	2,064
Total other-than-temporary impairment losses										0	0	0
Other-than-temporary impairment losses recognized in net realized investment gains (losses)										0	0
Other-than-temporary impairment losses recognized in net realized investment gains (losses)												0
Other-than-temporary impairment losses recognized in other comprehensive income (loss)											0
Other-than-temporary impairment gains recognized in other comprehensive income (loss)										0		0
Eliminations [Member]
Consolidating Statement of Income
Premiums										0	0	0
Net investment income										0	0	(13)
Fee income										0	0	0
Net realized investment gains (losses)										0	0	0
Other revenues										0	(5)	(10)
Total revenues										0	(5)	(23)
Claims and claim adjustment expenses										0	0	0
Amortization of deferred acquisition costs										0	0	0
General and administrative expenses										0	(5)	(10)
Interest expense										0	0	0
Total claims and expenses										0	(5)	(10)
Income before income taxes										0	0	(13)
Income tax expense (benefit)										0	0	(5)
Net income of subsidiaries										(2,789)	(2,714)	(2,190)
Net income										(2,789)	(2,714)	(2,198)
Total other-than-temporary impairment losses										0	0	0
Other-than-temporary impairment losses recognized in net realized investment gains (losses)										0	0
Other-than-temporary impairment losses recognized in net realized investment gains (losses)												0
Other-than-temporary impairment losses recognized in other comprehensive income (loss)											$ 0
Other-than-temporary impairment gains recognized in other comprehensive income (loss)										$ 0		$ 0

[1]	Total other-than-temporary impairment (OTTI) losses were $(3) million , $(1) million and $(13) million for the years ended December 31, 2019 , 2018 and 2017 , respectively. Of total OTTI, credit losses of $(4) million , $(1) million and $(14) million for the years ended December 31, 2019 , 2018 and 2017 , respectively, were recognized in net realized investment gains. In addition, unrealized gains (losses) from other changes in total OTTI of $1 million , $0 million and $1 million for the years ended December 31, 2019 , 2018 and 2017 , respectively, were recognized in other comprehensive income (loss) as part of changes in net unrealized gains (losses) on investment securities having credit losses recognized in the consolidated statement of income.

Consolidating Financial State_5

Consolidating Financial Statements (Details) - Consolidating Statement of Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Consolidating Statement of Comprehensive Income
Net income	$ 873	$ 396	$ 557	$ 796	$ 621	$ 709	$ 524	$ 669	$ 2,622	$ 2,523	$ 2,056
Changes in net unrealized gains on investment securities having no credit losses recognized in the consolidated statement of income									2,994	(1,489)	294
Changes in net unrealized gains on investment securities having credit losses recognized in the consolidated statement of income									(4)	(27)	8
Net changes in benefit plan assets and obligations									33	(56)	29
Net changes in unrealized foreign currency translation									117	(247)	191
Other comprehensive income (loss) before income taxes									3,140	(1,819)	522
Income tax expense (benefit)									641	(349)	110
Other comprehensive income (loss), net of taxes, before other comprehensive income (loss) of subsidiaries									2,499	(1,470)	412
Other comprehensive income (loss) of subsidiaries									0	0	0
Other comprehensive income (loss), net of taxes									2,499	(1,470)	412
Comprehensive income									5,121	1,053	2,468
TRV [Member]
Consolidating Statement of Comprehensive Income
Net income									2,622	2,523	2,064
Changes in net unrealized gains on investment securities having no credit losses recognized in the consolidated statement of income									4	0	(44)
Net changes in benefit plan assets and obligations									35	(53)	22
Other comprehensive income (loss) before income taxes									39	(53)	(22)
Income tax expense (benefit)									12	(17)	2
Other comprehensive income (loss), net of taxes, before other comprehensive income (loss) of subsidiaries									27	(36)	(24)
Other comprehensive income (loss) of subsidiaries									2,472	(1,434)	436
Other comprehensive income (loss), net of taxes									2,499	(1,470)	412
Comprehensive income									5,121	1,053	2,476
Reportable Legal Entities [Member] \| TPC [Member]
Consolidating Statement of Comprehensive Income
Net income									2,212	2,110	1,728
Changes in net unrealized gains on investment securities having no credit losses recognized in the consolidated statement of income									2,097	(1,028)	313
Changes in net unrealized gains on investment securities having credit losses recognized in the consolidated statement of income									(2)	(20)	6
Net changes in benefit plan assets and obligations									1	1	(1)
Net changes in unrealized foreign currency translation									53	(144)	83
Other comprehensive income (loss) before income taxes									2,149	(1,191)	401
Income tax expense (benefit)									441	(231)	98
Other comprehensive income (loss), net of taxes, before other comprehensive income (loss) of subsidiaries									1,708	(960)	303
Other comprehensive income (loss) of subsidiaries									0	0	0
Other comprehensive income (loss), net of taxes									1,708	(960)	303
Comprehensive income									3,920	1,150	2,031
Reportable Legal Entities [Member] \| Other Subsidiaries [Member]
Consolidating Statement of Comprehensive Income
Net income									577	604	462
Changes in net unrealized gains on investment securities having no credit losses recognized in the consolidated statement of income									893	(461)	25
Changes in net unrealized gains on investment securities having credit losses recognized in the consolidated statement of income									(2)	(7)	2
Net changes in benefit plan assets and obligations									(3)	(4)	8
Net changes in unrealized foreign currency translation									64	(103)	108
Other comprehensive income (loss) before income taxes									952	(575)	143
Income tax expense (benefit)									188	(101)	10
Other comprehensive income (loss), net of taxes, before other comprehensive income (loss) of subsidiaries									764	(474)	133
Other comprehensive income (loss) of subsidiaries									0	0	0
Other comprehensive income (loss), net of taxes									764	(474)	133
Comprehensive income									1,341	130	595
Reportable Legal Entities [Member] \| TRV [Member]
Consolidating Statement of Comprehensive Income
Net income									2,622	2,523	2,064
Changes in net unrealized gains on investment securities having no credit losses recognized in the consolidated statement of income									4	0	(44)
Changes in net unrealized gains on investment securities having credit losses recognized in the consolidated statement of income									0	0	0
Net changes in benefit plan assets and obligations									35	(53)	22
Net changes in unrealized foreign currency translation									0	0	0
Other comprehensive income (loss) before income taxes									39	(53)	(22)
Income tax expense (benefit)									12	(17)	2
Other comprehensive income (loss), net of taxes, before other comprehensive income (loss) of subsidiaries									27	(36)	(24)
Other comprehensive income (loss) of subsidiaries									2,472	(1,434)	436
Other comprehensive income (loss), net of taxes									2,499	(1,470)	412
Comprehensive income									5,121	1,053	2,476
Eliminations [Member]
Consolidating Statement of Comprehensive Income
Net income									(2,789)	(2,714)	(2,198)
Changes in net unrealized gains on investment securities having no credit losses recognized in the consolidated statement of income									0	0	0
Changes in net unrealized gains on investment securities having credit losses recognized in the consolidated statement of income									0	0	0
Net changes in benefit plan assets and obligations									0	0	0
Net changes in unrealized foreign currency translation									0	0	0
Other comprehensive income (loss) before income taxes									0	0	0
Income tax expense (benefit)									0	0	0
Other comprehensive income (loss), net of taxes, before other comprehensive income (loss) of subsidiaries									0	0	0
Other comprehensive income (loss) of subsidiaries									(2,472)	1,434	(436)
Other comprehensive income (loss), net of taxes									(2,472)	1,434	(436)
Comprehensive income									$ (5,261)	$ (1,280)	$ (2,634)

Consolidating Financial State_6

Consolidating Financial Statements (Details) - Consolidating Balance Sheet (Unaudited) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Consolidating Balance Sheet
Fixed maturities, at fair value	$ 68,134	$ 63,464
Equity securities, at fair value	425	368
Real estate investments	963	904
Short-term securities	4,943	3,985
Other investments	3,419	3,557
Total investments	77,884	72,278
Cash	494	373
Investment income accrued	618	624
Premiums receivable	7,909	7,506
Reinsurance recoverables	8,235	8,370
Ceded unearned premiums	689	578
Deferred acquisition costs	2,273	2,120
Deferred taxes	0	445
Contractholder receivables	4,619	4,785
Goodwill	3,961	3,937
Other intangible assets	330	345
Investment in subsidiaries	0	0
Other assets	3,110	2,872
Total assets	110,122	104,233
Claims and claim adjustment expense reserves	51,849	50,668
Unearned premium reserves	14,604	13,555
Contractholder payables	4,619	4,785
Payables for reinsurance premiums	363	289
Deferred taxes	137	0
Debt	6,558	6,564
Other liabilities	6,049	5,478
Total liabilities	84,179	81,339
Common stock	23,469	23,144
Additional paid-in capital	0	0
Retained earnings	36,977	35,204
Accumulated other comprehensive income (loss)	640	(1,859)
Treasury stock, at cost	(35,143)	(33,595)
Total shareholders’ equity	25,943	22,894	$ 23,731
Total liabilities and shareholders’ equity	110,122	104,233
Fixed maturities, available for sale, amortized cost	65,281	63,601
Equity securities, cost	$ 376	$ 382
Common stock, shares authorized (in shares)	1,750,000,000	1,750,000,000
Common stock, shares issued (in shares)	255,500,000	263,700,000
Common stock, shares outstanding (in shares)	255,500,000	263,600,000
Treasury stock, at cost, shares (in shares)	522,100,000	510,900,000
TRV [Member]
Consolidating Balance Sheet
Fixed maturities, at fair value	$ 91	$ 84
Equity securities, at fair value	209	171
Short-term securities	1,390	1,371
Investment in subsidiaries	30,028	26,993
Total assets	32,054	29,268
Debt	5,865	5,871
Total liabilities	6,104	6,367
Common stock	23,469	23,144
Retained earnings	36,984	35,211
Accumulated other comprehensive income (loss)	640	(1,859)
Treasury stock, at cost	(35,143)	(33,595)
Total shareholders’ equity	25,950	22,901
Total liabilities and shareholders’ equity	$ 32,054	$ 29,268
Common stock, shares authorized (in shares)	1,750,000,000	1,750,000,000
Common stock, shares issued (in shares)	255,500,000	263,700,000
Common stock, shares outstanding (in shares)	255,500,000	263,600,000
Treasury stock, at cost, shares (in shares)	522,100,000	510,900,000
Reportable Legal Entities [Member] \| TPC [Member]
Consolidating Balance Sheet
Fixed maturities, at fair value	$ 46,805	$ 43,683
Equity securities, at fair value	102	105
Real estate investments	1	2
Short-term securities	2,793	1,855
Other investments	2,690	2,746
Total investments	52,391	48,391
Cash	207	181
Investment income accrued	428	434
Premiums receivable	5,331	5,089
Reinsurance recoverables	6,511	5,904
Ceded unearned premiums	603	522
Deferred acquisition costs	2,094	1,930
Deferred taxes		167
Contractholder receivables	4,606	3,867
Goodwill	2,584	2,578
Other intangible assets	218	224
Investment in subsidiaries	0	0
Other assets	2,360	2,220
Total assets	77,333	71,507
Claims and claim adjustment expense reserves	35,568	34,093
Unearned premium reserves	10,144	9,414
Contractholder payables	4,606	3,867
Payables for reinsurance premiums	210	169
Deferred taxes	272
Debt	693	693
Other liabilities	4,609	4,133
Total liabilities	56,102	52,369
Common stock	0	0
Additional paid-in capital	11,634	11,634
Retained earnings	8,451	8,065
Accumulated other comprehensive income (loss)	1,146	(561)
Treasury stock, at cost	0	0
Total shareholders’ equity	21,231	19,138
Total liabilities and shareholders’ equity	77,333	71,507
Reportable Legal Entities [Member] \| Other Subsidiaries [Member]
Consolidating Balance Sheet
Fixed maturities, at fair value	21,238	19,697
Equity securities, at fair value	114	92
Real estate investments	962	902
Short-term securities	760	759
Other investments	728	810
Total investments	23,802	22,260
Cash	287	192
Investment income accrued	186	187
Premiums receivable	2,578	2,417
Reinsurance recoverables	1,724	2,466
Ceded unearned premiums	86	56
Deferred acquisition costs	179	190
Deferred taxes		302
Contractholder receivables	13	918
Goodwill	1,386	1,368
Other intangible assets	112	121
Investment in subsidiaries	0	0
Other assets	419	15
Total assets	30,772	30,492
Claims and claim adjustment expense reserves	16,281	16,575
Unearned premium reserves	4,460	4,141
Contractholder payables	13	918
Payables for reinsurance premiums	153	120
Deferred taxes	(170)
Debt	0	32
Other liabilities	1,236	849
Total liabilities	21,973	22,635
Common stock	585	401
Additional paid-in capital	7,073	7,023
Retained earnings	823	879
Accumulated other comprehensive income (loss)	318	(446)
Treasury stock, at cost	0	0
Total shareholders’ equity	8,799	7,857
Total liabilities and shareholders’ equity	30,772	30,492
Reportable Legal Entities [Member] \| TRV [Member]
Consolidating Balance Sheet
Fixed maturities, at fair value	91	84
Equity securities, at fair value	209	171
Real estate investments	0	0
Short-term securities	1,390	1,371
Other investments	1	1
Total investments	1,691	1,627
Cash	0	0
Investment income accrued	4	3
Premiums receivable	0	0
Reinsurance recoverables	0	0
Ceded unearned premiums	0	0
Deferred acquisition costs	0	0
Deferred taxes		(24)
Contractholder receivables	0	0
Goodwill	0	0
Other intangible assets	0	0
Investment in subsidiaries	30,028	26,993
Other assets	331	669
Total assets	32,054	29,268
Claims and claim adjustment expense reserves	0	0
Unearned premium reserves	0	0
Contractholder payables	0	0
Payables for reinsurance premiums	0	0
Deferred taxes	35
Debt	5,865	5,871
Other liabilities	204	496
Total liabilities	6,104	6,367
Common stock	23,469	23,144
Additional paid-in capital	0	0
Retained earnings	36,984	35,211
Accumulated other comprehensive income (loss)	640	(1,859)
Treasury stock, at cost	(35,143)	(33,595)
Total shareholders’ equity	25,950	22,901
Total liabilities and shareholders’ equity	32,054	29,268
Eliminations [Member]
Consolidating Balance Sheet
Fixed maturities, at fair value	0	0
Equity securities, at fair value	0	0
Real estate investments	0	0
Short-term securities	0	0
Other investments	0	0
Total investments	0	0
Cash	0	0
Investment income accrued	0	0
Premiums receivable	0	0
Reinsurance recoverables	0	0
Ceded unearned premiums	0	0
Deferred acquisition costs	0	0
Deferred taxes		0
Contractholder receivables	0	0
Goodwill	(9)	(9)
Other intangible assets	0	0
Investment in subsidiaries	(30,028)	(26,993)
Other assets	0	(32)
Total assets	(30,037)	(27,034)
Claims and claim adjustment expense reserves	0	0
Unearned premium reserves	0	0
Contractholder payables	0	0
Payables for reinsurance premiums	0	0
Deferred taxes	0
Debt	0	(32)
Other liabilities	0	0
Total liabilities	0	(32)
Common stock	(585)	(401)
Additional paid-in capital	(18,707)	(18,657)
Retained earnings	(9,281)	(8,951)
Accumulated other comprehensive income (loss)	(1,464)	1,007
Treasury stock, at cost	0	0
Total shareholders’ equity	(30,037)	(27,002)
Total liabilities and shareholders’ equity	$ (30,037)	$ (27,034)

Consolidating Financial State_7

Consolidating Financial Statements (Details) - Consolidating Statement of Cash Flows (Unaudited) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Consolidating Statement of Cash Flows
Net income	$ 873	$ 396	$ 557	$ 796	$ 621	$ 709	$ 524	$ 669	$ 2,622	$ 2,523	$ 2,056
Net adjustments to reconcile net income to net cash provided by operating activities									2,583	1,857	2,092
Net cash provided by operating activities									5,205	4,380	4,148
Proceeds from maturities of fixed maturities									6,845	7,086	8,750
Proceeds from sales of investments:
Fixed maturities									2,187	3,546	1,854
Equity securities									140	178
Equity securities											765
Real estate investments									0	74	23
Other investments									459	511	468
Purchases of investments:
Fixed maturities									(10,711)	(13,526)	(12,250)
Equity securities									(94)	(117)
Equity securities											(459)
Real estate investments									(107)	(74)	(59)
Other investments									(497)	(537)	(541)
Net sales (purchases) of short-term securities									(957)	908	(26)
Securities transactions in course of settlement									158	(56)	(47)
Acquisition, net of cash acquired									0	(4)	(439)
Other investing activities									(325)	(318)	(241)
Net cash used in investing activities									(2,902)	(2,329)	(2,202)
Treasury stock acquired — share repurchase authorization									(1,500)	(1,270)	(1,378)
Treasury stock acquired — net employee share-based compensation									(48)	(51)	(62)
Dividends paid to shareholders									(844)	(814)	(785)
Payment of debt									(500)	(600)	(657)
Issuance of debt									492	591	789
Issuance of common stock -- employee share options									213	132	173
Dividends paid to parent company									0	0	0
Net cash used in financing activities									(2,187)	(2,012)	(1,920)
Effect of exchange rate changes on cash									5	(10)	11
Net increase in cash									121	29	37
Cash at beginning of year				373				344	373	344	307
Cash at end of year	494				373				494	373	344
Income taxes paid (received)									428	408	514
Interest paid									338	347	367
TRV [Member]
Consolidating Statement of Cash Flows
Net income									2,622	2,523	2,064
Net cash provided by operating activities									2,214	2,160	2,032
Purchases of investments:
Net sales (purchases) of short-term securities									(19)	(141)	397
Acquisition, net of cash acquired									0	0	(477)
Net cash used in investing activities									(27)	(148)	(114)
Treasury stock acquired — share repurchase authorization									(1,500)	(1,270)	(1,378)
Treasury stock acquired — net employee share-based compensation									(48)	(51)	(62)
Dividends paid to shareholders									(844)	(814)	(785)
Payment of debt									(500)	(600)	(657)
Issuance of debt									492	591	789
Issuance of common stock -- employee share options									213	132	173
Net cash used in financing activities									(2,187)	(2,012)	(1,920)
Net increase in cash									0	0	(2)
Cash at beginning of year				0				0	0	0	2
Cash at end of year	0				0				0	0	0
Income taxes paid (received)									(78)	(283)	(173)
Interest paid									291	300	320
Reportable Legal Entities [Member] \| TPC [Member]
Consolidating Statement of Cash Flows
Net income									2,212	2,110	1,728
Net adjustments to reconcile net income to net cash provided by operating activities									1,750	1,141	1,500
Net cash provided by operating activities									3,962	3,251	3,228
Proceeds from maturities of fixed maturities									4,727	5,158	6,576
Proceeds from sales of investments:
Fixed maturities									1,295	2,449	1,007
Equity securities									53	65
Equity securities											97
Real estate investments										66	0
Other investments									345	403	357
Purchases of investments:
Fixed maturities									(7,011)	(9,404)	(8,513)
Equity securities									(2)	(8)
Equity securities											(68)
Real estate investments									0	(1)	(1)
Other investments									(424)	(454)	(444)
Net sales (purchases) of short-term securities									(939)	895	(303)
Securities transactions in course of settlement									163	(80)	(55)
Acquisition, net of cash acquired										0	0
Other investing activities									(317)	(310)	(244)
Net cash used in investing activities									(2,110)	(1,221)	(1,591)
Treasury stock acquired — share repurchase authorization									0	0	0
Treasury stock acquired — net employee share-based compensation									0	0	0
Dividends paid to shareholders									0	0	0
Payment of debt									0	0	0
Issuance of debt									0	0	0
Issuance of common stock -- employee share options									0	0	0
Dividends paid to parent company									(1,827)	(2,003)	(1,624)
Net cash used in financing activities									(1,827)	(2,003)	(1,624)
Effect of exchange rate changes on cash									1	(3)	3
Net increase in cash									26	24	16
Cash at beginning of year				181				157	181	157	141
Cash at end of year	207				181				207	181	157
Income taxes paid (received)									375	437	481
Interest paid									47	47	47
Reportable Legal Entities [Member] \| Other Subsidiaries [Member]
Consolidating Statement of Cash Flows
Net income									577	604	462
Net adjustments to reconcile net income to net cash provided by operating activities									943	605	701
Net cash provided by operating activities									1,520	1,209	1,163
Proceeds from maturities of fixed maturities									2,107	1,906	2,168
Proceeds from sales of investments:
Fixed maturities									891	1,096	846
Equity securities									75	107
Equity securities											414
Real estate investments										8	23
Other investments									114	108	124
Purchases of investments:
Fixed maturities									(3,686)	(4,096)	(3,697)
Equity securities									(75)	(99)
Equity securities											(133)
Real estate investments									(107)	(73)	(58)
Other investments									(73)	(83)	(97)
Net sales (purchases) of short-term securities									1	154	(120)
Securities transactions in course of settlement									(4)	24	5
Acquisition, net of cash acquired										(4)	25
Other investing activities									(8)	(8)	3
Net cash used in investing activities									(765)	(960)	(497)
Treasury stock acquired — share repurchase authorization									0	0	0
Treasury stock acquired — net employee share-based compensation									0	0	0
Dividends paid to shareholders									0	0	0
Payment of debt									(32)	0	0
Issuance of debt									0	18	14
Issuance of common stock -- employee share options									0	0	0
Dividends paid to parent company									(632)	(255)	(665)
Net cash used in financing activities									(664)	(237)	(651)
Effect of exchange rate changes on cash									4	(7)	8
Net increase in cash									95	5	23
Cash at beginning of year				192				187	192	187	164
Cash at end of year	287				192				287	192	187
Income taxes paid (received)									131	254	206
Interest paid									0	0	0
Reportable Legal Entities [Member] \| TRV [Member]
Consolidating Statement of Cash Flows
Net income									2,622	2,523	2,064
Net adjustments to reconcile net income to net cash provided by operating activities									(408)	(363)	(32)
Net cash provided by operating activities									2,214	2,160	2,032
Proceeds from maturities of fixed maturities									11	22	6
Proceeds from sales of investments:
Fixed maturities									1	1	1
Equity securities									12	6
Equity securities											254
Real estate investments										0	0
Other investments									0	0	0
Purchases of investments:
Fixed maturities									(14)	(26)	(40)
Equity securities									(17)	(10)
Equity securities											(258)
Real estate investments									0	0	0
Other investments									0	0	0
Net sales (purchases) of short-term securities									(19)	(141)	397
Securities transactions in course of settlement									(1)	0	3
Acquisition, net of cash acquired										0	(477)
Other investing activities									0	0	0
Net cash used in investing activities									(27)	(148)	(114)
Treasury stock acquired — share repurchase authorization									(1,500)	(1,270)	(1,378)
Treasury stock acquired — net employee share-based compensation									(48)	(51)	(62)
Dividends paid to shareholders									(844)	(814)	(785)
Payment of debt									(500)	(600)	(657)
Issuance of debt									492	591	789
Issuance of common stock -- employee share options									213	132	173
Dividends paid to parent company									0	0	0
Net cash used in financing activities									(2,187)	(2,012)	(1,920)
Effect of exchange rate changes on cash									0	0	0
Net increase in cash									0	0	(2)
Cash at beginning of year				0				0	0	0	2
Cash at end of year	0				0				0	0	0
Income taxes paid (received)									(78)	(283)	(173)
Interest paid									291	300	320
Eliminations [Member]
Consolidating Statement of Cash Flows
Net income									(2,789)	(2,714)	(2,198)
Net adjustments to reconcile net income to net cash provided by operating activities									298	474	(77)
Net cash provided by operating activities									(2,491)	(2,240)	(2,275)
Proceeds from maturities of fixed maturities									0	0	0
Proceeds from sales of investments:
Fixed maturities									0	0	0
Equity securities									0	0
Equity securities											0
Real estate investments										0	0
Other investments									0	0	(13)
Purchases of investments:
Fixed maturities									0	0	0
Equity securities									0	0
Equity securities											0
Real estate investments									0	0	0
Other investments									0	0	0
Net sales (purchases) of short-term securities									0	0	0
Securities transactions in course of settlement									0	0	0
Acquisition, net of cash acquired										0	13
Other investing activities									0	0	0
Net cash used in investing activities									0	0	0
Treasury stock acquired — share repurchase authorization									0	0	0
Treasury stock acquired — net employee share-based compensation									0	0	0
Dividends paid to shareholders									0	0	0
Payment of debt									32	0	0
Issuance of debt									0	(18)	(14)
Issuance of common stock -- employee share options									0	0	0
Dividends paid to parent company									2,459	2,258	2,289
Net cash used in financing activities									2,491	2,240	2,275
Effect of exchange rate changes on cash									0	0	0
Net increase in cash									0	0	0
Cash at beginning of year				$ 0				$ 0	0	0	0
Cash at end of year	$ 0				$ 0				0	0	0
Income taxes paid (received)									0	0	0
Interest paid									$ 0	$ 0	$ 0

Selected Quarterly Financial _3

Selected Quarterly Financial Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Total revenues	$ 8,063	$ 8,013	$ 7,834	$ 7,671	$ 7,796	$ 7,723	$ 7,477	$ 7,286	$ 31,581	$ 30,282	$ 28,902
Total expenses	6,989	7,581	7,169	6,704	7,050	6,917	6,846	6,508	28,443	27,321	26,172
Income before income taxes	1,074	432	665	967	746	806	631	778	3,138	2,961	2,730
Income tax expense	201	36	108	171	125	97	107	109	516	438	674
Net income	$ 873	$ 396	$ 557	$ 796	$ 621	$ 709	$ 524	$ 669	$ 2,622	$ 2,523	$ 2,056
Net income per common share, basic (in dollars per share)	$ 3.37	$ 1.52	$ 2.11	$ 3.01	$ 2.33	$ 2.65	$ 1.93	$ 2.45	$ 10.01	$ 9.37	$ 7.39
Net income per common share, diluted (in dollars per share)	$ 3.35	$ 1.50	$ 2.10	$ 2.99	$ 2.32	$ 2.62	$ 1.92	$ 2.42	$ 9.92	$ 9.28	$ 7.33

Schedule II (Details) - Condens

Schedule II (Details) - Condensed Income Statement - USD ($) $ in Millions		3 Months Ended								12 Months Ended
		Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Condensed Statement of Income
Net investment income										$ 2,468	$ 2,474	$ 2,397
Net realized investment gains (losses)	[1]									113	114	216
Total revenues		$ 8,063	$ 8,013	$ 7,834	$ 7,671	$ 7,796	$ 7,723	$ 7,477	$ 7,286	31,581	30,282	28,902
Interest expense										344	352	369
Other										4,365	4,297	4,170
Total claims and expenses		6,989	7,581	7,169	6,704	7,050	6,917	6,846	6,508	28,443	27,321	26,172
Income before income taxes		1,074	432	665	967	746	806	631	778	3,138	2,961	2,730
Income tax expense (benefit)		201	36	108	171	125	97	107	109	516	438	674
Net income of subsidiaries										0	0	0
Net income		$ 873	$ 396	$ 557	$ 796	$ 621	$ 709	$ 524	$ 669	2,622	2,523	2,056
Other-than-temporary impairment losses recognized in net realized investment gains (losses)										(4)	(1)
Other-than-temporary impairment losses recognized in net realized investment gains (losses)												(14)
Other-than-temporary impairment losses recognized in other comprehensive income (loss)											0
Other-than-temporary impairment gains recognized in other comprehensive income (loss)										1		1
Travelers [Member]
Condensed Statement of Income
Net investment income										41	32	24
Net realized investment gains (losses)										33	(13)	66
Total revenues										74	19	90
Interest expense										297	304	321
Other										21	20	25
Total claims and expenses										318	324	346
Income before income taxes										(244)	(305)	(256)
Income tax expense (benefit)										(77)	(114)	(130)
Loss before net income of subsidiaries										(167)	(191)	(126)
Net income of subsidiaries										2,789	2,714	2,190
Net income										2,622	2,523	2,064
Other-than-temporary impairment losses recognized in net realized investment gains (losses)										0	0
Other-than-temporary impairment losses recognized in net realized investment gains (losses)												0
Other-than-temporary impairment losses recognized in other comprehensive income (loss)											$ 0
Other-than-temporary impairment gains recognized in other comprehensive income (loss)										$ 0		$ 0

[1]	Total other-than-temporary impairment (OTTI) losses were $(3) million , $(1) million and $(13) million for the years ended December 31, 2019 , 2018 and 2017 , respectively. Of total OTTI, credit losses of $(4) million , $(1) million and $(14) million for the years ended December 31, 2019 , 2018 and 2017 , respectively, were recognized in net realized investment gains. In addition, unrealized gains (losses) from other changes in total OTTI of $1 million , $0 million and $1 million for the years ended December 31, 2019 , 2018 and 2017 , respectively, were recognized in other comprehensive income (loss) as part of changes in net unrealized gains (losses) on investment securities having credit losses recognized in the consolidated statement of income.

Schedule II (Details) - Conde_2

Schedule II (Details) - Condensed Statement of Comprehensive Income - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Condensed Statement of Comprehensive Income
Net income	$ 873	$ 396	$ 557	$ 796	$ 621	$ 709	$ 524	$ 669	$ 2,622	$ 2,523	$ 2,056
Changes in net unrealized gains on investment securities having no credit losses recognized in the consolidated statement of income									2,994	(1,489)	294
Net changes in benefit plan assets and obligations									33	(56)	29
Other comprehensive income (loss) before income taxes									3,140	(1,819)	522
Income tax expense (benefit)									641	(349)	110
Other comprehensive income (loss), net of taxes, before other comprehensive income (loss) of subsidiaries									2,499	(1,470)	412
Other comprehensive income (loss) of subsidiaries									0	0	0
Other comprehensive income (loss), net of taxes									2,499	(1,470)	412
Comprehensive income									5,121	1,053	2,468
Travelers [Member]
Condensed Statement of Comprehensive Income
Net income									2,622	2,523	2,064
Changes in net unrealized gains on investment securities having no credit losses recognized in the consolidated statement of income									4	0	(44)
Net changes in benefit plan assets and obligations									35	(53)	22
Other comprehensive income (loss) before income taxes									39	(53)	(22)
Income tax expense (benefit)									12	(17)	2
Other comprehensive income (loss), net of taxes, before other comprehensive income (loss) of subsidiaries									27	(36)	(24)
Other comprehensive income (loss) of subsidiaries									2,472	(1,434)	436
Other comprehensive income (loss), net of taxes									2,499	(1,470)	412
Comprehensive income									$ 5,121	$ 1,053	$ 2,476

Schedule II (Details) - Conde_3

Schedule II (Details) - Condensed Balance Sheet - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Condensed Balance Sheet
Fixed maturities, at fair value	$ 68,134	$ 63,464
Equity securities, at fair value	425	368
Short-term securities	4,943	3,985
Investment in subsidiaries	0	0
Total assets	110,122	104,233
Debt	6,558	6,564
Total liabilities	84,179	81,339
Common stock (1,750.0 shares authorized; 255.5 and 263.7 shares issued, 255.5 and 263.6 shares outstanding)	23,469	23,144
Retained earnings	36,977	35,204
Accumulated other comprehensive income (loss)	640	(1,859)
Treasury stock, at cost (522.1 and 510.9 shares)	(35,143)	(33,595)
Total shareholders’ equity	25,943	22,894	$ 23,731
Total liabilities and shareholders’ equity	$ 110,122	$ 104,233
Common stock, shares authorized (in shares)	1,750,000,000	1,750,000,000
Common stock, shares issued (in shares)	255,500,000	263,700,000
Common stock, shares outstanding (in shares)	255,500,000	263,600,000
Treasury stock, at cost, shares (in shares)	522,100,000	510,900,000
Travelers [Member]
Condensed Balance Sheet
Fixed maturities, at fair value	$ 91	$ 84
Equity securities, at fair value	209	171
Short-term securities	1,390	1,371
Investment in subsidiaries	30,028	26,993
Other assets	336	649
Total assets	32,054	29,268
Debt	5,865	5,871
Other liabilities	239	496
Total liabilities	6,104	6,367
Common stock (1,750.0 shares authorized; 255.5 and 263.7 shares issued, 255.5 and 263.6 shares outstanding)	23,469	23,144
Retained earnings	36,984	35,211
Accumulated other comprehensive income (loss)	640	(1,859)
Treasury stock, at cost (522.1 and 510.9 shares)	(35,143)	(33,595)
Total shareholders’ equity	25,950	22,901
Total liabilities and shareholders’ equity	$ 32,054	$ 29,268
Common stock, shares authorized (in shares)	1,750,000,000	1,750,000,000
Common stock, shares issued (in shares)	255,500,000	263,700,000
Common stock, shares outstanding (in shares)	255,500,000	263,600,000
Treasury stock, at cost, shares (in shares)	522,100,000	510,900,000

Schedule II (Details) - Conde_4

Schedule II (Details) - Condensed Statement of Cash Flows - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Condensed Statement of Cash Flows
Net income	$ 873	$ 396	$ 557	$ 796	$ 621	$ 709	$ 524	$ 669	$ 2,622	$ 2,523	$ 2,056
Equity in net income of subsidiaries									0	0	0
Deferred federal income tax expense (benefit)									(33)	(13)	337
Other operating activities									535	190	43
Net cash provided by operating activities									5,205	4,380	4,148
Net sales (purchases) of short-term securities									(957)	908	(26)
Acquisition, net of cash acquired									0	(4)	(439)
Net cash used in investing activities									(2,902)	(2,329)	(2,202)
Treasury stock acquired — share repurchase authorization									(1,500)	(1,270)	(1,378)
Treasury stock acquired — net employee share-based compensation									(48)	(51)	(62)
Dividends paid to shareholders									(844)	(814)	(785)
Payment of debt									(500)	(600)	(657)
Issuance of debt									492	591	789
Issuance of common stock -- employee share options									213	132	173
Net cash used in financing activities									(2,187)	(2,012)	(1,920)
Net increase in cash									121	29	37
Cash at beginning of year				373				344	373	344	307
Cash at end of year	494				373				494	373	344
Cash received during the year for taxes									(428)	(408)	(514)
Cash paid during the year for interest									338	347	367
Travelers [Member]
Condensed Statement of Cash Flows
Net income									2,622	2,523	2,064
Equity in net income of subsidiaries									(2,789)	(2,714)	(2,190)
Dividends received from consolidated subsidiaries									2,459	2,258	2,289
Deferred federal income tax expense (benefit)									(2)	28	40
Change in income taxes payable									3	100	3
Other operating activities									(79)	(35)	(174)
Net cash provided by operating activities									2,214	2,160	2,032
Net sales (purchases) of short-term securities									(19)	(141)	397
Other investments, net									(8)	(7)	(34)
Acquisition, net of cash acquired									0	0	(477)
Net cash used in investing activities									(27)	(148)	(114)
Treasury stock acquired — share repurchase authorization									(1,500)	(1,270)	(1,378)
Treasury stock acquired — net employee share-based compensation									(48)	(51)	(62)
Dividends paid to shareholders									(844)	(814)	(785)
Payment of debt									(500)	(600)	(657)
Issuance of debt									492	591	789
Issuance of common stock -- employee share options									213	132	173
Net cash used in financing activities									(2,187)	(2,012)	(1,920)
Net increase in cash									0	0	(2)
Cash at beginning of year				$ 0				$ 0	0	0	2
Cash at end of year	$ 0				$ 0				0	0	0
Cash received during the year for taxes									78	283	173
Cash paid during the year for interest									$ 291	$ 300	$ 320

Schedule II (Details) - Guarant

Schedule II (Details) - Guarantees	12 Months Ended
Schedule II (Details) - Guarantees	Dec. 31, 2019
Condensed Financial Information Disclosure [Abstract]
Schedule II Guarantees Footnote	GUARANTEES The Travelers Companies, Inc. (TRV) fully and unconditionally guarantees the payment of all principal, premiums, if any, and interest on certain debt obligations of its subsidiaries TPC and TIGHI. The guarantees pertain to the $200 million 7.75% notes due 2026 and the $500 million 6.375% notes due 2033. TRV also has contingent obligations for guarantees in connection with the selling of businesses to third parties, certain insurance obligations of a subsidiary and various indemnifications including indemnifications to service providers in the normal course of business. The guarantees and indemnification clauses are often standard contractual terms and include indemnifications for breaches of representations and warranties and in some cases obligations arising from certain liabilities. The terms of these provisions vary in duration and nature.

Schedule II (Details) - Guara_2

Schedule II (Details) - Guarantees Schedule - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Guarantor obligations
Amount of certain debt obligations of Travelers Property Casualty Corp. (TPC) and Travelers Insurance Group Holdings, Inc. (TIGHI) that are fully and unconditionally guaranteed by The Travelers Companies, Inc.	$ 700
Senior Notes [Member] \| 7.75% Senior notes due April 15, 2026 [Member]
Guarantor obligations
Amount of certain debt obligations of Travelers Property Casualty Corp. (TPC) and Travelers Insurance Group Holdings, Inc. (TIGHI) that are fully and unconditionally guaranteed by The Travelers Companies, Inc.	$ 200
Interest rate (percent)	7.75%	7.75%
Senior Notes [Member] \| 6.375% Senior notes due March 15, 2033 [Member]
Guarantor obligations
Amount of certain debt obligations of Travelers Property Casualty Corp. (TPC) and Travelers Insurance Group Holdings, Inc. (TIGHI) that are fully and unconditionally guaranteed by The Travelers Companies, Inc.	$ 500
Interest rate (percent)	6.375%	6.375%
Guarantees on payment of principal, premiums and interest on certain debt obligations [Member] \| Travelers [Member] \| Senior Notes [Member] \| 7.75% Senior notes due April 15, 2026 [Member]
Guarantor obligations
Amount of certain debt obligations of Travelers Property Casualty Corp. (TPC) and Travelers Insurance Group Holdings, Inc. (TIGHI) that are fully and unconditionally guaranteed by The Travelers Companies, Inc.	$ 200
Interest rate (percent)	7.75%
Guarantees on payment of principal, premiums and interest on certain debt obligations [Member] \| Travelers [Member] \| Senior Notes [Member] \| 6.375% Senior notes due March 15, 2033 [Member]
Guarantor obligations
Amount of certain debt obligations of Travelers Property Casualty Corp. (TPC) and Travelers Insurance Group Holdings, Inc. (TIGHI) that are fully and unconditionally guaranteed by The Travelers Companies, Inc.	$ 500
Interest rate (percent)	6.375%

Schedule III (Details)

Schedule III (Details) - USD ($) $ in Millions	12 Months Ended
Schedule III (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Schedule III
Deferred acquisition costs	$ 2,273	$ 2,120	$ 2,025
Claims and claim adjustment expense reserves	51,849	50,668	49,650
Unearned premiums	14,604	13,555	12,915
Earned premiums	28,272	27,059	25,683
Net investment income	2,468	2,474	2,397
Claims and claim adjustment expenses	19,133	18,291	17,467
Amortization of deferred acquisition costs	4,601	4,381	4,166
Other operating expenses	4,709	4,649	4,539
Net written premiums	29,151	27,708	26,219
Reportable segments [Member]
Schedule III
Deferred acquisition costs	2,273	2,120	2,025
Claims and claim adjustment expense reserves	51,836	50,653	49,633
Unearned premiums	14,604	13,555	12,915
Earned premiums	28,272	27,059	25,683
Net investment income	2,468	2,474	2,397
Claims and claim adjustment expenses	19,133	18,291	17,467
Amortization of deferred acquisition costs	4,601	4,381	4,166
Other operating expenses	4,330	4,267	4,138
Net written premiums	29,151	27,708	26,219
Reportable segments [Member] \| Business Insurance [Member]
Schedule III
Deferred acquisition costs	1,161	1,102	1,060
Claims and claim adjustment expense reserves	42,252	41,132	40,352
Unearned premiums	7,540	7,112	6,857
Earned premiums	15,300	14,722	14,146
Net investment income	1,816	1,833	1,786
Claims and claim adjustment expenses	10,963	10,171	9,521
Amortization of deferred acquisition costs	2,503	2,388	2,286
Other operating expenses	2,627	2,623	2,563
Net written premiums	15,629	14,956	14,270
Reportable segments [Member] \| Bond & Specialty Insurance [Member]
Schedule III
Deferred acquisition costs	309	277	258
Claims and claim adjustment expense reserves	3,316	3,255	3,421
Unearned premiums	1,845	1,619	1,515
Earned premiums	2,565	2,420	2,307
Net investment income	233	233	228
Claims and claim adjustment expenses	1,094	772	899
Amortization of deferred acquisition costs	478	454	432
Other operating expenses	483	459	464
Net written premiums	2,739	2,528	2,359
Reportable segments [Member] \| Personal Insurance [Member]
Schedule III
Deferred acquisition costs	803	741	707
Claims and claim adjustment expense reserves	6,268	6,266	5,860
Unearned premiums	5,219	4,824	4,543
Earned premiums	10,407	9,917	9,230
Net investment income	419	408	383
Claims and claim adjustment expenses	7,076	7,348	7,047
Amortization of deferred acquisition costs	1,620	1,539	1,448
Other operating expenses	1,220	1,185	1,111
Net written premiums	10,783	10,224	9,590
Other [Member]
Schedule III
Deferred acquisition costs	0	0	0
Claims and claim adjustment expense reserves	13	15	17
Unearned premiums	0	0	0
Earned premiums	0	0	0
Net investment income	0	0	0
Claims and claim adjustment expenses	0	0	0
Amortization of deferred acquisition costs	0	0	0
Other operating expenses	379	382	401
Net written premiums	$ 0	$ 0	$ 0

Schedule V (Details)

Schedule V (Details) - USD ($) $ in Millions	12 Months Ended
Schedule V (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Reinsurance recoverables [Member]
Schedule V [Roll Forward]
Valuation and qualifying accounts, balance at beginning of period	$ 110	$ 111	$ 116
Valuation and qualifying accounts, charged to costs and expenses	0	0	0
Valuation and qualifying accounts, charged to other accounts	0	0	0
Valuation and qualifying accounts, deductions	18	1	5
Valuation and qualifying accounts, balance at end of period	92	110	111
Allowance for uncollectible premiums receivable from underwriting activities [Member]
Schedule V [Roll Forward]
Valuation and qualifying accounts, balance at beginning of period	54	58	61
Valuation and qualifying accounts, charged to costs and expenses	59	50	38
Valuation and qualifying accounts, charged to other accounts	0	0	0
Valuation and qualifying accounts, deductions	58	54	41
Valuation and qualifying accounts, balance at end of period	55	54	58
Allowance for uncollectible deductibles [Member]
Schedule V [Roll Forward]
Valuation and qualifying accounts, balance at beginning of period	24	26	34
Valuation and qualifying accounts, charged to costs and expenses	(2)	(1)	(2)
Valuation and qualifying accounts, charged to other accounts	0	0	0
Valuation and qualifying accounts, deductions	0	1	6
Valuation and qualifying accounts, balance at end of period	$ 22	$ 24	$ 26

Schedule VI (Details)

Schedule VI (Details) - Consolidated Property and Casualty Insurance Entity [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Supplementary Information Concerning Property-Casualty Insurance Operations
Deferred acquisition costs	$ 2,273	$ 2,120	$ 2,025
Claims and claim adjustment expense reserves	51,836	50,653	49,633
Discount from reserves for unpaid claims	1,155	1,158	1,102
Unearned premiums	14,604	13,555	12,915
Earned premiums	28,272	27,059	25,683
Net investment income	2,468	2,474	2,397
Claims and claim adjustment expenses incurred related to current year	18,854	18,614	17,846
Claims and claim adjustment expenses incurred related to prior year	164	(406)	(458)
Amortization of deferred acquisition costs	4,601	4,381	4,166
Paid claims and claim adjustment expenses	17,794	17,060	16,043
Net written premiums	$ 29,151	$ 27,708	$ 26,219