Segment Information (Summary Of Segments Information) (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Segment Reporting Information [Line Items]
Segment Reporting, Change in Measurement Method		$ 15		$ 49
Revenues	$ 2,577	2,542	$ 6,600	6,598
Adjusted EBITDA	431	417	775	747
Non-vehicle related depreciation and amortization	56	46	161	132
Interest expense	49	50	146	161
Interest expense related to corporate debt, net:			146	161
Early Debt Extinguishment			23	56
Transaction-related costs	8	7	57	23
Restructuring expense	6	8	10	16
Income before income taxes	312	306	378	359
Americas
Segment Reporting Information [Line Items]
Revenues	1,776	1,742	4,707	4,614
Adjusted EBITDA	279	275	572	562
International
Segment Reporting Information [Line Items]
Segment Reporting, Change in Measurement Method		2		7
Revenues	801	800	1,893	1,984
Adjusted EBITDA	168	158	245	227
Corporate and Other [Member]
Segment Reporting Information [Line Items]
Revenues	0	0	0	0
Adjusted EBITDA	$ (16)	$ (16)	$ (42)	$ (42)