Property and Equipment Property and Equipment - Tangible Impairment Assets (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Property, Plant and Equipment [Line Items]
Tangible asset impairment charges	$ 0	$ 53	$ 0	$ 129
Continuing Operations [Member]
Property, Plant and Equipment [Line Items]
Tangible asset impairment charges	0	53	0	61
Discontinued Operations [Member]
Property, Plant and Equipment [Line Items]
Tangible asset impairment charges	$ 0	$ 0	$ 0	$ 68