Acquisitions and Divestitures (Details) - USD ($) $ in Millions	9 Months Ended		12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Discontinued Operations and Disposal Groups [Abstract]
Aggregate purchase price to acquire proved crude oil properties and related assets	$ 368
Proceeds from Sales of Producing Properties, Acreage and Other Assets	$ 144	$ 91
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