Summary of Significant Accounting Policies - Schedule of Account Activity Related to Resale Value Guarantee Program (Detail) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2016	Sep. 30, 2015
Operating Lease Vehicles
Net increase in operating lease vehicles		$ 1,798,214	$ 1,091,382
Resale Value Guarantee
Increase in resale value guarantee		(322,244)	$ (249,548)
Resale Value Guarantee [Member]
Operating Lease Vehicles
Operating lease vehicles—beginning of period	$ 2,126,581	1,556,529
Net increase in operating lease vehicles	375,287	1,085,551
Depreciation expense recorded in cost of automotive leasing revenues	(71,454)	(179,087)
Additional depreciation expense recorded in cost of automotive leasing revenues as a result of early cancellation of resale value guarantee	(5,509)	(11,166)
Additional depreciation expense recorded in cost of automotive leasing revenues result of expiration and exercises of resale value guarantee	(55,009)	(55,009)
Increases to inventory from vehicles returned under our trade- in program	(18,718)	(45,640)
Operating lease vehicles—end of period	2,351,178	2,351,178
Deferred Revenue
Deferred revenue—beginning of period	851,684	679,132
Net increase in deferred revenue from new vehicle deliveries and reclassification of collateralized borrowing from long-term to short-term	188,113	574,226
Amortization of deferred revenue and short-term collateralized borrowing recorded in automotive leasing revenue	(125,411)	(330,093)
Additional revenue recorded in automotive leasing revenue as a result of early cancellation of resale value guarantee	(1,521)	(4,333)
Recognition of deferred revenue resulting from return of vehicle under trade-in program	(3,456)	(9,523)
Deferred revenue—end of period	909,409	909,409
Resale Value Guarantee
Resale value guarantee liability—beginning of period	2,007,347	1,430,573
Increase in resale value guarantee	361,434	1,013,369
Reclassification from long-term to short-term collateralized borrowing	(33,129)	(79,171)
Additional revenue recorded in automotive leasing revenue as a result of early cancellation of resale value guarantee	(4,291)	(10,110)
Release of resale value guarantee resulting from return of vehicle under trade- in program	(15,516)	(38,816)
Release of resale value guarantee resulting from expiration and exercises of resale value guarantee	(55,722)	(55,722)
Resale value guarantee liability—end of period	$ 2,260,123	$ 2,260,123