FAIR VALUE OF FINANCIAL INSTRUMENTS - Summary of recurring fair value measurements (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total recurring fair value measurements	$ (6,869)	$ (841)
Oil and natural gas derivative swap contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Recurring fair value measurements	(3,932)	(2,923)
Oil and natural gas derivative collar contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Recurring fair value measurements	301	4,047
Net settlement provisions under ARM sales agreement
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Recurring fair value measurements	3,238
Second Lien Term Loan conversion features
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Recurring fair value measurements		(1,965)
Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total recurring fair value measurements	0	0
Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) | Oil and natural gas derivative swap contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Recurring fair value measurements	0	0
Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) | Oil and natural gas derivative collar contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Recurring fair value measurements	0	0
Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) | Net settlement provisions under ARM sales agreement
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Recurring fair value measurements	0
Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) | Second Lien Term Loan conversion features
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Recurring fair value measurements		0
Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total recurring fair value measurements	(3,631)	1,124
Significant Other Observable Inputs (Level 2) | Oil and natural gas derivative swap contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Recurring fair value measurements	(3,932)	(2,923)
Significant Other Observable Inputs (Level 2) | Oil and natural gas derivative collar contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Recurring fair value measurements	301	4,047
Significant Other Observable Inputs (Level 2) | Net settlement provisions under ARM sales agreement
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Recurring fair value measurements	0
Significant Other Observable Inputs (Level 2) | Second Lien Term Loan conversion features
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Recurring fair value measurements		0
Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total recurring fair value measurements	(3,238)	(1,965)
Significant Unobservable Inputs (Level 3) | Oil and natural gas derivative swap contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Recurring fair value measurements	0	0
Significant Unobservable Inputs (Level 3) | Oil and natural gas derivative collar contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Recurring fair value measurements	0	0
Significant Unobservable Inputs (Level 3) | Net settlement provisions under ARM sales agreement
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Recurring fair value measurements	$ 3,238
Significant Unobservable Inputs (Level 3) | Second Lien Term Loan conversion features
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Recurring fair value measurements		$ (1,965)