|**Life Policy and Investment Contract Reserves (Tables)** | 6 Months Ended                                                                                                                                                                                                                                                                                                                                                                                             
|--------------------------------------------------------- | -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
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|**Liability for Future Policy Benefits [Abstract]**       |                                                                                                                                                                                                                                                                                                                                                                                                            
|Reserve For Losses Loss Adjustment Expenses Table         | This table summarizes our life policy and investment contract reserves:(Dollars in millions)June 30, 2019December 31, 2018Life policy reserves:Ordinary/traditional life$1,187$1,149Other4948Subtotal1,2361,197Investment contract reserves:Deferred annuities771787Universal life633632Structured settlements152156Other67Subtotal1,5621,582Total life policy and investment contract reserves$2,798$2,779
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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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