Note 2 - Summary of Significant Accounting Policies (Details) - Stock Option Activity (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2014
Stock Option Activity [Abstract]
Outstanding at December 31, 2013	7,334,745
Outstanding at December 31, 2013	$ 12.33
Outstanding at March 31, 2014	6,743,885
Outstanding at March 31, 2014	$ 13.13
Exercisable at March 31, 2014	4,992,036
Exercisable at March 31, 2014	$ 11.20
Exercisable at March 31, 2014	6 years 255 days
Exercisable at March 31, 2014	$ 118,849
Options granted	448,125
Options granted	$ 31.51
Options forfeited	(65,839)
Options forfeited	$ 20.34
Options exercised	(973,146)
Options exercised	$ 14.58