Securitizations and Variable Interest Entities Securitizations and Variable Interest Entities (Affordable Housing Investments) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Securitizations And Variable Interest Entities [Abstract]
Affordable Housing Tax Credits and Other Tax Benefits, Amount	$ 86	$ 61	$ 43
Amortization Method Qualified Affordable Housing Project Investments, Amortization	72	51	44
Affordable Housing Project Investment, Write-down, Amount	0	0	$ 0
Amortization Method Qualified Affordable Housing Project Investments	830	649
Qualified Affordable Housing Project Investments, Commitment	$ 372	$ 319