Securitizations and Variable Interest Entities (Schedule of Cash Flow Received from and Paid to Nonconsolidated Securitization Entities) (Details) - Consumer Portfolio Segment [Member] - Automobile Loan [Member] - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Cash Flow Received and Paid to Nonconsolidated Securitization Entities [Line Items]
Cash Flows Between Transferor and Transferee, Proceeds from New Transfers	$ 1,187	$ 1,604
Cash Flows Between Transferor and Transferee, Purchases of Previously Transferred Financial Assets	(491)
Cash Flows Between Transferor and Transferee, Servicing Fees	18	17
Cash Flows Between Transferor and Transferee, Beneficial Interest	10
Cash Flows Between Transferor and Transferee, Receipts on Transferor's Interest in Transferred Financial Assets, Other	$ 4	$ 5