| **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                                                                     | $ 1,109        | $ 1,046        | $ 1,013 | $ 916 |
| Capitalized deferred policy acquisition costs                                                                                    | 365            | 336            | 1,166 | 1,097 |
| Amortized deferred policy acquisition costs                                                                                      | (373)          | (349)          | (1,078) | (980) |
| Deferred policy acquisition costs asset, end of period                                                                           | 1,101          | 1,033          | 1,101 | 1,033 |
| Term Life Insurance                                                                                                              |           |           |   |   |
| **Movement Analysis of Deferred Policy Acquisition Costs**                                                                       |           |           |   |   |
| Deferred policy acquisition costs asset, beginning of period                                                                     | 233            | 222            | 228 | 215 |
| Capitalized deferred policy acquisition costs                                                                                    | 8              | 9              | 24 | 27 |
| Amortized deferred policy acquisition costs                                                                                      | (7)            | (5)            | (18) | (16) |
| Deferred policy acquisition costs asset, end of period                                                                           | 234            | 226            | 234 | 226 |
| Whole Life Insurance                                                                                                             |           |           |   |   |
| **Movement Analysis of Deferred Policy Acquisition Costs**                                                                       |           |           |   |   |
| Deferred policy acquisition costs asset, beginning of period                                                                     | 45             | 40             | 43 | 38 |
| Capitalized deferred policy acquisition costs                                                                                    | 2              | 2              | 6 | 5 |
| Amortized deferred policy acquisition costs                                                                                      | 0              | (1)            | (2) | (2) |
| Deferred policy acquisition costs asset, end of period                                                                           | 47             | 41             | 47 | 41 |
| Deferred Fixed Annuity                                                                                                           |           |           |   |   |
| **Movement Analysis of Deferred Policy Acquisition Costs**                                                                       |           |           |   |   |
| Deferred policy acquisition costs asset, beginning of period                                                                     | 8              | 7              | 7 | 7 |
| Capitalized deferred policy acquisition costs                                                                                    | 0              | 0              | 1 | 0 |
| Amortized deferred policy acquisition costs                                                                                      | 0              | 0              | 0 | 0 |
| Deferred policy acquisition costs asset, end of period                                                                           | 8              | 7              | 8 | 7 |
| Universal life                                                                                                                   |           |           |   |   |
| **Movement Analysis of Deferred Policy Acquisition Costs**                                                                       |           |           |   |   |
| Deferred policy acquisition costs asset, beginning of period                                                                     | 52             | 54             | 53 | 54 |
| Capitalized deferred policy acquisition costs                                                                                    | 0              | 0              | 1 | 1 |
| Amortized deferred policy acquisition costs                                                                                      | 0              | (1)            | (2) | (2) |
| Deferred policy acquisition costs asset, end of period                                                                           | 52             | 53             | 52 | 53 |
| Life Insurance Segment                                                                                                           |           |           |   |   |
| **Movement Analysis of Deferred Policy Acquisition Costs**                                                                       |           |           |   |   |
| Deferred policy acquisition costs asset, beginning of period                                                                     | 338            | 323            | 331 | 314 |
| Capitalized deferred policy acquisition costs                                                                                    | 10             | 11             | 32 | 33 |
| Amortized deferred policy acquisition costs                                                                                      | (7)            | (7)            | (22) | (20) |
| Deferred policy acquisition costs asset, end of period                                                                           | $ 341          | $ 327          | $ 341 | $ 327 |

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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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