| **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                                                                 | $ 728          | $ 678          | $ 670 | $ 637 |
| Capitalized deferred policy acquisition costs                                                                                | 244            | 236            | 755 | 724 |
| Deferred Policy Acquisition Costs, Amortization Expense                                                                      | (231)          | (237)          | (701) | (680) |
| Deferred Policy Acquisition Cost, Amortization Expense, Other                                                                | 2              | (1)            | 19 | (5) |
| Deferred policy acquisition costs asset, end of period                                                                       | 743            | 676            | 743 | 676 |
| Life Insurance Product Line [Member]                                                                                         |           |           |   |   |
| **Movement Analysis of Deferred Policy Acquisition Costs [Roll Forward]**                                                    |           |           |   |   |
| Deferred policy acquisition costs asset, beginning of period                                                                 | 256            | 230            | 232 | 229 |
| Capitalized deferred policy acquisition costs                                                                                | 15             | 13             | 43 | 38 |
| Deferred Policy Acquisition Costs, Amortization Expense                                                                      | (6)            | (17)           | (27) | (37) |
| Deferred Policy Acquisition Cost, Amortization Expense, Other                                                                | 2              | (1)            | 19 | (5) |
| Deferred policy acquisition costs asset, end of period                                                                       | 267            | 225            | 267 | 225 |
| Consolidated Property and Casualty Insurance Entity                                                                          |           |           |   |   |
| **Movement Analysis of Deferred Policy Acquisition Costs [Roll Forward]**                                                    |           |           |   |   |
| Deferred policy acquisition costs asset, beginning of period                                                                 | 472            | 448            | 438 | 408 |
| Capitalized deferred policy acquisition costs                                                                                | 229            | 223            | 712 | 686 |
| Deferred Policy Acquisition Costs, Amortization Expense                                                                      | (225)          | (220)          | (674) | (643) |
| Deferred policy acquisition costs asset, end of period                                                                       | $ 476          | $ 451          | $ 476 | $ 451 |

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|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of amortization expense (reversal of expense) for 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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