| **Deferred Acquisition Costs - Deferred Policy Acquisition Costs and Asset Reconciliation (Detail) (USD $)In Millions, unless otherwise specified** | 3 Months Ended |
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| **Movement Analysis of Deferred Policy Acquisition Costs [Roll Forward]**                                                                           |           |   |
| Deferred policy acquisition costs asset at beginning of period                                                                                      | $ 470          | $ 477 |
| Capitalized deferred policy acquisition costs                                                                                                       | 198            | 170 |
| Amortized deferred policy acquisition costs                                                                                                         | (179)          | (156) |
| Amortized shadow deferred policy acquisition costs                                                                                                  | 2              | (8) |
| Deferred policy acquisition costs asset at end of period                                                                                            | $ 491          | $ 483 |

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| - Definition
Amount of amortization of deferred policy acquisition costs due to realized investment gains or losses.
+ References
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| - Definition
Amount of amortization of deferred policy acquisition costs due to unrealized investment gains or losses.
+ References
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| - Definition
Net amount of deferred policy acquisition costs capitalized on contracts remaining in force as of the balance sheet date.
+ References
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| - Definition
Total amount of policy acquisition costs capitalized during the income statement period.
+ References
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