Guarantor Consolidating Financial Statements - Guarantor Income Statements (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Condensed Income Statements, Captions [Line Items]
Finance charge income									$ 3,256	$ 2,846	$ 2,848
Leased vehicle income									8,606	5,896	2,795
Other income									289	241	224
Total revenue	$ 3,252	$ 3,161	$ 2,990	$ 2,748	$ 2,554	$ 2,360	$ 2,138	$ 1,931	12,151	8,983	5,867
Salaries and benefits									845	735	609
Other operating expenses									545	515	442
Total operating expenses									1,390	1,250	1,051
Leased vehicle expenses									6,415	4,506	2,190
Provision for loan losses (Note 4)									757	644	603
Interest expense									2,566	1,972	1,460
Total costs and expenses									11,128	8,372	5,304
Equity income									173	151	116
Income from continuing operations before income taxes	450	186	270	179	242	134	143	138	1,196	762	679
Income tax (benefit) provision	(240)								111	105	194
Income from continuing operations									1,085	657	485
Loss from discontinued operations, net of tax									(424)	97	161
Net income	$ 195	$ 202	$ 62	$ 202	$ 254	$ 147	$ 189	$ 164	661	754	646
Net income attributable to common shareholder									645	754	646
Comprehensive income									1,131	620	(25)
General Motors Financial Company, Inc. [Member]
Condensed Income Statements, Captions [Line Items]
Finance charge income									0	0	0
Leased vehicle income									0	0	0
Other income									1	(1)	13
Total revenue									1	(1)	13
Salaries and benefits									0	0	0
Other operating expenses									258	2	64
Total operating expenses									258	2	64
Leased vehicle expenses									0	0	0
Provision for loan losses (Note 4)									0	0	0
Interest expense									1,102	557	488
Total costs and expenses									1,360	559	552
Equity income									2,050	994	941
Income from continuing operations before income taxes									691	434	402
Income tax (benefit) provision									(238)	(341)	(224)
Income from continuing operations									929	775	626
Loss from discontinued operations, net of tax									(268)	(21)	20
Net income									661	754	646
Net income attributable to common shareholder									645
Comprehensive income									1,131	620	(25)
Guarantor [Member]
Condensed Income Statements, Captions [Line Items]
Finance charge income									513	432	403
Leased vehicle income									0	0	0
Other income									1,169	883	505
Total revenue									1,682	1,315	908
Salaries and benefits									688	597	332
Other operating expenses									(43)	200	105
Total operating expenses									645	797	437
Leased vehicle expenses									0	0	0
Provision for loan losses (Note 4)									430	378	398
Interest expense									72	296	18
Total costs and expenses									1,147	1,471	853
Equity income									1,615	771	579
Income from continuing operations before income taxes									2,150	615	634
Income tax (benefit) provision									158	(89)	25
Income from continuing operations									1,992	704	609
Loss from discontinued operations, net of tax									(13)	0	0
Net income									1,979	704	609
Net income attributable to common shareholder									1,979
Comprehensive income									2,031	718	498
Non-Guarantors [Member]
Condensed Income Statements, Captions [Line Items]
Finance charge income									2,743	2,414	2,445
Leased vehicle income									8,606	5,896	2,795
Other income									(7)	34	97
Total revenue									11,342	8,344	5,337
Salaries and benefits									157	138	277
Other operating expenses									831	715	524
Total operating expenses									988	853	801
Leased vehicle expenses									6,415	4,506	2,190
Provision for loan losses (Note 4)									327	266	205
Interest expense									1,765	1,392	1,094
Total costs and expenses									9,495	7,017	4,290
Equity income									173	151	116
Income from continuing operations before income taxes									2,020	1,478	1,163
Income tax (benefit) provision									191	535	393
Income from continuing operations									1,829	943	770
Loss from discontinued operations, net of tax									(143)	118	141
Net income									1,686	1,061	911
Net income attributable to common shareholder									1,686
Comprehensive income									2,195	933	225
Eliminations [Member]
Condensed Income Statements, Captions [Line Items]
Finance charge income									0	0	0
Leased vehicle income									0	0	0
Other income									(874)	(675)	(391)
Total revenue									(874)	(675)	(391)
Salaries and benefits									0	0	0
Other operating expenses									(501)	(402)	(251)
Total operating expenses									(501)	(402)	(251)
Leased vehicle expenses									0	0	0
Provision for loan losses (Note 4)									0	0	0
Interest expense									(373)	(273)	(140)
Total costs and expenses									(874)	(675)	(391)
Equity income									(3,665)	(1,765)	(1,520)
Income from continuing operations before income taxes									(3,665)	(1,765)	(1,520)
Income tax (benefit) provision									0	0	0
Income from continuing operations									(3,665)	(1,765)	(1,520)
Loss from discontinued operations, net of tax									0	0	0
Net income									(3,665)	(1,765)	(1,520)
Net income attributable to common shareholder									(3,665)
Comprehensive income									$ (4,226)	$ (1,651)	$ (723)