Note 11 - 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, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Net income	$ 3,463	$ 3,935	$ 8,957	$ 6,954
Weighted average shares - basic (in shares)	32,642	31,490	32,364	31,447
Weighted average shares - diluted (in shares)	34,099	32,145	33,572	32,074
Basic (in dollars per share)	$ 0.11	$ 0.12	$ 0.28	$ 0.22
Diluted (in dollars per share)	$ 0.10	$ 0.12	$ 0.27	$ 0.22