Impairments Impairments - Fixed Assets and Other Table (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Property, Plant and Equipment [Line Items]
Impairments of fixed assets and other	$ 838	$ 194	$ 88
Other, Barnett Shale Exit Costs [Member]
Property, Plant and Equipment [Line Items]
Impairments of fixed assets and other	645	0	0
Other Devonian Shale Exit Costs [Member]
Property, Plant and Equipment [Line Items]
Impairments of fixed assets and other	142	0	0
Gas Gathering and Processing Equipment [Member]
Property, Plant and Equipment [Line Items]
Impairments of fixed assets and other	3	0	13
Natural Gas Compressor [Member]
Property, Plant and Equipment [Line Items]
Impairments of fixed assets and other	21	21	11
Buildings and land [Member]
Property, Plant and Equipment [Line Items]
Impairments of fixed assets and other	11	0	18
Exploration and Production Equipment [Member]
Property, Plant and Equipment [Line Items]
Impairments of fixed assets and other	0	0	23
Other [Member]
Property, Plant and Equipment [Line Items]
Impairments of fixed assets and other	$ 16	$ 173	$ 23