SUPPLEMENTAL INFORMATION - NATURAL GAS AND CRUDE OIL PROPERTIES Index price of reserves (Details) - USD ($)		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Crude Oil [Member]
oil and gas index price for reserves [Line Items]
oil and gas index price for reserves	[1]	$ 55.69	$ 65.56	$ 51.34
Natural Gas [Member]
oil and gas index price for reserves [Line Items]
oil and gas index price for reserves	[1]	2.58	3.10	2.98
Natural Gas Liquids (Bbls)
oil and gas index price for reserves [Line Items]
oil and gas index price for reserves	[1]	$ 55.69	$ 65.56	$ 51.34

[1] Per SEC rules, the pricing used to prepare the proved reserves is based on the unweighted arithmetic average of the first of the month prices for the preceding 12 months.