DEBT (Details)
3 Months Ended 9 Months Ended
Aug. 11, 2016
USD ($)
Sep. 30, 2016
USD ($)
$ / shares
Sep. 30, 2015
USD ($)
Sep. 30, 2016
USD ($)
trading_day
$ / shares
Sep. 30, 2015
USD ($)
Aug. 31, 2016
USD ($)
Debt Instrument [Line Items]            
Proceeds from issuance of convertible senior notes, net of issuance costs       $ 47,575,000 $ 0  
Deferred convertible senior notes issuance costs       486,000 0  
Repayments of Lines of Credit       19,500,000 25,000,000  
Interest Expense   $ 1,319,000 $ 110,000 2,705,000 $ 354,000  
Letter of credit   $ 6,000,000   6,000,000    
Convertible Senior Notes Due 2036            
Debt Instrument [Line Items]            
Principal amounts of debt $ 50,000,000         $ 50,000,000
Interest rate (as a percent) 4.125%          
Proceeds from issuance of convertible senior notes, net of issuance costs       47,091,000    
Deferred convertible senior notes issuance costs       $ 2,909,000    
Convertible debt, threshold trading days | trading_day       20    
Convertible debt, threshold consecutive trading days       30 days    
Convertible debt, threshold percentage of stock price trigger       130.00%    
Convertible debt, measurement period (in trading days)       5 days    
Convertible debt, maximum percentage of trading price per $1,000 principal amount trigger       98.00%    
Convertible debt, conversion ratio       0.0457603    
Convertible debt, conversion price (in usd per share) | $ / shares   $ 21.85   $ 21.85    
Fair value of long term debt $ 38,334,000 $ 36,352,000   $ 36,352,000    
Fair value of embedded conversion option $ 11,666,000          
Interest expense   558,000   558,000    
Interest expense to be paid in cash   281,000   281,000    
Interest expense, non cash accretion of debt discount   277,000   277,000    
Long-term debt   $ 38,648,000   $ 38,648,000    
Revolving Credit Facility            
Debt Instrument [Line Items]            
Long-term debt, average interest rate (as a percent)   4.25%   4.25%    
Unused borrowing capacity   $ 46,558,000   $ 46,558,000    
Revolving Credit Facility | October 2015 Amendment            
Debt Instrument [Line Items]            
Line of Credit Facility, Maximum Borrowing Capacity   55,000,000   55,000,000    
Revolving Credit Facility | Credit Agreement 2012            
Debt Instrument [Line Items]            
Interest Expense   143,000   263,000    
Revolving Credit Facility | Line of Credit | Amended Credit Agreement 2012            
Debt Instrument [Line Items]            
Maximum amount of distributions for interest payments           4,000,000
Maximum amount of distributions for cash payments           $ 1,500,000
Revolving Credit Facility | Line of Credit | Credit Agreement 2012            
Debt Instrument [Line Items]            
Amortization of Financing Costs   51,000   143,000    
Letter of Credit | Line of Credit | Amended Credit Agreement 2012            
Debt Instrument [Line Items]            
Line of Credit Facility, Maximum Borrowing Capacity   10,000,000   10,000,000    
Revolving Credit Facility, Swing Line Loan | Line of Credit | Amended Credit Agreement 2012            
Debt Instrument [Line Items]            
Line of Credit Facility, Maximum Borrowing Capacity   $ 5,000,000   5,000,000    
Accounting Standards Update 2015-03 | Long-term Debt | Convertible Senior Notes Due 2036            
Debt Instrument [Line Items]            
Deferred convertible senior notes issuance costs       (2,228,000)    
Accounting Standards Update 2015-03 | Additional Paid-in Capital | Convertible Senior Notes Due 2036            
Debt Instrument [Line Items]            
Deferred convertible senior notes issuance costs       $ (681,000)