|**Other Intangible Assets (Tables)**                         | 6 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           
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|**Intangible Assets, Gross (Excluding Goodwill) [Abstract]** |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          
|Schedule of Other Intangible Assets                          | Other intangible assets are presented in the following table.June 30, 2014December 31, 2013(In millions)Economic Useful LifeGross Carrying AmountAccumulated AmortizationGross Carrying AmountAccumulated AmortizationFinite-lived intangible assets:Value of business acquired1 - 4 years$66$66$64$63Trade name8 years8282Distribution channel15 years142131Total finite-lived intangible assets88708566Indefinite-lived intangible assets:Syndicate capacity6058Agency force1616Total indefinite-lived intangible assets7674Total other intangible assets$164$70$159$66
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|(In millions)                                                | Economic Useful Life                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     
|Finite-lived intangible assets:                              |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          
|Value of business acquired                                   | 1 - 4 years                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              
|Trade name                                                   | 8 years                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  
|Distribution channel                                         | 15 years                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 
|Total finite-lived intangible assets                         |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          
|Indefinite-lived intangible assets:                          |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          
|Syndicate capacity                                           |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          
|Agency force                                                 |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          
|Total indefinite-lived intangible assets                     |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          
|Total other intangible assets                                |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          

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