| **Deferred Policy Acquisition Costs - Life Deferred Acquisition Costs Rollforward by Product (Details) - USD ($) $ in Millions** | 3 Months Ended | 9 Months Ended |
|----------------------------------------------------------------------------------------------------------------------------------|----------------|----------------|
||
| **Movement Analysis of Deferred Policy Acquisition Costs**                                                                       |           |           |   |   |
| Deferred policy acquisition costs asset, beginning of period                                                                     | $ 1,229        | $ 1,109        | $ 1,093 | $ 1,013 |
| Capitalized deferred policy acquisition costs                                                                                    | 447            | 365            | 1,351 | 1,166 |
| Amortized deferred policy acquisition costs                                                                                      | (435)          | (373)          | (1,203) | (1,078) |
| Deferred policy acquisition costs asset, end of period                                                                           | 1,241          | 1,101          | 1,241 | 1,101 |
| Term Life Insurance                                                                                                              |           |           |   |   |
| **Movement Analysis of Deferred Policy Acquisition Costs**                                                                       |           |           |   |   |
| Deferred policy acquisition costs asset, beginning of period                                                                     | 241            | 233            | 236 | 228 |
| Capitalized deferred policy acquisition costs                                                                                    | 9              | 8              | 25 | 24 |
| Amortized deferred policy acquisition costs                                                                                      | (7)            | (7)            | (18) | (18) |
| Deferred policy acquisition costs asset, end of period                                                                           | 243            | 234            | 243 | 234 |
| Whole Life Insurance                                                                                                             |           |           |   |   |
| **Movement Analysis of Deferred Policy Acquisition Costs**                                                                       |           |           |   |   |
| Deferred policy acquisition costs asset, beginning of period                                                                     | 50             | 45             | 48 | 43 |
| Capitalized deferred policy acquisition costs                                                                                    | 1              | 2              | 5 | 6 |
| Amortized deferred policy acquisition costs                                                                                      | 0              | 0              | (2) | (2) |
| Deferred policy acquisition costs asset, end of period                                                                           | 51             | 47             | 51 | 47 |
| Deferred Fixed Annuity                                                                                                           |           |           |   |   |
| **Movement Analysis of Deferred Policy Acquisition Costs**                                                                       |           |           |   |   |
| Deferred policy acquisition costs asset, beginning of period                                                                     | 8              | 8              | 8 | 7 |
| Capitalized deferred policy acquisition costs                                                                                    | 0              | 0              | 1 | 1 |
| Amortized deferred policy acquisition costs                                                                                      | 0              | 0              | (1) | 0 |
| Deferred policy acquisition costs asset, end of period                                                                           | 8              | 8              | 8 | 8 |
| Universal life                                                                                                                   |           |           |   |   |
| **Movement Analysis of Deferred Policy Acquisition Costs**                                                                       |           |           |   |   |
| Deferred policy acquisition costs asset, beginning of period                                                                     | 52             | 52             | 52 | 53 |
| Capitalized deferred policy acquisition costs                                                                                    | 1              | 0              | 2 | 1 |
| Amortized deferred policy acquisition costs                                                                                      | (1)            | 0              | (2) | (2) |
| Deferred policy acquisition costs asset, end of period                                                                           | 52             | 52             | 52 | 52 |
| Life Insurance Segment                                                                                                           |           |           |   |   |
| **Movement Analysis of Deferred Policy Acquisition Costs**                                                                       |           |           |   |   |
| Deferred policy acquisition costs asset, beginning of period                                                                     | 351            | 338            | 344 | 331 |
| Capitalized deferred policy acquisition costs                                                                                    | 11             | 10             | 33 | 32 |
| Amortized deferred policy acquisition costs                                                                                      | (8)            | (7)            | (23) | (22) |
| Deferred policy acquisition costs asset, end of period                                                                           | $ 354          | $ 341          | $ 354 | $ 341 |

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|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of amortization expense (reversal of expense) for deferred policy acquisition costs.
+ References
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|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of deferred policy acquisition cost capitalized on contract remaining in force.
+ References
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|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of deferred policy acquisition cost capitalized.
+ References
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|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.
+ References
No definition available.
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