Quarterly report pursuant to Section 13 or 15(d)

Debt Agreements (Details Textual)

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Debt Agreements (Details Textual) - USD ($)
$ / shares in Units, $ in Millions
1 Months Ended
Feb. 02, 2018
Mar. 21, 2018
Jul. 27, 2017
Mar. 31, 2018
Horizon Technology Finance Corporation [Member]        
Debt Instrument [Line Items]        
Class of Warrant or Right, Exercise Price of Warrants or Rights     $ 1.96  
Class of Warrant or Right, Number of Securities Called by Warrants or Rights     280,612  
Class of Warrant or Right, Terms     18 months  
Venture Loan [Member]        
Debt Instrument [Line Items]        
Early Repayment of Subordinated Debt $ 3.0      
Long-term Debt $ 7.0      
Venture Loan [Member] | Horizon Technology Finance Corporation [Member]        
Debt Instrument [Line Items]        
Debt Instrument, Face Amount     $ 7.0  
Molteni Loan [Member]        
Debt Instrument [Line Items]        
Long-term Debt   $ 4.0    
Conversion of Debt to Equity Description   In addition, Molteni has the right to convert its portion of the debt into shares of our common stock at a conversion price of $1.20 per share and is required to effect this conversion of debt to equity if we complete an equity financing resulting in gross proceeds of at least $10.0 million at a price per share of common stock in excess of $1.20 and repay the $1.6 million balance of Horizons loan amount.    
Proceeds from Subordinated Short-term Debt   $ 2.4    
Series A Warrants [Member]        
Debt Instrument [Line Items]        
Class of Warrant or Right, Exercise Price of Warrants or Rights       $ 4.85
Series A Warrants [Member] | Maximum [Member]        
Debt Instrument [Line Items]        
Class of Warrant or Right, Exercise Price of Warrants or Rights     $ 4.89  
Series A Warrants [Member] | Minimum [Member]        
Debt Instrument [Line Items]        
Class of Warrant or Right, Exercise Price of Warrants or Rights     $ 4.85  
New Horizon Warrants [Member]        
Debt Instrument [Line Items]        
Class of Warrant or Right, Exercise Price of Warrants or Rights   $ 1.20    
Class of Warrant or Right, Number of Securities Called by Warrants or Rights   40,000