CONTINGENTLY REDEEMABLE CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS’ (DEFICIT) EQUITY - Warrant Activity (Details) - Stock warrants - $ / shares	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Common Stock Warrants
Shares
Outstanding at beginning of period (in shares)	8,000,000	8,000,000
Granted (in shares)		0
Transferred from preferred stock warrant (in shares)		4,000,000
Exercised (in shares)		0
Forfeited / cancelled (in shares)		0
Outstanding at end of period (in shares)		12,000,000	8,000,000
Exercisable (in shares)		12,000,000
Weighted Average Exercise Price
Outstanding at beginning of period (in USD per share)	$ 6.00	$ 6.00
Granted (in USD per share)		0	$ 4.30	$ 2.30
Transferred from preferred stock warrant (in USD per share)		9.09
Exercised (in USD per share)		0
Forfeited / cancelled (in USD per share)		(5.66)
Outstanding at end of period (in USD per share)		6.84	$ 6.00
Exercisable (USD per share)		$ 6.84
Weighted Average Remaining Contractual Term
Outstanding (in years)	7 years 7 months 6 days	7 years
Exercisable (in years)		7 years
Preferred Stock Warrants
Shares
Outstanding at beginning of period (in shares)	4,000,000	4,000,000
Granted (in shares)		0
Exercised (in shares)		0
Forfeited / cancelled (in shares)		(4,000,000)
Outstanding at end of period (in shares)		0	4,000,000
Exercisable (in shares)		0
Weighted Average Exercise Price
Outstanding at beginning of period (in USD per share)	$ 9.09	$ 9.09
Granted (in USD per share)		0
Exercised (in USD per share)		0
Forfeited / cancelled (in USD per share)		(9.09)
Outstanding at end of period (in USD per share)		0	$ 9.09
Exercisable (USD per share)		$ 0