Quarterly report pursuant to Section 13 or 15(d)

Note 4 - Stock-based Compensation (Details Textual)

v3.19.1
Note 4 - Stock-based Compensation (Details Textual) - USD ($)
3 Months Ended 6 Months Ended
Mar. 31, 2019
Dec. 31, 2018
Mar. 31, 2018
Dec. 31, 2017
Mar. 31, 2019
Mar. 31, 2018
Share-based Payment Arrangement, Expense $ 563,666   $ 485,794   $ 1,102,190 $ 969,081
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount, Total 2,965,292       $ 2,965,292  
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition         5 years 146 days  
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross         172,000 0
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period         4 years  
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period         3 years  
Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price         $ 12.17  
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value         $ 3.53  
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term         1 year 146 days  
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value 287,850       $ 287,850  
Proceeds from Stock Options Exercised         $ 24 $ 17,949
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period         6,750 6,100
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   17,312   14,242    
Share-based Compensation Arrangement by Share-based Payment Award, Purchase Price   $ 8.43   $ 10.41    
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant   69,769        
Share-based Payment Arrangement, Option [Member] | Director [Member]            
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period         6 years  
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period         1 year  
Share-based Payment Arrangement, Option [Member] | Minimum [Member]            
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period         3 years  
Share-based Payment Arrangement, Option [Member] | Maximum [Member]            
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period         5 years  
Restricted Stock [Member]            
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period         4,340  
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value         $ 14.40  
Restricted Stock [Member] | Non Employee Directors [Member] | Stock Compensation Plan 2007 [Member]            
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period         1 year 1 year
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period         4,340 4,235
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value         $ 14.40 $ 14.75
Restricted Stock [Member] | Minimum [Member] | Employees [Member] | Stock Compensation Plan 2007 [Member]            
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period         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         10 years  
Selling, General and Administrative Expenses [Member]            
Share-based Payment Arrangement, Expense 532,425   443,763   $ 1,039,709 $ 885,020
Cost of Sales [Member]            
Share-based Payment Arrangement, Expense $ 31,241   $ 42,031   $ 62,481 $ 84,061