| **Deferred Acquisition Costs - Deferred Policy Acquisition Costs and Asset Reconciliation (Detail) - USD ($) $ in Millions** | 3 Months Ended | 9 Months Ended |
|------------------------------------------------------------------------------------------------------------------------------|----------------|----------------|
||
| **Movement Analysis of Deferred Policy Acquisition Costs [Roll Forward]**                                                    |           |           |   |   |
| Deferred policy acquisition costs asset, beginning of period                                                                 | $ 624          | $ 600          | $ 616 | $ 578 |
| Capitalized deferred policy acquisition costs                                                                                | 227            | 212            | 679 | 640 |
| Deferred Policy Acquisition Cost, Amortization Expense                                                                       | (222)          | (207)          | (648) | (620) |
| Deferred Policy Acquisition Cost, Amortization Expense, Other                                                                | (2)            | 4              | (20) | 11 |
| Deferred policy acquisition costs asset, end of period                                                                       | 627            | 609            | 627 | 609 |
| Life Insurance Product Line [Member]                                                                                         |           |           |   |   |
| **Movement Analysis of Deferred Policy Acquisition Costs [Roll Forward]**                                                    |           |           |   |   |
| Deferred policy acquisition costs asset, beginning of period                                                                 | 212            | 210            | 228 | 199 |
| Capitalized deferred policy acquisition costs                                                                                | 11             | 11             | 35 | 34 |
| Deferred Policy Acquisition Cost, Amortization Expense                                                                       | (15)           | (10)           | (37) | (29) |
| Deferred Policy Acquisition Cost, Amortization Expense, Other                                                                | (2)            | 4              | (20) | 11 |
| Deferred policy acquisition costs asset, end of period                                                                       | 206            | 215            | 206 | 215 |
| Consolidated Property and Casualty Insurance Entity                                                                          |           |           |   |   |
| **Movement Analysis of Deferred Policy Acquisition Costs [Roll Forward]**                                                    |           |           |   |   |
| Deferred policy acquisition costs asset, beginning of period                                                                 | 412            | 390            | 388 | 379 |
| Capitalized deferred policy acquisition costs                                                                                | 216            | 201            | 644 | 606 |
| Deferred Policy Acquisition Cost, Amortization Expense                                                                       | (207)          | (197)          | (611) | (591) |
| Deferred policy acquisition costs asset, end of period                                                                       | $ 421          | $ 394          | $ 421 | $ 394 |

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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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