Quarterly report pursuant to Section 13 or 15(d)

Note 4 - Stock-based Compensation (Details Textual)

v3.10.0.1
Note 4 - Stock-based Compensation (Details Textual) - USD ($)
3 Months Ended 6 Months Ended 9 Months Ended
Jun. 30, 2018
Dec. 31, 2017
Jun. 30, 2017
Jun. 30, 2018
Jun. 30, 2018
Jun. 30, 2017
Allocated Share-based Compensation Expense, Total $ 519,223   $ 590,419   $ 1,488,304 $ 1,774,330
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Total 3,894,131     $ 3,894,131 $ 3,894,131  
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition         6 years 109 days  
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross         72,000 0
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period         5 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         $ 13.35  
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value         $ 5.15  
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term         3 years 361 days  
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value 102,052     102,052 $ 102,052  
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term         2 years 51 days  
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value $ 267,652     $ 267,652 $ 267,652  
Proceeds from Stock Options Exercised         $ 21,174 $ 28,718
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period         7,350 15,850
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   14,242   15,932    
Share-based Compensation Arrangement by Share-based Payment Award, Purchase Price   $ 10.41   $ 9.39    
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant 87,081     87,081 87,081  
Restricted Stock [Member]            
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period         7,235  
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value         $ 14.17  
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         3,795 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         $ 16.45 $ 16.45
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  
Minimum [Member] | Restricted Stock [Member] | Employee and Non-Employee Directors [Member] | Stock Compensation Plan 2007 [Member]            
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period         1 year  
Maximum [Member] | Restricted Stock [Member] | Employee and Non-Employee Directors [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]            
Allocated Share-based Compensation Expense, Total $ 477,193   535,719   $ 1,362,213 $ 1,610,229
Cost of Sales [Member]            
Allocated Share-based Compensation Expense, Total $ 42,030   $ 54,700   $ 126,091 $ 164,101