Finance Receivables and Loans, Net Finance Receivables and Loans, Net (Schedule of Purchases of Financing Receivables and Loans) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Significant Purchases	$ 1,266	$ 467	$ 3,081	$ 2,855
Consumer Portfolio Segment [Member] | Automobile Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Significant Purchases	83	0	762	0
Consumer Portfolio Segment [Member] | Residential Mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Significant Purchases	$ 1,183	$ 467	$ 2,319	$ 2,855