Note 12 - Employee Equity Incentive Plans - Stock-based Compensation in Income Tax Provision (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2016	Dec. 31, 2015
Stock-based Compensation Effect in Income before Taxes		$ 822	$ 838	$ 2,551	$ 2,777
Provision for income tax	[1]	329	293	1,021	972
Net stock-based compensation effects in net income		493	545	1,530	1,805
Cost of Sales [Member]
Stock-based Compensation Effect in Income before Taxes		80	125	276	371
Research and Development Expense [Member]
Stock-based Compensation Effect in Income before Taxes		254	242	840	1,032	[2]
Selling, General and Administrative Expenses [Member]
Stock-based Compensation Effect in Income before Taxes		$ 488	$ 471	$ 1,435	$ 1,374

[1] Calculated at the U.S. statutory income tax rate of 40% in fiscal 2017 and 35% in fiscal 2016.

[2] Includes acquisition related compensation expenses of $249,000 during the nine months ended December 31, 2015.