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	9 Months Ended
	Sep. 30, 2019	Sep. 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	$ 18	$ 13
Cash flows between transferor and transferee, servicing fees	8	14
Cash flows between transferor and transferee, disbursement for repurchases during the period	(2)	(3)
Cash Flows Between Transferor and Transferee, Proceeds from New Transfers		24
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 Flows Between Transferor and Transferee, Proceeds from New Transfers		0
Cash Flow Between Transferee and Transferor Representations And Warranties Obligations		$ 2