Segment Information (Narrative) (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Segment Reporting Information [Line Items]
Assets Under Vehicle Programs	$ 10,043		$ 10,043		$ 13,815
Operating Leases, Rent Expense, Minimum Rentals	11		41
Vehicle depreciation and lease charges, net	256	$ 551	1,089	$ 1,579
Vehicles deprecation and lease charges, net [Member]
Segment Reporting Information [Line Items]
Vehicle depreciation and lease charges, net	1		1
Americas [Member]
Segment Reporting Information [Line Items]
Assets Under Vehicle Programs	7,800		7,800		10,500
International [Member]
Segment Reporting Information [Line Items]
Assets Under Vehicle Programs	$ 2,200		$ 2,200		$ 3,300