Note 6 - Calculation of Earnings Per Share (Details) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Net income	$ 2,149	$ 4,696	$ 8,116	$ 10,951
Basic (in shares)	31,522	30,590	31,429	30,533
Dilutive effect of equity incentive plans (in shares)	878	1,292	916	1,390
Diluted (in shares)	32,400	31,882	32,345	31,923
Basic (in dollars per share)	$ 0.07	$ 0.15	$ 0.26	$ 0.36
Diluted (in dollars per share)	$ 0.07	$ 0.15	$ 0.25	$ 0.34