v3.26.1
Investments (Securities in a gross unrealized loss position) (Details) - USD ($)
$ in Millions
Mar. 31, 2026
Dec. 31, 2025
Debt Securities, Available-for-sale [Line Items]    
Estimated Fair Value, Less than 12 months $ 9,109 $ 3,998
Gross Unrealized Losses, Less than 12 Months 182 79
Estimated Fair Value, 12 Months or Longer 15,592 16,646
Gross Unrealized Losses, 12 Months or Longer 2,386 2,207
Estimated Fair Value, Total 24,701 20,644
Gross Unrealized Losses, Total 2,568 2,286
Corporate and other bonds    
Debt Securities, Available-for-sale [Line Items]    
Estimated Fair Value, Less than 12 months 6,698 2,776
Gross Unrealized Losses, Less than 12 Months 142 56
Estimated Fair Value, 12 Months or Longer 7,903 8,576
Gross Unrealized Losses, 12 Months or Longer 932 825
Estimated Fair Value, Total 14,601 11,352
Gross Unrealized Losses, Total 1,074 881
States, municipalities and political subdivisions    
Debt Securities, Available-for-sale [Line Items]    
Estimated Fair Value, Less than 12 months 718 403
Gross Unrealized Losses, Less than 12 Months 12 8
Estimated Fair Value, 12 Months or Longer 3,398 3,471
Gross Unrealized Losses, 12 Months or Longer 781 734
Estimated Fair Value, Total 4,116 3,874
Gross Unrealized Losses, Total 793 742
Residential mortgage-backed    
Debt Securities, Available-for-sale [Line Items]    
Estimated Fair Value, Less than 12 months 365 154
Gross Unrealized Losses, Less than 12 Months 5 1
Estimated Fair Value, 12 Months or Longer 1,882 2,002
Gross Unrealized Losses, 12 Months or Longer 367 365
Estimated Fair Value, Total 2,247 2,156
Gross Unrealized Losses, Total 372 366
Commercial mortgage-backed    
Debt Securities, Available-for-sale [Line Items]    
Estimated Fair Value, Less than 12 months 126 36
Gross Unrealized Losses, Less than 12 Months 3 2
Estimated Fair Value, 12 Months or Longer 825 887
Gross Unrealized Losses, 12 Months or Longer 78 78
Estimated Fair Value, Total 951 923
Gross Unrealized Losses, Total 81 80
Other asset-backed    
Debt Securities, Available-for-sale [Line Items]    
Estimated Fair Value, Less than 12 months 819 420
Gross Unrealized Losses, Less than 12 Months 13 9
Estimated Fair Value, 12 Months or Longer 1,334 1,432
Gross Unrealized Losses, 12 Months or Longer 206 185
Estimated Fair Value, Total 2,153 1,852
Gross Unrealized Losses, Total 219 194
Asset-backed    
Debt Securities, Available-for-sale [Line Items]    
Estimated Fair Value, Less than 12 months 1,310 610
Gross Unrealized Losses, Less than 12 Months 21 12
Estimated Fair Value, 12 Months or Longer 4,041 4,321
Gross Unrealized Losses, 12 Months or Longer 651 628
Estimated Fair Value, Total 5,351 4,931
Gross Unrealized Losses, Total 672 640
U.S. Treasury and obligations of government-sponsored enterprises    
Debt Securities, Available-for-sale [Line Items]    
Estimated Fair Value, Less than 12 months 98 78
Gross Unrealized Losses, Less than 12 Months 2 2
Estimated Fair Value, 12 Months or Longer 14 18
Gross Unrealized Losses, 12 Months or Longer 1 1
Estimated Fair Value, Total 112 96
Gross Unrealized Losses, Total 3 3
Foreign government    
Debt Securities, Available-for-sale [Line Items]    
Estimated Fair Value, Less than 12 months 285 131
Gross Unrealized Losses, Less than 12 Months 5 1
Estimated Fair Value, 12 Months or Longer 236 260
Gross Unrealized Losses, 12 Months or Longer 21 19
Estimated Fair Value, Total 521 391
Gross Unrealized Losses, Total $ 26 $ 20