Annual report pursuant to Section 13 and 15(d)

Note 13 - Summary of Stock Options (Details Textual)

v3.20.4
Note 13 - Summary of Stock Options (Details Textual) - USD ($)
1 Months Ended 12 Months Ended
Aug. 22, 2016
Jun. 30, 2020
Jan. 31, 2020
Sep. 30, 2019
Jul. 31, 2019
Jun. 30, 2019
Apr. 30, 2019
Jan. 31, 2019
Aug. 31, 2017
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Jan. 01, 2020
Nov. 26, 2019
Jan. 01, 2019
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number, Ending Balance (in shares)                   986,399 1,008,833 4,098      
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price, Ending Balance (in dollars per share)                   $ 19.10 $ 22.47 $ 4,567.36      
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term (Year)                   8 years 328 days 9 years 328 days 7 years 146 days      
Proceeds from Stock Plans                   $ 56,000        
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross (in shares)                   146,700 1,006,602        
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period (in shares)                          
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate                          
Consultant [Member]                              
Stock Issued During Period, Shares, Restricted Stock Award, Gross (in shares)   25       25                  
Director [Member]                              
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares)         38   53                
Stock Issued During Period, Shares, Restricted Stock Award, Gross (in shares)         38   53                
Restricted Stock [Member] | Director [Member]                              
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value (in dollars per share)         $ 380.80   $ 910                
Share-based Payment Arrangement, Option [Member]                              
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate                   0.00%          
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount, Total                   $ 4,781,000          
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition (Year)                   2 years 182 days          
The 2006 Stock Option Plan [Member]                              
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number, Ending Balance (in shares)                   12          
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant (in shares)                   0          
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price, Ending Balance (in dollars per share)                   $ 9,920          
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term (Year)                   2 years 36 days          
The 2013 Plan [Member]                              
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number, Ending Balance (in shares)                   986,387          
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant (in shares)                   466,200          
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price, Ending Balance (in dollars per share)                   $ 18.98          
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term (Year)                   8 years 328 days          
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period (Year)                   10 years          
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period (Year)                   4 years          
Share-based Compensation Arrangement by Share-based Payment Award, Percentage of Outstanding Stock Maximum                   10.00%          
Share-based Compensation Arrangement by Share-based Payment Award, Purchase Price of Common Stock, Percent                   110.00%          
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized, Percentage Increase of Outstanding Common Stock 4.00%                            
Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized (in shares)     263,993         2,044              
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized (in shares)                   1,451,246   4,914 1,451,246 1,187,253 6,958
Common Stock Shares Reserved For Future Issuance Percentage       18.00%                      
The 2013 Plan [Member] | Employees and Nonemployees [Member]                              
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross (in shares)                   146,700 1,006,602        
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value (in dollars per share)                   $ 4.08 $ 7.23        
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period (in shares)                   0 0        
The 2013 Plan [Member] | Restricted Stock [Member]                              
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number, Ending Balance (in shares)                   234          
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares)               384   0          
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period (in shares)                   18 132        
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period (in shares)                   0          
The 2013 Plan [Member] | Underwritten Public Offering [Member]                              
Minimum Gross Proceeds From Equity Offering Amount Used In Calculation Of Reserved Shares Percentage       $ 5,000,000                      
The 2013 Plan [Member] | Holdings Greater Than 10 Percent of Shares Outstanding [Member]                              
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period (Year)                   5 years          
2017 Employee Stock Purchase Plan [Member]                              
Share-based Compensation Arrangement by Share-based Payment Award, Purchase Price of Common Stock, Percent                 85.00%            
Share-based Compensation Arrangement by Share-based Payment Award, Maximum Number of Shares Per Employee (in shares)                 200            
Stock Issued During Period, Shares, Employee Stock Purchase Plans (in shares)                   84 154        
Proceeds from Stock Plans                   $ 1,000 $ 56,000        
Employee Stock Ownership Plan (ESOP), Number of Suspense Shares (in shares)                   22