Segment And Geographic Information (Financial Information Operating Segments) (Details) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Segment Reporting Information [Line Items]
Net financing revenue (loss)	$ 611,000,000	$ 473,000,000	$ 443,000,000	$ 342,000,000	$ 286,000,000	$ 247,000,000	$ 341,000,000	$ 207,000,000	$ 1,869,000,000	$ 1,081,000,000	$ 1,306,000,000
Other revenue	481,000,000	774,000,000	762,000,000	1,012,000,000	812,000,000	385,000,000	873,000,000	827,000,000	3,029,000,000	2,897,000,000	4,416,000,000
Total net revenue (loss)	1,092,000,000	1,247,000,000	1,205,000,000	1,354,000,000	1,098,000,000	632,000,000	1,214,000,000	1,034,000,000	4,898,000,000	3,978,000,000	5,722,000,000
Provision for loan losses	92,000,000	105,000,000	34,000,000	98,000,000	(13,000,000)	57,000,000	59,000,000	85,000,000	329,000,000	188,000,000	357,000,000
Total noninterest expense	1,037,000,000	877,000,000	2,290,000,000	1,120,000,000	1,420,000,000	983,000,000	1,277,000,000	1,061,000,000	5,324,000,000	4,741,000,000	4,973,000,000
Income (loss) from continuing operations before income tax expense	(37,000,000)	265,000,000	(1,119,000,000)	136,000,000	(309,000,000)	(408,000,000)	(122,000,000)	(112,000,000)	(755,000,000)	(951,000,000)	392,000,000
Assets	182,347,000,000				184,059,000,000				182,347,000,000	184,059,000,000	172,008,000,000
Net Interest Income (Loss) after Provision for Loan Losses									1,500,000,000	900,000,000	900,000,000
Automotive finance operations [Member]
Segment Reporting Information [Line Items]
Net financing revenue (loss)									2,827,000,000	2,530,000,000	2,697,000,000
Other revenue									322,000,000	422,000,000	724,000,000
Total net revenue (loss)									3,149,000,000	2,952,000,000	3,421,000,000
Provision for loan losses									253,000,000	89,000,000	260,000,000
Total noninterest expense									1,507,000,000	1,530,000,000	1,404,000,000
Income (loss) from continuing operations before income tax expense									1,389,000,000	1,333,000,000	1,757,000,000
Assets	128,411,000,000				112,591,000,000				128,411,000,000	112,591,000,000	97,961,000,000
Insurance Operations [Member]
Segment Reporting Information [Line Items]
Net financing revenue (loss)									64,000,000	62,000,000	73,000,000
Other revenue									1,150,000,000	1,336,000,000	1,728,000,000
Total net revenue (loss)									1,214,000,000	1,398,000,000	1,801,000,000
Provision for loan losses									0	0	0
Total noninterest expense									1,054,000,000	1,082,000,000	1,244,000,000
Income (loss) from continuing operations before income tax expense									160,000,000	316,000,000	557,000,000
Assets	8,439,000,000				8,036,000,000				8,439,000,000	8,036,000,000	8,789,000,000
Mortgage Operations [Member]
Segment Reporting Information [Line Items]
Net financing revenue (loss)									151,000,000	210,000,000	589,000,000
Other revenue									1,617,000,000	961,000,000	1,998,000,000
Total net revenue (loss)									1,768,000,000	1,171,000,000	2,587,000,000
Provision for loan losses									86,000,000	150,000,000	144,000,000
Total noninterest expense									993,000,000	1,643,000,000	1,671,000,000
Income (loss) from continuing operations before income tax expense									689,000,000	(622,000,000)	772,000,000
Assets	14,744,000,000				33,906,000,000				14,744,000,000	33,906,000,000	36,786,000,000
Corporate And Other [Member]
Segment Reporting Information [Line Items]
Net financing revenue (loss)									(1,173,000,000)	(1,721,000,000)	(2,053,000,000)
Other revenue									(60,000,000)	178,000,000	(34,000,000)
Total net revenue (loss)									(1,233,000,000)	(1,543,000,000)	(2,087,000,000)
Provision for loan losses									(10,000,000)	(51,000,000)	(47,000,000)
Total noninterest expense									1,770,000,000	486,000,000	654,000,000
Income (loss) from continuing operations before income tax expense									(2,993,000,000)	(1,978,000,000)	(2,694,000,000)
Assets	30,753,000,000				29,526,000,000				30,753,000,000	29,526,000,000	28,472,000,000
Commercial Finance Operations [Member]
Segment Reporting Information [Line Items]
Assets	$ 1,500,000,000				$ 1,200,000,000				$ 1,500,000,000	$ 1,200,000,000	$ 1,600,000,000