Annual report pursuant to Section 13 and 15(d)

Note 11 - Share-based Compensation - Summary of Stock Option and Inducement Stock Option Activity (Details)

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Note 11 - Share-based Compensation - Summary of Stock Option and Inducement Stock Option Activity (Details) - USD ($)
 12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Inducement Stock Options [Member]      
Outstanding, number of authorized shares (in shares) [1] 125,000  
Outstanding, weighted average exercise price (in dollars per share) $ 2.55  
Outstanding, weighted average remaining contractual term (Year) 4 years 153 days 5 years 153 days
Outstanding, aggregate intrinsic value $ 747,500 $ 111,250
Granted, number of authorized shares (in shares) [1] 125,000  
Granted, weighted average exercise price (in dollars per share) $ 2.55  
Granted, weighted average remaining contractual term (Year) 5 years 153 days  
Exercised, number of authorized shares (in shares) [1]  
Forfeited, number of authorized shares (in shares) [1]  
Exercisable, number of authorized shares (in shares) [1] 49,479    
Exercisable, weighted average exercise price (in dollars per share) $ 2.55    
Outstanding, number of authorized shares (in shares) [1] 125,000 125,000
Outstanding, weighted average exercise price (in dollars per share) $ 2.55 $ 2.55
Granted, aggregate intrinsic value $ 111,250  
2014 Amended and Restated Stock Incentive Plan [Member]      
Outstanding, number of authorized shares (in shares) 2,224,167 1,962,500  
Outstanding, weighted average exercise price (in dollars per share) $ 2.67 $ 2.44  
Outstanding, weighted average remaining contractual term (Year) 1 year 295 days 3 years 3 days 3 years 65 days
Outstanding, aggregate intrinsic value $ 12,989,767 $ 1,719,584
Granted, number of authorized shares (in shares) 670,000 825,000  
Granted, weighted average exercise price (in dollars per share) $ 3.77 $ 3.14  
Granted, weighted average remaining contractual term (Year) 4 years 146 days 3 years 233 days  
Exercised, number of authorized shares (in shares) (213,056) (10,953)  
Exercised, weighted average exercise price (in dollars per share) $ 2.33 $ 2.15  
Exercised, aggregate intrinsic value $ 624,462 $ 12,159  
Exercised shares forgone to satisfy minimum statutory withholding, number of authorized shares (in shares) (51,339) (5,134)  
Exercised shares forgone to satisfy minimum statutory withholding, weighted average exercise price (in dollars per share) $ 2.33 $ 2.15  
Cashless exercise, number of authorized shares (in shares) (184,493) (33,079)  
Cashless exercise, weighted average exercise price (in dollars per share) $ 2.33 $ 2.15  
Forfeited, number of authorized shares (in shares) (101,946) (514,167)  
Forfeited, weighted average exercise price (in dollars per share) $ 3.63 $ 2.62  
Exercisable, number of authorized shares (in shares)   1,101,910  
Exercisable, weighted average exercise price (in dollars per share)   $ 2.52  
Outstanding, number of authorized shares (in shares) 2,343,333 2,224,167 1,962,500
Outstanding, weighted average exercise price (in dollars per share) $ 2.99 $ 2.67 $ 2.44
2014 Amended and Restated Stock Incentive Plan [Member] | 2007 Plan (Options) [Member]      
Exercisable, number of authorized shares (in shares) 1,501,750    
Exercisable, weighted average exercise price (in dollars per share) $ 2.69    
[1] Represents inducement stock options to purchase shares of the Company's Common Stock to executive level managers.