NET (LOSS) INCOME PER COMMON SHARE (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Basic (loss) income per share
Net (loss) income	$ (21,653)	$ 12,746	$ (33,286)	$ 30,684
Denominator (in shares)	59,991,934	58,105,902	59,777,594	57,827,430
Basic net (loss) income per share (in dollars per share)	$ (0.36)	$ 0.22	$ (0.56)	$ 0.53
Numerator:
Net (loss) income	$ (21,653)	$ 12,746	$ (33,286)	$ 30,684
Denominator:
Denominator (in shares)	59,991,934	58,105,902	59,777,594	57,827,430
Add effect of dilutive securities:
Stock options and equivalents		2,324,000		2,431,000
Denominator for diluted net (loss) income per share (in shares)	59,991,934	60,430,456	59,777,594	60,258,445
Diluted net (loss) income per share (in dollars per share)	$ (0.36)	$ 0.21	$ (0.56)	$ 0.51
Total number of antidilutive shares excluded from the diluted net income (loss) per share	19,438,375	1,190	19,097,893	1,609
Convertible notes due 2021
Add effect of dilutive securities:
Total number of antidilutive shares excluded from the diluted net income (loss) per share	17,931,393		17,931,393
Stock options and equivalents
Add effect of dilutive securities:
Total number of antidilutive shares excluded from the diluted net income (loss) per share	1,506,982	1,190	1,166,500	1,609