Note 11 - Subsequent Events (Details Textual) - $ / shares		3 Months Ended		6 Months Ended
	Oct. 18, 2017	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Common Stock, Dividends, Per Share, Declared		$ 1	$ 1	$ 2	$ 2
Subsequent Event [Member]
Common Stock, Dividends, Per Share, Declared	$ 1