Securitizations and Variable Interest Entities (Schedule of Quantitative Information and Net Credit Losses about Securitized and Other Financial Assets Managed Together) (Details) - Consumer Automotive Industry Sector - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Derecognized Assets, Securitized or Asset-backed Financing Arrangement Assets and any Other Financial Assets Managed Together [Line Items]
Loans managed and securitized, principal amount outstanding	$ 379		$ 379		$ 624
Derecognized Assets, Securitized or Asset-backed Financing Arrangement Assets and any Other Financial Assets Managed Together, Delinquent Amount at End of Period	6		6		8
Derecognized Assets, Securitized or Asset-backed Financing Arrangement Assets and any Other Financial Assets Managed Together, Net Credit Losses During Period	0	$ 3	1	$ 5
Whole Loan Sales
Derecognized Assets, Securitized or Asset-backed Financing Arrangement Assets and any Other Financial Assets Managed Together [Line Items]
Loans managed and securitized, principal amount outstanding	103		103		207
Derecognized Assets, Securitized or Asset-backed Financing Arrangement Assets and any Other Financial Assets Managed Together, Delinquent Amount at End of Period	1		1		2
Derecognized Assets, Securitized or Asset-backed Financing Arrangement Assets and any Other Financial Assets Managed Together, Net Credit Losses During Period	0	1	0	1
Off-balance sheet variable interest entities
Derecognized Assets, Securitized or Asset-backed Financing Arrangement Assets and any Other Financial Assets Managed Together [Line Items]
Loans managed and securitized, principal amount outstanding	276		276		417
Derecognized Assets, Securitized or Asset-backed Financing Arrangement Assets and any Other Financial Assets Managed Together, Delinquent Amount at End of Period	5		5		$ 6
Derecognized Assets, Securitized or Asset-backed Financing Arrangement Assets and any Other Financial Assets Managed Together, Net Credit Losses During Period	$ 0	$ 2	$ 1	$ 4