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LONG-TERM DEBT - Schedule of Debt (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019	Oct. 21, 2019
Debt Instrument [Line Items]
Principal Balance	$ 1,047,489	$ 1,127,733
Unamoritzed debt discounts and premiums	3,244	4,860
Unamortized debt issuance costs	(10,450)	(14,432)
Total debt	1,040,282	1,118,161
Less current portion of long-term debt	(65,000)	0
Total long-term debt	975,282	1,118,161
Second Lien Notes due 2023 \| Line of Credit
Debt Instrument [Line Items]
Principal Balance	327,489	417,733
Unsecured VEN Bakken Note
Debt Instrument [Line Items]
Principal Balance	130,000	130,000
Revolving Credit Facility
Debt Instrument [Line Items]
Principal Balance	590,000	580,000
Revolving Credit Facility \| Other Noncurrent Assets, Net
Debt Instrument [Line Items]
Unamortized debt issuance costs	$ (9,300)	$ (9,800)
Revolving Credit Facility \| Second Lien Notes due 2023
Debt Instrument [Line Items]
Total debt			$ 200,000