|**Life Policy and Investment Contract Reserves (Tables)**              | 3 Months Ended                                                                                                                                                                                                                                                                                                                                                                                              
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|**Liability for Future Policy Benefit, before Reinsurance [Abstract]** |                                                                                                                                                                                                                                                                                                                                                                                                             
|Reserve For Losses Loss Adjustment Expenses Table                      | This table summarizes our life policy and investment contract reserves:(Dollars in millions)March 31, 2020December 31, 2019Life policy reserves:Ordinary/traditional life$1,245$1,226Other5050Subtotal1,2951,276Investment contract reserves:Deferred annuities754760Universal life653640Structured settlements151151Other88Subtotal1,5661,559Total life policy and investment contract reserves$2,861$2,835
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|(Dollars in millions)                                                  |                                                                                                                                                                                                                                                                                                                                                                                                             
|Life policy reserves:                                                  |                                                                                                                                                                                                                                                                                                                                                                                                             
|Ordinary/traditional life                                              |                                                                                                                                                                                                                                                                                                                                                                                                             
|Other                                                                  |                                                                                                                                                                                                                                                                                                                                                                                                             
|Subtotal                                                               |                                                                                                                                                                                                                                                                                                                                                                                                             
|Investment contract reserves:                                          |                                                                                                                                                                                                                                                                                                                                                                                                             
|Deferred annuities                                                     |                                                                                                                                                                                                                                                                                                                                                                                                             
|Universal life                                                         |                                                                                                                                                                                                                                                                                                                                                                                                             
|Structured settlements                                                 |                                                                                                                                                                                                                                                                                                                                                                                                             
|Other                                                                  |                                                                                                                                                                                                                                                                                                                                                                                                             
|Subtotal                                                               |                                                                                                                                                                                                                                                                                                                                                                                                             
|Total life policy and investment contract reserves                     |                                                                                                                                                                                                                                                                                                                                                                                                             
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