Segment Reporting - Operations Reporting by Revenue (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Segment Reporting Information [Line Items]
Total revenue	$ 3,620	$ 3,411
Operating expenses	370	365
Leased vehicle expenses	1,814	1,787
Provision for loan losses	175	136
Interest expense	947	732
Equity income	45	52
Income before income taxes	359	443
Operating Segments [Member] | North America Segment [Member]
Segment Reporting Information [Line Items]
Total revenue	3,306	3,085
Operating expenses	276	271
Leased vehicle expenses	1,803	1,778
Provision for loan losses	139	97
Interest expense	823	597
Equity income	0	0
Income before income taxes	265	342
Operating Segments [Member] | International Segment [Member]
Segment Reporting Information [Line Items]
Total revenue	314	326
Operating expenses	94	94
Leased vehicle expenses	11	9
Provision for loan losses	36	39
Interest expense	124	135
Equity income	45	52
Income before income taxes	$ 94	$ 101