Segment Information (Details) $ in Millions	3 Months Ended
	Mar. 31, 2023 USD ($) segment	Mar. 31, 2022 USD ($)	Dec. 31, 2022 USD ($)
Segment Reporting Information [Line Items]
Number of operating segments | segment	4
Net financing revenue and other interest income (loss)	$ 1,602	$ 1,693
Other revenue	498	442
Total net revenue	2,100	2,135
Provision for credit losses	446	167
Total noninterest expense	1,266	1,122
Income from continuing operations before income tax expense	388	846
Total assets	196,165	184,297	$ 191,826
Net financing revenue and other interest income after the provision for credit losses	1,200	1,500
Automotive Finance operations
Segment Reporting Information [Line Items]
Other revenue	77	68
Insurance operations
Segment Reporting Information [Line Items]
Other revenue	381	270
Mortgage Finance operations
Segment Reporting Information [Line Items]
Other revenue	4	14
Corporate Finance operations
Segment Reporting Information [Line Items]
Other revenue	29	24
Operating Segments | Automotive Finance operations
Segment Reporting Information [Line Items]
Net financing revenue and other interest income (loss)	1,322	1,295
Other revenue	77	68
Total net revenue	1,399	1,363
Provision for credit losses	351	104
Total noninterest expense	606	534
Income from continuing operations before income tax expense	442	725
Total assets	111,960	105,754
Operating Segments | Insurance operations
Segment Reporting Information [Line Items]
Net financing revenue and other interest income (loss)	26	17
Other revenue	381	270
Total net revenue	407	287
Provision for credit losses	0	0
Total noninterest expense	315	274
Income from continuing operations before income tax expense	92	13
Total assets	8,867	9,220
Operating Segments | Mortgage Finance operations
Segment Reporting Information [Line Items]
Net financing revenue and other interest income (loss)	54	53
Other revenue	4	14
Total net revenue	58	67
Provision for credit losses	(1)	0
Total noninterest expense	38	56
Income from continuing operations before income tax expense	21	11
Total assets	19,290	18,596
Operating Segments | Corporate Finance operations
Segment Reporting Information [Line Items]
Net financing revenue and other interest income (loss)	103	83
Other revenue	29	24
Total net revenue	132	107
Provision for credit losses	15	6
Total noninterest expense	45	37
Income from continuing operations before income tax expense	72	64
Total assets	10,226	8,086
Corporate and Other
Segment Reporting Information [Line Items]
Net financing revenue and other interest income (loss)	97	245
Other revenue	7	66
Total net revenue	104	311
Provision for credit losses	81	57
Total noninterest expense	262	221
Income from continuing operations before income tax expense	(239)	33
Total assets	$ 45,822	$ 42,641