v3.26.1
Fair Value - Fair Value Hierarchy (Details) - USD ($)
$ in Millions
Jun. 30, 2026
Dec. 31, 2025
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Debt securities available for sale, at fair value $ 36,453 $ 35,051
Equity securities, at fair value 2,280 1,864
Derivative assets, at fair value 227 180
Other assets, at fair value 6,878 6,796
Other investments, at fair value 3,381 3,136
Other liabilities, at fair value (3,715) (3,517)
Liability derivatives - fair value (108) (72)
Corporate bonds    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Debt securities available for sale, at fair value 14,231 14,058
U.S. government and government agencies    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Debt securities available for sale, at fair value 8,060 7,445
Asset backed securities    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Debt securities available for sale, at fair value 3,677 3,574
Non-U.S. government securities    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Debt securities available for sale, at fair value 2,876 3,270
Residential mortgage backed securities    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Debt securities available for sale, at fair value 2,643 2,705
Commercial mortgage backed securities    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Debt securities available for sale, at fair value 1,549 1,212
Municipal bonds    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Debt securities available for sale, at fair value 119 162
Short term investments    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Other investments, at fair value 57 64
Other investments fair value option    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Other investments, at fair value 2,144 1,957
Equity securities    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Other investments, at fair value 5 5
Quoted Prices in Active Markets for Identical Assets (Level 1)    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Equity securities, at fair value 2,256 1,829
Derivative assets, at fair value 0 0
Other investments, at fair value 4 7
Total assets measured at fair value 13,194 11,607
Other liabilities, at fair value 0 0
Liability derivatives - fair value 0 0
Total liabilities measured at fair value 0 0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Corporate bonds    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Other investments, at fair value 0 0
Quoted Prices in Active Markets for Identical Assets (Level 1) | U.S. government and government agencies    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Other investments, at fair value 4 5
Quoted Prices in Active Markets for Identical Assets (Level 1) | Asset backed securities    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Other investments, at fair value   0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Non-U.S. government securities    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Other investments, at fair value 0 0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Short term investments    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Other investments, at fair value 0 2
Quoted Prices in Active Markets for Identical Assets (Level 1) | Residential mortgage loans    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Other assets, at fair value 0 0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Other investments fair value option    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Other investments, at fair value 0 0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Equity securities    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Other investments, at fair value 0 0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fixed maturities    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Debt securities available for sale, at fair value 8,060 7,445
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fixed maturities | Corporate bonds    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Debt securities available for sale, at fair value 0 0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fixed maturities | U.S. government and government agencies    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Debt securities available for sale, at fair value 8,060 7,445
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fixed maturities | Asset backed securities    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Debt securities available for sale, at fair value 0 0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fixed maturities | Non-U.S. government securities    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Debt securities available for sale, at fair value 0 0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fixed maturities | Residential mortgage backed securities    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Debt securities available for sale, at fair value 0 0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fixed maturities | Commercial mortgage backed securities    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Debt securities available for sale, at fair value 0 0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fixed maturities | Municipal bonds    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Debt securities available for sale, at fair value 0 0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Short-term investments    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Debt securities available for sale, at fair value 2,874 2,326
Significant Other Observable Inputs (Level 2)    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Equity securities, at fair value 14 26
Derivative assets, at fair value 227 180
Other investments, at fair value 1,341 1,293
Total assets measured at fair value 27,011 26,658
Other liabilities, at fair value 0 0
Liability derivatives - fair value (108) (72)
Total liabilities measured at fair value (108) (72)
Significant Other Observable Inputs (Level 2) | Corporate bonds    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Other investments, at fair value 1,168 1,102
Significant Other Observable Inputs (Level 2) | U.S. government and government agencies    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Other investments, at fair value 0 0
Significant Other Observable Inputs (Level 2) | Asset backed securities    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Other investments, at fair value   0
Significant Other Observable Inputs (Level 2) | Non-U.S. government securities    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Other investments, at fair value 3 3
Significant Other Observable Inputs (Level 2) | Short term investments    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Other investments, at fair value 13 22
Significant Other Observable Inputs (Level 2) | Residential mortgage loans    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Other assets, at fair value 54 24
Significant Other Observable Inputs (Level 2) | Other investments fair value option    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Other investments, at fair value 157 166
Significant Other Observable Inputs (Level 2) | Equity securities    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Other investments, at fair value 0 0
Significant Other Observable Inputs (Level 2) | Fixed maturities    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Debt securities available for sale, at fair value 24,951 24,836
Significant Other Observable Inputs (Level 2) | Fixed maturities | Corporate bonds    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Debt securities available for sale, at fair value 14,117 13,930
Significant Other Observable Inputs (Level 2) | Fixed maturities | U.S. government and government agencies    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Debt securities available for sale, at fair value 0 0
Significant Other Observable Inputs (Level 2) | Fixed maturities | Asset backed securities    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Debt securities available for sale, at fair value 3,651 3,557
Significant Other Observable Inputs (Level 2) | Fixed maturities | Non-U.S. government securities    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Debt securities available for sale, at fair value 2,876 3,270
Significant Other Observable Inputs (Level 2) | Fixed maturities | Residential mortgage backed securities    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Debt securities available for sale, at fair value 2,639 2,705
Significant Other Observable Inputs (Level 2) | Fixed maturities | Commercial mortgage backed securities    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Debt securities available for sale, at fair value 1,549 1,212
Significant Other Observable Inputs (Level 2) | Fixed maturities | Municipal bonds    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Debt securities available for sale, at fair value 119 162
Significant Other Observable Inputs (Level 2) | Short-term investments    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Debt securities available for sale, at fair value 424 299
Significant Unobservable Inputs (Level 3)    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Equity securities, at fair value 10 9
Derivative assets, at fair value 0 0
Other investments, at fair value 320 277
Total assets measured at fair value 474 431
Other liabilities, at fair value (14) (18)
Liability derivatives - fair value 0 0
Total liabilities measured at fair value (14) (18)
Significant Unobservable Inputs (Level 3) | Corporate bonds    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Other investments, at fair value 0 0
Significant Unobservable Inputs (Level 3) | U.S. government and government agencies    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Other investments, at fair value 0 0
Significant Unobservable Inputs (Level 3) | Asset backed securities    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Other investments, at fair value   0
Significant Unobservable Inputs (Level 3) | Non-U.S. government securities    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Other investments, at fair value 0 0
Significant Unobservable Inputs (Level 3) | Short term investments    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Other investments, at fair value 44 40
Significant Unobservable Inputs (Level 3) | Residential mortgage loans    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Other assets, at fair value 0 0
Significant Unobservable Inputs (Level 3) | Other investments fair value option    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Other investments, at fair value 272 232
Significant Unobservable Inputs (Level 3) | Equity securities    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Other investments, at fair value 4 5
Significant Unobservable Inputs (Level 3) | Fixed maturities    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Debt securities available for sale, at fair value 144 145
Significant Unobservable Inputs (Level 3) | Fixed maturities | Corporate bonds    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Debt securities available for sale, at fair value 114 128
Significant Unobservable Inputs (Level 3) | Fixed maturities | U.S. government and government agencies    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Debt securities available for sale, at fair value 0 0
Significant Unobservable Inputs (Level 3) | Fixed maturities | Asset backed securities    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Debt securities available for sale, at fair value 26 17
Significant Unobservable Inputs (Level 3) | Fixed maturities | Non-U.S. government securities    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Debt securities available for sale, at fair value 0 0
Significant Unobservable Inputs (Level 3) | Fixed maturities | Residential mortgage backed securities    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Debt securities available for sale, at fair value 4 0
Significant Unobservable Inputs (Level 3) | Fixed maturities | Commercial mortgage backed securities    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Debt securities available for sale, at fair value 0 0
Significant Unobservable Inputs (Level 3) | Fixed maturities | Municipal bonds    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Debt securities available for sale, at fair value 0 0
Significant Unobservable Inputs (Level 3) | Short-term investments    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Debt securities available for sale, at fair value 0 0
Estimated Fair Value    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Equity securities, at fair value 2,280 1,864
Derivative assets, at fair value 227 180
Other investments, at fair value 3,380 3,136
Total assets measured at fair value 42,394 40,255
Other liabilities, at fair value (14) (18)
Liability derivatives - fair value (108) (72)
Total liabilities measured at fair value (122) (90)
Estimated Fair Value | Corporate bonds    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Other investments, at fair value 1,168 1,102
Estimated Fair Value | U.S. government and government agencies    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Other investments, at fair value 4 5
Estimated Fair Value | Asset backed securities    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Other investments, at fair value   0
Estimated Fair Value | Non-U.S. government securities    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Other investments, at fair value 3 3
Estimated Fair Value | Short term investments    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Other investments, at fair value 57 64
Estimated Fair Value | Residential mortgage loans    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Other assets, at fair value 54 24
Estimated Fair Value | Other investments fair value option    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Other investments, at fair value 429 398
Estimated Fair Value | Equity securities    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Other investments, at fair value 4 5
Estimated Fair Value | Fixed maturities    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Debt securities available for sale, at fair value 33,155 32,426
Estimated Fair Value | Fixed maturities | Corporate bonds    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Debt securities available for sale, at fair value 14,231 14,058
Estimated Fair Value | Fixed maturities | U.S. government and government agencies    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Debt securities available for sale, at fair value 8,060 7,445
Estimated Fair Value | Fixed maturities | Asset backed securities    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Debt securities available for sale, at fair value 3,677 3,574
Estimated Fair Value | Fixed maturities | Non-U.S. government securities    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Debt securities available for sale, at fair value 2,876 3,270
Estimated Fair Value | Fixed maturities | Residential mortgage backed securities    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Debt securities available for sale, at fair value 2,643 2,705
Estimated Fair Value | Fixed maturities | Commercial mortgage backed securities    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Debt securities available for sale, at fair value 1,549 1,212
Estimated Fair Value | Fixed maturities | Municipal bonds    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Debt securities available for sale, at fair value 119 162
Estimated Fair Value | Short-term investments    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Debt securities available for sale, at fair value 3,298 2,625
Estimated Fair Value | Other investments measured at net asset value    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Other investments, at fair value [1] $ 1,715 $ 1,559
[1] In accordance with applicable accounting guidance, certain investments that are measured at fair value using the net asset value per share (or its equivalent) practical expedient have not been classified in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the consolidated balance sheets.