Life Policy And Investment Contract Reservess (Reserve In Addition To The Account Balance Based On Expected No-Lapse Guarantee Benefits And Expected Policy Assessments) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Liability for Future Policy Benefit, by Product Segment
Life policy and investment contract reserves	$ 2,779	$ 2,729
Life Policy Reserves
Liability for Future Policy Benefit, by Product Segment
Life policy and investment contract reserves	1,197	1,127
Life Policy Reserves | Ordinary/Traditional Life
Liability for Future Policy Benefit, by Product Segment
Life policy and investment contract reserves	1,149	1,080
Life Policy Reserves | Other Life Policy Reserves
Liability for Future Policy Benefit, by Product Segment
Life policy and investment contract reserves	48	47
Investment contract reserves
Liability for Future Policy Benefit, by Product Segment
Life policy and investment contract reserves	1,582	1,602
Investment contract reserves | Deferred Annuities
Liability for Future Policy Benefit, by Product Segment
Life policy and investment contract reserves	787	835
Investment contract reserves | Universal Life
Liability for Future Policy Benefit, by Product Segment
Life policy and investment contract reserves	632	601
Investment contract reserves | Structured Settlements
Liability for Future Policy Benefit, by Product Segment
Life policy and investment contract reserves	156	160
Investment contract reserves | Other Investment Contract Reserves
Liability for Future Policy Benefit, by Product Segment
Life policy and investment contract reserves	$ 7	$ 6