SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Summary of Valuation Input for Warrant and Derivative Liabilities (Details)
Jun. 30, 2020
$ / shares
year
May 04, 2020
$ / shares
year
Feb. 11, 2020
$ / shares
Jan. 10, 2020
$ / shares
year
Jan. 06, 2020
$ / shares
May 17, 2019
$ / shares
May 01, 2019
$ / shares
Mar. 18, 2019
$ / shares
Mar. 08, 2019
$ / shares
year
Discount rate                  
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]                  
Derivative liability, measurement input 0.245     0.216         0.293
Conversion price                  
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]                  
Warrants and rights outstanding, measurement input   0.5894              
Conversion price | Short-term Warrants                  
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]                  
Warrants and rights outstanding, measurement input     4.00         4.00  
Conversion price | Long-term Warrants                  
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]                  
Warrants and rights outstanding, measurement input           2.13   2.56  
Conversion price | Exchange Warrants                  
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]                  
Warrants and rights outstanding, measurement input         2.13        
Expected stock price volatility                  
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]                  
Derivative liability, measurement input 0.767     1.039         1.011
Warrants and rights outstanding, measurement input   0.737              
Expected stock price volatility | Short-term Warrants                  
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]                  
Warrants and rights outstanding, measurement input     0.971         1.220  
Expected stock price volatility | Long-term Warrants                  
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]                  
Warrants and rights outstanding, measurement input           0.834   0.852  
Expected stock price volatility | Exchange Warrants                  
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]                  
Warrants and rights outstanding, measurement input         0.873   0.841    
Risk-free interest rate                  
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]                  
Derivative liability, measurement input 0.002     0.016         0.025
Warrants and rights outstanding, measurement input   0.004              
Risk-free interest rate | Short-term Warrants                  
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]                  
Warrants and rights outstanding, measurement input     0.016         0.025  
Risk-free interest rate | Long-term Warrants                  
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]                  
Warrants and rights outstanding, measurement input     0.017     0.022   0.022  
Risk-free interest rate | Exchange Warrants                  
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]                  
Warrants and rights outstanding, measurement input         0.017   0.022    
Expected Term                  
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]                  
Derivative liability, measurement input | year 1.1     2         2
Warrants and rights outstanding, measurement input | year   5              
Price of the underlying common stock                  
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]                  
Derivative liability, measurement input 0.57     0.65         1.99
Warrants and rights outstanding, measurement input   0.50 0.79            
Price of the underlying common stock | Short-term Warrants                  
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]                  
Warrants and rights outstanding, measurement input               2.48  
Price of the underlying common stock | Long-term Warrants                  
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]                  
Warrants and rights outstanding, measurement input     0.79     1.58   2.48  
Price of the underlying common stock | Exchange Warrants                  
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]                  
Warrants and rights outstanding, measurement input         0.58   1.54