NET (LOSS) INCOME PER SHARE NET INCOME (LOSS) PER SHARE (Details) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2015	Jun. 30, 2014	Jun. 15, 2015
Antidilutive Securities Excluded from Computation of Net Loss Per Share [Line Items]
Convertible Notes Payable, Noncurrent	$ 125,000	$ 125,000		$ 125,000
Accounts Payable, Interest-bearing, Interest Rate				2.00%
Debt Instrument, Convertible, Terms of Conversion Feature	The Notes are convertible into cash, shares of the Company’s common stock or a combination of cash and shares of common stock, at the Company’s election, based on an initial conversion rate, subject to adjustment, of 45.5840 shares per $1,000 principal amount of Notes, which is equal to an initial conversion price of $21.94 per share.	The Notes are convertible into cash, shares of the Company’s common stock or a combination of cash and shares of common stock, at the Company’s election, based on an initial conversion rate, subject to adjustment, of 45.5840 shares per $1,000 principal amount of Notes, which is equal to an initial conversion price of $21.94 per share. Prior to December 15, 2019, the Notes are convertible only in the following circumstances: (1) during any calendar quarter commencing after September 30, 2015, if the last reported sale price of the Company’s common stock is greater than or equal to 130% of the applicable conversion price for at least 20 trading days during a period of 30 consecutive trading days ending on the last trading day of the preceding calendar quarter; (2) during the five business day period after any five consecutive trading day period (the “Measurement Period”) in which the trading price per $1,000 principal amount of notes for each trading day in the Measurement Period was less than 98% of the product of the last reported sale price of the Company’s common stock and the conversion rate on such trading day; or (3) upon the occurrence of specified corporate transactions.
Anti-dilutive potential common shares (in thousands of shares)		6,178	4,775
Debt Instrument, Call Feature		The Capped Call has a strike price of $21.94 and a cap price of $26.00 and is exercisable by the Company when and if the Notes are converted.
Options
Antidilutive Securities Excluded from Computation of Net Loss Per Share [Line Items]
Anti-dilutive potential common shares (in thousands of shares)		5,227	4,677
Non-vested restricted stock units
Antidilutive Securities Excluded from Computation of Net Loss Per Share [Line Items]
Anti-dilutive potential common shares (in thousands of shares)		951	98