Property, Plant and Equipment (Details 2) $ in Millions	12 Months Ended
	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Property, Plant and Equipment [Abstract]
Amounts capitalized less than one year after completion of drilling				$ 131	$ 352	$ 484
Amounts capitalized greater than one year after completion of drilling				118	85	126
Total deferred exploratory well costs	$ 437	$ 610	$ 793	$ 249	$ 437	$ 610
Projects that have Exploratory Well Costs that have been Capitalized for Period Greater than One Year, Number of Projects				3	2	3
Increase (Decrease) in Capitalized Exploratory Well Costs that are Pending Determination of Proved Reserves [Roll Forward]
Beginning balance	437	610	793
Additions	299	610	647
Dry well expense	(23)	(148)	(45)
Transfers to development	(388)	(635)	(579)
Dispositions	(76)	0	(206)
Ending balance	$ 249	$ 437	$ 610