Property and Equipment (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Property and Equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 815	$ 790
Less accumulated depreciation and amortization	(377)	(369)
Property, Plant and Equipment, Total	438	421
Land [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	97	103
Buildings
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	223	213
Non-rental vehicles
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	75	67
Machinery and equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	68	55
Furniture and fixtures [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	152	160
Leasehold improvements [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 200	$ 192