Selected Quarterly Financial Data (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Quarterly Financial Information Disclosure [Abstract]
Total revenue	$ 3,182	$ 3,081	$ 3,099	$ 3,020	$ 2,981	$ 2,863	$ 2,802	$ 2,731	$ 12,382	$ 11,377	$ 10,909
Depreciation on vehicles subject to operating leases	(969)	(907)	(963)	(1,028)	(1,045)	(989)	(1,037)	(1,064)	(3,867)	(4,135)	(4,329)
Interest expense	(1,032)	(989)	(997)	(912)	(867)	(810)	(769)	(729)	(3,930)	(3,175)	(2,755)
Total financing margin and other revenue	1,181	1,185	1,139	1,080	1,069	1,064	996	938	4,585	4,067	3,495
Provision for credit losses	165	156	92	119	168	169	99	152	532	588	547
Net income	$ 526	$ 518	$ 479	$ 701	$ 1,814	$ 414	$ 446	$ 333	$ 2,224	3,007	$ 1,373
Net Deferred Federal Tax Expense/(Benefit) Related to Tax Cuts and Jobs Act										$ (1,400)