EARNINGS PER SHARE (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2013		Jun. 30, 2012		Jun. 30, 2013		Jun. 30, 2012
Basic earnings per share:
Net income (loss)	$ 13,672		$ (7,176)		$ 24,575		$ 285
Weighted-average common shares	29,178,000		28,619,000		28,967,000		28,423,000
Basic earnings (loss) per share	$ 0.47		$ (0.25)		$ 0.85		$ 0.01
Diluted earnings per share:
Net income (loss)	$ 13,672		$ (7,176)		$ 24,575		$ 285
Weighted-average common shares	29,178,000		28,619,000		28,967,000		28,423,000
Effect of dilutive securities:
Employee stock plans	980,000	[1]	0	[1]	1,010,000	[1]	1,201,000	[1]
Diluted weighted-average common shares	30,158,000	[1]	28,619,000	[1]	29,977,000	[1]	29,624,000	[1]
Diluted earnings (loss) per share	$ 0.45	[1]	$ (0.25)	[1]	$ 0.82	[1]	$ 0.01	[1]
Antidilutive shares attributable to stock-based awards outstanding excluded from computation of diluted earnings per share	167,862				166,042		306,586

[1] The Company includes the shares underlying performance-based awards in the calculation of diluted earnings per share if the performance conditions have been satisfied as of the end of the reporting period and excludes such shares when the necessary conditions have not been met. The Company has excluded the shares underlying the 2013 and 2012 awards in the 2013 and 2012 calculation, respectively, as those shares were not contingently issuable as of the end of the period.