Note 4 - Stockholders' Equity (Details) - Stock Options Activity (USD $) In Thousands, except Per Share data, unless otherwise specified	6 Months Ended
	Jun. 30, 2013
Stock Options Activity [Abstract]
Outstanding - Number of Options	3,810
Outstanding - Weighted Average Exercise Price per Share (in Dollars per share)	$ 6.91
Outstanding - Weighted Average Remaining Contractual Term	7 years 18 days
Vested and expected to vest, June 30, 2013	3,181
Vested and expected to vest, June 30, 2013 (in Dollars per share)	$ 7.05
Vested and expected to vest, June 30, 2013	6 years 350 days
Vested and expected to vest, June 30, 2013 (in Dollars)	$ 36,191
Exercisable, June 30, 2013	1,890
Exercisable, June 30, 2013 (in Dollars per share)	$ 6.57
Exercisable, June 30, 2013	6 years 3 days
Exercisable, June 30, 2013 (in Dollars)	22,416
Expired	(16)
Expired (in Dollars per share)	$ 5.44
Granted	63
Granted (in Dollars per share)	$ 15.83
Exercised	(427)
Exercised (in Dollars per share)	$ 6.51
Canceled	(72)
Canceled (in Dollars per share)	$ 6.93
Outstanding - Number of Options	3,358
Outstanding - Weighted Average Exercise Price per Share (in Dollars per share)	$ 7.12
Outstanding - Aggregate Intrinsic Value (in Dollars)	$ 37,964