v3.26.1
Investments - Unrealized Loss Position (Details)
$ in Millions
Mar. 31, 2026
USD ($)
security
Dec. 31, 2025
USD ($)
security
Number of Securities    
Number of Securities, Less than 12 months | security 5,268 1,578
Number of Securities, Greater than 12 months | security 2,019 2,465
Number of Securities | security 7,287 4,043
Fair Value    
Fair Value, Less than 12 months $ 10,083 $ 2,856
Fair Value, Greater than 12 months 2,740 3,476
Fair Value 12,823 6,332
Debt Securities, Available-for-Sale, Unrealized Loss Position, Accumulated Loss [Abstract]    
Unrealized Losses, Less than 12 months 142 30
Unrealized Losses, Greater than 12 months 305 301
Unrealized Losses $ 447 $ 331
U.S. government securities    
Number of Securities    
Number of Securities, Less than 12 months | security 151 50
Number of Securities, Greater than 12 months | security 71 80
Number of Securities | security 222 130
Fair Value    
Fair Value, Less than 12 months $ 597 $ 156
Fair Value, Greater than 12 months 149 168
Fair Value 746 324
Debt Securities, Available-for-Sale, Unrealized Loss Position, Accumulated Loss [Abstract]    
Unrealized Losses, Less than 12 months 5 2
Unrealized Losses, Greater than 12 months 5 6
Unrealized Losses $ 10 $ 8
States, municipalities and political subdivisions    
Number of Securities    
Number of Securities, Less than 12 months | security 34 16
Number of Securities, Greater than 12 months | security 63 89
Number of Securities | security 97 105
Fair Value    
Fair Value, Less than 12 months $ 84 $ 28
Fair Value, Greater than 12 months 91 136
Fair Value 175 164
Debt Securities, Available-for-Sale, Unrealized Loss Position, Accumulated Loss [Abstract]    
Unrealized Losses, Less than 12 months 1 0
Unrealized Losses, Greater than 12 months 6 7
Unrealized Losses $ 7 $ 7
U.S. corporate securities    
Number of Securities    
Number of Securities, Less than 12 months | security 3,450 1,045
Number of Securities, Greater than 12 months | security 1,287 1,541
Number of Securities | security 4,737 2,586
Fair Value    
Fair Value, Less than 12 months $ 5,547 $ 1,634
Fair Value, Greater than 12 months 1,787 2,149
Fair Value 7,334 3,783
Debt Securities, Available-for-Sale, Unrealized Loss Position, Accumulated Loss [Abstract]    
Unrealized Losses, Less than 12 months 96 23
Unrealized Losses, Greater than 12 months 218 208
Unrealized Losses $ 314 $ 231
Foreign securities    
Number of Securities    
Number of Securities, Less than 12 months | security 602 180
Number of Securities, Greater than 12 months | security 220 303
Number of Securities | security 822 483
Fair Value    
Fair Value, Less than 12 months $ 1,136 $ 310
Fair Value, Greater than 12 months 300 449
Fair Value 1,436 759
Debt Securities, Available-for-Sale, Unrealized Loss Position, Accumulated Loss [Abstract]    
Unrealized Losses, Less than 12 months 22 2
Unrealized Losses, Greater than 12 months 28 29
Unrealized Losses $ 50 $ 31
Residential mortgage-backed securities    
Number of Securities    
Number of Securities, Less than 12 months | security 150 67
Number of Securities, Greater than 12 months | security 281 303
Number of Securities | security 431 370
Fair Value    
Fair Value, Less than 12 months $ 303 $ 124
Fair Value, Greater than 12 months 223 272
Fair Value 526 396
Debt Securities, Available-for-Sale, Unrealized Loss Position, Accumulated Loss [Abstract]    
Unrealized Losses, Less than 12 months 3 1
Unrealized Losses, Greater than 12 months 28 28
Unrealized Losses $ 31 $ 29
Commercial mortgage-backed securities    
Number of Securities    
Number of Securities, Less than 12 months | security 220 84
Number of Securities, Greater than 12 months | security 76 126
Number of Securities | security 296 210
Fair Value    
Fair Value, Less than 12 months $ 750 $ 290
Fair Value, Greater than 12 months 163 269
Fair Value 913 559
Debt Securities, Available-for-Sale, Unrealized Loss Position, Accumulated Loss [Abstract]    
Unrealized Losses, Less than 12 months 9 1
Unrealized Losses, Greater than 12 months 19 22
Unrealized Losses $ 28 $ 23
Other asset-backed securities    
Number of Securities    
Number of Securities, Less than 12 months | security 657 136
Number of Securities, Greater than 12 months | security 21 19
Number of Securities | security 678 155
Fair Value    
Fair Value, Less than 12 months $ 1,660 $ 314
Fair Value, Greater than 12 months 27 27
Fair Value 1,687 341
Debt Securities, Available-for-Sale, Unrealized Loss Position, Accumulated Loss [Abstract]    
Unrealized Losses, Less than 12 months 6 1
Unrealized Losses, Greater than 12 months 1 1
Unrealized Losses $ 7 $ 2
Redeemable preferred securities    
Number of Securities    
Number of Securities, Less than 12 months | security 4 0
Number of Securities, Greater than 12 months | security 0 4
Number of Securities | security 4 4
Fair Value    
Fair Value, Less than 12 months $ 6 $ 0
Fair Value, Greater than 12 months 0 6
Fair Value 6 6
Debt Securities, Available-for-Sale, Unrealized Loss Position, Accumulated Loss [Abstract]    
Unrealized Losses, Less than 12 months 0 0
Unrealized Losses, Greater than 12 months 0 0
Unrealized Losses $ 0 $ 0