Finance Receivables - Credit Quality (Details) - North America Segment [Member] - Automobile Loan [Member] - Retail Finance Receivables [Member] - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Financing Receivable, Recorded Investment [Line Items]
Finance receivables, net of fees	$ 24,354	$ 21,786
Finance receivables credit indicator, Percent	100.00%	100.00%
FICO Score 680 and greater [Member]
Financing Receivable, Recorded Investment [Line Items]
Finance receivables, net of fees	$ 10,062	$ 7,923
Finance receivables credit indicator, Percent	41.30%	36.40%
FICO Score 620 to 679 [Member]
Financing Receivable, Recorded Investment [Line Items]
Finance receivables, net of fees	$ 3,742	$ 3,468
Finance receivables credit indicator, Percent	15.40%	15.90%
FICO Score less than 620 [Member]
Financing Receivable, Recorded Investment [Line Items]
Finance receivables, net of fees	$ 10,550	$ 10,395
Finance receivables credit indicator, Percent	43.30%	47.70%