NET (LOSS) INCOME PER SHARE (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Basic and diluted net (loss) income per share
Net (loss) income	$ (21,048)	$ (26,659)	$ 12,776	$ (53,400)
Denominator (in shares)	63,718,562	62,531,696	63,611,160	62,331,471
Basic net (loss) income per share (in dollars per share)	$ (0.33)	$ (0.43)	$ 0.20	$ (0.86)
Diluted net (loss) income per share
Net (loss) income	$ (21,048)	$ (26,659)	$ 12,776	$ (53,400)
Denominator for basic (loss) income per share (in shares)	63,718,562	62,531,696	63,611,160	62,331,471
Denominator for diluted (loss) income per share: (in shares)	63,718,562	62,531,696	64,107,109	62,331,471
Diluted net (loss) income per share (in dollars per share)	$ (0.33)	$ (0.43)	$ 0.20	$ (0.86)
Potentially dilutive common shares:
Total potentially dilutive common shares (in shares)			21,833,000	26,146,000
Convertible debt
Potentially dilutive common shares:
Total potentially dilutive common shares (in shares)			17,931,000	17,931,000
Stock options and equivalents
Diluted net (loss) income per share
Add effect of diluted securities			496,000
Potentially dilutive common shares:
Total potentially dilutive common shares (in shares)			3,902,000	8,215,000