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Revenue from Contracts with Customers Disaggregation of oil, gas, and NGL production revenue (Details) - USD ($) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016
Segment Reporting Information [Line Items] |  |  |  |  |  |
Revenue from Contract with Customer, Including Assessed Tax | $ 1,636,357 | [1] | $ 1,253,783 | [2] | $ 1,178,426 | [3]
Concentration Risk, Percentage | 100.00% | [1] | 100.00% | [2] | 100.00% | [3]
Revenue, Remaining Performance Obligation, Amount | $ 0 |  |  |  |  |
Permian Region [Member] |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |
Revenue from Contract with Customer, Including Assessed Tax | 1,064,607 | [1] | $ 482,060 | [2] | $ 134,806 | [3]
South Texas & Gulf Coast [Member] |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |
Revenue from Contract with Customer, Including Assessed Tax | 514,514 | [1] | 610,485 | [2] | 723,963 | [3]
Rocky Mountain Region [Member] |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |
Revenue from Contract with Customer, Including Assessed Tax | $ 57,236 | [1] | $ 161,238 | [2] | $ 319,657 | [3]
Sales Revenue, Net [Member] | Geographic Concentration Risk [Member] | Permian Region [Member] |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |
Concentration Risk, Percentage | 65.00% | [1] | 38.00% | [2] | 11.00% | [3]
Sales Revenue, Net [Member] | Geographic Concentration Risk [Member] | South Texas & Gulf Coast [Member] |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |
Concentration Risk, Percentage | 32.00% | [1] | 49.00% | [2] | 62.00% | [3]
Sales Revenue, Net [Member] | Geographic Concentration Risk [Member] | Rocky Mountain Region [Member] |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |
Concentration Risk, Percentage | 3.00% | [1] | 13.00% | [2] | 27.00% | [3]
Oil production revenue [Member] |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |
Revenue from Contract with Customer, Including Assessed Tax | $ 1,065,676 | [1] | $ 654,250 | [2] | $ 611,838 | [3]
Oil production revenue [Member] | Permian Region [Member] |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |
Revenue from Contract with Customer, Including Assessed Tax | 938,004 |  | 419,732 |  | 117,399 |
Oil production revenue [Member] | South Texas & Gulf Coast [Member] |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |
Revenue from Contract with Customer, Including Assessed Tax | 72,821 |  | 82,674 |  | 189,313 |
Oil production revenue [Member] | Rocky Mountain Region [Member] |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |
Revenue from Contract with Customer, Including Assessed Tax | 54,851 |  | 151,844 |  | 305,126 |
Gas production revenue [Member] |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |
Revenue from Contract with Customer, Including Assessed Tax | 354,450 | [1] | 369,410 | [2] | 337,288 | [3]
Gas production revenue [Member] | Permian Region [Member] |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |
Revenue from Contract with Customer, Including Assessed Tax | 125,603 |  | 61,781 |  | 17,315 |
Gas production revenue [Member] | South Texas & Gulf Coast [Member] |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |
Revenue from Contract with Customer, Including Assessed Tax | 227,252 |  | 301,780 |  | 308,829 |
Gas production revenue [Member] | Rocky Mountain Region [Member] |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |
Revenue from Contract with Customer, Including Assessed Tax | 1,595 |  | 5,849 |  | 11,144 |
NGL production revenue [Member] |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |
Revenue from Contract with Customer, Including Assessed Tax | 216,231 | [1] | 230,123 | [2] | 229,300 | [3]
NGL production revenue [Member] | Permian Region [Member] |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |
Revenue from Contract with Customer, Including Assessed Tax | 1,000 |  | 547 |  | 92 |
NGL production revenue [Member] | South Texas & Gulf Coast [Member] |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |
Revenue from Contract with Customer, Including Assessed Tax | 214,441 |  | 226,031 |  | 225,821 |
NGL production revenue [Member] | Rocky Mountain Region [Member] |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |
Revenue from Contract with Customer, Including Assessed Tax | $ 790 |  | $ 3,545 |  | $ 3,387 |
[1] | Note: Amounts may not calculate due to rounding.
[2] | Note: Amounts may not calculate due to rounding.
[3] | Note: Amounts may not calculate due to rounding.

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