Segment Reporting - Revenue (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Segment Reporting Information [Line Items]
Total revenue	$ 3,659	$ 3,518	$ 10,918	$ 10,417
Operating expenses	384	369	1,131	1,116
Leased vehicle expenses	1,574	1,677	5,025	5,148
Provision for loan losses	150	180	504	444
Interest expense	879	838	2,778	2,373
Equity income	39	44	126	141
Income before income taxes	711	498	1,606	1,477
North America Segment [Member]
Segment Reporting Information [Line Items]
Total revenue	3,355	3,217	9,993	9,482
Operating expenses	291	273	848	820
Leased vehicle expenses	1,557	1,668	4,987	5,121
Provision for loan losses	113	146	394	333
Interest expense	759	715	2,413	1,997
Equity income	0	0	0	0
Income before income taxes	635	415	1,351	1,211
International Segment [Member]
Segment Reporting Information [Line Items]
Total revenue	304	301	925	935
Operating expenses	93	96	283	296
Leased vehicle expenses	17	9	38	27
Provision for loan losses	37	34	110	111
Interest expense	120	123	365	376
Equity income	39	44	126	141
Income before income taxes	$ 76	$ 83	$ 255	$ 266