FAIR VALUE OF MEASUREMENTS AND INVESTMENT SECURITIES - Derivative Liabilities Reported at Fair Value (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrant derivative liability	$ 28,183	$ 52,184
Private placement option derivative liability	33,970	12,094
Level 1
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrant derivative liability	0	0
Private placement option derivative liability	0	0
Total derivative liabilities	0	0
Level 2
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrant derivative liability	0	0
Private placement option derivative liability	0	0
Total derivative liabilities	0	0
Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrant derivative liability	28,183	52,184
Private placement option derivative liability	33,970	12,094
Total derivative liabilities	$ 62,153	$ 64,278