Segment Information (Summary Of Segments Information) (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Segment Reporting Information [Line Items]
Revenues	$ 2,371	$ 760	$ 3,743	$ 2,513
Adjusted EBITDA	624	(382)	671	(469)
Less:
Non-vehicle related depreciation and amortization	67	71	135	140
Interest expense	59	51	120	99
Early extinguishment of debt	0	3	129	7
Restructuring and other related charges	22	28	42	72
Transaction-related costs, net	1	1	2	3
Non-operational charges related to shareholder activist activity			0	4
COVID-19 charges	0	73	18	80
Unprecedented personal-injury and other legal matters, net	(11)	0	(11)
Income (loss) before income taxes	486	(609)	236	(874)
COVID-19 charges	0	73	18	80
Minimum annual guaranteed rent in excess of concession fees, net	(3)	30	16	30
Vehicles damaged in overflow parking lots, net of insurance proceeds	2	28	(4)	33
Incremental cleaning supplies to sanitize vehicles and facilities, and over flow parking for idle vehicles	0	15	0	17
Other charges	1	0	6	0
Operating expense
Less:
Non-vehicle related depreciation and amortization	3		3
COVID-19 charges	0	72	17	79
COVID-19 charges	0	72	17	79
Selling, General and Administrative Expenses
Less:
Non-vehicle related depreciation and amortization	2		2
COVID-19 charges	0	1	1	1
COVID-19 charges	0	1	1	1
Corporate and Other
Segment Reporting Information [Line Items]
Revenues	0	0	0	0
Adjusted EBITDA	(18)	(9)	(29)	(26)
Americas | Geographical
Segment Reporting Information [Line Items]
Revenues	1,974	565	3,054	1,822
Adjusted EBITDA	634	(233)	742	(263)
International | Geographical
Segment Reporting Information [Line Items]
Revenues	397	195	689	691
Adjusted EBITDA	$ 8	$ (140)	$ (42)	$ (180)