Guarantor Condensed Consolidating Financial Statements Guarantor Income Statements (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Condensed Income Statements, Captions [Line Items]
Finance charge income	$ 818	$ 854
Leased vehicle income	1,184	431
Other income	73	69
Total revenue	2,075	1,354
Salaries and benefits	193	165
Other operating expenses	141	141
Total operating expenses	334	306
Leased vehicle expenses	893	327
Provision for loan losses	196	155
Interest expense	463	380
Total costs and expenses	1,886	1,168
Equity income	36	28
Income before income taxes	225	214
Income tax (benefit) provision	61	64
Net income	164	150
Comprehensive income (loss)	316	(196)
Parent Company [Member]
Condensed Income Statements, Captions [Line Items]
Finance charge income	0	0
Leased vehicle income	0	0
Other income	(1)	7
Total revenue	(1)	7
Salaries and benefits	0	0
Other operating expenses	(4)	54
Total operating expenses	(4)	54
Leased vehicle expenses	0	0
Provision for loan losses	0	0
Interest expense	176	94
Total costs and expenses	172	148
Equity income	255	238
Income before income taxes	82	97
Income tax (benefit) provision	(82)	(53)
Net income	164	150
Comprehensive income (loss)	316	(196)
Guarantor [Member]
Condensed Income Statements, Captions [Line Items]
Finance charge income	99	80
Leased vehicle income	0	0
Other income	205	108
Total revenue	304	188
Salaries and benefits	135	89
Other operating expenses	68	(3)
Total operating expenses	203	86
Leased vehicle expenses	0	0
Provision for loan losses	103	74
Interest expense	(30)	(2)
Total costs and expenses	276	158
Equity income	168	129
Income before income taxes	196	159
Income tax (benefit) provision	12	11
Net income	184	148
Comprehensive income (loss)	223	90
Non-Guarantors [Member]
Condensed Income Statements, Captions [Line Items]
Finance charge income	719	774
Leased vehicle income	1,184	431
Other income	15	45
Total revenue	1,918	1,250
Salaries and benefits	58	76
Other operating expenses	170	154
Total operating expenses	228	230
Leased vehicle expenses	893	327
Provision for loan losses	93	81
Interest expense	370	315
Total costs and expenses	1,584	953
Equity income	36	28
Income before income taxes	370	325
Income tax (benefit) provision	131	106
Net income	239	219
Comprehensive income (loss)	398	(125)
Eliminations [Member]
Condensed Income Statements, Captions [Line Items]
Finance charge income	0	0
Leased vehicle income	0	0
Other income	(146)	(91)
Total revenue	(146)	(91)
Salaries and benefits	0	0
Other operating expenses	(93)	(64)
Total operating expenses	(93)	(64)
Leased vehicle expenses	0	0
Provision for loan losses	0	0
Interest expense	(53)	(27)
Total costs and expenses	(146)	(91)
Equity income	(423)	(367)
Income before income taxes	(423)	(367)
Income tax (benefit) provision	0	0
Net income	(423)	(367)
Comprehensive income (loss)	$ (621)	$ 35