FAIR VALUE MEASUREMENT - Fair Value Measurement Inputs - Purchase Option (Details) (Details)	Mar. 31, 2022	Dec. 31, 2021
Expected volatility
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Purchase option, measurement input	0.925	0.925
Expected term
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Purchase option, measurement input	3.4	3.7
Risk-free interest rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Purchase option, measurement input	0.024	0.011
Weighted average cost of capital
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Purchase option, measurement input	0.400	0.400