COMMON STOCK WARRANT LIABILITY - Level 3 Fair Value Inputs (Details)	Sep. 30, 2021 year $ / shares	Jul. 23, 2021 year $ / shares	Feb. 28, 2021 $ / shares	Dec. 31, 2020 rate	Sep. 30, 2017 $ / shares
Class of Warrant or Right [Line Items]
Warrant exercise price (in dollars per share) | $ / shares		$ 11.50	$ 1.94		$ 1.94
Level 3 | Private Warrants, Non-Contingent
Class of Warrant or Right [Line Items]
Warrant exercise price (in dollars per share) | $ / shares	$ 18.92	18.44
Level 3 | Vesting Tranche One | Private Warrants, Contingent
Class of Warrant or Right [Line Items]
Warrant volume-weighted average trading price (in dollars per share) | $ / shares	20.00
Warrant exercise price (in dollars per share) | $ / shares	0	18.16
Level 3 | Vesting Tranche Two | Private Warrants, Contingent
Class of Warrant or Right [Line Items]
Warrant volume-weighted average trading price (in dollars per share) | $ / shares	25.00
Warrant exercise price (in dollars per share) | $ / shares	18.78	18.07
Level 3 | Vesting Tranche Three | Private Warrants, Contingent
Class of Warrant or Right [Line Items]
Warrant volume-weighted average trading price (in dollars per share) | $ / shares	30.00
Warrant exercise price (in dollars per share) | $ / shares	$ 18.60	$ 17.92
Volatility
Class of Warrant or Right [Line Items]
Warrant measurement input				0.5000
Volatility | Level 3 | Private Warrants, Non-Contingent
Class of Warrant or Right [Line Items]
Warrant measurement input | year	0.7500	0.8000
Volatility | Level 3 | Private Warrants, Contingent
Class of Warrant or Right [Line Items]
Warrant measurement input | year	0.7500	0.8000
Expected term (in years) | Level 3 | Private Warrants, Non-Contingent
Class of Warrant or Right [Line Items]
Warrant measurement input | year	4.8	5.0
Expected term (in years) | Level 3 | Private Warrants, Contingent
Class of Warrant or Right [Line Items]
Warrant measurement input | year	4.8	5.0
Risk-free rate | Level 3 | Private Warrants, Non-Contingent
Class of Warrant or Right [Line Items]
Warrant measurement input | year	0.0094	0.0072
Risk-free rate | Level 3 | Private Warrants, Contingent
Class of Warrant or Right [Line Items]
Warrant measurement input | year	0.0094	0.0072
Expected dividend rate
Class of Warrant or Right [Line Items]
Warrant measurement input | rate				0.0000
Expected dividend rate | Level 3 | Private Warrants, Non-Contingent
Class of Warrant or Right [Line Items]
Warrant measurement input | year	0	0
Expected dividend rate | Level 3 | Private Warrants, Contingent
Class of Warrant or Right [Line Items]
Warrant measurement input | year	0	0