Note 11 - Employee Equity Incentive Plans - Fair Value and Assumptions (Details) - $ / shares		9 Months Ended
		Dec. 31, 2015	Dec. 31, 2014
Employee Stock Option [Member]
Weighted average estimated fair value of grant per share (in dollars per share)	[1]	$ 4.83	$ 5.54
Risk-free interest rate	[1]	1.80%	1.80%
Expected term in years	[1]	6 years 164 days	6 years 109 days
Volatility	[1]	44.90%	52.20%
Dividend yield	[1]	1.20%	1.00%
Employee Stock Purchase Plan 1999 [Member]
Weighted average estimated fair value of grant per share (in dollars per share)	[2]	$ 3.54	$ 2.90
Risk-free interest rate	[2]	0.10%	0.10%
Expected term in years	[2]	182 days	182 days
Volatility	[2]	48.20%	36.90%
Dividend yield	[2]	1.20%	1.10%

[1] No stock options were granted during the quarter ended December 31, 2015 and 2014.

[2] Under the stock purchase plan, rights to purchase shares are only granted during the first and third quarters of each fiscal year.