| **Undiscounted and Discounted Future Benefit Payments and Gross Premiums (Details) - Life policy reserves: - USD ($) $ in Millions** | Sep. 30, 2024 | Jun. 30, 2024 | Dec. 31, 2023 | Sep. 30, 2023 | Jun. 30, 2023 | Dec. 31, 2022 |
|--------------------------------------------------------------------------------------------------------------------------------------|---------------|---------------|---------------|---------------|---------------|---------------|
| Term Life Insurance                                                                                                                  |          |          |          |          |          |          |
| **Liability for Future Policy Benefit, Activity [Line Items]**                                                                       |          |          |          |          |          |          |
| Undiscounted expected future benefit payments                                                                                        | $ 4,840       |          |          | $ 4,768       |          |          |
| Undiscounted expected future gross premiums                                                                                          | 4,524         |          |          | 4,364         |          |          |
| Discounted expected future benefit payments                                                                                          | 2,794         | $ 2,634       | $ 2,751       | 2,521         | $ 2,662       | $ 2,584       |
| Discounted expected future gross premiums                                                                                            | 2,736         |          |          | 2,464         |          |          |
| Whole Life Insurance                                                                                                                 |          |          |          |          |          |          |
| **Liability for Future Policy Benefit, Activity [Line Items]**                                                                       |          |          |          |          |          |          |
| Undiscounted expected future benefit payments                                                                                        | 1,702         |          |          | 1,631         |          |          |
| Undiscounted expected future gross premiums                                                                                          | 687           |          |          | 653           |          |          |
| Discounted expected future benefit payments                                                                                          | 668           | $ 619         | $ 657         | 586           | $ 633         | $ 614         |
| Discounted expected future gross premiums                                                                                            | $ 428         |          |          | $ 379         |          |          |

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| - Definition
Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.
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Amount, before effect of reinsurance, of discounted balance for expected future gross premium component of liability for future policy benefit.
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Amount, before effect of reinsurance, of undiscounted balance for expected future gross premium component of liability for future policy benefit.
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Amount, before effect of reinsurance and after current period update of cash flow assumption and discount rate change, of expected future policy benefit and expense component of liability for future policy benefit.
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Amount, before effect of reinsurance, of undiscounted balance for expected future policy benefit and expense component of liability for future policy benefit.
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| X                                                                                                                                                 |
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