| **Reinsurance - Life Insurance Ceded Business (Detail) - USD ($) $ in Millions** | 3 Months Ended | 9 Months Ended |
|----------------------------------------------------------------------------------|----------------|----------------|
||
| **Reinsurance for Insurance Companies, by Product Segment [Line Items]**         |           |           |   |   |
| Insurance losses and contract holders' benefits                                  | $ 1,143        | $ 932          | $ 3,232 | $ 2,728 |
| Life Insurance Segment                                                           |           |           |   |   |
| **Reinsurance for Insurance Companies, by Product Segment [Line Items]**         |           |           |   |   |
| Direct earned premiums                                                           | 90             | 87             | 273 | 256 |
| Ceded earned premiums                                                            | (18)           | (17)           | (55) | (53) |
| Earned premiums                                                                  | 72             | 70             | 218 | 203 |
| Direct contract holders' benefits incurred                                       | 85             | 87             | 270 | 259 |
| Ceded contract holders' benefits incurred                                        | (13)           | (19)           | (46) | (48) |
| Insurance losses and contract holders' benefits                                  | $ 72           | $ 68           | $ 224 | $ 211 |

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|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of earned premiums ceded to other entities.
+ References
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| - Definition
Amount, before premiums ceded to other entities and premiums assumed by the entity, of premiums earned.
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| - Definition
Amount, before effect of policies assumed or ceded, of expense related to provision for policy benefits and costs incurred.
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| - Definition
Amount, after effects of policies assumed or ceded, of expense related to the provision for policy benefits and costs incurred.
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| - Definition
Amount, after premiums ceded to other entities and premiums assumed by the entity, of life premiums earned.
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Amount of reduction of provision for policy benefits and costs incurred for policies ceded.
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