Reconciliation of Adjusted EBITDA to Income (Loss) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Acquired Indefinite-lived Intangible Assets [Line Items]
Adjusted EBITDA	$ 838	$ 903	$ 876
Non-vehicle depreciation and amortization	253	218	180
Interest expense related to corporate debt, net	(203)	(194)	(209)
Early extinguishment of debt	27	23	56
Restructuring Charges	29	18	26
Transaction-related costs, net	21	68	13
Charges for legal matter	26	0	0
Income before income taxes	279	382	392
Acquisition-related Costs [Member]
Acquired Indefinite-lived Intangible Assets [Line Items]
Non-vehicle depreciation and amortization	$ 59	$ 55	$ 33