Segment Information (Summary Of Segments Information) (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Segment Reporting Information [Line Items]
Revenues	$ 1,372	$ 1,753
Adjusted EBITDA	47	(87)
Less:
Non-vehicle related depreciation and amortization	68	69
Interest expense	61	48
Early extinguishment of debt	129	4
Restructuring and other related charges	20	44
COVID-19 charges	18	7
Transaction-related costs, net	1	2
Non-operational charges related to shareholder activist activity	0	4
Loss before income taxes	(250)	(265)
Minimum annual guaranteed rent in excess of concession fees	19
Other charges	5
Vehicles damaged in overflow parking lots, net of insurance proceeds	(6)
Assets under vehicle programs	10,135		$ 9,173
Selling, General and Administrative Expenses
Less:
COVID-19 charges	1
Operating Expense
Less:
COVID-19 charges	17	7
Vehicles damaged in overflow parking lots, net of insurance proceeds		5
Incremental cleaning supplies		2
Corporate and Other
Segment Reporting Information [Line Items]
Revenues	0	0
Adjusted EBITDA	(11)	(17)
Americas
Less:
Assets under vehicle programs	8,200		7,200
Americas | Geographical
Segment Reporting Information [Line Items]
Revenues	1,080	1,257
Adjusted EBITDA	108	(30)
International
Less:
Assets under vehicle programs	1,900		$ 2,000
International | Geographical
Segment Reporting Information [Line Items]
Revenues	292	496
Adjusted EBITDA	$ (50)	$ (40)