Note 10 - Stock-based Compensation (Details Textual) - USD ($)						1 Months Ended				3 Months Ended		9 Months Ended
		Jan. 09, 2020	Jan. 06, 2020	Nov. 30, 2018	Nov. 14, 2017	Nov. 30, 2019	Dec. 31, 2018	Nov. 30, 2018	Nov. 30, 2017	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019	Nov. 14, 2019	Jun. 30, 2019
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number, Ending Balance (in shares)										100,000		100,000
Share-based Payment Arrangement, Expense										$ 862,125	$ 724,970	$ 2,485,448	$ 2,255,937
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross (in shares)	[1]											100,000
Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price (in dollars per share)	[1]											$ 14.50
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period (in shares)											0
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term (Year)												4 years 292 days
Share-based Payment Arrangement, Nonvested Award, Option, Cost Not yet Recognized, Amount										$ 655,839		$ 655,839
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate												1.56%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term (Year)												3 years 109 days
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate												74.00%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate												0.00%
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value (in dollars per share)												$ 7.42
President and CEO [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross (in shares)			100,000
Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price (in dollars per share)			$ 14.50
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number, Ending Balance (in shares)										534,666		534,666
Restricted Stock [Member] | President and CEO [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares)		75,000
The 2010 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized (in shares)					500,000
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized (in shares)														2,000,000
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount, Total										$ 4,064,923		$ 4,064,923
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period (in shares)										0		0	35,625
Share-based Compensation Arrangement by Share-based Payment Award, Shares Issued in Period (in shares)													19,513
Proceeds from Stock Options Exercised													$ 0
The 2010 Plan [Member] | Restricted Stock [Member] | Executives and Non-executive Directors [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares)				155,000				155,000	155,000
The 2010 Plan [Member] | Restricted Stock [Member] | Executives and Non-executive Directors [Member] | November 2018 Grant [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number, Ending Balance (in shares)										155,000		155,000
The 2010 Plan [Member] | Restricted Stock [Member] | Two Executives and Non-executive Directors [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares)							146,666
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period (in shares)							117,332
The 2010 Plan [Member] | Restricted Stock [Member] | Two Executives and Non-executive Directors [Member] | December 2018 Grant [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number, Ending Balance (in shares)										146,666		146,666
The 2010 Plan [Member] | Restricted Stock [Member] | Two Executives and Non-executive Directors [Member] | November 2019 Grant [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number, Ending Balance (in shares)										158,000		158,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares)						158,000

[1] The fair value of each option is estimated as of the date of grant using the Black-Scholes option-pricing model with the following weighted-average assumptions: (i) risk-free interest rate of 1.56%; (ii) expected life of 3.3 years; (iii) expected volatility of 74%; and (iv) expected dividend yield of 0%. The weighted average fair value per share for the options granted is $7.42