Supplemental Information on Oil and Natural Gas Producing Activities (Unaudited) - Results of Operations from Oil and Natural Gas Producing Activities (Unaudited) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Results of Operations for Oil and Gas Producing Activities
Revenues	$ 114,976	$ 266,845
Expenses
Production costs	53,474	110,711
Depreciation and depletion	50,349	146,874
Impairment	218,399	409,574
Total expenses	322,222	667,159
Loss before income taxes	(207,772)	(401,055)
Income tax benefit	(51,750)	(105,477)
Results of operations for oil and natural gas producing activities (excluding corporate overhead and interest costs)	(156,022)	(295,578)
Oil, natural gas and NGL
Results of Operations for Oil and Gas Producing Activities
Revenues	$ 114,450	$ 266,104