Properties, Plant and Equipment (Details Textual) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 177,712	$ 182,186	$ 188,396
Dry hole expense related to prior years expenditures, net	42	175	1,573
Accretion expense	668	749	715
Impairment charges	1,021	3,186	4,066
Australia
Property, Plant and Equipment [Line Items]
Property, plant and equipment	55,514	53,962	49,205
Nigeria
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 17,076	$ 17,922	$ 18,773