Finance Receivables - Credit Quality (Details) - North America Segment [Member] - Automobile Loan [Member] - Retail Finance Receivables [Member] - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016
Financing Receivable, Recorded Investment [Line Items]
Finance receivables, net of fees	$ 26,030	$ 21,786
Finance receivables credit indicator, Percent	100.00%	100.00%
Prime - FICO Score 680 and greater [Member]
Financing Receivable, Recorded Investment [Line Items]
Finance receivables, net of fees	$ 11,497	$ 7,923
Finance receivables credit indicator, Percent	44.20%	36.40%
Near-prime - FICO Score 620 to 679 [Member]
Financing Receivable, Recorded Investment [Line Items]
Finance receivables, net of fees	$ 3,973	$ 3,468
Finance receivables credit indicator, Percent	15.20%	15.90%
Sub-prime - FICO Score less than 620 [Member]
Financing Receivable, Recorded Investment [Line Items]
Finance receivables, net of fees	$ 10,560	$ 10,395
Finance receivables credit indicator, Percent	40.60%	47.70%