FAIR VALUE OF FINANCIAL INSTRUMENTS - Reconciliation of changes in the fair value of the Company's Level 3 financial assets and liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning	$ (1,965)	$ (72,937)
Transferred to equity		223
Fair value of the converted portion of the embedded derivatives associated with the Second Lien Term Loan	2,300	12,406
Change in fair value of embedded derivatives and derivative liabilities	(3,573)	58,343
Balance, ending	(3,238)	(1,965)
Warrant Liability
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning	0	(223)
Transferred to equity		223
Fair value of the converted portion of the embedded derivatives associated with the Second Lien Term Loan		0
Change in fair value of embedded derivatives and derivative liabilities		0
Balance, ending		0
Firm Takeaway and Pricing Agreement Net Settlement Provisions
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning	0
Fair value of the converted portion of the embedded derivatives associated with the Second Lien Term Loan	0
Change in fair value of embedded derivatives and derivative liabilities	(3,238)
Balance, ending	(3,238)	0
Second Lien Term Loan conversion features
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning	(1,965)	(72,714)
Transferred to equity		0
Fair value of the converted portion of the embedded derivatives associated with the Second Lien Term Loan	2,300	12,406
Change in fair value of embedded derivatives and derivative liabilities	(335)	58,343
Balance, ending	$ 0	$ (1,965)