Note 5 - Net Income Per Share Basic and Diluted (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Numerator:
Net income	$ 10,575	$ 5,963
Denominator:
Weighted-average outstanding shares used to compute basic net income per share (in shares)	40,028	39,105
Effect of dilutive securities (in shares)	1,618	1,491
Weighted-average outstanding shares used to compute diluted net income per share (in shares)	41,646	40,596
Basic (in dollars per share)	$ 0.26	$ 0.15
Diluted (in dollars per share)	$ 0.25	$ 0.15