Note 6 - Net Income Per Share (Details) - Net Income Per Share Basic And Diluted (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Numerator:
Net income (in Dollars)	$ 5,963	$ 9,018
Denominator:
Weighted-average outstanding shares used to compute basic net income per share	39,105	38,470
Effect of dilutive securities	1,491	1,047
Weighted-average outstanding shares used to compute diluted net income per share	40,596	39,517
Net income per share:
Basic (in Dollars per share)	$ 0.15	$ 0.23
Diluted (in Dollars per share)	$ 0.15	$ 0.23