Property and Equipment (Details) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 1,896	$ 2,378
Accumulated depreciation	(909)	(918)
Property and equipment, net	987	1,460
Land
Property, Plant and Equipment [Line Items]
Property and equipment, gross	301	457
Buildings and leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross	677	781
Furniture and equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	806	775
Construction in progress
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 112	$ 365