Note 10 - Employee Equity Incentive Plans - Option Activity (Details) - USD ($) $ in Thousands		6 Months Ended
		Sep. 30, 2015	Mar. 31, 2015
Options outstanding (in shares)		5,308,397
Options outstanding (in dollars per share)		$ 10.38
Options granted (in shares)		1,124,000
Options granted (in dollars per share)		$ 11.72
Options exercised (in shares)		(320,826)
Options exercised (in dollars per share)		$ 9.15
Options exercised, Intrinsic Value	[1]	$ 1,291
Options cancelled (in shares)		(2,500)
Options cancelled (in dollars per share)		$ 12.13
Options expired (in shares)		(434,788)
Options expired (in dollars per share)		$ 14.68
Options exercisable (in shares)		3,504,063	3,942,261
Options exercisable (in dollars per share)		$ 9.84	$ 10.20

[1] Represents the difference between the exercise price and the value of our common stock at the time of exercise.