Segment Information (Narrative) (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Segment Reporting Information [Line Items]
Document Period End Date	Mar. 31, 2018
Revenues	$ 1,968	$ 1,839
Adjusted EBITDA	2	(27)
Non Vehicle Related Depreciation And Amortization	61	63
Restructuring and other related charges	6	7
Loss before income taxes	(129)	(165)
Assets Under Vehicle Programs	13,256		$ 11,879
Total assets exclusive of assets under vehicle programs	5,966		5,820
Americas
Segment Reporting Information [Line Items]
Adjusted EBITDA	15	(20)
Assets Under Vehicle Programs	10,200		9,000
International [Member]
Segment Reporting Information [Line Items]
Revenues	620	525
Adjusted EBITDA	3	7
Assets Under Vehicle Programs	3,100		$ 2,900
Corporate and Other [Member]
Segment Reporting Information [Line Items]
Revenues	0	0
Adjusted EBITDA	$ (16)	$ (14)