Segment Reporting and Geographic Information - Operations Reporting by Revenue (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Total revenue	$ 13,831	$ 14,554	$ 14,016
Operating expenses	1,490	1,564	1,522
Leased vehicle expenses	5,882	6,685	6,917
Provision for loan losses (Note 3)	881	726	642
Interest expense	3,023	3,641	3,225
Equity income	147	166	183
Income before income taxes	2,702	2,104	1,893
North America [Member]
Segment Reporting Information [Line Items]
Total revenue	12,851	13,318	12,771
Operating expenses	1,184	1,172	1,125
Leased vehicle expenses	5,834	6,634	6,879
Provision for loan losses (Note 3)	653	569	490
Interest expense	2,717	3,171	2,735
Equity income	0	0	0
Income before income taxes	2,463	1,772	1,542
International [Member]
Segment Reporting Information [Line Items]
Total revenue	980	1,236	1,245
Operating expenses	306	392	397
Leased vehicle expenses	48	51	38
Provision for loan losses (Note 3)	228	157	152
Interest expense	306	470	490
Equity income	147	166	183
Income before income taxes	$ 239	$ 332	$ 351