|**Schedule V. Valuation and Qualifying Accounts** | 12 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     
|------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
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|**Valuation and Qualifying Accounts [Abstract]**  |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     
|Schedule V. Valuation and Qualifying Accounts     | SCHEDULE V. VALUATION AND QUALIFYING ACCOUNTS(In millions)Balance at Beginning of PeriodCharged to Costs and ExpensesCharged to Other Accounts (a)DeductionsBalance at End of PeriodYear ended December 31, 2012Deducted from assets:Allowance for doubtful accounts:Insurance and reinsurance receivables$203$(23)$5$(11)$174Year ended December 31, 2011Deducted from assets:Allowance for doubtful accounts:Insurance and reinsurance receivables$285$(55)$—$(27)$203Year ended December 31, 2010Deducted from assets:Allowance for doubtful accounts:Insurance and reinsurance receivables$553$(232)$(1)$(35)$285(a)    Amount includes effects of foreign currency translation.
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|                                                  |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     
|(In millions)                                     | Balance at Beginning of Period                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      
|Year ended December 31, 2012                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     
|Deducted from assets:                             |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     
|Allowance for doubtful accounts:                  |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     
|Insurance and reinsurance receivables             | $                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   
|Year ended December 31, 2011                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     
|Deducted from assets:                             |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     
|Allowance for doubtful accounts:                  |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     
|Insurance and reinsurance receivables             | $                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   
|Year ended December 31, 2010                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     
|Deducted from assets:                             |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     
|Allowance for doubtful accounts:                  |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     
|Insurance and reinsurance receivables             | $                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   

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