|**Investments (Summary of fixed maturity and equity securities) (Details) - USD ($) $ in Millions**                                                                                                                                                                                                                                                                                                                                                                                    | Dec. 31, 2023                                                                                                                                                                                                                                                                                                                                                                                                                                                                      | Dec. 31, 2022                                                                                                                                                                                                                                                                                                                                                                                                                                                                      | Dec. 31, 2021
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | -------------
|**Fixed maturity securities available-for-sale:**                                                                                                                                                                                                                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |              
|Cost or Amortized Cost                                                                                                                                                                                                                                                                                                                                                                                                                                                                 | $ 42,414                                                                                                                                                                                                                                                                                                                                                                                                                                                                           | $ 41,032                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |              
|Gross Unrealized Gains                                                                                                                                                                                                                                                                                                                                                                                                                                                                 | 1,022                                                                                                                                                                                                                                                                                                                                                                                                                                                                              | 652                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |              
|Gross Unrealized Losses                                                                                                                                                                                                                                                                                                                                                                                                                                                                | 2,995                                                                                                                                                                                                                                                                                                                                                                                                                                                                              | 4,056                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |              
|Allowance for Credit Losses                                                                                                                                                                                                                                                                                                                                                                                                                                                            | 16                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 | 1                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |              
|Estimated Fair Value                                                                                                                                                                                                                                                                                                                                                                                                                                                                   | 40,425                                                                                                                                                                                                                                                                                                                                                                                                                                                                             | 37,627                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |              
|**Debt Securities, Trading, Unrealized Gain (Loss) [Abstract]**                                                                                                                                                                                                                                                                                                                                                                                                                        |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |              
|Total fixed maturity securities trading                                                                                                                                                                                                                                                                                                                                                                                                                                                | 0                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | 0                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |              
|Total fixed maturity securities trading                                                                                                                                                                                                                                                                                                                                                                                                                                                | 0                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | 0                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |              
|Debt securities, amortized cost                                                                                                                                                                                                                                                                                                                                                                                                                                                        | 42,414                                                                                                                                                                                                                                                                                                                                                                                                                                                                             | 41,032                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |              
|Total fixed maturity securities                                                                                                                                                                                                                                                                                                                                                                                                                                                        | 40,425                                                                                                                                                                                                                                                                                                                                                                                                                                                                             | 37,627                                                                                                                                                                                                                                                                                                                                                                                                                                                                             | [1]          
|Corporate and other bonds                                                                                                                                                                                                                                                                                                                                                                                                                                                              |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |              
|**Fixed maturity securities available-for-sale:**                                                                                                                                                                                                                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |              
|Cost or Amortized Cost                                                                                                                                                                                                                                                                                                                                                                                                                                                                 | 25,020                                                                                                                                                                                                                                                                                                                                                                                                                                                                             | 23,137                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |              
|Gross Unrealized Gains                                                                                                                                                                                                                                                                                                                                                                                                                                                                 | 597                                                                                                                                                                                                                                                                                                                                                                                                                                                                                | 301                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |              
|Gross Unrealized Losses                                                                                                                                                                                                                                                                                                                                                                                                                                                                | 1,345                                                                                                                                                                                                                                                                                                                                                                                                                                                                              | 2,009                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |              
|Allowance for Credit Losses                                                                                                                                                                                                                                                                                                                                                                                                                                                            | 4                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | 0                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |              
|Estimated Fair Value                                                                                                                                                                                                                                                                                                                                                                                                                                                                   | 24,268                                                                                                                                                                                                                                                                                                                                                                                                                                                                             | 21,429                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |              
|**Debt Securities, Trading, Unrealized Gain (Loss) [Abstract]**                                                                                                                                                                                                                                                                                                                                                                                                                        |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |              
|Total fixed maturity securities                                                                                                                                                                                                                                                                                                                                                                                                                                                        | 25,132                                                                                                                                                                                                                                                                                                                                                                                                                                                                             | 22,117                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |              
|States, municipalities and political subdivisions                                                                                                                                                                                                                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |              
|**Fixed maturity securities available-for-sale:**                                                                                                                                                                                                                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |              
|Cost or Amortized Cost                                                                                                                                                                                                                                                                                                                                                                                                                                                                 | 7,713                                                                                                                                                                                                                                                                                                                                                                                                                                                                              | 8,918                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |              
|Gross Unrealized Gains                                                                                                                                                                                                                                                                                                                                                                                                                                                                 | 382                                                                                                                                                                                                                                                                                                                                                                                                                                                                                | 338                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |              
|Gross Unrealized Losses                                                                                                                                                                                                                                                                                                                                                                                                                                                                | 703                                                                                                                                                                                                                                                                                                                                                                                                                                                                                | 939                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |              
|Allowance for Credit Losses                                                                                                                                                                                                                                                                                                                                                                                                                                                            | 0                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | 0                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |              
|Estimated Fair Value                                                                                                                                                                                                                                                                                                                                                                                                                                                                   | 7,392                                                                                                                                                                                                                                                                                                                                                                                                                                                                              | 8,317                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |              
|**Debt Securities, Trading, Unrealized Gain (Loss) [Abstract]**                                                                                                                                                                                                                                                                                                                                                                                                                        |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |              
|Total fixed maturity securities                                                                                                                                                                                                                                                                                                                                                                                                                                                        | 7,392                                                                                                                                                                                                                                                                                                                                                                                                                                                                              | 8,317                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |              
|Residential mortgage-backed                                                                                                                                                                                                                                                                                                                                                                                                                                                            |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |              
|**Fixed maturity securities available-for-sale:**                                                                                                                                                                                                                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |              
|Cost or Amortized Cost                                                                                                                                                                                                                                                                                                                                                                                                                                                                 | 3,411                                                                                                                                                                                                                                                                                                                                                                                                                                                                              | 3,073                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |              
|Gross Unrealized Gains                                                                                                                                                                                                                                                                                                                                                                                                                                                                 | 16                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 | 5                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |              
|Gross Unrealized Losses                                                                                                                                                                                                                                                                                                                                                                                                                                                                | 425                                                                                                                                                                                                                                                                                                                                                                                                                                                                                | 447                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |              
|Allowance for Credit Losses                                                                                                                                                                                                                                                                                                                                                                                                                                                            | 0                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | 0                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |              
|Estimated Fair Value                                                                                                                                                                                                                                                                                                                                                                                                                                                                   | 3,002                                                                                                                                                                                                                                                                                                                                                                                                                                                                              | 2,631                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |              
|Commercial mortgage-backed                                                                                                                                                                                                                                                                                                                                                                                                                                                             |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |              
|**Fixed maturity securities available-for-sale:**                                                                                                                                                                                                                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |              
|Cost or Amortized Cost                                                                                                                                                                                                                                                                                                                                                                                                                                                                 | 1,862                                                                                                                                                                                                                                                                                                                                                                                                                                                                              | 1,886                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |              
|Gross Unrealized Gains                                                                                                                                                                                                                                                                                                                                                                                                                                                                 | 7                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | 4                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |              
|Gross Unrealized Losses                                                                                                                                                                                                                                                                                                                                                                                                                                                                | 230                                                                                                                                                                                                                                                                                                                                                                                                                                                                                | 255                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |              
|Allowance for Credit Losses                                                                                                                                                                                                                                                                                                                                                                                                                                                            | 8                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | 0                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |              
|Estimated Fair Value                                                                                                                                                                                                                                                                                                                                                                                                                                                                   | 1,631                                                                                                                                                                                                                                                                                                                                                                                                                                                                              | 1,635                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |              
|Other asset-backed                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |              
|**Fixed maturity securities available-for-sale:**                                                                                                                                                                                                                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |              
|Cost or Amortized Cost                                                                                                                                                                                                                                                                                                                                                                                                                                                                 | 3,515                                                                                                                                                                                                                                                                                                                                                                                                                                                                              | 3,287                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |              
|Gross Unrealized Gains                                                                                                                                                                                                                                                                                                                                                                                                                                                                 | 13                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 | 2                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |              
|Gross Unrealized Losses                                                                                                                                                                                                                                                                                                                                                                                                                                                                | 256                                                                                                                                                                                                                                                                                                                                                                                                                                                                                | 361                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |              
|Allowance for Credit Losses                                                                                                                                                                                                                                                                                                                                                                                                                                                            | 4                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | 1                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |              
|Estimated Fair Value                                                                                                                                                                                                                                                                                                                                                                                                                                                                   | 3,268                                                                                                                                                                                                                                                                                                                                                                                                                                                                              | 2,927                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |              
|Asset-backed                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |              
|**Fixed maturity securities available-for-sale:**                                                                                                                                                                                                                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |              
|Cost or Amortized Cost                                                                                                                                                                                                                                                                                                                                                                                                                                                                 | 8,788                                                                                                                                                                                                                                                                                                                                                                                                                                                                              | 8,246                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |              
|Gross Unrealized Gains                                                                                                                                                                                                                                                                                                                                                                                                                                                                 | 36                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 | 11                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |              
|Gross Unrealized Losses                                                                                                                                                                                                                                                                                                                                                                                                                                                                | 911                                                                                                                                                                                                                                                                                                                                                                                                                                                                                | 1,063                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |              
|Allowance for Credit Losses                                                                                                                                                                                                                                                                                                                                                                                                                                                            | 12                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 | 1                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |              
|Estimated Fair Value                                                                                                                                                                                                                                                                                                                                                                                                                                                                   | 7,901                                                                                                                                                                                                                                                                                                                                                                                                                                                                              | 7,193                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |              
|**Debt Securities, Trading, Unrealized Gain (Loss) [Abstract]**                                                                                                                                                                                                                                                                                                                                                                                                                        |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |              
|Total fixed maturity securities                                                                                                                                                                                                                                                                                                                                                                                                                                                        | 7,901                                                                                                                                                                                                                                                                                                                                                                                                                                                                              | 7,193                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |              
|U.S. Treasury and obligations of government-sponsored enterprises                                                                                                                                                                                                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |              
|**Fixed maturity securities available-for-sale:**                                                                                                                                                                                                                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |              
|Cost or Amortized Cost                                                                                                                                                                                                                                                                                                                                                                                                                                                                 | 152                                                                                                                                                                                                                                                                                                                                                                                                                                                                                | 111                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |              
|Gross Unrealized Gains                                                                                                                                                                                                                                                                                                                                                                                                                                                                 | 1                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | 1                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |              
|Gross Unrealized Losses                                                                                                                                                                                                                                                                                                                                                                                                                                                                | 2                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | 2                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |              
|Allowance for Credit Losses                                                                                                                                                                                                                                                                                                                                                                                                                                                            | 0                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | 0                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |              
|Estimated Fair Value                                                                                                                                                                                                                                                                                                                                                                                                                                                                   | 151                                                                                                                                                                                                                                                                                                                                                                                                                                                                                | 110                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |              
|Foreign government                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |              
|**Fixed maturity securities available-for-sale:**                                                                                                                                                                                                                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |              
|Cost or Amortized Cost                                                                                                                                                                                                                                                                                                                                                                                                                                                                 | 741                                                                                                                                                                                                                                                                                                                                                                                                                                                                                | 617                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |              
|Gross Unrealized Gains                                                                                                                                                                                                                                                                                                                                                                                                                                                                 | 6                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | 1                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |              
|Gross Unrealized Losses                                                                                                                                                                                                                                                                                                                                                                                                                                                                | 34                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 | 43                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |              
|Allowance for Credit Losses                                                                                                                                                                                                                                                                                                                                                                                                                                                            | 0                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | 0                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |              
|Estimated Fair Value                                                                                                                                                                                                                                                                                                                                                                                                                                                                   | 713                                                                                                                                                                                                                                                                                                                                                                                                                                                                                | 575                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |              
|Redeemable preferred stock                                                                                                                                                                                                                                                                                                                                                                                                                                                             |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |              
|**Fixed maturity securities available-for-sale:**                                                                                                                                                                                                                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |              
|Cost or Amortized Cost                                                                                                                                                                                                                                                                                                                                                                                                                                                                 | 0                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | 3                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |              
|Gross Unrealized Gains                                                                                                                                                                                                                                                                                                                                                                                                                                                                 | 0                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | 0                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |              
|Gross Unrealized Losses                                                                                                                                                                                                                                                                                                                                                                                                                                                                | 0                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | 0                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |              
|Allowance for Credit Losses                                                                                                                                                                                                                                                                                                                                                                                                                                                            | 0                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | 0                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |              
|Estimated Fair Value                                                                                                                                                                                                                                                                                                                                                                                                                                                                   | $ 0                                                                                                                                                                                                                                                                                                                                                                                                                                                                                | $ 3                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |              
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      
|[1]
As of January 1, 2023, the Company adopted ASU 2018-12, Financial Services-Insurance (Topic 944): Targeted Improvements to the Accounting for Long-Duration Contracts(ASU 2018-12) using the modified retrospective method applied as of the transition date of January 1, 2021.  Prior period amounts in the financial statements have been adjusted to reflect application of the new guidance.  See Note A to the Consolidated Financial Statements for additional information. | [1]                                                                                                                                                                                                                                                                                                                                                                                                                                                                                | As of January 1, 2023, the Company adopted ASU 2018-12, Financial Services-Insurance (Topic 944): Targeted Improvements to the Accounting for Long-Duration Contracts(ASU 2018-12) using the modified retrospective method applied as of the transition date of January 1, 2021.  Prior period amounts in the financial statements have been adjusted to reflect application of the new guidance.  See Note A to the Consolidated Financial Statements for additional information.
|[1]                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    | As of January 1, 2023, the Company adopted ASU 2018-12, Financial Services-Insurance (Topic 944): Targeted Improvements to the Accounting for Long-Duration Contracts(ASU 2018-12) using the modified retrospective method applied as of the transition date of January 1, 2021.  Prior period amounts in the financial statements have been adjusted to reflect application of the new guidance.  See Note A to the Consolidated Financial Statements for additional information.

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