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Impairment (Details) - USD ($)
$ in Thousands
3 Months Ended 12 Months Ended
Dec. 31, 2020
Dec. 31, 2020
Dec. 31, 2019
Schedule of Impaired Long-Lived Assets Held and Used and Intangible Assets [Line Items]      
Full cost pool ceiling impairments $ 2,600 $ 218,399 $ 409,574
Asset impairment charges   256,399 409,574
Impairment   256,399 409,574
Other      
Schedule of Impaired Long-Lived Assets Held and Used and Intangible Assets [Line Items]      
Asset impairment charges   38,000 0
Impairment   $ 38,000 $ 0