Property and Equipment (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Property and Equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 897	$ 871
Less accumulated depreciation and amortization	(467)	(426)
Property, Plant and Equipment, Total	430	445
Land
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	96	98
Buildings
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	212	226
Non-rental vehicles
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	93	86
Machinery and equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	87	78
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	188	171
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 221	$ 212