Investmenst (Changes In Allowance For Credit Losses On Mortgage Loans On Real Estate) (Details) $ in Millions	3 Months Ended
	Mar. 31, 2020 USD ($)
Balance as of beginning-of-year, prior to adoption of ASU 2016-13	$ 2
Additions from provision for credit loss expense	71
Balance as of end-of-period	161
Accrued interest receivable excluded from credit losses	50
Cumulative Effect, Period of Adoption, Adjustment [Member]
Balance as of end-of-period	88
Commercial [Member]
Additions from provision for credit loss expense	64
Balance as of end-of-period	126
Commercial [Member] | Cumulative Effect, Period of Adoption, Adjustment [Member]
Balance as of end-of-period	62
Residential [Member]
Balance as of beginning-of-year, prior to adoption of ASU 2016-13	2
Additions from provision for credit loss expense	7
Balance as of end-of-period	35
Residential [Member] | Cumulative Effect, Period of Adoption, Adjustment [Member]
Balance as of end-of-period	$ 26