Quarterly report pursuant to Section 13 or 15(d)

Note 4 - Stock-based Compensation (Details Textual)

v3.20.1
Note 4 - Stock-based Compensation (Details Textual) - USD ($)
1 Months Ended 3 Months Ended 6 Months Ended
Feb. 29, 2020
Mar. 31, 2020
Mar. 31, 2019
Mar. 31, 2020
Dec. 31, 2019
Mar. 31, 2019
Dec. 31, 2018
Share-based Payment Arrangement, Expense   $ 87,937 $ 563,666 $ 328,523   $ 1,102,190  
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount, Total   2,324,790   $ 2,324,790      
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition (Year)       4 years 146 days      
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross (in shares)       116,600   172,000  
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period (Year)       5 years 284 days   4 years  
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period (Year)       4 years 284 days   3 years  
Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price (in dollars per share)       $ 12.43   $ 12.17  
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term (Year)       2 years 113 days      
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value   $ 102,150   $ 102,150      
Proceeds from Stock Options Exercised       $ 2,582   $ 24  
Employee Stock Purchase Plan [Member]              
Share-based Compensation Arrangement by Share-based Payment Award, Market Price Percentage, Offering Date       85.00%      
Stock Issued During Period, Shares, Employee Stock Purchase Plans (in shares)         15,107   17,312
Share-based Compensation Arrangement by Share-based Payment Award, Purchase Price (in dollars per share)         $ 11.23   $ 8.43
Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized (in shares) 200,000            
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant (in shares)   234,739   234,739      
Minimum [Member]              
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period (Year)       3 years      
Maximum [Member]              
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period (Year)       5 years      
Share-based Payment Arrangement, Option [Member] | Minimum [Member]              
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period (Year)       3 years      
Share-based Payment Arrangement, Option [Member] | Maximum [Member]              
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period (Year)       5 years      
Restricted Stock [Member]              
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares)       19,455      
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)       $ 11.30      
Restricted Stock [Member] | Non-employee Directors [Member] | Stock Compensation Plan 2007 [Member]              
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period (Year)       1 year   1 year  
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares)       5,830   4,340  
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Intrinsic Value, Amount Per Share (in dollars per share)       $ 10.72      
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)           $ 14.40  
Restricted Stock [Member] | Minimum [Member] | Employees [Member] | Stock Compensation Plan 2007 [Member]              
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period (Year)       1 year      
Restricted Stock [Member] | Maximum [Member] | Employees [Member] | Stock Compensation Plan 2007 [Member]              
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period (Year)       10 years      
Performance Shares [Member] | Non-employee Directors [Member] | Stock Compensation Plan 2007 [Member]              
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period (Year)       1 year      
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares)       8,625      
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)       $ 11.86      
Selling, General and Administrative Expenses [Member]              
Share-based Payment Arrangement, Expense   $ 83,140 532,425 $ 318,928   $ 1,039,709  
Cost of Sales [Member]              
Share-based Payment Arrangement, Expense   $ 4,797 $ 31,241 $ 9,595   $ 62,481