Finance Receivables - Finance Receivables, net (Details) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015	Sep. 30, 2015	Dec. 31, 2014
Accounts, Notes, Loans and Financing Receivable [Line Items]
Finance receivables, net	$ 41,132	$ 36,781
Fair value of finance receivables	41,530	36,937
Automobile Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Direct-financing leases	1,300	1,100
Deferred income	200	179
Automobile Loan [Member] | Retail Finance Receivables [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Collectively evaluated for impairment, net of fees	30,408	27,512
Individually evaluated for impairment, net of fees	1,838	1,612
Total finance receivables	32,246	29,124	$ 27,987	$ 25,623
Less: allowance for loan losses - collective	(566)	(515)
Less: allowance for loan losses - specific	(256)	(220)
Total finance receivables, net	31,424	28,389
Automobile Loan [Member] | Commercial Finance Receivables [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Collectively evaluated for impairment, net of fees	9,704	8,357
Individually evaluated for impairment, net of fees	56	82
Total finance receivables	9,760	8,439
Less: allowance for loan losses - collective	(46)	(38)
Less: allowance for loan losses - specific	(6)	(9)
Total finance receivables, net	$ 9,708	$ 8,392