NET LOSS PER SHARE - Schedule of Computation of Basic and Diluted Net Loss Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Numerator:
Net loss	$ (16,723)	$ (603)	$ (35,518)	$ (6,923)
Denominator:
Shares used in computing net loss per share, basic and diluted	46,620	44,319	46,415	44,136
Net loss per share, basic and diluted (in usd per share)	$ (0.36)	$ (0.01)	$ (0.77)	$ (0.16)