Investmenst (Changes In Allowance For Credit Losses On Mortgage Loans On Real Estate) (Details) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2020 USD ($)	Sep. 30, 2020 USD ($)
Balance as of beginning-of-year, prior to adoption of ASU 2016-13	$ 273	$ 2
Additions from provision for credit loss expense		183
Additions from purchases of PCD mortgage loans on real estate
Additions (reductions) for mortgage loans on real estate for which credit losses were previously recognized	(71)	(71)
Balance as of end-of-period	202	202
Changes in economic assumptions increasing provision	(71)	112
Loss on disposal of mortgage loans on real estate	0	1
Accrued interest receivable excluded from credit losses	50	50
Cumulative Effect, Period of Adoption, Adjustment [Member]
Balance as of end-of-period	88	88
Unfunded Loan Commitment [Member]
Additions (reductions) for mortgage loans on real estate for which credit losses were previously recognized	0
Changes in economic assumptions increasing provision		1
Commercial [Member]
Balance as of beginning-of-year, prior to adoption of ASU 2016-13	236
Additions from provision for credit loss expense		174
Additions from purchases of PCD mortgage loans on real estate
Additions (reductions) for mortgage loans on real estate for which credit losses were previously recognized	(64)	(64)
Balance as of end-of-period	172	172
Commercial [Member] | Cumulative Effect, Period of Adoption, Adjustment [Member]
Balance as of end-of-period	62	62
Residential [Member]
Balance as of beginning-of-year, prior to adoption of ASU 2016-13	37	2
Additions from provision for credit loss expense		9
Additions from purchases of PCD mortgage loans on real estate
Additions (reductions) for mortgage loans on real estate for which credit losses were previously recognized	(7)	(7)
Balance as of end-of-period	30	30
Residential [Member] | Cumulative Effect, Period of Adoption, Adjustment [Member]
Balance as of end-of-period	$ 26	$ 26