Note 12 - Subsequent Events (Details Textual) - $ / shares		3 Months Ended
	Jul. 21, 2021	Jun. 30, 2021	Jun. 30, 2020
Common Stock, Dividends, Per Share, Declared (in dollars per share)		$ 1.00	$ 1.00
Subsequent Event [Member]
Common Stock, Dividends, Per Share, Declared (in dollars per share)	$ 1.00
Dividends Payable, Date to be Paid	Aug. 31, 2021
Dividends Payable, Date of Record	Aug. 02, 2021