Quarterly report pursuant to Section 13 or 15(d)

Note 5 - Stock-based Compensation (Details Textual)

v3.21.1
Note 5 - Stock-based Compensation (Details Textual) - USD ($)
3 Months Ended
Jun. 01, 2016
Mar. 31, 2021
Mar. 31, 2020
Dec. 31, 2020
Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross (in shares)   145,000 0    
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number, Ending Balance (in shares)   1,515,000 1,220,000 1,395,000 1,349,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period (in shares)   25,000 0    
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount, Total   $ 301,242      
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition (Month)   180 days      
Share-based Payment Arrangement, Expense   $ 27,711 $ 450    
The 2016 Stock Incentive Plan [Member]          
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized (in shares) 1,000,000        
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period (Year) 10 years        
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number, Ending Balance (in shares)   751,000      
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number (in shares)   371,000      
The 2006 Stock Incentive Plan [Member]          
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized (in shares)   1,950,000      
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period (Year)   10 years      
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number (in shares)   764,000      
Minimum [Member] | Share-based Payment Arrangement, Option [Member]          
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period (Month)   180 days      
Maximum [Member] | Share-based Payment Arrangement, Option [Member]          
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period (Month)   2 years