| **Fair Value Measurements - Fair Values of Deferred Annuities, Structured Settlements and Other Items (Detail) (USD $)In Millions, unless otherwise specified** | Mar. 31, 2013 | Dec. 31, 2012 |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------|---------------|---------------|
| **Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]**                                                                |          |          |
| Fair Value of life insurance liabilities                                                                                                                        | $ 1,133       | $ 1,138       |
| Deferred Annuities                                                                                                                                              |          |          |
| **Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]**                                                                |          |          |
| Fair Value of life insurance liabilities                                                                                                                        | 898           | 898           |
| Structured Settlements                                                                                                                                          |          |          |
| **Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]**                                                                |          |          |
| Fair Value of life insurance liabilities                                                                                                                        | 235           | 240           |
| 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                                                                                                                        | 235           | 240           |
| 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                                                                                                                        | 235           | 240           |
| Significant unobservable inputs (Level 3)                                                                                                                       |          |          |
| **Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]**                                                                |          |          |
| Fair Value of life insurance liabilities                                                                                                                        | 898           | 898           |
| 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                                                                                                                        | 898           | 898           |
| 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                                                                                                                                                                                                                 |
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| - Details**Name:**us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems**Namespace Prefix:**us-gaap_**Data Type:**xbrli:stringItemType**Balance Type:**na**Period Type:**duration |
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| - Definition
This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. The amount shown on an entity's books for liabilities related to investment contracts (guaranteed investment contract, annuities), net of any reductions or offsets.
+ 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=d3e32427-158581Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 14 -Article 7Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 97 -Paragraph 15 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.  This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.
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