STOCK-BASED COMPENSATION AND BENEFIT PLAN - Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Stock Options
Outstanding beginning balance (in shares)	13,312,835
Granted (in shares)	4,088,450
Exercised (in shares)	(280,260)
Expired (in shares)	(25,074)
Canceled and forfeited (in shares)	(218,175)
Outstanding ending balance (in shares)	16,877,776	13,312,835
Options exercisable at end of period (in shares)	7,898,693
Weighted Average Exercise Price
Outstanding beginning balance (in dollars per share)	$ 4.20
Granted (in dollars per share)	1.68
Exercised (in dollars per share)	0.50
Expired (in dollars per share)	13.67
Canceled and forfeited (in dollars per share)	6.28
Outstanding ending balance (in dollars per share)	3.61	$ 4.20
Options exercisable at end of period, weighted-average exercise price (in dollars per share)	$ 5.94
Weighted-Average Contractual Life (years)
Options outstanding, weighted-average remaining contractual life (in years)	7 years 8 months 8 days	7 years 3 months 7 days
Options exercisable at end of period, weighted-average remaining contractual life (in years)	6 years 18 days
Options outstanding, aggregate intrinsic value	$ 5,655	$ 0