Segment Reporting - Revenue (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Segment Reporting Information [Line Items]
Total revenue	$ 3,421	$ 3,659	$ 10,405	$ 10,918
Operating expenses	394	384	1,097	1,131
Leased vehicle expenses	1,126	1,574	4,602	5,025
Provision for loan losses	31	150	824	504
Interest expense	709	879	2,332	2,778
Equity income	46	39	113	126
Income before income taxes	1,207	711	1,663	1,606
North America Segment [Member]
Segment Reporting Information [Line Items]
Total revenue	3,196	3,355	9,670	9,993
Operating expenses	312	291	879	848
Leased vehicle expenses	1,114	1,557	4,566	4,987
Provision for loan losses	(26)	113	609	394
Interest expense	643	759	2,091	2,413
Equity income	0	0	0	0
Income before income taxes	1,153	635	1,525	1,351
International Segment [Member]
Segment Reporting Information [Line Items]
Total revenue	225	304	735	925
Operating expenses	82	93	218	283
Leased vehicle expenses	12	17	36	38
Provision for loan losses	57	37	215	110
Interest expense	66	120	241	365
Equity income	46	39	113	126
Income before income taxes	$ 54	$ 76	$ 138	$ 255