v3.8.0.1
Note 7 - Long-term Debt (Details Textual)
$ / shares in Units, $ in Thousands
1 Months Ended 6 Months Ended 12 Months Ended
Mar. 02, 2017
USD ($)
Sep. 18, 2015
$ / shares
shares
Dec. 16, 2013
USD ($)
$ / shares
shares
Sep. 30, 2016
$ / shares
shares
Dec. 31, 2013
$ / shares
shares
Jun. 30, 2016
$ / shares
Mar. 01, 2020
Mar. 01, 2019
Mar. 01, 2018
Dec. 31, 2017
USD ($)
Dec. 31, 2016
USD ($)
Dec. 31, 2015
USD ($)
shares
Oct. 01, 2017
USD ($)
Sep. 17, 2015
$ / shares
Dec. 31, 2014
USD ($)
Sep. 24, 2014
USD ($)
Jun. 16, 2014
USD ($)
Repayments of Long-term Debt                   $ 3,514 $ 4,534          
Common Stock Warrants Exercised | shares                       847,058          
Fair Value of Contingent Put Option, Liability                   207 124            
Interest Expense                   3,316 $ 2,770 $ 2,977          
Hercules Warrants [Member]                                  
Common Stock Warrants Exercised | shares   176,730 176,730 176,730 176,730                        
Class of Warrant or Right, Exercise Price of Warrants or Rights | $ / shares   $ 3.88 $ 6.79 $ 3.07 $ 9.67                 $ 6.79      
Investment Warrants, Exercise Price | $ / shares       $ 3.07 $ 6.79 $ 3.88                      
Amended and Restated Loan and Security Agreement [Member]                                  
Line of Credit Facility, Maximum Borrowing Capacity     $ 40,000                            
Number of Tranches for Loan and Security Agreement     3                            
Debt Instrument, Fair Value Disclosure                             $ 24,900    
Long-term Debt Maturities Balloon Payments                         $ 1,700        
Debt Instrument, Variable Rate Threshold 9.55%                                
Debt Instrument, Percentage Used to Calculate Variable Rate 3.50%                                
Debt Instrument, Final Payment, Percentage of Aggregate Principal Amount 6.50%                                
Amended and Restated Loan and Security Agreement [Member] | Prime Rate [Member]                                  
Debt Instrument, Interest Rate, Effective Percentage                     9.55%            
Amended and Restated Loan and Security Agreement [Member] | First Tranche [Member]                                  
Debt Instrument, Face Amount $ 20,500   $ 15,000                            
Repayments of Long-term Debt     8,600                            
Amended and Restated Loan and Security Agreement [Member] | Second Tranche [Member]                                  
Debt Instrument, Face Amount                                 $ 10,000
Amended and Restated Loan and Security Agreement [Member] | Third Tranche [Member]                                  
Line of Credit Facility, Maximum Borrowing Capacity                               $ 15,000  
Hercules Loan and Security Agreement [Member]                                  
Additional Default Interest Rate 5.00%                                
Fair Value of Contingent Put Option, Liability     $ 32             200 $ 100            
Long-term Line of Credit                   19,100 21,500            
Interest Expense                   $ 3,300 $ 2,800 $ 3,000          
Hercules Loan and Security Agreement [Member] | Scenario, Forecast [Member]                                  
Prepayment Charge of Term Loan Percentage             1.00% 2.00% 3.00%