Acquisitions and Divestitures - Narrative (Details) $ in Millions					1 Months Ended	3 Months Ended		12 Months Ended
	Apr. 11, 2018 USD ($) MMBoe $ / bbl	Mar. 14, 2018 USD ($) shares	Jan. 31, 2018 USD ($)	Apr. 24, 2017 USD ($) shares	Jan. 31, 2018 USD ($)	Mar. 31, 2018 USD ($) shares	Mar. 31, 2017 USD ($) well	Dec. 31, 2017 USD ($) MMBoe shares	Jan. 29, 2018	Jan. 28, 2018	Jun. 30, 2017 USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Long-Term Debt				$ 595
Gain (loss) on divestiture						$ 588	$ 0
Liabilities Associated with Assets Held for Sale						231		$ 55
Asset Impairments						$ 168	0
Undeveloped Leasehold Costs				1,571
Equity owned (units) | shares						21,692,198		21,692,198
Proceeds from divestiture						$ 70	40
Consideration				2,488
Cash consideration				637
Fair value of common stock issued				1,851
Proceeds from sale						308	$ 0
Intangible assets						334		$ 0
Goodwill				1,291		1,402		$ 1,310
CONE Gathering LLC
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain (loss) on divestiture					$ 196
Ownership			50.00%		50.00%
Proceeds from divestiture					$ 308
Saddle Butte
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Consideration			$ 681
Cash consideration			663
Liabilities assumed			18		18
Property, plant and equipment						206
Intangible assets						340
Goodwill						111
Clayton Williams Energy
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Long-Term Debt											$ 595
Consideration				2,500
Cash consideration				$ 637
Shares exchange in acquisition (shares) | shares				56,000,000
Fair value of common stock issued				$ 1,900
Goodwill				$ 1,300
Bolt-on acquisition in the Delaware Basin
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Productive oil wells | well							7
Payments to acquire oil and gas properties							$ 301
Undeveloped Leasehold Costs							$ 246
Number of productive wells | well							4
Tamar and Dalit Fields
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Ownership interest									25.00%	32.50%
CNX Midstream Partners
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Equity owned (units) | shares								21,700,000
Ownership interest								33.50%
Disposal Group, Disposed of by Sale, Not Discontinued Operations | Tamar and Dalit Fields
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Discount percent		15.00%
Tax effect		$ 90
Gain (loss) on divestiture		386
Proceeds from divestiture		487
Gain attributable to change in fair value		$ 190
Percentage of divestiture farmed out		7.50%
Estimated capacity | MMBoe								84
Shares received in divestiture (in shares) | shares		38,500,000
Value of shares issued		$ 224
Disposal Group, Disposed of by Sale, Not Discontinued Operations | Southwest Royalties
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from sale					$ 60
Disposal Group, Disposed of by Sale, Not Discontinued Operations | Other Divestitures
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total transaction value						10
Gain (loss) on divestiture						6
Disposal Group, Disposed of by Sale, Not Discontinued Operations | Gulf of Mexico Assets
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Assets						480
Liabilities Associated with Assets Held for Sale						92
Asset Impairments						$ 168
Greenfield Midstream | Saddle Butte
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash consideration			$ 343
Subsequent Event | Disposal Group, Disposed of by Sale, Not Discontinued Operations | Gulf of Mexico Assets
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total transaction value	$ 480
Estimated capacity | MMBoe	23
Proceeds from sale of assets	$ 404
Assets	$ 100
Asset basis, price per barrel (in usd per barrel) | $ / bbl	2
Price benchmark (in usd per barrel) | $ / bbl	63