Impairments - Narrative (Details) $ in Millions	12 Months Ended
	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($) Compressor	Dec. 31, 2015 USD ($)
Property, Plant and Equipment [Line Items]
Impairment of Oil and Natural Gas Properties	$ 0	$ 2,564	$ 18,238
Impairments of Fixed Assets and Other	421	838	194
Loss on Transportation Agreement	4,598	4,778	7,130
Provision for legal contingencies, net	(42)	87	340
Gain (Loss) on Contract Termination			18
Contractual Dispute [Member]
Property, Plant and Equipment [Line Items]
Impairments of Fixed Assets and Other			47
Note Receivable [Member]
Property, Plant and Equipment [Line Items]
Impairments of Fixed Assets and Other			22
Net Acreage Shortfall [Member] | Total [Member]
Property, Plant and Equipment [Line Items]
Provision for legal contingencies, net			$ 70
Other, Barnett Shale Exit Costs,Termination of Gathering Agreement [Member]
Property, Plant and Equipment [Line Items]
Impairments of Fixed Assets and Other		361
Loss on Contract Termination		361
Other, Barnett Shale Exit Costs, Other Property and Equipment [Member]
Property, Plant and Equipment [Line Items]
Impairments of Fixed Assets and Other		284
Exploration and Production Equipment, Buildings and Land, Devonian Shale [Member]
Property, Plant and Equipment [Line Items]
Impairments of Fixed Assets and Other		142
Transportation Equipment [Member] | Natural Gas [Member]
Property, Plant and Equipment [Line Items]
Loss on Contract Termination	126
Transportation Equipment [Member] | Oil [Member]
Property, Plant and Equipment [Line Items]
Loss on Transportation Agreement	$ 290
Natural Gas Compressors, Obsolete [Member]
Property, Plant and Equipment [Line Items]
Impairments of Fixed Assets and Other		$ 13
Equipment, Number of Units | Compressor		205
Natural Gas Compressors, Difference Between Sales Price and Carrying Value [Member]
Property, Plant and Equipment [Line Items]
Impairments of Fixed Assets and Other		$ 8
Equipment, Number of Units | Compressor		155