Note 12 - Subsequent Events (Details Textual) - $ / shares		3 Months Ended		6 Months Ended
	Oct. 21, 2020	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Common Stock, Dividends, Per Share, Declared (in dollars per share)		$ 1	$ 1	$ 2	$ 2
Subsequent Event [Member]
Common Stock, Dividends, Per Share, Declared (in dollars per share)	$ 1
Subsequent Event [Member] | Common Stock [Member]
Dividends Payable, Date to be Paid	Nov. 30, 2000
Dividends Payable, Date of Record	Nov. 02, 2020