Derivative Instruments - Fair value gains (losses) (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Summary of realized and unrealized gains (losses) on derivative instruments
Commodity derivative fair value gains (losses)	$ 565,833	$ (77,368)
Revenue
Summary of realized and unrealized gains (losses) on derivative instruments
Commodity derivative fair value gains (losses)	$ 565,833	$ (77,368)

Amount of realized and unrealized gain (loss) of derivative instruments not designated or qualifying as hedging instruments.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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