| **Fair Value Measurements - Fair Values of Deferred Annuities, Structured Settlements and Other Items (Detail) - USD ($) $ in Millions** | Jun. 30, 2017 | Dec. 31, 2016 |
|------------------------------------------------------------------------------------------------------------------------------------------|---------------|---------------|
| **Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]**                                         |          |          |
| Fair Value of life insurance liabilities                                                                                                 | $ 1,052       | $ 1,045       |
| Deferred annuities                                                                                                                       |          |          |
| **Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]**                                         |          |          |
| Fair Value of life insurance liabilities                                                                                                 | 846           | 839           |
| Structured Settlements                                                                                                                   |          |          |
| **Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]**                                         |          |          |
| Fair Value of life insurance liabilities                                                                                                 | 206           | 206           |
| Quoted prices in active markets for identical assets (Level 1)                                                                           |          |          |
| **Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]**                                         |          |          |
| Fair Value of life insurance liabilities                                                                                                 | 0             | 0             |
| Quoted prices in active markets for identical assets (Level 1) | Deferred annuities                                                      |          |          |
| **Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]**                                         |          |          |
| Fair Value of life insurance liabilities                                                                                                 | 0             | 0             |
| Quoted prices in active markets for identical assets (Level 1) | Structured Settlements                                                  |          |          |
| **Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]**                                         |          |          |
| Fair Value of life insurance liabilities                                                                                                 | 0             | 0             |
| Significant other observable inputs (Level 2)                                                                                            |          |          |
| **Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]**                                         |          |          |
| Fair Value of life insurance liabilities                                                                                                 | 206           | 206           |
| Significant other observable inputs (Level 2) | Deferred annuities                                                                       |          |          |
| **Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]**                                         |          |          |
| Fair Value of life insurance liabilities                                                                                                 | 0             | 0             |
| Significant other observable inputs (Level 2) | Structured Settlements                                                                   |          |          |
| **Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]**                                         |          |          |
| Fair Value of life insurance liabilities                                                                                                 | 206           | 206           |
| Significant unobservable inputs (Level 3)                                                                                                |          |          |
| **Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]**                                         |          |          |
| Fair Value of life insurance liabilities                                                                                                 | 846           | 839           |
| Significant unobservable inputs (Level 3) | Deferred annuities                                                                           |          |          |
| **Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]**                                         |          |          |
| Fair Value of life insurance liabilities                                                                                                 | 846           | 839           |
| Significant unobservable inputs (Level 3) | Structured Settlements                                                                       |          |          |
| **Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]**                                         |          |          |
| Fair Value of life insurance liabilities                                                                                                 | $ 0           | $ 0           |

| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.
+ References
No definition available.
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| - Definition
Fair value portion of liability related to investment contracts for example, but not limited to, guaranteed investment contract or annuities.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 825 -Section 25 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6487514&loc=d3e32427-158581
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