REVENUE RECOGNITION (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2018	Dec. 31, 2017
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Oil and gas sales	$ 64,193
Gathering, transportation and processing	2,338
Total operating expenses	41,236
Net income	13,870
Receivables from contracts with customers	37,781	$ 28,549
As Unadjusted
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Oil and gas sales	61,855
Gathering, transportation and processing	0
Total operating expenses	38,898
Net income	13,870
Accounting Standards Update 2014-09 \| ASC 606 Adjustments
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Oil and gas sales	2,338
Gathering, transportation and processing	2,338
Total operating expenses	0
Net income	0
Oil sales
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Oil and gas sales	51,963
Oil sales \| As Unadjusted
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Oil and gas sales	51,963
Oil sales \| Accounting Standards Update 2014-09 \| ASC 606 Adjustments
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Oil and gas sales	0
Natural gas sales
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Oil and gas sales	6,221
Natural gas sales \| As Unadjusted
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Oil and gas sales	5,119
Natural gas sales \| Accounting Standards Update 2014-09 \| ASC 606 Adjustments
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Oil and gas sales	1,102
NGLs sales
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Oil and gas sales	6,009
NGLs sales \| As Unadjusted
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Oil and gas sales	4,773
NGLs sales \| Accounting Standards Update 2014-09 \| ASC 606 Adjustments
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Oil and gas sales	$ 1,236

Amount due from customers or clients, within one year of the balance sheet date (or the normal operating cycle, whichever is longer), for goods or services (including trade receivables) that have been delivered or sold in the normal course of business, reduced to the estimated net realizable fair value by an allowance established by the entity of the amount it deems uncertain of collection.

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Cost incurred related to the gas activities, such as transportation, marketing and processing crude oil, natural gas and refined petroleum products.

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Amount, after deduction of tax, noncontrolling interests, dividends on preferred stock and participating securities; of income (loss) available to common shareholders.

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