NET LOSS PER SHARE - Loss per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
EPS Numerator:
Net loss	$ (17,914)	$ (29,744)	$ (66,894)
EPS Denominator-Basic:
Weighted-average common shares outstanding, Basic	170,492	168,754	167,400
EPS Denominator-Diluted:
Weighted-average common shares outstanding, Diluted	170,492	168,754	167,400
Net income (loss) per share
Earnings Per Share, Basic	$ (0.11)	$ (0.18)	$ (0.40)
Earnings Per Share, Diluted	$ (0.11)	$ (0.18)	$ (0.40)