| **Reinsurance - Life Insurance Ceded Business (Details) - USD ($) $ in Millions** | 3 Months Ended | 9 Months Ended |
|-----------------------------------------------------------------------------------|----------------|----------------|
||
| **Reinsurance for Insurance Companies, by Product Segment**                       |           |           |   |   |
| Insurance losses and contract holders' benefits                                   | $ 1,578        | $ 1,332        | $ 4,407 | $ 4,070 |
| Life Insurance Segment                                                            |           |           |   |   |
| **Reinsurance for Insurance Companies, by Product Segment**                       |           |           |   |   |
| Direct earned premiums                                                            | 101            | 97             | 301 | 293 |
| Ceded earned premiums                                                             | (21)           | (21)           | (61) | (60) |
| Earned premiums                                                                   | 80             | 76             | 240 | 233 |
| Direct contract holders' benefits incurred                                        | 92             | 92             | 262 | 289 |
| Ceded contract holders' benefits incurred                                         | (13)           | (21)           | (36) | (59) |
| Insurance losses and contract holders' benefits                                   | $ 79           | $ 71           | $ 226 | $ 230 |

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|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - References
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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.
+ References
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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.
+ References
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| - Definition
Amount of reduction of provision for policy benefits and costs incurred for policies ceded.
+ References
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