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Acquisitions and Divestitures - Acquisitions (Details) a in Thousands, $ in Thousands |  |  |  |  | 3 Months Ended | 12 Months Ended
--- | --- | --- | --- | --- | --- | ---
Dec. 08, 2017 shares | Dec. 01, 2017 USD ($) a | Apr. 25, 2017 USD ($) | Dec. 01, 2016 USD ($) a | Dec. 31, 2017 USD ($) | Sep. 30, 2017 USD ($) | Jun. 30, 2017 USD ($) | Mar. 31, 2017 USD ($) | Dec. 31, 2016 USD ($) | Sep. 30, 2016 USD ($) | Jun. 30, 2016 USD ($) | Mar. 31, 2016 USD ($) | Dec. 31, 2017 USD ($) | Dec. 31, 2016 USD ($) | Dec. 31, 2015 USD ($)
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Acquisitions of oil and gas properties |  |  |  |  |  |  |  |  |  |  |  |  | $ 61,874 | $ 781,522 | $ 28,817
Total revenues |  |  |  |  | $ 404,469 | $ 304,748 | $ 254,091 | $ 285,116 | $ 217,991 | $ 177,311 | $ 179,080 | $ 130,283 | 1,248,424 | 704,665 | 789,735
Operating income |  |  |  |  | $ 86,103 | $ 32,394 | $ 5,379 | $ 20,092 | $ (1,702) | $ (25,702) | $ (28,214) | $ (75,215) | 143,968 | (130,833) | (114,164)
Permian Basin Acquisition |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Acquisitions of oil and gas properties |  | $ 549,800 |  |  |  |  |  |  |  |  |  |  |  |  |
Shares issued as consideration (shares) | shares | 46,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Acres acquired | a |  | 22 |  |  |  |  |  |  |  |  |  |  |  |  |
MIdstream Assets Acquisition |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Consideration transferred |  |  | $ 12,700 |  |  |  |  |  |  |  |  |  |  |  |
Installment notes payable |  |  | 4,900 |  |  |  |  |  |  |  |  |  |  |  |
Fair value of assets acquired |  |  | $ 12,700 |  |  |  |  |  |  |  |  |  |  |  |
Williston Basin Acquisition |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Consideration transferred |  |  |  | $ 764,300 |  |  |  |  |  |  |  |  |  |  |
Acres acquired | a |  |  |  | 55 |  |  |  |  |  |  |  |  |  |  |
Recognized identifiable assets acquired |  |  |  | $ 764,300 |  |  |  |  |  |  |  |  |  |  |
Total revenues |  |  |  |  |  |  |  |  |  |  |  |  |  | 14,600 |
Operating income |  |  |  |  |  |  |  |  |  |  |  |  |  | 5,900 |
Acquisition costs |  |  |  |  |  |  |  |  |  |  |  |  |  | 300 |
Forge Energy | Permian Basin Acquisition |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Security Deposit |  | $ 47,300 |  |  |  |  |  |  |  |  |  |  |  |  |
Several Acreage and Producing Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Acquisitions of oil and gas properties |  |  |  |  |  |  |  |  |  |  |  |  | $ 6,100 | $ 15,800 | $ 28,817

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