Components of Company's Vehicles (Detail) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Disclosure Components Of Companys Vehicles [Abstract]
Rental vehicles	$ 12,548	$ 11,652
Less: Accumulated depreciation	(1,670)	(1,652)
Rental Vehicles Net, Total	10,878	10,000
Vehicles held for sale	596	626
Vehicles, net	$ 11,474	$ 10,626