FAIR VALUE MEASUREMENTS OF CERTAIN LIABILITIES - Quantitative Inputs (Details) - Warrant liabilities - Fair Value, Inputs, Level 3	Jun. 30, 2021	Dec. 31, 2020
Expected volatility
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrant liability, measurement input	1.0000	0.8500
Risk-free interest rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrant liability, measurement input	0.0027	0.0018
Expected remaining term (years)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrant liability, measurement input	2.23	2.73