STANDARDIZED MEASURE OF DISCOUNTED FUTURE NET CASH FLOWS RELATING TO PROVED OIL, NATURAL GAS AND NATURAL GAS LIQUIDS RESERVES (UNAUDITED) (Narrative) (Details)	12 Months Ended
	Dec. 31, 2018 $ / MMBTU $ / item	Dec. 31, 2017 $ / MMBTU $ / item	Dec. 31, 2016 $ / MMBTU $ / item
Discounted Future Net Cash Flows Relating to Proved Oil and Gas Reserves [Line Items]
Future net cash flows, annual discount rate	10.00%	10.00%	10.00%
Oil
Discounted Future Net Cash Flows Relating to Proved Oil and Gas Reserves [Line Items]
Prices utilized in calculating total estimated proved reserves | $ / item	65.56	51.34	42.75
Natural Gas [Member]
Discounted Future Net Cash Flows Relating to Proved Oil and Gas Reserves [Line Items]
Prices utilized in calculating total estimated proved reserves | $ / MMBTU	3.10	2.976	2.481