Note 4 - Components of Common Shares Outstanding (Details) - shares	3 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Weighted average common shares outstanding – basic (in shares)	4,835,010	4,854,841
Dilutive effect of stock options (in shares)	2,085	6,007
Shares used in computing net income per share – diluted (in shares)	4,837,095	4,860,848