FAIR VALUE MEASUREMENT - Fair Value Measurement Inputs - Warrants (Details)	Dec. 31, 2021	Dec. 31, 2020
Expected volatility
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants, measurement input	0.838	0.861
Expected term | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants, measurement input	0.4	0.1
Expected term | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants, measurement input	0.5	0.5
Risk-free interest rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants, measurement input	0.004	0.001
Expected dividend yield
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants, measurement input	0	0
Value of underlying share
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants, measurement input	1.34	3.29