The Travelers Companies, Inc. (TRV) 10-Q 21 Apr 20 2020 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2020	Apr. 17, 2020
Document and Entity Information
Document type	10-Q
Document quarterly report	true
Document period end date	Mar. 31, 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		252,835,833
Central index key	0000086312
Amendment flag	false
Current fiscal year end date	--12-31
Document fiscal year focus	2020
Document fiscal period focus	Q1

Consolidated Statement of Incom

Consolidated Statement of Income (Unaudited) - USD ($) shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Revenues
Premiums	$ 7,229	$ 6,855
Net investment income	611	582
Fee income	108	109
Net realized investment gains (losses)	(98)	53
Other revenues	58	72
Total revenues	7,908	7,671
Claims and expenses
Claims and claim adjustment expenses	4,789	4,442
Amortization of deferred acquisition costs	1,178	1,117
General and administrative expenses	1,137	1,057
Interest expense	84	88
Total claims and expenses	7,188	6,704
Income before income taxes	720	967
Income tax expense	120	171
Net income	$ 600	$ 796
Net income per share
Basic (in dollars per share)	$ 2.34	$ 3.01
Diluted (in dollars per share)	$ 2.33	$ 2.99
Weighted average number of common shares outstanding
Basic (in shares)	254.4	262.9
Diluted (in shares)	255.9	264.8
Cash dividends declared per common share (in dollars per share)	$ 0.82	$ 0.77

Consolidated Statement of Compr

Consolidated Statement of Comprehensive Income (Loss) (Unaudited) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Statement of Comprehensive Income [Abstract]
Net income	$ 600	$ 796
Other comprehensive income (loss):
Changes in net unrealized gains on investment securities having no credit losses recognized in the consolidated statement of income	(575)	1,416
Changes in net unrealized gains on investment securities having credit losses recognized in the consolidated statement of income	(6)	5
Net changes in benefit plan assets and obligations	23	12
Net changes in unrealized foreign currency translation	(268)	50
Other comprehensive income (loss) before income taxes	(826)	1,483
Income tax expense (benefit)	(137)	306
Other comprehensive income (loss), net of taxes	(689)	1,177
Comprehensive income (loss)	$ (89)	$ 1,973

Consolidated Balance Sheet (Una

Consolidated Balance Sheet (Unaudited at March 31, 2020) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Assets
Fixed maturities, available for sale, at fair value (amortized cost $65,630 and $65,281; allowance for expected credit losses of $4 at March 31, 2020)	$ 67,897	$ 68,134
Equity securities, at fair value (cost $372 and $376)	342	425
Real estate investments	966	963
Short-term securities	4,033	4,943
Other investments	3,412	3,419
Total investments	76,650	77,884
Cash	544	494
Investment income accrued	567	618
Premiums receivable (net of allowance for expected credit losses of $78 at March 31, 2020)	8,202	7,909
Reinsurance recoverables (net of allowance for estimated uncollectible reinsurance of $149 at March 31, 2020)	8,152	8,235
Ceded unearned premiums	1,030	689
Deferred acquisition costs	2,298	2,273
Deferred taxes	9	0
Contractholder receivables (net of allowance for expected credit losses of $20 at March 31, 2020)	4,634	4,599
Goodwill	3,915	3,961
Other intangible assets	322	330
Other assets	3,113	3,130
Total assets	109,436	110,122
Liabilities
Claims and claim adjustment expense reserves	51,957	51,849
Unearned premium reserves	14,941	14,604
Contractholder payables	4,654	4,619
Payables for reinsurance premiums	634	363
Deferred taxes	0	137
Debt	6,559	6,558
Other liabilities	5,487	6,049
Total liabilities	84,232	84,179
Shareholders’ equity
Common stock (1,750.0 shares authorized; 252.9 and 255.5 shares issued, 252.8 and 255.5 shares outstanding)	23,542	23,469
Retained earnings	37,325	36,977
Accumulated other comprehensive income (loss)	(49)	640
Treasury stock, at cost (525.9 and 522.1 shares)	(35,614)	(35,143)
Total shareholders’ equity	25,204	25,943
Total liabilities and shareholders’ equity	$ 109,436	$ 110,122

Consolidated Balance Sheet Pare

Consolidated Balance Sheet Parentheticals (Unaudited at March 31, 2020) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Fixed maturities, available for sale, amortized cost	$ 65,630	$ 65,281
Fixed maturities, available for sale, allowance for expected credit losses	4	0
Equity securities, cost	372	376
Premiums receivable, allowance for expected credit losses	78	49
Reinsurance recoverables, allowance for estimated uncollectible reinsurance	149	92
Contractholder receivables, allowance for expected credit losses	$ 20	$ 20
Common stock, shares authorized (in shares)	1,750,000,000	1,750,000,000
Common stock, shares issued (in shares)	252,900,000	255,500,000
Common stock, shares outstanding (in shares)	252,800,000	255,500,000
Treasury stock, at cost (in shares)	525,900,000	522,100,000

Consolidated Statement of Chang

Consolidated Statement of Changes in Shareholders' Equity (Unaudited) - USD ($) shares in Millions, $ in Millions	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	$ 35,204		$ (1,859)	$ (33,595)
Balance, beginning of year at Dec. 31, 2018		23,144	35,204		(1,859)	(33,595)
Shareholders' Equity [Roll Forward]
Employee share-based compensation		54
Compensation amortization under share-based plans and other changes		45
Shareholders' equity	$ 24,340	23,243	35,795		(682)	(34,016)
Net income	796		796
Dividends			(204)
Other			(1)
Other comprehensive income (loss)	1,177				1,177
Treasury stock acquired — share repurchase authorization						(375)
Net shares acquired related to employee share-based compensation plans						(46)
Balance, end of period at Mar. 31, 2019	24,340	23,243	35,795		(682)	(34,016)
Balance, beginning of year (in shares) at Dec. 31, 2018							263.6
Common shares outstanding
Treasury stock acquired - share repurchase authorization (in shares)							(2.9)
Net shares issued under employee share-based compensation plans (in shares)							1.2
Balance, end of period (in shares) at Mar. 31, 2019							261.9
Shareholders' Equity [Roll Forward]
Shareholders' equity	24,340	23,243	35,795		(682)	(34,016)
Shareholders' equity	25,943	23,469	36,977		640	(35,143)
Shareholders' equity | Accounting Standards Update 2016-13 [Member]				$ (43)
Balance, beginning of year at Dec. 31, 2019	25,943	23,469	36,977		640	(35,143)
Balance, beginning of year (Accounting Standards Update 2016-13 [Member]) at Dec. 31, 2019				(43)
Shareholders' Equity [Roll Forward]
Employee share-based compensation		27
Compensation amortization under share-based plans and other changes		46
Shareholders' equity	25,943	23,542	37,325		(49)	(35,614)
Shareholders' equity | Accounting Standards Update 2016-13 [Member]				$ (43)
Net income	600		600
Dividends			(210)
Other			1
Other comprehensive income (loss)	(689)				(689)
Treasury stock acquired — share repurchase authorization	(425)					(425)
Net shares acquired related to employee share-based compensation plans	(46)					(46)
Balance, end of period at Mar. 31, 2020	$ 25,204	23,542	37,325		(49)	(35,614)
Balance, beginning of year (in shares) at Dec. 31, 2019	255.5						255.5
Common shares outstanding
Treasury stock acquired - share repurchase authorization (in shares)	(3.5)						(3.5)
Net shares issued under employee share-based compensation plans (in shares)							0.8
Balance, end of period (in shares) at Mar. 31, 2020	252.8						252.8
Shareholders' Equity [Roll Forward]
Shareholders' equity	$ 25,204	$ 23,542	$ 37,325		$ (49)	$ (35,614)

Consolidated Statement of Cash

Consolidated Statement of Cash Flows (Unaudited) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Cash flows from operating activities
Net income	$ 600	$ 796
Adjustments to reconcile net income to net cash provided by operating activities:
Net realized investment (gains) losses	98	(53)
Depreciation and amortization	203	211
Deferred federal income tax expense	6	32
Amortization of deferred acquisition costs	1,178	1,117
Equity in income from other investments	(67)	(34)
Premiums receivable	(326)	(434)
Reinsurance recoverables	(15)	98
Deferred acquisition costs	(1,215)	(1,185)
Claims and claim adjustment expense reserves	388	(2)
Unearned premium reserves	414	551
Other operating activities	(636)	(458)
Net cash provided by operating activities	628	639
Cash flows from investing activities
Proceeds from maturities of fixed maturities	1,461	1,556
Proceeds from sales of investments:
Fixed maturities	388	769
Equity securities	33	39
Other investments	64	105
Purchases of investments:
Fixed maturities	(2,630)	(2,914)
Equity securities	(35)	(22)
Real estate investments	(16)	(77)
Other investments	(103)	(146)
Net sales (purchases) of short-term securities	906	(109)
Securities transactions in course of settlement	85	295
Other investing activities	(69)	(82)
Net cash provided by (used in) investing activities	84	(586)
Cash flows from financing activities
Treasury stock acquired — share repurchase authorization	(425)	(375)
Treasury stock acquired — net employee share-based compensation	(46)	(46)
Dividends paid to shareholders	(210)	(205)
Issuance of debt	0	492
Issuance of common stock — employee share options	31	63
Net cash used in financing activities	(650)	(71)
Effect of exchange rate changes on cash	(12)	2
Net increase (decrease) in cash	50	(16)
Cash at beginning of year	494	373
Cash at end of period	544	357
Supplemental disclosure of cash flow information
Income taxes paid	15	5
Interest paid	$ 60	$ 50

Basis of Presentation and Accou

Basis of Presentation and Accounting Policies	3 Months Ended
	Mar. 31, 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 for 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 ending March 31, 2020. For available-for-sale debt securities, the updated guidance was applied prospectively. For financial instruments measured at amortized cost, the updated guidance was applied by a cumulative effect adjustment to the opening balance of retained earnings as of January 1, 2020, the beginning of the period of adoption. The adoption of this guidance resulted in the recognition of an after-tax cumulative effect adjustment of $43 million to reflect the impact of recognizing expected credit losses, as compared to incurred credit losses recognized under the previous guidance. This adjustment is primarily associated with structured settlements that are recorded as part of reinsurance recoverables. The cumulative effect adjustment decreased retained earnings as of January 1, 2020 and increased the allowance for estimated uncollectible reinsurance. 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 Maturities Some of the factors considered in assessing impairment of fixed maturities 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 maturities 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 maturities 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 maturities, 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 principle 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	3 Months Ended
	Mar. 31, 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 March 31, in millions) Business Insurance Bond & Specialty Insurance Personal Insurance Total Reportable Segments 2020 Premiums $ 3,864 $ 667 $ 2,698 $ 7,229 Net investment income 453 55 103 611 Fee income 102 — 6 108 Other revenues 31 5 22 58 Total segment revenues (1) $ 4,450 $ 727 $ 2,829 $ 8,006 Segment income (1) $ 289 $ 122 $ 336 $ 747 2019 Premiums $ 3,742 $ 606 $ 2,507 $ 6,855 Net investment income 427 56 99 582 Fee income 104 — 5 109 Other revenues 43 6 22 71 Total segment revenues (1) $ 4,316 $ 668 $ 2,633 $ 7,617 Segment income (1) $ 414 $ 138 $ 278 $ 830 _________________________________________________________ (1) Segment revenues for reportable business segments exclude net realized investment gains (losses). Segment income for reportable business segments equals net income excluding the after-tax impact of net realized investment gains (losses). Business Segment Reconciliations Three Months Ended (in millions) 2020 2019 Revenue reconciliation Earned premiums Business Insurance: Domestic: Workers’ compensation $ 899 $ 972 Commercial automobile 684 628 Commercial property 508 460 General liability 601 567 Commercial multi-peril 886 840 Other 12 8 Total Domestic 3,590 3,475 International 274 267 Total Business Insurance 3,864 3,742 Bond & Specialty Insurance: Domestic: Fidelity and surety 257 246 General liability 287 257 Other 58 52 Total Domestic 602 555 International 65 51 Total Bond & Specialty Insurance 667 606 Personal Insurance: Domestic: Automobile 1,351 1,297 Homeowners and Other 1,176 1,039 Total Domestic 2,527 2,336 International 171 171 Total Personal Insurance 2,698 2,507 Total earned premiums 7,229 6,855 Net investment income 611 582 Fee income 108 109 Other revenues 58 71 Total segment revenues 8,006 7,617 Other revenues — 1 Net realized investment gains (losses) (98 ) 53 Total revenues $ 7,908 $ 7,671 Income reconciliation, net of tax Total segment income $ 747 $ 830 Interest Expense and Other (1) (71 ) (75 ) Core income 676 755 Net realized investment gains (losses) (76 ) 41 Net income $ 600 $ 796 _________________________________________________________ (1) The primary component of Interest Expense and Other was after-tax interest expense of $66 million and $70 million for the three months ended March 31, 2020 and 2019 , respectively. (in millions) March 31, December 31, Asset reconciliation Business Insurance $ 83,525 $ 83,896 Bond & Specialty Insurance 8,690 8,599 Personal Insurance 16,666 17,015 Total assets by reportable segment 108,881 109,510 Other assets (1) 555 612 Total consolidated assets $ 109,436 $ 110,122 _________________________________________________________ (1) The primary components of other assets at both March 31, 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

Investments	3 Months Ended
	Mar. 31, 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 March 31, 2020, in millions) Gains Losses U.S. Treasury securities and obligations of U.S. government and government agencies and authorities $ 2,003 $ — $ 53 $ 1 $ 2,055 Obligations of states, municipalities and political subdivisions: Local general obligation 15,893 — 907 9 16,791 Revenue 10,158 — 593 3 10,748 State general obligation 1,149 — 65 — 1,214 Pre-refunded 2,166 — 89 — 2,255 Total obligations of states, municipalities and political subdivisions 29,366 — 1,654 12 31,008 Debt securities issued by foreign governments 1,016 — 24 — 1,040 Mortgage-backed securities, collateralized mortgage obligations and pass-through securities 3,165 — 147 5 3,307 All other corporate bonds 30,034 4 816 405 30,441 Redeemable preferred stock 46 — — — 46 Total $ 65,630 $ 4 $ 2,694 $ 423 $ 67,897 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 $2.26 billion and $2.06 billion at March 31, 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 $388 million and $769 million during the three months ended March 31, 2020 and 2019 , respectively. Gross gains of $15 million and $21 million and gross losses of $1 million and $4 million were realized on those sales during the three months ended March 31, 2020 and 2019 , respectively. Equity Securities The cost and fair value of investments in equity securities were as follows: Fair (at March 31, 2020, in millions) Cost Gross Gains Gross Losses Value Public common stock $ 339 $ 9 $ 43 $ 305 Non-redeemable preferred stock 33 6 2 37 Total $ 372 $ 15 $ 45 $ 342 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 three months ended March 31, 2020 and 2019, the Company recognized $(79) million and $39 million of net gains (losses) on equity securities still held as of March 31, 2020 and 2019 , respectively. Net realized investment losses on equity securities still held for the first quarter of 2020 were driven by the impact of changes in fair value attributable to the recent disruption 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 March 31, 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 March 31, 2020, in millions) Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses Fixed maturities U.S. Treasury securities and obligations of U.S. government and government agencies and authorities $ 71 $ 1 $ — $ — $ 71 $ 1 Obligations of states, municipalities and political subdivisions 703 12 — — 703 12 Debt securities issued by foreign governments 5 — — — 5 — Mortgage-backed securities, collateralized mortgage obligations and pass-through securities 431 5 19 — 450 5 All other corporate bonds 8,239 382 188 23 8,427 405 Redeemable preferred stock 31 — — — 31 — Total $ 9,480 $ 400 $ 207 $ 23 $ 9,687 $ 423 Less than 12 months 12 months or longer Total (at December 31, 2019, in millions) Fair Gross Fair Gross Fair Gross Unrealized Losses Fixed maturities U.S. Treasury securities and obligations of U.S. government and government agencies and authorities $ 5 $ — $ 193 $ — $ 198 $ — Obligations of states, municipalities and political subdivisions 668 6 12 — 680 6 Debt securities issued by foreign governments 257 1 147 1 404 2 Mortgage-backed securities, collateralized mortgage obligations and pass-through securities 399 2 131 1 530 3 All other corporate bonds 1,571 10 662 8 2,233 18 Total $ 2,900 $ 19 $ 1,145 $ 10 $ 4,045 $ 29 At March 31, 2020 , the Company had $107 million of unrealized investment losses on fixed maturity investments for which fair value has been less than 80% of amortized cost for a continuous period of three months or less. The Company determined that the unrealized losses on these securities were due to non-credit factors. These unrealized investment losses were related to "All other corporate bonds" in the foregoing table and represented less than 1% of the Company's fixed maturity investment portfolio and less than 1% of shareholders' equity at March 31, 2020. Additionally, the Company currently does not intend to and is not required to sell these investments prior to an anticipated recovery in value. Impairment Charges The following table represents a reconciliation of the beginning and ending balances of the allowance for expected credit losses on fixed maturities classified as available for sale: Fixed Maturities (for the three months ended March 31, 2020 in millions) Mortgage-Backed Securities, Collateralized Mortgage Obligations and Pass-Through Securities All Other Corporate Bonds Total Balance, Beginning of Period $ — $ — $ — Additions for expected credit losses on securities where no credit losses were previously recognized — 4 4 Additions (reductions) for expected credit losses on securities where credit losses were previously recognized — — — Reductions due to sales/defaults of credit-impaired securities — — — Reductions for impairments of securities which the Company intends to sell or more likely than not will be required to sell (1) — — — Balance, End of Period $ — $ 4 $ 4 (1) Credit impairment charges recognized in net realized investment gains (losses) for the three months ended March 31, 2020 included $12 million of credit losses on securities which the Company intends to sell. An allowance for expected credit losses was not previously recorded for these securities. Total credit impairment charges included in net realized investment gains (losses) in the consolidated statement of income were $16 million and $1 million for the three months ended March 31, 2020 and 2019 , respectively. Credit losses for the three months ended March 31, 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 dates. Other Investments Included in other investments are private equity partnerships, hedge funds and real estate partnerships that are accounted for under the equity method of accounting and typically report their financial statement information to the Company one month to three months

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 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 March 31, 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 $94 million and $73 million at March 31, 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 $0 million and $28 million at March 31, 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 March 31, 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 March 31, 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 $ 2,055 $ 2,055 $ — $ — Obligations of states, municipalities and political subdivisions 31,008 — 30,996 12 Debt securities issued by foreign governments 1,040 — 1,040 — Mortgage-backed securities, collateralized mortgage obligations and pass-through securities 3,307 — 3,307 — All other corporate bonds 30,441 2 30,357 82 Redeemable preferred stock 46 3 43 — Total fixed maturities 67,897 2,060 65,743 94 Equity securities Public common stock 305 305 — — Non-redeemable preferred stock 37 15 22 — Total equity securities 342 320 22 — Other investments 33 12 — 21 Total $ 68,272 $ 2,392 $ 65,765 $ 115 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 three months ended March 31, 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 March 31, 2020, in millions) Carrying Value Fair Value Level 1 Level 2 Level 3 Financial assets Short-term securities $ 4,033 $ 4,033 $ 906 $ 3,076 $ 51 Financial liabilities Debt $ 6,459 $ 8,026 $ — $ 8,026 $ — Commercial paper $ 100 $ 100 $ — $ 100 $ — (at December 31, 2019, in millions) Carrying Value Fair Value Level 1 Level 2 Level 3 Financial assets Short-term securities $ 4,943 $ 4,943 $ 685 $ 4,204 $ 54 Financial liabilities Debt $ 6,458 $ 8,049 $ — $ 8,049 $ — Commercial paper $ 100 $ 100 $ — $ 100 $ — The Company had no material assets or liabilities that were measured at fair value on a non-recurring basis during the three months ended March 31, 2020 or year ended December 31, 2019 .

Allowance for Expected Credit L

Allowance for Expected Credit Losses	3 Months Ended
	Mar. 31, 2020
Credit Loss [Abstract]
Allowance for Expected Credit Losses	ALLOWANCE FOR EXPECTED CREDIT LOSSES Premiums Receivable The following table presents the balances of premiums receivable, net of the allowance for expected credit losses, at March 31, 2020 and January 1, 2020, and changes in the allowance for expected credit losses for the three months ended March 31, 2020 . (in millions) Premiums Receivable, Net of Allowance for Expected Credit Losses Allowance for Expected Credit Losses Balance, January 1, 2020 $ 7,909 $ 49 Current period change for expected credit losses 43 Write-offs of uncollectible premiums receivable 14 Balance, March 31, 2020 $ 8,202 $ 78 Reinsurance Recoverables The following table presents the balances of reinsurance recoverables, net of the allowance for estimated uncollectible reinsurance, at March 31, 2020 and January 1, 2020, and changes in the allowance for estimated uncollectible reinsurance for the three months ended March 31, 2020 . (in millions) Reinsurance Recoverables, Net of Allowance for Estimated Uncollectible Reinsurance Allowance for Estimated Uncollectible Reinsurance Balance, January 1, 2020 $ 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 4 Write-offs of uncollectible reinsurance recoverables — Balance, March 31, 2020 $ 8,152 $ 149 Of the total reinsurance recoverables at March 31, 2020 , after deducting mandatory pools and associations and before allowances for estimated uncollectible reinsurance, $5.58 billion , or 87% , 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 13% 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 6% 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 table presents the balances of contractholder receivables, net of the allowance for expected credit losses, at March 31, 2020 and January 1, 2020, and changes in the allowance for expected credit losses for the three months ended March 31, 2020 . (in millions) Contractholder Receivables, Net of Allowance for Expected Credit Losses Allowance for Expected Credit Losses Balance, January 1, 2020 $ 4,599 $ 20 Current period change for expected credit losses — Write-offs of uncollectible contractholder receivables — Balance, March 31, 2020 $ 4,634 $ 20

Goodwill and Other Intangible A

Goodwill and Other Intangible Assets	3 Months Ended
	Mar. 31, 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) March 31, December 31, Business Insurance $ 2,570 $ 2,601 Bond & Specialty Insurance 550 550 Personal Insurance 769 784 Other 26 26 Total $ 3,915 $ 3,961 Other Intangible Assets The following tables present a summary of the Company’s other intangible assets by major asset class. (at March 31, 2020, in millions) Gross Carrying Amount Accumulated Amortization Net Subject to amortization Customer-related $ 94 $ 22 $ 72 Contract-based (1) 204 180 24 Total subject to amortization 298 202 96 Not subject to amortization 226 — 226 Total $ 524 $ 202 $ 322 (at December 31, 2019, in millions) Gross Carrying Amount Accumulated Amortization Net Subject to amortization Customer-related $ 99 $ 21 $ 78 Contract-based (1) 205 179 26 Total subject to amortization 304 200 104 Not subject to amortization 226 — 226 Total $ 530 $ 200 $ 330 _________________________________________________________ (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 March 31, 2020 and 2019 . Amortization expense for all intangible assets subject to amortization is estimated to be $10 million for the remainder of 2020 , $13 million in 2021 , $12 million in 2022 , $12 million in 2023 and $11 million in 2024 . Amortization expense for intangible assets arising from insurance contracts acquired in a business combination is estimated to be $4 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	3 Months Ended
	Mar. 31, 2020
Insurance Loss Reserves [Abstract]
Insurance Claim Reserves	INSURANCE CLAIM RESERVES Claims and claim adjustment expense reserves were as follows: (in millions) March 31, December 31, Property-casualty $ 51,944 $ 51,836 Accident and health 13 13 Total $ 51,957 $ 51,849 The following table presents a reconciliation of beginning and ending property casualty reserve balances for claims and claim adjustment expenses: Three Months Ended (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 4,763 4,435 Estimated decrease in claims and claim adjustment expenses for claims arising in prior years (3 ) (16 ) Total increases 4,760 4,419 Claims and claim adjustment expense payments for claims arising in: Current year 947 970 Prior years 3,439 3,320 Total payments 4,386 4,290 Unrealized foreign exchange (gain) loss (210 ) 41 Net reserves at end of period 44,018 42,641 Plus reinsurance recoverables on unpaid losses 7,926 8,063 Claims and claim adjustment expense reserves at end of period $ 51,944 $ 50,704 Gross claims and claim adjustment expense reserves at March 31, 2020 increased by $108 million from December 31, 2019 , primarily reflecting the impact of higher volumes of insured exposures and loss cost trends for the current accident year. Reinsurance recoverables on unpaid losses at March 31, 2020 decreased by $109 million from December 31, 2019 , primarily reflecting the $53 million cumulative effect of adoption of updated accounting guidance for credit losses at January 1, 2020 and cash collections in the first three months of 2020. 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, as well as the outcome of any related legal challenges, 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. The Company continues to evaluate the impact of recent developments on the estimated realizable value of its subrogation claims related to the 2017 and 2018 California wildfires. Recent developments include (i) the approval of Restructuring Support Agreements (RSAs) by the United States Bankruptcy Court reflecting the settlement of subrogation claims and individual wildfire victim claims against Pacific Gas & Electric Company (PG&E) and a settlement between bondholders and PG&E and (ii) PG&E reached agreement with the Governor of California to secure his support for PG&E's plan of reorganization and (iii) the ballots for voting have been sent to parties entitled to vote on PG&E's plan of reorganization and are due to be cast by May 15. The plan confirmation hearing is scheduled to begin May 27. The California Public Utilities Commission must provide regulatory approval for PG&E's plan of reorganization and is expected to issue its decision in the second quarter of 2020. The RSAs may be terminated if PG&E's plan of reorganization is not confirmed by June 30, 2020. Due to the risks and uncertainties associated with the PG&E bankruptcy and other factors, the Company has not yet recognized a subrogation benefit related to these claims. Prior Year Reserve Development The following disclosures regarding reserve development are on a “net of reinsurance” basis. For the three months ended March 31, 2020 and 2019 , estimated claims and claim adjustment expenses incurred included $3 million and $16 million , respectively, of net favorable development for claims arising in prior years, including $27 million and $51 million , respectively, of net favorable prior year reserve development, and $12 million of accretion of discount in each period that impacted the Company's results of operations. Business Insurance. Net favorable prior year reserve development in the first quarter of 2020 totaled $5 million , primarily driven 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 multiple accident years. Largely offset by: • Commercial automobile - higher than expected loss experience in the segment's domestic operations for recent accident years. Net unfavorable prior year reserve development in the first quarter of 2019 totaled $21 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, primarily for years prior to 2009, due to the enactment by New York State of the Child Victims Act on February 14, 2019; and • Commercial multi-peril - higher than expected loss experience in the segment's domestic operations primarily for recent accident years. Partially offset by: • Workers' compensation - better than expected loss experience in the segment's domestic operations for multiple accident years. Bond & Specialty Insurance. There was no net prior year reserve development in the first quarter of 2020 . Net favorable prior year reserve development in the first quarter of 2019 of $3 million was not significant. Personal Insurance. Net favorable prior year reserve development in the first quarter of 2020 totaled $22 million , primarily driven by better than expected loss experience in the segment's domestic operations in both the automobile and homeowners and other product lines for multiple accident years. Net favorable prior year reserve development in the first quarter of 2019 totaled $69 million , primarily driven by better than expected loss experience in the segment's domestic operations in the automobile product line for recent accident years.

Other Comprehensive Income and

Other Comprehensive Income and Accumulated Other Comprehensive Income	3 Months Ended
	Mar. 31, 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 ended March 31, 2020. Changes in Net Unrealized Gains on Investment Securities (in millions) Having No Credit Losses Recognized in the Consolidated Statement of Income Having Credit Losses Recognized in the Consolidated Statement of Income Net Benefit Plan Assets and Obligations Recognized in Shareholders’ Equity Net Unrealized Foreign Currency Translation Total Accumulated Other Comprehensive Income (Loss) Balance, December 31, 2019 $ 2,057 $ 189 $ (846 ) $ (760 ) $ 640 Other comprehensive income (loss) (OCI) before reclassifications, net of tax (459 ) (4 ) 1 (246 ) (708 ) Amounts reclassified from AOCI, net of tax 2 — 17 — 19 Net OCI, current period (457 ) (4 ) 18 (246 ) (689 ) Balance, March 31, 2020 $ 1,600 $ 185 $ (828 ) $ (1,006 ) $ (49 ) The following table presents the pre-tax components of the Company’s other comprehensive income (loss) and the related income tax expense (benefit). Three Months Ended (in millions) 2020 2019 Changes in net unrealized gains on investment securities: Having no credit losses recognized in the consolidated statement of income $ (575 ) $ 1,416 Income tax expense (benefit) (118 ) 300 Net of taxes (457 ) 1,116 Having credit losses recognized in the consolidated statement of income (6 ) 5 Income tax expense (benefit) (2 ) 1 Net of taxes (4 ) 4 Net changes in benefit plan assets and obligations 23 12 Income tax expense 5 2 Net of taxes 18 10 Net changes in unrealized foreign currency translation (268 ) 50 Income tax expense (benefit) (22 ) 3 Net of taxes (246 ) 47 Total other comprehensive income (loss) (826 ) 1,483 Total income tax expense (benefit) (137 ) 306 Total other comprehensive income (loss), net of taxes $ (689 ) $ 1,177 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 (in millions) 2020 2019 Reclassification adjustments related to unrealized gains on investment securities: Having no credit losses recognized in the consolidated statement of income (1) $ 2 $ (16 ) Income tax expense (2) — (3 ) Net of taxes 2 (13 ) 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) 9 5 General and administrative expenses (3) 12 8 Total 21 13 Income tax benefit (2) 4 3 Net of taxes 17 10 Reclassification adjustment related to foreign currency translation (1) — — Income tax benefit (2) — — Net of taxes — — Total reclassifications 23 (3 ) Total income tax benefit 4 — Total reclassifications, net of taxes $ 19 $ (3 ) _________________________________________________________ (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.

Common Share Repurchases

Common Share Repurchases	3 Months Ended
	Mar. 31, 2020
Treasury Stock Transactions, Excluding Value of Shares Reissued [Abstract]
Common Share Repurchases	COMMON SHARE REPURCHASES During the three months ended March 31, 2020 , the Company repurchased 3.5 million shares under its share repurchase authorization, for a total cost of $425 million . The average cost per share repurchased was $123.09 . In addition, the Company acquired 0.3 million shares for a total cost of $46 million during the three months ended March 31, 2020 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 March 31, 2020 , the Company had $1.36 billion of capacity remaining under its share repurchase authorization.

Earnings per Share

Earnings per Share	3 Months Ended
	Mar. 31, 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 (in millions, except per share amounts) 2020 2019 Basic and Diluted Net income, as reported $ 600 $ 796 Participating share-based awards — allocated income (5 ) (5 ) Net income available to common shareholders — basic and diluted $ 595 $ 791 Common Shares Basic Weighted average shares outstanding 254.4 262.9 Diluted Weighted average shares outstanding 254.4 262.9 Weighted average effects of dilutive securities — stock options and performance shares 1.5 1.9 Total 255.9 264.8 Net Income per Common Share Basic $ 2.34 $ 3.01 Diluted $ 2.33 $ 2.99

Share-Based Incentive Compensat

Share-Based Incentive Compensation	3 Months Ended
	Mar. 31, 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 March 31, 2020 : Stock Options Number Weighted Average Exercise Price Weighted Average Contractual Life Remaining Aggregate Intrinsic Value ($ in millions) Vested at end of period (1) 7,743,262 $ 112.65 6.0 years $ 32 Exercisable at end of period 5,394,082 $ 104.00 4.7 years $ 32 _________________________________________________________ (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 $46 million and $45 million for the three months ended March 31, 2020 and 2019 , respectively. The related tax benefits recognized in the consolidated statement of income were $8 million for each of the three months ended March 31, 2020 and 2019 . The total unrecognized compensation cost related to all nonvested share-based incentive compensation awards at March 31, 2020 was $231 million , which is expected to be recognized over a weighted-average period of 2.1 years .

Pension Plans, Retirement Benef

Pension Plans, Retirement Benefits and Savings Plans	3 Months Ended
	Mar. 31, 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 for the Company’s pension and postretirement benefit plans recognized in the consolidated statement of income for the three months ended March 31, 2020 and 2019 . Pension Plans Postretirement Benefit Plans (for the three months ended March 31, in millions) 2020 2019 2020 2019 Net Periodic Benefit Cost: Service cost $ 33 $ 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 — — (2 ) (1 ) Net actuarial loss 23 14 — — Total non-service cost (benefit) (17 ) (20 ) (1 ) 1 Net periodic benefit cost $ 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 March 31, 2020 and 2019 . Pension Plans Postretirement Benefit Plans (for the three months ended March 31, in millions) 2020 2019 2020 2019 Service Cost: Claims and claim adjustment expenses $ 14 $ 12 $ — $ — General and administrative expenses 19 18 — — Total service cost 33 30 — — Non-Service Cost (Benefit): Claims and claim adjustment expenses (7 ) (8 ) — — General and administrative expenses (10 ) (12 ) (1 ) 1 Total non-service cost (benefit) (17 ) (20 ) (1 ) 1 Net periodic benefit cost $ 16 $ 10 $ (1 ) $ 1

Leases

Leases	3 Months Ended
	Mar. 31, 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 (in millions) 2020 2019 Lease cost Operating leases $ 24 $ 22 Short-term leases (1) — 4 Lease expense 24 26 Less: sublease income (2) — — Net lease cost $ 24 $ 26 Other information on operating leases Cash payments to settle a lease liability reported in cash flows $ 27 $ 24 Right-of-use assets obtained in exchange for new lease liabilities $ 14 $ 8 Weighted average discount rate 2.97 % 3.07 % Weighted average remaining lease term 5.0 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 $ 81 2021 94 2022 73 2023 54 2024 37 Thereafter 57 Total undiscounted lease payments 396 Less: present value adjustment 30 Operating lease liability $ 366

Contingencies, Commitments and

Contingencies, Commitments and Guarantees	3 Months Ended
	Mar. 31, 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 $1.68 billion and $1.66 billion at March 31, 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 March 31, 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 March 31, 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)	3 Months Ended
	Mar. 31, 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 for 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 ending March 31, 2020. For available-for-sale debt securities, the updated guidance was applied prospectively. For financial instruments measured at amortized cost, the updated guidance was applied by a cumulative effect adjustment to the opening balance of retained earnings as of January 1, 2020, the beginning of the period of adoption. The adoption of this guidance resulted in the recognition of an after-tax cumulative effect adjustment of $43 million to reflect the impact of recognizing expected credit losses, as compared to incurred credit losses recognized under the previous guidance. This adjustment is primarily associated with structured settlements that are recorded as part of reinsurance recoverables. The cumulative effect adjustment decreased retained earnings as of January 1, 2020 and increased the allowance for estimated uncollectible reinsurance. 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 Maturities Some of the factors considered in assessing impairment of fixed maturities 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 maturities 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 maturities 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 maturities, 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 principle 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)	3 Months Ended
	Mar. 31, 2020
Segment Reporting [Abstract]
Company's revenues and income by segment [Table Text Block]	(For the three months ended March 31, in millions) Business Insurance Bond & Specialty Insurance Personal Insurance Total Reportable Segments 2020 Premiums $ 3,864 $ 667 $ 2,698 $ 7,229 Net investment income 453 55 103 611 Fee income 102 — 6 108 Other revenues 31 5 22 58 Total segment revenues (1) $ 4,450 $ 727 $ 2,829 $ 8,006 Segment income (1) $ 289 $ 122 $ 336 $ 747 2019 Premiums $ 3,742 $ 606 $ 2,507 $ 6,855 Net investment income 427 56 99 582 Fee income 104 — 5 109 Other revenues 43 6 22 71 Total segment revenues (1) $ 4,316 $ 668 $ 2,633 $ 7,617 Segment income (1) $ 414 $ 138 $ 278 $ 830 _________________________________________________________ (1) Segment revenues for reportable business segments exclude net realized investment gains (losses). Segment income for reportable business segments equals net income excluding the after-tax impact of net realized investment gains (losses).
Business segment reconciliations of revenue and income, net of tax [Table Text Block]	Three Months Ended (in millions) 2020 2019 Revenue reconciliation Earned premiums Business Insurance: Domestic: Workers’ compensation $ 899 $ 972 Commercial automobile 684 628 Commercial property 508 460 General liability 601 567 Commercial multi-peril 886 840 Other 12 8 Total Domestic 3,590 3,475 International 274 267 Total Business Insurance 3,864 3,742 Bond & Specialty Insurance: Domestic: Fidelity and surety 257 246 General liability 287 257 Other 58 52 Total Domestic 602 555 International 65 51 Total Bond & Specialty Insurance 667 606 Personal Insurance: Domestic: Automobile 1,351 1,297 Homeowners and Other 1,176 1,039 Total Domestic 2,527 2,336 International 171 171 Total Personal Insurance 2,698 2,507 Total earned premiums 7,229 6,855 Net investment income 611 582 Fee income 108 109 Other revenues 58 71 Total segment revenues 8,006 7,617 Other revenues — 1 Net realized investment gains (losses) (98 ) 53 Total revenues $ 7,908 $ 7,671 Income reconciliation, net of tax Total segment income $ 747 $ 830 Interest Expense and Other (1) (71 ) (75 ) Core income 676 755 Net realized investment gains (losses) (76 ) 41 Net income $ 600 $ 796 _________________________________________________________ (1) The primary component of Interest Expense and Other was after-tax interest expense of $66 million and $70 million for the three months ended March 31, 2020 and 2019
Asset reconciliation [Table Text Block]	(in millions) March 31, December 31, Asset reconciliation Business Insurance $ 83,525 $ 83,896 Bond & Specialty Insurance 8,690 8,599 Personal Insurance 16,666 17,015 Total assets by reportable segment 108,881 109,510 Other assets (1) 555 612 Total consolidated assets $ 109,436 $ 110,122 _________________________________________________________ (1) The primary components of other assets at both March 31, 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)	3 Months Ended
	Mar. 31, 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 March 31, 2020, in millions) Gains Losses U.S. Treasury securities and obligations of U.S. government and government agencies and authorities $ 2,003 $ — $ 53 $ 1 $ 2,055 Obligations of states, municipalities and political subdivisions: Local general obligation 15,893 — 907 9 16,791 Revenue 10,158 — 593 3 10,748 State general obligation 1,149 — 65 — 1,214 Pre-refunded 2,166 — 89 — 2,255 Total obligations of states, municipalities and political subdivisions 29,366 — 1,654 12 31,008 Debt securities issued by foreign governments 1,016 — 24 — 1,040 Mortgage-backed securities, collateralized mortgage obligations and pass-through securities 3,165 — 147 5 3,307 All other corporate bonds 30,034 4 816 405 30,441 Redeemable preferred stock 46 — — — 46 Total $ 65,630 $ 4 $ 2,694 $ 423 $ 67,897 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 March 31, 2020, in millions) Cost Gross Gains Gross Losses Value Public common stock $ 339 $ 9 $ 43 $ 305 Non-redeemable preferred stock 33 6 2 37 Total $ 372 $ 15 $ 45 $ 342 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 March 31, 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 March 31, 2020, in millions) Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses Fixed maturities U.S. Treasury securities and obligations of U.S. government and government agencies and authorities $ 71 $ 1 $ — $ — $ 71 $ 1 Obligations of states, municipalities and political subdivisions 703 12 — — 703 12 Debt securities issued by foreign governments 5 — — — 5 — Mortgage-backed securities, collateralized mortgage obligations and pass-through securities 431 5 19 — 450 5 All other corporate bonds 8,239 382 188 23 8,427 405 Redeemable preferred stock 31 — — — 31 — Total $ 9,480 $ 400 $ 207 $ 23 $ 9,687 $ 423 Less than 12 months 12 months or longer Total (at December 31, 2019, in millions) Fair Gross Fair Gross Fair Gross Unrealized Losses Fixed maturities U.S. Treasury securities and obligations of U.S. government and government agencies and authorities $ 5 $ — $ 193 $ — $ 198 $ — Obligations of states, municipalities and political subdivisions 668 6 12 — 680 6 Debt securities issued by foreign governments 257 1 147 1 404 2 Mortgage-backed securities, collateralized mortgage obligations and pass-through securities 399 2 131 1 530 3 All other corporate bonds 1,571 10 662 8 2,233 18 Total $ 2,900 $ 19 $ 1,145 $ 10 $ 4,045 $ 29
Reconciliation of of the beginning and ending balances of the allowance for credit losses on fixed maturities classified as available-for-sale [Table Text Block]	The following table represents a reconciliation of the beginning and ending balances of the allowance for expected credit losses on fixed maturities classified as available for sale: Fixed Maturities (for the three months ended March 31, 2020 in millions) Mortgage-Backed Securities, Collateralized Mortgage Obligations and Pass-Through Securities All Other Corporate Bonds Total Balance, Beginning of Period $ — $ — $ — Additions for expected credit losses on securities where no credit losses were previously recognized — 4 4 Additions (reductions) for expected credit losses on securities where credit losses were previously recognized — — — Reductions due to sales/defaults of credit-impaired securities — — — Reductions for impairments of securities which the Company intends to sell or more likely than not will be required to sell (1) — — — Balance, End of Period $ — $ 4 $ 4 (1) Credit impairment charges recognized in net realized investment gains (losses) for the three months ended March 31, 2020 included $12 million of credit losses on 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)	3 Months Ended
	Mar. 31, 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 March 31, 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 $ 2,055 $ 2,055 $ — $ — Obligations of states, municipalities and political subdivisions 31,008 — 30,996 12 Debt securities issued by foreign governments 1,040 — 1,040 — Mortgage-backed securities, collateralized mortgage obligations and pass-through securities 3,307 — 3,307 — All other corporate bonds 30,441 2 30,357 82 Redeemable preferred stock 46 3 43 — Total fixed maturities 67,897 2,060 65,743 94 Equity securities Public common stock 305 305 — — Non-redeemable preferred stock 37 15 22 — Total equity securities 342 320 22 — Other investments 33 12 — 21 Total $ 68,272 $ 2,392 $ 65,765 $ 115 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 March 31, 2020, in millions) Carrying Value Fair Value Level 1 Level 2 Level 3 Financial assets Short-term securities $ 4,033 $ 4,033 $ 906 $ 3,076 $ 51 Financial liabilities Debt $ 6,459 $ 8,026 $ — $ 8,026 $ — Commercial paper $ 100 $ 100 $ — $ 100 $ — (at December 31, 2019, in millions) Carrying Value Fair Value Level 1 Level 2 Level 3 Financial assets Short-term securities $ 4,943 $ 4,943 $ 685 $ 4,204 $ 54 Financial liabilities Debt $ 6,458 $ 8,049 $ — $ 8,049 $ — Commercial paper $ 100 $ 100 $ — $ 100 $ —

Allowance for Expected Credit_2

Allowance for Expected Credit Losses (Tables)	3 Months Ended
	Mar. 31, 2020
Credit Loss [Abstract]
Changes in the allowance for expected credit losses on premiums receivable [Table Text Block]	The following table presents the balances of premiums receivable, net of the allowance for expected credit losses, at March 31, 2020 and January 1, 2020, and changes in the allowance for expected credit losses for the three months ended March 31, 2020 . (in millions) Premiums Receivable, Net of Allowance for Expected Credit Losses Allowance for Expected Credit Losses Balance, January 1, 2020 $ 7,909 $ 49 Current period change for expected credit losses 43 Write-offs of uncollectible premiums receivable 14 Balance, March 31, 2020 $ 8,202 $ 78
Changes in the allowance for estimated uncollectible reinsurance [Table Text Block]	The following table presents the balances of reinsurance recoverables, net of the allowance for estimated uncollectible reinsurance, at March 31, 2020 and January 1, 2020, and changes in the allowance for estimated uncollectible reinsurance for the three months ended March 31, 2020 . (in millions) Reinsurance Recoverables, Net of Allowance for Estimated Uncollectible Reinsurance Allowance for Estimated Uncollectible Reinsurance Balance, January 1, 2020 $ 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 4 Write-offs of uncollectible reinsurance recoverables — Balance, March 31, 2020 $ 8,152 $ 149
Changes in the allowance for expected credit losses on contractholder receivables [Table Text Block]	The following table presents the balances of contractholder receivables, net of the allowance for expected credit losses, at March 31, 2020 and January 1, 2020, and changes in the allowance for expected credit losses for the three months ended March 31, 2020 . (in millions) Contractholder Receivables, Net of Allowance for Expected Credit Losses Allowance for Expected Credit Losses Balance, January 1, 2020 $ 4,599 $ 20 Current period change for expected credit losses — Write-offs of uncollectible contractholder receivables — Balance, March 31, 2020 $ 4,634 $ 20

Goodwill and Other Intangible_2

Goodwill and Other Intangible Assets (Tables)	3 Months Ended
	Mar. 31, 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) March 31, December 31, Business Insurance $ 2,570 $ 2,601 Bond & Specialty Insurance 550 550 Personal Insurance 769 784 Other 26 26 Total $ 3,915 $ 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 March 31, 2020, in millions) Gross Carrying Amount Accumulated Amortization Net Subject to amortization Customer-related $ 94 $ 22 $ 72 Contract-based (1) 204 180 24 Total subject to amortization 298 202 96 Not subject to amortization 226 — 226 Total $ 524 $ 202 $ 322 (at December 31, 2019, in millions) Gross Carrying Amount Accumulated Amortization Net Subject to amortization Customer-related $ 99 $ 21 $ 78 Contract-based (1) 205 179 26 Total subject to amortization 304 200 104 Not subject to amortization 226 — 226 Total $ 530 $ 200 $ 330 _________________________________________________________ (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 March 31, 2020, in millions) Gross Carrying Amount Accumulated Amortization Net Subject to amortization Customer-related $ 94 $ 22 $ 72 Contract-based (1) 204 180 24 Total subject to amortization 298 202 96 Not subject to amortization 226 — 226 Total $ 524 $ 202 $ 322 (at December 31, 2019, in millions) Gross Carrying Amount Accumulated Amortization Net Subject to amortization Customer-related $ 99 $ 21 $ 78 Contract-based (1) 205 179 26 Total subject to amortization 304 200 104 Not subject to amortization 226 — 226 Total $ 530 $ 200 $ 330 _________________________________________________________ (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)	3 Months Ended
	Mar. 31, 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) March 31, December 31, Property-casualty $ 51,944 $ 51,836 Accident and health 13 13 Total $ 51,957 $ 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: Three Months Ended (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 4,763 4,435 Estimated decrease in claims and claim adjustment expenses for claims arising in prior years (3 ) (16 ) Total increases 4,760 4,419 Claims and claim adjustment expense payments for claims arising in: Current year 947 970 Prior years 3,439 3,320 Total payments 4,386 4,290 Unrealized foreign exchange (gain) loss (210 ) 41 Net reserves at end of period 44,018 42,641 Plus reinsurance recoverables on unpaid losses 7,926 8,063 Claims and claim adjustment expense reserves at end of period $ 51,944 $ 50,704

Other Comprehensive Income an_2

Other Comprehensive Income and Accumulated Other Comprehensive Income (Tables)	3 Months Ended
	Mar. 31, 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 ended March 31, 2020. Changes in Net Unrealized Gains on Investment Securities (in millions) Having No Credit Losses Recognized in the Consolidated Statement of Income Having Credit Losses Recognized in the Consolidated Statement of Income Net Benefit Plan Assets and Obligations Recognized in Shareholders’ Equity Net Unrealized Foreign Currency Translation Total Accumulated Other Comprehensive Income (Loss) Balance, December 31, 2019 $ 2,057 $ 189 $ (846 ) $ (760 ) $ 640 Other comprehensive income (loss) (OCI) before reclassifications, net of tax (459 ) (4 ) 1 (246 ) (708 ) Amounts reclassified from AOCI, net of tax 2 — 17 — 19 Net OCI, current period (457 ) (4 ) 18 (246 ) (689 ) Balance, March 31, 2020 $ 1,600 $ 185 $ (828 ) $ (1,006 ) $ (49 )
Pre-tax components of other comprehensive income (loss) and the related income tax expense (benefit) for each component [Table Text Block]	The following table presents the pre-tax components of the Company’s other comprehensive income (loss) and the related income tax expense (benefit). Three Months Ended (in millions) 2020 2019 Changes in net unrealized gains on investment securities: Having no credit losses recognized in the consolidated statement of income $ (575 ) $ 1,416 Income tax expense (benefit) (118 ) 300 Net of taxes (457 ) 1,116 Having credit losses recognized in the consolidated statement of income (6 ) 5 Income tax expense (benefit) (2 ) 1 Net of taxes (4 ) 4 Net changes in benefit plan assets and obligations 23 12 Income tax expense 5 2 Net of taxes 18 10 Net changes in unrealized foreign currency translation (268 ) 50 Income tax expense (benefit) (22 ) 3 Net of taxes (246 ) 47 Total other comprehensive income (loss) (826 ) 1,483 Total income tax expense (benefit) (137 ) 306 Total other comprehensive income (loss), net of taxes $ (689 ) $ 1,177
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 (in millions) 2020 2019 Reclassification adjustments related to unrealized gains on investment securities: Having no credit losses recognized in the consolidated statement of income (1) $ 2 $ (16 ) Income tax expense (2) — (3 ) Net of taxes 2 (13 ) 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) 9 5 General and administrative expenses (3) 12 8 Total 21 13 Income tax benefit (2) 4 3 Net of taxes 17 10 Reclassification adjustment related to foreign currency translation (1) — — Income tax benefit (2) — — Net of taxes — — Total reclassifications 23 (3 ) Total income tax benefit 4 — Total reclassifications, net of taxes $ 19 $ (3 ) _________________________________________________________ (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)	3 Months Ended
	Mar. 31, 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 (in millions, except per share amounts) 2020 2019 Basic and Diluted Net income, as reported $ 600 $ 796 Participating share-based awards — allocated income (5 ) (5 ) Net income available to common shareholders — basic and diluted $ 595 $ 791 Common Shares Basic Weighted average shares outstanding 254.4 262.9 Diluted Weighted average shares outstanding 254.4 262.9 Weighted average effects of dilutive securities — stock options and performance shares 1.5 1.9 Total 255.9 264.8 Net Income per Common Share Basic $ 2.34 $ 3.01 Diluted $ 2.33 $ 2.99

Share-Based Incentive Compens_2

Share-Based Incentive Compensation (Table)	3 Months Ended
	Mar. 31, 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 March 31, 2020 : Stock Options Number Weighted Average Exercise Price Weighted Average Contractual Life Remaining Aggregate Intrinsic Value ($ in millions) Vested at end of period (1) 7,743,262 $ 112.65 6.0 years $ 32 Exercisable at end of period 5,394,082 $ 104.00 4.7 years $ 32 _________________________________________________________ (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)	3 Months Ended
	Mar. 31, 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 for the Company’s pension and postretirement benefit plans recognized in the consolidated statement of income for the three months ended March 31, 2020 and 2019 . Pension Plans Postretirement Benefit Plans (for the three months ended March 31, in millions) 2020 2019 2020 2019 Net Periodic Benefit Cost: Service cost $ 33 $ 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 — — (2 ) (1 ) Net actuarial loss 23 14 — — Total non-service cost (benefit) (17 ) (20 ) (1 ) 1 Net periodic benefit cost $ 16 $ 10 $ (1 ) $ 1
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 March 31, 2020 and 2019 . Pension Plans Postretirement Benefit Plans (for the three months ended March 31, in millions) 2020 2019 2020 2019 Service Cost: Claims and claim adjustment expenses $ 14 $ 12 $ — $ — General and administrative expenses 19 18 — — Total service cost 33 30 — — Non-Service Cost (Benefit): Claims and claim adjustment expenses (7 ) (8 ) — — General and administrative expenses (10 ) (12 ) (1 ) 1 Total non-service cost (benefit) (17 ) (20 ) (1 ) 1 Net periodic benefit cost $ 16 $ 10 $ (1 ) $ 1

Leases (Tables)

Leases (Tables)	3 Months Ended
	Mar. 31, 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 (in millions) 2020 2019 Lease cost Operating leases $ 24 $ 22 Short-term leases (1) — 4 Lease expense 24 26 Less: sublease income (2) — — Net lease cost $ 24 $ 26 Other information on operating leases Cash payments to settle a lease liability reported in cash flows $ 27 $ 24 Right-of-use assets obtained in exchange for new lease liabilities $ 14 $ 8 Weighted average discount rate 2.97 % 3.07 % Weighted average remaining lease term 5.0 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.
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 $ 81 2021 94 2022 73 2023 54 2024 37 Thereafter 57 Total undiscounted lease payments 396 Less: present value adjustment 30 Operating lease liability $ 366

Basis of Presentation and Acc_3

Basis of Presentation and Accounting Policies (Details) - USD ($) $ in Millions	Mar. 31, 2020	Jan. 01, 2020	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018
New Accounting Pronouncements
Shareholders' equity	$ (25,204)		$ (25,943)	$ (24,340)
Retained earnings [Member]
New Accounting Pronouncements
Shareholders' equity	$ (37,325)		(36,977)	$ (35,795)	$ (35,204)
Accounting Standards Update 2016-13 [Member] | 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
	Mar. 31, 2020USD ($)segment	Mar. 31, 2019USD ($)
Segment reporting information
Number of reportable business segments | segment	3
Premiums	$ 7,229	$ 6,855
Net investment income	611	582
Fee income	108	109
Other revenues	58	72
Net realized investment gains (losses)	(98)	53
Total revenues	7,908	7,671
Core income (loss)	676	755
Net realized investment gains (losses), net of tax	(76)	41
Net income	600	796
Reportable Segments [Member]
Segment reporting information
Premiums	7,229	6,855
Net investment income	611	582
Fee income	108	109
Other revenues	58	71
Total segment revenues	8,006	7,617
Core income (loss)	747	830
Reportable Segments [Member] | Business Insurance [Member]
Segment reporting information
Premiums	3,864	3,742
Net investment income	453	427
Fee income	102	104
Other revenues	31	43
Total segment revenues	4,450	4,316
Core income (loss)	289	414
Reportable Segments [Member] | Business Insurance [Member] | Domestic [Member]
Segment reporting information
Premiums	3,590	3,475
Reportable Segments [Member] | Business Insurance [Member] | Domestic [Member] | Workers' compensation [Member]
Segment reporting information
Premiums	899	972
Reportable Segments [Member] | Business Insurance [Member] | Domestic [Member] | Automobile [Member]
Segment reporting information
Premiums	684	628
Reportable Segments [Member] | Business Insurance [Member] | Domestic [Member] | Commercial property [Member]
Segment reporting information
Premiums	508	460
Reportable Segments [Member] | Business Insurance [Member] | Domestic [Member] | General liability [Member]
Segment reporting information
Premiums	601	567
Reportable Segments [Member] | Business Insurance [Member] | Domestic [Member] | Commercial multi-peril [Member]
Segment reporting information
Premiums	886	840
Reportable Segments [Member] | Business Insurance [Member] | Domestic [Member] | Other [Member]
Segment reporting information
Premiums	12	8
Reportable Segments [Member] | Business Insurance [Member] | International [Member]
Segment reporting information
Premiums	274	267
Reportable Segments [Member] | Bond & Specialty Insurance [Member]
Segment reporting information
Premiums	667	606
Net investment income	55	56
Fee income	0	0
Other revenues	5	6
Total segment revenues	727	668
Core income (loss)	122	138
Reportable Segments [Member] | Bond & Specialty Insurance [Member] | Domestic [Member]
Segment reporting information
Premiums	602	555
Reportable Segments [Member] | Bond & Specialty Insurance [Member] | Domestic [Member] | General liability [Member]
Segment reporting information
Premiums	287	257
Reportable Segments [Member] | Bond & Specialty Insurance [Member] | Domestic [Member] | Fidelity and surety [Member]
Segment reporting information
Premiums	257	246
Reportable Segments [Member] | Bond & Specialty Insurance [Member] | Domestic [Member] | Other [Member]
Segment reporting information
Premiums	58	52
Reportable Segments [Member] | Bond & Specialty Insurance [Member] | International [Member]
Segment reporting information
Premiums	65	51
Reportable Segments [Member] | Personal Insurance [Member]
Segment reporting information
Premiums	2,698	2,507
Net investment income	103	99
Fee income	6	5
Other revenues	22	22
Total segment revenues	2,829	2,633
Core income (loss)	336	278
Reportable Segments [Member] | Personal Insurance [Member] | Domestic [Member]
Segment reporting information
Premiums	2,527	2,336
Reportable Segments [Member] | Personal Insurance [Member] | Domestic [Member] | Automobile [Member]
Segment reporting information
Premiums	1,351	1,297
Reportable Segments [Member] | Personal Insurance [Member] | Domestic [Member] | Homeowners and Other [Member]
Segment reporting information
Premiums	1,176	1,039
Reportable Segments [Member] | Personal Insurance [Member] | International [Member]
Segment reporting information
Premiums	171	171
Other [Member]
Segment reporting information
Other revenues	0	1
Core income (loss)	(71)	(75)
After-tax interest expense	$ 66	$ 70

Segment Information (Details) -

Segment Information (Details) - Assets by Segment - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Assets by segment
Total assets	$ 109,436	$ 110,122
Reportable Segments [Member]
Assets by segment
Total assets	108,881	109,510
Reportable Segments [Member] | Business Insurance [Member]
Assets by segment
Total assets	83,525	83,896
Reportable Segments [Member] | Bond & Specialty Insurance [Member]
Assets by segment
Total assets	8,690	8,599
Reportable Segments [Member] | Personal Insurance [Member]
Assets by segment
Total assets	16,666	17,015
Other assets [Member]
Assets by segment
Total assets	$ 555	$ 612

Investments (Details) - Investm

Investments (Details) - Investment Information, Debt Securities - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Investment disclosure details
Fixed maturities, amortized cost	$ 65,630		$ 65,281
Allowance for credit losses	4		0
Gross unrealized gains	2,694		2,882
Gross unrealized losses	423		29
Fixed maturities, at fair value	67,897		68,134
Proceeds from sales of fixed maturities classified as available for sale	388	$ 769
Gross realized gains	15	21
Gross realized losses	1	$ 4
U.S. Treasury securities and obligations of U.S. government and government agencies and authorities [Member]
Investment disclosure details
Fixed maturities, amortized cost	2,003		2,076
Allowance for credit losses	0
Gross unrealized gains	53		19
Gross unrealized losses	1		0
Fixed maturities, at fair value	2,055		2,095
Obligations of states, municipalities and political subdivisions [Member]
Investment disclosure details
Fixed maturities, amortized cost	29,366		28,356
Allowance for credit losses	0
Gross unrealized gains	1,654		1,567
Gross unrealized losses	12		6
Fixed maturities, at fair value	31,008		29,917
Obligations of states, municipalities and political subdivisions, local general obligation [Member]
Investment disclosure details
Fixed maturities, amortized cost	15,893		15,490
Allowance for credit losses	0
Gross unrealized gains	907		829
Gross unrealized losses	9		4
Fixed maturities, at fair value	16,791		16,315
Obligations of states, municipalities and political subdivisions, revenue [Member]
Investment disclosure details
Fixed maturities, amortized cost	10,158		9,731
Allowance for credit losses	0
Gross unrealized gains	593		586
Gross unrealized losses	3		2
Fixed maturities, at fair value	10,748		10,315
Obligations of states, municipalities and political subdivisions, state general obligation [Member]
Investment disclosure details
Fixed maturities, amortized cost	1,149		1,167
Allowance for credit losses	0
Gross unrealized gains	65		64
Gross unrealized losses	0		0
Fixed maturities, at fair value	1,214		1,231
Obligations of states, municipalities and political subdivisions, pre-refunded [Member]
Investment disclosure details
Fixed maturities, amortized cost	2,166		1,968
Allowance for credit losses	0
Gross unrealized gains	89		88
Gross unrealized losses	0		0
Fixed maturities, at fair value	2,255		2,056
Debt securities issued by foreign governments [Member]
Investment disclosure details
Fixed maturities, amortized cost	1,016		1,167
Allowance for credit losses	0
Gross unrealized gains	24		8
Gross unrealized losses	0		2
Fixed maturities, at fair value	1,040		1,173
Mortgage-backed securities, collateralized mortgage obligations and pass-through securities [Member]
Investment disclosure details
Fixed maturities, amortized cost	3,165		3,192
Allowance for credit losses	0		0
Gross unrealized gains	147		91
Gross unrealized losses	5		3
Fixed maturities, at fair value	3,307		3,280
All other corporate bonds [Member]
Investment disclosure details
Fixed maturities, amortized cost	30,034		30,442
Allowance for credit losses	4		0
Gross unrealized gains	816		1,195
Gross unrealized losses	405		18
Fixed maturities, at fair value	30,441		31,619
Redeemable preferred stock [Member]
Investment disclosure details
Fixed maturities, amortized cost	46		48
Allowance for credit losses	0
Gross unrealized gains	0		2
Gross unrealized losses	0		0
Fixed maturities, at fair value	$ 46		$ 50

Investments (Details) - Inves_2

Investments (Details) - Investment Information, Equity Securities - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Investment disclosure details
Equity securities, cost	$ 372		$ 376
Gross gains	15		52
Gross losses	45		3
Equity securities, at fair value	342		425
Net recognized gains (losses) on equity securities still held	(79)	$ 39
Public common stock [Member]
Investment disclosure details
Equity securities, cost	339		341
Gross gains	9		45
Gross losses	43		3
Equity securities, at fair value	305		383
Non-redeemable preferred stock [Member]
Investment disclosure details
Equity securities, cost	33		35
Gross gains	6		7
Gross losses	2		0
Equity securities, at fair value	$ 37		$ 42

Investments (Details) - Inves_3

Investments (Details) - Investment Information, Losses - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Investment disclosure details
Continuous unrealized loss position, less than 12 months, fair value	$ 9,480	$ 2,900
Continuous unrealized loss position, less than 12 months, gross unrealized losses	400	19
Continuous unrealized loss position, 12 months or longer, fair value	207	1,145
Continuous unrealized loss position, 12 months or longer, gross unrealized losses	23	10
Continuous unrealized loss position, total, fair value	9,687	4,045
Continuous unrealized loss position, total, gross unrealized losses	423	29
Unrealized investment losses on fixed maturity investments for which fair value is less than 80% of amortized cost, total	$ 107
Unrealized investment losses for securities for which fair value is less than 80% of amortized cost, as a percentage of the combined fixed maturity and equity security portfolios on a pre-tax basis (less than)	1.00%
Unrealized investment losses for securities for which fair value is less than 80% of amortized cost, as a percentage of shareholders' equity on an after-tax basis (less than)	1.00%
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	$ 71	5
Continuous unrealized loss position, less than 12 months, gross unrealized losses	1	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	71	198
Continuous unrealized loss position, total, gross unrealized losses	1	0
Obligations of states, municipalities and political subdivisions [Member]
Investment disclosure details
Continuous unrealized loss position, less than 12 months, fair value	703	668
Continuous unrealized loss position, less than 12 months, gross unrealized losses	12	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	703	680
Continuous unrealized loss position, total, gross unrealized losses	12	6
Debt securities issued by foreign governments [Member]
Investment disclosure details
Continuous unrealized loss position, less than 12 months, fair value	5	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	5	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	431	399
Continuous unrealized loss position, less than 12 months, gross unrealized losses	5	2
Continuous unrealized loss position, 12 months or longer, fair value	19	131
Continuous unrealized loss position, 12 months or longer, gross unrealized losses	0	1
Continuous unrealized loss position, total, fair value	450	530
Continuous unrealized loss position, total, gross unrealized losses	5	3
All other corporate bonds [Member]
Investment disclosure details
Continuous unrealized loss position, less than 12 months, fair value	8,239	1,571
Continuous unrealized loss position, less than 12 months, gross unrealized losses	382	10
Continuous unrealized loss position, 12 months or longer, fair value	188	662
Continuous unrealized loss position, 12 months or longer, gross unrealized losses	23	8
Continuous unrealized loss position, total, fair value	8,427	2,233
Continuous unrealized loss position, total, gross unrealized losses	405	$ 18
Unrealized investment losses on fixed maturity investments for which fair value is less than 80% of amortized cost for three months or less	107
Redeemable preferred stock [Member]
Investment disclosure details
Continuous unrealized loss position, less than 12 months, fair value	31
Continuous unrealized loss position, less than 12 months, gross unrealized losses	0
Continuous unrealized loss position, 12 months or longer, fair value	0
Continuous unrealized loss position, 12 months or longer, gross unrealized losses	0
Continuous unrealized loss position, total, fair value	31
Continuous unrealized loss position, total, gross unrealized losses	$ 0

Investments (Details) - Credit

Investments (Details) - Credit Loss Allowance - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Allowance for credit losses [Roll Forward]
Allowance for credit losses on fixed maturities classified as available-for-sale, balance, beginning of year	$ 0
Additions for credit losses on securities where no credit losses were previously recognized	4
Additions (reductions) for credit losses on securities where credit losses were previously recognized	0
Reductions due to sales/defaults of credit-impaired securities	0
Reductions for impairments of securities which the Company intends to sell or more likely than not will be required to sell	0
Allowance for credit losses on fixed maturities classified as available-for-sale, balance, end of period	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	12
Total credit impairment charges included in net realized investment gains (losses) in the consolidated statement of income	$ 16	$ 1
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%
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%
Mortgage-backed securities, collateralized mortgage obligations and pass-through securities [Member]
Allowance for credit losses [Roll Forward]
Allowance for credit losses on fixed maturities classified as available-for-sale, balance, beginning of year	$ 0
Additions for credit losses on securities where no credit losses were previously recognized	0
Additions (reductions) for credit losses on securities where credit losses were previously recognized	0
Reductions due to sales/defaults of credit-impaired securities	0
Reductions for impairments of securities which the Company intends to sell or more likely than not will be required to sell	0
Allowance for credit losses on fixed maturities classified as available-for-sale, balance, end of period	0
All other corporate bonds [Member]
Allowance for credit losses [Roll Forward]
Allowance for credit losses on fixed maturities classified as available-for-sale, balance, beginning of year	0
Additions for credit losses on securities where no credit losses were previously recognized	4
Additions (reductions) for credit losses on securities where credit losses were previously recognized	0
Reductions due to sales/defaults of credit-impaired securities	0
Reductions for impairments of securities which the Company intends to sell or more likely than not will be required to sell	0
Allowance for credit losses on fixed maturities classified as available-for-sale, balance, end of period	$ 4

Investments (Details) - Other I

Investments (Details) - Other Investments	3 Months Ended
	Mar. 31, 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	Mar. 31, 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	$ 94	$ 73
Fair value of the fixed maturities for which the Company received a broker quote	0	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	Mar. 31, 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	$ 68,272	$ 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	67,897	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	2,055	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	31,008	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	1,040	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	3,307	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	30,441	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	46	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	342	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	305	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	37	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	33	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	2,392	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	2,060	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	2,055	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	2	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	3	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	320	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	305	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	15	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	12	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	65,765	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	65,743	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	30,996	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	1,040	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	3,307	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	30,357	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	43	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	22	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	22	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	115	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	94	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	12	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	82	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	$ 21	$ 20

Fair Value Measurements (Deta_3

Fair Value Measurements (Details) - Financial Instruments - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Financial Instruments
Short-term securities	$ 4,033	$ 4,943
Carrying Value [Member]
Financial Instruments
Short-term securities	4,033	4,943
Debt	6,459	6,458
Commercial paper	100	100
Fair Value [Member]
Financial Instruments
Short-term securities	4,033	4,943
Debt	8,026	8,049
Commercial paper	100	100
Fair Value [Member] | Level 1 [Member]
Financial Instruments
Short-term securities	906	685
Debt	0	0
Commercial paper	0	0
Fair Value [Member] | Level 2 [Member]
Financial Instruments
Short-term securities	3,076	4,204
Debt	8,026	8,049
Commercial paper	100	100
Fair Value [Member] | Level 3 [Member]
Financial Instruments
Short-term securities	51	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 $ in Millions	3 Months Ended
	Mar. 31, 2020USD ($)
Credit Loss [Abstract]
Premiums receivable (net of allowance for expected credit losses), balance, beginning of year	$ 7,909
Premiums receivable (net of allowance for expected credit losses), balance, end of period	8,202
Premiums receivable, allowance for expected credit losses [Roll Forward]
Premiums receivable, allowance for expected credit losses, beginning balance	49
Current period change for expected credit losses	43
Write-offs of uncollectible premiums receivable	14
Premiums receivable, allowance for expected credit losses, ending balance	$ 78

Allowance for Expected Credit_4

Allowance for Expected Credit Losses (Details) - Changes in the Allowance for Estimated Uncollectible Reinsurance $ in Millions	3 Months Ended
	Mar. 31, 2020USD ($)
Reinsurance recoverables, allowance for uncollectible reinsurance
Reinsurance recoverables (net of allowance for estimated uncollectible reinsurance), balance, beginning of year	$ 8,235
Reinsurance recoverables (net of allowance for estimated uncollectible reinsurance), balance, end of period	8,152
Reinsurance recoverables, allowance for uncollectible reinsurance [Roll Forward]
Reinsurance recoverables, allowance for uncollectible reinsurance, beginning balance	92
Reinsurance recoverables, allowance for estimated uncollectible reinsurance	149
Current period change for estimated uncollectible reinsurance	4
Write-offs of uncollectible reinsurance recoverables	0
Reinsurance recoverables, allowance for uncollectible reinsurance, ending balance	149
Accounting Standards Update 2016-13 [Member] | 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	3 Months Ended
	Mar. 31, 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	$ 5,580
Concentration risk percentage	87.00%
Reinsurance Recoverables [Member] | Reinsurer Group Not Rated by A.M. Best [Member]
Reinsurance recoverables, credit quality indicator
Concentration risk percentage	13.00%
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	6.00%
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) $ in Millions	3 Months Ended
	Mar. 31, 2020USD ($)
Credit Loss [Abstract]
Contractholder receivables (net of the allowance for expected credit losses), balance, beginning of year	$ 4,599
Contractholder receivables (net of the allowance for expected credit losses), balance, end of period	4,634
Contractholder receivables, allowance for expected credit losses [Roll Forward]
Contractholder receivables, allowance for expected credit losses, beginning balance	20
Current period change for expected credit losses	0
Write-offs of uncollectible contractholder receivables	0
Contractholder receivables, allowance for expected credit losses, ending balance	$ 20

Goodwill and Other Intangible_3

Goodwill and Other Intangible Assets (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Goodwill by segment
Goodwill	$ 3,915	$ 3,961
Reportable Segments [Member] | Business Insurance [Member]
Goodwill by segment
Goodwill	2,570	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	769	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
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Other intangible assets by major asset class
Intangible assets subject to amortization, gross carrying amount	$ 298		$ 304
Intangible assets subject to amortization, accumulated amortization	202		200
Intangible assets subject to amortization, net	96		104
Intangible assets not subject to amortization	226		226
Total other intangible assets, gross carrying amount	524		530
Total other intangible assets, net	322		330
Amortization expense of intangible assets	4	$ 4
Estimated intangible asset amortization expense, remainder of 2020	10
Estimated intangible asset amortization expense, 2021	13
Estimated intangible asset amortization expense, 2022	12
Estimated intangible asset amortization expense, 2023	12
Estimated intangible asset amortization expense, 2024	11
Customer-related [Member]
Other intangible assets by major asset class
Intangible assets subject to amortization, gross carrying amount	94		99
Intangible assets subject to amortization, accumulated amortization	22		21
Intangible assets subject to amortization, net	72		78
Contract-based [Member]
Other intangible assets by major asset class
Intangible assets subject to amortization, gross carrying amount	204		205
Intangible assets subject to amortization, accumulated amortization	180		179
Intangible assets subject to amortization, net	24		$ 26
Insurance Contracts Acquired in Business Combination [Member]
Other intangible assets by major asset class
Estimated intangible asset amortization expense, remainder of 2020	4
Estimated intangible asset amortization expense, 2021	4
Estimated intangible asset amortization expense, 2022	3
Estimated intangible asset amortization expense, 2023	3
Estimated intangible asset amortization expense, 2024	$ 2

Insurance Claim Reserves (Detai

Insurance Claim Reserves (Details) - Reserve Detail for Claims and Claim Adjustment Expenses - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	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
Reinsurance recoverables, allowance for estimated uncollectible reinsurance	149		$ 92
Claims and claim adjustment expense reserves at end of period	51,957
Accounting Standards Update 2016-13 [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
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	4,763	4,435
Estimated decrease in claims and claim adjustment expenses for claims arising in prior years	(3)	(16)
Total increases	4,760	4,419
Claims and claim adjustment expense payments for claims arising in current year	947	970
Claims and claim adjustment expense payments for claims arising in prior years	3,439	3,320
Total payments	4,386	4,290
Unrealized foreign exchange (gain) loss	(210)	41
Net reserves at end of period	44,018	42,641
Reinsurance recoverables on unpaid losses	7,926	8,063
Claims and claim adjustment expense reserves at end of period	51,944	$ 50,704
Amount of increase in gross claims and claim adjustment expense reserves	108
Amount of decrease in reinsurance recoverables on unpaid losses	109
Property-casualty [Member] | Accounting Standards Update 2016-13 [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	$ 13

Insurance Claim Reserves (Det_2

Insurance Claim Reserves (Details) - Prior Year Reserve Development - Property-casualty [Member] - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
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	$ 3	$ 16
Net favorable (unfavorable) prior year reserve development impacting the Company's results of operations	27	51
Accretion expense	12	12
Business Insurance [Member]
Liability for claims and claim adjustment expense
Net favorable (unfavorable) prior year reserve development impacting the Company's results of operations	5	(21)
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
Personal Insurance [Member]
Liability for claims and claim adjustment expense
Net favorable (unfavorable) prior year reserve development impacting the Company's results of operations	$ 22	$ 69

Other Comprehensive Income an_3

Other Comprehensive Income and Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Accumulated other comprehensive income [Roll Forward]
Balance, beginning of year	$ 25,943
Other comprehensive income (loss), net of taxes	(689)	$ 1,177
Balance, end of period	25,204	24,340
Pre-tax components of other comprehensive income (loss) and related tax expense (benefit)
Other comprehensive income (loss) before income taxes	(826)	1,483
Income tax expense (benefit)	(137)	306
Other comprehensive income (loss), net of taxes	(689)	1,177
Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated other comprehensive income [Roll Forward]
Balance, beginning of year	640	(1,859)
Other comprehensive income (loss) before reclassifications	(708)
Amounts reclassified from accumulated other comprehensive income	19
Other comprehensive income (loss), net of taxes	(689)	1,177
Balance, end of period	(49)	(682)
Pre-tax components of other comprehensive income (loss) and related tax expense (benefit)
Other comprehensive income (loss) before income taxes	(826)	1,483
Income tax expense (benefit)	(137)	306
Other comprehensive income (loss), net of taxes	(689)	1,177
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	2,057
Other comprehensive income (loss) before reclassifications	(459)
Amounts reclassified from accumulated other comprehensive income	2
Other comprehensive income (loss), net of taxes	(457)	1,116
Balance, end of period	1,600
Pre-tax components of other comprehensive income (loss) and related tax expense (benefit)
Other comprehensive income (loss) before income taxes	(575)	1,416
Income tax expense (benefit)	(118)	300
Other comprehensive income (loss), net of taxes	(457)	1,116
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	189
Other comprehensive income (loss) before reclassifications	(4)
Amounts reclassified from accumulated other comprehensive income	0
Other comprehensive income (loss), net of taxes	(4)	4
Balance, end of period	185
Pre-tax components of other comprehensive income (loss) and related tax expense (benefit)
Other comprehensive income (loss) before income taxes	(6)	5
Income tax expense (benefit)	(2)	1
Other comprehensive income (loss), net of taxes	(4)	4
Net Benefit Plan Assets and Obligations Recognized in Shareholders' Equity [Member]
Accumulated other comprehensive income [Roll Forward]
Balance, beginning of year	(846)
Other comprehensive income (loss) before reclassifications	1
Amounts reclassified from accumulated other comprehensive income	17
Other comprehensive income (loss), net of taxes	18	10
Balance, end of period	(828)
Pre-tax components of other comprehensive income (loss) and related tax expense (benefit)
Other comprehensive income (loss) before income taxes	23	12
Income tax expense (benefit)	5	2
Other comprehensive income (loss), net of taxes	18	10
Net Unrealized Foreign Currency Translation [Member]
Accumulated other comprehensive income [Roll Forward]
Balance, beginning of year	(760)
Other comprehensive income (loss) before reclassifications	(246)
Amounts reclassified from accumulated other comprehensive income	0
Other comprehensive income (loss), net of taxes	(246)	47
Balance, end of period	(1,006)
Pre-tax components of other comprehensive income (loss) and related tax expense (benefit)
Other comprehensive income (loss) before income taxes	(268)	50
Income tax expense (benefit)	(22)	3
Other comprehensive income (loss), net of taxes	$ (246)	$ 47

Other Comprehensive Income an_4

Other Comprehensive Income and Accumulated Other Comprehensive Income (Details) - Reclassifications - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Reclassification Adjustment out of Accumulated Other Comprehensive Income
Reclassification adjustment impacting net realized investment gains on the income statement	$ 98	$ (53)
Reclassification adjustment impacting claims and claim adjustment expenses on the income statement	4,789	4,442
Reclassification adjustment impacting general and administrative expense on the income statement	1,137	1,057
Total reclassifications	(720)	(967)
Income tax (expense) benefit	(120)	(171)
Amounts reclassified from accumulated other comprehensive income, net of taxes	(600)	(796)
Accumulated Other Comprehensive Income (Loss) [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income
Total reclassifications	23	(3)
Income tax (expense) benefit	4	0
Amounts reclassified from accumulated other comprehensive income, net of taxes	19	(3)
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 on the income statement	2	(16)
Income tax (expense) benefit	0	(3)
Amounts reclassified from accumulated other comprehensive income, net of taxes	2	(13)
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 on the income statement	0	0
Income tax (expense) benefit	0	0
Amounts reclassified from accumulated other comprehensive income, net of taxes	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	9	5
Reclassification adjustment impacting general and administrative expense on the income statement	12	8
Total reclassifications	21	13
Income tax (expense) benefit	4	3
Amounts reclassified from accumulated other comprehensive income, net of taxes	17	10
Net Unrealized Foreign Currency Translation [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income
Reclassification adjustment impacting net realized investment gains on the income statement	0	0
Income tax (expense) benefit	0	0
Amounts reclassified from accumulated other comprehensive income, net of taxes	$ 0	$ 0

Common Share Repurchases (Detai

Common Share Repurchases (Details) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2020USD ($)$ / sharesshares
Treasury Stock Transactions, Excluding Value of Shares Reissued [Abstract]
Number of shares repurchased (in shares) | shares	3.5
Cost of shares repurchased	$ 425
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	0.3
Cost of shares acquired to cover tax withholding costs and exercise costs	$ 46
Remaining capacity under share repurchase authorization	$ 1,360

Earnings per Share (Details)

Earnings per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Earnings Per Share Reconciliation [Abstract]
Net income	$ 600	$ 796
Participating share-based awards — allocated income	(5)	(5)
Net income available to common shareholders -- basic	595	791
Net income available to common shareholders -- diluted	$ 595	$ 791
Weighted average shares outstanding, basic (in shares)	254.4	262.9
Weighted average effects of dilutive securities - stock options and performance shares (in shares)	1.5	1.9
Weighted average shares outstanding, diluted (in shares)	255.9	264.8
Net income per common share, basic (in dollars per share)	$ 2.34	$ 3.01
Net income per common share, diluted (in dollars per share)	$ 2.33	$ 2.99

Share-Based Incentive Compens_3

Share-Based Incentive Compensation (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Share-based Payment Arrangement [Abstract]
Stock options vested at end of period, number (in shares)	7,743,262
Stock options vested at end of period, weighted average exercise price (in dollars per share)	$ 112.65
Stock options vested at end of period, weighted average contractual life remaining (in years)	6 years
Stock options vested at end of period, aggregate intrinsic value	$ 32
Stock options exercisable at end of period, number (in shares)	5,394,082
Stock options exercisable at end of period, weighted average exercise price (in dollars per share)	$ 104
Stock options exercisable at end of period, weighted average contractual life remaining (in years)	4 years 8 months 12 days
Stock options exercisable at end of period, aggregate intrinsic value	$ 32
Total compensation cost recognized in earnings for all share-based incentive compensation awards	46	$ 45
Tax benefit recognized in earnings related to compensation costs	8	$ 8
Total unrecognized compensation cost related to all nonvested share-based incentive compensation awards	$ 231
Weighted-average period of recognition for unrecognized compensation cost (in years)	2 years 1 month 6 days

Pension Plans, Retirement Ben_3

Pension Plans, Retirement Benefits and Savings Plans (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Pension Plans [Member]
Defined benefit plan disclosure
Service cost	$ 33	$ 30
Interest cost on benefit obligation	29	35
Expected return on plan assets	(69)	(69)
Net periodic benefit cost, amortization of unrecognized prior service benefit	0	0
Net periodic benefit cost, amortization of unrecognized net actuarial loss	23	14
Total non-service cost (benefit)	(17)	(20)
Net periodic benefit cost	16	10
Pension Plans [Member] | Claims and claim adjustment expenses [Member]
Defined benefit plan disclosure
Service cost	14	12
Total non-service cost (benefit)	(7)	(8)
Pension Plans [Member] | General and administrative expenses [Member]
Defined benefit plan disclosure
Service cost	19	18
Total non-service cost (benefit)	(10)	(12)
Postretirement Benefit Plans [Member]
Defined benefit plan disclosure
Service cost	0	0
Interest cost on benefit obligation	1	2
Expected return on plan assets	0	0
Net periodic benefit cost, amortization of unrecognized prior service benefit	(2)	(1)
Net periodic benefit cost, amortization of unrecognized net actuarial loss	0	0
Total non-service cost (benefit)	(1)	1
Net periodic benefit cost	(1)	1
Postretirement Benefit Plans [Member] | Claims and claim adjustment expenses [Member]
Defined benefit plan disclosure
Service cost	0	0
Total non-service cost (benefit)	0	0
Postretirement Benefit Plans [Member] | General and administrative expenses [Member]
Defined benefit plan disclosure
Service cost	0	0
Total non-service cost (benefit)	$ (1)	$ 1

Leases (Details)

Leases (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Leases [Abstract]
Operating leases	$ 24	$ 22
Short-term leases	0	4
Lease expense	24	26
Less: sublease income	0	0
Net lease cost	24	26
Cash payments to settle a lease liability reported in cash flows	27	24
Right-of-use assets obtained in exchange for new lease liabilities	$ 14	$ 8
Weighted average discount rate (percent)	2.97%	3.07%
Weighted average remaining lease term (in years)	5 years	5 years 2 months 12 days

Leases (Details) - Contractual

Leases (Details) - Contractual Maturities of Lease Liabilities $ in Millions	Mar. 31, 2020USD ($)
Leases [Abstract]
Lease payments due, remainder of 2020	$ 81
Lease payments due, 2021	94
Lease payments due, 2022	73
Lease payments due, 2023	54
Lease payments due, 2024	37
Lease payments due, thereafter	57
Total undiscounted lease payments	396
Less: present value adjustment	30
Operating lease liability	$ 366

Contingencies, Commitments an_2

Contingencies, Commitments and Guarantees (Details) - Commitments - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Contingencies, Commitments and Guarantees [Abstract]
Unfunded commitments to private equity limited partnerships and real estate partnerships	$ 1,680	$ 1,660

Contingencies, Commitments an_3

Contingencies, Commitments and Guarantees (Details) - Guarantees $ in Millions	Mar. 31, 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