Finance Receivables - Credit Quality (Details) - North America Segment [Member] - Automobile Loan [Member] - Retail Finance Receivables [Member] - USD ($) $ in Millions	Jun. 30, 2016	Dec. 31, 2015
Financing Receivable, Recorded Investment [Line Items]
Finance receivables, net of fees	$ 19,429	$ 18,148
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	$ 5,650	$ 4,418
Finance receivables credit indicator, Percent	29.10%	24.40%
FICO Score, 620 to 679 [Member]
Financing Receivable, Recorded Investment [Line Items]
Finance receivables, net of fees	$ 3,116	$ 2,890
Finance receivables credit indicator, Percent	16.00%	15.90%
FICO Score, Less than 620 [Member]
Financing Receivable, Recorded Investment [Line Items]
Finance receivables, net of fees	$ 10,663	$ 10,840
Finance receivables credit indicator, Percent	54.90%	59.70%