Impairments Impairments - Fixed Assets and Other Table (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Property, Plant and Equipment [Line Items]
Impairments of Fixed Assets and Other	$ 9	$ 751	$ 426	$ 795
Other, Barnett Shale Exit Costs [Member]
Property, Plant and Equipment [Line Items]
Impairments of Fixed Assets and Other	0	616	0	616
Exploration and Production Equipment [Member]
Property, Plant and Equipment [Line Items]
Impairments of Fixed Assets and Other	0	96	0	96
Natural Gas Compressor [Member]
Property, Plant and Equipment [Line Items]
Impairments of Fixed Assets and Other	0	32	0	52
Buildings and Land [Member]
Property, Plant and Equipment [Line Items]
Impairments of Fixed Assets and Other	1	7	3	14
Other [Member]
Property, Plant and Equipment [Line Items]
Impairments of Fixed Assets and Other	$ 8	$ 0	$ 423	$ 17