NET INCOME (LOSS) PER SHARE (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Numerator for basic and diluted loss per share
Net loss	$ (5,037)	$ (14,031)	$ (16,514)	$ (37,169)
Denominator
Weighted average shares of common stock outstanding (in shares)	35,463	33,083	34,587	32,896
Net loss per share
Basic net loss per share of common stock (in dollars per share)	$ (0.14)	$ (0.42)	$ (0.48)	$ (1.13)