| **Reinsurance (Tables)**                                                                               | 3 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                               |
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| **Reinsurance Disclosures [Abstract]**                                                                 |                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
| Earned Consolidated Property Casualty Insurance Premiums On Assumed And Ceded Business                 | Our condensed consolidated statements of income include earned consolidated property casualty insurance premiums on assumed and ceded business: (In millions) Three months ended March 31,  2013 2012Direct earned premiums $935 $839Assumed earned premiums 2 3Ceded earned premiums (48) (44)Net earned premiums $889 $798                                                                                |
| Incurred Consolidated Property Casualty Insurance Loss And Loss Expenses On Assumed And Ceded Business | Our condensed consolidated statements of income include incurred consolidated property casualty insurance loss and loss expenses on assumed and ceded business: (In millions) Three months ended March 31,  2013 2012Direct incurred loss and loss expenses $535 $536Assumed incurred loss and loss expenses 2 5Ceded incurred loss and loss expenses (13) (2)Net incurred loss and loss expenses $524 $539 |
| Earned Life Insurance Premiums On Ceded Business                                                       | Our condensed consolidated statements of income include earned life insurance premiums on ceded business: (In millions) Three months ended March 31,  2013 2012Direct earned premiums $56 $54Assumed earned premiums — —Ceded earned premiums (14) (13)Net earned premiums $42 $41                                                                                                         |
| Life Insurance Contract Holders' Benefits Incurred On Ceded Business                                   | Our condensed consolidated statements of income include life insurance contract holders’ benefits incurred on ceded business: (In millions) Three months ended March 31,  2013 2012Direct contract holders' benefits incurred $64 $53Assumed contract holders' benefits incurred — —Ceded contract holders' benefits incurred (20) (10)Net incurred loss and loss expenses $44 $43   |

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Life Insurance Contract Holders' Benefits Incurred On Ceded Business
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Life insurance premiums earned on assumed and ceded business.
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No definition available.
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