Annual report pursuant to Section 13 and 15(d)

DEBT - Schedule of Debt (Details)

v3.7.0.1
DEBT - Schedule of Debt (Details) - USD ($)
Mar. 31, 2017
Dec. 31, 2016
Mar. 31, 2016
Dec. 31, 2012
Long-term debt:        
Unamortized discount and debt issuance costs $ (3,472,000)   $ 0  
Long-term debt, net of unamortized discount and debt issuance costs $ 65,028,000   62,709,000  
4.50% convertible subordinated notes        
Debt Instrument [Line Items]        
Stated interest rate (as a percent) 4.50% 4.50%   4.50%
Long-term debt:        
Long-term debt       $ 70,000,000
Convertible subordinated debt        
Debt Instrument [Line Items]        
4.50% convertible subordinated notes $ 63,090,000   70,000,000  
Unamortized debt issuance costs (263,000)   (747,000)  
Convertible subordinated debt, net of unamortized debt issuance costs 62,827,000   69,253,000  
Credit agreement with Wells Fargo | Credit agreement with Wells Fargo        
Long-term debt, current:        
Credit agreement with Wells Fargo 0   3,000,000  
Long-term debt:        
Long-term debt 0   62,709,000  
Credit agreement with Wells Fargo | Revolving credit agreement        
Long-term debt:        
Long-term debt 46,400,000      
Credit agreement with Wells Fargo | Revolving credit agreement | Revolving credit agreement        
Long-term debt:        
Long-term debt 18,500,000   0  
Term loan agreement        
Long-term debt:        
Long-term debt $ 50,000,000   $ 0