Servicing Activities (Schedule of Total Serviced Automobile Loans Outstanding) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Automobile Serviced Assets [Line Items]
Contractually Specified Servicing Fees, Late Fees, and Ancillary Fees Earned in Exchange for Servicing Financial Assets	$ 18	$ 12	$ 49	$ 32
Automobile Loan [Member]
Automobile Serviced Assets [Line Items]
Contractually Specified Servicing Fees, Late Fees, and Ancillary Fees Earned in Exchange for Servicing Financial Assets	18	$ 12	49	$ 32
Servicing Asset	119,625		119,625		$ 119,808
Consumer Loan [Member] | On-Balance Sheet Loans [Member] | Automobile Loan [Member]
Automobile Serviced Assets [Line Items]
Servicing Asset	64,672		64,672		64,067
Commercial Loan [Member] | On-Balance Sheet Loans [Member] | Automobile Loan [Member]
Automobile Serviced Assets [Line Items]
Servicing Asset	36,036		36,036		34,895
Operating Leases [Member] | On-Balance Sheet Loans [Member] | Automobile Loan [Member]
Automobile Serviced Assets [Line Items]
Servicing Asset	12,497		12,497		15,965
Other Assets [Member] | On-Balance Sheet Loans [Member] | Automobile Loan [Member]
Automobile Serviced Assets [Line Items]
Servicing Asset	68		68		72
Securitizations [Member] | Off-Balance Sheet Loans [Member] | Automobile Loan [Member]
Automobile Serviced Assets [Line Items]
Servicing Asset	2,760		2,760		2,550
Whole-Loan Transactions [Member] | Off-Balance Sheet Loans [Member] | Automobile Loan [Member]
Automobile Serviced Assets [Line Items]
Servicing Asset	$ 3,592		$ 3,592		$ 2,259