v3.26.1
Fair value measurements (Financial Instruments Measured At Fair Value On Recurring Basis) (Details) - USD ($)
$ in Millions
Jun. 30, 2026
Dec. 31, 2025
Jun. 30, 2025
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]      
Debt Securities, Available-for-Sale $ 125,518 $ 122,680  
Equity securities 11,014 10,801  
Short-term investments 5,458 4,840  
Other investments 11,022 10,749  
Securities lending collateral 1,870 2,500  
Separate account assets 7,471 6,925 $ 6,481
Market risk benefits 505 659  
Private equities 17,385 17,239  
Reserved alternative investment fund      
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]      
Equity securities 5,510 5,519  
Other Investments      
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]      
Other investments 1,851 1,435  
Investment Funds Limited Partnerships Partially Owned Investment Companies Fair Value      
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]      
Private equities 17,385 17,239  
U.S. and local government securities      
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]      
Debt Securities, Available-for-Sale 3,594 3,714  
Non-U.S.      
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]      
Debt Securities, Available-for-Sale 41,372 40,356  
Corporate and asset-backed securities      
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]      
Debt Securities, Available-for-Sale 47,927 47,886  
Mortgage-backed securities      
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]      
Debt Securities, Available-for-Sale 32,625 30,724  
Level 1 | Fair Value, Recurring      
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]      
Debt Securities, Available-for-Sale 1,442 1,481  
Equity securities 5,394 [1] 5,163 [2]  
Short-term investments 3,074 2,657  
Other investments 716 [3] 630 [4]  
Securities lending collateral 0 0  
Investment derivatives 34 22  
Derivatives designated as hedging instruments 0 0  
Other derivative instruments 15 11  
Separate account assets 7,405 6,858  
Total assets measured at fair value 18,080 [1],[3],[5] 16,822 [2],[4],[6]  
Investment derivatives 371 242  
Derivatives designated as hedging instruments 0 0  
Other derivative instruments, liability 2    
Market risk benefits 0 [7] 0 [8]  
Total liabilities measured at fair value 373 242  
Level 1 | U.S. and local government securities | Fair Value, Recurring      
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]      
Debt Securities, Available-for-Sale 1,442 1,481  
Level 1 | Non-U.S. | Fair Value, Recurring      
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]      
Debt Securities, Available-for-Sale 0 0  
Level 1 | Corporate and asset-backed securities | Fair Value, Recurring      
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]      
Debt Securities, Available-for-Sale 0 0  
Level 1 | Mortgage-backed securities | Fair Value, Recurring      
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]      
Debt Securities, Available-for-Sale 0 0  
Level 2 | Fair Value, Recurring      
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]      
Debt Securities, Available-for-Sale 119,840 116,982  
Equity securities 0 [1] 0 [2]  
Short-term investments 2,374 2,138  
Other investments 8,455 [3] 8,684 [4]  
Securities lending collateral 1,870 2,500  
Investment derivatives 0 0  
Derivatives designated as hedging instruments 346 266  
Other derivative instruments 0 0  
Separate account assets 66 67  
Total assets measured at fair value 132,951 [1],[3],[5] 130,637 [2],[4],[6]  
Investment derivatives 0 0  
Derivatives designated as hedging instruments 127 232  
Other derivative instruments, liability 0 4  
Market risk benefits 0 [7] 0 [8]  
Total liabilities measured at fair value 127 236  
Level 2 | U.S. and local government securities | Fair Value, Recurring      
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]      
Debt Securities, Available-for-Sale 2,152 2,233  
Level 2 | Non-U.S. | Fair Value, Recurring      
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]      
Debt Securities, Available-for-Sale 40,678 39,685  
Level 2 | Corporate and asset-backed securities | Fair Value, Recurring      
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]      
Debt Securities, Available-for-Sale 44,385 44,340  
Level 2 | Mortgage-backed securities | Fair Value, Recurring      
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]      
Debt Securities, Available-for-Sale 32,625 30,724  
Level 3 | Fair Value, Recurring      
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]      
Debt Securities, Available-for-Sale 4,236 4,217  
Equity securities 110 [1] 119 [2]  
Short-term investments 10 45  
Other investments 0 [3] 0 [4]  
Securities lending collateral 0 0  
Investment derivatives 0 0  
Derivatives designated as hedging instruments 0 0  
Other derivative instruments 0 0  
Separate account assets 0 0  
Total assets measured at fair value 4,356 [1],[3],[5] 4,381 [2],[4],[6]  
Investment derivatives 0 0  
Derivatives designated as hedging instruments 0 0  
Other derivative instruments, liability 0 0  
Market risk benefits 505 [7] 659 [8]  
Total liabilities measured at fair value 505 659  
Level 3 | U.S. and local government securities | Fair Value, Recurring      
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]      
Debt Securities, Available-for-Sale 0 0  
Level 3 | Non-U.S. | Fair Value, Recurring      
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]      
Debt Securities, Available-for-Sale 694 671  
Level 3 | Corporate and asset-backed securities | Fair Value, Recurring      
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]      
Debt Securities, Available-for-Sale 3,542 3,546  
Level 3 | Mortgage-backed securities | Fair Value, Recurring      
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]      
Debt Securities, Available-for-Sale 0 0  
Total Level 1, Level 2, and Level 3 | Fair Value, Recurring      
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]      
Debt Securities, Available-for-Sale 125,518 122,680  
Equity securities 5,504 [1] 5,282 [2]  
Short-term investments 5,458 4,840  
Other investments 9,171 [3] 9,314 [4]  
Securities lending collateral 1,870 2,500  
Investment derivatives 34 22  
Derivatives designated as hedging instruments 346 266  
Other derivative instruments 15 11  
Separate account assets 7,471 6,925  
Total assets measured at fair value 155,387 [1],[3],[5] 151,840 [2],[4],[6]  
Investment derivatives 371 242  
Derivatives designated as hedging instruments 127 232  
Other derivative instruments, liability 2 4  
Market risk benefits 505 [7] 659 [8]  
Total liabilities measured at fair value 1,005 1,137  
Total Level 1, Level 2, and Level 3 | U.S. and local government securities | Fair Value, Recurring      
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]      
Debt Securities, Available-for-Sale 3,594 3,714  
Total Level 1, Level 2, and Level 3 | Non-U.S. | Fair Value, Recurring      
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]      
Debt Securities, Available-for-Sale 41,372 40,356  
Total Level 1, Level 2, and Level 3 | Corporate and asset-backed securities | Fair Value, Recurring      
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]      
Debt Securities, Available-for-Sale 47,927 47,886  
Total Level 1, Level 2, and Level 3 | Mortgage-backed securities | Fair Value, Recurring      
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]      
Debt Securities, Available-for-Sale $ 32,625 $ 30,724  
[1] Excluded from the table above are funds of $5,510 million, measured using NAV as a practical expedient.
[2] Excluded from the table above are funds of $5,519 million, measured using NAV as a practical expedient.
[3] Excluded from the table above are other investments of $1,851 million, principally investments measured using NAV as a practical expedient and policy loans.
[4] Excluded from the table above are other investments of $1,435 million, principally investments measured using NAV as a practical expedient and policy loans.
[5] Excluded from the table above are private equities of $17,385 million, measured using NAV as a practical expedient.
[6] Excluded from the table above are private equities of $17,239 million, measured using NAV as a practical expedient.
[7] Refer to Note 10 for additional information on Market risk benefits.
[8] Refer to Note 10 for additional information on Market risk benefits.