Acquisitions and Divestitures - Narrative (Details)								1 Months Ended				3 Months Ended				8 Months Ended	12 Months Ended
	Mar. 14, 2018 USD ($) shares	Feb. 15, 2018 USD ($) $ / bbl	Jan. 31, 2018 USD ($)	Jun. 28, 2017 USD ($) payment $ / MMBTU	Jun. 26, 2017 USD ($) a shares	Apr. 24, 2017 USD ($) a $ / shares shares	Apr. 03, 2017 USD ($) bbl / d mi bbl	Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Jan. 31, 2018 USD ($)	Jan. 31, 2017 USD ($)	Dec. 31, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2017 USD ($) well	Dec. 31, 2018 USD ($) a MMcf / d	Dec. 31, 2017 USD ($) well	Dec. 31, 2016 USD ($) a	Mar. 31, 2019	Jan. 31, 2019 USD ($) a	Feb. 01, 2018 shares	Jan. 29, 2018	Jan. 28, 2018
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Impairment charge																	$ 206,000,000
Proceeds from Divestitures																	1,999,000,000	$ 2,073,000,000	$ 1,241,000,000
Gain (loss) on sale																	843,000,000	326,000,000	$ 238,000,000
Ownership interest sold															35.00%				35.00%
Payments for (proceeds from) businesses and interest in affiliates																	(484,000,000)
Gain (loss) on divestiture																	0	(2,379,000,000)	$ 0
Goodwill								$ 110,000,000	$ 1,400,000,000			$ 110,000,000				$ 1,310,000,000	110,000,000	1,310,000,000
Severance, consulting, investment, advisory, legal and other related merger-related fees																	0	100,000,000	0
Sales Proceeds																			83,000,000
Proceeds from issuance of common limited partners units																	0	312,000,000	299,000,000
Gain (loss) on divestitures																	843,000,000	$ 326,000,000	$ 238,000,000
Saddle Butte
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Consideration transferred			$ 681,000,000
Cash paid			663,000,000
Total Purchase Price Plus Liabilities Assumed			$ 18,000,000							$ 18,000,000
Property, plant and equipment assumed								206,000,000				206,000,000					206,000,000
Finite-lived intangible assets assumed								340,000,000				340,000,000					340,000,000
Immaterial acquisitions
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of productive wells | well																7		7
Payments to acquire oil and gas properties																	$ 3,000,000	$ 26,000,000
Clayton Williams Energy
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Consideration transferred						$ 2,488,000,000
Cash paid						637,000,000
Total Purchase Price Plus Liabilities Assumed						3,798,000,000
Goodwill						$ 1,291,000,000
Stock issued (shares) | shares						56,000,000
Fair Value of Common Stock Issued						$ 1,851,000,000
Share price ($ per share) | $ / shares						$ 34.17
Long-term line of credit						$ 1,300,000,000
Severance, consulting, investment, advisory, legal and other related merger-related fees						100,000,000												23,000,000
Severance, consulting, investment, advisory, legal, and other merger related fees						64,000,000												100,000,000
Noncash share-based compensation expense						$ 36,000,000
Treasury stock redeemed (in shares) | shares						720,000
Consideration transferred, treasury stock						$ 25,000,000
Long-Term Debt						$ 595,000,000
Revenue since acquisition																$ 99,000,000
Pre-tax loss since acquisition																19,000,000
Delaware Basin
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Consideration transferred											$ 301,000,000
Proceeds allocated to undeveloped leasehold cost											246,000,000
Blanco River DevCo | Noble Midstream Partners LP
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Ownership interest acquired					15.00%
Ownership interest acquired, step acquisition					40.00%
Colorado River DevCo | Noble Midstream Partners LP
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Ownership interest acquired					20.00%
Blanco River and Colorado River DevCos | Subsidiaries
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Consideration transferred					$ 270,000,000
Cash paid					$ 245,000,000
Stock issued (shares) | shares					562,430
Developed gas and oil area | a					111,000
Proceeds from issuance of common limited partners units					$ 138,000,000
Proceeds from debt					90,000,000
Blanco River and Colorado River DevCos | Noble Midstream Partners LP
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Consideration transferred					$ 270,000,000
Advantage Pipeline | Noble Midstream Partners LP
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Consideration transferred							$ 133,000,000
Length of pipeline | mi							70
Shipping capacity per day (bbls/day) | bbl / d							150
Storage capacity (bbls) | bbl							490
DJ Basin
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Acreage exchange | a																	12,900
Mustang and Wells Ranch
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Acreage exchange | a																	12,300
Delaware Basin | Clayton Williams Energy
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gas and oil area acquired | a						71,000
Additional gas and oil area acquired | a						64,000
Long-Term Debt						$ 595,000,000
Permian | Clayton Williams Energy
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gas and oil area acquired | a						100,000
CONE Gathering LLC
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Ownership percentage			50.00%							50.00%												34.10%
Greendfield Midstream | Saddle Butte
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash paid			$ 343,000,000
Noble Midstream Partners LP | Advantage Pipeline
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Ownership percentage							50.00%
EPIC NGL Pipeline | Subsequent Event
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Ownership interest in equity method investments																				15.00%
EPIC Crude Oil Pipeline | Subsequent Event
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Ownership interest in equity method investments																				30.00%
Tamar and Dalit Fields
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Ownership interest in equity method investments																							25.00%	32.50%
CNX Midstream Partners
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from Sale of CONE Gathering LLC and CNX Midstream Partners Common Units																	$ 387,000,000
Owned (shares) | shares																						21,700,000
Realized gain (loss) on sale																	307,000,000
Saddle Butte
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Ownership interest in equity method investments			54.40%							54.40%
Advantage Joint Venture
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Payments to acquire interest in joint venture							$ 67,000,000
CONE Gathering LLC
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from Divestitures										$ 309,000,000
Gain (loss) on sale										196,000,000
Greeley Crescent Assets
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from Divestitures									$ 68,000,000
Ward County
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from Divestitures								63,000,000
Gain (loss) on divestiture								16,000,000
Marcellus Shale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total consideration value				$ 1,200,000,000
Sales Proceeds				1,000,000,000.0
Consideration adjustment				$ 100,000,000
Additional consideration, number of payments, divestiture | payment				3
Additional consideration, Individual payment amounts				$ 33,300,000
Minimum Appalachia Dominion, South Point index price for contingent consideration to be required ($ per MMBtu) | $ / MMBTU				3.30
Loss on sale, before tax																	2,300,000,000
Loss on sale of property, after tax																	$ 1,500,000,000
Asset consideration				$ 3,400,000,000
Natural gas production per day | MMcf / d																	204
Marcellus Shale | Leaseholds and Leasehold Improvements
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Asset consideration				$ 883,000,000
Onshore US
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from Divestitures																	$ 671,000,000
DJ Basin
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from Divestitures																	568,000,000
Mineral and Royalty Assets
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sales Proceeds																	335,000,000
Gain (loss) on disposition of assets																	$ 334,000,000
Mineral and royalty assets, area | a																	140,000
CONSOL Carried Cost Obligation
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash remitted															$ 213,000,000
Mustang and Wells Ranch
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Land exchanged (acres) | a																			11,700
Bronco Development Area
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Land sold (acres) | a																			13,500
Tamar Field, Offshore Israel
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total consideration value															$ 431,000,000				$ 431,000,000
Ownership interest sold															3.50%				3.50%
Sales Proceeds																			$ 316,000,000
Gain (loss) on divestitures																			$ 261,000,000
Ownership percentage required per agreement															25.00%				25.00%
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 consideration value		$ 480,000,000
Impairment charge														$ 168,000,000
Proceeds from Divestitures													$ 384,000,000
Gain (loss) on sale													$ (24,000,000)
Contingent consideration, asset		$ 100,000,000
Asset basis, price per barrel (in usd per bbl) | $ / bbl		2
Asset basis, price per barrel benchmark (in usd per bbl) | $ / bbl		63
Contingent consideration, liability								3,000,000				3,000,000					$ 3,000,000
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]
Gain (loss) on sale																	376,000,000
Ownership interest sold	7.50%
Shares received in divestiture of interest in equity method investment (in shares) | shares	38,500,000
Consideration, shares issued, value	$ 224,000,000
Tax effect of gain (loss)																	86,000,000
Gain (loss) on divestiture of equity method investments, change in fair value	$ 190,000,000
Discount rate for impairment model	15.00%
Gross unrealized loss																	27,000,000
Dividend income																	31,000,000
Payments for (proceeds from) investments												(163,000,000)
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 of CONE Gathering LLC and CNX Midstream Partners Common Units										$ 60,000,000
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 consideration value								81,000,000				81,000,000				$ 39,000,000	81,000,000	39,000,000
Gain (loss) on sale																	4,000,000	$ (6,000,000)
Disposal Group, Disposed of by Sale, Not Discontinued Operations | Reeves County Assets | Subsequent Event
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total consideration value																					$ 132,000,000
Proved and unproved non-core acreage | a																					13,000
Disposal Group, Disposed of by Sale, Not Discontinued Operations | Producing and Undeveloped Net Acres in the DJ Basin
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sales Proceeds																			$ 486,000,000
Land sold (acres) | a																			33,100
Consideration expected															$ 505,000,000				$ 505,000,000
Disposal Group, Disposed of by Sale, Not Discontinued Operations | Bowdoin Property
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sales Proceeds																			152,000,000
Gain (loss) on divestitures																			(23,000,000)
Disposal Group, Disposed of by Sale, Not Discontinued Operations | Alon A And Alon C
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total consideration value															$ 73,000,000				$ 73,000,000
Ownership interest sold															47.00%				47.00%
Consideration adjustment																			$ 6,000,000
Asset consideration															$ 67,000,000				67,000,000
Disposal Group, Disposed of by Sale, Not Discontinued Operations | Cyprus Block 12
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from Divestitures											$ 40,000,000								$ 131,000,000
Midstream
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Goodwill								$ 110,000,000				$ 110,000,000					$ 110,000,000