Property and Equipment (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Property and equipment, net
Property, Plant and Equipment [Line Items]
Equipment	$ 1,392	$ 1,312
Less accumulated depreciation and amortization	(788)	(708)
Property and equipment, net	604	604
Land
Property, Plant and Equipment [Line Items]
Equipment	111	101
Buildings
Property, Plant and Equipment [Line Items]
Equipment	215	210
Non-rental vehicles
Property, Plant and Equipment [Line Items]
Equipment	168	168
Machinery and equipment
Property, Plant and Equipment [Line Items]
Equipment	164	157
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Equipment	338	328
Leasehold improvements
Property, Plant and Equipment [Line Items]
Equipment	$ 396	$ 348