Note 13 - Computation of Earnings Per Share - Computation of Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Net income	$ 3,935	$ 3,273	$ 6,954	$ 6,258
Weighted average shares - basic (in shares)	31,490	31,651	31,447	31,769
Weighted average shares - diluted (in shares)	32,145	32,380	32,074	32,627
Net income per share - basic (in dollars per share)	$ 0.12	$ 0.10	$ 0.22	$ 0.20
Net income per share - diluted (in dollars per share)	$ 0.12	$ 0.10	$ 0.22	$ 0.19