Finance Receivables - Finance Receivables, net (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Finance receivables, net	$ 46,910	$ 43,190
Fair value of finance receivables	46,722	43,140
Commercial Finance Receivables [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total finance receivables	11,812	11,123
Automobile Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Direct-financing leases	1,600	1,300
Deferred income	199	191
Automobile Loan [Member] | Retail Finance Receivables [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Collectively evaluated for impairment, net of fees	34,047	30,989
Individually evaluated for impairment, net of fees	1,957	1,921
Total finance receivables	36,004	32,910
Less: allowance for loan losses - collective	(568)	(517)
Less: allowance for loan losses - specific	(284)	(276)
Total finance receivables, net	35,152	32,117
Automobile Loan [Member] | Commercial Finance Receivables [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Collectively evaluated for impairment, net of fees	11,725	11,053
Individually evaluated for impairment, net of fees	87	70
Total finance receivables	11,812	11,123
Less: allowance for loan losses - collective	(46)	(43)
Less: allowance for loan losses - specific	(8)	(7)
Total finance receivables, net	$ 11,758	$ 11,073