Investmenst (Changes In Allowance For Credit Losses On Mortgage Loans On Real Estate) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Balance as of beginning-of-year	$ 204	$ 2
Additions from provision for credit loss expense	6	71
Additions (reductions) for mortgage loans on real estate for which credit losses were previously recognized	(26)
Balance as of end-of-year	184	161
Changes in economic assumptions increasing provision	(20)	71
Accrued interest receivable excluded from credit losses	51	50
Unfunded Loan Commitment [Member]
Additions (reductions) for mortgage loans on real estate for which credit losses were previously recognized	4
Changes in economic assumptions increasing provision		1
Commercial [Member]
Balance as of beginning-of-year	187
Additions from provision for credit loss expense	4	64
Additions (reductions) for mortgage loans on real estate for which credit losses were previously recognized	(19)
Balance as of end-of-year	172	126
Residential [Member]
Balance as of beginning-of-year	17	2
Additions from provision for credit loss expense	2	7
Additions (reductions) for mortgage loans on real estate for which credit losses were previously recognized	(7)
Balance as of end-of-year	$ 12	35
Cumulative Effect, Period of Adoption, Adjustment [Member]
Balance as of end-of-year		88
Cumulative Effect, Period of Adoption, Adjustment [Member] | Commercial [Member]
Balance as of end-of-year		62
Cumulative Effect, Period of Adoption, Adjustment [Member] | Residential [Member]
Balance as of end-of-year		$ 26