Merger, Acquisitions and Divestitures - Narrative (Details)			1 Months Ended	3 Months Ended		5 Months Ended	12 Months Ended
	Jan. 13, 2017 USD ($) $ / shares shares	Jul. 20, 2015 USD ($) a business $ / shares shares	Dec. 31, 2016 USD ($)	Dec. 31, 2016 USD ($) a well	Jun. 30, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2016 USD ($) a shares	Dec. 31, 2015 USD ($) shares	Dec. 31, 2014 USD ($)	Mar. 31, 2016 USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Stock issued (shares) | shares							0	41,048,240
Sales Proceeds							$ 1,241,000,000	$ 151,000,000	$ 321,000,000
Gain on Divestitures							$ 238,000,000	0	73,000,000
Farm down			35.00%	35.00%			35.00%
Remaining proceeds			$ 40,000,000	$ 40,000,000		$ 0	$ 40,000,000	0
Severance, consulting, investment, advistory, legal and other related merger-related fees							(25,000,000)	81,000,000	0
Revenue since acquisition						181,000,000	457,000,000
Pre-tax loss since acquisition						(120,000,000)	20,000,000
Purchase price adjustment					$ 25,000,000		25,000,000
Goodwill						0		0	620,000,000
Goodwill Impairment							$ 0	779,000,000	0
CONSOL Carried Cost Obligation
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Land held (acres) | a				363,000
Working interest			100.00%	100.00%			100.00%
Cash remitted				$ 213,000,000
Wells Ranch Development Area
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Land exchanged (acres) | a							11,700
Alon A And Alon C
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Farm down			47.00%	47.00%			47.00%
Total consideration value			$ 73,000,000	$ 73,000,000			$ 73,000,000
Asset consideration			67,000,000	67,000,000			67,000,000
Consideration adjustment							$ 6,000,000
Bronco Development Area
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Land sold (acres) | a							13,500
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
Weld County, Colorado
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Consideration expected			$ 505,000,000	$ 505,000,000			$ 505,000,000
MONTANA
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sales Proceeds							152,000,000
Onshore United States properties
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain on Divestitures							(23,000,000)
Tamar Field, Offshore Israel
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain on Divestitures							$ 261,000,000
Farm down			3.50%	3.50%			3.50%
Total consideration value			$ 431,000,000	$ 431,000,000			$ 431,000,000
Asset consideration			316,000,000	316,000,000			316,000,000
Cyprus Block 12
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from farm-out			131,000,000	131,000,000			$ 131,000,000
Total consideration value										$ 131,000,000
Rosetta Resources, Inc
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash paid ($ per share) | $ / shares		$ 36.97
Stock issued (shares) | shares		41,000,000
Consideration transferred		$ 1,529,000,000
Number of Businesses Acquired | business		2
Merger-related costs incurred		$ 81,000,000						81,000,000
Severance, consulting, investment, advistory, legal and other related merger-related fees		66,000,000
Noncash share-based compensation expense		15,000,000
Goodwill		$ 138,000,000				$ 163,000,000		163,000,000
Permian
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash paid			$ 30,000,000
Consideration transferred				$ 300,000,000
Number of wells | well				7
Common Stock | Rosetta Resources, Inc
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Business Combination, stock exchange ratio		0.542
CHINA
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sales Proceeds									186,000,000
Gain on Divestitures									(35,000,000)
Midland Basin | Rosetta Resources, Inc
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Long-term Debt, Fair Value		$ 2,000,000,000
Business Combination, Gas And Oil Area Acquired | a		9,000
Eagle Ford Shale | Rosetta Resources, Inc
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Business Combination, Gas And Oil Area Acquired | a		50,000
Permian | Rosetta Resources, Inc
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Business Combination, Gas And Oil Area Acquired | a		54,000
Delaware Basin | Rosetta Resources, Inc
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Business Combination, Gas And Oil Area Acquired | a		45,000
Rosetta Resources, Inc | Rosetta Resources, Inc
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Severance, consulting, investment, advistory, legal and other related merger-related fees								$ 37,000,000
Subsequent Event | Clayton Williams Energy
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash and equity paid	$ 2,700,000,000
Shares issued per share | shares	2.7874
Cash paid ($ per share) | $ / shares	$ 34.75
Stock issued (shares) | shares	55,000,000
Cash paid	$ 665,000,000
Consideration transferred	3,200,000,000
Debt assumed	$ 500,000,000
Onshore United States properties
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sales Proceeds									135,000,000
Gain on Divestitures									$ (36,000,000)