Divestitures (Details) - USD ($) $ in Millions	6 Months Ended		12 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Discontinued Operations and Disposal Groups [Abstract]
Proceeds from Sales of Producing Properties, Acreage and Other Assets	$ 116	$ 75
Proceeds from Sales of Canadian Operations			$ 400
Cumulative Translation Adjustments Reclassified to Income in Connection With Sales of Canadian Operations			383
Restricted Cash Released in Connection With Sales of Canadian Operations			$ 150