Segment Disclosures - Sales by Product (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Sales And Other Operating Revenues By Product [Abstract]
Consolidated sales and other operating revenues by product		$ 23,693	$ 29,564	$ 52,524
Crude Oil [Member]
Sales And Other Operating Revenues By Product [Abstract]
Consolidated sales and other operating revenues by product		10,801	12,830	23,784
Natural Gas [Member]
Sales And Other Operating Revenues By Product [Abstract]
Consolidated sales and other operating revenues by product		9,401	11,888	20,717
Natural Gas Liquids [Member]
Sales And Other Operating Revenues By Product [Abstract]
Consolidated sales and other operating revenues by product		837	952	2,245
Other Products [Member]
Sales And Other Operating Revenues By Product [Abstract]
Consolidated sales and other operating revenues by product	[1]	$ 2,654	$ 3,894	$ 5,778

[1] *Includes LNG and bitumen.