DEBT - Carrying and Estimated Fair Values of Financial Instruments (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total, carrying value	$ 522,023
First Lien Note Facility, net of unamortized discount
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt, carrying value	198,801	$ 198,324
Second Lien Note Facility, net of unamortized discount
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt, carrying value	103,571	85,694
2021 Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt, carrying value	197,927	$ 197,363
Markets for Identical Item (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Warrants, fair value	0
Total, fair value	0
Markets for Identical Item (Level 1) | First Lien Note Facility, net of unamortized discount
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt, fair value	0
Markets for Identical Item (Level 1) | Second Lien Note Facility, net of unamortized discount
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt, fair value	0
Markets for Identical Item (Level 1) | 2021 Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt, fair value	0
Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Warrants, fair value	21,724
Total, fair value	211,224
Significant Other Observable Inputs (Level 2) | First Lien Note Facility, net of unamortized discount
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt, fair value	0
Significant Other Observable Inputs (Level 2) | Second Lien Note Facility, net of unamortized discount
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt, fair value	0
Significant Other Observable Inputs (Level 2) | 2021 Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt, fair value	189,500
Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Warrants, fair value	0
Total, fair value	319,731
Significant Unobservable Inputs (Level 3) | First Lien Note Facility, net of unamortized discount
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt, fair value	202,512
Significant Unobservable Inputs (Level 3) | Second Lien Note Facility, net of unamortized discount
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt, fair value	117,219
Significant Unobservable Inputs (Level 3) | 2021 Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt, fair value	0
2017 Warrants | Common Stock
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Warrants, carrying value	21,724
Warrants, fair value	$ 21,700