| **Deferred Acquisition Costs - Deferred Policy Acquisition Costs and Asset Reconciliation (Detail) - USD ($) $ in Millions** | 3 Months Ended | 6 Months Ended |
|------------------------------------------------------------------------------------------------------------------------------|----------------|----------------|
||
| **Movement Analysis of Deferred Policy Acquisition Costs**                                                                   |           |           |   |   |
| Deferred policy acquisition costs asset, beginning of period                                                                 | $ 751          | $ 691          | $ 738 | $ 670 |
| Capitalized deferred policy acquisition costs                                                                                | 295            | 266            | 565 | 511 |
| Amortized deferred policy acquisition costs                                                                                  | (251)          | (236)          | (497) | (470) |
| Shadow deferred policy acquisition costs                                                                                     | (9)            | 7              | (20) | 17 |
| Deferred policy acquisition costs asset, end of period                                                                       | 786            | 728            | 786 | 728 |
| Consolidated Property and Casualty Insurance Entity                                                                          |           |           |   |   |
| **Movement Analysis of Deferred Policy Acquisition Costs**                                                                   |           |           |   |   |
| Deferred policy acquisition costs asset, beginning of period                                                                 | 485            | 446            | 464 | 438 |
| Capitalized deferred policy acquisition costs                                                                                | 280            | 251            | 534 | 483 |
| Amortized deferred policy acquisition costs                                                                                  | (239)          | (225)          | (472) | (449) |
| Deferred policy acquisition costs asset, end of period                                                                       | 526            | 472            | 526 | 472 |
| Life Insurance Segment                                                                                                       |           |           |   |   |
| **Movement Analysis of Deferred Policy Acquisition Costs**                                                                   |           |           |   |   |
| Deferred policy acquisition costs asset, beginning of period                                                                 | 266            | 245            | 274 | 232 |
| Capitalized deferred policy acquisition costs                                                                                | 15             | 15             | 31 | 28 |
| Amortized deferred policy acquisition costs                                                                                  | (12)           | (11)           | (25) | (21) |
| Shadow deferred policy acquisition costs                                                                                     | (9)            | 7              | (20) | 17 |
| Deferred policy acquisition costs asset, end of period                                                                       | $ 260          | $ 256          | $ 260 | $ 256 |

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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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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - 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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