Commodity Derivative Financial Instruments - Summary of Fair Value and Classification of Derivative Instruments (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Derivatives Fair Value [Line Items]
Gross Fair Value, Assets	$ 96,294	$ 19,741
Effect of Counterparty Netting, Assets	(16)	(4,343)
Total net carrying value on Balance Sheet, assets	96,278	15,398
Gross Fair Value, Liabilities	16	4,520
Effect of Counterparty Netting, Liabilities	(16)	(4,343)
Total net carrying value on Balance Sheet, liabilities	0	177
Commodity derivative assets
Derivatives Fair Value [Line Items]
Gross Fair Value, Assets	96,294	19,028
Effect of Counterparty Netting, Assets	(16)	(4,238)
Total net carrying value on Balance Sheet, assets	96,278	14,790
Deferred charges and other long-term assets
Derivatives Fair Value [Line Items]
Gross Fair Value, Assets	0	713
Effect of Counterparty Netting, Assets	0	(105)
Total net carrying value on Balance Sheet, assets	0	608
Commodity derivative liabilities
Derivatives Fair Value [Line Items]
Gross Fair Value, Liabilities	16	4,397
Effect of Counterparty Netting, Liabilities	(16)	(4,238)
Total net carrying value on Balance Sheet, liabilities	0	159
Commodity derivative liabilities
Derivatives Fair Value [Line Items]
Gross Fair Value, Liabilities	0	123
Effect of Counterparty Netting, Liabilities	0	(105)
Total net carrying value on Balance Sheet, liabilities	$ 0	$ 18