NET INCOME (LOSS) PER SHARE - Tabular Disclosure (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Basic
Net income (loss)	$ 7,775	$ (39,164)	$ 34,818
Undistributed earnings allocated to participating securities	(237)	0	(990)
Net income (loss) attributable to common stockholders—basic	$ 7,538	$ (39,164)	$ 33,828
Weighted average shares used in computing net income per share attributable to common stockholders - basic (in shares)	148,304	145,389	142,225
Net income (loss) per share attributable to common stockholders - basic (in dollars per share)	$ 0.05	$ (0.27)	$ 0.24
Diluted
Net income (loss) attributable to common stockholders—diluted	$ 7,538	$ (39,164)	$ 33,828
Weighted average shares used in computing net income per share attributable to common stockholders - basic (in shares)	148,304	145,389	142,225
Effect of dilutive securities (in shares)	329	0	512
Weighted average shares used in computing net income per share attributable to common stockholders - diluted (in shares)	148,633	145,389	142,737
Net income per share attributable to common stockholders - diluted (in dollars per share)	$ 0.05	$ (0.27)	$ 0.24