|**Investments (Summary of fixed maturity and equity securities) (Details) - USD ($) $ in Millions**                                                                                                                                                                                                                                                                  | Sep. 30, 2023                                                                                                                                                                                                                                                                                                                                                    | Jun. 30, 2023                                                                                                                                                                                                                                                                                                                                                    | Dec. 31, 2022 | Sep. 30, 2022 | Jun. 30, 2022 | Dec. 31, 2021
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------------- | ------------- | ------------- | -------------
|**Fixed maturity securities available-for-sale:**                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                  |               |               |               |              
|Cost or Amortized Cost                                                                                                                                                                                                                                                                                                                                               | $ 42,364                                                                                                                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                                                                                                                                  | $ 41,032      |               |               |              
|Gross Unrealized Gains                                                                                                                                                                                                                                                                                                                                               | 396                                                                                                                                                                                                                                                                                                                                                              |                                                                                                                                                                                                                                                                                                                                                                  | 652           |               |               |              
|Gross Unrealized Losses                                                                                                                                                                                                                                                                                                                                              | 4,888                                                                                                                                                                                                                                                                                                                                                            |                                                                                                                                                                                                                                                                                                                                                                  | 4,056         |               |               |              
|Allowance for Credit Losses                                                                                                                                                                                                                                                                                                                                          | 18                                                                                                                                                                                                                                                                                                                                                               | $ 22                                                                                                                                                                                                                                                                                                                                                             | 1             |               | $ 3           | $ 5          
|Estimated Fair Value                                                                                                                                                                                                                                                                                                                                                 | 37,854                                                                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                                                                                  | 37,627        |               |               |              
|**Total fixed maturity securities trading**                                                                                                                                                                                                                                                                                                                          |                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                  |               |               |               |              
|Debt securities, amortized cost                                                                                                                                                                                                                                                                                                                                      | 42,366                                                                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                                                                                  | 41,032        |               |               |              
|Total fixed maturity securities                                                                                                                                                                                                                                                                                                                                      | 37,856                                                                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                                                                                  | 37,627        | [1]           |               |              
|Corporate and other bonds                                                                                                                                                                                                                                                                                                                                            |                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                  |               |               |               |              
|**Fixed maturity securities available-for-sale:**                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                  |               |               |               |              
|Cost or Amortized Cost                                                                                                                                                                                                                                                                                                                                               | 24,757                                                                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                                                                                  | 23,137        |               |               |              
|Gross Unrealized Gains                                                                                                                                                                                                                                                                                                                                               | 196                                                                                                                                                                                                                                                                                                                                                              |                                                                                                                                                                                                                                                                                                                                                                  | 301           |               |               |              
|Gross Unrealized Losses                                                                                                                                                                                                                                                                                                                                              | 2,437                                                                                                                                                                                                                                                                                                                                                            |                                                                                                                                                                                                                                                                                                                                                                  | 2,009         |               |               |              
|Allowance for Credit Losses                                                                                                                                                                                                                                                                                                                                          | 5                                                                                                                                                                                                                                                                                                                                                                | 13                                                                                                                                                                                                                                                                                                                                                               | 0             |               | 0             | 0            
|Estimated Fair Value                                                                                                                                                                                                                                                                                                                                                 | 22,511                                                                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                                                                                  | 21,429        |               |               |              
|**Total fixed maturity securities trading**                                                                                                                                                                                                                                                                                                                          |                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                  |               |               |               |              
|Total fixed maturity securities                                                                                                                                                                                                                                                                                                                                      | 23,320                                                                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                                                                                  | 22,117        |               |               |              
|States, municipalities and political subdivisions                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                  |               |               |               |              
|**Fixed maturity securities available-for-sale:**                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                  |               |               |               |              
|Cost or Amortized Cost                                                                                                                                                                                                                                                                                                                                               | 8,003                                                                                                                                                                                                                                                                                                                                                            |                                                                                                                                                                                                                                                                                                                                                                  | 8,918         |               |               |              
|Gross Unrealized Gains                                                                                                                                                                                                                                                                                                                                               | 183                                                                                                                                                                                                                                                                                                                                                              |                                                                                                                                                                                                                                                                                                                                                                  | 338           |               |               |              
|Gross Unrealized Losses                                                                                                                                                                                                                                                                                                                                              | 1,152                                                                                                                                                                                                                                                                                                                                                            |                                                                                                                                                                                                                                                                                                                                                                  | 939           |               |               |              
|Allowance for Credit Losses                                                                                                                                                                                                                                                                                                                                          | 0                                                                                                                                                                                                                                                                                                                                                                |                                                                                                                                                                                                                                                                                                                                                                  | 0             |               |               |              
|Estimated Fair Value                                                                                                                                                                                                                                                                                                                                                 | 7,034                                                                                                                                                                                                                                                                                                                                                            |                                                                                                                                                                                                                                                                                                                                                                  | 8,317         |               |               |              
|**Total fixed maturity securities trading**                                                                                                                                                                                                                                                                                                                          |                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                  |               |               |               |              
|Total fixed maturity securities                                                                                                                                                                                                                                                                                                                                      | 7,034                                                                                                                                                                                                                                                                                                                                                            |                                                                                                                                                                                                                                                                                                                                                                  | 8,317         |               |               |              
|Asset-backed                                                                                                                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                  |               |               |               |              
|**Fixed maturity securities available-for-sale:**                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                  |               |               |               |              
|Cost or Amortized Cost                                                                                                                                                                                                                                                                                                                                               | 8,741                                                                                                                                                                                                                                                                                                                                                            |                                                                                                                                                                                                                                                                                                                                                                  | 8,246         |               |               |              
|Gross Unrealized Gains                                                                                                                                                                                                                                                                                                                                               | 15                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                                                                                                                                                  | 11            |               |               |              
|Gross Unrealized Losses                                                                                                                                                                                                                                                                                                                                              | 1,241                                                                                                                                                                                                                                                                                                                                                            |                                                                                                                                                                                                                                                                                                                                                                  | 1,063         |               |               |              
|Allowance for Credit Losses                                                                                                                                                                                                                                                                                                                                          | 13                                                                                                                                                                                                                                                                                                                                                               | $ 9                                                                                                                                                                                                                                                                                                                                                              | 1             |               | $ 3           | $ 5          
|Estimated Fair Value                                                                                                                                                                                                                                                                                                                                                 | 7,502                                                                                                                                                                                                                                                                                                                                                            |                                                                                                                                                                                                                                                                                                                                                                  | 7,193         |               |               |              
|**Total fixed maturity securities trading**                                                                                                                                                                                                                                                                                                                          |                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                  |               |               |               |              
|Total fixed maturity securities                                                                                                                                                                                                                                                                                                                                      | 7,502                                                                                                                                                                                                                                                                                                                                                            |                                                                                                                                                                                                                                                                                                                                                                  | 7,193         |               |               |              
|Residential mortgage-backed                                                                                                                                                                                                                                                                                                                                          |                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                  |               |               |               |              
|**Fixed maturity securities available-for-sale:**                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                  |               |               |               |              
|Cost or Amortized Cost                                                                                                                                                                                                                                                                                                                                               | 3,425                                                                                                                                                                                                                                                                                                                                                            |                                                                                                                                                                                                                                                                                                                                                                  | 3,073         |               |               |              
|Gross Unrealized Gains                                                                                                                                                                                                                                                                                                                                               | 4                                                                                                                                                                                                                                                                                                                                                                |                                                                                                                                                                                                                                                                                                                                                                  | 5             |               |               |              
|Gross Unrealized Losses                                                                                                                                                                                                                                                                                                                                              | 599                                                                                                                                                                                                                                                                                                                                                              |                                                                                                                                                                                                                                                                                                                                                                  | 447           |               |               |              
|Allowance for Credit Losses                                                                                                                                                                                                                                                                                                                                          | 0                                                                                                                                                                                                                                                                                                                                                                |                                                                                                                                                                                                                                                                                                                                                                  | 0             |               |               |              
|Estimated Fair Value                                                                                                                                                                                                                                                                                                                                                 | 2,830                                                                                                                                                                                                                                                                                                                                                            |                                                                                                                                                                                                                                                                                                                                                                  | 2,631         |               |               |              
|Commercial mortgage-backed                                                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                  |               |               |               |              
|**Fixed maturity securities available-for-sale:**                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                  |               |               |               |              
|Cost or Amortized Cost                                                                                                                                                                                                                                                                                                                                               | 1,833                                                                                                                                                                                                                                                                                                                                                            |                                                                                                                                                                                                                                                                                                                                                                  | 1,886         |               |               |              
|Gross Unrealized Gains                                                                                                                                                                                                                                                                                                                                               | 4                                                                                                                                                                                                                                                                                                                                                                |                                                                                                                                                                                                                                                                                                                                                                  | 4             |               |               |              
|Gross Unrealized Losses                                                                                                                                                                                                                                                                                                                                              | 276                                                                                                                                                                                                                                                                                                                                                              |                                                                                                                                                                                                                                                                                                                                                                  | 255           |               |               |              
|Allowance for Credit Losses                                                                                                                                                                                                                                                                                                                                          | 7                                                                                                                                                                                                                                                                                                                                                                |                                                                                                                                                                                                                                                                                                                                                                  | 0             |               |               |              
|Estimated Fair Value                                                                                                                                                                                                                                                                                                                                                 | 1,554                                                                                                                                                                                                                                                                                                                                                            |                                                                                                                                                                                                                                                                                                                                                                  | 1,635         |               |               |              
|Other asset-backed                                                                                                                                                                                                                                                                                                                                                   |                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                  |               |               |               |              
|**Fixed maturity securities available-for-sale:**                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                  |               |               |               |              
|Cost or Amortized Cost                                                                                                                                                                                                                                                                                                                                               | 3,483                                                                                                                                                                                                                                                                                                                                                            |                                                                                                                                                                                                                                                                                                                                                                  | 3,287         |               |               |              
|Gross Unrealized Gains                                                                                                                                                                                                                                                                                                                                               | 7                                                                                                                                                                                                                                                                                                                                                                |                                                                                                                                                                                                                                                                                                                                                                  | 2             |               |               |              
|Gross Unrealized Losses                                                                                                                                                                                                                                                                                                                                              | 366                                                                                                                                                                                                                                                                                                                                                              |                                                                                                                                                                                                                                                                                                                                                                  | 361           |               |               |              
|Allowance for Credit Losses                                                                                                                                                                                                                                                                                                                                          | 6                                                                                                                                                                                                                                                                                                                                                                |                                                                                                                                                                                                                                                                                                                                                                  | 1             |               |               |              
|Estimated Fair Value                                                                                                                                                                                                                                                                                                                                                 | 3,118                                                                                                                                                                                                                                                                                                                                                            |                                                                                                                                                                                                                                                                                                                                                                  | 2,927         |               |               |              
|U.S. Treasury and obligations of government-sponsored enterprises                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                  |               |               |               |              
|**Fixed maturity securities available-for-sale:**                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                  |               |               |               |              
|Cost or Amortized Cost                                                                                                                                                                                                                                                                                                                                               | 150                                                                                                                                                                                                                                                                                                                                                              |                                                                                                                                                                                                                                                                                                                                                                  | 111           |               |               |              
|Gross Unrealized Gains                                                                                                                                                                                                                                                                                                                                               | 1                                                                                                                                                                                                                                                                                                                                                                |                                                                                                                                                                                                                                                                                                                                                                  | 1             |               |               |              
|Gross Unrealized Losses                                                                                                                                                                                                                                                                                                                                              | 2                                                                                                                                                                                                                                                                                                                                                                |                                                                                                                                                                                                                                                                                                                                                                  | 2             |               |               |              
|Allowance for Credit Losses                                                                                                                                                                                                                                                                                                                                          | 0                                                                                                                                                                                                                                                                                                                                                                |                                                                                                                                                                                                                                                                                                                                                                  | 0             |               |               |              
|Estimated Fair Value                                                                                                                                                                                                                                                                                                                                                 | 149                                                                                                                                                                                                                                                                                                                                                              |                                                                                                                                                                                                                                                                                                                                                                  | 110           |               |               |              
|Foreign government                                                                                                                                                                                                                                                                                                                                                   |                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                  |               |               |               |              
|**Fixed maturity securities available-for-sale:**                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                  |               |               |               |              
|Cost or Amortized Cost                                                                                                                                                                                                                                                                                                                                               | 713                                                                                                                                                                                                                                                                                                                                                              |                                                                                                                                                                                                                                                                                                                                                                  | 617           |               |               |              
|Gross Unrealized Gains                                                                                                                                                                                                                                                                                                                                               | 1                                                                                                                                                                                                                                                                                                                                                                |                                                                                                                                                                                                                                                                                                                                                                  | 1             |               |               |              
|Gross Unrealized Losses                                                                                                                                                                                                                                                                                                                                              | 56                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                                                                                                                                                  | 43            |               |               |              
|Allowance for Credit Losses                                                                                                                                                                                                                                                                                                                                          | 0                                                                                                                                                                                                                                                                                                                                                                |                                                                                                                                                                                                                                                                                                                                                                  | 0             |               |               |              
|Estimated Fair Value                                                                                                                                                                                                                                                                                                                                                 | 658                                                                                                                                                                                                                                                                                                                                                              |                                                                                                                                                                                                                                                                                                                                                                  | 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             |               |               |              
|Total fixed maturity securities trading                                                                                                                                                                                                                                                                                                                              |                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                  |               |               |               |              
|**Total fixed maturity securities trading**                                                                                                                                                                                                                                                                                                                          |                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                  |               |               |               |              
|Cost or Amortized Cost                                                                                                                                                                                                                                                                                                                                               | 2                                                                                                                                                                                                                                                                                                                                                                |                                                                                                                                                                                                                                                                                                                                                                  | 0             |               |               |              
|Estimated Fair Value                                                                                                                                                                                                                                                                                                                                                 | $ 2                                                                                                                                                                                                                                                                                                                                                              |                                                                                                                                                                                                                                                                                                                                                                  | $ 0           |               |               |              
|                                                                                                                                                                                                                                                                                                                                                                    
|[1]
As of January 1, 2023, the Company adopted 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 Condensed Consolidated Financial Statements for additional information. | [1]                                                                                                                                                                                                                                                                                                                                                              | As of January 1, 2023, the Company adopted 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 Condensed Consolidated Financial Statements for additional information.
|[1]                                                                                                                                                                                                                                                                                                                                                                  | As of January 1, 2023, the Company adopted 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 Condensed Consolidated Financial Statements for additional information.

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