Note 4 - Components of Common Shares Outstanding (Details) - shares	3 Months Ended		9 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2015	Dec. 31, 2014
Basic (in shares)	4,844,845	4,857,953	4,853,970	4,854,702
Dilutive effect of stock options (in shares)	2,125	18,121	3,133	16,568
Shares used in computing net income per share – diluted (in shares)	4,846,970	4,876,074	4,857,103	4,871,270