Note 7 - Changes in Shareholders' Equity - Schedule of Changes in Shareholders' Equity (Details) - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Balance	$ 130,010
Net income	7,768	$ 5,343
Repurchase and retirement of common stock		(11,500)
Balance	132,871
Additional Paid-in Capital [Member]
Balance	3,804	12,478
Share based compensation	740	635
Dividends declared	0	0
Net income	0	0
Repurchase and retirement of common stock		(11,496)
Balance	4,544	1,617
Retained Earnings [Member]
Balance	126,177	122,172
Share based compensation	0	0
Dividends declared	(5,647)	(5,518)
Net income	7,768	5,343
Repurchase and retirement of common stock		0
Balance	$ 128,298	$ 121,997