Merger, Acquisitions and Divestitures - Narrative (Details) a in Thousands, $ in Millions		1 Months Ended	5 Months Ended	12 Months Ended
	Jul. 20, 2015 USD ($) a business shares	Oct. 31, 2013 USD ($) a	Dec. 31, 2015 USD ($)	Dec. 31, 2015 USD ($) shares	Dec. 31, 2014 USD ($) shares	Dec. 31, 2013 USD ($)	Nov. 30, 2015 USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Shares of Noble Energy common stock issued to Rosetta shareholders | shares				41,048,240	0
Severance, consulting, investment, advistory, legal and other related merger-related fees				$ 81	$ 0	$ 0
Goodwill Impairment				779	0	0
Land Exchanged In Agreement (in acres) | a		50
Cash Received For Reimbursement of Capital Expenditures and Other Normal Closing Adjustments		$ 105
Proceeds from Divestitures				151	$ 321	327
Alon A And Alon C
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Group, Including Discontinued Operations, Adjustment of Costs Offsetting Consideration							$ 6
Ownership interest in equity method investments (in hundredths)							47.00%
Total consideration value							$ 73
North Sea Assets
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain on Sale, Net of Tax						65
Proceeds from Divestitures						$ 56
Rosetta Resources, Inc
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Shares of Noble Energy common stock issued to Rosetta shareholders | shares	41,000,000
Number of Businesses Acquired | business	2
Merger-related costs incurred				81
Severance, consulting, investment, advistory, legal and other related merger-related fees				66
Noncash share-based compensation expense				15
Revenue since acquisition			$ 181
Pre-tax loss since acquisition			120
Goodwill Impairment			$ 163
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
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
Business Combination, Gas And Oil Area Acquired | a	9
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
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
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
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