(LOSS) PER SHARE PER SHARE (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2020	Jun. 30, 2019	Feb. 29, 2020
Earning per share reconciliation
Net (loss)	$ (20,740)	$ (25,372)	$ (32,296)	$ (28,717)	$ (46,112)	$ (61,013)
Weighted-average common shares outstanding (in shares)	80,224		78,987		80,016	78,787
(Loss) per share, basic (in dollars per share)	$ (0.26)		$ (0.41)		$ (0.58)	$ (0.77)
Weighted-average common shares outstanding, assuming dilution (in shares)	80,224		78,987		80,016	78,787
(Loss) per share, diluted (in dollars per share)	$ (0.26)		$ (0.41)		$ (0.58)	$ (0.77)
Outstanding anti-dilutive stock options and RSUs (in shares)	5,929		6,253		5,939	5,908
Convertible Debt
Earning per share reconciliation
Initial conversion price (in dollars per share)							$ 135.05