Securitizations and Variable Interest Entities (Schedule of Cash Flow Received from and Paid to Nonconsolidated Securitization Entities) (Details) - Off-balance sheet variable interest entities - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Consumer Automotive Industry Sector
Cash Flow Received and Paid to Nonconsolidated Securitization Entities [Line Items]
Cash flows received on retained interests in securitization entities	$ 13	$ 9
Cash flows between transferor and transferee, servicing fees	6	10
Cash flows between transferor and transferee, disbursement for repurchases during the period	(1)	(2)
Cash Flow Between Transferee and Transferor Representations And Warranties Obligations		0
Consumer Mortgage Industry Sector
Cash Flow Received and Paid to Nonconsolidated Securitization Entities [Line Items]
Cash flows received on retained interests in securitization entities	0	0
Cash flows between transferor and transferee, servicing fees	0	0
Cash flows between transferor and transferee, disbursement for repurchases during the period	$ 0	0
Cash Flow Between Transferee and Transferor Representations And Warranties Obligations		$ 2