Segment Reporting - Schedule of Operations Reporting by Revenue (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Segment Reporting Information [Line Items]
Revenues	$ 4,164	$ 3,811
Costs and expenses
(Gain) loss on termination of leased vehicles	156	202
Provision for loan losses	328	204
Interest expense	1,597	1,396
Equity income	12	32
Income before income taxes	685	737
Reportable Segments
Segment Reporting Information [Line Items]
Revenues	4,155	3,809
Costs and expenses
Income before income taxes	700	749
North America
Segment Reporting Information [Line Items]
Revenues	3,778	3,415
Costs and expenses
Salaries and benefits	272	255
Leased vehicle depreciation	1,185	1,224
(Gain) loss on termination of leased vehicles	156	(202)
Provision for loan losses	292	171
Interest expense	1,424	1,230
GM Protection claim losses	10	5
Other segment items	126	97
Equity income	0	0
Income before income taxes	625	635
International
Segment Reporting Information [Line Items]
Revenues	377	394
Costs and expenses
Salaries and benefits	38	37
Leased vehicle depreciation	18	19
(Gain) loss on termination of leased vehicles	0	1
Provision for loan losses	36	33
Interest expense	173	167
GM Protection claim losses	0	0
Other segment items	49	56
Equity income	12	32
Income before income taxes	75	114
Other Operating Segment
Segment Reporting Information [Line Items]
Revenues	9	2
Costs and expenses
Income before income taxes	$ (15)	$ (12)