Consolidated Statement of Income (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Financing Revenue and Other Interest Income [Abstract]
Interest and fees on finance receivables and loans									$ 4,457	$ 4,529	$ 4,539
Interest on loans held-for-sale									1	20	98
Interest on trading assets									0	0	10
Interest and dividends on available-for-sale investment securities									367	325	292
Interest-bearing cash									8	10	24
Operating leases									3,558	3,209	2,379
Total financing revenue and other interest income									8,391	8,093	7,342
Interest Expense [Abstract]
Interest on deposits									664	654	645
Interest on short-term borrowings									52	63	71
Interest on long-term debt									2,067	2,602	3,336
Total interest expense									2,783	3,319	4,052
Depreciation expense on operating lease assets									2,233	1,995	1,399
Net financing revenue (loss)	799	889	866	821	774	737	628	640	3,375	2,779	1,891
Other revenue [Abstract]
Servicing fees									31	126	409
Servicing asset valuation and hedge activities, net									0	(213)	(4)
Total servicing income, net									31	(87)	405
Insurance premiums and service revenue earned									979	1,012	1,055
Gain (loss) on mortgage and automotive loans, net									7	55	379
Gain (loss) on extinguishment of debt									(202)	(59)	(148)
Other gain (loss) on investments, net									181	180	146
Other income, net of losses									280	383	737
Total other revenue	215	375	365	321	325	371	402	386	1,276	1,484	2,574
Total net revenue (loss)	1,014	1,264	1,231	1,142	1,099	1,108	1,030	1,026	4,651	4,263	4,465
Provision for loan losses	155	102	63	137	140	141	89	131	457	501	329
Noninterest Expense [Abstract]
Compensation and benefits expense									947	1,019	1,106
Insurance losses and loss adjustment expenses									410	405	454
Other operating expenses									1,591	1,981	2,062
Total noninterest expense	672	742	821	713	884	762	801	958	2,948	3,405	3,622
Income (loss) from continuing operations before income tax expense	187	420	347	292	75	205	140	(63)	1,246	357	514
Income tax expense (benefit) from continuing operations	36	127	64	94	(4)	28	40	(123)	321	(59)	(856)
Net income (loss) from continuing operations	151	293	283	198	79	177	100	60	925	416	1,370
Income (loss) from discontinued operations, net of tax	26	130	40	29	25	(86)	(1,027)	1,033	225	(55)	(174)
Net income (loss)	$ 177	$ 423	$ 323	$ 227	$ 104	$ 91	$ (927)	$ 1,093	$ 1,150	$ 361	$ 1,196
Earnings Per Share, Basic [Abstract]
Net income (loss) from continuing operations, Per Basic Share	$ 0.17	$ 0.47	$ 0.45	$ 0.27	$ (0.83)	$ (0.06)	$ (0.24)	$ (0.34)	$ 1.36	$ (1.51)	$ 1.38
Income (Loss) from Discontinued Operations, Net of Tax, Per Basic Share									$ 0.47	$ (0.13)	$ (0.42)
Net (loss) income, Basic	$ 0.23	$ 0.74	$ 0.54	$ 0.33	$ (0.78)	$ (0.27)	$ (2.73)	$ 2.16	$ 1.83	$ (1.64)	$ 0.96
Earnings Per Share, Diluted [Abstract]
Net income (loss) from continuing operations, Per Diluted Share	$ 0.17	$ 0.47	$ 0.45	$ 0.27	$ (0.83)	$ (0.06)	$ (0.24)	$ (0.34)	$ 1.36	$ (1.51)	$ 1.38
Income (loss) from discontinued operations, net of tax									$ 0.47	$ (0.13)	$ (0.42)
Net (loss) income, Diluted	$ 0.23	$ 0.74	$ 0.54	$ 0.33	$ (0.78)	$ (0.27)	$ (2.73)	$ 2.16	$ 1.83	$ (1.64)	$ 0.96