Investment in Laramie Energy, LLC - Additional Information (Details) - USD ($)	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Schedule of Equity Method Investments [Line Items]
Depreciation, depletion, and amortization	$ 21,283,000	$ 20,957,000
Unrealized gain (loss) on derivative contracts	$ (28,351,000)	(5,255,000)
Laramie Energy Company
Schedule of Equity Method Investments [Line Items]
Ownership interest in Laramie Energy, LLC	46.00%
Equity method investments, fair value	$ 1,874,000		$ 46,905,000
Equity method investment, aggregate cost	47,200,000
Impairment of our investment in Laramie Energy	45,294,000
Depreciation, depletion, and amortization	9,300,000	21,400,000
Unrealized gain (loss) on derivative contracts	2,400,000	$ 2,700,000
Revolving Credit Facility | Laramie Energy Company
Schedule of Equity Method Investments [Line Items]
Credit facility, maximum borrowing amount	400,000,000
Asset borrowing base	220,000,000
Balance outstanding on the revolving credit facility	$ 190,000,000.0