|**Stock-Based and Other Compensation Plans (Tables)**                              | 12 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
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|**Disclosure of Compensation Related Costs, Share-based Payments [Abstract]**      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
|Stock-based compensation expense                                                   | We recognized total stock-based compensation expense as follows:Year Ended December 31,(millions)201720162015Stock-Based Compensation Expense Included in:General and Administrative Expense$56$62$50Exploration Expense and Other481536Total Stock-Based Compensation Expense$104$77$86Tax Benefit Recognized$(36)$(27)$(30)                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           
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|(millions)                                                                         |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
|Stock-Based Compensation Expense Included in:                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
|General and Administrative Expense                                                 |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
|Exploration Expense and Other                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
|Total Stock-Based Compensation Expense                                             |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
|Tax Benefit Recognized                                                             |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
|**Share-based Compensation Arrangement by Share-based Payment Award [Line Items]** |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
|Schedule of components for Rabbi Trust                                             | Components of that rabbi trust are as follows:December 31,(millions, except share amounts)20172016Rabbi Trust AssetsMutual Fund Investments$57$62Noble Energy Common Stock (at Fair Value)1426Total Rabbi Trust Assets$71$88Liability Under Related Deferred Compensation Plan$71$88Number of Shares of Noble Energy Common Stock Held by Rabbi Trust470,030671,269                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     
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|(millions, except share amounts)                                                   |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
|Rabbi Trust Assets                                                                 |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
|Mutual Fund Investments                                                            |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
|Noble Energy Common Stock (at Fair Value)                                          |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
|Total Rabbi Trust Assets                                                           |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
|Liability Under Related Deferred Compensation Plan                                 |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
|Number of Shares of Noble Energy Common Stock Held by Rabbi Trust                  |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
|Stock Option                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
|**Share-based Compensation Arrangement by Share-based Payment Award [Line Items]** |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
|Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions        | The assumptions used in valuing stock options granted were as follows:Year Ended December 31,(weighted averages)201720162015Expected Term (in Years)6.46.36.0Expected Volatility33.2%32.4%32.6%Risk-Free Rate2.2%1.6%1.4%Expected Dividend Yield0.9%0.7%1.2%Weighted Average Grant-Date Fair Value$13.26$10.10$13.93                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    
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|(weighted averages)                                                                |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
|Expected Term (in Years)                                                           |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
|Expected Volatility                                                                |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
|Risk-Free Rate                                                                     |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
|Expected Dividend Yield                                                            |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
|Weighted Average Grant-Date Fair Value                                             |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
|Share-based Compensation Awards                                                    | Stock option activity was as follows:OptionsWeightedAverageExercisePriceWeightedAverageRemainingContractual TermAggregateIntrinsic Value(per share)(in years)(in millions)Outstanding at December 31, 201615,088,862$43.49Granted1,819,81939.40Exercised(382,882)37.57Forfeited(976,577)43.93Outstanding at December 31, 201715,549,222$43.425.0$6Exercisable at December 31, 201712,101,890$44.984.0$6                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 
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|Outstanding at December 31, 2016                                                   |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
|Granted                                                                            |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
|Exercised                                                                          |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
|Forfeited                                                                          |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
|Outstanding at December 31, 2017                                                   |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
|Exercisable at December 31, 2017                                                   |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
|Restricted Stock                                                                   |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
|**Share-based Compensation Arrangement by Share-based Payment Award [Line Items]** |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
|Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions        | The assumptions used in valuing market based restricted stock awards granted were as follows:Year Ended December 31,201720162015Number of Simulations500,000500,000500,000Expected Volatility35%38%30%Risk-Free Rate1.5%1.0%0.8%                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        
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|                                                                                   | Year Ended December 31,                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 
|                                                                                   | 2017                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    
|Number of Simulations                                                              | 500,000                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 
|Expected Volatility                                                                | 35                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      
|Risk-Free Rate                                                                     | 1.5                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     
|Share-based Compensation Awards                                                    | Restricted stock activity was as follows:Subject to Time                                                         VestingSubject to Market ConditionsNumber of SharesWeightedAverageAward DateFair ValueNumber of SharesWeighted Average Award Date Fair Value(per share)(per share)Outstanding at December 31, 20161,371,780$36.371,502,992$27.43Awarded(1)3,201,50436.26464,60824.25Vested(1)(2,515,383)34.93(219,883)44.61Forfeited(218,164)37.66(535,012)33.12Outstanding at December 31, 20171,839,737$37.211,212,705$25.55(1)During 2017, we awarded approximately1.9 millionshares of restricted stock for the conversion of Clayton Williams Energy shares into Noble Energy shares as part of the Clayton Williams Energy Acquisition. All awards subsequently vested during 2017. These awards are included in the above table. SeeNote3.  Clayton Williams Energy Acquisition.
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|Outstanding at December 31, 2016                                                   |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
|Awarded(1)                                                                         |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
|Vested(1)                                                                          |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
|Forfeited                                                                          |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
|Outstanding at December 31, 2017                                                   |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
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|(1)                                                                                | During 2017, we awarded approximately1.9 millionshares of restricted stock for the conversion of Clayton Williams Energy shares into Noble Energy shares as part of the Clayton Williams Energy Acquisition. All awards subsequently vested during 2017. These awards are included in the above table. SeeNote3.  Clayton Williams Energy Acquisition.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  
|Phantom Share Units (PSUs)                                                         |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
|**Share-based Compensation Arrangement by Share-based Payment Award [Line Items]** |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
|Share-based Compensation Awards                                                    | Phantom unit activity was as follows:Subject to Time                                                         VestingSubject to Market ConditionsNumber of UnitsWeightedAverageAward Date Fair ValueNumber of UnitsWeighted Average Award Date Fair Value(per share)(per share)Outstanding at December 31, 2016712,089$31.65209,504$6.82Vested(13,305)31.65——Forfeited(88,625)31.65(42,021)6.82Outstanding at December 31, 2017610,159$31.65167,483$6.82                                                                                                                                                                                                                                                                                                                                                                                                                                 
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|Outstanding at December 31, 2016                                                   |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
|Vested                                                                             |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
|Forfeited                                                                          |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
|Outstanding at December 31, 2017                                                   |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         

X- DefinitionTabular disclosure of pension and other postretirement benefit arrangements with individual employees, which are generally based on employment contracts between the entity and one or more selected officers or key employees, and which contain a promise by the employer to pay certain amounts at designated future dates, usually including a period after retirement, upon compliance with stipulated requirements. This type of arrangement is distinguished from broader based employee benefit plans as it is usually tailored to the employee. Disclosure also typically includes the amount of related compensation expense recognized during the reporting period and the carrying amount as of the balance sheet date of the related liability.
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