Note 12 - Computation of Earnings Per Share - Computation of Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended																12 Months Ended
	Mar. 31, 2017		Dec. 31, 2016		Sep. 30, 2016		Jun. 30, 2016		Mar. 31, 2016		Dec. 31, 2015		Sep. 30, 2015		Jun. 30, 2015		Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Net income	$ 9,294		$ 5,100		$ 3,935		$ 3,019		$ 6,197	[1]	$ 2,286	[1]	$ 3,273	[1]	$ 2,985	[1]	$ 21,348	$ 14,741	$ 23,740
Weighted average shares - basic (in shares)	31,724		31,558		31,490		31,401		31,441		31,487		31,651		31,746		31,544	31,579	31,531
Weighted average shares - diluted (in shares)	32,635		32,209		32,145		32,001		32,076		32,343		32,380		32,733		32,248	32,381	32,239
Net income per share - basic (in dollars per share)	$ 0.29	[2]	$ 0.16	[2]	$ 0.12	[2]	$ 0.10	[2]	$ 0.20	[2]	$ 0.07	[2]	$ 0.10	[2]	$ 0.09	[2]	$ 0.68	$ 0.47	$ 0.75
Net income per share - diluted (in dollars per share)	$ 0.28	[2]	$ 0.16	[2]	$ 0.12	[2]	$ 0.09	[2]	$ 0.19	[2]	$ 0.07	[2]	$ 0.10	[2]	$ 0.09	[2]	$ 0.66	$ 0.46	$ 0.74

[1] During the fiscal year ended March 31, 2016, we recorded out-of-period adjustments that increased the income tax provision by a net amount of $1.4 million. See Note 16, "Income Taxes" in the Notes to Consolidated Financial Statements in Item 8 of this Annual Report on Form 10-K for further discussion of an out-of-period adjustment during the quarter ended December 31, 2015.

[2] The sum of the four quarterly calculations of net income per share is not equal to the annual net income per share due to the use of quarterly weighted average shares used to determine the quarterly net income per share as compared to the annual weighted average shares used to determine the annual net income per share.