FAIR VALUE MEASUREMENTS (Tables)

9 Months Ended

Sep. 30, 2019

FAIR VALUE MEASUREMENTS [Abstract]

Fair Value Hierarchy for Assets and Liabilities Measured at Fair Value on Recurring Basis

			Fair Value Measurements
			at the End of the Reporting Period
			Quoted Prices
			in Active		Significant
			Markets for		Other		Significant
			Identical		Observable		Unobservable
			Assets		Inputs		Inputs
	Fair Value		(Level 1)		(Level 2)		(Level 3)
As of September 30, 2019:
Assets:
Oil, natural gas and natural gas liquids derivatives	$	10,678	$	—	$	10,678	$	—
As of December 31, 2018:
Assets:
Oil, natural gas and natural gas liquids derivatives	$	26,613	$	—	$	26,613	$	—
Equity securities		47,082		47,082		—		—
	$	73,695	$	47,082	$	26,613	$	—
Liabilities:
Oil, natural gas and natural gas liquids derivatives	$	3,827	$	—	$	3,827	$	—

Fair Value Hierarchy for Assets and Liabilities Measured at Fair Value on Nonrecurring Basis

			Fair Value Measurements
			Quoted Prices
			in Active		Significant
			Markets for		Other		Significant
			Identical		Observable		Unobservable
			Assets		Inputs		Inputs		Total
	Fair Value		(Level 1)		(Level 2)		(Level 3)		Losses
Nine Months Ended September 30, 2019:
Long–lived assets held and used	$	9,371	$	—	$	—	$	9,371	$	11,657