Property and Equipment (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Property and equipment, net
Property, Plant and Equipment [Line Items]
Equipment	$ 1,480	$ 1,392
Less accumulated depreciation and amortization	(868)	(788)
Property and equipment, net	612	604
Land
Property, Plant and Equipment [Line Items]
Equipment	117	111
Buildings
Property, Plant and Equipment [Line Items]
Equipment	222	215
Non-rental vehicles
Property, Plant and Equipment [Line Items]
Equipment	187	168
Machinery and equipment
Property, Plant and Equipment [Line Items]
Equipment	182	164
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Equipment	345	338
Leasehold improvements
Property, Plant and Equipment [Line Items]
Equipment	$ 427	$ 396