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Note 6 - Shareholder's Equity - Declared Dividends (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Mar. 31, 2021	May 04, 2020	Jul. 23, 2018
Per Share Dividend (in dollars per share)	$ 0.28	$ 0.28	$ 0.27
Dividend Declared May 4, 2020 [Member]
Declaration Date	May 04, 2020
Per Share Dividend (in dollars per share)	$ 0.28
Record Date	May 15, 2020
Total Amount	$ 5,647
Payment Date	May 22, 2020
Dividend Declared July 20, 2020 [Member]
Declaration Date	Jul. 20, 2020
Per Share Dividend (in dollars per share)	$ 0.28
Record Date	Jul. 31, 2020
Total Amount	$ 5,647
Payment Date	Aug. 07, 2020
Dividend Declared October 26, 2020 [Member]
Declaration Date	Oct. 26, 2020
Per Share Dividend (in dollars per share)	$ 0.28
Record Date	Nov. 09, 2020
Total Amount	$ 5,676
Payment Date	Nov. 20, 2020
Dividend Declared January 19, 2021 [Member]
Declaration Date	Jan. 19, 2021
Per Share Dividend (in dollars per share)	$ 0.28
Record Date	Feb. 01, 2021
Total Amount	$ 5,676
Payment Date	Feb. 12, 2021