|**Debt (Tables)**                                                        | 3 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            
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|**Debt Disclosure [Abstract]**                                           |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           
|Schedule of Debt                                                         | Debt consists of the following:March 31, 2019December 31, 2018(millions, except percentages)DebtInterest RateDebtInterest RateRevolving Credit Facility, due March 9, 2023(1)$——%$——%Noble Midstream Services Revolving Credit Facility, due March 9, 2023(2)2303.66%603.67%Noble Midstream Services Term Loan Credit Facility, due July 31, 20215003.41%5003.42%Senior Notes and Debentures5,892(3)5,892(3)Finance Lease Obligations(4)215—%223—%Total6,8376,675Net Unamortized Discounts and Debt Issuance Costs(58)(60)Total Debt6,7796,615Less Amounts Due Within One YearFinance Lease Obligations(4)(41)(41)Long-Term Debt Due After One Year$6,738$6,574(1)As ofMarch 31, 2019andDecember 31, 2018, the Revolving Credit Facility had $4.0billion of capacity and the entire amount was available for borrowing.(2)As ofMarch 31, 2019andDecember 31, 2018, the Noble Midstream Services Revolving Credit Facility had $800million of capacity. Amounts available for borrowing at totaled $570million and $740million, respectively.(3)The Senior Notes and Debentures have weighted average interest rates of5.01%for bothMarch 31, 2019andDecember 31, 2018.(4)SeeNote8. Leases.
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|                                                                         | March 31, 2019                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            
|(millions, except percentages)                                           | Debt                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      
|Revolving Credit Facility, due March 9, 2023(1)                          | $                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
|Noble Midstream Services Revolving Credit Facility, due March 9, 2023(2) | 230                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
|Noble Midstream Services Term Loan Credit Facility, due July 31, 2021    | 500                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
|Senior Notes and Debentures                                              | 5,892                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     
|Finance Lease Obligations(4)                                             | 215                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
|Total                                                                    | 6,837                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     
|Net Unamortized Discounts and Debt Issuance Costs                        | (58                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
|Total Debt                                                               | 6,779                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     
|Less Amounts Due Within One Year                                         |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           
|Finance Lease Obligations(4)                                             | (41                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
|Long-Term Debt Due After One Year                                        | $                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
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|(1)                                                                      | As ofMarch 31, 2019andDecember 31, 2018, the Revolving Credit Facility had $4.0billion of capacity and the entire amount was available for borrowing.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     
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|(2)                                                                      | As ofMarch 31, 2019andDecember 31, 2018, the Noble Midstream Services Revolving Credit Facility had $800million of capacity. Amounts available for borrowing at totaled $570million and $740million, respectively.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        
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|(3)                                                                      | The Senior Notes and Debentures have weighted average interest rates of5.01%for bothMarch 31, 2019andDecember 31, 2018.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   

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