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 ($)	Sep. 30, 2020 USD ($)
Schedule of Investments [Line Items]
Balance as of beginning-of-period	$ 271	$ 2
Additions from provision for credit loss expense		182
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	(70)	(70)
Balance as of end-of-period	201	201
Changes in economic assumptions increasing provision	(70)	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]
Schedule of Investments [Line Items]
Balance as of beginning-of-period		87
Unfunded Loan Commitment [Member]
Schedule of Investments [Line Items]
Changes in economic assumptions increasing provision	0	1
Commercial [Member]
Schedule of Investments [Line Items]
Balance as of beginning-of-period	234
Additions from provision for credit loss expense		173
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	(63)	(63)
Balance as of end-of-period	171	171
Commercial [Member] | Cumulative Effect, Period of Adoption, Adjustment [Member]
Schedule of Investments [Line Items]
Balance as of beginning-of-period		61
Residential [Member]
Schedule of Investments [Line Items]
Balance as of beginning-of-period	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]
Schedule of Investments [Line Items]
Balance as of beginning-of-period		$ 26