The Travelers Companies, Inc. (TRV) 10-Q17 Apr 242024 Q1 Quarterly reportFinancial data

Company Profile

Cover Page

Cover Page - shares	3 Months Ended
Cover Page - shares	Mar. 31, 2024	Apr. 11, 2024
Cover [Abstract]
Document type	10-Q
Document quarterly report	true
Document period end date	Mar. 31, 2024
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		228,993,392
Central index key	0000086312
Amendment flag	false
Current fiscal year end date	--12-31
Document fiscal year focus	2024
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, 2024	Mar. 31, 2023
Revenues
Premiums	$ 10,126	$ 8,854
Net investment income	846	663
Fee income	109	106
Net realized investment gains	35	6
Other revenues	112	75
Total revenues	11,228	9,704
Claims and expenses
Claims and claim adjustment expenses	6,656	5,959
Amortization of deferred acquisition costs	1,698	1,462
General and administrative expenses	1,406	1,267
Interest expense	98	88
Total claims and expenses	9,858	8,776
Income before income taxes	1,370	928
Income tax expense (benefit)	247	(47)
Net income	$ 1,123	$ 975
Net income per share
Basic (in dollars per share)	$ 4.87	$ 4.18
Diluted (in dollars per share)	$ 4.80	$ 4.13
Weighted average number of common shares outstanding
Basic (in shares)	229	231.7
Diluted (in shares)	232	234.4
Cash dividends declared per common share (in dollars per share)	$ 1	$ 0.93

Consolidated Statement of Compr

Consolidated Statement of Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Statement of Comprehensive Income [Abstract]
Net income	$ 1,123	$ 975
Other comprehensive income (loss):
Changes in net unrealized gains (losses) on investment securities having no credit losses recognized in the consolidated statement of income	(752)	1,308
Changes in net unrealized gains (losses) on investment securities having credit losses recognized in the consolidated statement of income	2	0
Net changes in benefit plan assets and obligations	(1)	(3)
Net changes in unrealized foreign currency translation	(71)	37
Other comprehensive income (loss) before income taxes	(822)	1,342
Income tax expense (benefit)	(162)	283
Other comprehensive income (loss), net of taxes	(660)	1,059
Comprehensive income	$ 463	$ 2,034

Consolidated Balance Sheet (Una

Consolidated Balance Sheet (Unaudited at March 31, 2024) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Assets
Fixed maturities, available for sale, at fair value (amortized cost $82,712 and $81,781; allowance for expected credit losses of $3 and $5)	$ 77,991	$ 77,807
Equity securities, at fair value (cost $557 and $553)	689	608
Real estate investments	958	959
Short-term securities	4,682	5,137
Other investments	4,337	4,299
Total investments	88,657	88,810
Cash	667	650
Investment income accrued	648	688
Premiums receivable (net of allowance for expected credit losses of $68 and $69)	10,829	10,282
Reinsurance recoverables (net of allowance for estimated uncollectible reinsurance of $117 and $118)	8,100	8,143
Ceded unearned premiums	1,535	1,150
Deferred acquisition costs	3,380	3,306
Deferred taxes	1,639	1,504
Contractholder receivables (net of allowance for expected credit losses of $19 and $20)	3,266	3,249
Goodwill	4,251	3,976
Other intangible assets	376	277
Other assets	4,062	3,943
Total assets	127,410	125,978
Liabilities
Claims and claim adjustment expense reserves	62,487	61,627
Unearned premium reserves	21,307	20,872
Contractholder payables	3,285	3,269
Payables for reinsurance premiums	887	518
Debt	8,032	8,031
Other liabilities	6,390	6,740
Total liabilities	102,388	101,057
Shareholders’ equity
Common stock (1,750.0 shares authorized; 229.0 and 228.2 shares issued and outstanding)	25,163	24,906
Retained earnings	46,483	45,591
Accumulated other comprehensive loss	(5,131)	(4,471)
Treasury stock, at cost (561.0 and 559.2 shares)	(41,493)	(41,105)
Total shareholders’ equity	25,022	24,921
Total liabilities and shareholders’ equity	$ 127,410	$ 125,978

Consolidated Balance Sheet Pare

Consolidated Balance Sheet Parentheticals (Unaudited at March 31, 2024) - USD ($) shares in Millions, $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Statement of Financial Position [Abstract]
Fixed maturities, available for sale, amortized cost	$ 82,712	$ 81,781
Fixed maturities, available for sale, allowance for expected credit losses	3	5
Equity securities, cost	557	553
Premiums receivable, allowance for expected credit losses	68	69
Reinsurance recoverables, allowance for estimated uncollectible reinsurance	117	118
Contractholder receivables, allowance for expected credit losses	$ 19	$ 20
Common stock, shares authorized (in shares)	1,750	1,750
Common stock, shares issued (in shares)	229	228.2
Common stock, shares outstanding (in shares)	229	228.2
Treasury stock, at cost (in shares)	561	559.2

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]	Accumulated other comprehensive loss, net of tax [Member]	Treasury stock, at cost [Member]	Common shares outstanding [Member]
Balance, beginning of period at Dec. 31, 2022		$ 24,565	$ 43,516	$ (6,445)	$ (40,076)
Shareholders' Equity [Roll Forward]
Employee share-based compensation		68
Compensation amortization under share-based plans and other changes		70
Net income	$ 975		975
Dividends			(218)
Other			0
Other comprehensive income (loss)	1,059			1,059
Treasury stock acquired — share repurchase authorizations					(400)
Net shares acquired related to employee share-based compensation plans					(62)
Balance, end of period at Mar. 31, 2023	23,052	24,703	44,273	(5,386)	(40,538)
Balance, beginning of period (in shares) at Dec. 31, 2022						232.1
Common shares outstanding
Treasury stock acquired — share repurchase authorizations (in shares)						(2.2)
Net shares issued under employee share-based compensation plans (in shares)						1.1
Balance, end of period (in shares) at Mar. 31, 2023						231
Balance, beginning of period at Dec. 31, 2023	24,921	24,906	45,591	(4,471)	(41,105)
Shareholders' Equity [Roll Forward]
Employee share-based compensation		179
Compensation amortization under share-based plans and other changes		78
Net income	1,123		1,123
Dividends			(232)
Other			1
Other comprehensive income (loss)	(660)			(660)
Treasury stock acquired — share repurchase authorizations	(250)				(250)
Net shares acquired related to employee share-based compensation plans	(138)				(138)
Balance, end of period at Mar. 31, 2024	$ 25,022	$ 25,163	$ 46,483	$ (5,131)	$ (41,493)
Balance, beginning of period (in shares) at Dec. 31, 2023	228.2					228.2
Common shares outstanding
Treasury stock acquired — share repurchase authorizations (in shares)	(1.2)					(1.2)
Net shares issued under employee share-based compensation plans (in shares)						2
Balance, end of period (in shares) at Mar. 31, 2024	229					229

Consolidated Statement of Cash

Consolidated Statement of Cash Flows (Unaudited) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Cash flows from operating activities
Net income	$ 1,123	$ 975
Adjustments to reconcile net income to net cash provided by operating activities:
Net realized investment gains	(35)	(6)
Depreciation and amortization	196	204
Deferred federal income tax expense	42	32
Amortization of deferred acquisition costs	1,698	1,462
Equity in income from other investments	(68)	(30)
Premiums receivable	(557)	(557)
Reinsurance recoverables	33	(24)
Deferred acquisition costs	(1,776)	(1,629)
Claims and claim adjustment expense reserves	928	381
Unearned premium reserves	457	893
Other operating activities	(583)	(689)
Net cash provided by operating activities	1,458	1,012
Cash flows from investing activities
Proceeds from maturities of fixed maturities	1,709	1,538
Proceeds from sales of investments:
Fixed maturities	942	2,364
Equity securities	21	28
Other investments	55	64
Purchases of investments:
Fixed maturities	(3,738)	(4,335)
Equity securities	(26)	(34)
Real estate investments	(13)	(14)
Other investments	(90)	(139)
Net sales of short-term securities	454	228
Securities transactions in the course of settlement	111	(35)
Acquisition, net of cash acquired	(381)	0
Other investing activities	(81)	(120)
Net cash used in investing activities	(1,037)	(455)
Cash flows from financing activities
Treasury stock acquired — share repurchase authorizations	(250)	(398)
Treasury stock acquired — net employee share-based compensation	(110)	(62)
Dividends paid to shareholders	(229)	(215)
Issuance of common stock — employee share options	190	82
Net cash used in financing activities	(399)	(593)
Effect of exchange rate changes on cash	(5)	4
Net increase (decrease) in cash	17	(32)
Cash at beginning of year	650	799
Cash at end of period	667	767
Supplemental disclosure of cash flow information
Income taxes paid (received)	24	(16)
Interest paid	60	60
Supplemental disclosure of noncash financing activities
Issuance of common stock — net share settlement of employee options	$ 28	$ 0

Basis of Presentation and Accou

Basis of Presentation and Accounting Policies	3 Months Ended
Basis of Presentation and Accounting Policies	Mar. 31, 2024
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, 2023 (the Company’s 2023 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. To the extent that the Company changes its accounting for, or presentation of, items in the financial statements, the presentation of such amounts in prior periods is changed to conform to the current period presentation, if appropriate, and disclosed, if material. On January 2, 2024, the Company completed its previously announced acquisition of all issued and outstanding shares of Corvus Insurance Holdings, Inc. (Corvus), a cyber insurance managing general underwriter, for consideration transferred of approximately $427 million. The acquisition provides the Company the opportunity to renew Corvus’s book of business and to leverage Corvus’s capabilities to enhance the return profile of Travelers’ existing cyber portfolio. At the acquisition date, the Company recorded at fair value $478 million of assets acquired and $51 million of liabilities assumed as part of purchase accounting, including $390 million of identifiable intangible assets and goodwill. The assets acquired from Corvus were included in the Company’s Bond & Specialty Insurance segment, effective at the acquisition date. The Company funded this transaction from internal resources. A provisional amount of $19 million has been recorded as a deferred tax asset and included on the consolidated balance sheet. As the tax return for Corvus for the 2023 fiscal year will not be finalized until the third quarter of 2024, a measurement period adjustment is expected to be recorded in the third quarter of 2024. Income Taxes The Company recognized a one-time tax benefit of $211 million in the first quarter of 2023 due to the expiration of the statute of limitations with respect to a tax item impacted by the repeal of Internal Revenue Code Section 847, which related to the discounting of property-casualty loss reserves.

Segment Information

Segment Information	3 Months Ended
Segment Information	Mar. 31, 2024
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 the notes to the consolidated financial statements in the Company’s 2023 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 Bond & Specialty Personal Total 2024 Premiums $ 5,160 $ 956 $ 4,010 $ 10,126 Net investment income 609 90 147 846 Fee income 101 — 8 109 Other revenues 77 9 26 112 Total segment revenues (1) $ 5,947 $ 1,055 $ 4,191 $ 11,193 Segment income (1) $ 764 $ 195 $ 220 $ 1,179 2023 Premiums $ 4,477 $ 875 $ 3,502 $ 8,854 Net investment income 473 73 117 663 Fee income 99 — 7 106 Other revenues 47 5 23 75 Total segment revenues (1) $ 5,096 $ 953 $ 3,649 $ 9,698 Segment income (1) $ 756 $ 207 $ 83 $ 1,046 ________________________________________________________ (1) Segment revenues for reportable business segments exclude net realized investment gains (losses) and revenues included in “interest expense and other.” Segment income for reportable business segments excludes the after-tax impact of net realized investment gains (losses) and income (loss) from “interest expense and other.” Business Segment Reconciliations Three Months Ended (in millions) 2024 2023 Revenue reconciliation Earned premiums Business Insurance: Domestic: Workers’ compensation $ 880 $ 850 Commercial automobile 860 761 Commercial property 873 709 General liability 847 760 Commercial multi-peril 1,270 1,100 Other 17 18 Total Domestic 4,747 4,198 International 413 279 Total Business Insurance 5,160 4,477 Bond & Specialty Insurance: Domestic: Fidelity and surety 340 306 General liability 426 398 Other 56 54 Total Domestic 822 758 International 134 117 Total Bond & Specialty Insurance 956 875 Personal Insurance: Domestic: Automobile 1,874 1,624 Homeowners and Other 1,972 1,724 Total Domestic 3,846 3,348 International 164 154 Total Personal Insurance 4,010 3,502 Total earned premiums 10,126 8,854 Net investment income 846 663 Fee income 109 106 Other revenues 112 75 Total segment revenues 11,193 9,698 Net realized investment gains 35 6 Total revenues $ 11,228 $ 9,704 Income reconciliation, net of tax Total segment income $ 1,179 $ 1,046 Interest Expense and Other (1) (83) (76) Core income 1,096 970 Net realized investment gains 27 5 Net income $ 1,123 $ 975 _________________________________________________________ (1) The primary component of Interest Expense and Other was after-tax interest expense of $77 million and $70 million for the three months ended March 31, 2024 and 2023, respectively. (in millions) March 31, December 31, Asset reconciliation Business Insurance $ 94,393 $ 93,565 Bond & Specialty Insurance 12,136 11,478 Personal Insurance 20,003 20,072 Total assets by reportable segment 126,532 125,115 Other assets (1) 878 863 Total consolidated assets $ 127,410 $ 125,978 _________________________________________________________ (1) The primary components of other assets at both March 31, 2024 and December 31, 2023 were the over-funded benefit plan assets related to the Company’s qualified domestic pension plan and other intangible assets.

Investments

Investments	3 Months Ended
Investments	Mar. 31, 2024
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, 2024, in millions) Gains Losses U.S. Treasury securities and obligations of U.S. government and government agencies and authorities $ 6,489 $ — $ 1 $ 250 $ 6,240 Obligations of U.S. states, municipalities and political subdivisions: Local general obligation 18,138 — 41 1,455 16,724 Revenue 9,419 — 27 700 8,746 State general obligation 1,156 — 3 67 1,092 Pre-refunded 952 — 2 4 950 Total obligations of U.S. states, municipalities and political subdivisions 29,665 — 73 2,226 27,512 Debt securities issued by foreign governments 970 — 1 32 939 Mortgage-backed securities, collateralized mortgage obligations and pass-through securities 9,076 — 68 224 8,920 Corporate and all other bonds 36,512 3 103 2,232 34,380 Total $ 82,712 $ 3 $ 246 $ 4,964 $ 77,991 Amortized Cost Allowance for Expected Credit Losses Gross Unrealized Fair Value (at December 31, 2023, in millions) Gains Losses U.S. Treasury securities and obligations of U.S. government and government agencies and authorities $ 6,591 $ — $ 8 $ 231 $ 6,368 Obligations of U.S. states, municipalities and political subdivisions: Local general obligation 18,374 — 90 1,265 17,199 Revenue 9,748 — 52 616 9,184 State general obligation 1,209 — 7 59 1,157 Pre-refunded 963 — 5 2 966 Total obligations of U.S. states, municipalities and political subdivisions 30,294 — 154 1,942 28,506 Debt securities issued by foreign governments 1,035 — 2 31 1,006 Mortgage-backed securities, collateralized mortgage obligations and pass-through securities 7,874 — 120 176 7,818 Corporate and all other bonds 35,987 5 187 2,060 34,109 Total $ 81,781 $ 5 $ 471 $ 4,440 $ 77,807 Pre-refunded bonds of $950 million and $966 million at March 31, 2024 and December 31, 2023, respectively, were bonds for which U.S. states or municipalities have established irrevocable trusts that are 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 the sales of fixed maturities classified as available for sale were $942 million and $2.36 billion during the three months ended March 31, 2024 and 2023, respectively. Gross gains of $2 million and $17 million and gross losses of $39 million and $27 million were realized on those sales during the three months ended March 31, 2024 and 2023, respectively. Equity Securities The cost and fair value of investments in equity securities were as follows: (at March 31, 2024, in millions) Cost Gross Gains Gross Losses Fair Value Common stock $ 512 $ 142 $ 13 $ 641 Non-redeemable preferred stock 45 3 — 48 Total $ 557 $ 145 $ 13 $ 689 (at December 31, 2023, in millions) Cost Gross Gains Gross Losses Fair Value Common stock $ 508 $ 93 $ 41 $ 560 Non-redeemable preferred stock 45 3 — 48 Total $ 553 $ 96 $ 41 $ 608 For the three months ended March 31, 2024 and 2023, the Company recognized $79 million and $17 million of net gains on equity securities still held as of March 31, 2024 and 2023, respectively. Unrealized Investment Losses The following tables summarize, for all fixed maturities classified as available for sale in an unrealized loss position at March 31, 2024 and December 31, 2023, the aggregate fair value and gross unrealized loss by the 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 the notes to the consolidated financial statements in the Company’s 2023 Annual Report. The Company also relies upon estimates of several factors in its review and evaluation of individual investments, using the process described in note 1 of the notes to the consolidated financial statements in the Company’s 2023 Annual Report to determine whether a credit loss impairment exists. Less than 12 months 12 months or longer Total (at March 31, 2024, in millions) Fair Gross Fair Gross Fair Gross Fixed maturities U.S. Treasury securities and obligations of U.S. government and government agencies and authorities $ 2,866 $ 17 $ 2,869 $ 233 $ 5,735 $ 250 Obligations of U.S. states, municipalities and political subdivisions 6,958 67 15,198 2,159 22,156 2,226 Debt securities issued by foreign governments 134 1 696 31 830 32 Mortgage-backed securities, collateralized mortgage obligations and pass-through securities 3,106 29 1,689 195 4,795 224 Corporate and all other bonds 2,957 28 25,668 2,204 28,625 2,232 Total $ 16,021 $ 142 $ 46,120 $ 4,822 $ 62,141 $ 4,964 Less than 12 months 12 months or longer Total (at December 31, 2023, in millions) Fair Gross Fair Gross Fair Gross Fixed maturities U.S. Treasury securities and obligations of U.S. government and government agencies and authorities $ 1,864 $ 7 $ 2,985 $ 224 $ 4,849 $ 231 Obligations of U.S. states, municipalities and political subdivisions 3,868 31 14,351 1,911 18,219 1,942 Debt securities issued by foreign governments 30 — 763 31 793 31 Mortgage-backed securities, collateralized mortgage obligations and pass-through securities 1,215 9 1,433 167 2,648 176 Corporate and all other bonds 1,016 9 26,444 2,051 27,460 2,060 Total $ 7,993 $ 56 $ 45,976 $ 4,384 $ 53,969 $ 4,440 The following tables summarize, for all fixed maturities reported at fair value for which fair value was less than 80% of amortized cost at March 31, 2024 and December 31, 2023, the gross unrealized investment loss by length of time those securities have continuously been in an unrealized loss position of greater than 20% of amortized cost: Period For Which Fair Value is Less Than 80% of Amortized Cost (at March 31, 2024, in millions) 3 months or less Greater than 3 months, 6 months or less Greater than 6 months, 12 months or less Greater than 12 months Total Fixed maturities U.S. Treasury securities and obligations of U.S. government and government agencies and authorities $ — $ — $ — $ — $ — Obligations of U.S. states, municipalities and political subdivisions 224 — 8 708 940 Debt securities issued by foreign governments — — — — — Mortgage-backed securities, collateralized mortgage obligations and pass-through securities 44 — — — 44 Corporate and all other bonds 41 2 1 23 67 Total $ 309 $ 2 $ 9 $ 731 $ 1,051 Period For Which Fair Value is Less Than 80% of Amortized Cost (at December 31, 2023, in millions) 3 months or less Greater than 3 months, 6 months or less Greater than 6 months, 12 months or less Greater than 12 months Total Fixed maturities U.S. Treasury securities and obligations of U.S. government and government agencies and authorities $ — $ — $ — $ — $ — Obligations of U.S. states, municipalities and political subdivisions — 2 31 642 675 Debt securities issued by foreign governments — — — — — Mortgage-backed securities, collateralized mortgage obligations and pass-through securities — — — — — Corporate and all other bonds 1 3 22 25 51 Total $ 1 $ 5 $ 53 $ 667 $ 726 Increases in interest rates resulted in the gross unrealized investment losses disclosed in the tables above; however, the net unrealized loss is considered temporary in nature as the decrease in value is not due to credit impairments and there is no impact on expected contractual cash flows from fixed maturities. Impairment Charges The following table presents changes in the allowance for expected credit losses on fixed maturities classified as available for sale for the category of Corporate and All Other Bonds (no other categories of fixed maturities currently have an allowance for expected credit losses): Fixed Maturities Corporate and All Other Bonds At and For the Three Months Ended (in millions) March 31, 2024 March 31, 2023 Balance, beginning of period $ 5 $ 3 Additions for expected credit losses on securities where no credit losses were previously recognized 3 — Additions for expected credit losses on securities where credit losses were previously recognized — 1 Reductions due to sales/defaults of credit-impaired securities (5) — Reductions for impairments of securities which the Company intends to sell or more likely than not will be required to sell — — Balance, end of period $ 3 $ 4 Total net impairment charges, including credit impairments, reported in net realized investment gains in the consolidated statement of income, were $3 million and $1 million for the three months ended March 31, 2024 and 2023, respectively. Credit losses related to the fixed maturity portfolio for both the three months ended March 31, 2024 and 2023 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. Other Investments Included in other investments are private equity, hedge fund 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 following the end of the reporting period. Accordingly, net investment income from these other investments is generally reflected in the Company’s financial statements on a quarter lag basis.

Fair Value Measurements

Fair Value Measurements	3 Months Ended
Fair Value Measurements	Mar. 31, 2024
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, 2024 and December 31, 2023. While the vast majority of the Company’s fixed maturities are included in Level 2, the Company holds a number of corporate bonds which are not valued by the pricing service and estimates the fair value of these bonds using either another internal pricing matrix, a present value income approach, or a broker quote (collectively, the other methodologies). The other methodologies include some unobservable inputs that are significant to the valuation. Due to the limited amount of observable market information available in the estimation of fair value, the Company includes the fair value estimates for bonds that are valued using the other methodologies in Level 3. For certain investments in non-public common and preferred equity securities, the fair value estimate is determined either internally or by an external fund manager based on the impact of recent observable transactions on the investment, recent filings, operating results, balance sheet stability, growth and other business and market sector fundamentals. Due to the significant unobservable inputs in these valuations, the Company included the fair value estimate of $37 million for these investments at both March 31, 2024 and December 31, 2023 in the amounts disclosed in Level 3. For more information regarding the valuation of the Company’s fixed maturities, equity securities and other investments, see note 4 of the notes to the consolidated financial statements in the Company’s 2023 Annual Report. 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, 2024, 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 $ 6,240 $ 6,240 $ — $ — Obligations of U.S. states, municipalities and political subdivisions 27,512 — 27,512 — Debt securities issued by foreign governments 939 — 939 — Mortgage-backed securities, collateralized mortgage obligations and pass-through securities 8,920 — 8,899 21 Corporate and all other bonds 34,380 — 34,125 255 Total fixed maturities 77,991 6,240 71,475 276 Equity securities Common stock 641 634 — 7 Non-redeemable preferred stock 48 15 3 30 Total equity securities 689 649 3 37 Other investments 18 18 — — Total $ 78,698 $ 6,907 $ 71,478 $ 313 (at December 31, 2023, 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 $ 6,368 $ 6,368 $ — $ — Obligations of U.S. states, municipalities and political subdivisions 28,506 — 28,506 — Debt securities issued by foreign governments 1,006 — 1,006 — Mortgage-backed securities, collateralized mortgage obligations and pass-through securities 7,818 — 7,818 — Corporate and all other bonds 34,109 — 33,851 258 Total fixed maturities 77,807 6,368 71,181 258 Equity securities Common stock 560 553 — 7 Non-redeemable preferred stock 48 16 2 30 Total equity securities 608 569 2 37 Other investments 18 18 — — Total $ 78,433 $ 6,955 $ 71,183 $ 295 There was no significant activity in Level 3 of the hierarchy during the three months ended March 31, 2024. 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, 2024, in millions) Carrying Fair Level 1 Level 2 Level 3 Financial assets Short-term securities $ 4,682 $ 4,682 $ 999 $ 3,634 $ 49 Financial liabilities Debt $ 7,932 $ 7,406 $ — $ 7,406 $ — Commercial paper 100 100 — 100 — (at December 31, 2023, in millions) Carrying Fair Level 1 Level 2 Level 3 Financial assets Short-term securities $ 5,137 $ 5,137 $ 1,171 $ 3,912 $ 54 Financial liabilities Debt $ 7,931 $ 7,645 $ — $ 7,645 $ — 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, 2024 or the year ended December 31, 2023.

Allowance for Expected Credit L

Allowance for Expected Credit Losses	3 Months Ended
Allowance for Expected Credit Losses	Mar. 31, 2024
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, 2024 and 2023, and the changes in the allowance for expected credit losses for the three months ended March 31, 2024 and 2023. At and For the Three Months Ended March 31, 2024 At and For the Three Months Ended March 31, 2023 (in millions) Premiums Receivable, Net of Allowance for Expected Credit Losses Allowance for Expected Credit Losses Premiums Receivable, Net of Allowance for Expected Credit Losses Allowance for Expected Credit Losses Balance, beginning of period $ 10,282 $ 69 $ 8,922 $ 77 Current period change for expected credit losses 12 10 Write-offs of uncollectible premiums receivable 13 10 Balance, end of period $ 10,829 $ 68 $ 9,483 $ 77 Reinsurance Recoverables The following table presents the balances of reinsurance recoverables, net of the allowance for estimated uncollectible reinsurance, at March 31, 2024 and 2023, and the changes in the allowance for estimated uncollectible reinsurance for the three months ended March 31, 2024 and 2023. At and For the Three Months Ended March 31, 2024 At and For the Three Months Ended March 31, 2023 (in millions) Reinsurance Recoverables, Net of Allowance for Estimated Uncollectible Reinsurance Allowance for Estimated Uncollectible Reinsurance Reinsurance Recoverables, Net of Allowance for Estimated Uncollectible Reinsurance Allowance for Estimated Uncollectible Reinsurance Balance, beginning of period $ 8,143 $ 118 $ 8,063 $ 132 Current period change for estimated uncollectible reinsurance (1) (1) Write-offs of uncollectible reinsurance recoverables — — Balance, end of period $ 8,100 $ 117 $ 8,091 $ 131 Of the total reinsurance recoverables at March 31, 2024, $5.70 billion, or 87%, were rated by A.M. Best Company, after deducting mandatory pools and associations and before allowances for estimated uncollectible reinsurance. 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, 94% were rated A- or better. The remaining 13% of reinsurance recoverables comprised 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, 2024 and 2023, and the changes in the allowance for expected credit losses for the three months ended March 31, 2024 and 2023. At and For the Three Months Ended March 31, 2024 At and For the Three Months Ended March 31, 2023 (in millions) Contractholder Receivables, Net of Allowance for Expected Credit Losses Allowance for Expected Credit Losses Contractholder Receivables, Net of Allowance for Expected Credit Losses Allowance for Expected Credit Losses Balance, beginning of period $ 3,249 $ 20 $ 3,579 $ 17 Current period change for expected credit losses (1) 2 Write-offs of uncollectible contractholder receivables — — Balance, end of period $ 3,266 $ 19 $ 3,598 $ 19

Goodwill and Other Intangible A

Goodwill and Other Intangible Assets	3 Months Ended
Goodwill and Other Intangible Assets	Mar. 31, 2024
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 $ 2,579 $ 2,585 Bond & Specialty Insurance (1) 835 550 Personal Insurance 811 815 Other 26 26 Total $ 4,251 $ 3,976 _________________________________________________________ (1) Goodwill at March 31, 2024 included $285 million associated with the acquisition of Corvus in the first quarter of 2024, which is primarily attributable to Corvus’s cyber underwriting and support capabilities and workforce, and it is not deductible for tax purposes. Other Intangible Assets The following tables present a summary of the Company’s other intangible assets by major asset class. (at March 31, 2024, in millions) Gross Accumulated Net Subject to amortization Customer-related (1) $ 186 $ 63 $ 123 Contract-based (2) 204 194 10 Marketing-related (3) 18 1 17 Total subject to amortization 408 258 150 Not subject to amortization 226 — 226 Total $ 634 $ 258 $ 376 (at December 31, 2023, in millions) Gross Accumulated Net Subject to amortization Customer-related $ 100 $ 59 $ 41 Contract-based (2) 204 194 10 Total subject to amortization 304 253 51 Not subject to amortization 226 — 226 Total $ 530 $ 253 $ 277 _________________________________________________________ (1) Customer-related intangibles of $87 million were recorded in connection with the acquisition of Corvus in the first quarter of 2024. The customer-related intangible assets include Corvus’s broker and policyholder relationships and were valued using the excess earnings method income approach, a valuation technique that provides an estimate of fair value based on the cash flows that the asset can be expected to generate over its remaining useful life. Broker relationships represent the relationships Corvus has with its existing brokers through which new business is placed with policyholders. Policyholder relationships represent the renewal of existing policies. Significant inputs to the fair valuation include estimates of revenue growth, broker retention rates, policyholder attrition rates and weighted average cost of capital. (2) 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. (3) Marketing-related intangibles of $18 million were recorded in connection with the acquisition of Corvus in the first quarter of 2024. The marketing-related intangible assets include trade names and a non-compete agreement. The trade names were valued using a relief from royalty method, a valuation technique which estimates the fair value of an asset based on the present value of the royalties saved because the company owns the asset. Significant inputs to the fair valuation include estimates of future revenue, appropriate rates of return associated with certain assets and weighted average cost of capital. The fair value of the non-compete agreement is based on an estimate of the income that would be lost if the agreement were not in place and the individual chose to compete. Significant inputs to the fair valuation include estimates of projected cash flows and weighted average cost of capital. The following table presents a summary of the other intangible assets recorded in connection with the acquisition of Corvus by major asset class as of the acquisition date. (in millions) Amount Weighted Average Amortization Period Subject to amortization Customer-related $ 87 14 years Marketing-related 18 7 years Total $ 105 13 years

Insurance Claim Reserves

Insurance Claim Reserves	3 Months Ended
Insurance Claim Reserves	Mar. 31, 2024
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 $ 62,482 $ 61,621 Accident and health 5 6 Total $ 62,487 $ 61,627 The following table presents a reconciliation of beginning and ending property casualty reserve balances for claims and claim adjustment expenses: Three Months Ended March 31, (in millions) 2024 2023 Claims and claim adjustment expense reserves at beginning of year $ 61,621 $ 58,643 Less reinsurance recoverables on unpaid losses 7,817 7,790 Net reserves at beginning of year 53,804 50,853 Estimated claims and claim adjustment expenses for claims arising in the current year 6,679 6,025 Estimated decrease in claims and claim adjustment expenses for claims arising in prior years (49) (90) Total increases 6,630 5,935 Claims and claim adjustment expense payments for claims arising in: Current year 1,275 1,177 Prior years 4,435 4,382 Total payments 5,710 5,559 Unrealized foreign exchange (gain) loss (61) 28 Net reserves at end of period 54,663 51,257 Plus reinsurance recoverables on unpaid losses 7,819 7,801 Claims and claim adjustment expense reserves at end of period $ 62,482 $ 59,058 Gross claims and claim adjustment expense reserves at March 31, 2024 increased by $861 million from December 31, 2023, primarily reflecting the impacts of (i) catastrophe losses in the first three months of 2024, (ii) higher volumes of insured exposures and (iii) loss cost trends for the current accident year, partially offset by (iv) claim payments made during the first three months of 2024 and (v) net favorable prior year reserve development. Reinsurance recoverables on unpaid losses at March 31, 2024 increased by $2 million from December 31, 2023. Prior Year Reserve Development The following disclosures regarding reserve development are on a “net of reinsurance” basis. For the three months ended March 31, 2024 and 2023, estimated claims and claim adjustment expenses incurred included $49 million and $90 million, respectively, of net favorable development for claims arising in prior years, including $91 million and $105 million, respectively, of net favorable prior year reserve development, and $11 million of accretion of discount in each period. Business Insurance. There was no net prior year reserve development in the first quarter of 2024, as better than expected loss experience in the domestic operations’ workers’ compensation product line for multiple accident years was offset primarily by higher than expected loss experience in the general liability product line for recent accident years, as well as an addition to reserves related to run-off operations. Net favorable prior year reserve development in the first quarter of 2023 totaled $19 million, primarily driven by better than expected loss experience in the domestic operations’ workers’ compensation product line for multiple accident years, partially offset by higher than expected loss experience in the general liability product line for excess coverages for multiple accident years. Bond & Specialty Insurance. Net favorable prior year reserve development in the first quarter of 2024 totaled $24 million, primarily driven by better than expected loss experience in multiple product lines within domestic operations. Net favorable prior year reserve development in the first quarter of 2023 totaled $58 million, primarily driven by better than expected loss experience in the domestic operations’ fidelity and surety product lines and in the general liability product line for management liability coverages for recent accident years. Personal Insurance. Net favorable prior year reserve development in the first quarter of 2024 totaled $67 million, primarily driven by better than expected loss experience in the domestic operations’ automobile product line for recent accident years. Net favorable prior year reserve development in the first quarter of 2023 totaled $28 million, primarily driven by better than expected loss experience in the domestic operations’ homeowners and other product line for recent accident years.

Other Comprehensive Income (Los

Other Comprehensive Income (Loss) and Accumulated Other Comprehensive Income (Loss)	3 Months Ended
	Mar. 31, 2024
Other Comprehensive Income And Accumulated Other Comprehensive Income Disclosure [Abstract]
Other Comprehensive Income (Loss) and Accumulated Other Comprehensive Income (Loss)	OTHER COMPREHENSIVE INCOME (LOSS) AND ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) The following table presents the changes in the Company’s accumulated other comprehensive income (loss) (AOCI) for the three months ended March 31, 2024. Changes in Net Unrealized Gains (Losses) on Investment Securities (in millions) Having No Credit Having Credit Net Benefit Plan Assets and Net Unrealized Total Accumulated Balance, December 31, 2023 $ (3,309) $ 180 $ (458) $ (884) $ (4,471) Other comprehensive income (loss) (OCI) before reclassifications, net of tax (626) 2 — (67) (691) Amounts reclassified from AOCI, net of tax 32 — (1) — 31 Net OCI, current period (594) 2 (1) (67) (660) Balance, March 31, 2024 $ (3,903) $ 182 $ (459) $ (951) $ (5,131) 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) 2024 2023 Changes in net unrealized losses on investment securities: Having no credit losses recognized in the consolidated statement of income $ (752) $ 1,308 Income tax expense (benefit) (158) 278 Net of taxes (594) 1,030 Having credit losses recognized in the consolidated statement of income 2 — Income tax expense — — Net of taxes 2 — Net changes in benefit plan assets and obligations (1) (3) Income tax expense (benefit) — (1) Net of taxes (1) (2) Net changes in unrealized foreign currency translation (71) 37 Income tax expense (benefit) (4) 6 Net of taxes (67) 31 Total other comprehensive income (loss) (822) 1,342 Total income tax expense (benefit) (162) 283 Total other comprehensive income (loss), net of taxes $ (660) $ 1,059 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) 2024 2023 Reclassification adjustments related to unrealized gains (losses) on investment securities: Having no credit losses recognized in the consolidated statement of income (1) $ 40 $ 11 Income tax benefit (2) 8 2 Net of taxes 32 9 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 (benefit) (3) — (1) General and administrative expenses (benefit) (3) (1) (2) Total (1) (3) Income tax (expense) benefit (2) — — Net of taxes (1) (3) Reclassification adjustment related to foreign currency translation (1) — — Income tax benefit (2) — — Net of taxes — — Total reclassifications 39 8 Total income tax benefit 8 2 Total reclassifications, net of taxes $ 31 $ 6 _________________________________________________________ (1) (Increases) decreases net realized investment gains on the consolidated statement of income. (2) (Increases) decreases income tax expense (benefit) 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
Common Share Repurchases	Mar. 31, 2024
Treasury Stock Transactions, Excluding Value of Shares Reissued [Abstract]
Common Share Repurchases	COMMON SHARE REPURCHASES During the three months ended March 31, 2024, the Company repurchased 1.2 million common shares under its share repurchase authorizations for a total cost of $250 million. The average cost per share repurchased was $217.31. In addition, the Company acquired 0.6 million common shares for a total cost of $138 million during the three months ended March 31, 2024 that were not part of its publicly announced share repurchase authorizations. 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 exercise price, as well as the related payroll withholding taxes, with respect to certain stock options that were exercised. Included in the cost of treasury stock acquired pursuant to common share repurchases is the 1% excise tax imposed on common share repurchase activity, net of common share issuances, as part of the Inflation Reduction Act of 2022. During the three months ended March 31, 2024, there was no net excise tax included in the cost of treasury stock acquired, as common share issuances exceeded common share repurchase activity. At March 31, 2024, the Company had $5.79 billion of capacity remaining under its share repurchase authorizations.

Earnings per Share

Earnings per Share	3 Months Ended
Earnings per Share	Mar. 31, 2024
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) 2024 2023 Basic and Diluted Net income, as reported $ 1,123 $ 975 Participating share-based awards — allocated income (8) (7) Net income available to common shareholders — basic and diluted $ 1,115 $ 968 Common Shares Basic Weighted average shares outstanding 229.0 231.7 Diluted Weighted average shares outstanding 229.0 231.7 Weighted average effects of dilutive securities — stock options and performance shares 3.0 2.7 Total 232.0 234.4 Net Income per Common Share Basic $ 4.87 $ 4.18 Diluted $ 4.80 $ 4.13

Share-Based Incentive Compensat

Share-Based Incentive Compensation	3 Months Ended
Share-Based Incentive Compensation	Mar. 31, 2024
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, 2024: Stock Options Number Weighted Weighted Aggregate Vested at end of period (1) 6,832,710 $ 146.39 6.0 years $ 572 Exercisable at end of period 5,162,950 $ 132.57 5.1 years $ 504 _________________________________________________________ (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 $79 million and $69 million for the three months ended March 31, 2024 and 2023, respectively. The related tax benefits recognized in earnings were $12 million and $11 million for the three months ended March 31, 2024 and 2023, respectively. The total unrecognized compensation cost related to all nonvested share-based incentive compensation awards at March 31, 2024 was $380 million, which is expected to be recognized over a weighted-average period of 2.2 years.

Pension Plans, Retirement Benef

Pension Plans, Retirement Benefits and Savings Plans	3 Months Ended
Pension Plans, Retirement Benefits and Savings Plans	Mar. 31, 2024
Retirement Benefits [Abstract]
Pension Plans, Retirement Benefits and Savings Plans	PENSION PLANS, RETIREMENT BENEFITS AND SAVINGS PLANS The following table summarizes the components of net periodic benefit cost (benefit) for the Company’s pension and postretirement benefit plans recognized in the consolidated statement of income for the three months ended March 31, 2024 and 2023. Pension Plans Postretirement Benefit Plans (for the three months ended March 31, in millions) 2024 2023 2024 2023 Net Periodic Benefit Cost (Benefit): Service cost $ 29 $ 27 $ — $ — Non-service cost (benefit): Interest cost on benefit obligation 43 44 1 1 Expected return on plan assets (75) (78) — — Amortization of unrecognized: Prior service benefit — — (1) (1) Net actuarial (gain) loss 2 — (2) (2) Total non-service cost (benefit) (30) (34) (2) (2) Net periodic benefit cost (benefit) $ (1) $ (7) $ (2) $ (2) 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, 2024 and 2023. Pension Plans Postretirement Benefit Plans (for the three months ended March 31, in millions) 2024 2023 2024 2023 Service Cost: Claims and claim adjustment expenses $ 11 $ 11 $ — $ — General and administrative expenses 18 16 — — Total service cost 29 27 — — Non-Service Cost (Benefit): Claims and claim adjustment expenses (12) (14) (1) (1) General and administrative expenses (18) (20) (1) (1) Total non-service cost (benefit) (30) (34) (2) (2) Net periodic benefit cost (benefit) $ (1) $ (7) $ (2) $ (2)

Leases

Leases	3 Months Ended
Leases	Mar. 31, 2024
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) 2024 2023 Lease cost Operating leases $ 19 $ 19 Short-term leases (1) 1 1 Lease expense 20 20 Less: sublease income (2) — — Net lease cost $ 20 $ 20 Other information on operating leases Cash payments to settle a lease liability reported in cash flows $ 22 $ 21 Right-of-use assets obtained in exchange for new lease liabilities $ 10 $ 10 Weighted average discount rate 2.91 % 2.44 % Weighted average remaining lease term 4.1 years 4.4 years _________________________________________________________ (1) Leases with a term of twelve months or less are not recorded on the consolidated balance sheet. (2)

Contingencies, Commitments and

Contingencies, Commitments and Guarantees	3 Months Ended
Contingencies, Commitments and Guarantees	Mar. 31, 2024
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, real estate partnerships and other investments. These commitments totaled $1.59 billion and $2.05 billion at March 31, 2024 and December 31, 2023, 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, 2024. 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, 2024, all of which is indemnified by a third party. For more information regarding the Company’s guarantees, see note 17 of the notes to the consolidated financial statements in the Company’s 2023 Annual Report.

Pay vs Performance Disclosure

Pay vs Performance Disclosure - USD ($) $ in Millions	3 Months Ended
Pay vs Performance Disclosure - USD ($) $ in Millions	Mar. 31, 2024	Mar. 31, 2023
Pay vs Performance Disclosure
Net income	$ 1,123	$ 975

Insider Trading Arrangements

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

Basis of Presentation and Acc_2

Basis of Presentation and Accounting Policies (Policies)	3 Months Ended
Basis of Presentation and Accounting Policies (Policies)	Mar. 31, 2024
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, 2023 (the Company’s 2023 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. To the extent that the Company changes its accounting for, or presentation of, items in the financial statements, the presentation of such amounts in prior periods is changed to conform to the current period presentation, if appropriate, and disclosed, if material.
Acquisition [Policy Text Block]	On January 2, 2024, the Company completed its previously announced acquisition of all issued and outstanding shares of Corvus Insurance Holdings, Inc. (Corvus), a cyber insurance managing general underwriter, for consideration transferred of approximately $427 million. The acquisition provides the Company the opportunity to renew Corvus’s book of business and to leverage Corvus’s capabilities to enhance the return profile of Travelers’ existing cyber portfolio. At the acquisition date, the Company recorded at fair value $478 million of assets acquired and $51 million of liabilities assumed as part of purchase accounting, including $390 million of identifiable intangible assets and goodwill. The assets acquired from Corvus were included in the Company’s Bond & Specialty Insurance segment, effective at the acquisition date. The Company funded this transaction from internal resources. A provisional amount of $19 million has been recorded as a deferred tax asset and included on the consolidated balance sheet. As the tax return for Corvus for the 2023 fiscal year will not be finalized until the third quarter of 2024, a measurement period adjustment is expected to be recorded in the third quarter of 2024.

Segment Information (Tables)

Segment Information (Tables)	3 Months Ended
Segment Information (Tables)	Mar. 31, 2024
Segment Reporting [Abstract]
Company's revenues and income by segment [Table Text Block]	(For the three months ended March 31, in millions) Business Bond & Specialty Personal Total 2024 Premiums $ 5,160 $ 956 $ 4,010 $ 10,126 Net investment income 609 90 147 846 Fee income 101 — 8 109 Other revenues 77 9 26 112 Total segment revenues (1) $ 5,947 $ 1,055 $ 4,191 $ 11,193 Segment income (1) $ 764 $ 195 $ 220 $ 1,179 2023 Premiums $ 4,477 $ 875 $ 3,502 $ 8,854 Net investment income 473 73 117 663 Fee income 99 — 7 106 Other revenues 47 5 23 75 Total segment revenues (1) $ 5,096 $ 953 $ 3,649 $ 9,698 Segment income (1) $ 756 $ 207 $ 83 $ 1,046 ________________________________________________________ (1) Segment revenues for reportable business segments exclude net realized investment gains (losses) and revenues included in “interest expense and other.” Segment income for reportable business segments excludes the after-tax impact of net realized investment gains (losses) and income (loss) from “interest expense and other.”
Business segment reconciliations of revenue and income, net of tax [Table Text Block]	Business Segment Reconciliations Three Months Ended (in millions) 2024 2023 Revenue reconciliation Earned premiums Business Insurance: Domestic: Workers’ compensation $ 880 $ 850 Commercial automobile 860 761 Commercial property 873 709 General liability 847 760 Commercial multi-peril 1,270 1,100 Other 17 18 Total Domestic 4,747 4,198 International 413 279 Total Business Insurance 5,160 4,477 Bond & Specialty Insurance: Domestic: Fidelity and surety 340 306 General liability 426 398 Other 56 54 Total Domestic 822 758 International 134 117 Total Bond & Specialty Insurance 956 875 Personal Insurance: Domestic: Automobile 1,874 1,624 Homeowners and Other 1,972 1,724 Total Domestic 3,846 3,348 International 164 154 Total Personal Insurance 4,010 3,502 Total earned premiums 10,126 8,854 Net investment income 846 663 Fee income 109 106 Other revenues 112 75 Total segment revenues 11,193 9,698 Net realized investment gains 35 6 Total revenues $ 11,228 $ 9,704 Income reconciliation, net of tax Total segment income $ 1,179 $ 1,046 Interest Expense and Other (1) (83) (76) Core income 1,096 970 Net realized investment gains 27 5 Net income $ 1,123 $ 975 _________________________________________________________ (1) The primary component of Interest Expense and Other was after-tax interest expense of $77 million and $70 million for the three months ended March 31, 2024 and 2023, respectively.
Asset reconciliation [Table Text Block]	(in millions) March 31, December 31, Asset reconciliation Business Insurance $ 94,393 $ 93,565 Bond & Specialty Insurance 12,136 11,478 Personal Insurance 20,003 20,072 Total assets by reportable segment 126,532 125,115 Other assets (1) 878 863 Total consolidated assets $ 127,410 $ 125,978 _________________________________________________________ (1) The primary components of other assets at both March 31, 2024 and December 31, 2023 were the 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
Investments (Tables)	Mar. 31, 2024
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, 2024, in millions) Gains Losses U.S. Treasury securities and obligations of U.S. government and government agencies and authorities $ 6,489 $ — $ 1 $ 250 $ 6,240 Obligations of U.S. states, municipalities and political subdivisions: Local general obligation 18,138 — 41 1,455 16,724 Revenue 9,419 — 27 700 8,746 State general obligation 1,156 — 3 67 1,092 Pre-refunded 952 — 2 4 950 Total obligations of U.S. states, municipalities and political subdivisions 29,665 — 73 2,226 27,512 Debt securities issued by foreign governments 970 — 1 32 939 Mortgage-backed securities, collateralized mortgage obligations and pass-through securities 9,076 — 68 224 8,920 Corporate and all other bonds 36,512 3 103 2,232 34,380 Total $ 82,712 $ 3 $ 246 $ 4,964 $ 77,991 Amortized Cost Allowance for Expected Credit Losses Gross Unrealized Fair Value (at December 31, 2023, in millions) Gains Losses U.S. Treasury securities and obligations of U.S. government and government agencies and authorities $ 6,591 $ — $ 8 $ 231 $ 6,368 Obligations of U.S. states, municipalities and political subdivisions: Local general obligation 18,374 — 90 1,265 17,199 Revenue 9,748 — 52 616 9,184 State general obligation 1,209 — 7 59 1,157 Pre-refunded 963 — 5 2 966 Total obligations of U.S. states, municipalities and political subdivisions 30,294 — 154 1,942 28,506 Debt securities issued by foreign governments 1,035 — 2 31 1,006 Mortgage-backed securities, collateralized mortgage obligations and pass-through securities 7,874 — 120 176 7,818 Corporate and all other bonds 35,987 5 187 2,060 34,109 Total $ 81,781 $ 5 $ 471 $ 4,440 $ 77,807
Cost and fair value of investments in equity securities [Table Text Block]	The cost and fair value of investments in equity securities were as follows: (at March 31, 2024, in millions) Cost Gross Gains Gross Losses Fair Value Common stock $ 512 $ 142 $ 13 $ 641 Non-redeemable preferred stock 45 3 — 48 Total $ 557 $ 145 $ 13 $ 689 (at December 31, 2023, in millions) Cost Gross Gains Gross Losses Fair Value Common stock $ 508 $ 93 $ 41 $ 560 Non-redeemable preferred stock 45 3 — 48 Total $ 553 $ 96 $ 41 $ 608
Unrealized investment losses [Table Text Block]	The following tables summarize, for all fixed maturities classified as available for sale in an unrealized loss position at March 31, 2024 and December 31, 2023, the aggregate fair value and gross unrealized loss by the 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 the notes to the consolidated financial statements in the Company’s 2023 Annual Report. The Company also relies upon estimates of several factors in its review and evaluation of individual investments, using the process described in note 1 of the notes to the consolidated financial statements in the Company’s 2023 Annual Report to determine whether a credit loss impairment exists. Less than 12 months 12 months or longer Total (at March 31, 2024, in millions) Fair Gross Fair Gross Fair Gross Fixed maturities U.S. Treasury securities and obligations of U.S. government and government agencies and authorities $ 2,866 $ 17 $ 2,869 $ 233 $ 5,735 $ 250 Obligations of U.S. states, municipalities and political subdivisions 6,958 67 15,198 2,159 22,156 2,226 Debt securities issued by foreign governments 134 1 696 31 830 32 Mortgage-backed securities, collateralized mortgage obligations and pass-through securities 3,106 29 1,689 195 4,795 224 Corporate and all other bonds 2,957 28 25,668 2,204 28,625 2,232 Total $ 16,021 $ 142 $ 46,120 $ 4,822 $ 62,141 $ 4,964 Less than 12 months 12 months or longer Total (at December 31, 2023, in millions) Fair Gross Fair Gross Fair Gross Fixed maturities U.S. Treasury securities and obligations of U.S. government and government agencies and authorities $ 1,864 $ 7 $ 2,985 $ 224 $ 4,849 $ 231 Obligations of U.S. states, municipalities and political subdivisions 3,868 31 14,351 1,911 18,219 1,942 Debt securities issued by foreign governments 30 — 763 31 793 31 Mortgage-backed securities, collateralized mortgage obligations and pass-through securities 1,215 9 1,433 167 2,648 176 Corporate and all other bonds 1,016 9 26,444 2,051 27,460 2,060 Total $ 7,993 $ 56 $ 45,976 $ 4,384 $ 53,969 $ 4,440
Gross unrealized investment losses on securities continuously in an unrealized loss position of greater than 20% of amortized cost by length of time [Table Text Block]	The following tables summarize, for all fixed maturities reported at fair value for which fair value was less than 80% of amortized cost at March 31, 2024 and December 31, 2023, the gross unrealized investment loss by length of time those securities have continuously been in an unrealized loss position of greater than 20% of amortized cost: Period For Which Fair Value is Less Than 80% of Amortized Cost (at March 31, 2024, in millions) 3 months or less Greater than 3 months, 6 months or less Greater than 6 months, 12 months or less Greater than 12 months Total Fixed maturities U.S. Treasury securities and obligations of U.S. government and government agencies and authorities $ — $ — $ — $ — $ — Obligations of U.S. states, municipalities and political subdivisions 224 — 8 708 940 Debt securities issued by foreign governments — — — — — Mortgage-backed securities, collateralized mortgage obligations and pass-through securities 44 — — — 44 Corporate and all other bonds 41 2 1 23 67 Total $ 309 $ 2 $ 9 $ 731 $ 1,051 Period For Which Fair Value is Less Than 80% of Amortized Cost (at December 31, 2023, in millions) 3 months or less Greater than 3 months, 6 months or less Greater than 6 months, 12 months or less Greater than 12 months Total Fixed maturities U.S. Treasury securities and obligations of U.S. government and government agencies and authorities $ — $ — $ — $ — $ — Obligations of U.S. states, municipalities and political subdivisions — 2 31 642 675 Debt securities issued by foreign governments — — — — — Mortgage-backed securities, collateralized mortgage obligations and pass-through securities — — — — — Corporate and all other bonds 1 3 22 25 51 Total $ 1 $ 5 $ 53 $ 667 $ 726
Changes in the allowance for expected credit losses on fixed maturities classified as available for sale [Table Text Block]	The following table presents changes in the allowance for expected credit losses on fixed maturities classified as available for sale for the category of Corporate and All Other Bonds (no other categories of fixed maturities currently have an allowance for expected credit losses): Fixed Maturities Corporate and All Other Bonds At and For the Three Months Ended (in millions) March 31, 2024 March 31, 2023 Balance, beginning of period $ 5 $ 3 Additions for expected credit losses on securities where no credit losses were previously recognized 3 — Additions for expected credit losses on securities where credit losses were previously recognized — 1 Reductions due to sales/defaults of credit-impaired securities (5) — Reductions for impairments of securities which the Company intends to sell or more likely than not will be required to sell — — Balance, end of period $ 3 $ 4

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
Fair Value Measurements (Tables)	Mar. 31, 2024
Fair Value Disclosures [Abstract]
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities 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, 2024, 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 $ 6,240 $ 6,240 $ — $ — Obligations of U.S. states, municipalities and political subdivisions 27,512 — 27,512 — Debt securities issued by foreign governments 939 — 939 — Mortgage-backed securities, collateralized mortgage obligations and pass-through securities 8,920 — 8,899 21 Corporate and all other bonds 34,380 — 34,125 255 Total fixed maturities 77,991 6,240 71,475 276 Equity securities Common stock 641 634 — 7 Non-redeemable preferred stock 48 15 3 30 Total equity securities 689 649 3 37 Other investments 18 18 — — Total $ 78,698 $ 6,907 $ 71,478 $ 313 (at December 31, 2023, 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 $ 6,368 $ 6,368 $ — $ — Obligations of U.S. states, municipalities and political subdivisions 28,506 — 28,506 — Debt securities issued by foreign governments 1,006 — 1,006 — Mortgage-backed securities, collateralized mortgage obligations and pass-through securities 7,818 — 7,818 — Corporate and all other bonds 34,109 — 33,851 258 Total fixed maturities 77,807 6,368 71,181 258 Equity securities Common stock 560 553 — 7 Non-redeemable preferred stock 48 16 2 30 Total equity securities 608 569 2 37 Other investments 18 18 — — Total $ 78,433 $ 6,955 $ 71,183 $ 295
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 [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, 2024, in millions) Carrying Fair Level 1 Level 2 Level 3 Financial assets Short-term securities $ 4,682 $ 4,682 $ 999 $ 3,634 $ 49 Financial liabilities Debt $ 7,932 $ 7,406 $ — $ 7,406 $ — Commercial paper 100 100 — 100 — (at December 31, 2023, in millions) Carrying Fair Level 1 Level 2 Level 3 Financial assets Short-term securities $ 5,137 $ 5,137 $ 1,171 $ 3,912 $ 54 Financial liabilities Debt $ 7,931 $ 7,645 $ — $ 7,645 $ — Commercial paper 100 100 — 100 —

Allowance for Expected Credit_2

Allowance for Expected Credit Losses (Tables)	3 Months Ended
Allowance for Expected Credit Losses (Tables)	Mar. 31, 2024
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, 2024 and 2023, and the changes in the allowance for expected credit losses for the three months ended March 31, 2024 and 2023. At and For the Three Months Ended March 31, 2024 At and For the Three Months Ended March 31, 2023 (in millions) Premiums Receivable, Net of Allowance for Expected Credit Losses Allowance for Expected Credit Losses Premiums Receivable, Net of Allowance for Expected Credit Losses Allowance for Expected Credit Losses Balance, beginning of period $ 10,282 $ 69 $ 8,922 $ 77 Current period change for expected credit losses 12 10 Write-offs of uncollectible premiums receivable 13 10 Balance, end of period $ 10,829 $ 68 $ 9,483 $ 77
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, 2024 and 2023, and the changes in the allowance for estimated uncollectible reinsurance for the three months ended March 31, 2024 and 2023. At and For the Three Months Ended March 31, 2024 At and For the Three Months Ended March 31, 2023 (in millions) Reinsurance Recoverables, Net of Allowance for Estimated Uncollectible Reinsurance Allowance for Estimated Uncollectible Reinsurance Reinsurance Recoverables, Net of Allowance for Estimated Uncollectible Reinsurance Allowance for Estimated Uncollectible Reinsurance Balance, beginning of period $ 8,143 $ 118 $ 8,063 $ 132 Current period change for estimated uncollectible reinsurance (1) (1) Write-offs of uncollectible reinsurance recoverables — — Balance, end of period $ 8,100 $ 117 $ 8,091 $ 131
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, 2024 and 2023, and the changes in the allowance for expected credit losses for the three months ended March 31, 2024 and 2023. At and For the Three Months Ended March 31, 2024 At and For the Three Months Ended March 31, 2023 (in millions) Contractholder Receivables, Net of Allowance for Expected Credit Losses Allowance for Expected Credit Losses Contractholder Receivables, Net of Allowance for Expected Credit Losses Allowance for Expected Credit Losses Balance, beginning of period $ 3,249 $ 20 $ 3,579 $ 17 Current period change for expected credit losses (1) 2 Write-offs of uncollectible contractholder receivables — — Balance, end of period $ 3,266 $ 19 $ 3,598 $ 19

Goodwill and Other Intangible_2

Goodwill and Other Intangible Assets (Tables)	3 Months Ended
Goodwill and Other Intangible Assets (Tables)	Mar. 31, 2024
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 $ 2,579 $ 2,585 Bond & Specialty Insurance (1) 835 550 Personal Insurance 811 815 Other 26 26 Total $ 4,251 $ 3,976 _________________________________________________________ (1) Goodwill at March 31, 2024 included $285 million associated with the acquisition of Corvus in the first quarter of 2024, which is primarily attributable to Corvus’s cyber underwriting and support capabilities and workforce, and it is not deductible for tax purposes.
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, 2024, in millions) Gross Accumulated Net Subject to amortization Customer-related (1) $ 186 $ 63 $ 123 Contract-based (2) 204 194 10 Marketing-related (3) 18 1 17 Total subject to amortization 408 258 150 Not subject to amortization 226 — 226 Total $ 634 $ 258 $ 376 (at December 31, 2023, in millions) Gross Accumulated Net Subject to amortization Customer-related $ 100 $ 59 $ 41 Contract-based (2) 204 194 10 Total subject to amortization 304 253 51 Not subject to amortization 226 — 226 Total $ 530 $ 253 $ 277 _________________________________________________________ (1) Customer-related intangibles of $87 million were recorded in connection with the acquisition of Corvus in the first quarter of 2024. The customer-related intangible assets include Corvus’s broker and policyholder relationships and were valued using the excess earnings method income approach, a valuation technique that provides an estimate of fair value based on the cash flows that the asset can be expected to generate over its remaining useful life. Broker relationships represent the relationships Corvus has with its existing brokers through which new business is placed with policyholders. Policyholder relationships represent the renewal of existing policies. Significant inputs to the fair valuation include estimates of revenue growth, broker retention rates, policyholder attrition rates and weighted average cost of capital. (2) 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. (3) Marketing-related intangibles of $18 million were recorded in connection with the acquisition of Corvus in the first quarter of 2024. The marketing-related intangible assets include trade names and a non-compete agreement. The trade names were valued using a relief from royalty method, a valuation technique which estimates the fair value of an asset based on the present value of the royalties saved because the company owns the asset. Significant inputs to the fair valuation include estimates of future revenue, appropriate rates of return associated with certain assets and weighted average cost of capital. The fair value of the non-compete agreement is based on an estimate of the income that would be lost if the agreement were not in place and the individual chose to compete. Significant inputs to the fair valuation include estimates of projected cash flows and weighted average cost of capital.
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, 2024, in millions) Gross Accumulated Net Subject to amortization Customer-related (1) $ 186 $ 63 $ 123 Contract-based (2) 204 194 10 Marketing-related (3) 18 1 17 Total subject to amortization 408 258 150 Not subject to amortization 226 — 226 Total $ 634 $ 258 $ 376 (at December 31, 2023, in millions) Gross Accumulated Net Subject to amortization Customer-related $ 100 $ 59 $ 41 Contract-based (2) 204 194 10 Total subject to amortization 304 253 51 Not subject to amortization 226 — 226 Total $ 530 $ 253 $ 277 _________________________________________________________ (1) Customer-related intangibles of $87 million were recorded in connection with the acquisition of Corvus in the first quarter of 2024. The customer-related intangible assets include Corvus’s broker and policyholder relationships and were valued using the excess earnings method income approach, a valuation technique that provides an estimate of fair value based on the cash flows that the asset can be expected to generate over its remaining useful life. Broker relationships represent the relationships Corvus has with its existing brokers through which new business is placed with policyholders. Policyholder relationships represent the renewal of existing policies. Significant inputs to the fair valuation include estimates of revenue growth, broker retention rates, policyholder attrition rates and weighted average cost of capital. (2) 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. (3) Marketing-related intangibles of $18 million were recorded in connection with the acquisition of Corvus in the first quarter of 2024. The marketing-related intangible assets include trade names and a non-compete agreement. The trade names were valued using a relief from royalty method, a valuation technique which estimates the fair value of an asset based on the present value of the royalties saved because the company owns the asset. Significant inputs to the fair valuation include estimates of future revenue, appropriate rates of return associated with certain assets and weighted average cost of capital. The fair value of the non-compete agreement is based on an estimate of the income that would be lost if the agreement were not in place and the individual chose to compete. Significant inputs to the fair valuation include estimates of projected cash flows and weighted average cost of capital.
Other intangible assets recorded in connection with Corvus acquisition by major asset class [Table Text Block]	The following table presents a summary of the other intangible assets recorded in connection with the acquisition of Corvus by major asset class as of the acquisition date. (in millions) Amount Weighted Average Amortization Period Subject to amortization Customer-related $ 87 14 years Marketing-related 18 7 years Total $ 105 13 years

Insurance Claim Reserves (Table

Insurance Claim Reserves (Tables)	3 Months Ended
Insurance Claim Reserves (Tables)	Mar. 31, 2024
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 $ 62,482 $ 61,621 Accident and health 5 6 Total $ 62,487 $ 61,627
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 March 31, (in millions) 2024 2023 Claims and claim adjustment expense reserves at beginning of year $ 61,621 $ 58,643 Less reinsurance recoverables on unpaid losses 7,817 7,790 Net reserves at beginning of year 53,804 50,853 Estimated claims and claim adjustment expenses for claims arising in the current year 6,679 6,025 Estimated decrease in claims and claim adjustment expenses for claims arising in prior years (49) (90) Total increases 6,630 5,935 Claims and claim adjustment expense payments for claims arising in: Current year 1,275 1,177 Prior years 4,435 4,382 Total payments 5,710 5,559 Unrealized foreign exchange (gain) loss (61) 28 Net reserves at end of period 54,663 51,257 Plus reinsurance recoverables on unpaid losses 7,819 7,801 Claims and claim adjustment expense reserves at end of period $ 62,482 $ 59,058

Other Comprehensive Income (L_2

Other Comprehensive Income (Loss) and Accumulated Other Comprehensive Income (Loss) (Tables)	3 Months Ended
	Mar. 31, 2024
Other Comprehensive Income And Accumulated Other Comprehensive Income Disclosure [Abstract]
Changes in accumulated other comprehensive income (loss) (AOCI) [Table Text Block]	The following table presents the changes in the Company’s accumulated other comprehensive income (loss) (AOCI) for the three months ended March 31, 2024. Changes in Net Unrealized Gains (Losses) on Investment Securities (in millions) Having No Credit Having Credit Net Benefit Plan Assets and Net Unrealized Total Accumulated Balance, December 31, 2023 $ (3,309) $ 180 $ (458) $ (884) $ (4,471) Other comprehensive income (loss) (OCI) before reclassifications, net of tax (626) 2 — (67) (691) Amounts reclassified from AOCI, net of tax 32 — (1) — 31 Net OCI, current period (594) 2 (1) (67) (660) Balance, March 31, 2024 $ (3,903) $ 182 $ (459) $ (951) $ (5,131)
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) 2024 2023 Changes in net unrealized losses on investment securities: Having no credit losses recognized in the consolidated statement of income $ (752) $ 1,308 Income tax expense (benefit) (158) 278 Net of taxes (594) 1,030 Having credit losses recognized in the consolidated statement of income 2 — Income tax expense — — Net of taxes 2 — Net changes in benefit plan assets and obligations (1) (3) Income tax expense (benefit) — (1) Net of taxes (1) (2) Net changes in unrealized foreign currency translation (71) 37 Income tax expense (benefit) (4) 6 Net of taxes (67) 31 Total other comprehensive income (loss) (822) 1,342 Total income tax expense (benefit) (162) 283 Total other comprehensive income (loss), net of taxes $ (660) $ 1,059
Pre-tax and related income tax (expense) benefit components of the amounts reclassified from AOCI 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) 2024 2023 Reclassification adjustments related to unrealized gains (losses) on investment securities: Having no credit losses recognized in the consolidated statement of income (1) $ 40 $ 11 Income tax benefit (2) 8 2 Net of taxes 32 9 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 (benefit) (3) — (1) General and administrative expenses (benefit) (3) (1) (2) Total (1) (3) Income tax (expense) benefit (2) — — Net of taxes (1) (3) Reclassification adjustment related to foreign currency translation (1) — — Income tax benefit (2) — — Net of taxes — — Total reclassifications 39 8 Total income tax benefit 8 2 Total reclassifications, net of taxes $ 31 $ 6 _________________________________________________________ (1) (Increases) decreases net realized investment gains on the consolidated statement of income. (2) (Increases) decreases income tax expense (benefit) 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
Earnings per Share (Table)	Mar. 31, 2024
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) 2024 2023 Basic and Diluted Net income, as reported $ 1,123 $ 975 Participating share-based awards — allocated income (8) (7) Net income available to common shareholders — basic and diluted $ 1,115 $ 968 Common Shares Basic Weighted average shares outstanding 229.0 231.7 Diluted Weighted average shares outstanding 229.0 231.7 Weighted average effects of dilutive securities — stock options and performance shares 3.0 2.7 Total 232.0 234.4 Net Income per Common Share Basic $ 4.87 $ 4.18 Diluted $ 4.80 $ 4.13

Share-Based Incentive Compens_2

Share-Based Incentive Compensation (Table)	3 Months Ended
Share-Based Incentive Compensation (Table)	Mar. 31, 2024
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, 2024: Stock Options Number Weighted Weighted Aggregate Vested at end of period (1) 6,832,710 $ 146.39 6.0 years $ 572 Exercisable at end of period 5,162,950 $ 132.57 5.1 years $ 504 _________________________________________________________ (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, 2024
Retirement Benefits [Abstract]
Summary of the components of net periodic benefit cost (benefit) for the Company's pension and postretirement benefit plans recognized in the consolidated statement of income [Table Text Block]	The following table summarizes the components of net periodic benefit cost (benefit) for the Company’s pension and postretirement benefit plans recognized in the consolidated statement of income for the three months ended March 31, 2024 and 2023. Pension Plans Postretirement Benefit Plans (for the three months ended March 31, in millions) 2024 2023 2024 2023 Net Periodic Benefit Cost (Benefit): Service cost $ 29 $ 27 $ — $ — Non-service cost (benefit): Interest cost on benefit obligation 43 44 1 1 Expected return on plan assets (75) (78) — — Amortization of unrecognized: Prior service benefit — — (1) (1) Net actuarial (gain) loss 2 — (2) (2) Total non-service cost (benefit) (30) (34) (2) (2) Net periodic benefit cost (benefit) $ (1) $ (7) $ (2) $ (2)
Consolidated statement of income line items impacted by service costs and non-service cost (benefit) [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, 2024 and 2023. Pension Plans Postretirement Benefit Plans (for the three months ended March 31, in millions) 2024 2023 2024 2023 Service Cost: Claims and claim adjustment expenses $ 11 $ 11 $ — $ — General and administrative expenses 18 16 — — Total service cost 29 27 — — Non-Service Cost (Benefit): Claims and claim adjustment expenses (12) (14) (1) (1) General and administrative expenses (18) (20) (1) (1) Total non-service cost (benefit) (30) (34) (2) (2) Net periodic benefit cost (benefit) $ (1) $ (7) $ (2) $ (2)

Leases (Table)

Leases (Table)	3 Months Ended
Leases (Table)	Mar. 31, 2024
Leases [Abstract]
Additional information regarding real estate operating leases [Table Text Block]	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) 2024 2023 Lease cost Operating leases $ 19 $ 19 Short-term leases (1) 1 1 Lease expense 20 20 Less: sublease income (2) — — Net lease cost $ 20 $ 20 Other information on operating leases Cash payments to settle a lease liability reported in cash flows $ 22 $ 21 Right-of-use assets obtained in exchange for new lease liabilities $ 10 $ 10 Weighted average discount rate 2.91 % 2.44 % Weighted average remaining lease term 4.1 years 4.4 years _________________________________________________________ (1) Leases with a term of twelve months or less are not recorded on the consolidated balance sheet. (2)

Basis of Presentation and Acc_3

Basis of Presentation and Accounting Policies (Details) - Corvus [Member] $ in Millions	Jan. 02, 2024 USD ($)
Business Acquisition
Approximate consideration transferred in acquisition of Corvus Insurance Holdings, Inc.	$ 427
Assets acquired from Corvus at acquisition date	478
Liabilities assumed as part of Corvus acquisition	51
Identifiable intangible assets and goodwill recorded as part of Corvus acquisition	390
Deferred tax asset recorded as a result of Corvus acquisition	$ 19

Basis of Presentation and Acc_4

Basis of Presentation and Accounting Policies (Details) - Tax Benefit $ in Millions	3 Months Ended
	Mar. 31, 2023 USD ($)
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Tax benefit due to the expiration of the statute of limitations with respect to a tax item impacted by the repeal of Internal Revenue Code Section 847, which related to the discounting of property-casualty loss reserves	$ 211

Segment Information (Details)

Segment Information (Details) $ in Millions	3 Months Ended
Segment Information (Details) $ in Millions	Mar. 31, 2024 USD ($) segment	Mar. 31, 2023 USD ($)
Segment reporting information
Number of reportable business segments \| segment	3
Premiums	$ 10,126	$ 8,854
Net investment income	846	663
Fee income	109	106
Other revenues	112	75
Net realized investment gains	35	6
Total revenues	11,228	9,704
Core income (loss)	1,096	970
Net realized investment gains, net of tax	27	5
Net income	1,123	975
Reportable Segments [Member]
Segment reporting information
Premiums	10,126	8,854
Net investment income	846	663
Fee income	109	106
Other revenues	112	75
Total segment revenues	11,193	9,698
Core income (loss)	1,179	1,046
Reportable Segments [Member] \| Business Insurance [Member]
Segment reporting information
Premiums	5,160	4,477
Net investment income	609	473
Fee income	101	99
Other revenues	77	47
Total segment revenues	5,947	5,096
Core income (loss)	764	756
Reportable Segments [Member] \| Business Insurance [Member] \| Domestic [Member]
Segment reporting information
Premiums	4,747	4,198
Reportable Segments [Member] \| Business Insurance [Member] \| Domestic [Member] \| Workers' compensation [Member]
Segment reporting information
Premiums	880	850
Reportable Segments [Member] \| Business Insurance [Member] \| Domestic [Member] \| Automobile [Member]
Segment reporting information
Premiums	860	761
Reportable Segments [Member] \| Business Insurance [Member] \| Domestic [Member] \| Commercial property [Member]
Segment reporting information
Premiums	873	709
Reportable Segments [Member] \| Business Insurance [Member] \| Domestic [Member] \| General liability [Member]
Segment reporting information
Premiums	847	760
Reportable Segments [Member] \| Business Insurance [Member] \| Domestic [Member] \| Commercial multi-peril [Member]
Segment reporting information
Premiums	1,270	1,100
Reportable Segments [Member] \| Business Insurance [Member] \| Domestic [Member] \| Other [Member]
Segment reporting information
Premiums	17	18
Reportable Segments [Member] \| Business Insurance [Member] \| International [Member]
Segment reporting information
Premiums	413	279
Reportable Segments [Member] \| Bond & Specialty Insurance [Member]
Segment reporting information
Premiums	956	875
Net investment income	90	73
Fee income	0	0
Other revenues	9	5
Total segment revenues	1,055	953
Core income (loss)	195	207
Reportable Segments [Member] \| Bond & Specialty Insurance [Member] \| Domestic [Member]
Segment reporting information
Premiums	822	758
Reportable Segments [Member] \| Bond & Specialty Insurance [Member] \| Domestic [Member] \| General liability [Member]
Segment reporting information
Premiums	426	398
Reportable Segments [Member] \| Bond & Specialty Insurance [Member] \| Domestic [Member] \| Fidelity and surety [Member]
Segment reporting information
Premiums	340	306
Reportable Segments [Member] \| Bond & Specialty Insurance [Member] \| Domestic [Member] \| Other [Member]
Segment reporting information
Premiums	56	54
Reportable Segments [Member] \| Bond & Specialty Insurance [Member] \| International [Member]
Segment reporting information
Premiums	134	117
Reportable Segments [Member] \| Personal Insurance [Member]
Segment reporting information
Premiums	4,010	3,502
Net investment income	147	117
Fee income	8	7
Other revenues	26	23
Total segment revenues	4,191	3,649
Core income (loss)	220	83
Reportable Segments [Member] \| Personal Insurance [Member] \| Domestic [Member]
Segment reporting information
Premiums	3,846	3,348
Reportable Segments [Member] \| Personal Insurance [Member] \| Domestic [Member] \| Automobile [Member]
Segment reporting information
Premiums	1,874	1,624
Reportable Segments [Member] \| Personal Insurance [Member] \| Domestic [Member] \| Homeowners and Other [Member]
Segment reporting information
Premiums	1,972	1,724
Reportable Segments [Member] \| Personal Insurance [Member] \| International [Member]
Segment reporting information
Premiums	164	154
Other [Member]
Segment reporting information
Core income (loss)	(83)	(76)
After-tax interest expense	$ 77	$ 70

Segment Information (Details) -

Segment Information (Details) - Assets by Segment - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Assets by segment
Total assets	$ 127,410	$ 125,978
Reportable Segments [Member]
Assets by segment
Total assets	126,532	125,115
Reportable Segments [Member] \| Business Insurance [Member]
Assets by segment
Total assets	94,393	93,565
Reportable Segments [Member] \| Bond & Specialty Insurance [Member]
Assets by segment
Total assets	12,136	11,478
Reportable Segments [Member] \| Personal Insurance [Member]
Assets by segment
Total assets	20,003	20,072
Other assets [Member]
Assets by segment
Total assets	$ 878	$ 863

Investments (Details) - Investm

Investments (Details) - Investment Information, Debt Securities - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Investment disclosure details
Fixed maturities, amortized cost	$ 82,712		$ 81,781
Allowance for expected credit losses	3		5
Gross unrealized gains	246		471
Gross unrealized losses	4,964		4,440
Fixed maturities, at fair value	77,991		77,807
Proceeds from sales of fixed maturities classified as available for sale	942	$ 2,364
Gross realized gains	2	17
Gross realized losses	39	27
U.S. Treasury securities and obligations of U.S. government and government agencies and authorities [Member]
Investment disclosure details
Fixed maturities, amortized cost	6,489		6,591
Allowance for expected credit losses	0		0
Gross unrealized gains	1		8
Gross unrealized losses	250		231
Fixed maturities, at fair value	6,240		6,368
Obligations of U.S. states, municipalities and political subdivisions [Member]
Investment disclosure details
Fixed maturities, amortized cost	29,665		30,294
Allowance for expected credit losses	0		0
Gross unrealized gains	73		154
Gross unrealized losses	2,226		1,942
Fixed maturities, at fair value	27,512		28,506
Obligations of U.S. states, municipalities and political subdivisions, local general obligation [Member]
Investment disclosure details
Fixed maturities, amortized cost	18,138		18,374
Allowance for expected credit losses	0		0
Gross unrealized gains	41		90
Gross unrealized losses	1,455		1,265
Fixed maturities, at fair value	16,724		17,199
Obligations of U.S. states, municipalities and political subdivisions, revenue [Member]
Investment disclosure details
Fixed maturities, amortized cost	9,419		9,748
Allowance for expected credit losses	0		0
Gross unrealized gains	27		52
Gross unrealized losses	700		616
Fixed maturities, at fair value	8,746		9,184
Obligations of U.S. states, municipalities and political subdivisions, state general obligation [Member]
Investment disclosure details
Fixed maturities, amortized cost	1,156		1,209
Allowance for expected credit losses	0		0
Gross unrealized gains	3		7
Gross unrealized losses	67		59
Fixed maturities, at fair value	1,092		1,157
Obligations of U.S. states, municipalities and political subdivisions, pre-refunded [Member]
Investment disclosure details
Fixed maturities, amortized cost	952		963
Allowance for expected credit losses	0		0
Gross unrealized gains	2		5
Gross unrealized losses	4		2
Fixed maturities, at fair value	950		966
Debt securities issued by foreign governments [Member]
Investment disclosure details
Fixed maturities, amortized cost	970		1,035
Allowance for expected credit losses	0		0
Gross unrealized gains	1		2
Gross unrealized losses	32		31
Fixed maturities, at fair value	939		1,006
Mortgage-backed securities, collateralized mortgage obligations and pass-through securities [Member]
Investment disclosure details
Fixed maturities, amortized cost	9,076		7,874
Allowance for expected credit losses	0		0
Gross unrealized gains	68		120
Gross unrealized losses	224		176
Fixed maturities, at fair value	8,920		7,818
Corporate and all other bonds [Member]
Investment disclosure details
Fixed maturities, amortized cost	36,512		35,987
Allowance for expected credit losses	3	$ 4	5	$ 3
Gross unrealized gains	103		187
Gross unrealized losses	2,232		2,060
Fixed maturities, at fair value	$ 34,380		$ 34,109

Investments (Details) - Inves_2

Investments (Details) - Investment Information, Equity Securities - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Investment disclosure details
Equity securities, cost	$ 557		$ 553
Gross gains	145		96
Gross losses	13		41
Equity securities, at fair value	689		608
Net recognized gains on equity securities still held	79	$ 17
Common stock [Member]
Investment disclosure details
Equity securities, cost	512		508
Gross gains	142		93
Gross losses	13		41
Equity securities, at fair value	641		560
Non-redeemable preferred stock [Member]
Investment disclosure details
Equity securities, cost	45		45
Gross gains	3		3
Gross losses	0		0
Equity securities, at fair value	$ 48		$ 48

Investments (Details) - Inves_3

Investments (Details) - Investment Information, Losses - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Investment disclosure details
Continuous unrealized loss position, less than 12 months, fair value	$ 16,021	$ 7,993
Continuous unrealized loss position, less than 12 months, gross unrealized losses	142	56
Continuous unrealized loss position, 12 months or longer, fair value	46,120	45,976
Continuous unrealized loss position, 12 months or longer, gross unrealized losses	4,822	4,384
Continuous unrealized loss position, total, fair value	62,141	53,969
Continuous unrealized loss position, total, gross unrealized losses	4,964	4,440
Unrealized investment losses on fixed maturity investments for which fair value is less than 80% of amortized cost, 3 months or less	309	1
Unrealized investment losses on fixed maturity investments for which fair value is less than 80% of amortized cost greater than 3 months, 6 months or less	2	5
Unrealized investment losses on fixed maturity investments for which fair value is less than 80% of amortized cost, greater than 6 months, 12 months or less	9	53
Unrealized investment losses on fixed maturity investments for which fair value is less than 80% of amortized cost, greater than 12 months	731	667
Unrealized investment losses on fixed maturity investments for which fair value is less than 80% of amortized cost, total	1,051	726
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	2,866	1,864
Continuous unrealized loss position, less than 12 months, gross unrealized losses	17	7
Continuous unrealized loss position, 12 months or longer, fair value	2,869	2,985
Continuous unrealized loss position, 12 months or longer, gross unrealized losses	233	224
Continuous unrealized loss position, total, fair value	5,735	4,849
Continuous unrealized loss position, total, gross unrealized losses	250	231
Unrealized investment losses on fixed maturity investments for which fair value is less than 80% of amortized cost, 3 months or less	0	0
Unrealized investment losses on fixed maturity investments for which fair value is less than 80% of amortized cost greater than 3 months, 6 months or less	0	0
Unrealized investment losses on fixed maturity investments for which fair value is less than 80% of amortized cost, greater than 6 months, 12 months or less	0	0
Unrealized investment losses on fixed maturity investments for which fair value is less than 80% of amortized cost, greater than 12 months	0	0
Unrealized investment losses on fixed maturity investments for which fair value is less than 80% of amortized cost, total	0	0
Obligations of U.S. states, municipalities and political subdivisions [Member]
Investment disclosure details
Continuous unrealized loss position, less than 12 months, fair value	6,958	3,868
Continuous unrealized loss position, less than 12 months, gross unrealized losses	67	31
Continuous unrealized loss position, 12 months or longer, fair value	15,198	14,351
Continuous unrealized loss position, 12 months or longer, gross unrealized losses	2,159	1,911
Continuous unrealized loss position, total, fair value	22,156	18,219
Continuous unrealized loss position, total, gross unrealized losses	2,226	1,942
Unrealized investment losses on fixed maturity investments for which fair value is less than 80% of amortized cost, 3 months or less	224	0
Unrealized investment losses on fixed maturity investments for which fair value is less than 80% of amortized cost greater than 3 months, 6 months or less	0	2
Unrealized investment losses on fixed maturity investments for which fair value is less than 80% of amortized cost, greater than 6 months, 12 months or less	8	31
Unrealized investment losses on fixed maturity investments for which fair value is less than 80% of amortized cost, greater than 12 months	708	642
Unrealized investment losses on fixed maturity investments for which fair value is less than 80% of amortized cost, total	940	675
Debt securities issued by foreign governments [Member]
Investment disclosure details
Continuous unrealized loss position, less than 12 months, fair value	134	30
Continuous unrealized loss position, less than 12 months, gross unrealized losses	1	0
Continuous unrealized loss position, 12 months or longer, fair value	696	763
Continuous unrealized loss position, 12 months or longer, gross unrealized losses	31	31
Continuous unrealized loss position, total, fair value	830	793
Continuous unrealized loss position, total, gross unrealized losses	32	31
Unrealized investment losses on fixed maturity investments for which fair value is less than 80% of amortized cost, 3 months or less	0	0
Unrealized investment losses on fixed maturity investments for which fair value is less than 80% of amortized cost greater than 3 months, 6 months or less	0	0
Unrealized investment losses on fixed maturity investments for which fair value is less than 80% of amortized cost, greater than 6 months, 12 months or less	0	0
Unrealized investment losses on fixed maturity investments for which fair value is less than 80% of amortized cost, greater than 12 months	0	0
Unrealized investment losses on fixed maturity investments for which fair value is less than 80% of amortized cost, total	0	0
Mortgage-backed securities, collateralized mortgage obligations and pass-through securities [Member]
Investment disclosure details
Continuous unrealized loss position, less than 12 months, fair value	3,106	1,215
Continuous unrealized loss position, less than 12 months, gross unrealized losses	29	9
Continuous unrealized loss position, 12 months or longer, fair value	1,689	1,433
Continuous unrealized loss position, 12 months or longer, gross unrealized losses	195	167
Continuous unrealized loss position, total, fair value	4,795	2,648
Continuous unrealized loss position, total, gross unrealized losses	224	176
Unrealized investment losses on fixed maturity investments for which fair value is less than 80% of amortized cost, 3 months or less	44	0
Unrealized investment losses on fixed maturity investments for which fair value is less than 80% of amortized cost greater than 3 months, 6 months or less	0	0
Unrealized investment losses on fixed maturity investments for which fair value is less than 80% of amortized cost, greater than 6 months, 12 months or less	0	0
Unrealized investment losses on fixed maturity investments for which fair value is less than 80% of amortized cost, greater than 12 months	0	0
Unrealized investment losses on fixed maturity investments for which fair value is less than 80% of amortized cost, total	44	0
Corporate and all other bonds [Member]
Investment disclosure details
Continuous unrealized loss position, less than 12 months, fair value	2,957	1,016
Continuous unrealized loss position, less than 12 months, gross unrealized losses	28	9
Continuous unrealized loss position, 12 months or longer, fair value	25,668	26,444
Continuous unrealized loss position, 12 months or longer, gross unrealized losses	2,204	2,051
Continuous unrealized loss position, total, fair value	28,625	27,460
Continuous unrealized loss position, total, gross unrealized losses	2,232	2,060
Unrealized investment losses on fixed maturity investments for which fair value is less than 80% of amortized cost, 3 months or less	41	1
Unrealized investment losses on fixed maturity investments for which fair value is less than 80% of amortized cost greater than 3 months, 6 months or less	2	3
Unrealized investment losses on fixed maturity investments for which fair value is less than 80% of amortized cost, greater than 6 months, 12 months or less	1	22
Unrealized investment losses on fixed maturity investments for which fair value is less than 80% of amortized cost, greater than 12 months	23	25
Unrealized investment losses on fixed maturity investments for which fair value is less than 80% of amortized cost, total	$ 67	$ 51

Investments (Details) - Allowan

Investments (Details) - Allowance for Expected Credit Losses - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Allowance for expected credit losses [Roll Forward]
Allowance for expected credit losses on fixed maturities classified as available-for-sale, balance, beginning of period	$ 5
Allowance for expected credit losses on fixed maturities classified as available-for-sale, balance, end of period	3
Total net impairment charges, including credit impairments, reported in net realized investment gains in the consolidated statement of income	$ 3	$ 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%	1%
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%	1%
Corporate and all other bonds [Member]
Allowance for expected credit losses [Roll Forward]
Allowance for expected credit losses on fixed maturities classified as available-for-sale, balance, beginning of period	$ 5	$ 3
Additions for expected credit losses on securities where no credit losses were previously recognized	3	0
Additions for expected credit losses on securities where credit losses were previously recognized	0	1
Reductions due to sales/defaults of credit-impaired securities	(5)	0
Reductions for impairments of securities which the Company intends to sell or more likely than not will be required to sell	0	0
Allowance for expected credit losses on fixed maturities classified as available-for-sale, balance, end of period	$ 3	$ 4

Investments (Details) - Other I

Investments (Details) - Other Investments	3 Months Ended
Investments (Details) - Other Investments	Mar. 31, 2024
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)	Mar. 31, 2024	Dec. 31, 2023
Fair Value Disclosures [Abstract]
Percent of fixed maturities for which a pricing service estimates fair value	99%	99%

Fair Value Measurements (Deta_2

Fair Value Measurements (Details) - Fair Value Hierarchy - Recurring basis [Member] - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
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	$ 78,698	$ 78,433
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	77,991	77,807
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	6,240	6,368
Obligations of U.S. 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	27,512	28,506
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	939	1,006
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	8,920	7,818
Corporate and all other 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	34,380	34,109
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	689	608
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	641	560
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	48	48
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	18	18
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	6,907	6,955
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	6,240	6,368
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	6,240	6,368
Level 1 [Member] \| Obligations of U.S. 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] \| Corporate and all other bonds [Member]
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured
Total invested assets measured on a recurring basis	0	0
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	649	569
Level 1 [Member] \| 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	634	553
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	16
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	18	18
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	71,478	71,183
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	71,475	71,181
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 U.S. 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	27,512	28,506
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	939	1,006
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	8,899	7,818
Level 2 [Member] \| Corporate and all other 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	34,125	33,851
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	3	2
Level 2 [Member] \| 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	3	2
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	313	295
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	276	258
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 U.S. 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 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	21	0
Level 3 [Member] \| Corporate and all other 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	255	258
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	37	37
Level 3 [Member] \| 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	7	7
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	30	30
Level 3 [Member] \| Investment in non-public common and preferred equity securities where the fair value estimate is determined either internally or by an external fund manager [Member]
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured
Total invested assets measured on a recurring basis	37	37
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	$ 0	$ 0

Fair Value Measurements (Deta_3

Fair Value Measurements (Details) - Financial Instruments - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Financial Instruments
Short-term securities	$ 4,682	$ 5,137
Carrying Value [Member]
Financial Instruments
Short-term securities	4,682	5,137
Debt	7,932	7,931
Commercial paper	100	100
Fair Value [Member]
Financial Instruments
Short-term securities	4,682	5,137
Debt	7,406	7,645
Commercial paper	100	100
Fair Value [Member] \| Level 1 [Member]
Financial Instruments
Short-term securities	999	1,171
Debt	0	0
Commercial paper	0	0
Fair Value [Member] \| Level 2 [Member]
Financial Instruments
Short-term securities	3,634	3,912
Debt	7,406	7,645
Commercial paper	100	100
Fair Value [Member] \| Level 3 [Member]
Financial Instruments
Short-term securities	49	54
Debt	0	0
Commercial paper	$ 0	$ 0

Allowance for Expected Credit_3

Allowance for Expected Credit Losses (Details) - Changes in the Allowance for Expected Credit Losses on Premiums Receivable - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Credit Loss [Abstract]
Premiums receivable (net of allowance for expected credit losses), balance, beginning of period	$ 10,282	$ 8,922
Premiums receivable (net of allowance for expected credit losses), balance, end of period	10,829	9,483
Premiums receivable, allowance for expected credit losses [Roll Forward]
Premiums receivable, allowance for expected credit losses, beginning balance	69	77
Current period change for expected credit losses	12	10
Write-offs of uncollectible premiums receivable	13	10
Premiums receivable, allowance for expected credit losses, ending balance	$ 68	$ 77

Allowance for Expected Credit_4

Allowance for Expected Credit Losses (Details) - Changes in the Allowance for Estimated Uncollectible Reinsurance - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Credit Loss [Abstract]
Reinsurance recoverables (net of allowance for estimated uncollectible reinsurance), balance, beginning of period	$ 8,143	$ 8,063
Reinsurance recoverables (net of allowance for estimated uncollectible reinsurance), balance, end of period	8,100	8,091
Reinsurance recoverables, allowance for uncollectible reinsurance [Roll Forward]
Reinsurance recoverables, allowance for uncollectible reinsurance, beginning balance	118	132
Current period change for estimated uncollectible reinsurance	(1)	(1)
Write-offs of uncollectible reinsurance recoverables	0	0
Reinsurance recoverables, allowance for uncollectible reinsurance, ending balance	$ 117	$ 131

Allowance for Expected Credit_5

Allowance for Expected Credit Losses (Details) - Narrative - Reinsurer Concentration Risk [Member] $ in Millions	3 Months Ended
	Mar. 31, 2024 USD ($)
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	$ 5,700
Concentration risk percentage	87%
Reinsurance Recoverables [Member] \| Reinsurer Group Not Rated by A.M. Best [Member]
Reinsurance recoverables, credit quality indicator
Concentration risk percentage	13%
Reinsurance Recoverables [Member] \| Captive Insurance Companies [Member]
Reinsurance recoverables, credit quality indicator
Concentration risk percentage	6%
Reinsurance Recoverables [Member] \| Voluntary Pools [Member]
Reinsurance recoverables, credit quality indicator
Concentration risk percentage	1%
Reinsurance Recoverables [Member] \| Other Companies [Member]
Reinsurance recoverables, credit quality indicator
Concentration risk percentage	6%
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	94%

Allowance for Expected Credit_6

Allowance for Expected Credit Losses (Details) - Changes in the Allowance for Expected Credit Losses on Contractholder Receivables (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Credit Loss [Abstract]
Contractholder receivables (net of the allowance for expected credit losses), balance, beginning of period	$ 3,249	$ 3,579
Contractholder receivables (net of the allowance for expected credit losses), balance, end of period	3,266	3,598
Contractholder receivables, allowance for expected credit losses [Roll Forward]
Contractholder receivables, allowance for expected credit losses, beginning balance	20	17
Current period change for expected credit losses	(1)	2
Write-offs of uncollectible contractholder receivables	0	0
Contractholder receivables, allowance for expected credit losses, ending balance	$ 19	$ 19

Goodwill and Other Intangible_3

Goodwill and Other Intangible Assets (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Goodwill by segment
Goodwill	$ 4,251	$ 3,976
Reportable Segments [Member] \| Business Insurance [Member]
Goodwill by segment
Goodwill	2,579	2,585
Reportable Segments [Member] \| Bond & Specialty Insurance [Member]
Goodwill by segment
Goodwill	835	550
Reportable Segments [Member] \| Bond & Specialty Insurance [Member] \| Corvus [Member]
Goodwill by segment
Goodwill	285
Amount of goodwill expected to be deductible for tax purposes	0
Reportable Segments [Member] \| Personal Insurance [Member]
Goodwill by segment
Goodwill	811	815
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
	Jan. 02, 2024	Mar. 31, 2024	Dec. 31, 2023
Other intangible assets by major asset class
Intangible assets subject to amortization, gross carrying amount		$ 408	$ 304
Intangible assets subject to amortization, accumulated amortization		258	253
Intangible assets subject to amortization, net		150	51
Intangible assets not subject to amortization		226	226
Total other intangible assets, gross carrying amount		634	530
Total other intangible assets, net		376	277
Corvus [Member]
Other intangible assets by major asset class
Intangible assets recorded in connection with acquisition of Corvus	$ 105
Weighted average amortization period of intangible assets recorded in connection with acquisition of Corvus	13 years
Customer-related [Member]
Other intangible assets by major asset class
Intangible assets subject to amortization, gross carrying amount		186	100
Intangible assets subject to amortization, accumulated amortization		63	59
Intangible assets subject to amortization, net		123	41
Customer-related [Member] \| Corvus [Member]
Other intangible assets by major asset class
Intangible assets recorded in connection with acquisition of Corvus	$ 87	87
Weighted average amortization period of intangible assets recorded in connection with acquisition of Corvus	14 years
Contract-based [Member]
Other intangible assets by major asset class
Intangible assets subject to amortization, gross carrying amount		204	204
Intangible assets subject to amortization, accumulated amortization		194	194
Intangible assets subject to amortization, net		10	$ 10
Marketing-related [Member]
Other intangible assets by major asset class
Intangible assets subject to amortization, gross carrying amount		18
Intangible assets subject to amortization, accumulated amortization		1
Intangible assets subject to amortization, net		17
Marketing-related [Member] \| Corvus [Member]
Other intangible assets by major asset class
Intangible assets recorded in connection with acquisition of Corvus	$ 18	$ 18
Weighted average amortization period of intangible assets recorded in connection with acquisition of Corvus	7 years

Insurance Claim Reserves (Detai

Insurance Claim Reserves (Details) - Reserve Detail for Claims and Claim Adjustment Expenses - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
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	$ 61,627
Claims and claim adjustment expense reserves at end of period	62,487
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	61,621	$ 58,643
Reinsurance recoverables on unpaid losses	7,817	7,790
Net reserves at beginning of year	53,804	50,853
Estimated claims and claim adjustment expenses for claims arising in the current year	6,679	6,025
Estimated decrease in claims and claim adjustment expenses for claims arising in prior years	(49)	(90)
Total increases	6,630	5,935
Claims and claim adjustment expense payments for claims arising in current year	1,275	1,177
Claims and claim adjustment expense payments for claims arising in prior years	4,435	4,382
Total payments	5,710	5,559
Unrealized foreign exchange (gain) loss	(61)	28
Net reserves at end of period	54,663	51,257
Reinsurance recoverables on unpaid losses	7,819	7,801
Claims and claim adjustment expense reserves at end of period	62,482	$ 59,058
Amount of increase in gross claims and claim adjustment expense reserves	861
Amount of increase in reinsurance recoverables on unpaid losses	2
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	6
Claims and claim adjustment expense reserves at end of period	$ 5

Insurance Claim Reserves (Det_2

Insurance Claim Reserves (Details) - Prior Year Reserve Development - Property-casualty [Member] - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Liability for claims and claim adjustment expense
Net favorable prior year reserve development included in estimated claims and claim adjustment expenses incurred for claims arising in prior years	$ 49	$ 90
Net favorable prior year reserve development impacting the Company's results of operations	91	105
Accretion expense	11	11
Business Insurance [Member]
Liability for claims and claim adjustment expense
Net favorable prior year reserve development impacting the Company's results of operations	0	19
Bond & Specialty Insurance [Member]
Liability for claims and claim adjustment expense
Net favorable prior year reserve development impacting the Company's results of operations	24	58
Personal Insurance [Member]
Liability for claims and claim adjustment expense
Net favorable prior year reserve development impacting the Company's results of operations	$ 67	$ 28

Other Comprehensive Income (L_3

Other Comprehensive Income (Loss) and Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Accumulated other comprehensive income (loss) [Roll Forward]
Balance, beginning of period	$ 24,921
Other comprehensive income (loss), net of taxes	(660)	$ 1,059
Balance, end of period	25,022	23,052
Pre-tax components of other comprehensive income (loss) and the related income tax expense (benefit)
Other comprehensive income (loss), before income taxes	(822)	1,342
Income tax expense (benefit)	(162)	283
Other comprehensive income (loss), net of taxes	(660)	1,059
Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated other comprehensive income (loss) [Roll Forward]
Balance, beginning of period	(4,471)	(6,445)
Other comprehensive income (loss) before reclassifications	(691)
Amounts reclassified from accumulated other comprehensive income (loss), net of tax	31
Other comprehensive income (loss), net of taxes	(660)	1,059
Balance, end of period	(5,131)	(5,386)
Pre-tax components of other comprehensive income (loss) and the related income tax expense (benefit)
Other comprehensive income (loss), before income taxes	(822)	1,342
Income tax expense (benefit)	(162)	283
Other comprehensive income (loss), net of taxes	(660)	1,059
Changes in Net Unrealized Gains (Losses) on Investment Securities Having No Credit Losses Recognized in the Consolidated Statement of Income [Member]
Accumulated other comprehensive income (loss) [Roll Forward]
Balance, beginning of period	(3,309)
Other comprehensive income (loss) before reclassifications	(626)
Amounts reclassified from accumulated other comprehensive income (loss), net of tax	32
Other comprehensive income (loss), net of taxes	(594)	1,030
Balance, end of period	(3,903)
Pre-tax components of other comprehensive income (loss) and the related income tax expense (benefit)
Other comprehensive income (loss), before income taxes	(752)	1,308
Income tax expense (benefit)	(158)	278
Other comprehensive income (loss), net of taxes	(594)	1,030
Changes in Net Unrealized Gains (Losses) on Investment Securities Having Credit Losses Recognized in the Consolidated Statement of Income [Member]
Accumulated other comprehensive income (loss) [Roll Forward]
Balance, beginning of period	180
Other comprehensive income (loss) before reclassifications	2
Amounts reclassified from accumulated other comprehensive income (loss), net of tax	0
Other comprehensive income (loss), net of taxes	2	0
Balance, end of period	182
Pre-tax components of other comprehensive income (loss) and the related income tax expense (benefit)
Other comprehensive income (loss), before income taxes	2	0
Income tax expense (benefit)	0	0
Other comprehensive income (loss), net of taxes	2	0
Net Benefit Plan Assets and Obligations Recognized in Shareholders' Equity [Member]
Accumulated other comprehensive income (loss) [Roll Forward]
Balance, beginning of period	(458)
Other comprehensive income (loss) before reclassifications	0
Amounts reclassified from accumulated other comprehensive income (loss), net of tax	(1)
Other comprehensive income (loss), net of taxes	(1)	(2)
Balance, end of period	(459)
Pre-tax components of other comprehensive income (loss) and the related income tax expense (benefit)
Other comprehensive income (loss), before income taxes	(1)	(3)
Income tax expense (benefit)	0	(1)
Other comprehensive income (loss), net of taxes	(1)	(2)
Net Unrealized Foreign Currency Translation [Member]
Accumulated other comprehensive income (loss) [Roll Forward]
Balance, beginning of period	(884)
Other comprehensive income (loss) before reclassifications	(67)
Amounts reclassified from accumulated other comprehensive income (loss), net of tax	0
Other comprehensive income (loss), net of taxes	(67)	31
Balance, end of period	(951)
Pre-tax components of other comprehensive income (loss) and the related income tax expense (benefit)
Other comprehensive income (loss), before income taxes	(71)	37
Income tax expense (benefit)	(4)	6
Other comprehensive income (loss), net of taxes	$ (67)	$ 31

Other Comprehensive Income (L_4

Other Comprehensive Income (Loss) and Accumulated Other Comprehensive Income (Loss) (Details) - Reclassifications - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Reclassification Adjustment out of Accumulated Other Comprehensive Income (Loss)
Reclassification adjustment impacting net realized investment gains on the consolidated statement of income	$ (35)	$ (6)
Reclassification adjustment impacting claims and claim adjustment expenses (benefit) on the consolidated statement of income	6,656	5,959
Reclassification adjustment impacting general and administrative expenses (benefit) on the consolidated statement of income	1,406	1,267
Total reclassifications	(1,370)	(928)
Income tax (expense) benefit	(247)	47
Amounts reclassified from accumulated other comprehensive income (loss), net of taxes	(1,123)	(975)
Accumulated Other Comprehensive Income (Loss) [Member] \| Reclassification out of Accumulated Other Comprehensive Income (Loss) [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income (Loss)
Total reclassifications	39	8
Income tax (expense) benefit	8	2
Amounts reclassified from accumulated other comprehensive income (loss), net of taxes	31	6
Changes in Net Unrealized Gains (Losses) on Investment Securities Having No Credit Losses Recognized in the Consolidated Statement of Income [Member] \| Reclassification out of Accumulated Other Comprehensive Income (Loss) [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income (Loss)
Reclassification adjustment impacting net realized investment gains on the consolidated statement of income	40	11
Income tax (expense) benefit	8	2
Amounts reclassified from accumulated other comprehensive income (loss), net of taxes	32	9
Changes in Net Unrealized Gains (Losses) on Investment Securities Having Credit Losses Recognized in the Consolidated Statement of Income [Member] \| Reclassification out of Accumulated Other Comprehensive Income (Loss) [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income (Loss)
Reclassification adjustment impacting net realized investment gains on the consolidated statement of income	0	0
Income tax (expense) benefit	0	0
Amounts reclassified from accumulated other comprehensive income (loss), net of taxes	0	0
Net Benefit Plan Assets and Obligations Recognized in Shareholders' Equity [Member] \| Reclassification out of Accumulated Other Comprehensive Income (Loss) [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income (Loss)
Reclassification adjustment impacting claims and claim adjustment expenses (benefit) on the consolidated statement of income	0	(1)
Reclassification adjustment impacting general and administrative expenses (benefit) on the consolidated statement of income	(1)	(2)
Total reclassifications	(1)	(3)
Income tax (expense) benefit	0	0
Amounts reclassified from accumulated other comprehensive income (loss), net of taxes	(1)	(3)
Net Unrealized Foreign Currency Translation [Member] \| Reclassification out of Accumulated Other Comprehensive Income (Loss) [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income (Loss)
Reclassification adjustment impacting net realized investment gains on the consolidated statement of income	0	0
Income tax (expense) benefit	0	0
Amounts reclassified from accumulated other comprehensive income (loss), 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, 2024 USD ($) $ / shares shares
Treasury Stock Transactions, Excluding Value of Shares Reissued [Abstract]
Number of shares repurchased under share repurchase authorization (in shares) \| shares	1.2
Cost of shares repurchased under share repurchase authorization	$ 250
Average cost per share repurchased under share repurchase authorization (in dollars per share) \| $ / shares	$ 217.31
Number of shares acquired to cover tax withholding costs and exercise costs (in shares) \| shares	0.6
Cost of shares acquired to cover tax withholding costs and exercise costs	$ 138
Net excise tax included in cost of treasury stock acquired	0
Remaining capacity under share repurchase authorization	$ 5,790

Earnings per Share (Details)

Earnings per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Earnings Per Share Reconciliation [Abstract]
Net income	$ 1,123	$ 975
Participating share-based awards — allocated income	(8)	(7)
Net income available to common shareholders -- basic	1,115	968
Net income available to common shareholders -- diluted	$ 1,115	$ 968
Weighted average shares outstanding, basic (in shares)	229	231.7
Weighted average effects of dilutive securities - stock options and performance shares (in shares)	3	2.7
Weighted average shares outstanding, diluted (in shares)	232	234.4
Net income per common share, basic (in dollars per share)	$ 4.87	$ 4.18
Net income per common share, diluted (in dollars per share)	$ 4.80	$ 4.13

Share-Based Incentive Compens_3

Share-Based Incentive Compensation (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Share-Based Payment Arrangement [Abstract]
Stock options vested at end of period, number (in shares)	6,832,710
Stock options vested at end of period, weighted average exercise price (in dollars per share)	$ 146.39
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	$ 572
Stock options exercisable at end of period, number (in shares)	5,162,950
Stock options exercisable at end of period, weighted average exercise price (in dollars per share)	$ 132.57
Stock options exercisable at end of period, weighted average contractual life remaining (in years)	5 years 1 month 6 days
Stock options exercisable at end of period, aggregate intrinsic value	$ 504
Total compensation cost recognized in earnings for all share-based incentive compensation awards	79	$ 69
Tax benefit recognized in the consolidated statement of income related to compensation costs	12	$ 11
Total unrecognized compensation cost related to all nonvested share-based incentive compensation awards	$ 380
Weighted-average period of recognition for unrecognized compensation cost (in years)	2 years 2 months 12 days

Pension Plans, Retirement Ben_3

Pension Plans, Retirement Benefits and Savings Plans (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Pension Plans [Member]
Defined benefit plan disclosure
Service cost	$ 29	$ 27
Interest cost on benefit obligation	43	44
Expected return on plan assets	(75)	(78)
Net periodic benefit cost (benefit), amortization of unrecognized prior service benefit	0	0
Net periodic benefit cost (benefit), amortization of unrecognized net actuarial (gain) loss	2	0
Total non-service cost (benefit)	(30)	(34)
Net periodic benefit cost (benefit)	(1)	(7)
Pension Plans [Member] \| Claims and claim adjustment expenses [Member]
Defined benefit plan disclosure
Service cost	11	11
Total non-service cost (benefit)	(12)	(14)
Pension Plans [Member] \| General and administrative expenses [Member]
Defined benefit plan disclosure
Service cost	18	16
Total non-service cost (benefit)	(18)	(20)
Postretirement Benefit Plans [Member]
Defined benefit plan disclosure
Service cost	0	0
Interest cost on benefit obligation	1	1
Expected return on plan assets	0	0
Net periodic benefit cost (benefit), amortization of unrecognized prior service benefit	(1)	(1)
Net periodic benefit cost (benefit), amortization of unrecognized net actuarial (gain) loss	(2)	(2)
Total non-service cost (benefit)	(2)	(2)
Net periodic benefit cost (benefit)	(2)	(2)
Postretirement Benefit Plans [Member] \| Claims and claim adjustment expenses [Member]
Defined benefit plan disclosure
Service cost	0	0
Total non-service cost (benefit)	(1)	(1)
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
Leases (Details) - USD ($) $ in Millions	Mar. 31, 2024	Mar. 31, 2023
Leases [Abstract]
Operating leases	$ 19	$ 19
Short-term leases	1	1
Lease expense	20	20
Less: sublease income	0	0
Net lease cost	20	20
Cash payments to settle a lease liability reported in cash flows	22	21
Right-of-use assets obtained in exchange for new lease liabilities	$ 10	$ 10
Weighted average discount rate (percent)	2.91%	2.44%
Weighted average remaining lease term (in years)	4 years 1 month 6 days	4 years 4 months 24 days

Contingencies, Commitments an_2

Contingencies, Commitments and Guarantees (Details) - Commitments - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Contingencies, Commitments and Guarantees [Abstract]
Unfunded commitments to private equity limited partnerships, real estate partnerships and other investments	$ 1,590	$ 2,050

Contingencies, Commitments an_3

Contingencies, Commitments and Guarantees (Details) - Guarantees $ in Millions	Mar. 31, 2024 USD ($)
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