DEBT - Carrying and Estimated Fair Values of Financial Instruments (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total, carrying value	$ 514,892
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	198,640	$ 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	98,397	85,694
2021 Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt, carrying value	197,735	$ 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	20,120
Total, fair value	212,120
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	192,000
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	316,154
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	203,461
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	112,693
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	20,120
Warrants, fair value	$ 20,100