Quarterly report pursuant to Section 13 or 15(d)

Note 6 - Stock-based Compensation (Details Textual)

v3.21.2
Note 6 - Stock-based Compensation (Details Textual) - USD ($)
 3 Months Ended 9 Months Ended
Jun. 01, 2016
Sep. 30, 2021
Jun. 30, 2021
Mar. 31, 2021
Sep. 30, 2020
Jun. 30, 2020
Mar. 31, 2020
Sep. 30, 2021
Sep. 30, 2020
Dec. 31, 2020
Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number, Ending Balance (in shares)   1,227,500 1,262,500 1,515,000 1,430,000 1,220,000 1,220,000 1,227,500 1,430,000 1,395,000 1,349,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross (in shares)   30,000 127,500 145,000 210,000 10,000 0 302,500 220,000    
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period (in shares)   65,000 360,000 25,000 0     450,000 0    
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount, Total   $ 163,847           $ 163,847      
Share-based Payment Arrangement, Expense   $ 80,882     $ 6,365     $ 220,455 $ 7,171    
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)   853,500           853,500      
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number (in shares)   556,000           556,000      
The 2006 Stock Incentive Plan [Member]                      
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized (in shares)   1,950,000           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, Outstanding, Number, Ending Balance (in shares)   374,000           374,000      
Minimum [Member] | Share-based Payment Arrangement, Option [Member]                      
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period (Month)               6 months      
Maximum [Member] | Share-based Payment Arrangement, Option [Member]                      
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period (Month)               2 years