Note 10 - Employee Equity Incentive Plans - Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended
		Jun. 30, 2017	Mar. 31, 2017
Options outstanding, beginning of period (in shares)		5,097,545
Weighted average exercise price per share, beginning balance (in dollars per share)		$ 10.71
Options oustanding, Options granted (in shares)		549,000
Weighted average exercise price per share, Options granted (in dollars per share)		$ 16.05
Options oustanding, Options exercised (in shares)		(812,045)
Weighted average exercise price per share, Options exercised (in dollars per share)		$ 9.40
Options exercised, Intrinsic Value	[1]	$ 5,187
Options oustanding, Options cancelled (in shares)		(89,750)
Weighted average exercise price per share, Options cancelled (in dollars per share)		$ 11.42
Options oustanding, Options expired (in shares)		(19,000)
Weighted average exercise price per share, Options expired (in dollars per share)		$ 9.35
Options oustanding, ending balance (in shares)		4,725,750
Weighted average exercise price per share, ending balance (in dollars per share)		$ 11.54
Options exercisable (in shares)		2,607,500	3,300,295
Weighted average exercise price per share, exercisable (in dollars per share)		$ 10.75	$ 10.34

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