Summary of Significant Accounting Policies - Schedule of Account Activity Related to Resale Value Guarantee Program (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating Lease Vehicles
Operating lease vehicles—beginning of period	$ 2,000,000
Net increase in operating lease vehicles	2,465,703	$ 1,573,860	$ 1,050,264
Operating lease vehicles—end of period	3,530,000	2,000,000
Resale Value Guarantee
Increase in resale value guarantee	(326,934)	(442,295)	(249,492)
Resale Value Guarantee [Member]
Operating Lease Vehicles
Operating lease vehicles—beginning of period	1,556,529	684,590
Net increase in operating lease vehicles	1,355,128	1,047,220
Depreciation expense recorded in cost of automotive leasing revenues	(255,167)	(130,355)
Additional depreciation expense recorded in cost of automotive leasing revenues as a result of early cancellation of resale value guarantee	(13,495)	(21,487)
Additional depreciation expense recorded in cost of automotive leasing revenues result of expiration	(114,264)
Increases to inventory from vehicles returned under our trade- in program and exercises of resale value guarantee	(66,670)	(23,439)
Operating lease vehicles—end of period	2,462,061	1,556,529	684,590
Deferred Revenue
Deferred revenue—beginning of period	679,132	381,096
Net increase in deferred revenue from new vehicle deliveries and reclassification of collateralized borrowing from long-term to short-term	715,011	553,765
Amortization of deferred revenue and short-term collateralized borrowing recorded in automotive leasing revenue	(457,113)	(229,624)
Additional revenue recorded in automotive leasing revenue as a result of early cancellation of resale value guarantee	(5,192)	(12,352)
Recognition of deferred revenue resulting from return of vehicle under trade-in program, expiration, and exercises of resale value guarantee	(15,186)	(13,753)
Deferred revenue—end of period	916,652	679,132	381,096
Resale Value Guarantee
Resale value guarantee liability—beginning of period	1,430,573	487,880
Increase in resale value guarantee	1,267,445	1,013,733
Reclassification from long-term to short-term collateralized borrowing	(116,078)	(29,612)
Additional revenue recorded in automotive leasing revenue as a result of early cancellation of resale value guarantee	(16,543)	(11,042)
Resale value guarantee liability—end of period	2,389,927	1,430,573	$ 487,880
Release of resale value guarantee resulting from return of vehicle under trade-in program and exercises	(62,919)	$ (30,386)
Release of resale value guarantee resulting from expiration of resale value guarantee	$ (112,551)