Segment Reporting - Operations Reporting by Revenue (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Segment Reporting Information [Line Items]
Total revenue	$ 2,075	$ 1,354
Operating expenses, including leased vehicle expenses	1,227	633
Provision for loan losses	196	155
Interest expense	463	380
Equity income	36	28
Income before income taxes	225	214
Operating Segments [Member] | North America Segment [Member]
Segment Reporting Information [Line Items]
Total revenue	1,688	906
Operating expenses, including leased vehicle expenses	1,089	487
Provision for loan losses	177	118
Interest expense	305	165
Equity income	0	0
Income before income taxes	117	136
Operating Segments [Member] | International Segment [Member]
Segment Reporting Information [Line Items]
Total revenue	387	448
Operating expenses, including leased vehicle expenses	138	146
Provision for loan losses	19	37
Interest expense	157	206
Equity income	36	28
Income before income taxes	109	87
Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Total revenue	(1)	7
Operating expenses, including leased vehicle expenses	0	0
Provision for loan losses	0	0
Interest expense	0	16
Equity income	0	0
Income before income taxes	(1)	(9)
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Total revenue	1	(7)
Operating expenses, including leased vehicle expenses	0	0
Provision for loan losses	0	0
Interest expense	1	(7)
Equity income	0	0
Income before income taxes	$ 0	$ 0