Quarterly report pursuant to Section 13 or 15(d)

DEBT - Schedule of Debt (Details)

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DEBT - Schedule of Debt (Details) - USD ($)
Sep. 30, 2017
Mar. 31, 2017
Dec. 31, 2012
Debt Instrument [Line Items]      
Unamortized discount and debt issuance costs $ (2,894,000) $ (3,472,000)  
Long-term debt 130,615,000    
Long-term debt, net of unamortized discount and debt issuance costs 70,631,000 65,028,000  
4.50% convertible subordinated notes      
Debt Instrument [Line Items]      
Long-term debt $ 57,090,000   $ 70,000,000
Stated interest rate 4.50%   4.50%
Revolving credit agreement      
Debt Instrument [Line Items]      
Long-term debt $ 23,525,000    
Convertible subordinated debt      
Debt Instrument [Line Items]      
Unamortized discount and debt issuance costs (56,000) (263,000)  
Convertible subordinated debt, net of unamortized debt issuance costs 57,034,000 62,827,000  
Convertible subordinated debt | 4.50% convertible subordinated notes      
Debt Instrument [Line Items]      
4.50% convertible subordinated notes $ 57,090,000 63,090,000  
Stated interest rate 4.50%    
Revolving credit agreement | Revolving credit agreement | Revolving credit agreement      
Debt Instrument [Line Items]      
Long-term debt $ 23,525,000 18,500,000  
Term loan agreement      
Debt Instrument [Line Items]      
Long-term debt $ 50,000,000 $ 50,000,000