Acquisitions and Divestitures (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Business Combinations [Abstract]
Aggregated Purchase Price to Acquire Proved Crude Oil Properties and Related Assets	$ 481
Proceeds from Sales of Producing Properties, Acreage and Other Assets	$ 193	$ 569
Cumulative translation adjustments		383
Restricted cash related to future abandonment liabilities		$ 150