Property and Equipment, net Property and Equipment, net -Tangible Asset Impairments (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Property, Plant and Equipment [Line Items]
Tangible Asset Impairment Charges	$ 138	$ 2,576	$ 631
Continuing Operations [Member]
Property, Plant and Equipment [Line Items]
Tangible Asset Impairment Charges	60	2,381	181
Discontinued Operations [Member]
Property, Plant and Equipment [Line Items]
Tangible Asset Impairment Charges	$ 78	$ 195	$ 450