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, 2020	Dec. 31, 2019
Liability for Future Policy Benefit, by Product Segment
Life policy and investment contract reserves	$ 2,915	$ 2,835
Life Policy Reserves
Liability for Future Policy Benefit, by Product Segment
Life policy and investment contract reserves	1,353	1,276
Life Policy Reserves | Ordinary/Traditional Life
Liability for Future Policy Benefit, by Product Segment
Life policy and investment contract reserves	1,301	1,226
Life Policy Reserves | Other Life Policy Reserves
Liability for Future Policy Benefit, by Product Segment
Life policy and investment contract reserves	52	50
Investment contract reserves
Liability for Future Policy Benefit, by Product Segment
Life policy and investment contract reserves	1,562	1,559
Investment contract reserves | Deferred Annuity
Liability for Future Policy Benefit, by Product Segment
Life policy and investment contract reserves	761	760
Investment contract reserves | Universal Life
Liability for Future Policy Benefit, by Product Segment
Life policy and investment contract reserves	647	640
Investment contract reserves | Structured Settlement Annuity
Liability for Future Policy Benefit, by Product Segment
Life policy and investment contract reserves	145	151
Investment contract reserves | Other Investment Contract Reserves
Liability for Future Policy Benefit, by Product Segment
Life policy and investment contract reserves	$ 9	$ 8