Note 2 - Summary of Significant Accounting Policies (Details) - Stock Option Activity $ / shares in Units, $ in Thousands	9 Months Ended
	Sep. 30, 2015 USD ($) $ / shares shares
Stock Option Activity [Abstract]
Outstanding at December 31, 2014 | shares	4,965,947
Outstanding at December 31, 2014	$ 12.96
Outstanding at September 30, 2015 | shares	3,835,775
Outstanding at September 30, 2015	$ 13.27
Exercisable at September 30, 2015 | shares	3,361,732
Exercisable at September 30, 2015	$ 10.74
Exercisable at September 30, 2015	5 years 6 months
Exercisable at September 30, 2015 | $	$ 62,747
Options granted | shares	35,000
Options granted	$ 40.20
Options forfeited | shares	(49,881)
Options forfeited	$ 22.96
Options exercised | shares	(1,115,291)
Options exercised	$ 12.32