The Travelers Companies, Inc. (TRV) 10-Q 20 Oct 20 2020 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2020	Oct. 16, 2020
Document and Entity Information
Document type	10-Q
Document quarterly report	true
Document period end date	Sep. 30, 2020
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
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
Common stock shares outstanding		253,308,761
Central index key	0000086312
Amendment flag	false
Current fiscal year end date	--12-31
Document fiscal year focus	2020
Document fiscal period focus	Q3

Consolidated Statement of Incom

Consolidated Statement of Income (Unaudited) - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Revenues
Premiums	$ 7,380	$ 7,179	$ 21,564	$ 21,022
Net investment income	671	622	1,550	1,852
Fee income	101	121	323	346
Net realized investment gains (losses)	37	23	(48)	101
Other revenues	86	68	195	197
Total revenues	8,275	8,013	23,584	23,518
Claims and expenses
Claims and claim adjustment expenses	4,886	5,230	14,782	14,493
Amortization of deferred acquisition costs	1,207	1,169	3,558	3,420
General and administrative expenses	1,109	1,098	3,367	3,280
Interest expense	87	84	256	261
Total claims and expenses	7,289	7,581	21,963	21,454
Income before income taxes	986	432	1,621	2,064
Income tax expense	159	36	234	315
Net income	$ 827	$ 396	$ 1,387	$ 1,749
Net income per share
Basic (in dollars per share)	$ 3.24	$ 1.52	$ 5.44	$ 6.65
Diluted (in dollars per share)	$ 3.23	$ 1.50	$ 5.41	$ 6.59
Weighted average number of common shares outstanding
Basic (in shares)	253.3	259.2	253.5	261.1
Diluted (in shares)	254.3	261.8	254.5	263.4
Cash dividends declared per common share (in dollars per share)	$ 0.85	$ 0.82	$ 2.52	$ 2.41

Consolidated Statement of Compr

Consolidated Statement of Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Statement of Comprehensive Income [Abstract]
Net income	$ 827	$ 396	$ 1,387	$ 1,749
Other comprehensive income:
Changes in net unrealized gains on investment securities having no credit losses recognized in the consolidated statement of income	217	605	2,001	3,129
Changes in net unrealized gains on investment securities having credit losses recognized in the consolidated statement of income	(7)	(3)	(10)	(2)
Net changes in benefit plan assets and obligations	20	14	64	40
Net changes in unrealized foreign currency translation	79	(75)	(137)	(20)
Other comprehensive income before income taxes	309	541	1,918	3,147
Income tax expense	53	122	420	663
Other comprehensive income, net of taxes	256	419	1,498	2,484
Comprehensive income	$ 1,083	$ 815	$ 2,885	$ 4,233

Consolidated Balance Sheet (Una

Consolidated Balance Sheet (Unaudited at September 30, 2020) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Assets
Fixed maturities, available for sale, at fair value (amortized cost $67,736 and $65,281; allowance for expected credit losses of $4 at September 30, 2020)	$ 72,574	$ 68,134
Equity securities, at fair value (cost $381 and $376)	410	425
Real estate investments	957	963
Short-term securities	6,329	4,943
Other investments	3,291	3,419
Total investments	83,561	77,884
Cash	583	494
Investment income accrued	554	618
Premiums receivable (net of allowance for expected credit losses of $96 at September 30, 2020)	8,225	7,909
Reinsurance recoverables (net of allowance for estimated uncollectible reinsurance of $140 at September 30, 2020)	8,317	8,235
Ceded unearned premiums	902	689
Deferred acquisition costs	2,406	2,273
Contractholder receivables (net of allowance for expected credit losses of $21 at September 30, 2020)	4,347	4,599
Goodwill	3,945	3,961
Other intangible assets	318	330
Other assets	3,226	3,130
Total assets	116,384	110,122
Liabilities
Claims and claim adjustment expense reserves	54,418	51,849
Unearned premium reserves	15,542	14,604
Contractholder payables	4,368	4,619
Payables for reinsurance premiums	555	363
Deferred taxes	448	137
Debt	7,050	6,558
Other liabilities	6,154	6,049
Total liabilities	88,535	84,179
Shareholders’ equity
Common stock (1,750.0 shares authorized; 253.3 and 255.5 shares issued and outstanding)	23,646	23,469
Retained earnings	37,679	36,977
Accumulated other comprehensive income	2,138	640
Treasury stock, at cost (525.9 and 522.1 shares)	(35,614)	(35,143)
Total shareholders’ equity	27,849	25,943
Total liabilities and shareholders’ equity	$ 116,384	$ 110,122

Consolidated Balance Sheet Pare

Consolidated Balance Sheet Parentheticals (Unaudited at September 30, 2020) - USD ($) shares in Millions, $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Fixed maturities, available for sale, amortized cost	$ 67,736	$ 65,281
Fixed maturities, available for sale, allowance for expected credit losses	4	0
Equity securities, cost	381	376
Premiums receivable, allowance for expected credit losses	96	49
Reinsurance recoverables, allowance for estimated uncollectible reinsurance	140	92
Contractholder receivables, allowance for expected credit losses	$ 21	$ 20
Common stock, shares authorized (in shares)	1,750	1,750
Common stock, shares issued (in shares)	253.3	255.5
Common stock, shares outstanding (in shares)	253.3	255.5
Treasury stock, at cost (in shares)	525.9	522.1

Consolidated Statement of Chang

Consolidated Statement of Changes in Shareholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Common stock [Member]	Retained earnings [Member]	Retained earnings [Member]Cumulative Effect, Period of Adoption, Adjustment [Member]	Accumulated other comprehensive income (loss), net of tax [Member]	Treasury stock, at cost [Member]	Common shares outstanding [Member]
Shareholders' Equity [Roll Forward]
Shareholders' equity		$ 23,144,000	$ 35,204,000		$ (1,859,000)	$ (33,595,000)
Balance, beginning of year at Dec. 31, 2018		23,144,000	35,204,000		(1,859,000)	(33,595,000)
Shareholders' Equity [Roll Forward]
Employee share-based compensation		173,000
Compensation amortization under share-based plans and other changes		115,000
Shareholders' equity	$ 25,607,000	23,432,000	36,317,000		625,000	(34,767,000)
Net income	1,749,000		1,749,000
Dividends			(636,000)
Other			0
Other comprehensive income	2,484,000				2,484,000
Treasury stock acquired — share repurchase authorization						(1,125,000)
Net shares acquired related to employee share-based compensation plans						(47,000)
Balance, end of period at Sep. 30, 2019	25,607,000	23,432,000	36,317,000		625,000	(34,767,000)
Balance, beginning of year (in shares) at Dec. 31, 2018							263,600,000
Common shares outstanding
Treasury stock acquired - share repurchase authorization (in shares)							(8,000,000)
Net shares issued under employee share-based compensation plans (in shares)							2,500,000
Balance, end of period (in shares) at Sep. 30, 2019							258,100,000
Shareholders' Equity [Roll Forward]
Shareholders' equity		23,372,000	36,135,000		206,000	(34,392,000)
Balance, beginning of year at Jun. 30, 2019		23,372,000	36,135,000		206,000	(34,392,000)
Shareholders' Equity [Roll Forward]
Employee share-based compensation		28,000
Compensation amortization under share-based plans and other changes		32,000
Shareholders' equity	25,607,000	23,432,000	36,317,000		625,000	(34,767,000)
Net income	396,000		396,000
Dividends			(215,000)
Other			1,000
Other comprehensive income	419,000				419,000
Treasury stock acquired — share repurchase authorization						(375,000)
Net shares acquired related to employee share-based compensation plans						0
Balance, end of period at Sep. 30, 2019	25,607,000	23,432,000	36,317,000		625,000	(34,767,000)
Balance, beginning of year (in shares) at Jun. 30, 2019							260,300,000
Common shares outstanding
Treasury stock acquired - share repurchase authorization (in shares)							(2,500,000)
Net shares issued under employee share-based compensation plans (in shares)							300,000
Balance, end of period (in shares) at Sep. 30, 2019							258,100,000
Shareholders' Equity [Roll Forward]
Shareholders' equity	25,607,000	23,432,000	36,317,000		625,000	(34,767,000)
Shareholders' equity	25,943,000	23,469,000	36,977,000	$ (43,000)	640,000	(35,143,000)
Balance, beginning of year at Dec. 31, 2019	25,943,000	23,469,000	36,977,000	(43,000)	640,000	(35,143,000)
Shareholders' Equity [Roll Forward]
Employee share-based compensation		64,000
Compensation amortization under share-based plans and other changes		113,000
Shareholders' equity	$ 27,849,000	23,646,000	37,679,000	$ (43,000)	2,138,000	(35,614,000)
Accounting Standards Update [Extensible List]	us-gaap:AccountingStandardsUpdate201613Member
Net income	$ 1,387,000		1,387,000
Dividends			(646,000)
Other			4,000
Other comprehensive income	1,498,000				1,498,000
Treasury stock acquired — share repurchase authorization	(425,000)					(425,000)
Net shares acquired related to employee share-based compensation plans	(46,000)					(46,000)
Balance, end of period at Sep. 30, 2020	$ 27,849,000	23,646,000	37,679,000		2,138,000	(35,614,000)
Balance, beginning of year (in shares) at Dec. 31, 2019	255,500,000						255,500,000
Common shares outstanding
Treasury stock acquired - share repurchase authorization (in shares)	(3,500,000)						(3,500,000)
Net shares issued under employee share-based compensation plans (in shares)							1,300,000
Balance, end of period (in shares) at Sep. 30, 2020	253,300,000						253,300,000
Shareholders' Equity [Roll Forward]
Shareholders' equity		23,606,000	37,069,000		1,882,000	(35,614,000)
Balance, beginning of year at Jun. 30, 2020		23,606,000	37,069,000		1,882,000	(35,614,000)
Shareholders' Equity [Roll Forward]
Employee share-based compensation		8,000
Compensation amortization under share-based plans and other changes		32,000
Shareholders' equity	$ 27,849,000	23,646,000	37,679,000		2,138,000	(35,614,000)
Net income	827,000		827,000
Dividends			(218,000)
Other			1,000
Other comprehensive income	256,000				256,000
Treasury stock acquired — share repurchase authorization						0
Net shares acquired related to employee share-based compensation plans	(159)					0
Balance, end of period at Sep. 30, 2020	$ 27,849,000	23,646,000	37,679,000		2,138,000	(35,614,000)
Balance, beginning of year (in shares) at Jun. 30, 2020							253,200,000
Common shares outstanding
Treasury stock acquired - share repurchase authorization (in shares)	0						0
Net shares issued under employee share-based compensation plans (in shares)							100,000
Balance, end of period (in shares) at Sep. 30, 2020	253,300,000						253,300,000
Shareholders' Equity [Roll Forward]
Shareholders' equity	$ 27,849,000	$ 23,646,000	$ 37,679,000		$ 2,138,000	$ (35,614,000)

Consolidated Statement of Cash

Consolidated Statement of Cash Flows (Unaudited) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Cash flows from operating activities
Net income	$ 1,387	$ 1,749
Adjustments to reconcile net income to net cash provided by operating activities:
Net realized investment (gains) losses	48	(101)
Depreciation and amortization	577	581
Deferred federal income tax benefit	(67)	(10)
Amortization of deferred acquisition costs	3,558	3,420
Equity in (income) loss from other investments	32	(196)
Premiums receivable	(324)	(611)
Reinsurance recoverables	(150)	212
Deferred acquisition costs	(3,694)	(3,619)
Claims and claim adjustment expense reserves	2,673	927
Unearned premium reserves	960	1,350
Other operating activities	(382)	91
Net cash provided by operating activities	4,618	3,793
Cash flows from investing activities
Proceeds from maturities of fixed maturities	5,241	4,895
Proceeds from sales of investments:
Fixed maturities	1,994	1,801
Equity securities	76	99
Other investments	184	346
Purchases of investments:
Fixed maturities	(9,951)	(8,234)
Equity securities	(80)	(62)
Real estate investments	(33)	(95)
Other investments	(321)	(369)
Net purchases of short-term securities	(1,387)	(617)
Securities transactions in course of settlement	522	432
Other investing activities	(222)	(243)
Net cash used in investing activities	(3,977)	(2,047)
Cash flows from financing activities
Treasury stock acquired — share repurchase authorization	(425)	(1,125)
Treasury stock acquired — net employee share-based compensation	(46)	(47)
Dividends paid to shareholders	(643)	(633)
Payment of debt	0	(500)
Issuance of debt	490	492
Issuance of common stock — employee share options	72	206
Net cash used in financing activities	(552)	(1,607)
Effect of exchange rate changes on cash	0	(4)
Net increase in cash	89	135
Cash at beginning of year	494	373
Cash at end of period	583	508
Supplemental disclosure of cash flow information
Income taxes paid	413	367
Interest paid	$ 226	$ 231

Basis of Presentation and Accou

Basis of Presentation and Accounting Policies	9 Months Ended
	Sep. 30, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation and Accounting Policies	BASIS OF PRESENTATION AND ACCOUNTING POLICIES Basis of Presentation The interim consolidated financial statements include the accounts of The Travelers Companies, Inc. (together with its subsidiaries, the Company). These financial statements are prepared in conformity with U.S. generally accepted accounting principles (GAAP) and are unaudited. In the opinion of the Company’s management, all adjustments necessary for a fair presentation have been reflected. Certain financial information that is normally included in annual financial statements prepared in accordance with GAAP, but that is not required for interim reporting purposes, has been omitted. All material intercompany transactions and balances have been eliminated. The accompanying interim consolidated financial statements and related notes should be read in conjunction with the Company’s consolidated financial statements and related notes included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2019 (the Company’s 2019 Annual Report). The preparation of the interim consolidated financial statements in conformity with 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 interim consolidated financial statements and the reported amounts of revenues and claims and expenses during the reporting period. Actual results could differ from those estimates. Certain reclassifications have been made to the 2019 financial statements to conform to the 2020 presentation. Adoption of Accounting Standards Registered Debt Offerings that Include Credit Enhancements from an Affiliate In March 2020, the Securities and Exchange Commission (SEC) adopted amendments to the financial disclosure requirements related to certain debt securities, including registered debt securities issued by a wholly-owned, operating subsidiary that are fully and unconditionally guaranteed by the parent company. Prior to the amendments, a parent guarantor was required to provide condensed consolidating financial information for so long as the guaranteed securities were outstanding, regardless of whether the subsidiary issuer could have suspended its public reporting obligations under the applicable SEC requirements with respect to the securities. In accordance with the amended requirements, a parent guarantor may cease providing the condensed consolidating financial information if the corresponding subsidiary issuer’s public reporting obligation is suspended. The amendments to the financial disclosure requirements are effective on January 4, 2021; however, the SEC permits voluntary compliance in advance of the effective date. The Company elected to apply the amended requirements beginning with the quarter ended March 31, 2020, and is no longer providing condensed consolidating financial information that resulted from the registered debt obligations of its subsidiaries, Travelers Property Casualty Corp. and Travelers Insurance Group Holdings Inc., that were disclosed in note 8 of the financial statements in the Company’s 2019 Annual Report . Financial Instruments - Credit Losses: Measurement of Credit Losses on Financial Instruments In June 2016, the Financial Accounting Standards Board 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 previous 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 Company adopted the updated guidance for the quarter ended March 31, 2020. For additional information regarding accounting standards that the Company adopted during the periods presented, see note 1 of notes to the consolidated financial statements in the Company’s 2019 Annual Report. Accounting Standards Not Yet Adopted For information regarding accounting standards that the Company has not yet adopted, see the “Other Accounting Standards Not Yet Adopted” section of note 1 of notes to the consolidated financial statements in the Company’s 2019 Annual Report. Accounting Policies The following accounting policies have been updated to reflect the Company's adoption of Financial Instruments - Credit Losses: Measurement of Credit Losses on Financial Instruments as described above. Investment Impairments The Company conducts a periodic review to identify and evaluate invested assets that may have credit impairments. Credit Impairments of Fixed Maturity Investments Some of the factors considered in assessing impairment of fixed maturity investments due to credit-related factors 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; and (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. Beginning on January 1, 2020, credit losses are recognized through an allowance account. See note 1 - Adoption of Accounting Standards - Financial Instruments - Credit Losses: Measurement of Credit Losses on Financial Instruments for additional information. 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 (non-credit factors) is reported in other comprehensive income. The allowance is adjusted for any additional credit losses and subsequent recoveries. Upon recognizing a credit loss, the cost basis is not adjusted. For fixed maturity investments where the Company records a credit loss, a determination is made as to the cause of the impairment and whether the Company expects a recovery in the value. For fixed maturity investments where the Company expects a recovery in value, the constant effective yield method is utilized, and the investment is amortized to par. 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). The new cost basis of the investment is the previous amortized cost basis less the impairment recognized in net realized investment gains (losses). The new cost basis is not adjusted for any subsequent recoveries in fair value. The Company reports investment income accrued separately from fixed maturity investments, available for sale, and has elected not to measure an allowance for credit losses for investment income accrued. Investment income accrued is written off through net realized investment gains (losses) at the time the issuer of the bond defaults or is expected to default on payments. Uncollectible available-for-sale debt securities are written-off when the Company determines that no additional payments of principal or interest will be received. Reinsurance Recoverables Amounts recoverable from reinsurers are estimated in a manner consistent with the associated claim liability. Included in reinsurance recoverables are amounts related to certain structured settlements. The Company reports its reinsurance recoverables net of an allowance for estimated uncollectible reinsurance. 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. For structured settlements, the allowance is also based upon the Company’s ongoing review of life insurers’ creditworthiness and estimated amounts of coverage that would be available from state guaranty funds if a life insurer defaults. A probability-of-default methodology which reflects current and forecasted economic conditions is used to estimate the amount of uncollectible reinsurance due to credit-related factors and the estimate is reported in an allowance for estimated uncollectible reinsurance. The allowance also includes estimated uncollectible amounts related to dispute risk with reinsurers. Amounts deemed to be uncollectible, including amounts due from known insolvent reinsurers, are written off against the allowance. Changes in the allowance, as well as 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. 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 both contractholder payables and contractholder receivables. Contractholder receivables are reported net of an allowance for expected credit losses. The allowance is based upon the Company’s ongoing review of amounts outstanding, changes in policyholder credit standing, and other relevant factors. A probability-of-default methodology which reflects current and forecasted economic conditions is used to estimate the allowance for expected credit losses. 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 expected credit losses. The allowance is based upon the Company’s ongoing review of amounts outstanding, historical loss data, including delinquencies and write-offs, current and forecasted economic conditions and other relevant factors. Credit risk is partially mitigated by the Company’s ability to cancel the policy if the policyholder does not pay the premium.

Segment Information

Segment Information	9 Months Ended
	Sep. 30, 2020
Segment Reporting [Abstract]
Segment Information	SEGMENT INFORMATION Nature of Operations The Company’s results are reported in the following three business segments — Business Insurance, Bond & Specialty Insurance and Personal Insurance. These segments reflect the manner in which the Company’s businesses are currently managed and represent an aggregation of products and services based on the type of customer, how the business is marketed and the manner in which risks are underwritten. For more information regarding the Company’s nature of operations, see the “Nature of Operations ” section of note 1 of notes to the consolidated financial statements in the Company’s 2019 Annual Report. The following tables summarize the components of the Company’s revenues, income and total assets by reportable business segments: (For the three months ended September 30, in millions) Business Bond & Specialty Personal Total 2020 Premiums $ 3,841 $ 723 $ 2,816 $ 7,380 Net investment income 498 58 115 671 Fee income 95 — 6 101 Other revenues 58 7 21 86 Total segment revenues (1) $ 4,492 $ 788 $ 2,958 $ 8,238 Segment income (1) $ 365 $ 115 $ 392 $ 872 2019 Premiums $ 3,882 $ 653 $ 2,644 $ 7,179 Net investment income 457 59 106 622 Fee income 114 — 7 121 Other revenues 39 7 22 68 Total segment revenues (1) $ 4,492 $ 719 $ 2,779 $ 7,990 Segment income (1) $ 179 $ 139 $ 131 $ 449 _________________________________________________________ (1) Segment revenues for reportable business segments exclude net realized investment gains (losses) and revenues included in "interest expense and other." Segment income for reportable business segments equals net income excluding the after-tax impact of net realized investment gains (losses) and income (loss) from "interest expense and other." (For the nine months ended September 30, in millions) Business Bond & Specialty Personal Total 2020 Premiums $ 11,440 $ 2,083 $ 8,041 $ 21,564 Net investment income 1,131 155 264 1,550 Fee income 305 — 18 323 Other revenues 125 17 53 195 Total segment revenues (1) $ 13,001 $ 2,255 $ 8,376 $ 23,632 Segment income (1) $ 596 $ 309 $ 738 $ 1,643 2019 Premiums $ 11,407 $ 1,891 $ 7,724 $ 21,022 Net investment income 1,365 173 314 1,852 Fee income 329 — 17 346 Other revenues 112 19 65 196 Total segment revenues (1) $ 13,213 $ 2,083 $ 8,120 $ 23,416 Segment income (1) $ 944 $ 451 $ 497 $ 1,892 _________________________________________________________ (1) Segment revenues for reportable business segments exclude net realized investment gains (losses) and revenues included in "interest expense and other." Segment income for reportable business segments equals net income excluding the after-tax impact of net realized investment gains (losses) and income (loss) from "interest expense and other." Business Segment Reconciliations Three Months Ended Nine Months Ended (in millions) 2020 2019 2020 2019 Revenue reconciliation Earned premiums Business Insurance: Domestic: Workers’ compensation $ 851 $ 969 $ 2,568 $ 2,891 Commercial automobile 698 672 2,058 1,947 Commercial property 522 496 1,544 1,429 General liability 605 594 1,786 1,746 Commercial multi-peril 891 872 2,660 2,568 Other 15 12 38 29 Total Domestic 3,582 3,615 10,654 10,610 International 259 267 786 797 Total Business Insurance 3,841 3,882 11,440 11,407 Bond & Specialty Insurance: Domestic: Fidelity and surety 277 265 805 769 General liability 310 276 893 799 Other 60 54 178 159 Total Domestic 647 595 1,876 1,727 International 76 58 207 164 Total Bond & Specialty Insurance 723 653 2,083 1,891 Personal Insurance: Domestic: Automobile 1,391 1,344 3,896 3,962 Homeowners and Other 1,262 1,119 3,659 3,236 Total Domestic 2,653 2,463 7,555 7,198 International 163 181 486 526 Total Personal Insurance 2,816 2,644 8,041 7,724 Total earned premiums 7,380 7,179 21,564 21,022 Net investment income 671 622 1,550 1,852 Fee income 101 121 323 346 Other revenues 86 68 195 196 Total segment revenues 8,238 7,990 23,632 23,416 Other revenues — — — 1 Net realized investment gains (losses) 37 23 (48) 101 Total revenues $ 8,275 $ 8,013 $ 23,584 $ 23,518 Income reconciliation, net of tax Total segment income $ 872 $ 449 $ 1,643 $ 1,892 Interest Expense and Other (1) (74) (71) (219) (222) Core income 798 378 1,424 1,670 Net realized investment gains (losses) 29 18 (37) 79 Net income $ 827 $ 396 $ 1,387 $ 1,749 _________________________________________________________ (1) The primary component of Interest Expense and Other was after-tax interest expense of $69 million and $66 million for the three months ended September 30, 2020 and 2019, respectively, and $202 million and $206 million for the nine months ended September 30, 2020 and 2019, respectively. (in millions) September 30, December 31, Asset reconciliation Business Insurance $ 88,040 $ 83,896 Bond & Specialty Insurance 9,483 8,599 Personal Insurance 18,230 17,015 Total assets by reportable segment 115,753 109,510 Other assets (1) 631 612 Total consolidated assets $ 116,384 $ 110,122 _________________________________________________________

Investments

Investments	9 Months Ended
	Sep. 30, 2020
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 Cost Allowance for Expected Credit Losses Gross Unrealized Fair Value (at September 30, 2020, in millions) Gains Losses U.S. Treasury securities and obligations of U.S. government and government agencies and authorities $ 2,083 $ — $ 43 $ — $ 2,126 Obligations of states, municipalities and political subdivisions: Local general obligation 17,019 — 1,267 8 18,278 Revenue 11,871 — 829 6 12,694 State general obligation 1,160 — 91 — 1,251 Pre-refunded 2,458 — 160 — 2,618 Total obligations of states, municipalities and political subdivisions 32,508 — 2,347 14 34,841 Debt securities issued by foreign governments 952 — 27 — 979 Mortgage-backed securities, collateralized mortgage obligations and pass-through securities 2,572 — 158 — 2,730 All other corporate bonds 29,599 4 2,314 35 31,874 Redeemable preferred stock 22 — 2 — 24 Total $ 67,736 $ 4 $ 4,891 $ 49 $ 72,574 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 Pre-refunded bonds of $2.62 billion and $2.06 billion at September 30, 2020 and December 31, 2019, 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. Proceeds from sales of fixed maturities classified as available for sale were $1.99 billion and $1.80 billion during the nine months ended September 30, 2020 and 2019, respectively. Gross gains of $52 million and $51 million and gross losses of $3 million and $6 million were realized on those sales during the nine months ended September 30, 2020 and 2019, respectively. Equity Securities The cost and fair value of investments in equity securities were as follows: Fair (at September 30, 2020, in millions) Cost Gross Gains Gross Losses Value Public common stock $ 346 $ 44 $ 22 $ 368 Non-redeemable preferred stock 35 8 1 42 Total $ 381 $ 52 $ 23 $ 410 Fair (at December 31, 2019, in millions) Cost Gross Gains Gross Losses Value Public common stock $ 341 $ 45 $ 3 $ 383 Non-redeemable preferred stock 35 7 — 42 Total $ 376 $ 52 $ 3 $ 425 For the nine months ended September 30, 2020 and 2019, the Company recognized $(14) million and $49 million of net gains (losses) on equity securities still held as of September 30, 2020 and 2019, respectively. Net realized investment losses on equity securities still held for the first nine months of 2020 were driven by the impact of changes in fair value attributable to the volatility in global financial markets associated with the global pandemic beginning in March 2020 related to the novel coronavirus COVID-19. Unrealized Investment Losses The following tables summarize, for all investments in an unrealized loss position at September 30, 2020 and December 31, 2019, 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 herein and in note 4 of notes to the consolidated financial statements in the Company’s 2019 Annual Report. The Company also relies upon estimates of several credit and non-credit factors in its review and evaluation of individual investments, using the process described in note 1 of notes to the consolidated financial statements to determine whether credit impairment exists. Less than 12 months 12 months or longer Total (at September 30, 2020, in millions) Fair Gross Fair Gross Fair Gross Fixed maturities U.S. Treasury securities and obligations of U.S. government and government agencies and authorities $ 169 $ — $ — $ — $ 169 $ — Obligations of states, municipalities and political subdivisions 1,751 14 — — 1,751 14 Debt securities issued by foreign governments 14 — — — 14 — Mortgage-backed securities, collateralized mortgage obligations and pass-through securities 11 — 1 — 12 — All other corporate bonds 1,095 28 120 7 1,215 35 Total $ 3,040 $ 42 $ 121 $ 7 $ 3,161 $ 49 Less than 12 months 12 months or longer Total (at December 31, 2019, in millions) Fair Gross Fair Gross Fair Gross 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 $ 2,900 $ 19 $ 1,145 $ 10 $ 4,045 $ 29 At September 30, 2020, the amount of gross unrealized losses for all fixed maturity investments reported at fair value for which fair value was less than 80% of amortized cost was not significant. Credit Impairment Charges The following tables present changes in the allowance for expected credit losses on fixed maturities classified as available for sale: Fixed Maturities (for the three months ended September 30, 2020 in millions) Mortgage-Backed Securities, Collateralized Mortgage Obligations and Pass-Through Securities All Other Corporate Bonds Total Balance, July 1, 2020 $ — $ 8 $ 8 Additions for expected credit losses on securities where no credit losses were previously recognized — 1 1 Additions (reductions) for expected credit losses on securities where credit losses were previously recognized — (3) (3) Reductions due to sales/defaults of credit-impaired securities — (2) (2) Reductions for impairments of securities which the Company intends to sell or more likely than not will be required to sell (1) — — — Balance, September 30, 2020 $ — $ 4 $ 4 Fixed Maturities (for the nine months ended September 30, 2020 in millions) Mortgage-Backed Securities, Collateralized Mortgage Obligations and Pass-Through Securities All Other Corporate Bonds Total Balance, January 1, 2020 $ — $ — $ — Additions for expected credit losses on securities where no credit losses were previously recognized — 9 9 Additions (reductions) for expected credit losses on securities where credit losses were previously recognized — (3) (3) Reductions due to sales/defaults of credit-impaired securities — (2) (2) Reductions for impairments of securities which the Company intends to sell or more likely than not will be required to sell (1) — — — Balance, September 30, 2020 $ — $ 4 $ 4 _________________________________________________________ (1) Credit impairment charges recognized in net realized investment gains (losses) for the nine months ended September 30, 2020 included $14 million of credit losses on fixed maturity securities which the Company intends to sell. An allowance for expected credit losses was not previously recorded for these securities. Total net credit impairment charges (recoveries) included in net realized investment gains (losses) in the consolidated statement of income were $(4) million and $0 million for the three months ended September 30, 2020 and 2019, respectively, and $58 million and $2 million for the nine months ended September 30, 2020 and 2019, respectively. Additionally, net realized investment gains (losses) in the first nine months of 2020 included $40 million of realized losses related to the other-than-temporary impairment of the carrying value of an equity method investment included in other investments. Credit losses related to the fixed maturity portfolio for the three months and nine months ended September 30, 2020 and 2019 represented less than 1% of the fixed maturity portfolio on a pre-tax basis and less than 1% of shareholders’ equity on an after-tax basis at both September 30, 2020 and 2019.

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2020
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 Company utilized a pricing service to estimate fair value measurements for approximately 99% of its fixed maturities at both September 30, 2020 and December 31, 2019. 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 $89 million and $73 million at September 30, 2020 and December 31, 2019, 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 $3 million and $28 million at September 30, 2020 and December 31, 2019, 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. For more information regarding the valuation of the Company’s fixed maturities, equity securities and other investments, see note 4 of notes to the consolidated financial statements in the Company’s 2019 Annual Report. 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 September 30, 2020 and December 31, 2019 was $7 million and $8 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 September 30, 2020, 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 $ 2,126 $ 2,126 $ — $ — Obligations of states, municipalities and political subdivisions 34,841 — 34,830 11 Debt securities issued by foreign governments 979 — 979 — Mortgage-backed securities, collateralized mortgage obligations and pass-through securities 2,730 — 2,730 — All other corporate bonds 31,874 6 31,787 81 Redeemable preferred stock 24 — 24 — Total fixed maturities 72,574 2,132 70,350 92 Equity securities Public common stock 368 368 — — Non-redeemable preferred stock 42 21 21 — Total equity securities 410 389 21 — Other investments 48 14 — 34 Total $ 73,032 $ 2,535 $ 70,371 $ 126 Other liabilities $ 7 $ — $ — $ 7 (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 There was no significant activity in Level 3 of the hierarchy during the nine months ended September 30, 2020 or the year ended December 31, 2019. 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 September 30, 2020, in millions) Carrying Fair Level 1 Level 2 Level 3 Financial assets Short-term securities $ 6,329 $ 6,329 $ 977 $ 5,307 $ 45 Financial liabilities Debt $ 6,950 $ 9,083 $ — $ 9,083 $ — Commercial paper $ 100 $ 100 $ — $ 100 $ — (at December 31, 2019, in millions) Carrying Fair 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 $ — The Company had no material assets or liabilities that were measured at fair value on a non-recurring basis during the nine months ended September 30, 2020 or year ended December 31, 2019.

Allowance for Expected Credit L

Allowance for Expected Credit Losses	9 Months Ended
	Sep. 30, 2020
Credit Loss [Abstract]
Allowance for Expected Credit Losses	ALLOWANCE FOR EXPECTED CREDIT LOSSES Premiums Receivable The following tables present the balances of premiums receivable, net of the allowance for expected credit losses, at September 30, 2020 and January 1, 2020, and the changes in the allowance for expected credit losses for the three months and nine months ended September 30, 2020. At and For the Three Months Ended September 30, 2020 At and For the Nine Months Ended September 30, 2020 (in millions) Premiums Receivable, Net of Allowance for Expected Credit Losses Allowance for Expected Credit Losses Premiums Receivable, Net of Allowance for Expected Credit Losses Allowance for Expected Credit Losses Balance, beginning of period $ 8,459 $ 94 $ 7,909 $ 49 Current period change for expected credit losses 17 84 Write-offs of uncollectible premiums receivable 15 37 Balance, end of period $ 8,225 $ 96 $ 8,225 $ 96 Reinsurance Recoverables The following tables present the balances of reinsurance recoverables, net of the allowance for estimated uncollectible reinsurance, at September 30, 2020 and January 1, 2020, and the changes in the allowance for estimated uncollectible reinsurance for the three months and nine months ended September 30, 2020. At and For the Three Months Ended September 30, 2020 At and For the Nine Months Ended September 30, 2020 (in millions) Reinsurance Recoverables, Net of Allowance for Estimated Uncollectible Reinsurance Allowance for Estimated Uncollectible Reinsurance Reinsurance Recoverables, Net of Allowance for Estimated Uncollectible Reinsurance Allowance for Estimated Uncollectible Reinsurance Balance, beginning of period $ 8,093 $ 156 $ 8,235 $ 92 Cumulative effect of adoption of updated accounting guidance for credit losses at January 1, 2020 — 53 Current period change for estimated uncollectible reinsurance (16) (5) Write-offs of uncollectible reinsurance recoverables — — Balance, end of period $ 8,317 $ 140 $ 8,317 $ 140 Of the total reinsurance recoverables at September 30, 2020, after deducting mandatory pools and associations and before allowances for estimated uncollectible reinsurance, $5.82 billion, or 88%, were rated by A.M. Best Company. The Company utilizes updated A.M. Best credit ratings on a quarterly basis when determining the allowance. Of the total rated by A.M. Best Company, 93% were rated A- or better. The remaining 12% of reinsurance recoverables were comprised of the following: 6% related to captive insurance companies, 1% related to the Company’s participation in voluntary pools, and 5% were balances from other companies not rated by A.M. Best Company. Certain of the Company's reinsurance recoverables are collateralized by letters of credit, funds held or trust agreements. Contractholder Receivables The following tables present the balances of contractholder receivables, net of the allowance for expected credit losses, at September 30, 2020 and January 1, 2020, and the changes in the allowance for expected credit losses for the three months and nine months ended September 30, 2020. At and For the Three Months Ended September 30, 2020 At and For the Nine Months Ended September 30, 2020 (in millions) Contractholder Receivables, Net of Allowance for Expected Credit Losses Allowance for Expected Credit Losses Contractholder Receivables, Net of Allowance for Expected Credit Losses Allowance for Expected Credit Losses Balance, beginning of period $ 4,314 $ 22 $ 4,599 $ 20 Current period change for expected credit losses — 2 Write-offs of uncollectible contractholder receivables 1 1 Balance, end of period $ 4,347 $ 21 $ 4,347 $ 21

Goodwill and Other Intangible A

Goodwill and Other Intangible Assets	9 Months Ended
	Sep. 30, 2020
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. (in millions) September 30, December 31, Business Insurance $ 2,589 $ 2,601 Bond & Specialty Insurance 550 550 Personal Insurance 780 784 Other 26 26 Total $ 3,945 $ 3,961 Other Intangible Assets The following tables present a summary of the Company’s other intangible assets by major asset class. (at September 30, 2020, in millions) Gross Accumulated Net Subject to amortization Customer-related $ 98 $ 28 $ 70 Contract-based (1) 204 182 22 Total subject to amortization 302 210 92 Not subject to amortization 226 — 226 Total $ 528 $ 210 $ 318 (at December 31, 2019, in millions) Gross Accumulated 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 _________________________________________________________ (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 $4 million for each of the three months ended September 30, 2020 and 2019, and $11 million and $12 million for the nine months ended September 30, 2020 and 2019, respectively. Amortization expense for all intangible assets subject to amortization is estimated to be $4 million for the remainder of 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 $1 million for the remainder of 2020, $4 million in 2021, $3 million in 2022, $3 million in 2023 and $2 million in 2024.

Insurance Claim Reserves

Insurance Claim Reserves	9 Months Ended
	Sep. 30, 2020
Insurance Loss Reserves [Abstract]
Insurance Claim Reserves	INSURANCE CLAIM RESERVES Claims and claim adjustment expense reserves were as follows: (in millions) September 30, December 31, Property-casualty $ 54,406 $ 51,836 Accident and health 12 13 Total $ 54,418 $ 51,849 The following table presents a reconciliation of beginning and ending property casualty reserve balances for claims and claim adjustment expenses: Nine Months Ended September 30, (in millions) 2020 2019 Claims and claim adjustment expense reserves at beginning of year $ 51,836 $ 50,653 Less reinsurance recoverables on unpaid losses 8,035 8,182 Cumulative effect of adoption of updated accounting guidance for credit losses at January 1, 2020 53 — Net reserves at beginning of year 43,854 42,471 Estimated claims and claim adjustment expenses for claims arising in the current year 14,809 14,193 Estimated increase (decrease) in claims and claim adjustment expenses for claims arising in prior years (108) 214 Total increases 14,701 14,407 Claims and claim adjustment expense payments for claims arising in: Current year 4,960 5,174 Prior years 7,246 8,034 Total payments 12,206 13,208 Unrealized foreign exchange (gain) loss (62) 12 Net reserves at end of period 46,287 43,682 Plus reinsurance recoverables on unpaid losses 8,119 7,916 Claims and claim adjustment expense reserves at end of period $ 54,406 $ 51,598 Gross claims and claim adjustment expense reserves at September 30, 2020 increased by $2.57 billion from December 31, 2019, primarily reflecting the impacts of (i) catastrophe losses in the first nine months of 2020, (ii) loss cost trends for the current accident year and (iii) reduced claim settlement activity largely due to the disruptions in the judicial system related to COVID-19. Reinsurance recoverables on unpaid losses at September 30, 2020 increased by $84 million from December 31, 2019, primarily reflecting the impacts of catastrophe losses in the first nine months of 2020 and the asbestos reserve increase in the third quarter of 2020, partially offset by cash collections in the first nine months of 2020 and the $53 million increase in the allowance for estimated uncollectible reinsurance from the cumulative effect of adoption of updated accounting guidance for credit losses Beginning in late March, in response to COVID-19, a number of states have enacted changes designed to effectively expand workers’ compensation coverage by creating a presumption of compensability for certain types of workers. In addition, other states are considering similar changes. Depending on the number of states that institute such changes and the terms of the changes, the Company could experience elevated claims frequency and severity for its workers’ compensation line, which could have a material adverse effect on its results of operations. PG&E Corporation and Pacific Gas and Electric Company (together, PG&E) emerged from bankruptcy on July 1, 2020, the date the Debtors' and Shareholder Proponents' Joint Chapter 11 Plan of Reorganization Dated June 19, 2020 (the Plan) became effective. In accordance with the terms of the Plan, PG&E funded a trust from which the Company and other subrogation claimants have received, and/or will receive, recoveries related to the 2017 and 2018 California wildfires. In the third quarter of 2020, the Company recognized a subrogation benefit related to these claims of $403 million (the Company's estimate of its total recoveries from the trust prior to its expiration in 2025, pre-tax and net of expenses and amounts that inure to the benefit of the Company's reinsurers) and received payments from the trust of $366 million . Prior Year Reserve Development The following disclosures regarding reserve development are on a “net of reinsurance” basis. For the nine months ended September 30, 2020 and 2019, estimated claims and claim adjustment expenses incurred included $108 million and $(214) million, respectively, of net favorable (unfavorable) development for claims arising in prior years, including $171 million and $(120) million, respectively, of net favorable (unfavorable) prior year reserve development, and $36 million and $37 million, respectively, of accretion of discount in each period that impacted the Company's results of operations. Business Insurance. Net unfavorable prior year reserve development in the third quarter of 2020 totaled $220 million, primarily driven by: • Asbestos reserves - an increase of $295 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 primary and excess coverages primarily due to an increase to the reserves in the Company's run-off operations related to a single insured arising out of policies issued more than 20 years ago; and • Commercial multi-peril (excluding PG&E subrogation recoveries and asbestos and environmental) - higher than expected loss experience in the segment's domestic operations for recent accident years. Partially offset by: • PG&E subrogation recoveries - $81 million of recoveries described above; and • Workers' compensation - better than expected loss experience in the segment's domestic operations for multiple accident years. Net unfavorable prior year reserve development in the third quarter of 2019 totaled $316 million, primarily driven by: • Asbestos reserves - an increase of $220 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 primary and excess coverages for multiple accident years; and • Commercial automobile - higher than expected loss experience in the segment's domestic operations for recent accident years. Partially offset by: • Workers' compensation - better than expected loss experience in the segment's domestic operations for recent accident years. Net unfavorable prior year reserve development in the first nine months of 2020 totaled $215 million, primarily driven by: • Asbestos reserves - the increase of $295 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 primary and excess coverages for recent accident years; • Commercial automobile - higher than expected loss experience in the segment's domestic operations for recent accident years; and • Commercial multi-peril (excluding PG&E subrogation recoveries and asbestos and environmental) - higher than expected loss experience in the segment's domestic operations for recent accident years. Partially offset by: • Workers' compensation - better than expected loss experience in the segment's domestic operations for multiple accident years; • Commercial property (excluding PG&E subrogation recoveries) - better than expected loss experience in the segment's domestic operations for multiple accident years; and • PG&E subrogation recoveries - $81 million of recoveries described above. Net unfavorable prior year reserve development in the first nine months of 2019 totaled $266 million, primarily driven by: • 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 of the enactment of legislation by a number of states, which extended the statute of limitations for childhood sexual molestation claims; • Asbestos reserves - the increase of $220 million, primarily in the segment's domestic general liability product line; • Commercial automobile - higher than expected loss experience in the segment's domestic operations for recent accident years; • Environmental reserves - an increase of $68 million, primarily in the segment's domestic general liability product line; and • Commercial multi-peril - higher than expected loss experience in the segment's domestic operations for recent accident years. 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. There was no net prior year reserve development in the third quarter of 2020. Net unfavorable prior year reserve development in the first nine months of 2020 totaled $33 million, primarily driven by higher than expected loss experience in the segment's domestic operations in the general liability product line for recent accident years. Net favorable prior year reserve development in the third quarter and first nine months of 2019 totaled $3 million and $45 million, respectively, primarily driven by better than expected loss experience in the segment's domestic operations in the general liability product line for multiple accident years.

Other Comprehensive Income and

Other Comprehensive Income and Accumulated Other Comprehensive Income	9 Months Ended
	Sep. 30, 2020
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 tables present the changes in the Company’s accumulated other comprehensive income (loss) (AOCI) for the three months and nine months ended September 30, 2020. Changes in Net Unrealized Gains on Investment Securities (in millions) Having No Credit Having Credit Net Benefit Plan Assets and Net Unrealized Total Accumulated Balance, June 30, 2020 $ 3,459 $ 187 $ (811) $ (953) $ 1,882 Other comprehensive income (loss) (OCI) before reclassifications, net of tax 189 (5) — 74 258 Amounts reclassified from AOCI, net of tax (18) — 16 — (2) Net OCI, current period 171 (5) 16 74 256 Balance, September 30, 2020 $ 3,630 $ 182 $ (795) $ (879) $ 2,138 Changes in Net Unrealized Gains on Investment Securities (in millions) Having No Credit Losses Recognized in the Consolidated Statement of Income Having Credit Net Benefit Plan Assets and Obligations Recognized in Shareholders’ Equity Net Unrealized Foreign Currency Translation Total Accumulated Other Comprehensive Income Balance, December 31, 2019 $ 2,057 $ 189 $ (846) $ (760) $ 640 Other comprehensive income (loss) (OCI) before reclassifications, net of tax 1,597 (7) 1 (119) 1,472 Amounts reclassified from AOCI, net of tax (24) — 50 — 26 Net OCI, current period 1,573 (7) 51 (119) 1,498 Balance, September 30, 2020 $ 3,630 $ 182 $ (795) $ (879) $ 2,138 The following table presents the pre-tax components of the Company’s other comprehensive income and the related income tax expense. Three Months Ended Nine Months Ended (in millions) 2020 2019 2020 2019 Changes in net unrealized gains on investment securities: Having no credit losses recognized in the consolidated statement of income $ 217 $ 605 $ 2,001 $ 3,129 Income tax expense 46 127 428 661 Net of taxes 171 478 1,573 2,468 Having credit losses recognized in the consolidated statement of income (7) (3) (10) (2) Income tax benefit (2) (1) (3) (1) Net of taxes (5) (2) (7) (1) Net changes in benefit plan assets and obligations 20 14 64 40 Income tax expense 4 3 13 8 Net of taxes 16 11 51 32 Net changes in unrealized foreign currency translation 79 (75) (137) (20) Income tax expense (benefit) 5 (7) (18) (5) Net of taxes 74 (68) (119) (15) Total other comprehensive income 309 541 1,918 3,147 Total income tax expense 53 122 420 663 Total other comprehensive income, net of taxes $ 256 $ 419 $ 1,498 $ 2,484 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. Three Months Ended Nine Months Ended (in millions) 2020 2019 2020 2019 Reclassification adjustments related to unrealized gains on investment securities: Having no credit losses recognized in the consolidated statement of income (1) $ (23) $ (14) $ (31) $ (43) Income tax expense (2) (5) (3) (7) (9) Net of taxes (18) (11) (24) (34) Having credit losses recognized in the consolidated statement of income (1) — — — — Income tax benefit (2) — — — — Net of taxes — — — — Reclassification adjustment related to benefit plan assets and obligations: Claims and claim adjustment expenses (3) 8 4 26 15 General and administrative expenses (3) 12 8 37 23 Total 20 12 63 38 Income tax benefit (2) 4 3 13 8 Net of taxes 16 9 50 30 Reclassification adjustment related to foreign currency translation (1) — — — — Income tax benefit (2) — — — — Net of taxes — — — — Total reclassifications (3) (2) 32 (5) Total income tax (expense) benefit (1) — 6 (1) Total reclassifications, net of taxes $ (2) $ (2) $ 26 $ (4) _________________________________________________________ (1) (Increases) decreases net realized investment gains (losses) 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.

Debt

Debt	9 Months Ended
	Sep. 30, 2020
Debt Disclosure [Abstract]
Debt	DEBT Debt Issuance . On April 27, 2020, the Company issued $500 million aggregate principal amount of 2.55% senior notes that will mature on April 27, 2050. The net proceeds of the issuance, after the deduction of the underwriting discount and expenses payable by the Company, totaled approximately $490 million. Interest on the senior notes is payable semi-annually in arrears on April 27 and October 27. Prior to October 27, 2049, 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 October 27, 2049 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 25 basis points. On or after October 27, 2049, 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.

Common Share Repurchases

Common Share Repurchases	9 Months Ended
	Sep. 30, 2020
Treasury Stock Transactions, Excluding Value of Shares Reissued [Abstract]
Common Share Repurchases	COMMON SHARE REPURCHASES During the three months ended September 30, 2020, the Company did not repurchase any common shares under its share repurchase authorization. For the nine months ended September 30, 2020, the Company repurchased 3.5 million shares under its share repurchase authorization, for a total cost of $425 million, all of which were repurchased during the three months ended March 31, 2020. The average cost per share repurchased was $123.09. In addition, the Company acquired 1,368 shares and 0.3 million shares for a total cost of approximately $159,000 and $46 million during the three months and nine months ended September 30, 2020, respectively, that were not part of the publicly announced share repurchase authorization. These shares consisted of shares retained 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. At September 30, 2020, the Company had $1.36 billion of capacity remaining under its share repurchase authorization.

Earnings per Share

Earnings per Share	9 Months Ended
	Sep. 30, 2020
Earnings Per Share Reconciliation [Abstract]
Earnings per Share	EARNINGS PER SHARE The following is a reconciliation of the income and share data used in the basic and diluted earnings per share computations for the periods presented: Three Months Ended Nine Months Ended (in millions, except per share amounts) 2020 2019 2020 2019 Basic and Diluted Net income, as reported $ 827 $ 396 $ 1,387 $ 1,749 Participating share-based awards — allocated income (6) (3) (9) (12) Net income available to common shareholders — basic and diluted $ 821 $ 393 $ 1,378 $ 1,737 Common Shares Basic Weighted average shares outstanding 253.3 259.2 253.5 261.1 Diluted Weighted average shares outstanding 253.3 259.2 253.5 261.1 Weighted average effects of dilutive securities — stock options and performance shares 1.0 2.6 1.0 2.3 Total 254.3 261.8 254.5 263.4 Net Income per Common Share Basic $ 3.24 $ 1.52 $ 5.44 $ 6.65 Diluted $ 3.23 $ 1.50 $ 5.41 $ 6.59

Share-Based Incentive Compensat

Share-Based Incentive Compensation	9 Months Ended
	Sep. 30, 2020
Share-based Payment Arrangement [Abstract]
Share-Based Incentive Compensation	SHARE-BASED INCENTIVE COMPENSATION The following information relates to fully vested stock option awards at September 30, 2020: Stock Options Number Weighted Weighted Aggregate Vested at end of period (1) 7,474,888 $ 114.76 5.5 years $ 36 Exercisable at end of period 5,210,232 $ 107.04 4.2 years $ 36 _________________________________________________________ (1) Represents awards for which the requisite service has been rendered, including those that are retirement eligible. The total compensation cost for all share-based incentive compensation awards recognized in earnings was $33 million and $32 million for the three months ended September 30, 2020 and 2019, respectively, and $113 million and $112 million for the nine months ended September 30, 2020 and 2019, respectively. The related tax benefits recognized in the consolidated statement of income were $6 million for each of the three months ended September 30, 2020 and 2019, and $20 million for each of the nine months ended September 30, 2020 and 2019. The total unrecognized compensation cost related to all nonvested share-based incentive compensation awards at September 30, 2020 was $165 million, which is expected to be recognized over a weighted-average period of 1.8 years.

Pension Plans, Retirement Benef

Pension Plans, Retirement Benefits and Savings Plans	9 Months Ended
	Sep. 30, 2020
Retirement Benefits [Abstract]
Pension Plans, Retirement Benefits and Savings Plans	PENSION PLANS, RETIREMENT BENEFITS AND SAVINGS PLANS The following table summarizes the components of net periodic benefit cost (benefit) for the Company’s pension and postretirement benefit plans recognized in the consolidated statement of income for the three months ended September 30, 2020 and 2019. Pension Plans Postretirement Benefit Plans (for the three months ended September 30, in millions) 2020 2019 2020 2019 Net Periodic Benefit Cost: Service cost $ 34 $ 30 $ — $ — Non-service cost (benefit): Interest cost on benefit obligation $ 29 $ 35 $ 1 $ 2 Expected return on plan assets (69) (69) — — Amortization of unrecognized: Prior service benefit (1) — (1) (1) Net actuarial (gain) loss 23 14 (1) — Total non-service cost (benefit) (18) (20) (1) 1 Net periodic benefit cost (benefit) $ 16 $ 10 $ (1) $ 1 The following table indicates the line items in which the respective service cost and non-service cost (benefit) are presented in the consolidated statement of income for the three months ended September 30, 2020 and 2019. Pension Plans Postretirement Benefit Plans (for the three months ended September 30, in millions) 2020 2019 2020 2019 Service Cost: Claims and claim adjustment expenses $ 14 $ 13 $ — $ — General and administrative expenses 20 17 — — Total service cost 34 30 — — Non-Service Cost (Benefit): Claims and claim adjustment expenses (8) (9) (1) — General and administrative expenses (10) (11) — 1 Total non-service cost (benefit) (18) (20) (1) 1 Net periodic benefit cost (benefit) $ 16 $ 10 $ (1) $ 1 The following table summarizes the components of net periodic benefit cost (benefit) for the Company’s pension and postretirement benefit plans recognized in the consolidated statement of income for the nine months ended September 30, 2020 and 2019. Pension Plans Postretirement Benefit Plans (for the nine months ended September 30, in millions) 2020 2019 2020 2019 Net Periodic Benefit Cost: Service cost $ 100 $ 89 $ — $ — Non-service cost (benefit): Interest cost on benefit obligation 86 105 3 6 Expected return on plan assets (206) (206) — — Amortization of unrecognized: Prior service benefit (1) (1) (3) (3) Net actuarial (gain) loss 69 42 (2) — Total non-service cost (benefit) (52) (60) (2) 3 Net periodic benefit cost (benefit) $ 48 $ 29 $ (2) $ 3 The following table indicates the line items in which the respective service cost and non-service benefit cost (benefit) are presented in the consolidated statement of income for the nine months ended September 30, 2020 and 2019. Pension Plans Postretirement Benefit Plans (for the nine months ended September 30, in millions) 2020 2019 2020 2019 Service Cost: Claims and claim adjustment expenses $ 42 $ 37 $ — $ — General and administrative expenses 58 52 — — Total service cost 100 89 — — Non-Service Cost (Benefit): Claims and claim adjustment expenses (22) (25) (1) 1 General and administrative expenses (30) (35) (1) 2 Total non-service cost (benefit) (52) (60) (2) 3 Net periodic benefit cost (benefit) $ 48 $ 29 $ (2) $ 3

Leases

Leases	9 Months Ended
	Sep. 30, 2020
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, and a right-of-use asset and lease liability is recognized as part of other assets and other liabilities, respectively, in the consolidated balance sheet. 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: Three Months Ended Nine Months Ended (in millions) 2020 2019 2020 2019 Lease cost Operating leases $ 23 $ 23 $ 71 $ 68 Short-term leases (1) 1 2 2 9 Lease expense 24 25 73 77 Less: sublease income (2) — — — — Net lease cost $ 24 $ 25 $ 73 $ 77 Other information on operating leases Cash payments to settle a lease liability reported in cash flows $ 27 $ 27 $ 82 $ 77 Right-of-use assets obtained in exchange for new lease liabilities $ 8 $ 14 $ 26 $ 50 Weighted average discount rate 2.86 % 3.04 % 2.86 % 3.04 % Weighted average remaining lease term 4.9 years 5.2 years 4.9 years 5.2 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. The following table presents the contractual maturities of the Company's lease liabilities: (in millions) Real Estate Lease Liability Remainder of 2020 $ 27 2021 100 2022 76 2023 56 2024 40 Thereafter 63 Total undiscounted lease payments 362 Less: present value adjustment 25 Operating lease liability $ 337

Contingencies, Commitments and

Contingencies, Commitments and Guarantees	9 Months Ended
	Sep. 30, 2020
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 $1.65 billion and $1.66 billion at September 30, 2020 and December 31, 2019, respectively. Guarantees The maximum amount of the Company’s contingent obligation for indemnifications related to the sale of businesses that are quantifiable was $351 million at September 30, 2020. 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 September 30, 2020, all of which is indemnified by a third party. For more information regarding Company guarantees, see note 16 of notes to the consolidated financial statements in the Company’s 2019 Annual Report.

Basis of Presentation and Acc_2

Basis of Presentation and Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation [Policy Text Block]	Basis of Presentation The interim consolidated financial statements include the accounts of The Travelers Companies, Inc. (together with its subsidiaries, the Company). These financial statements are prepared in conformity with U.S. generally accepted accounting principles (GAAP) and are unaudited. In the opinion of the Company’s management, all adjustments necessary for a fair presentation have been reflected. Certain financial information that is normally included in annual financial statements prepared in accordance with GAAP, but that is not required for interim reporting purposes, has been omitted. All material intercompany transactions and balances have been eliminated. The accompanying interim consolidated financial statements and related notes should be read in conjunction with the Company’s consolidated financial statements and related notes included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2019 (the Company’s 2019 Annual Report). The preparation of the interim consolidated financial statements in conformity with 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 interim consolidated financial statements and the reported amounts of revenues and claims and expenses during the reporting period. Actual results could differ from those estimates. Certain reclassifications have been made to the 2019 financial statements to conform to the 2020 presentation.
Adoption of Accounting Standards [Policy Text Block]	Adoption of Accounting Standards Registered Debt Offerings that Include Credit Enhancements from an Affiliate In March 2020, the Securities and Exchange Commission (SEC) adopted amendments to the financial disclosure requirements related to certain debt securities, including registered debt securities issued by a wholly-owned, operating subsidiary that are fully and unconditionally guaranteed by the parent company. Prior to the amendments, a parent guarantor was required to provide condensed consolidating financial information for so long as the guaranteed securities were outstanding, regardless of whether the subsidiary issuer could have suspended its public reporting obligations under the applicable SEC requirements with respect to the securities. In accordance with the amended requirements, a parent guarantor may cease providing the condensed consolidating financial information if the corresponding subsidiary issuer’s public reporting obligation is suspended. The amendments to the financial disclosure requirements are effective on January 4, 2021; however, the SEC permits voluntary compliance in advance of the effective date. The Company elected to apply the amended requirements beginning with the quarter ended March 31, 2020, and is no longer providing condensed consolidating financial information that resulted from the registered debt obligations of its subsidiaries, Travelers Property Casualty Corp. and Travelers Insurance Group Holdings Inc., that were disclosed in note 8 of the financial statements in the Company’s 2019 Annual Report . Financial Instruments - Credit Losses: Measurement of Credit Losses on Financial Instruments In June 2016, the Financial Accounting Standards Board 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 previous 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 Company adopted the updated guidance for the quarter ended March 31, 2020. For additional information regarding accounting standards that the Company adopted during the periods presented, see note 1 of notes to the consolidated financial statements in the Company’s 2019 Annual Report.
Investment Impairments [Policy Text Block]	Investment Impairments The Company conducts a periodic review to identify and evaluate invested assets that may have credit impairments. Credit Impairments of Fixed Maturity Investments Some of the factors considered in assessing impairment of fixed maturity investments due to credit-related factors 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; and (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. Beginning on January 1, 2020, credit losses are recognized through an allowance account. See note 1 - Adoption of Accounting Standards - Financial Instruments - Credit Losses: Measurement of Credit Losses on Financial Instruments for additional information. 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 (non-credit factors) is reported in other comprehensive income. The allowance is adjusted for any additional credit losses and subsequent recoveries. Upon recognizing a credit loss, the cost basis is not adjusted. For fixed maturity investments where the Company records a credit loss, a determination is made as to the cause of the impairment and whether the Company expects a recovery in the value. For fixed maturity investments where the Company expects a recovery in value, the constant effective yield method is utilized, and the investment is amortized to par. 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). The new cost basis of the investment is the previous amortized cost basis less the impairment recognized in net realized investment gains (losses). The new cost basis is not adjusted for any subsequent recoveries in fair value. The Company reports investment income accrued separately from fixed maturity investments, available for sale, and has elected not to measure an allowance for credit losses for investment income accrued. Investment income accrued is written off through net realized investment gains (losses) at the time the issuer of the bond defaults or is expected to default on payments. Uncollectible available-for-sale debt securities are written-off when the Company determines that no additional payments of principal or interest will be received.
Reinsurance Recoverables [Policy Text Block]	Reinsurance Recoverables Amounts recoverable from reinsurers are estimated in a manner consistent with the associated claim liability. Included in reinsurance recoverables are amounts related to certain structured settlements. The Company reports its reinsurance recoverables net of an allowance for estimated uncollectible reinsurance. 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. For structured settlements, the allowance is also based upon the Company’s ongoing review of life insurers’ creditworthiness and estimated amounts of coverage that would be available from state guaranty funds if a life insurer defaults. A probability-of-default methodology which reflects current and forecasted economic conditions is used to estimate the amount of uncollectible reinsurance due to credit-related factors and the estimate is reported in an allowance for estimated uncollectible reinsurance. The allowance also includes estimated uncollectible amounts related to dispute risk with reinsurers. Amounts deemed to be uncollectible, including amounts due from known insolvent reinsurers, are written off against the allowance. Changes in the allowance, as well as 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.
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 both contractholder payables and contractholder receivables. Contractholder receivables are reported net of an allowance for expected credit losses. The allowance is based upon the Company’s ongoing review of amounts outstanding, changes in policyholder credit standing, and other relevant factors. A probability-of-default methodology which reflects current and forecasted economic conditions is used to estimate the allowance for expected credit losses.
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 expected credit losses. The allowance is based upon the Company’s ongoing review of amounts outstanding, historical loss data, including delinquencies and write-offs, current and forecasted economic conditions and other relevant factors. Credit risk is partially mitigated by the Company’s ability to cancel the policy if the policyholder does not pay the premium.

Segment Information (Tables)

Segment Information (Tables)	9 Months Ended
	Sep. 30, 2020
Segment Reporting [Abstract]
Company's revenues and income by segment [Table Text Block]	(For the three months ended September 30, in millions) Business Bond & Specialty Personal Total 2020 Premiums $ 3,841 $ 723 $ 2,816 $ 7,380 Net investment income 498 58 115 671 Fee income 95 — 6 101 Other revenues 58 7 21 86 Total segment revenues (1) $ 4,492 $ 788 $ 2,958 $ 8,238 Segment income (1) $ 365 $ 115 $ 392 $ 872 2019 Premiums $ 3,882 $ 653 $ 2,644 $ 7,179 Net investment income 457 59 106 622 Fee income 114 — 7 121 Other revenues 39 7 22 68 Total segment revenues (1) $ 4,492 $ 719 $ 2,779 $ 7,990 Segment income (1) $ 179 $ 139 $ 131 $ 449 _________________________________________________________ (1) Segment revenues for reportable business segments exclude net realized investment gains (losses) and revenues included in "interest expense and other." Segment income for reportable business segments equals net income excluding the after-tax impact of net realized investment gains (losses) and income (loss) from "interest expense and other." (For the nine months ended September 30, in millions) Business Bond & Specialty Personal Total 2020 Premiums $ 11,440 $ 2,083 $ 8,041 $ 21,564 Net investment income 1,131 155 264 1,550 Fee income 305 — 18 323 Other revenues 125 17 53 195 Total segment revenues (1) $ 13,001 $ 2,255 $ 8,376 $ 23,632 Segment income (1) $ 596 $ 309 $ 738 $ 1,643 2019 Premiums $ 11,407 $ 1,891 $ 7,724 $ 21,022 Net investment income 1,365 173 314 1,852 Fee income 329 — 17 346 Other revenues 112 19 65 196 Total segment revenues (1) $ 13,213 $ 2,083 $ 8,120 $ 23,416 Segment income (1) $ 944 $ 451 $ 497 $ 1,892 _________________________________________________________ (1) Segment revenues for reportable business segments exclude net realized investment gains (losses) and revenues included in "interest expense and other." Segment income for reportable business segments equals net income excluding the after-tax impact of net realized investment gains (losses) and income (loss) from "interest expense and other."
Business segment reconciliations of revenue and income, net of tax [Table Text Block]	Business Segment Reconciliations Three Months Ended Nine Months Ended (in millions) 2020 2019 2020 2019 Revenue reconciliation Earned premiums Business Insurance: Domestic: Workers’ compensation $ 851 $ 969 $ 2,568 $ 2,891 Commercial automobile 698 672 2,058 1,947 Commercial property 522 496 1,544 1,429 General liability 605 594 1,786 1,746 Commercial multi-peril 891 872 2,660 2,568 Other 15 12 38 29 Total Domestic 3,582 3,615 10,654 10,610 International 259 267 786 797 Total Business Insurance 3,841 3,882 11,440 11,407 Bond & Specialty Insurance: Domestic: Fidelity and surety 277 265 805 769 General liability 310 276 893 799 Other 60 54 178 159 Total Domestic 647 595 1,876 1,727 International 76 58 207 164 Total Bond & Specialty Insurance 723 653 2,083 1,891 Personal Insurance: Domestic: Automobile 1,391 1,344 3,896 3,962 Homeowners and Other 1,262 1,119 3,659 3,236 Total Domestic 2,653 2,463 7,555 7,198 International 163 181 486 526 Total Personal Insurance 2,816 2,644 8,041 7,724 Total earned premiums 7,380 7,179 21,564 21,022 Net investment income 671 622 1,550 1,852 Fee income 101 121 323 346 Other revenues 86 68 195 196 Total segment revenues 8,238 7,990 23,632 23,416 Other revenues — — — 1 Net realized investment gains (losses) 37 23 (48) 101 Total revenues $ 8,275 $ 8,013 $ 23,584 $ 23,518 Income reconciliation, net of tax Total segment income $ 872 $ 449 $ 1,643 $ 1,892 Interest Expense and Other (1) (74) (71) (219) (222) Core income 798 378 1,424 1,670 Net realized investment gains (losses) 29 18 (37) 79 Net income $ 827 $ 396 $ 1,387 $ 1,749 _________________________________________________________ (1) The primary component of Interest Expense and Other was after-tax interest expense of $69 million and $66 million for the three months ended September 30, 2020 and 2019, respectively, and $202 million and $206 million for the nine months ended September 30, 2020 and 2019, respectively.
Asset reconciliation [Table Text Block]	(in millions) September 30, December 31, Asset reconciliation Business Insurance $ 88,040 $ 83,896 Bond & Specialty Insurance 9,483 8,599 Personal Insurance 18,230 17,015 Total assets by reportable segment 115,753 109,510 Other assets (1) 631 612 Total consolidated assets $ 116,384 $ 110,122 _________________________________________________________ (1) The primary components of other assets at both September 30, 2020 and December 31, 2019 were accrued over-funded benefit plan assets related to the Company’s qualified domestic pension plan and other intangible assets.

Investments (Tables)

Investments (Tables)	9 Months Ended
	Sep. 30, 2020
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 Cost Allowance for Expected Credit Losses Gross Unrealized Fair Value (at September 30, 2020, in millions) Gains Losses U.S. Treasury securities and obligations of U.S. government and government agencies and authorities $ 2,083 $ — $ 43 $ — $ 2,126 Obligations of states, municipalities and political subdivisions: Local general obligation 17,019 — 1,267 8 18,278 Revenue 11,871 — 829 6 12,694 State general obligation 1,160 — 91 — 1,251 Pre-refunded 2,458 — 160 — 2,618 Total obligations of states, municipalities and political subdivisions 32,508 — 2,347 14 34,841 Debt securities issued by foreign governments 952 — 27 — 979 Mortgage-backed securities, collateralized mortgage obligations and pass-through securities 2,572 — 158 — 2,730 All other corporate bonds 29,599 4 2,314 35 31,874 Redeemable preferred stock 22 — 2 — 24 Total $ 67,736 $ 4 $ 4,891 $ 49 $ 72,574 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
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: Fair (at September 30, 2020, in millions) Cost Gross Gains Gross Losses Value Public common stock $ 346 $ 44 $ 22 $ 368 Non-redeemable preferred stock 35 8 1 42 Total $ 381 $ 52 $ 23 $ 410 Fair (at December 31, 2019, in millions) Cost Gross Gains Gross Losses Value Public common stock $ 341 $ 45 $ 3 $ 383 Non-redeemable preferred stock 35 7 — 42 Total $ 376 $ 52 $ 3 $ 425
Unrealized investment losses [Table Text Block]	The following tables summarize, for all investments in an unrealized loss position at September 30, 2020 and December 31, 2019, 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 herein and in note 4 of notes to the consolidated financial statements in the Company’s 2019 Annual Report. The Company also relies upon estimates of several credit and non-credit factors in its review and evaluation of individual investments, using the process described in note 1 of notes to the consolidated financial statements to determine whether credit impairment exists. Less than 12 months 12 months or longer Total (at September 30, 2020, in millions) Fair Gross Fair Gross Fair Gross Fixed maturities U.S. Treasury securities and obligations of U.S. government and government agencies and authorities $ 169 $ — $ — $ — $ 169 $ — Obligations of states, municipalities and political subdivisions 1,751 14 — — 1,751 14 Debt securities issued by foreign governments 14 — — — 14 — Mortgage-backed securities, collateralized mortgage obligations and pass-through securities 11 — 1 — 12 — All other corporate bonds 1,095 28 120 7 1,215 35 Total $ 3,040 $ 42 $ 121 $ 7 $ 3,161 $ 49 Less than 12 months 12 months or longer Total (at December 31, 2019, in millions) Fair Gross Fair Gross Fair Gross 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 $ 2,900 $ 19 $ 1,145 $ 10 $ 4,045 $ 29
Changes in the allowance for expected credit losses on fixed maturities classified as available for sale [Table Text Block]	The following tables present changes in the allowance for expected credit losses on fixed maturities classified as available for sale: Fixed Maturities (for the three months ended September 30, 2020 in millions) Mortgage-Backed Securities, Collateralized Mortgage Obligations and Pass-Through Securities All Other Corporate Bonds Total Balance, July 1, 2020 $ — $ 8 $ 8 Additions for expected credit losses on securities where no credit losses were previously recognized — 1 1 Additions (reductions) for expected credit losses on securities where credit losses were previously recognized — (3) (3) Reductions due to sales/defaults of credit-impaired securities — (2) (2) Reductions for impairments of securities which the Company intends to sell or more likely than not will be required to sell (1) — — — Balance, September 30, 2020 $ — $ 4 $ 4 Fixed Maturities (for the nine months ended September 30, 2020 in millions) Mortgage-Backed Securities, Collateralized Mortgage Obligations and Pass-Through Securities All Other Corporate Bonds Total Balance, January 1, 2020 $ — $ — $ — Additions for expected credit losses on securities where no credit losses were previously recognized — 9 9 Additions (reductions) for expected credit losses on securities where credit losses were previously recognized — (3) (3) Reductions due to sales/defaults of credit-impaired securities — (2) (2) Reductions for impairments of securities which the Company intends to sell or more likely than not will be required to sell (1) — — — Balance, September 30, 2020 $ — $ 4 $ 4 _________________________________________________________ (1) Credit impairment charges recognized in net realized investment gains (losses) for the nine months ended September 30, 2020 included $14 million of credit losses on fixed maturity securities which the Company intends to sell. An allowance for expected credit losses was not previously recorded for these securities.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2020
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 September 30, 2020, 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 $ 2,126 $ 2,126 $ — $ — Obligations of states, municipalities and political subdivisions 34,841 — 34,830 11 Debt securities issued by foreign governments 979 — 979 — Mortgage-backed securities, collateralized mortgage obligations and pass-through securities 2,730 — 2,730 — All other corporate bonds 31,874 6 31,787 81 Redeemable preferred stock 24 — 24 — Total fixed maturities 72,574 2,132 70,350 92 Equity securities Public common stock 368 368 — — Non-redeemable preferred stock 42 21 21 — Total equity securities 410 389 21 — Other investments 48 14 — 34 Total $ 73,032 $ 2,535 $ 70,371 $ 126 Other liabilities $ 7 $ — $ — $ 7 (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
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 September 30, 2020, in millions) Carrying Fair Level 1 Level 2 Level 3 Financial assets Short-term securities $ 6,329 $ 6,329 $ 977 $ 5,307 $ 45 Financial liabilities Debt $ 6,950 $ 9,083 $ — $ 9,083 $ — Commercial paper $ 100 $ 100 $ — $ 100 $ — (at December 31, 2019, in millions) Carrying Fair 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 $ —

Allowance for Expected Credit_2

Allowance for Expected Credit Losses (Tables)	9 Months Ended
	Sep. 30, 2020
Credit Loss [Abstract]
Changes in the allowance for expected credit losses on premiums receivable [Table Text Block]	The following tables present the balances of premiums receivable, net of the allowance for expected credit losses, at September 30, 2020 and January 1, 2020, and the changes in the allowance for expected credit losses for the three months and nine months ended September 30, 2020. At and For the Three Months Ended September 30, 2020 At and For the Nine Months Ended September 30, 2020 (in millions) Premiums Receivable, Net of Allowance for Expected Credit Losses Allowance for Expected Credit Losses Premiums Receivable, Net of Allowance for Expected Credit Losses Allowance for Expected Credit Losses Balance, beginning of period $ 8,459 $ 94 $ 7,909 $ 49 Current period change for expected credit losses 17 84 Write-offs of uncollectible premiums receivable 15 37 Balance, end of period $ 8,225 $ 96 $ 8,225 $ 96
Changes in the allowance for estimated uncollectible reinsurance [Table Text Block]	The following tables present the balances of reinsurance recoverables, net of the allowance for estimated uncollectible reinsurance, at September 30, 2020 and January 1, 2020, and the changes in the allowance for estimated uncollectible reinsurance for the three months and nine months ended September 30, 2020. At and For the Three Months Ended September 30, 2020 At and For the Nine Months Ended September 30, 2020 (in millions) Reinsurance Recoverables, Net of Allowance for Estimated Uncollectible Reinsurance Allowance for Estimated Uncollectible Reinsurance Reinsurance Recoverables, Net of Allowance for Estimated Uncollectible Reinsurance Allowance for Estimated Uncollectible Reinsurance Balance, beginning of period $ 8,093 $ 156 $ 8,235 $ 92 Cumulative effect of adoption of updated accounting guidance for credit losses at January 1, 2020 — 53 Current period change for estimated uncollectible reinsurance (16) (5) Write-offs of uncollectible reinsurance recoverables — — Balance, end of period $ 8,317 $ 140 $ 8,317 $ 140
Changes in the allowance for expected credit losses on contractholder receivables [Table Text Block]	The following tables present the balances of contractholder receivables, net of the allowance for expected credit losses, at September 30, 2020 and January 1, 2020, and the changes in the allowance for expected credit losses for the three months and nine months ended September 30, 2020. At and For the Three Months Ended September 30, 2020 At and For the Nine Months Ended September 30, 2020 (in millions) Contractholder Receivables, Net of Allowance for Expected Credit Losses Allowance for Expected Credit Losses Contractholder Receivables, Net of Allowance for Expected Credit Losses Allowance for Expected Credit Losses Balance, beginning of period $ 4,314 $ 22 $ 4,599 $ 20 Current period change for expected credit losses — 2 Write-offs of uncollectible contractholder receivables 1 1 Balance, end of period $ 4,347 $ 21 $ 4,347 $ 21

Goodwill and Other Intangible_2

Goodwill and Other Intangible Assets (Tables)	9 Months Ended
	Sep. 30, 2020
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. (in millions) September 30, December 31, Business Insurance $ 2,589 $ 2,601 Bond & Specialty Insurance 550 550 Personal Insurance 780 784 Other 26 26 Total $ 3,945 $ 3,961
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 September 30, 2020, in millions) Gross Accumulated Net Subject to amortization Customer-related $ 98 $ 28 $ 70 Contract-based (1) 204 182 22 Total subject to amortization 302 210 92 Not subject to amortization 226 — 226 Total $ 528 $ 210 $ 318 (at December 31, 2019, in millions) Gross Accumulated 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 _________________________________________________________ (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 September 30, 2020, in millions) Gross Accumulated Net Subject to amortization Customer-related $ 98 $ 28 $ 70 Contract-based (1) 204 182 22 Total subject to amortization 302 210 92 Not subject to amortization 226 — 226 Total $ 528 $ 210 $ 318 (at December 31, 2019, in millions) Gross Accumulated 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 _________________________________________________________ (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)	9 Months Ended
	Sep. 30, 2020
Insurance Loss Reserves [Abstract]
Claims and claim adjustment expense reserves [Table Text Block]	Claims and claim adjustment expense reserves were as follows: (in millions) September 30, December 31, Property-casualty $ 54,406 $ 51,836 Accident and health 12 13 Total $ 54,418 $ 51,849
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: Nine Months Ended September 30, (in millions) 2020 2019 Claims and claim adjustment expense reserves at beginning of year $ 51,836 $ 50,653 Less reinsurance recoverables on unpaid losses 8,035 8,182 Cumulative effect of adoption of updated accounting guidance for credit losses at January 1, 2020 53 — Net reserves at beginning of year 43,854 42,471 Estimated claims and claim adjustment expenses for claims arising in the current year 14,809 14,193 Estimated increase (decrease) in claims and claim adjustment expenses for claims arising in prior years (108) 214 Total increases 14,701 14,407 Claims and claim adjustment expense payments for claims arising in: Current year 4,960 5,174 Prior years 7,246 8,034 Total payments 12,206 13,208 Unrealized foreign exchange (gain) loss (62) 12 Net reserves at end of period 46,287 43,682 Plus reinsurance recoverables on unpaid losses 8,119 7,916 Claims and claim adjustment expense reserves at end of period $ 54,406 $ 51,598

Other Comprehensive Income an_2

Other Comprehensive Income and Accumulated Other Comprehensive Income (Tables)	9 Months Ended
	Sep. 30, 2020
Other Comprehensive Income And Accumulated Other Comprehensive Income Disclosure [Abstract]
Changes in accumulated other comprehensive income (loss) (AOCI) [Table Text Block]	The following tables present the changes in the Company’s accumulated other comprehensive income (loss) (AOCI) for the three months and nine months ended September 30, 2020. Changes in Net Unrealized Gains on Investment Securities (in millions) Having No Credit Having Credit Net Benefit Plan Assets and Net Unrealized Total Accumulated Balance, June 30, 2020 $ 3,459 $ 187 $ (811) $ (953) $ 1,882 Other comprehensive income (loss) (OCI) before reclassifications, net of tax 189 (5) — 74 258 Amounts reclassified from AOCI, net of tax (18) — 16 — (2) Net OCI, current period 171 (5) 16 74 256 Balance, September 30, 2020 $ 3,630 $ 182 $ (795) $ (879) $ 2,138 Changes in Net Unrealized Gains on Investment Securities (in millions) Having No Credit Losses Recognized in the Consolidated Statement of Income Having Credit Net Benefit Plan Assets and Obligations Recognized in Shareholders’ Equity Net Unrealized Foreign Currency Translation Total Accumulated Other Comprehensive Income Balance, December 31, 2019 $ 2,057 $ 189 $ (846) $ (760) $ 640 Other comprehensive income (loss) (OCI) before reclassifications, net of tax 1,597 (7) 1 (119) 1,472 Amounts reclassified from AOCI, net of tax (24) — 50 — 26 Net OCI, current period 1,573 (7) 51 (119) 1,498 Balance, September 30, 2020 $ 3,630 $ 182 $ (795) $ (879) $ 2,138
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 and the related income tax expense. Three Months Ended Nine Months Ended (in millions) 2020 2019 2020 2019 Changes in net unrealized gains on investment securities: Having no credit losses recognized in the consolidated statement of income $ 217 $ 605 $ 2,001 $ 3,129 Income tax expense 46 127 428 661 Net of taxes 171 478 1,573 2,468 Having credit losses recognized in the consolidated statement of income (7) (3) (10) (2) Income tax benefit (2) (1) (3) (1) Net of taxes (5) (2) (7) (1) Net changes in benefit plan assets and obligations 20 14 64 40 Income tax expense 4 3 13 8 Net of taxes 16 11 51 32 Net changes in unrealized foreign currency translation 79 (75) (137) (20) Income tax expense (benefit) 5 (7) (18) (5) Net of taxes 74 (68) (119) (15) Total other comprehensive income 309 541 1,918 3,147 Total income tax expense 53 122 420 663 Total other comprehensive income, net of taxes $ 256 $ 419 $ 1,498 $ 2,484
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. Three Months Ended Nine Months Ended (in millions) 2020 2019 2020 2019 Reclassification adjustments related to unrealized gains on investment securities: Having no credit losses recognized in the consolidated statement of income (1) $ (23) $ (14) $ (31) $ (43) Income tax expense (2) (5) (3) (7) (9) Net of taxes (18) (11) (24) (34) Having credit losses recognized in the consolidated statement of income (1) — — — — Income tax benefit (2) — — — — Net of taxes — — — — Reclassification adjustment related to benefit plan assets and obligations: Claims and claim adjustment expenses (3) 8 4 26 15 General and administrative expenses (3) 12 8 37 23 Total 20 12 63 38 Income tax benefit (2) 4 3 13 8 Net of taxes 16 9 50 30 Reclassification adjustment related to foreign currency translation (1) — — — — Income tax benefit (2) — — — — Net of taxes — — — — Total reclassifications (3) (2) 32 (5) Total income tax (expense) benefit (1) — 6 (1) Total reclassifications, net of taxes $ (2) $ (2) $ 26 $ (4) _________________________________________________________ (1) (Increases) decreases net realized investment gains (losses) 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)	9 Months Ended
	Sep. 30, 2020
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 periods presented: Three Months Ended Nine Months Ended (in millions, except per share amounts) 2020 2019 2020 2019 Basic and Diluted Net income, as reported $ 827 $ 396 $ 1,387 $ 1,749 Participating share-based awards — allocated income (6) (3) (9) (12) Net income available to common shareholders — basic and diluted $ 821 $ 393 $ 1,378 $ 1,737 Common Shares Basic Weighted average shares outstanding 253.3 259.2 253.5 261.1 Diluted Weighted average shares outstanding 253.3 259.2 253.5 261.1 Weighted average effects of dilutive securities — stock options and performance shares 1.0 2.6 1.0 2.3 Total 254.3 261.8 254.5 263.4 Net Income per Common Share Basic $ 3.24 $ 1.52 $ 5.44 $ 6.65 Diluted $ 3.23 $ 1.50 $ 5.41 $ 6.59

Share-Based Incentive Compens_2

Share-Based Incentive Compensation (Table)	9 Months Ended
	Sep. 30, 2020
Share-based Payment Arrangement [Abstract]
Information for fully vested stock option awards [Table Text Block]	The following information relates to fully vested stock option awards at September 30, 2020: Stock Options Number Weighted Weighted Aggregate Vested at end of period (1) 7,474,888 $ 114.76 5.5 years $ 36 Exercisable at end of period 5,210,232 $ 107.04 4.2 years $ 36 _________________________________________________________ (1) Represents awards for which the requisite service has been rendered, including those that are retirement eligible.

Pension Plans, Retirement Ben_2

Pension Plans, Retirement Benefits and Savings Plans (Tables)	9 Months Ended
	Sep. 30, 2020
Retirement Benefits [Abstract]
Summary of the components of net periodic benefit cost for the Company's pension and postretirement benefit plans recognized in the consolidated statement of income [Table Text Block]	The following table summarizes the components of net periodic benefit cost (benefit) for the Company’s pension and postretirement benefit plans recognized in the consolidated statement of income for the three months ended September 30, 2020 and 2019. Pension Plans Postretirement Benefit Plans (for the three months ended September 30, in millions) 2020 2019 2020 2019 Net Periodic Benefit Cost: Service cost $ 34 $ 30 $ — $ — Non-service cost (benefit): Interest cost on benefit obligation $ 29 $ 35 $ 1 $ 2 Expected return on plan assets (69) (69) — — Amortization of unrecognized: Prior service benefit (1) — (1) (1) Net actuarial (gain) loss 23 14 (1) — Total non-service cost (benefit) (18) (20) (1) 1 Net periodic benefit cost (benefit) $ 16 $ 10 $ (1) $ 1 The following table summarizes the components of net periodic benefit cost (benefit) for the Company’s pension and postretirement benefit plans recognized in the consolidated statement of income for the nine months ended September 30, 2020 and 2019. Pension Plans Postretirement Benefit Plans (for the nine months ended September 30, in millions) 2020 2019 2020 2019 Net Periodic Benefit Cost: Service cost $ 100 $ 89 $ — $ — Non-service cost (benefit): Interest cost on benefit obligation 86 105 3 6 Expected return on plan assets (206) (206) — — Amortization of unrecognized: Prior service benefit (1) (1) (3) (3) Net actuarial (gain) loss 69 42 (2) — Total non-service cost (benefit) (52) (60) (2) 3 Net periodic benefit cost (benefit) $ 48 $ 29 $ (2) $ 3
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 cost and non-service cost (benefit) are presented in the consolidated statement of income for the three months ended September 30, 2020 and 2019. Pension Plans Postretirement Benefit Plans (for the three months ended September 30, in millions) 2020 2019 2020 2019 Service Cost: Claims and claim adjustment expenses $ 14 $ 13 $ — $ — General and administrative expenses 20 17 — — Total service cost 34 30 — — Non-Service Cost (Benefit): Claims and claim adjustment expenses (8) (9) (1) — General and administrative expenses (10) (11) — 1 Total non-service cost (benefit) (18) (20) (1) 1 Net periodic benefit cost (benefit) $ 16 $ 10 $ (1) $ 1 The following table indicates the line items in which the respective service cost and non-service benefit cost (benefit) are presented in the consolidated statement of income for the nine months ended September 30, 2020 and 2019. Pension Plans Postretirement Benefit Plans (for the nine months ended September 30, in millions) 2020 2019 2020 2019 Service Cost: Claims and claim adjustment expenses $ 42 $ 37 $ — $ — General and administrative expenses 58 52 — — Total service cost 100 89 — — Non-Service Cost (Benefit): Claims and claim adjustment expenses (22) (25) (1) 1 General and administrative expenses (30) (35) (1) 2 Total non-service cost (benefit) (52) (60) (2) 3 Net periodic benefit cost (benefit) $ 48 $ 29 $ (2) $ 3

Leases (Tables)

Leases (Tables)	9 Months Ended
	Sep. 30, 2020
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: Three Months Ended Nine Months Ended (in millions) 2020 2019 2020 2019 Lease cost Operating leases $ 23 $ 23 $ 71 $ 68 Short-term leases (1) 1 2 2 9 Lease expense 24 25 73 77 Less: sublease income (2) — — — — Net lease cost $ 24 $ 25 $ 73 $ 77 Other information on operating leases Cash payments to settle a lease liability reported in cash flows $ 27 $ 27 $ 82 $ 77 Right-of-use assets obtained in exchange for new lease liabilities $ 8 $ 14 $ 26 $ 50 Weighted average discount rate 2.86 % 3.04 % 2.86 % 3.04 % Weighted average remaining lease term 4.9 years 5.2 years 4.9 years 5.2 years _________________________________________________________ (1) Leases with an initial term of twelve months or less are not recorded on the balance sheet.
Contractual maturities of lease liabilities	The following table presents the contractual maturities of the Company's lease liabilities: (in millions) Real Estate Lease Liability Remainder of 2020 $ 27 2021 100 2022 76 2023 56 2024 40 Thereafter 63 Total undiscounted lease payments 362 Less: present value adjustment 25 Operating lease liability $ 337

Basis of Presentation and Acc_3

Basis of Presentation and Accounting Policies (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Jan. 01, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Dec. 31, 2018
New Accounting Pronouncements
Accounting Standards Update [Extensible List]	us-gaap:AccountingStandardsUpdate201613Member
Shareholders' equity	$ (27,849)			$ (25,943)	$ (25,607)
Retained earnings [Member]
New Accounting Pronouncements
Shareholders' equity	$ (37,679)	$ (37,069)		(36,977)	$ (36,317)	$ (36,135)	$ (35,204)
Cumulative Effect, Period of Adoption, Adjustment [Member] | Retained earnings [Member]
New Accounting Pronouncements
Shareholders' equity			$ 43	$ 43

Segment Information (Details)

Segment Information (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020USD ($)	Sep. 30, 2019USD ($)	Sep. 30, 2020USD ($)segment	Sep. 30, 2019USD ($)
Segment reporting information
Number of reportable business segments | segment			3
Premiums	$ 7,380	$ 7,179	$ 21,564	$ 21,022
Net investment income	671	622	1,550	1,852
Fee income	101	121	323	346
Other revenues	86	68	195	197
Net realized investment gains (losses)	37	23	(48)	101
Total revenues	8,275	8,013	23,584	23,518
Core income (loss)	798	378	1,424	1,670
Net realized investment gains (losses), net of tax	29	18	(37)	79
Net income	827	396	1,387	1,749
Reportable Segments [Member]
Segment reporting information
Premiums	7,380	7,179	21,564	21,022
Net investment income	671	622	1,550	1,852
Fee income	101	121	323	346
Other revenues	86	68	195	196
Total segment revenues	8,238	7,990	23,632	23,416
Core income (loss)	872	449	1,643	1,892
Reportable Segments [Member] | Business Insurance [Member]
Segment reporting information
Premiums	3,841	3,882	11,440	11,407
Net investment income	498	457	1,131	1,365
Fee income	95	114	305	329
Other revenues	58	39	125	112
Total segment revenues	4,492	4,492	13,001	13,213
Core income (loss)	365	179	596	944
Reportable Segments [Member] | Business Insurance [Member] | Domestic [Member]
Segment reporting information
Premiums	3,582	3,615	10,654	10,610
Reportable Segments [Member] | Business Insurance [Member] | Domestic [Member] | Workers' compensation [Member]
Segment reporting information
Premiums	851	969	2,568	2,891
Reportable Segments [Member] | Business Insurance [Member] | Domestic [Member] | Automobile [Member]
Segment reporting information
Premiums	698	672	2,058	1,947
Reportable Segments [Member] | Business Insurance [Member] | Domestic [Member] | Commercial property [Member]
Segment reporting information
Premiums	522	496	1,544	1,429
Reportable Segments [Member] | Business Insurance [Member] | Domestic [Member] | General liability [Member]
Segment reporting information
Premiums	605	594	1,786	1,746
Reportable Segments [Member] | Business Insurance [Member] | Domestic [Member] | Commercial multi-peril [Member]
Segment reporting information
Premiums	891	872	2,660	2,568
Reportable Segments [Member] | Business Insurance [Member] | Domestic [Member] | Other [Member]
Segment reporting information
Premiums	15	12	38	29
Reportable Segments [Member] | Business Insurance [Member] | International [Member]
Segment reporting information
Premiums	259	267	786	797
Reportable Segments [Member] | Bond & Specialty Insurance [Member]
Segment reporting information
Premiums	723	653	2,083	1,891
Net investment income	58	59	155	173
Fee income	0	0	0	0
Other revenues	7	7	17	19
Total segment revenues	788	719	2,255	2,083
Core income (loss)	115	139	309	451
Reportable Segments [Member] | Bond & Specialty Insurance [Member] | Domestic [Member]
Segment reporting information
Premiums	647	595	1,876	1,727
Reportable Segments [Member] | Bond & Specialty Insurance [Member] | Domestic [Member] | General liability [Member]
Segment reporting information
Premiums	310	276	893	799
Reportable Segments [Member] | Bond & Specialty Insurance [Member] | Domestic [Member] | Fidelity and surety [Member]
Segment reporting information
Premiums	277	265	805	769
Reportable Segments [Member] | Bond & Specialty Insurance [Member] | Domestic [Member] | Other [Member]
Segment reporting information
Premiums	60	54	178	159
Reportable Segments [Member] | Bond & Specialty Insurance [Member] | International [Member]
Segment reporting information
Premiums	76	58	207	164
Reportable Segments [Member] | Personal Insurance [Member]
Segment reporting information
Premiums	2,816	2,644	8,041	7,724
Net investment income	115	106	264	314
Fee income	6	7	18	17
Other revenues	21	22	53	65
Total segment revenues	2,958	2,779	8,376	8,120
Core income (loss)	392	131	738	497
Reportable Segments [Member] | Personal Insurance [Member] | Domestic [Member]
Segment reporting information
Premiums	2,653	2,463	7,555	7,198
Reportable Segments [Member] | Personal Insurance [Member] | Domestic [Member] | Automobile [Member]
Segment reporting information
Premiums	1,391	1,344	3,896	3,962
Reportable Segments [Member] | Personal Insurance [Member] | Domestic [Member] | Homeowners and Other [Member]
Segment reporting information
Premiums	1,262	1,119	3,659	3,236
Reportable Segments [Member] | Personal Insurance [Member] | International [Member]
Segment reporting information
Premiums	163	181	486	526
Other [Member]
Segment reporting information
Other revenues	0	0	0	1
Core income (loss)	(74)	(71)	(219)	(222)
After-tax interest expense	$ 69	$ 66	$ 202	$ 206

Segment Information (Details) -

Segment Information (Details) - Assets by Segment - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Assets by segment
Total assets	$ 116,384	$ 110,122
Reportable Segments [Member]
Assets by segment
Total assets	115,753	109,510
Reportable Segments [Member] | Business Insurance [Member]
Assets by segment
Total assets	88,040	83,896
Reportable Segments [Member] | Bond & Specialty Insurance [Member]
Assets by segment
Total assets	9,483	8,599
Reportable Segments [Member] | Personal Insurance [Member]
Assets by segment
Total assets	18,230	17,015
Other assets [Member]
Assets by segment
Total assets	$ 631	$ 612

Investments (Details) - Investm

Investments (Details) - Investment Information, Debt Securities - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Jun. 30, 2020	Dec. 31, 2019
Investment disclosure details
Fixed maturities, amortized cost	$ 67,736			$ 65,281
Allowance for expected credit losses	4		$ 8	0
Gross unrealized gains	4,891			2,882
Gross unrealized losses	49			29
Fixed maturities, at fair value	72,574			68,134
Proceeds from sales of fixed maturities classified as available for sale	1,994	$ 1,801
Gross realized gains	52	51
Gross realized losses	3	$ 6
U.S. Treasury securities and obligations of U.S. government and government agencies and authorities [Member]
Investment disclosure details
Fixed maturities, amortized cost	2,083			2,076
Allowance for expected credit losses	0
Gross unrealized gains	43			19
Gross unrealized losses	0			0
Fixed maturities, at fair value	2,126			2,095
Obligations of states, municipalities and political subdivisions [Member]
Investment disclosure details
Fixed maturities, amortized cost	32,508			28,356
Allowance for expected credit losses	0
Gross unrealized gains	2,347			1,567
Gross unrealized losses	14			6
Fixed maturities, at fair value	34,841			29,917
Obligations of states, municipalities and political subdivisions, local general obligation [Member]
Investment disclosure details
Fixed maturities, amortized cost	17,019			15,490
Allowance for expected credit losses	0
Gross unrealized gains	1,267			829
Gross unrealized losses	8			4
Fixed maturities, at fair value	18,278			16,315
Obligations of states, municipalities and political subdivisions, revenue [Member]
Investment disclosure details
Fixed maturities, amortized cost	11,871			9,731
Allowance for expected credit losses	0
Gross unrealized gains	829			586
Gross unrealized losses	6			2
Fixed maturities, at fair value	12,694			10,315
Obligations of states, municipalities and political subdivisions, state general obligation [Member]
Investment disclosure details
Fixed maturities, amortized cost	1,160			1,167
Allowance for expected credit losses	0
Gross unrealized gains	91			64
Gross unrealized losses	0			0
Fixed maturities, at fair value	1,251			1,231
Obligations of states, municipalities and political subdivisions, pre-refunded [Member]
Investment disclosure details
Fixed maturities, amortized cost	2,458			1,968
Allowance for expected credit losses	0
Gross unrealized gains	160			88
Gross unrealized losses	0			0
Fixed maturities, at fair value	2,618			2,056
Debt securities issued by foreign governments [Member]
Investment disclosure details
Fixed maturities, amortized cost	952			1,167
Allowance for expected credit losses	0
Gross unrealized gains	27			8
Gross unrealized losses	0			2
Fixed maturities, at fair value	979			1,173
Mortgage-backed securities, collateralized mortgage obligations and pass-through securities [Member]
Investment disclosure details
Fixed maturities, amortized cost	2,572			3,192
Allowance for expected credit losses	0		0	0
Gross unrealized gains	158			91
Gross unrealized losses	0			3
Fixed maturities, at fair value	2,730			3,280
All other corporate bonds [Member]
Investment disclosure details
Fixed maturities, amortized cost	29,599			30,442
Allowance for expected credit losses	4		$ 8	0
Gross unrealized gains	2,314			1,195
Gross unrealized losses	35			18
Fixed maturities, at fair value	31,874			31,619
Redeemable preferred stock [Member]
Investment disclosure details
Fixed maturities, amortized cost	22			48
Allowance for expected credit losses	0
Gross unrealized gains	2			2
Gross unrealized losses	0			0
Fixed maturities, at fair value	$ 24			$ 50

Investments (Details) - Inves_2

Investments (Details) - Investment Information, Equity Securities - USD ($) $ in Millions	9 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Investment disclosure details
Equity securities, cost	$ 381		$ 376
Gross gains	52		52
Gross losses	23		3
Equity securities, at fair value	410		425
Net recognized gains (losses) on equity securities still held	(14)	$ 49
Public common stock [Member]
Investment disclosure details
Equity securities, cost	346		341
Gross gains	44		45
Gross losses	22		3
Equity securities, at fair value	368		383
Non-redeemable preferred stock [Member]
Investment disclosure details
Equity securities, cost	35		35
Gross gains	8		7
Gross losses	1		0
Equity securities, at fair value	$ 42		$ 42

Investments (Details) - Inves_3

Investments (Details) - Investment Information, Losses - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Investment disclosure details
Continuous unrealized loss position, less than 12 months, fair value	$ 3,040	$ 2,900
Continuous unrealized loss position, less than 12 months, gross unrealized losses	42	19
Continuous unrealized loss position, 12 months or longer, fair value	121	1,145
Continuous unrealized loss position, 12 months or longer, gross unrealized losses	7	10
Continuous unrealized loss position, total, fair value	3,161	4,045
Continuous unrealized loss position, total, gross unrealized losses	49	29
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	169	5
Continuous unrealized loss position, less than 12 months, gross unrealized losses	0	0
Continuous unrealized loss position, 12 months or longer, fair value	0	193
Continuous unrealized loss position, 12 months or longer, gross unrealized losses	0	0
Continuous unrealized loss position, total, fair value	169	198
Continuous unrealized loss position, total, gross unrealized losses	0	0
Obligations of states, municipalities and political subdivisions [Member]
Investment disclosure details
Continuous unrealized loss position, less than 12 months, fair value	1,751	668
Continuous unrealized loss position, less than 12 months, gross unrealized losses	14	6
Continuous unrealized loss position, 12 months or longer, fair value	0	12
Continuous unrealized loss position, 12 months or longer, gross unrealized losses	0	0
Continuous unrealized loss position, total, fair value	1,751	680
Continuous unrealized loss position, total, gross unrealized losses	14	6
Debt securities issued by foreign governments [Member]
Investment disclosure details
Continuous unrealized loss position, less than 12 months, fair value	14	257
Continuous unrealized loss position, less than 12 months, gross unrealized losses	0	1
Continuous unrealized loss position, 12 months or longer, fair value	0	147
Continuous unrealized loss position, 12 months or longer, gross unrealized losses	0	1
Continuous unrealized loss position, total, fair value	14	404
Continuous unrealized loss position, total, gross unrealized losses	0	2
Mortgage-backed securities, collateralized mortgage obligations and pass-through securities [Member]
Investment disclosure details
Continuous unrealized loss position, less than 12 months, fair value	11	399
Continuous unrealized loss position, less than 12 months, gross unrealized losses	0	2
Continuous unrealized loss position, 12 months or longer, fair value	1	131
Continuous unrealized loss position, 12 months or longer, gross unrealized losses	0	1
Continuous unrealized loss position, total, fair value	12	530
Continuous unrealized loss position, total, gross unrealized losses	0	3
All other corporate bonds [Member]
Investment disclosure details
Continuous unrealized loss position, less than 12 months, fair value	1,095	1,571
Continuous unrealized loss position, less than 12 months, gross unrealized losses	28	10
Continuous unrealized loss position, 12 months or longer, fair value	120	662
Continuous unrealized loss position, 12 months or longer, gross unrealized losses	7	8
Continuous unrealized loss position, total, fair value	1,215	2,233
Continuous unrealized loss position, total, gross unrealized losses	$ 35	$ 18

Investments (Details) - Allowan

Investments (Details) - Allowance for Expected Credit Losses - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Allowance for expected credit losses [Roll Forward]
Allowance for expected credit losses on fixed maturities classified as available-for-sale, balance, beginning of period	$ 8		$ 0
Additions for expected credit losses on securities where no credit losses were previously recognized	1		9
Additions (reductions) for expected credit losses on securities where credit losses were previously recognized	(3)		(3)
Reductions due to sales/defaults of credit-impaired securities	(2)		(2)
Reductions for impairments of securities which the Company intends to sell or more likely than not will be required to sell	0		0
Allowance for expected credit losses on fixed maturities classified as available-for-sale, balance, end of period	4		4
Credit impairment charges recognized in net realized investment gains (losses) on securities which the Company intends to sell and for which an allowance for credit loss was not previously recorded			14
Total net credit impairment (recoveries) included in net realized investment gains (losses) in the consolidated statement of income	$ (4)
Total net credit impairment charges included in net realized investment gains (losses) in the consolidated statement of income		$ 0	58	$ 2
Total credit impairment charges included in net realized investment gains (losses) in the consolidated statement of income related to other investments			$ 40
Credit losses on fixed maturities recognized in the consolidated statement of income, as a percentage of the fixed maturity portfolio on a pre-tax basis (less than)	1.00%	1.00%	1.00%	1.00%
Credit losses on fixed maturities recognized in the consolidated statement of income, as a percentage of shareholders' equity on an after-tax basis (less than)	1.00%	1.00%	1.00%	1.00%
Mortgage-backed securities, collateralized mortgage obligations and pass-through securities [Member]
Allowance for expected credit losses [Roll Forward]
Allowance for expected credit losses on fixed maturities classified as available-for-sale, balance, beginning of period	$ 0		$ 0
Additions for expected credit losses on securities where no credit losses were previously recognized	0		0
Additions (reductions) for expected credit losses on securities where credit losses were previously recognized	0		0
Reductions due to sales/defaults of credit-impaired securities	0		0
Reductions for impairments of securities which the Company intends to sell or more likely than not will be required to sell	0		0
Allowance for expected credit losses on fixed maturities classified as available-for-sale, balance, end of period	0		0
All other corporate bonds [Member]
Allowance for expected credit losses [Roll Forward]
Allowance for expected credit losses on fixed maturities classified as available-for-sale, balance, beginning of period	8		0
Additions for expected credit losses on securities where no credit losses were previously recognized	1		9
Additions (reductions) for expected credit losses on securities where credit losses were previously recognized	(3)		(3)
Reductions due to sales/defaults of credit-impaired securities	(2)		(2)
Reductions for impairments of securities which the Company intends to sell or more likely than not will be required to sell	0		0
Allowance for expected credit losses on fixed maturities classified as available-for-sale, balance, end of period	$ 4		$ 4

Investments (Details) - Other I

Investments (Details) - Other Investments	9 Months Ended
	Sep. 30, 2020
Investments [Abstract]
Availability of financial information provided by hedge funds following the date of the reporting	1 month
Availability of financial information provided by private equity and real estate partnerships following the date of the reporting, maximum	3 months

Fair Value Measurements (Detail

Fair Value Measurements (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Fair Value Disclosures [Abstract]
Percent of fixed maturities for which a pricing service estimates fair value	99.00%	99.00%
Fair value of the fixed maturities for which the Company used an internal pricing matrix	$ 89	$ 73
Fair value of the fixed maturities for which the Company received a broker quote	3	28
Estimated fair value of put/call option	$ 7	$ 8

Fair Value Measurements (Deta_2

Fair Value Measurements (Details) - Fair Value Hierarchy - Recurring basis [Member] - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
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	$ 73,032	$ 68,595
Other liabilities measured on a recurring basis	7	8
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	72,574	68,134
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	2,126	2,095
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	34,841	29,917
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	979	1,173
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	2,730	3,280
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	31,874	31,619
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	24	50
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	410	425
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	368	383
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	42
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	48	36
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	2,535	2,507
Other liabilities measured on a recurring basis	0	0
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	2,132	2,095
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	2,126	2,095
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
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
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
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	6	0
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	0
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	389	396
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	368	383
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	21	13
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	14	16
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	70,371	65,967
Other liabilities measured on a recurring basis	0	0
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	70,350	65,938
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
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	34,830	29,905
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	979	1,173
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	2,730	3,280
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	31,787	31,530
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	24	50
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	21	29
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
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	21	29
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
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	126	121
Other liabilities measured on a recurring basis	7	8
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	92	101
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
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	11	12
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
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	0
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	81	89
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
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
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
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
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	$ 34	$ 20

Fair Value Measurements (Deta_3

Fair Value Measurements (Details) - Financial Instruments - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Financial Instruments
Short-term securities	$ 6,329	$ 4,943
Carrying Value [Member]
Financial Instruments
Short-term securities	6,329	4,943
Debt	6,950	6,458
Commercial paper	100	100
Fair Value [Member]
Financial Instruments
Short-term securities	6,329	4,943
Debt	9,083	8,049
Commercial paper	100	100
Fair Value [Member] | Level 1 [Member]
Financial Instruments
Short-term securities	977	685
Debt	0	0
Commercial paper	0	0
Fair Value [Member] | Level 2 [Member]
Financial Instruments
Short-term securities	5,307	4,204
Debt	9,083	8,049
Commercial paper	100	100
Fair Value [Member] | Level 3 [Member]
Financial Instruments
Short-term securities	45	54
Debt	0	0
Commercial paper	$ 0	$ 0

Allowance for Expected Credit_3

Allowance for Expected Credit Losses (Details) - Changes in the Allowance for Expected Credit Losses on Premiums Receivable - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2020
Credit Loss [Abstract]
Premiums receivable (net of allowance for expected credit losses), balance, beginning of period	$ 8,459	$ 7,909
Premiums receivable (net of allowance for expected credit losses), balance, end of period	8,225	8,225
Premiums receivable, allowance for expected credit losses [Roll Forward]
Premiums receivable, allowance for expected credit losses, beginning balance	94	49
Current period change for expected credit losses	17	84
Write-offs of uncollectible premiums receivable	15	37
Premiums receivable, allowance for expected credit losses, ending balance	$ 96	$ 96

Allowance for Expected Credit_4

Allowance for Expected Credit Losses (Details) - Changes in the Allowance for Estimated Uncollectible Reinsurance - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2020
Reinsurance recoverables, allowance for uncollectible reinsurance
Reinsurance recoverables (net of allowance for estimated uncollectible reinsurance), balance, beginning of period	$ 8,093	$ 8,235
Reinsurance recoverables (net of allowance for estimated uncollectible reinsurance), balance, end of period	8,317	8,317
Reinsurance recoverables, allowance for uncollectible reinsurance [Roll Forward]
Reinsurance recoverables, allowance for uncollectible reinsurance, beginning balance	156	92
Reinsurance recoverables, allowance for estimated uncollectible reinsurance	140	$ 140
Accounting Standards Update [Extensible List]		us-gaap:AccountingStandardsUpdate201613Member
Current period change for estimated uncollectible reinsurance	(16)	$ (5)
Write-offs of uncollectible reinsurance recoverables	0	0
Reinsurance recoverables, allowance for uncollectible reinsurance, ending balance	$ 140	140
Cumulative Effect, Period of Adoption, Adjustment [Member]
Reinsurance recoverables, allowance for uncollectible reinsurance [Roll Forward]
Reinsurance recoverables, allowance for uncollectible reinsurance, beginning balance		53
Reinsurance recoverables, allowance for estimated uncollectible reinsurance		$ 53

Allowance for Expected Credit_5

Allowance for Expected Credit Losses (Details) - Narrative - Reinsurer Concentration Risk [Member] $ in Millions	9 Months Ended
	Sep. 30, 2020USD ($)
Reinsurance Recoverables [Member] | Reinsurer Group Rated by A.M. Best [Member] | A.M. Best, Rating Provided [Member]
Reinsurance recoverables, credit quality indicator
Reinsurance recoverables, after deducting mandatory pools and associations and before allowances for expected credit losses	$ 5,820
Concentration risk percentage	88.00%
Reinsurance Recoverables [Member] | Reinsurer Group Not Rated by A.M. Best [Member]
Reinsurance recoverables, credit quality indicator
Concentration risk percentage	12.00%
Reinsurance Recoverables [Member] | Captive Insurance Companies [Member]
Reinsurance recoverables, credit quality indicator
Concentration risk percentage	6.00%
Reinsurance Recoverables [Member] | Voluntary Pools [Member]
Reinsurance recoverables, credit quality indicator
Concentration risk percentage	1.00%
Reinsurance Recoverables [Member] | Other Companies [Member]
Reinsurance recoverables, credit quality indicator
Concentration risk percentage	5.00%
Reinsurance Recoverables Rated by A.M. Best [Member] | Reinsurer Group Rated by A.M. Best [Member] | A.M. Best, A- Rating Or Better [Member]
Reinsurance recoverables, credit quality indicator
Concentration risk percentage	93.00%

Allowance for Expected Credit_6

Allowance for Expected Credit Losses (Details) - Changes in the Allowance for Expected Credit Losses on Contractholder Receivables (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2020
Credit Loss [Abstract]
Contractholder receivables (net of the allowance for expected credit losses), balance, beginning of period	$ 4,314	$ 4,599
Contractholder receivables (net of the allowance for expected credit losses), balance, end of period	4,347	4,347
Contractholder receivables, allowance for expected credit losses [Roll Forward]
Contractholder receivables, allowance for expected credit losses, beginning balance	22	20
Current period change for expected credit losses	0	2
Write-offs of uncollectible contractholder receivables	1	1
Contractholder receivables, allowance for expected credit losses, ending balance	$ 21	$ 21

Goodwill and Other Intangible_3

Goodwill and Other Intangible Assets (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Goodwill by segment
Goodwill	$ 3,945	$ 3,961
Reportable Segments [Member] | Business Insurance [Member]
Goodwill by segment
Goodwill	2,589	2,601
Reportable Segments [Member] | Bond & Specialty Insurance [Member]
Goodwill by segment
Goodwill	550	550
Reportable Segments [Member] | Personal Insurance [Member]
Goodwill by segment
Goodwill	780	784
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	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Other intangible assets by major asset class
Intangible assets subject to amortization, gross carrying amount	$ 302		$ 302		$ 304
Intangible assets subject to amortization, accumulated amortization	210		210		200
Intangible assets subject to amortization, net	92		92		104
Intangible assets not subject to amortization	226		226		226
Total other intangible assets, gross carrying amount	528		528		530
Total other intangible assets, net	318		318		330
Amortization expense of intangible assets	4	$ 4	11	$ 12
Estimated intangible asset amortization expense, remainder of 2020	4		4
Estimated intangible asset amortization expense, 2021	14		14
Estimated intangible asset amortization expense, 2022	13		13
Estimated intangible asset amortization expense, 2023	12		12
Estimated intangible asset amortization expense, 2024	12		12
Customer-related [Member]
Other intangible assets by major asset class
Intangible assets subject to amortization, gross carrying amount	98		98		99
Intangible assets subject to amortization, accumulated amortization	28		28		21
Intangible assets subject to amortization, net	70		70		78
Contract-based [Member]
Other intangible assets by major asset class
Intangible assets subject to amortization, gross carrying amount	204		204		205
Intangible assets subject to amortization, accumulated amortization	182		182		179
Intangible assets subject to amortization, net	22		22		$ 26
Insurance Contracts Acquired in Business Combination [Member]
Other intangible assets by major asset class
Estimated intangible asset amortization expense, remainder of 2020	1		1
Estimated intangible asset amortization expense, 2021	4		4
Estimated intangible asset amortization expense, 2022	3		3
Estimated intangible asset amortization expense, 2023	3		3
Estimated intangible asset amortization expense, 2024	$ 2		$ 2

Insurance Claim Reserves (Detai

Insurance Claim Reserves (Details) - Reserve Detail for Claims and Claim Adjustment Expenses - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Jun. 30, 2020	Dec. 31, 2019
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	$ 51,849
Accounting Standards Update [Extensible List]	us-gaap:AccountingStandardsUpdate201613Member
Reinsurance recoverables, allowance for estimated uncollectible reinsurance	$ 140		$ 156	$ 92
Claims and claim adjustment expense reserves at end of period	54,418
Cumulative Effect, Period of Adoption, Adjustment [Member]
Reconciliation of beginning and ending reserve balances for claims and claim adjustment expenses [Roll Forward]
Reinsurance recoverables, allowance for estimated uncollectible reinsurance				53
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	51,836	$ 50,653
Reinsurance recoverables on unpaid losses	8,035	8,182
Net reserves at beginning of year	43,854	42,471
Estimated claims and claim adjustment expenses for claims arising in the current year	14,809	14,193
Estimated increase (decrease) in claims and claim adjustment expenses for claims arising in prior years	(108)	214
Total increases	14,701	14,407
Claims and claim adjustment expense payments for claims arising in current year	4,960	5,174
Claims and claim adjustment expense payments for claims arising in prior years	7,246	8,034
Total payments	12,206	13,208
Unrealized foreign exchange (gain) loss	(62)	12
Net reserves at end of period	46,287	43,682
Reinsurance recoverables on unpaid losses	8,119	7,916
Claims and claim adjustment expense reserves at end of period	54,406	$ 51,598
Amount of increase in gross claims and claim adjustment expense reserves	2,570
Amount of increase in reinsurance recoverables on unpaid losses	84
Property-casualty [Member] | Cumulative Effect, Period of Adoption, Adjustment [Member]
Reconciliation of beginning and ending reserve balances for claims and claim adjustment expenses [Roll Forward]
Reinsurance recoverables, allowance for estimated uncollectible reinsurance				$ 53
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	13
Claims and claim adjustment expense reserves at end of period	$ 12

Insurance Claim Reserves (Det_2

Insurance Claim Reserves (Details) - Subrogation Amounts $ in Millions	3 Months Ended
	Sep. 30, 2020USD ($)
Insurance Loss Reserves [Abstract]
Subrogation benefit recognized in earnings	$ 403
Subrogation payments received	$ 366

Insurance Claim Reserves (Det_3

Insurance Claim Reserves (Details) - Prior Year Reserve Development - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Liability for claims and claim adjustment expense
Subrogation recoveries	$ 403
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			$ 108	$ (214)
Net favorable (unfavorable) prior year reserve development impacting the Company's results of operations			171	(120)
Accretion expense			36	37
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	(220)	$ (316)	(215)	(266)
Subrogation recoveries	81		81
Property-casualty [Member] | Business Insurance [Member] | Asbestos reserves [Member]
Liability for claims and claim adjustment expense
Increase to reserves	295	220	295	220
Property-casualty [Member] | Business Insurance [Member] | Environmental reserves [Member]
Liability for claims and claim adjustment expense
Increase to reserves				68
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	0	3	(33)	45
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	362	$ 19	419	$ 101
Subrogation recoveries	$ 322		$ 322

Other Comprehensive Income an_3

Other Comprehensive Income and Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Accumulated other comprehensive income [Roll Forward]
Balance, beginning of year			$ 25,943
Other comprehensive income, net of taxes	$ 256	$ 419	1,498	$ 2,484
Balance, end of period	27,849	25,607	27,849	25,607
Pre-tax components of other comprehensive income (loss) and related tax expense (benefit)
Other comprehensive income before income taxes	309	541	1,918	3,147
Income tax expense (benefit)	53	122	420	663
Other comprehensive income, net of taxes	256	419	1,498	2,484
Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated other comprehensive income [Roll Forward]
Balance, beginning of year	1,882	206	640	(1,859)
Other comprehensive income (loss) before reclassifications	258		1,472
Amounts reclassified from accumulated other comprehensive income	(2)		26
Other comprehensive income, net of taxes	256	419	1,498	2,484
Balance, end of period	2,138	625	2,138	625
Pre-tax components of other comprehensive income (loss) and related tax expense (benefit)
Other comprehensive income before income taxes	309	541	1,918	3,147
Income tax expense (benefit)	53	122	420	663
Other comprehensive income, net of taxes	256	419	1,498	2,484
Changes in Net Unrealized Gains 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	3,459		2,057
Other comprehensive income (loss) before reclassifications	189		1,597
Amounts reclassified from accumulated other comprehensive income	(18)		(24)
Other comprehensive income, net of taxes	171	478	1,573	2,468
Balance, end of period	3,630		3,630
Pre-tax components of other comprehensive income (loss) and related tax expense (benefit)
Other comprehensive income before income taxes	217	605	2,001	3,129
Income tax expense (benefit)	46	127	428	661
Other comprehensive income, net of taxes	171	478	1,573	2,468
Changes in Net Unrealized Gains on Investment Securities Having Credit Losses Recognized in the Consolidated Statement of Income [Member]
Accumulated other comprehensive income [Roll Forward]
Balance, beginning of year	187		189
Other comprehensive income (loss) before reclassifications	(5)		(7)
Amounts reclassified from accumulated other comprehensive income	0		0
Other comprehensive income, net of taxes	(5)	(2)	(7)	(1)
Balance, end of period	182		182
Pre-tax components of other comprehensive income (loss) and related tax expense (benefit)
Other comprehensive income before income taxes	(7)	(3)	(10)	(2)
Income tax expense (benefit)	(2)	(1)	(3)	(1)
Other comprehensive income, net of taxes	(5)	(2)	(7)	(1)
Net Benefit Plan Assets and Obligations Recognized in Shareholders' Equity [Member]
Accumulated other comprehensive income [Roll Forward]
Balance, beginning of year	(811)		(846)
Other comprehensive income (loss) before reclassifications	0		1
Amounts reclassified from accumulated other comprehensive income	16		50
Other comprehensive income, net of taxes	16	11	51	32
Balance, end of period	(795)		(795)
Pre-tax components of other comprehensive income (loss) and related tax expense (benefit)
Other comprehensive income before income taxes	20	14	64	40
Income tax expense (benefit)	4	3	13	8
Other comprehensive income, net of taxes	16	11	51	32
Net Unrealized Foreign Currency Translation [Member]
Accumulated other comprehensive income [Roll Forward]
Balance, beginning of year	(953)		(760)
Other comprehensive income (loss) before reclassifications	74		(119)
Amounts reclassified from accumulated other comprehensive income	0		0
Other comprehensive income, net of taxes	74	(68)	(119)	(15)
Balance, end of period	(879)		(879)
Pre-tax components of other comprehensive income (loss) and related tax expense (benefit)
Other comprehensive income before income taxes	79	(75)	(137)	(20)
Income tax expense (benefit)	5	(7)	(18)	(5)
Other comprehensive income, net of taxes	$ 74	$ (68)	$ (119)	$ (15)

Other Comprehensive Income an_4

Other Comprehensive Income and Accumulated Other Comprehensive Income (Details) - Reclassifications - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Reclassification Adjustment out of Accumulated Other Comprehensive Income
Reclassification adjustment impacting net realized investment gains (losses) on the income statement	$ (37)	$ (23)	$ 48	$ (101)
Reclassification adjustment impacting claims and claim adjustment expenses on the income statement	4,886	5,230	14,782	14,493
Reclassification adjustment impacting general and administrative expense on the income statement	1,109	1,098	3,367	3,280
Total reclassifications	(986)	(432)	(1,621)	(2,064)
Income tax (expense) benefit	(159)	(36)	(234)	(315)
Amounts reclassified from accumulated other comprehensive income, net of taxes	(827)	(396)	(1,387)	(1,749)
Accumulated Other Comprehensive Income (Loss) [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income
Total reclassifications	(3)	(2)	32	(5)
Income tax (expense) benefit	(1)	0	6	(1)
Amounts reclassified from accumulated other comprehensive income, net of taxes	(2)	(2)	26	(4)
Changes in Net Unrealized Gains 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 (losses) on the income statement	(23)	(14)	(31)	(43)
Income tax (expense) benefit	(5)	(3)	(7)	(9)
Amounts reclassified from accumulated other comprehensive income, net of taxes	(18)	(11)	(24)	(34)
Changes in Net Unrealized Gains 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 (losses) on the income statement	0	0	0	0
Income tax (expense) benefit	0	0	0	0
Amounts reclassified from accumulated other comprehensive income, net of taxes	0	0	0	0
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	8	4	26	15
Reclassification adjustment impacting general and administrative expense on the income statement	12	8	37	23
Total reclassifications	20	12	63	38
Income tax (expense) benefit	4	3	13	8
Amounts reclassified from accumulated other comprehensive income, net of taxes	16	9	50	30
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 (losses) on the income statement	0	0	0	0
Income tax (expense) benefit	0	0	0	0
Amounts reclassified from accumulated other comprehensive income, net of taxes	$ 0	$ 0	$ 0	$ 0

Debt (Details)

Debt (Details) - USD ($) $ in Millions	Apr. 27, 2020	Sep. 30, 2020	Sep. 30, 2019
Debt Instrument
Net proceeds of issuance, after the deduction of the underwriting discount and expenses		$ 490	$ 492
Senior Notes [Member] | 2.55% Senior Notes due April 27, 2050 [Member]
Debt Instrument
Debt, principal amount	$ 500
Interest rate (percent)	2.55%
Net proceeds of issuance, after the deduction of the underwriting discount and expenses	$ 490
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	0.25%

Common Share Repurchases (Detai

Common Share Repurchases (Details) $ / shares in Units, $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2020USD ($)shares	Sep. 30, 2020USD ($)$ / sharesshares
Treasury Stock Transactions, Excluding Value of Shares Reissued [Abstract]
Number of shares repurchased (in shares) | shares	0	3,500,000
Cost of shares repurchased		$ 425,000
Average cost per share repurchased (in dollars per share) | $ / shares		$ 123.09
Number of shares acquired to cover tax withholding costs and exercise costs (in shares) | shares	1,368	300,000
Cost of shares acquired to cover tax withholding costs and exercise costs	$ 159	$ 46,000
Remaining capacity under share repurchase authorization	$ 1,360,000	$ 1,360,000

Earnings per Share (Details)

Earnings per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Earnings Per Share Reconciliation [Abstract]
Net income	$ 827	$ 396	$ 1,387	$ 1,749
Participating share-based awards — allocated income	(6)	(3)	(9)	(12)
Net income available to common shareholders -- basic	821	393	1,378	1,737
Net income available to common shareholders -- diluted	$ 821	$ 393	$ 1,378	$ 1,737
Weighted average shares outstanding, basic (in shares)	253.3	259.2	253.5	261.1
Weighted average effects of dilutive securities - stock options and performance shares (in shares)	1	2.6	1	2.3
Weighted average shares outstanding, diluted (in shares)	254.3	261.8	254.5	263.4
Net income per common share, basic (in dollars per share)	$ 3.24	$ 1.52	$ 5.44	$ 6.65
Net income per common share, diluted (in dollars per share)	$ 3.23	$ 1.50	$ 5.41	$ 6.59

Share-Based Incentive Compens_3

Share-Based Incentive Compensation (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Share-based Payment Arrangement [Abstract]
Stock options vested at end of period, number (in shares)	7,474,888		7,474,888
Stock options vested at end of period, weighted average exercise price (in dollars per share)	$ 114.76		$ 114.76
Stock options vested at end of period, weighted average contractual life remaining (in years)			5 years 6 months
Stock options vested at end of period, aggregate intrinsic value	$ 36		$ 36
Stock options exercisable at end of period, number (in shares)	5,210,232		5,210,232
Stock options exercisable at end of period, weighted average exercise price (in dollars per share)	$ 107.04		$ 107.04
Stock options exercisable at end of period, weighted average contractual life remaining (in years)			4 years 2 months 12 days
Stock options exercisable at end of period, aggregate intrinsic value	$ 36		$ 36
Total compensation cost recognized in earnings for all share-based incentive compensation awards	33	$ 32	113	$ 112
Tax benefit recognized in earnings related to compensation costs	6	$ 6	20	$ 20
Total unrecognized compensation cost related to all nonvested share-based incentive compensation awards	$ 165		$ 165
Weighted-average period of recognition for unrecognized compensation cost (in years)			1 year 9 months 18 days

Pension Plans, Retirement Ben_3

Pension Plans, Retirement Benefits and Savings Plans (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Pension Plans [Member]
Defined benefit plan disclosure
Service cost	$ 34	$ 30	$ 100	$ 89
Interest cost on benefit obligation	29	35	86	105
Expected return on plan assets	(69)	(69)	(206)	(206)
Net periodic benefit cost, amortization of unrecognized prior service benefit	(1)	0	(1)	(1)
Net periodic benefit cost, amortization of unrecognized net actuarial (gain) loss	23	14	69	42
Total non-service cost (benefit)	(18)	(20)	(52)	(60)
Net periodic benefit cost (benefit)	16	10	48	29
Pension Plans [Member] | Claims and claim adjustment expenses [Member]
Defined benefit plan disclosure
Service cost	14	13	42	37
Total non-service cost (benefit)	(8)	(9)	(22)	(25)
Pension Plans [Member] | General and administrative expenses [Member]
Defined benefit plan disclosure
Service cost	20	17	58	52
Total non-service cost (benefit)	(10)	(11)	(30)	(35)
Postretirement Benefit Plans [Member]
Defined benefit plan disclosure
Service cost	0	0	0	0
Interest cost on benefit obligation	1	2	3	6
Expected return on plan assets	0	0	0	0
Net periodic benefit cost, amortization of unrecognized prior service benefit	(1)	(1)	(3)	(3)
Net periodic benefit cost, amortization of unrecognized net actuarial (gain) loss	(1)	0	(2)	0
Total non-service cost (benefit)	(1)	1	(2)	3
Net periodic benefit cost (benefit)	(1)	1	(2)	3
Postretirement Benefit Plans [Member] | Claims and claim adjustment expenses [Member]
Defined benefit plan disclosure
Service cost	0	0	0	0
Total non-service cost (benefit)	(1)	0	(1)	1
Postretirement Benefit Plans [Member] | General and administrative expenses [Member]
Defined benefit plan disclosure
Service cost	0	0	0	0
Total non-service cost (benefit)	$ 0	$ 1	$ (1)	$ 2

Leases (Details)

Leases (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Leases [Abstract]
Operating leases	$ 23	$ 23	$ 71	$ 68
Short-term leases	1	2	2	9
Lease expense	24	25	73	77
Less: sublease income	0	0	0	0
Net lease cost	24	25	73	77
Cash payments to settle a lease liability reported in cash flows	27	27	82	77
Right-of-use assets obtained in exchange for new lease liabilities	$ 8	$ 14	$ 26	$ 50
Weighted average discount rate (percent)	2.86%	3.04%	2.86%	3.04%
Weighted average remaining lease term (in years)	4 years 10 months 24 days	5 years 2 months 12 days	4 years 10 months 24 days	5 years 2 months 12 days

Leases (Details) - Contractual

Leases (Details) - Contractual Maturities of Lease Liabilities $ in Millions	Sep. 30, 2020USD ($)
Leases [Abstract]
Lease payments due, remainder of 2020	$ 27
Lease payments due, 2021	100
Lease payments due, 2022	76
Lease payments due, 2023	56
Lease payments due, 2024	40
Lease payments due, thereafter	63
Total undiscounted lease payments	362
Less: present value adjustment	25
Operating lease liability	$ 337

Contingencies, Commitments an_2

Contingencies, Commitments and Guarantees (Details) - Commitments - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Contingencies, Commitments and Guarantees [Abstract]
Unfunded commitments to private equity limited partnerships and real estate partnerships	$ 1,650	$ 1,660

Contingencies, Commitments an_3

Contingencies, Commitments and Guarantees (Details) - Guarantees $ in Millions	Sep. 30, 2020USD ($)
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