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, 2019	Dec. 31, 2018
Liability for Future Policy Benefit, by Product Segment
Life policy and investment contract reserves	$ 2,835	$ 2,779
Life Policy Reserves
Liability for Future Policy Benefit, by Product Segment
Life policy and investment contract reserves	1,276	1,197
Life Policy Reserves | Ordinary/Traditional Life
Liability for Future Policy Benefit, by Product Segment
Life policy and investment contract reserves	1,226	1,149
Life Policy Reserves | Other Life Policy Reserves
Liability for Future Policy Benefit, by Product Segment
Life policy and investment contract reserves	50	48
Investment contract reserves
Liability for Future Policy Benefit, by Product Segment
Life policy and investment contract reserves	1,559	1,582
Investment contract reserves | Deferred Annuities
Liability for Future Policy Benefit, by Product Segment
Life policy and investment contract reserves	760	787
Investment contract reserves | Universal Life
Liability for Future Policy Benefit, by Product Segment
Life policy and investment contract reserves	640	632
Investment contract reserves | Structured Settlements
Liability for Future Policy Benefit, by Product Segment
Life policy and investment contract reserves	151	156
Investment contract reserves | Other Investment Contract Reserves
Liability for Future Policy Benefit, by Product Segment
Life policy and investment contract reserves	$ 8	$ 7