SUPPLEMENTARY INFORMATION ON OIL AND NATURAL GAS EXPLORATION, DEVELOPMENT - Results of Operations for Oil and Natural Gas Producing Activities (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Supplemental Oil And Gas Reserve Information [Abstract]
Revenues	$ 66,063,000	$ 70,216,000
Production costs	(16,127,000)	(13,843,000)
Production taxes	(3,302,000)	(3,709,000)
Accretion of asset retirement obligation	(433,000)	(85,000)
Depletion, depreciation and amortization	(33,071,000)	(25,159,000)
Full cost ceiling impairment	(228,324,000)	0
Total	$ (215,194,000)	$ 27,420,000