Note 2 - Summary of Significant Accounting Policies (Details) - Stock Option Activity (USD $) In Thousands, except Share data, unless otherwise specified	6 Months Ended
	Jun. 30, 2014
Stock Option Activity [Abstract]
Outstanding at December 31, 2013	7,334,745
Outstanding at December 31, 2013	$ 12.33
Outstanding at June 30, 2014	5,952,784
Outstanding at June 30, 2014	$ 13.36
Exercisable at June 30, 2014	4,484,129
Exercisable at June 30, 2014	$ 11.65
Exercisable at June 30, 2014	6 years 219 days
Exercisable at June 30, 2014	$ 90,039
Options granted	453,125
Options granted	$ 31.54
Options forfeited	(109,268)
Options forfeited	$ 18.72
Options exercised	(1,725,818)
Options exercised	$ 13.40