Note 9 - Cash Dividends (Details Textual) - USD ($)		9 Months Ended
	May 11, 2021	Mar. 31, 2021	Mar. 31, 2020
Payments of Dividends, Total		$ 4,000,000.0	$ 4,000,000.0
Dividends Accrued		$ 109,685	$ 59,077
Subsequent Event [Member]
Quarterly Indicated Per Share Dividend Rate (in dollars per share)	$ 0.05
Annual Indicated per Share Dividend Rate (in dollars per share)	$ 0.20
Dividends Payable, Date to be Paid	May 11, 2021
Dividends Payable, Date of Record	May 03, 2021