| **Deferred Acquisition Costs - Deferred Policy Acquisition Costs and Asset Reconciliation (Detail) - USD ($) $ in Millions** | 3 Months Ended |
|------------------------------------------------------------------------------------------------------------------------------|----------------|
||
| **Movement Analysis of Deferred Policy Acquisition Costs [Roll Forward]**                                                    |           |   |
| Deferred policy acquisition costs asset, beginning of period                                                                 | $ 637          | $ 616 |
| Capitalized deferred policy acquisition costs                                                                                | 239            | 222 |
| Deferred Policy Acquisition Cost, Amortization Expense                                                                       | (214)          | (212) |
| Deferred Policy Acquisition Cost, Amortization Expense, Other                                                                | (2)            | (8) |
| Deferred policy acquisition costs asset, end of period                                                                       | 660            | 618 |
| Life Insurance Product Line [Member]                                                                                         |           |   |
| **Movement Analysis of Deferred Policy Acquisition Costs [Roll Forward]**                                                    |           |   |
| Deferred policy acquisition costs asset, beginning of period                                                                 | 229            | 228 |
| Capitalized deferred policy acquisition costs                                                                                | 13             | 12 |
| Deferred Policy Acquisition Cost, Amortization Expense                                                                       | (8)            | (11) |
| Deferred Policy Acquisition Cost, Amortization Expense, Other                                                                | (2)            | (8) |
| Deferred policy acquisition costs asset, end of period                                                                       | 232            | 221 |
| Consolidated Property and Casualty Insurance Entity                                                                          |           |   |
| **Movement Analysis of Deferred Policy Acquisition Costs [Roll Forward]**                                                    |           |   |
| Deferred policy acquisition costs asset, beginning of period                                                                 | 408            | 388 |
| Capitalized deferred policy acquisition costs                                                                                | 226            | 210 |
| Deferred Policy Acquisition Cost, Amortization Expense                                                                       | (206)          | (201) |
| Deferred policy acquisition costs asset, end of period                                                                       | $ 428          | $ 397 |

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|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of expense related to deferred policy acquisition costs.
+ References
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|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of other increase (decrease) to amortization expense of deferred policy acquisition cost (DAC).
+ References
No definition available.
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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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| - 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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