| **Reinsurance (Tables)**                                                                               | 6 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: (Dollars in millions) Three months ended June 30, Six months ended June 30,  2015 2014 2015 2014Direct earned premiums $1,093 $1,048 $2,169 $2,067Assumed earned premiums 3 2 5 5Ceded earned premiums (37) (44) (74) (87)Earned premiums $1,059 $1,006 $2,100 $1,985                                                                            |
| 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:(Dollars in millions) Three months ended June 30, Six months ended June 30,  2015 2014 2015 2014Direct incurred loss and loss expenses $675 $716 $1,366 $1,393Assumed incurred loss and loss expenses 1 2 0 4Ceded incurred loss and loss expenses (22) (11) (23) (14)Incurred loss and loss expenses $654 $707 $1,343 $1,383          |
| Earned Life Insurance Premiums On Ceded Business                                                       | Our condensed consolidated statements of income include earned life insurance premiums on ceded business: (Dollars in millions) Three months ended June 30, Six months ended June 30,  2015 2014 2015 2014Direct earned premiums $68 $68 $133 $130Ceded earned premiums (16) (15) (28) (29)Earned premiums $52 $53 $105 $101                                                                                                                                                                                    |
| 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: (Dollars in millions) Three months ended June 30, Six months ended June 30,  2015 2014 2015 2014Direct contract holders' benefits incurred $72 $68 $144 $148Ceded contract holders' benefits incurred (14) (12) (26) (36)Contract holders' benefits incurred $58 $56 $118 $112                                                                                                    |

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Life Insurance Contract Holders' Benefits Incurred On Ceded Business
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