LONG TERM DEBT AND CREDIT AGREEMENT (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Jun. 15, 2015	Dec. 31, 2014
Line of Credit Facility, Fair Value of Amount Outstanding	$ 10,000		$ 10,000
Principal Amount	125,000		125,000		$ 125,000
Unamortized debt discount	(28,298)		(28,298)
Debt issuance costs	(3,641)		(3,641)		4,700
Convertible Notes Payable Accumulated Accretion	1,544		1,544
Net Carrying Value	$ 94,605		$ 94,605		$ 96,700
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.		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.
Adjustments to Additional Paid in Capital, Equity Component of Convertible Debt, Subsequent Adjustments			$ 28,300
Debt Instrument, Interest Rate, Effective Percentage					7.66%
Interest Expense	$ 2,473	$ 458	3,765	$ 1,246
Increase (Decrease) in Deferred Income Taxes			$ 6,504	$ 6
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.
Net Proceeds from Issuance of Convertible Notes Payable					$ 120,300
Line of Credit Facility, Interest Rate Description			Interest accrues on outstanding borrowings under the Credit Facility at a rate of a Eurodollar Rate (as defined in the Credit Facility) plus 2.00% or a Base Rate (as defined in the Credit Facility) plus 1.00%, at the option of the Company. The Company must also pay to the Lenders, on a quarterly basis, an unused line fee at a rate of 0.25% per annum. During the term of the Credit Facility, the Company is entitled to reduce the maximum amounts of the Lenders’ commitments, subject to the payment of certain fees based on the amount of any reduction.
Short-term Debt, Fair Value	10,000		$ 10,000			$ 0
Debt [Member]
Debt issuance costs					3,600
Equity [Member]
Debt issuance costs					$ 1,100
Convertible Debt [Member]
Interest Expense	$ 1,500