Quarterly report pursuant to Section 13 or 15(d)

Note 6 - Note Payable (Details Textual)

v3.21.2
Note 6 - Note Payable (Details Textual) - USD ($)
3 Months Ended 6 Months Ended
Nov. 12, 2019
Dec. 29, 2017
May 22, 2017
Jun. 30, 2021
Jun. 30, 2020
Jun. 30, 2021
Jun. 30, 2020
Dec. 31, 2020
Notes Payable, Noncurrent, Total       $ 4,809,000   $ 4,809,000   $ 4,518,000 [1]
Series B Convertible Preferred Stock Into Common Stock [Member] | Minimum [Member]                
Conversion of Stock, Conversion Rate (in dollars per share) $ 15.30              
Series B Convertible Preferred Stock Into Common Stock [Member] | Maximum [Member]                
Conversion of Stock, Conversion Rate (in dollars per share) $ 18.36              
Warrants Issued Upon Conversion of Term Loan with CRG [Member]                
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares) 989,379              
Warrants and Rights Outstanding, Term (Year) 5 years              
Class of Warrants and Rights Outstanding, Exercise Price Percentage of Conversion Rate 120.00%              
Conversion of Term Loan with CRG Into Stock and Warrants [Member]                
Debt Conversion, Original Debt, Amount $ 28,981,000              
Debt Conversion, Converted Instrument, Amount $ 31,300,000              
Conversion of Term Loan with CRG Into Series B Convertible Preferred Stock [Member]                
Debt Conversion, Converted Instrument, Shares Issued (in shares) 31,300              
The 2017 Loan Agreement [Member]                
Notes Payable, Noncurrent, Total       4,809,000   4,809,000    
The 2017 Loan Agreement [Member] | CRG LP [Member]                
Debt Instrument, Face Amount     $ 20,000,000          
Debt Agreement, Covenant, Additional Funding     10,000,000          
Debt Agreement, Maximum Borrowing Capacity     $ 30,000,000          
Proceeds from Lines of Credit, Total   $ 10,000,000            
Debt Instrument, Back-end Facility Fee Percentage of Principal 25.00%   5.00%          
Paid-in-Kind Interest       148,000 $ 130,000 289,000 $ 256,000  
Notes Payable, Noncurrent, Total       $ 4,809,000   $ 4,809,000   $ 4,518,000
[1] The condensed consolidated balance sheet as of December 31, 2020 has been derived from the audited consolidated financial statements as of that date.