Guarantor Condensed Consolidating Financial Statements Guarantor Income Statements (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Condensed Income Statements, Captions [Line Items]
Financial charge income	$ 854	$ 830
Leased vehicle income	431	200
Other income	69	67
Total revenue	1,354	1,097
Salaries and benefits	165	136
Other operating expenses	141	133
Total operating expenses	306	269
Leased vehicle expenses	327	156
Provision for loan losses	155	135
Interest expense	380	315
Total costs and expenses	1,168	875
Equity income	28	0
Income before income taxes	214	222
Income tax (benefit) provision	64	77
Net income	150	145
Comprehensive (loss) income	(196)	150
Parent Company [Member]
Condensed Income Statements, Captions [Line Items]
Financial charge income	0	0
Leased vehicle income	0	0
Other income	7	20
Total revenue	7	20
Salaries and benefits	0	0
Other operating expenses	54	1
Total operating expenses	54	1
Leased vehicle expenses	0	0
Provision for loan losses	0	0
Interest expense	94	55
Total costs and expenses	148	56
Equity income	238	170
Income before income taxes	97	134
Income tax (benefit) provision	(53)	(11)
Net income	150	145
Comprehensive (loss) income	(196)	150
Guarantor [Member]
Condensed Income Statements, Captions [Line Items]
Financial charge income	80	30
Leased vehicle income	0	0
Other income	108	127
Total revenue	188	157
Salaries and benefits	89	53
Other operating expenses	(3)	33
Total operating expenses	86	86
Leased vehicle expenses	0	0
Provision for loan losses	74	60
Interest expense	(2)	11
Total costs and expenses	158	157
Equity income	129	116
Income before income taxes	159	116
Income tax (benefit) provision	11	0
Net income	148	116
Comprehensive (loss) income	90	96
Non-Guarantors [Member]
Condensed Income Statements, Captions [Line Items]
Financial charge income	774	800
Leased vehicle income	431	200
Other income	45	38
Total revenue	1,250	1,038
Salaries and benefits	76	83
Other operating expenses	154	161
Total operating expenses	230	244
Leased vehicle expenses	327	156
Provision for loan losses	81	75
Interest expense	315	305
Total costs and expenses	953	780
Equity income	28	0
Income before income taxes	325	258
Income tax (benefit) provision	106	88
Net income	219	170
Comprehensive (loss) income	(125)	175
Eliminations [Member]
Condensed Income Statements, Captions [Line Items]
Financial charge income	0	0
Leased vehicle income	0	0
Other income	(91)	(118)
Total revenue	(91)	(118)
Salaries and benefits	0	0
Other operating expenses	(64)	(62)
Total operating expenses	(64)	(62)
Leased vehicle expenses	0	0
Provision for loan losses	0	0
Interest expense	(27)	(56)
Total costs and expenses	(91)	(118)
Equity income	(367)	(286)
Income before income taxes	(367)	(286)
Income tax (benefit) provision	0	0
Net income	(367)	(286)
Comprehensive (loss) income	$ 35	$ (271)