SHARE-BASED COMPENSATION - Schedule of Stock Option Activity (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2022	Dec. 31, 2021
Shares
Beginning balance (in shares)	69,244
Granted (in shares)	6,896
Exercised (in shares)	(338)
Forfeited (in shares)	(2,416)
Expired (in shares)	(412)
Ending balance (in shares)	72,974	69,244
Weighted-Average Exercise Price
Beginning balance (in dollars per share)	$ 1.84
Granted (in dollars per share)	1.79
Exercised (in dollars per share)	0.76
Forfeited (in dollars per share)	2.24
Expired (in dollars per share)	2.22
Ending balance (in dollars per share)	$ 1.83	$ 1.84
Aggregate Intrinsic Value
Beginning balance	$ 113,908
Ending balance	$ 22,419	$ 113,908
Weighted-Average Remaining Contractual Life (In Years)	7 years 9 months 18 days	8 years 2 months 12 days