INDEBTEDNESS (Details Textual) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2015 USD ($) $ / shares shares	Dec. 31, 2014 USD ($) $ / shares shares
Long-term Debt, Gross	$ 143,750	$ 143,750
Long-term Debt, Percentage Bearing Fixed Interest, Percentage Rate	3.00%
Debt Instrument, Unamortized Discount	$ 27,016	33,059
Amortization of Financing Costs	$ 844	70
Convertible Senior Notes [Member]
Long-term Debt, Gross		143,800
Proceeds from Issuance of Debt		$ 122,600
Long-term Debt, Percentage Bearing Fixed Interest, Percentage Rate		3.00%
Underlying Shares Of Common Stock Convertible Debt | shares		2,068,792
Debt Instrument, Convertible, Conversion Price | $ / shares		$ 69.48
Debt Instrument, Convertible, Threshold Trading Days		20
Debt Instrument Percent Of Conversion Price		130.00%
Per Note Principal | $ / shares		$ 1,000
Debt Instrument, Unamortized Discount		$ 33,600
Deferred Offering Costs		$ 5,500
Exercise Price Of Bond Hedge | $ / shares		$ 69.48
Underlying Shares Of Common Stock Bond Hedge | shares	2,068,792	2,068,792
Class of Warrant or Right, Exercise Price of Warrants or Rights | $ / shares	$ 96.21	$ 96.21
Net Adjustments To Additional Paid In Capital Bond Hedge Acquired Warrant Issued Net		$ 15,600
Debt Instrument, Interest Rate, Effective Percentage	7.80%	7.70%
Debt Instrument, Convertible, Threshold Consecutive Trading Days		30 days
Amortization of Financing Costs		$ 4,200
Payments of Stock Issuance Costs		$ 1,300