Quarterly Financial Statements (Details) (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
Quarterly Financial Statements [Abstract]
Net financing revenue (loss)	$ 799	$ 889	$ 866	$ 821	$ 774	$ 737	$ 628	$ 640	$ 3,375	$ 2,779	$ 1,891
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
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
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
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
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
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