FAIR VALUE MEASUREMENTS AND DERIVATIVES - Significant Assumptions used to Determine Fair Value of Public and 2020 PIPE Warrants (Details) - Fair Value, Inputs, Level 2 [Member] - Monte Carlo Model [Member]	Sep. 30, 2021	Dec. 31, 2020
Public Warrants [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Remaining life (in years)	2 years 5 months 19 days	3 years 2 months 19 days
2020 PIPE Warrants [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Remaining life (in years)	3 years 8 months 12 days	4 years 5 months 12 days
Stock Price [Member] | Public Warrants [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Warrants, measurement input	9.97	10.14
Stock Price [Member] | 2020 PIPE Warrants [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Warrants, measurement input	9.97	10.14
Strike Price [Member] | Public Warrants [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Warrants, measurement input	11.50	11.50
Strike Price [Member] | 2020 PIPE Warrants [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Warrants, measurement input	5.75	5.75
Volatility [Member] | Public Warrants [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Warrants, measurement input	63.0	54.0
Volatility [Member] | 2020 PIPE Warrants [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Warrants, measurement input	63.0	54.0
Interest Rate [Member] | Public Warrants [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Warrants, measurement input	0.4	0.2
Interest Rate [Member] | 2020 PIPE Warrants [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Warrants, measurement input	0.7	0.3
Redemption Price [Member] | Public Warrants [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Warrants, measurement input	18.00	18.00
Redemption Price [Member] | 2020 PIPE Warrants [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Warrants, measurement input	14.50	14.50