SUPPLEMENTAL OIL AND GAS INFORMATION (UNAUDITED) - Average Prices (Details)	12 Months Ended
	Dec. 31, 2020 $ / bbl $ / Mcf	Dec. 31, 2019 $ / bbl $ / Mcf	Dec. 31, 2018 $ / bbl $ / Mcf
Natural Gas
Oil and Gas, Average Sale Price and Production Cost Per Unit [Line Items]
Average sales price | $ / Mcf	1.64	2.35	2.58
Crude Oil
Oil and Gas, Average Sale Price and Production Cost Per Unit [Line Items]
Average sales price	32.53	55.80	65.21
Natural Gas Liquids
Oil and Gas, Average Sale Price and Production Cost Per Unit [Line Items]
Average sales price	0	0	21.64