Reconciliation of Adjusted EBITDA to Income (Loss) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Segment Reporting [Abstract]
Adjusted EBITDA	$ 903	$ 876	$ 769
Non-vehicle depreciation and amortization	218	180	152
Interest expense related to corporate debt, net	194	209	228
Early extinguishment of debt	23	56	147
Transaction-related costs, net	68	13	51
Restructuring Charges	18	26	61
Impairment	0	0	33
Income before income taxes	$ 382	$ 392	$ 97