Securitizations and Variable Interest Entities (Schedule of Variable Interest Entities) (Details) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Variable Interest Entity [Line Items]
Total consoldiated involvement with VIEs	$ 39,646	$ 44,940
Assets of nonconsolidated variable interest entities	3,240	3,034
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	3,820	3,527
Other assets	6,307	6,321
Consumer Portfolio Segment [Member] | Automobile Loan [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Assets	23,608	27,967
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets	24	0
Assets of nonconsolidated variable interest entities	3,240	3,034
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	3,264	3,034
Continuing Involvement with Continued to be Recognized Transferred Financial Assets, Amount Outstanding	10,000	10,600
Commercial Portfolio Segment [Member] | Automobile Loan [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Assets	15,746	16,763
Commercial Portfolio Segment [Member] | Other Financing Receivables [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets	268	210
Assets of nonconsolidated variable interest entities	0	0
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	556	493
Other assets	276	222
Accrued Liabilities	$ 8	$ 12