Quarterly report pursuant to Section 13 or 15(d)

Note 4 - Stock-based Compensation (Details Textual)

v3.19.2
Note 4 - Stock-based Compensation (Details Textual) - USD ($)
3 Months Ended 6 Months Ended 9 Months Ended
Jun. 30, 2019
Jun. 30, 2018
Jun. 30, 2019
Dec. 31, 2018
Jun. 30, 2019
Jun. 30, 2018
Share-based Payment Arrangement, Expense $ 433,438 $ 519,223     $ 1,535,628 $ 1,488,304
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount, Total 2,553,214   $ 2,553,214   $ 2,553,214  
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition         5 years 73 days  
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross         172,000 72,000
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period         4 years 5 years
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period         3 years 3 years
Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price         $ 12.17 $ 13.35
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 51 days  
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value $ 253,413   $ 253,413   $ 253,413  
Proceeds from Stock Options Exercised         $ 24 $ 21,174
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     19,923 17,312    
Share-based Compensation Arrangement by Share-based Payment Award, Purchase Price     $ 8.43 $ 8.43    
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant 49,846   49,846   49,846  
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] | Employees [Member] | Stock Compensation Plan 2007 [Member]            
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period           1 year
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period           3,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value           $ 13.35
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 3,795
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 $ 16.45
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 $ 410,784 477,193     $ 1,450,493 $ 1,362,213
Cost of Sales [Member]            
Share-based Payment Arrangement, Expense $ 22,654 $ 42,030     $ 85,139 $ 126,091