Segment Information (Summary Of Segments Information) (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Segment Reporting Information [Line Items]
Assets Under Vehicle Programs	$ 14,388		$ 14,388		$ 12,779
Revenues	2,753	$ 2,778	7,010	$ 7,074
Adjusted EBITDA	471	476	645	639
Non-vehicle related depreciation and amortization	62	62	195	190
Interest expense	49	44	139	139
Early extinguishment of debt	(10)	0	(10)	(5)
Non-operational charges related to shareholder activist activity			0	9
Transaction-related costs, net	0	11	6	18
Gain on sale of equity method investment in Anji			(44)	0
Restructuring and other related charges	22	4	66	14
Income before income taxes	328	355	273	264
Americas [Member]
Segment Reporting Information [Line Items]
Assets Under Vehicle Programs	10,800		10,800		9,700
Revenues	1,868	1,844	4,822	4,782
Adjusted EBITDA	321	313	508	435
International [Member]
Segment Reporting Information [Line Items]
Assets Under Vehicle Programs	3,600		3,600		$ 3,100
Revenues	885	934	2,188	2,292
Adjusted EBITDA	169	178	187	252
Corporate and Other [Member]
Segment Reporting Information [Line Items]
Revenues	0	0	0	0
Adjusted EBITDA	(19)	(15)	(50)	(48)
Americas [Member]
Segment Reporting Information [Line Items]
Revenues	$ 1,868	$ 1,844	$ 4,822	$ 4,782