TRAVELERS COMPANIES, INC., 10-Q filed on 4/17/2024
Quarterly Report
v3.24.1.u1
Cover Page - shares
 3 Months Ended
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  
v3.24.1.u1
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) 229.0 231.7
Diluted (in shares) 232.0 234.4
Cash dividends declared per common share (in dollars per share) $ 1.00 $ 0.93
v3.24.1.u1
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
v3.24.1.u1
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
v3.24.1.u1
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) 1,750.0 1,750.0
Common stock, shares issued (in shares) 229.0 228.2
Common stock, shares outstanding (in shares) 229.0 228.2
Treasury stock, at cost (in shares) 561.0 559.2
v3.24.1.u1
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           231.0
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)           2.0
Balance, end of period (in shares) at Mar. 31, 2024 229.0         229.0
v3.24.1.u1
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
v3.24.1.u1
Basis of Presentation and Accounting Policies
 3 Months Ended
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.
v3.24.1.u1
Segment Information
 3 Months Ended
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
Insurance		Bond & Specialty
Insurance		Personal
Insurance		Total
Reportable
Segments
2024    
Premiums$5,160 $956 $4,010 $10,126 
Net investment income609 90 147 846 
Fee income101 — 8 109 
Other revenues77 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 income473 73 117 663 
Fee income99 — 7 106 
Other revenues47 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
March 31,
(in millions)20242023
Revenue reconciliation  
Earned premiums  
Business Insurance:  
Domestic:  
Workers’ compensation$880 $850 
Commercial automobile860 761 
Commercial property873 709 
General liability847 760 
Commercial multi-peril1,270 1,100 
Other17 18 
Total Domestic4,747 4,198 
International413 279 
Total Business Insurance5,160 4,477 
Bond & Specialty Insurance:  
Domestic:  
Fidelity and surety340 306 
General liability426 398 
Other56 54 
Total Domestic822 758 
International134 117 
Total Bond & Specialty Insurance956 875 
Personal Insurance:  
Domestic:  
Automobile1,874 1,624 
Homeowners and Other1,972 1,724 
Total Domestic3,846 3,348 
International164 154 
Total Personal Insurance4,010 3,502 
Total earned premiums10,126 8,854 
Net investment income846 663 
Fee income109 106 
Other revenues112 75 
Total segment revenues11,193 9,698 
Net realized investment gains35 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 income1,096 970 
Net realized investment gains27 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,
2024		December 31,
2023
Asset reconciliation  
Business Insurance$94,393 $93,565 
Bond & Specialty Insurance12,136 11,478 
Personal Insurance20,003 20,072 
Total assets by reportable segment126,532 125,115 
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.
v3.24.1.u1
Investments
 3 Months Ended
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 CostAllowance for Expected Credit LossesGross UnrealizedFair Value
(at March 31, 2024, in millions)GainsLosses
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 obligation18,138 — 41 1,455 16,724 
Revenue9,419 — 27 700 8,746 
State general obligation1,156 — 3 67 1,092 
Pre-refunded952 — 2 4 950 
Total obligations of U.S. states, municipalities and political subdivisions29,665 — 73 2,226 27,512 
Debt securities issued by foreign governments970 — 1 32 939 
Mortgage-backed securities, collateralized mortgage obligations and pass-through securities
9,076 — 68 224 8,920 
Corporate and all other bonds36,512 3 103 2,232 34,380 
Total$82,712 $3 $246 $4,964 $77,991 
 Amortized CostAllowance for Expected Credit LossesGross UnrealizedFair Value
(at December 31, 2023, in millions)GainsLosses
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 obligation18,374 — 90 1,265 17,199 
Revenue9,748 — 52 616 9,184 
State general obligation1,209 — 7 59 1,157 
Pre-refunded963 — 5 2 966 
Total obligations of U.S. states, municipalities and political subdivisions30,294 — 154 1,942 28,506 
Debt securities issued by foreign governments1,035 — 2 31 1,006 
Mortgage-backed securities, collateralized mortgage obligations and pass-through securities
7,874 — 120 176 7,818 
Corporate and all other bonds35,987 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)CostGross GainsGross LossesFair Value
Common stock$512 $142 $13 $641 
Non-redeemable preferred stock45 3 — 48 
Total$557 $145 $13 $689 
(at December 31, 2023, in millions)CostGross GainsGross LossesFair Value
Common stock$508 $93 $41 $560 
Non-redeemable preferred stock45 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 months12 months or longerTotal
(at March 31, 2024, in millions)Fair
Value		Gross
Unrealized
Losses		Fair
Value		Gross
Unrealized
Losses		Fair
Value		Gross
Unrealized
Losses
Fixed maturities      
U.S. Treasury securities and obligations of U.S. government and government agencies and authorities
$2,866 $17 $2,869 $233 $5,735 $250 
Obligations of U.S. states, municipalities and political subdivisions6,958 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 bonds2,957 28 25,668 2,204 28,625 2,232 
Total $16,021 $142 $46,120 $4,822 $62,141 $4,964 
Less than 12 months12 months or longerTotal
(at December 31, 2023, in millions)Fair
Value		Gross
Unrealized
Losses		Fair
Value		Gross
Unrealized
Losses		Fair
Value		Gross
Unrealized
Losses
Fixed maturities  
U.S. Treasury securities and obligations of U.S. government and government agencies and authorities
$1,864 $7 $2,985  $224 $4,849 $231 
Obligations of U.S. states, municipalities and political subdivisions3,868 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 bonds1,016 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 lessGreater than 3 months, 6 months or lessGreater than 6 months, 12 months or lessGreater than 12 monthsTotal
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 subdivisions224 — 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 bonds41 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 lessGreater than 3 months, 6 months or lessGreater than 6 months, 12 months or lessGreater than 12 monthsTotal
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 bonds1 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 recognized3 — 
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.
v3.24.1.u1
Fair Value Measurements
 3 Months Ended
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)TotalLevel 1Level 2Level 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 subdivisions27,512 — 27,512 — 
Debt securities issued by foreign governments939 — 939 — 
Mortgage-backed securities, collateralized mortgage obligations and pass-through securities
8,920 — 8,899 21 
Corporate and all other bonds34,380 — 34,125 255 
Total fixed maturities77,991 6,240 71,475 276 
Equity securities    
Common stock641 634 — 7 
Non-redeemable preferred stock48 15 3 30 
Total equity securities689 649 3 37 
Other investments18 18 — — 
Total$78,698 $6,907 $71,478 $313 
(at December 31, 2023, in millions)TotalLevel 1Level 2Level 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 subdivisions28,506 — 28,506 — 
Debt securities issued by foreign governments1,006 — 1,006 — 
Mortgage-backed securities, collateralized mortgage obligations and pass-through securities
7,818 — 7,818 — 
Corporate and all other bonds34,109 — 33,851 258 
Total fixed maturities77,807 6,368 71,181 258 
Equity securities    
Common stock560 553 — 7 
Non-redeemable preferred stock48 16 2 30 
Total equity securities608 569 2 37 
Other investments18 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
Value		Fair
Value		Level 1Level 2Level 3
Financial assets     
Short-term securities$4,682 $4,682 $999 $3,634 $49 
Financial liabilities     
Debt$7,932 $7,406 $— $7,406 $— 
Commercial paper100 100 — 100 — 
(at December 31, 2023, in millions)Carrying
Value		Fair
Value		Level 1Level 2Level 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 paper100 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.
v3.24.1.u1
Allowance for Expected Credit Losses
 3 Months Ended
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, 2024At and For the Three Months Ended March 31, 2023
(in millions)Premiums Receivable, Net of Allowance for Expected Credit LossesAllowance for Expected Credit LossesPremiums Receivable, Net of Allowance for Expected Credit LossesAllowance for Expected Credit Losses
 
Balance, beginning of period$10,282 $69 $8,922 $77 
Current period change for expected credit losses12 10 
Write-offs of uncollectible premiums receivable13 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, 2024At and For the Three Months Ended March 31, 2023
(in millions)Reinsurance Recoverables, Net of Allowance for Estimated Uncollectible ReinsuranceAllowance for Estimated Uncollectible ReinsuranceReinsurance Recoverables, Net of Allowance for Estimated Uncollectible ReinsuranceAllowance 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, 2024At and For the Three Months Ended March 31, 2023
(in millions)Contractholder Receivables, Net of Allowance for Expected Credit LossesAllowance for Expected Credit LossesContractholder Receivables, Net of Allowance for Expected Credit LossesAllowance 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 
v3.24.1.u1
Goodwill and Other Intangible Assets
 3 Months Ended
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,
2024		December 31,
2023
Business Insurance$2,579 $2,585 
Bond & Specialty Insurance (1)
835 550 
Personal Insurance811 815 
Other26 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
Carrying
Amount		Accumulated
Amortization		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 amortization408 258 150 
Not subject to amortization226 — 226 
Total$634 $258 $376 
(at December 31, 2023, in millions)Gross
Carrying
Amount		Accumulated
Amortization		Net
Subject to amortization
Customer-related$100 $59 $41 
Contract-based (2)
204 194 10 
Total subject to amortization304 253 51 
Not subject to amortization226 — 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)AmountWeighted Average Amortization Period
Subject to amortization
Customer-related$87 14 years
Marketing-related18 7 years
Total$105 13 years
v3.24.1.u1
Insurance Claim Reserves
 3 Months Ended
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,
2024		December 31,
2023
Property-casualty$62,482 $61,621 
Accident and health5 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)20242023
Claims and claim adjustment expense reserves at beginning of year$61,621 $58,643 
Less reinsurance recoverables on unpaid losses7,817 7,790 
Net reserves at beginning of year53,804 50,853 
Estimated claims and claim adjustment expenses for claims arising in the current year6,679 6,025 
Estimated decrease in claims and claim adjustment expenses for
 claims arising in prior years
(49)(90)
Total increases6,630 5,935 
Claims and claim adjustment expense payments for claims arising in:  
Current year1,275 1,177 
Prior years4,435 4,382 
Total payments5,710 5,559 
Unrealized foreign exchange (gain) loss(61)28 
Net reserves at end of period54,663 51,257 
Plus reinsurance recoverables on unpaid losses7,819 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 $28 million, primarily driven by better than expected loss experience in the domestic operations’ homeowners and other product line for recent accident years.
v3.24.1.u1
Other Comprehensive Income (Loss) and Accumulated Other Comprehensive Income (Loss)
 3 Months Ended
Mar. 31, 2024
Other Comprehensive Income And Accumulated Other Comprehensive Income Disclosure [Abstract]  
Other Comprehensive Income (Loss) and Accumulated Other Comprehensive Income (Loss) OTHER COMPREHENSIVE INCOME (LOSS) AND ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)
The following table presents the changes in the Company’s accumulated other comprehensive income (loss) (AOCI) for the three months ended March 31, 2024.
 Changes in Net Unrealized Gains (Losses) on Investment Securities  
(in millions)Having No Credit
Losses Recognized in
the Consolidated
Statement of Income		Having Credit 
Losses Recognized 
in the Consolidated
Statement of 
Income		Net Benefit Plan Assets and
Obligations
Recognized in
Shareholders’ 
Equity		Net Unrealized
Foreign Currency
Translation		Total Accumulated
Other
Comprehensive
Income (Loss)
Balance, December 31, 2023$(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)$(5,131)
The following table presents the pre-tax components of the Company’s other comprehensive income (loss) and the related income tax expense (benefit).
 Three Months Ended
March 31,
(in millions)20242023
Changes in net unrealized losses on investment securities:  
Having no credit losses recognized in the consolidated statement of income$(752)$1,308 
Income tax expense (benefit)(158)278 
Net of taxes(594)1,030 
Having credit losses recognized in the consolidated statement of income2 — 
Income tax expense— — 
Net of taxes2 — 
Net changes in benefit plan assets and obligations(1)(3)
Income tax expense (benefit)— (1)
Net of taxes(1)(2)
Net changes in unrealized foreign currency translation(71)37 
Income tax expense (benefit)(4)6 
Net of taxes(67)31 
Total other comprehensive income (loss)(822)1,342 
Total income tax expense (benefit)(162)283 
Total other comprehensive income (loss), net of taxes$(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
March 31,
(in millions)20242023
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 taxes32 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 reclassifications39 8 
Total income tax benefit8 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.
v3.24.1.u1
Common Share Repurchases
 3 Months Ended
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.
v3.24.1.u1
Earnings per Share
 3 Months Ended
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
March 31,
(in millions, except per share amounts)20242023
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 outstanding229.0 231.7 
Diluted
Weighted average shares outstanding229.0 231.7 
Weighted average effects of dilutive securities — stock options and performance shares
3.0 2.7 
Total232.0 234.4 
Net Income per Common Share
Basic$4.87 $4.18 
Diluted$4.80 $4.13 
v3.24.1.u1
Share-Based Incentive Compensation
 3 Months Ended
Mar. 31, 2024
Share-Based Payment Arrangement [Abstract]  
Share-Based Incentive Compensation SHARE-BASED INCENTIVE COMPENSATION
The following information relates to fully vested stock option awards at March 31, 2024:
                                           Stock OptionsNumberWeighted
Average
Exercise
Price		Weighted
Average
Contractual
Life
Remaining		Aggregate
Intrinsic
Value
($ in millions)
Vested at end of period (1)
6,832,710 $146.39 6.0 years$572 
Exercisable at end of period5,162,950 $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.
v3.24.1.u1
Pension Plans, Retirement Benefits and Savings Plans
 3 Months Ended
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 PlansPostretirement Benefit Plans
(for the three months ended March 31, in millions)2024202320242023
Net Periodic Benefit Cost (Benefit):    
Service cost$29 $27 $— $— 
Non-service cost (benefit):    
Interest cost on benefit obligation43 44 1 1 
Expected return on plan assets(75)(78)— — 
Amortization of unrecognized:
Prior service benefit— — (1)(1)
Net actuarial (gain) loss 2 — (2)(2)
Total non-service cost (benefit)(30)(34)(2)(2)
Net periodic benefit cost (benefit)$(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 PlansPostretirement Benefit Plans
(for the three months ended March 31, in millions)2024202320242023
Service Cost:    
Claims and claim adjustment expenses$11 $11 $— $— 
General and administrative expenses18 16 — — 
Total service cost29 27 — — 
Non-Service Cost (Benefit):    
Claims and claim adjustment expenses(12)(14)(1)(1)
General and administrative expenses(18)(20)(1)(1)
Total non-service cost (benefit)(30)(34)(2)(2)
Net periodic benefit cost (benefit)$(1)$(7)$(2)$(2)
v3.24.1.u1
Leases
 3 Months Ended
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
March 31,
(in millions)20242023
Lease cost
Operating leases$19 $19 
Short-term leases (1)
1 1 
Lease expense20 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 rate2.91 %2.44 %
Weighted average remaining lease term4.1 years4.4 years
_________________________________________________________
(1)Leases with a term of twelve months or less are not recorded on the consolidated balance sheet.
(2)Sublease income consists of rent from third parties of office space and is recognized as part of other revenues in the consolidated statement of income.
v3.24.1.u1
Contingencies, Commitments and Guarantees
 3 Months Ended
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 $480 million at March 31, 2024, all of which is indemnified by a third party.  For more information regarding the Company’s guarantees, see note 17 of the notes to the consolidated financial statements in the Company’s 2023 Annual Report.
v3.24.1.u1
Pay vs Performance Disclosure - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2024
Mar. 31, 2023
Pay vs Performance Disclosure    
Net income $ 1,123 $ 975
v3.24.1.u1
Insider Trading Arrangements
 3 Months Ended
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
v3.24.1.u1
Basis of Presentation and Accounting Policies (Policies)
 3 Months Ended
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.
v3.24.1.u1
Segment Information (Tables)
 3 Months Ended
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
Insurance		Bond & Specialty
Insurance		Personal
Insurance		Total
Reportable
Segments
2024    
Premiums$5,160 $956 $4,010 $10,126 
Net investment income609 90 147 846 
Fee income101 — 8 109 
Other revenues77 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 income473 73 117 663 
Fee income99 — 7 106 
Other revenues47 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
March 31,
(in millions)20242023
Revenue reconciliation  
Earned premiums  
Business Insurance:  
Domestic:  
Workers’ compensation$880 $850 
Commercial automobile860 761 
Commercial property873 709 
General liability847 760 
Commercial multi-peril1,270 1,100 
Other17 18 
Total Domestic4,747 4,198 
International413 279 
Total Business Insurance5,160 4,477 
Bond & Specialty Insurance:  
Domestic:  
Fidelity and surety340 306 
General liability426 398 
Other56 54 
Total Domestic822 758 
International134 117 
Total Bond & Specialty Insurance956 875 
Personal Insurance:  
Domestic:  
Automobile1,874 1,624 
Homeowners and Other1,972 1,724 
Total Domestic3,846 3,348 
International164 154 
Total Personal Insurance4,010 3,502 
Total earned premiums10,126 8,854 
Net investment income846 663 
Fee income109 106 
Other revenues112 75 
Total segment revenues11,193 9,698 
Net realized investment gains35 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 income1,096 970 
Net realized investment gains27 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,
2024		December 31,
2023
Asset reconciliation  
Business Insurance$94,393 $93,565 
Bond & Specialty Insurance12,136 11,478 
Personal Insurance20,003 20,072 
Total assets by reportable segment126,532 125,115 
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.
v3.24.1.u1
Investments (Tables)
 3 Months Ended
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 CostAllowance for Expected Credit LossesGross UnrealizedFair Value
(at March 31, 2024, in millions)GainsLosses
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 obligation18,138 — 41 1,455 16,724 
Revenue9,419 — 27 700 8,746 
State general obligation1,156 — 3 67 1,092 
Pre-refunded952 — 2 4 950 
Total obligations of U.S. states, municipalities and political subdivisions29,665 — 73 2,226 27,512 
Debt securities issued by foreign governments970 — 1 32 939 
Mortgage-backed securities, collateralized mortgage obligations and pass-through securities
9,076 — 68 224 8,920 
Corporate and all other bonds36,512 3 103 2,232 34,380 
Total$82,712 $3 $246 $4,964 $77,991 
 Amortized CostAllowance for Expected Credit LossesGross UnrealizedFair Value
(at December 31, 2023, in millions)GainsLosses
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 obligation18,374 — 90 1,265 17,199 
Revenue9,748 — 52 616 9,184 
State general obligation1,209 — 7 59 1,157 
Pre-refunded963 — 5 2 966 
Total obligations of U.S. states, municipalities and political subdivisions30,294 — 154 1,942 28,506 
Debt securities issued by foreign governments1,035 — 2 31 1,006 
Mortgage-backed securities, collateralized mortgage obligations and pass-through securities
7,874 — 120 176 7,818 
Corporate and all other bonds35,987 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)CostGross GainsGross LossesFair Value
Common stock$512 $142 $13 $641 
Non-redeemable preferred stock45 3 — 48 
Total$557 $145 $13 $689 
(at December 31, 2023, in millions)CostGross GainsGross LossesFair Value
Common stock$508 $93 $41 $560 
Non-redeemable preferred stock45 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 months12 months or longerTotal
(at March 31, 2024, in millions)Fair
Value		Gross
Unrealized
Losses		Fair
Value		Gross
Unrealized
Losses		Fair
Value		Gross
Unrealized
Losses
Fixed maturities      
U.S. Treasury securities and obligations of U.S. government and government agencies and authorities
$2,866 $17 $2,869 $233 $5,735 $250 
Obligations of U.S. states, municipalities and political subdivisions6,958 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 bonds2,957 28 25,668 2,204 28,625 2,232 
Total $16,021 $142 $46,120 $4,822 $62,141 $4,964 
Less than 12 months12 months or longerTotal
(at December 31, 2023, in millions)Fair
Value		Gross
Unrealized
Losses		Fair
Value		Gross
Unrealized
Losses		Fair
Value		Gross
Unrealized
Losses
Fixed maturities  
U.S. Treasury securities and obligations of U.S. government and government agencies and authorities
$1,864 $7 $2,985  $224 $4,849 $231 
Obligations of U.S. states, municipalities and political subdivisions3,868 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 bonds1,016 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 lessGreater than 3 months, 6 months or lessGreater than 6 months, 12 months or lessGreater than 12 monthsTotal
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 subdivisions224 — 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 bonds41 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 lessGreater than 3 months, 6 months or lessGreater than 6 months, 12 months or lessGreater than 12 monthsTotal
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 bonds1 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 recognized3 — 
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 
v3.24.1.u1
Fair Value Measurements (Tables)
 3 Months Ended
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)TotalLevel 1Level 2Level 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 subdivisions27,512 — 27,512 — 
Debt securities issued by foreign governments939 — 939 — 
Mortgage-backed securities, collateralized mortgage obligations and pass-through securities
8,920 — 8,899 21 
Corporate and all other bonds34,380 — 34,125 255 
Total fixed maturities77,991 6,240 71,475 276 
Equity securities    
Common stock641 634 — 7 
Non-redeemable preferred stock48 15 3 30 
Total equity securities689 649 3 37 
Other investments18 18 — — 
Total$78,698 $6,907 $71,478 $313 
(at December 31, 2023, in millions)TotalLevel 1Level 2Level 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 subdivisions28,506 — 28,506 — 
Debt securities issued by foreign governments1,006 — 1,006 — 
Mortgage-backed securities, collateralized mortgage obligations and pass-through securities
7,818 — 7,818 — 
Corporate and all other bonds34,109 — 33,851 258 
Total fixed maturities77,807 6,368 71,181 258 
Equity securities    
Common stock560 553 — 7 
Non-redeemable preferred stock48 16 2 30 
Total equity securities608 569 2 37 
Other investments18 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
Value		Fair
Value		Level 1Level 2Level 3
Financial assets     
Short-term securities$4,682 $4,682 $999 $3,634 $49 
Financial liabilities     
Debt$7,932 $7,406 $— $7,406 $— 
Commercial paper100 100 — 100 — 
(at December 31, 2023, in millions)Carrying
Value		Fair
Value		Level 1Level 2Level 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 paper100 100 — 100 — 
v3.24.1.u1
Allowance for Expected Credit Losses (Tables)
 3 Months Ended
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, 2024At and For the Three Months Ended March 31, 2023
(in millions)Premiums Receivable, Net of Allowance for Expected Credit LossesAllowance for Expected Credit LossesPremiums Receivable, Net of Allowance for Expected Credit LossesAllowance for Expected Credit Losses
 
Balance, beginning of period$10,282 $69 $8,922 $77 
Current period change for expected credit losses12 10 
Write-offs of uncollectible premiums receivable13 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, 2024At and For the Three Months Ended March 31, 2023
(in millions)Reinsurance Recoverables, Net of Allowance for Estimated Uncollectible ReinsuranceAllowance for Estimated Uncollectible ReinsuranceReinsurance Recoverables, Net of Allowance for Estimated Uncollectible ReinsuranceAllowance 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, 2024At and For the Three Months Ended March 31, 2023
(in millions)Contractholder Receivables, Net of Allowance for Expected Credit LossesAllowance for Expected Credit LossesContractholder Receivables, Net of Allowance for Expected Credit LossesAllowance 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 
v3.24.1.u1
Goodwill and Other Intangible Assets (Tables)
 3 Months Ended
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,
2024		December 31,
2023
Business Insurance$2,579 $2,585 
Bond & Specialty Insurance (1)
835 550 
Personal Insurance811 815 
Other26 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
Carrying
Amount		Accumulated
Amortization		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 amortization408 258 150 
Not subject to amortization226 — 226 
Total$634 $258 $376 
(at December 31, 2023, in millions)Gross
Carrying
Amount		Accumulated
Amortization		Net
Subject to amortization
Customer-related$100 $59 $41 
Contract-based (2)
204 194 10 
Total subject to amortization304 253 51 
Not subject to amortization226 — 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
Carrying
Amount		Accumulated
Amortization		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 amortization408 258 150 
Not subject to amortization226 — 226 
Total$634 $258 $376 
(at December 31, 2023, in millions)Gross
Carrying
Amount		Accumulated
Amortization		Net
Subject to amortization
Customer-related$100 $59 $41 
Contract-based (2)
204 194 10 
Total subject to amortization304 253 51 
Not subject to amortization226 — 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)AmountWeighted Average Amortization Period
Subject to amortization
Customer-related$87 14 years
Marketing-related18 7 years
Total$105 13 years
v3.24.1.u1
Insurance Claim Reserves (Tables)
 3 Months Ended
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,
2024		December 31,
2023
Property-casualty$62,482 $61,621 
Accident and health5 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)20242023
Claims and claim adjustment expense reserves at beginning of year$61,621 $58,643 
Less reinsurance recoverables on unpaid losses7,817 7,790 
Net reserves at beginning of year53,804 50,853 
Estimated claims and claim adjustment expenses for claims arising in the current year6,679 6,025 
Estimated decrease in claims and claim adjustment expenses for
 claims arising in prior years
(49)(90)
Total increases6,630 5,935 
Claims and claim adjustment expense payments for claims arising in:  
Current year1,275 1,177 
Prior years4,435 4,382 
Total payments5,710 5,559 
Unrealized foreign exchange (gain) loss(61)28 
Net reserves at end of period54,663 51,257 
Plus reinsurance recoverables on unpaid losses7,819 7,801 
Claims and claim adjustment expense reserves at end of period$62,482 $59,058 
v3.24.1.u1
Other Comprehensive Income (Loss) and Accumulated Other Comprehensive Income (Loss) (Tables)
 3 Months Ended
Mar. 31, 2024
Other Comprehensive Income And Accumulated Other Comprehensive Income Disclosure [Abstract]  
Changes in accumulated other comprehensive income (loss) (AOCI) [Table Text Block]
The following table presents the changes in the Company’s accumulated other comprehensive income (loss) (AOCI) for the three months ended March 31, 2024.
 Changes in Net Unrealized Gains (Losses) on Investment Securities  
(in millions)Having No Credit
Losses Recognized in
the Consolidated
Statement of Income		Having Credit 
Losses Recognized 
in the Consolidated
Statement of 
Income		Net Benefit Plan Assets and
Obligations
Recognized in
Shareholders’ 
Equity		Net Unrealized
Foreign Currency
Translation		Total Accumulated
Other
Comprehensive
Income (Loss)
Balance, December 31, 2023$(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)$(5,131)
Pre-tax components of other comprehensive income (loss) and the related income tax expense (benefit) for each component [Table Text Block]
The following table presents the pre-tax components of the Company’s other comprehensive income (loss) and the related income tax expense (benefit).
 Three Months Ended
March 31,
(in millions)20242023
Changes in net unrealized losses on investment securities:  
Having no credit losses recognized in the consolidated statement of income$(752)$1,308 
Income tax expense (benefit)(158)278 
Net of taxes(594)1,030 
Having credit losses recognized in the consolidated statement of income2 — 
Income tax expense— — 
Net of taxes2 — 
Net changes in benefit plan assets and obligations(1)(3)
Income tax expense (benefit)— (1)
Net of taxes(1)(2)
Net changes in unrealized foreign currency translation(71)37 
Income tax expense (benefit)(4)6 
Net of taxes(67)31 
Total other comprehensive income (loss)(822)1,342 
Total income tax expense (benefit)(162)283 
Total other comprehensive income (loss), net of taxes$(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
March 31,
(in millions)20242023
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 taxes32 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 reclassifications39 8 
Total income tax benefit8 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.
v3.24.1.u1
Earnings per Share (Table)
 3 Months Ended
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
March 31,
(in millions, except per share amounts)20242023
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 outstanding229.0 231.7 
Diluted
Weighted average shares outstanding229.0 231.7 
Weighted average effects of dilutive securities — stock options and performance shares
3.0 2.7 
Total232.0 234.4 
Net Income per Common Share
Basic$4.87 $4.18 
Diluted$4.80 $4.13 
v3.24.1.u1
Share-Based Incentive Compensation (Table)
 3 Months Ended
Mar. 31, 2024
Share-Based Payment Arrangement [Abstract]  
Information for fully vested stock option awards [Table Text Block]
The following information relates to fully vested stock option awards at March 31, 2024:
                                           Stock OptionsNumberWeighted
Average
Exercise
Price		Weighted
Average
Contractual
Life
Remaining		Aggregate
Intrinsic
Value
($ in millions)
Vested at end of period (1)
6,832,710 $146.39 6.0 years$572 
Exercisable at end of period5,162,950 $132.57 5.1 years$504 
_________________________________________________________
(1)Represents awards for which the requisite service has been rendered, including those that are retirement eligible.
v3.24.1.u1
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 PlansPostretirement Benefit Plans
(for the three months ended March 31, in millions)2024202320242023
Net Periodic Benefit Cost (Benefit):    
Service cost$29 $27 $— $— 
Non-service cost (benefit):    
Interest cost on benefit obligation43 44 1 1 
Expected return on plan assets(75)(78)— — 
Amortization of unrecognized:
Prior service benefit— — (1)(1)
Net actuarial (gain) loss 2 — (2)(2)
Total non-service cost (benefit)(30)(34)(2)(2)
Net periodic benefit cost (benefit)$(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 PlansPostretirement Benefit Plans
(for the three months ended March 31, in millions)2024202320242023
Service Cost:    
Claims and claim adjustment expenses$11 $11 $— $— 
General and administrative expenses18 16 — — 
Total service cost29 27 — — 
Non-Service Cost (Benefit):    
Claims and claim adjustment expenses(12)(14)(1)(1)
General and administrative expenses(18)(20)(1)(1)
Total non-service cost (benefit)(30)(34)(2)(2)
Net periodic benefit cost (benefit)$(1)$(7)$(2)$(2)
v3.24.1.u1
Leases (Table)
 3 Months Ended
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
March 31,
(in millions)20242023
Lease cost
Operating leases$19 $19 
Short-term leases (1)
1 1 
Lease expense20 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 rate2.91 %2.44 %
Weighted average remaining lease term4.1 years4.4 years
_________________________________________________________
(1)Leases with a term of twelve months or less are not recorded on the consolidated balance sheet.
(2)Sublease income consists of rent from third parties of office space and is recognized as part of other revenues in the consolidated statement of income.
v3.24.1.u1
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
v3.24.1.u1
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
v3.24.1.u1
Segment Information (Details)
$ in Millions
 3 Months Ended
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
v3.24.1.u1
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
v3.24.1.u1
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  
v3.24.1.u1
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
v3.24.1.u1
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
v3.24.1.u1
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) 1.00% 1.00%
Credit losses on fixed maturities recognized in the consolidated statement of income, as a percentage of shareholders' equity on an after-tax basis (less than) 1.00% 1.00%
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
v3.24.1.u1
Investments (Details) - Other Investments
 3 Months Ended
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
v3.24.1.u1
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 99.00% 99.00%
v3.24.1.u1
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
v3.24.1.u1
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
v3.24.1.u1
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
v3.24.1.u1
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
v3.24.1.u1
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 87.00%
Reinsurance Recoverables [Member] | Reinsurer Group Not Rated by A.M. Best [Member]  
Reinsurance recoverables, credit quality indicator  
Concentration risk percentage 13.00%
Reinsurance Recoverables [Member] | Captive Insurance Companies [Member]  
Reinsurance recoverables, credit quality indicator  
Concentration risk percentage 6.00%
Reinsurance Recoverables [Member] | Voluntary Pools [Member]  
Reinsurance recoverables, credit quality indicator  
Concentration risk percentage 1.00%
Reinsurance Recoverables [Member] | Other Companies [Member]  
Reinsurance recoverables, credit quality indicator  
Concentration risk percentage 6.00%
Reinsurance Recoverables Rated by A.M. Best [Member] | Reinsurer Group Rated by A.M. Best [Member] | A.M. Best, A- Rating Or Better [Member]  
Reinsurance recoverables, credit quality indicator  
Concentration risk percentage 94.00%
v3.24.1.u1
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
v3.24.1.u1
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
v3.24.1.u1
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    
v3.24.1.u1
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  
v3.24.1.u1
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
v3.24.1.u1
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
v3.24.1.u1
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
v3.24.1.u1
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
v3.24.1.u1
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) 229.0 231.7
Weighted average effects of dilutive securities - stock options and performance shares (in shares) 3.0 2.7
Weighted average shares outstanding, diluted (in shares) 232.0 234.4
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
v3.24.1.u1
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  
v3.24.1.u1
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)
v3.24.1.u1
Leases (Details) - USD ($)
$ in Millions
 3 Months Ended
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
v3.24.1.u1
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
v3.24.1.u1
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