Segment Information (Summary Of Segments Information) (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Segment Reporting Information [Line Items]
Assets Under Vehicle Programs	$ 15,437		$ 15,437		$ 12,779
Revenues	2,337	$ 2,328	4,257	$ 4,296
Adjusted EBITDA	175	161	174	163
Non-vehicle related depreciation and amortization	66	67	133	128
Interest expense	48	49	90	95
Early extinguishment of debt	0	0	0	(5)
Non-operational charges related to shareholder activist activity			0	9
Transaction-related costs, net	1	3	6	7
Gain on sale of equity method investment in Anji	(44)	0	(44)	0
Restructuring and other related charges	23	4	44	10
Income before income taxes	81	38	(55)	(91)
Americas [Member]
Segment Reporting Information [Line Items]
Assets Under Vehicle Programs	11,800		11,800		9,700
Revenues	1,627	1,590	2,954	2,938
Adjusted EBITDA	152	107	187	122
International [Member]
Segment Reporting Information [Line Items]
Assets Under Vehicle Programs	3,600		3,600		$ 3,100
Revenues	710	738	1,303	1,358
Adjusted EBITDA	39	71	18	74
Corporate and Other [Member]
Segment Reporting Information [Line Items]
Revenues	0	0	0	0
Adjusted EBITDA	(16)	(17)	(31)	(33)
Americas [Member]
Segment Reporting Information [Line Items]
Revenues	$ 1,627	$ 1,590	$ 2,954	$ 2,938