v3.25.1
Investments (Securities in a gross unrealized loss position) (Details) - USD ($)
$ in Millions
Mar. 31, 2025
Dec. 31, 2024
Debt Securities, Available-for-sale [Line Items]    
Estimated Fair Value, Less than 12 months $ 8,048 $ 9,019
Gross Unrealized Losses, Less than 12 Months 221 267
Estimated Fair Value, 12 Months or Longer 17,798 18,319
Gross Unrealized Losses, 12 Months or Longer 2,546 2,773
Estimated Fair Value, Total 25,846 27,338
Gross Unrealized Losses, Total 2,767 3,040
Corporate and other bonds    
Debt Securities, Available-for-sale [Line Items]    
Estimated Fair Value, Less than 12 months 5,816 5,846
Gross Unrealized Losses, Less than 12 Months 141 165
Estimated Fair Value, 12 Months or Longer 9,986 10,388
Gross Unrealized Losses, 12 Months or Longer 1,008 1,140
Estimated Fair Value, Total 15,802 16,234
Gross Unrealized Losses, Total 1,149 1,305
States, municipalities and political subdivisions    
Debt Securities, Available-for-sale [Line Items]    
Estimated Fair Value, Less than 12 months 944 1,247
Gross Unrealized Losses, Less than 12 Months 51 52
Estimated Fair Value, 12 Months or Longer 2,986 2,967
Gross Unrealized Losses, 12 Months or Longer 778 783
Estimated Fair Value, Total 3,930 4,214
Gross Unrealized Losses, Total 829 835
Residential mortgage-backed    
Debt Securities, Available-for-sale [Line Items]    
Estimated Fair Value, Less than 12 months 413 849
Gross Unrealized Losses, Less than 12 Months 9 22
Estimated Fair Value, 12 Months or Longer 2,016 2,010
Gross Unrealized Losses, 12 Months or Longer 417 466
Estimated Fair Value, Total 2,429 2,859
Gross Unrealized Losses, Total 426 488
Commercial mortgage-backed    
Debt Securities, Available-for-sale [Line Items]    
Estimated Fair Value, Less than 12 months 98 230
Gross Unrealized Losses, Less than 12 Months 1 3
Estimated Fair Value, 12 Months or Longer 969 988
Gross Unrealized Losses, 12 Months or Longer 118 139
Estimated Fair Value, Total 1,067 1,218
Gross Unrealized Losses, Total 119 142
Other asset-backed    
Debt Securities, Available-for-sale [Line Items]    
Estimated Fair Value, Less than 12 months 629 680
Gross Unrealized Losses, Less than 12 Months 16 21
Estimated Fair Value, 12 Months or Longer 1,499 1,557
Gross Unrealized Losses, 12 Months or Longer 200 218
Estimated Fair Value, Total 2,128 2,237
Gross Unrealized Losses, Total 216 239
Asset-backed    
Debt Securities, Available-for-sale [Line Items]    
Estimated Fair Value, Less than 12 months 1,140 1,759
Gross Unrealized Losses, Less than 12 Months 26 46
Estimated Fair Value, 12 Months or Longer 4,484 4,555
Gross Unrealized Losses, 12 Months or Longer 735 823
Estimated Fair Value, Total 5,624 6,314
Gross Unrealized Losses, Total 761 869
U.S. Treasury and obligations of government-sponsored enterprises    
Debt Securities, Available-for-sale [Line Items]    
Estimated Fair Value, Less than 12 months 43 49
Gross Unrealized Losses, Less than 12 Months 1 1
Estimated Fair Value, 12 Months or Longer 42 41
Gross Unrealized Losses, 12 Months or Longer 1 0
Estimated Fair Value, Total 85 90
Gross Unrealized Losses, Total 2 1
Foreign government    
Debt Securities, Available-for-sale [Line Items]    
Estimated Fair Value, Less than 12 months 105 118
Gross Unrealized Losses, Less than 12 Months 2 3
Estimated Fair Value, 12 Months or Longer 300 368
Gross Unrealized Losses, 12 Months or Longer 24 27
Estimated Fair Value, Total 405 486
Gross Unrealized Losses, Total $ 26 $ 30