|**Business Segments (Balance Sheet Information) (Details) - USD ($) $ in Millions**                                                                                                                                                                                                                                                                                  | Sep. 30, 2023                                                                                                                                                                                                                                                                                                                                                    | Dec. 31, 2022                                                                                                                                                                                                                                                                                                                                                    | Sep. 30, 2022 | Dec. 31, 2020
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------------- | -------------
|**Segment Reporting Information [Line Items]**                                                                                                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                  |               |              
|Reinsurance receivables                                                                                                                                                                                                                                                                                                                                              | $ 5,469                                                                                                                                                                                                                                                                                                                                                          | $ 5,438                                                                                                                                                                                                                                                                                                                                                          |               |              
|Insurance receivables                                                                                                                                                                                                                                                                                                                                                | 3,240                                                                                                                                                                                                                                                                                                                                                            | 3,187                                                                                                                                                                                                                                                                                                                                                            |               |              
|Deferred acquisition costs                                                                                                                                                                                                                                                                                                                                           | 880                                                                                                                                                                                                                                                                                                                                                              | 806                                                                                                                                                                                                                                                                                                                                                              | [1]           |              
|Goodwill                                                                                                                                                                                                                                                                                                                                                             | 145                                                                                                                                                                                                                                                                                                                                                              | 144                                                                                                                                                                                                                                                                                                                                                              | [1]           |              
|Deferred non-insurance warranty acquisition expense                                                                                                                                                                                                                                                                                                                  | 3,688                                                                                                                                                                                                                                                                                                                                                            | 3,671                                                                                                                                                                                                                                                                                                                                                            | [1]           |              
|**Insurance reserves**                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                  |               |              
|Claim and claim adjustment expenses                                                                                                                                                                                                                                                                                                                                  | 22,836                                                                                                                                                                                                                                                                                                                                                           | 22,120                                                                                                                                                                                                                                                                                                                                                           | [1]           |              
|Unearned premiums                                                                                                                                                                                                                                                                                                                                                    | 6,789                                                                                                                                                                                                                                                                                                                                                            | 6,374                                                                                                                                                                                                                                                                                                                                                            | [1]           |              
|Future policy benefits                                                                                                                                                                                                                                                                                                                                               | 12,654                                                                                                                                                                                                                                                                                                                                                           | 13,480                                                                                                                                                                                                                                                                                                                                                           | [1]           | $ 13,181     
|Deferred non-insurance warranty revenue                                                                                                                                                                                                                                                                                                                              | 4,736                                                                                                                                                                                                                                                                                                                                                            | 4,714                                                                                                                                                                                                                                                                                                                                                            | [1]           |              
|Operating Segments | Specialty                                                                                                                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                  |               |              
|**Segment Reporting Information [Line Items]**                                                                                                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                  |               |              
|Reinsurance receivables                                                                                                                                                                                                                                                                                                                                              | 1,384                                                                                                                                                                                                                                                                                                                                                            | 1,384                                                                                                                                                                                                                                                                                                                                                            |               |              
|Insurance receivables                                                                                                                                                                                                                                                                                                                                                | 1,010                                                                                                                                                                                                                                                                                                                                                            | 1,082                                                                                                                                                                                                                                                                                                                                                            |               |              
|Deferred acquisition costs                                                                                                                                                                                                                                                                                                                                           | 398                                                                                                                                                                                                                                                                                                                                                              | 381                                                                                                                                                                                                                                                                                                                                                              |               |              
|Goodwill                                                                                                                                                                                                                                                                                                                                                             | 117                                                                                                                                                                                                                                                                                                                                                              | 117                                                                                                                                                                                                                                                                                                                                                              |               |              
|Deferred non-insurance warranty acquisition expense                                                                                                                                                                                                                                                                                                                  | 3,688                                                                                                                                                                                                                                                                                                                                                            | 3,671                                                                                                                                                                                                                                                                                                                                                            |               |              
|**Insurance reserves**                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                  |               |              
|Claim and claim adjustment expenses                                                                                                                                                                                                                                                                                                                                  | 7,090                                                                                                                                                                                                                                                                                                                                                            | 6,878                                                                                                                                                                                                                                                                                                                                                            |               |              
|Unearned premiums                                                                                                                                                                                                                                                                                                                                                    | 3,202                                                                                                                                                                                                                                                                                                                                                            | 3,193                                                                                                                                                                                                                                                                                                                                                            |               |              
|Future policy benefits                                                                                                                                                                                                                                                                                                                                               | 0                                                                                                                                                                                                                                                                                                                                                                | 0                                                                                                                                                                                                                                                                                                                                                                |               |              
|Deferred non-insurance warranty revenue                                                                                                                                                                                                                                                                                                                              | 4,736                                                                                                                                                                                                                                                                                                                                                            | 4,714                                                                                                                                                                                                                                                                                                                                                            |               |              
|Operating Segments | Commercial                                                                                                                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                  |               |              
|**Segment Reporting Information [Line Items]**                                                                                                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                  |               |              
|Reinsurance receivables                                                                                                                                                                                                                                                                                                                                              | 1,217                                                                                                                                                                                                                                                                                                                                                            | 1,062                                                                                                                                                                                                                                                                                                                                                            |               |              
|Insurance receivables                                                                                                                                                                                                                                                                                                                                                | 1,880                                                                                                                                                                                                                                                                                                                                                            | 1,728                                                                                                                                                                                                                                                                                                                                                            |               |              
|Deferred acquisition costs                                                                                                                                                                                                                                                                                                                                           | 358                                                                                                                                                                                                                                                                                                                                                              | 321                                                                                                                                                                                                                                                                                                                                                              |               |              
|Goodwill                                                                                                                                                                                                                                                                                                                                                             | 0                                                                                                                                                                                                                                                                                                                                                                | 0                                                                                                                                                                                                                                                                                                                                                                |               |              
|Deferred non-insurance warranty acquisition expense                                                                                                                                                                                                                                                                                                                  | 0                                                                                                                                                                                                                                                                                                                                                                | 0                                                                                                                                                                                                                                                                                                                                                                |               |              
|**Insurance reserves**                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                  |               |              
|Claim and claim adjustment expenses                                                                                                                                                                                                                                                                                                                                  | 9,902                                                                                                                                                                                                                                                                                                                                                            | 9,395                                                                                                                                                                                                                                                                                                                                                            |               |              
|Unearned premiums                                                                                                                                                                                                                                                                                                                                                    | 2,764                                                                                                                                                                                                                                                                                                                                                            | 2,425                                                                                                                                                                                                                                                                                                                                                            |               |              
|Future policy benefits                                                                                                                                                                                                                                                                                                                                               | 0                                                                                                                                                                                                                                                                                                                                                                | 0                                                                                                                                                                                                                                                                                                                                                                |               |              
|Deferred non-insurance warranty revenue                                                                                                                                                                                                                                                                                                                              | 0                                                                                                                                                                                                                                                                                                                                                                | 0                                                                                                                                                                                                                                                                                                                                                                |               |              
|Operating Segments | International                                                                                                                                                                                                                                                                                                                                   |                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                  |               |              
|**Segment Reporting Information [Line Items]**                                                                                                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                  |               |              
|Reinsurance receivables                                                                                                                                                                                                                                                                                                                                              | 455                                                                                                                                                                                                                                                                                                                                                              | 414                                                                                                                                                                                                                                                                                                                                                              |               |              
|Insurance receivables                                                                                                                                                                                                                                                                                                                                                | 346                                                                                                                                                                                                                                                                                                                                                              | 369                                                                                                                                                                                                                                                                                                                                                              |               |              
|Deferred acquisition costs                                                                                                                                                                                                                                                                                                                                           | 124                                                                                                                                                                                                                                                                                                                                                              | 104                                                                                                                                                                                                                                                                                                                                                              |               |              
|Goodwill                                                                                                                                                                                                                                                                                                                                                             | 28                                                                                                                                                                                                                                                                                                                                                               | 27                                                                                                                                                                                                                                                                                                                                                               |               |              
|Deferred non-insurance warranty acquisition expense                                                                                                                                                                                                                                                                                                                  | 0                                                                                                                                                                                                                                                                                                                                                                | 0                                                                                                                                                                                                                                                                                                                                                                |               |              
|**Insurance reserves**                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                  |               |              
|Claim and claim adjustment expenses                                                                                                                                                                                                                                                                                                                                  | 2,572                                                                                                                                                                                                                                                                                                                                                            | 2,403                                                                                                                                                                                                                                                                                                                                                            |               |              
|Unearned premiums                                                                                                                                                                                                                                                                                                                                                    | 717                                                                                                                                                                                                                                                                                                                                                              | 653                                                                                                                                                                                                                                                                                                                                                              |               |              
|Future policy benefits                                                                                                                                                                                                                                                                                                                                               | 0                                                                                                                                                                                                                                                                                                                                                                | 0                                                                                                                                                                                                                                                                                                                                                                |               |              
|Deferred non-insurance warranty revenue                                                                                                                                                                                                                                                                                                                              | 0                                                                                                                                                                                                                                                                                                                                                                | 0                                                                                                                                                                                                                                                                                                                                                                |               |              
|Operating Segments | Life & Group                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                  |               |              
|**Segment Reporting Information [Line Items]**                                                                                                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                  |               |              
|Reinsurance receivables                                                                                                                                                                                                                                                                                                                                              | 97                                                                                                                                                                                                                                                                                                                                                               | 101                                                                                                                                                                                                                                                                                                                                                              |               |              
|Insurance receivables                                                                                                                                                                                                                                                                                                                                                | 4                                                                                                                                                                                                                                                                                                                                                                | 8                                                                                                                                                                                                                                                                                                                                                                |               |              
|Deferred acquisition costs                                                                                                                                                                                                                                                                                                                                           | 0                                                                                                                                                                                                                                                                                                                                                                | 0                                                                                                                                                                                                                                                                                                                                                                |               |              
|Goodwill                                                                                                                                                                                                                                                                                                                                                             | 0                                                                                                                                                                                                                                                                                                                                                                | 0                                                                                                                                                                                                                                                                                                                                                                |               |              
|Deferred non-insurance warranty acquisition expense                                                                                                                                                                                                                                                                                                                  | 0                                                                                                                                                                                                                                                                                                                                                                | 0                                                                                                                                                                                                                                                                                                                                                                |               |              
|**Insurance reserves**                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                  |               |              
|Claim and claim adjustment expenses                                                                                                                                                                                                                                                                                                                                  | 649                                                                                                                                                                                                                                                                                                                                                              | 695                                                                                                                                                                                                                                                                                                                                                              |               |              
|Unearned premiums                                                                                                                                                                                                                                                                                                                                                    | 106                                                                                                                                                                                                                                                                                                                                                              | 103                                                                                                                                                                                                                                                                                                                                                              |               |              
|Future policy benefits                                                                                                                                                                                                                                                                                                                                               | 12,654                                                                                                                                                                                                                                                                                                                                                           | 13,480                                                                                                                                                                                                                                                                                                                                                           |               |              
|Deferred non-insurance warranty revenue                                                                                                                                                                                                                                                                                                                              | 0                                                                                                                                                                                                                                                                                                                                                                | 0                                                                                                                                                                                                                                                                                                                                                                |               |              
|Operating Segments | Corporate & Other                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                  |               |              
|**Segment Reporting Information [Line Items]**                                                                                                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                  |               |              
|Reinsurance receivables                                                                                                                                                                                                                                                                                                                                              | 2,316                                                                                                                                                                                                                                                                                                                                                            | 2,477                                                                                                                                                                                                                                                                                                                                                            |               |              
|Insurance receivables                                                                                                                                                                                                                                                                                                                                                | 0                                                                                                                                                                                                                                                                                                                                                                | 0                                                                                                                                                                                                                                                                                                                                                                |               |              
|Deferred acquisition costs                                                                                                                                                                                                                                                                                                                                           | 0                                                                                                                                                                                                                                                                                                                                                                | 0                                                                                                                                                                                                                                                                                                                                                                |               |              
|Goodwill                                                                                                                                                                                                                                                                                                                                                             | 0                                                                                                                                                                                                                                                                                                                                                                | 0                                                                                                                                                                                                                                                                                                                                                                |               |              
|Deferred non-insurance warranty acquisition expense                                                                                                                                                                                                                                                                                                                  | 0                                                                                                                                                                                                                                                                                                                                                                | 0                                                                                                                                                                                                                                                                                                                                                                |               |              
|**Insurance reserves**                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                  |               |              
|Claim and claim adjustment expenses                                                                                                                                                                                                                                                                                                                                  | 2,623                                                                                                                                                                                                                                                                                                                                                            | 2,749                                                                                                                                                                                                                                                                                                                                                            |               |              
|Unearned premiums                                                                                                                                                                                                                                                                                                                                                    | 0                                                                                                                                                                                                                                                                                                                                                                | 0                                                                                                                                                                                                                                                                                                                                                                |               |              
|Future policy benefits                                                                                                                                                                                                                                                                                                                                               | 0                                                                                                                                                                                                                                                                                                                                                                | 0                                                                                                                                                                                                                                                                                                                                                                |               |              
|Deferred non-insurance warranty revenue                                                                                                                                                                                                                                                                                                                              | 0                                                                                                                                                                                                                                                                                                                                                                | 0                                                                                                                                                                                                                                                                                                                                                                |               |              
|Eliminations                                                                                                                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                  |               |              
|**Segment Reporting Information [Line Items]**                                                                                                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                  |               |              
|Reinsurance receivables                                                                                                                                                                                                                                                                                                                                              | 0                                                                                                                                                                                                                                                                                                                                                                | 0                                                                                                                                                                                                                                                                                                                                                                |               |              
|Insurance receivables                                                                                                                                                                                                                                                                                                                                                | 0                                                                                                                                                                                                                                                                                                                                                                | 0                                                                                                                                                                                                                                                                                                                                                                |               |              
|Deferred acquisition costs                                                                                                                                                                                                                                                                                                                                           | 0                                                                                                                                                                                                                                                                                                                                                                | 0                                                                                                                                                                                                                                                                                                                                                                |               |              
|Goodwill                                                                                                                                                                                                                                                                                                                                                             | 0                                                                                                                                                                                                                                                                                                                                                                | 0                                                                                                                                                                                                                                                                                                                                                                |               |              
|Deferred non-insurance warranty acquisition expense                                                                                                                                                                                                                                                                                                                  | 0                                                                                                                                                                                                                                                                                                                                                                | 0                                                                                                                                                                                                                                                                                                                                                                |               |              
|**Insurance reserves**                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                  |               |              
|Claim and claim adjustment expenses                                                                                                                                                                                                                                                                                                                                  | 0                                                                                                                                                                                                                                                                                                                                                                | 0                                                                                                                                                                                                                                                                                                                                                                |               |              
|Unearned premiums                                                                                                                                                                                                                                                                                                                                                    | 0                                                                                                                                                                                                                                                                                                                                                                | 0                                                                                                                                                                                                                                                                                                                                                                |               |              
|Future policy benefits                                                                                                                                                                                                                                                                                                                                               | 0                                                                                                                                                                                                                                                                                                                                                                | 0                                                                                                                                                                                                                                                                                                                                                                |               |              
|Deferred non-insurance warranty revenue                                                                                                                                                                                                                                                                                                                              | $ 0                                                                                                                                                                                                                                                                                                                                                              | $ 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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