NET INCOME (LOSS) PER COMMON SHARE (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
NET INCOME (LOSS) PER COMMON SHARE
Net income (loss)	$ 12,746	$ 478	$ 30,684	$ (5,002)
Denominator for basic net income (loss) per share (in shares)	58,105,902	56,562,433	57,827,430	56,511,911
Net effect of potential dilutive common shares (in shares)	2,324,000	580,000	2,431,000
Denominator for diluted net income (loss) per share: (in shares)	60,430,456	57,142,343	60,258,445	56,511,911
Basic net income (loss) per share (in dollars per share)	$ 0.22	$ 0.01	$ 0.53	$ (0.09)
Diluted net income (loss) per share (in dollars per share)	$ 0.21	$ 0.01	$ 0.51	$ (0.09)
Total number of anti-dilutive outstanding common stock options excluded from the diluted net income per common share computation (in shares)	1,600,000	5,900,000	1,200,000	7,300,000