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Derivatives - Narrative (Details) bbl in Thousands, $ in Thousands | 3 Months Ended | 9 Months Ended | 12 Months Ended
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Dec. 31, 2018 USD ($) institution $ / Unit | Sep. 30, 2018 USD ($) | Jun. 30, 2018 USD ($) | Mar. 31, 2018 USD ($) | Dec. 31, 2017 USD ($) | Sep. 30, 2017 USD ($) | Jun. 30, 2017 USD ($) | Mar. 31, 2017 USD ($) | Dec. 31, 2016 USD ($) | Oct. 01, 2016 USD ($) | Dec. 31, 2018 USD ($) institution $ / Unit bbl | Dec. 31, 2017 USD ($)
Derivative Instruments and Hedging Activities Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Loss (gain) on derivative contracts | $ (42,600) | $ 11,300 | $ 30,100 | $ 18,300 | $ 21,900 | $ 11,700 | $ (23,500) | $ (34,200) |  |  |  |
Number of counterparties to open derivative contracts | institution | 4 |  |  |  |  |  |  |  |  |  | 4 |
Commodity Derivatives |  |  |  |  |  |  |  |  |  |  |  |
Derivative Instruments and Hedging Activities Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Loss (gain) on derivative contracts |  |  |  |  |  |  |  |  |  |  | $ 17,200 | $ (24,100)
Payments for (proceeds from) settlement of derivative contracts |  |  |  |  |  |  |  |  |  |  | 35,300 | (7,300)
Payment for early settlements |  |  |  |  |  |  |  |  |  |  | 800 |
Successor |  |  |  |  |  |  |  |  |  |  |  |
Derivative Instruments and Hedging Activities Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Loss (gain) on derivative contracts |  |  |  |  |  |  |  |  | $ 25,652 |  | 17,155 | (24,090)
Payments for (proceeds from) settlement of derivative contracts |  |  |  |  |  |  |  |  | (7,698) |  | $ 35,325 | $ (7,260)
Successor | Commodity Derivatives |  |  |  |  |  |  |  |  |  |  |  |
Derivative Instruments and Hedging Activities Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Loss (gain) on derivative contracts |  |  |  |  |  |  |  |  | 25,700 |  |  |
Payments for (proceeds from) settlement of derivative contracts |  |  |  |  |  |  |  |  | $ (7,700) |  |  |
Predecessor |  |  |  |  |  |  |  |  |  |  |  |
Derivative Instruments and Hedging Activities Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Loss (gain) on derivative contracts |  |  |  |  |  |  |  |  |  | $ 4,823 |  |
Payments for (proceeds from) settlement of derivative contracts |  |  |  |  |  |  |  |  |  | (72,608) |  |
Predecessor | Commodity Derivatives |  |  |  |  |  |  |  |  |  |  |  |
Derivative Instruments and Hedging Activities Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Loss (gain) on derivative contracts |  |  |  |  |  |  |  |  |  | 4,800 |  |
Payments for (proceeds from) settlement of derivative contracts |  |  |  |  |  |  |  |  |  | (72,600) |  |
Derivative, cash received on early settlement |  |  |  |  |  |  |  |  |  | $ (17,900) |  |
2018 Production |  |  |  |  |  |  |  |  |  |  |  |
Derivative Instruments and Hedging Activities Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Notional (MMcf) | bbl |  |  |  |  |  |  |  |  |  |  | 9 |
Strike price (in dollars per unit) | $ / Unit | 56.12 |  |  |  |  |  |  |  |  |  | 56.12 |
2019 Production |  |  |  |  |  |  |  |  |  |  |  |
Derivative Instruments and Hedging Activities Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Notional (MMcf) | bbl |  |  |  |  |  |  |  |  |  |  | 5 |
Strike price (in dollars per unit) | $ / Unit | 54.29 |  |  |  |  |  |  |  |  |  | 54.29 |

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