NET INCOME (LOSS) PER SHARE - Tabular Disclosure (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Basic
Net income (loss)	$ 22,579	$ 7,775	$ (39,164)
Undistributed earnings allocated to participating securities	(673)	(237)	0
Net income (loss) attributable to common stockholders—basic	$ 21,906	$ 7,538	$ (39,164)
Weighted average shares used in computing net income per share attributable to common stockholders - basic (in shares)	149,609	148,304	145,389
Net income (loss) per share attributable to common stockholders - basic (in dollars per share)	$ 0.15	$ 0.05	$ (0.27)
Diluted
Net income (loss) attributable to common stockholders—diluted	$ 21,906	$ 7,538	$ (39,164)
Weighted average shares used in computing net income per share attributable to common stockholders - basic (in shares)	149,609	148,304	145,389
Effect of dilutive securities (in shares)	175	329	0
Weighted average shares used in computing net income per share attributable to common stockholders - diluted (in shares)	149,784	148,633	145,389
Net income per share attributable to common stockholders - diluted (in dollars per share)	$ 0.15	$ 0.05	$ (0.27)