Segment Reporting - Operations Reporting by Revenue (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Segment Reporting Information [Line Items]
Total revenue	$ 2,292	$ 1,515	$ 4,367	$ 2,869
Operating expenses	343	319	677	625
Leased vehicle expenses	1,068	467	1,961	794
Provision for loan losses	151	141	347	296
Interest expense	501	391	964	771
Equity income	37	28	73	56
Income before income taxes	266	225	491	439
Operating Segments [Member] | North America Segment [Member]
Segment Reporting Information [Line Items]
Total revenue	1,886	1,085	3,574	1,991
Operating expenses	215	184	416	345
Leased vehicle expenses	1,061	464	1,949	790
Provision for loan losses	125	111	302	229
Interest expense	337	193	642	358
Equity income	0	0	0	0
Income before income taxes	148	133	265	269
Operating Segments [Member] | International Segment [Member]
Segment Reporting Information [Line Items]
Total revenue	406	430	793	878
Operating expenses	128	135	261	280
Leased vehicle expenses	7	3	12	4
Provision for loan losses	26	30	45	67
Interest expense	164	183	321	389
Equity income	37	28	73	56
Income before income taxes	118	107	227	194
Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Total revenue	0	4	(1)	11
Operating expenses	0	0	0	0
Leased vehicle expenses	0	0	0	0
Provision for loan losses	0	0	0	0
Interest expense	0	19	0	35
Equity income	0	0	0	0
Income before income taxes	0	(15)	(1)	(24)
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Total revenue	0	(4)	1	(11)
Operating expenses	0	0	0	0
Leased vehicle expenses	0	0	0	0
Provision for loan losses	0	0	0	0
Interest expense	0	(4)	1	(11)
Equity income	0	0	0	0
Income before income taxes	$ 0	$ 0	$ 0	$ 0