Note 4 - Stock Based Compensation (Details Textual) - USD ($) | 3 Months Ended |
Dec. 31, 2016 | Dec. 31, 2015 |
Allocated Share-based Compensation Expense | $ 593,746 | $ 226,767 |
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized | $ 6,860,649 | |
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition | 7 years 292 days | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross | 0 | 0 |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term | 3 years 73 days | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value | $ 788,892 | |
Proceeds from Stock Options Exercised | $ 17 | $ 34,990 |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period | 10,000 | 8,000 |
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 | 11,144 | 10,352 |
Share-based Compensation Arrangement by Share-based Payment Award, Purchase Price | $ 15.21 | $ 11.40 |
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant | 131,978 | |
Restricted Stock [Member] | | |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period | | |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value | | |
Restricted Stock [Member] | Stock Compensation Plan 2007 [Member] | | |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period | 0 | |
Restricted Stock [Member] | Employees [Member] | Stock Compensation Plan 2007 [Member] | | |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period | | 5 years |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period | | 8,500 |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value | | $ 13.64 |
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 | $ 539,046 | $ 204,881 |
Cost of Sales [Member] | | |
Allocated Share-based Compensation Expense | $ 54,700 | $ 21,886 |