Note 4 - Stockholders' Equity (Detail) - Stock Options Activity (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013
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 76 days
Vested and expected to vest, March 31, 2013	3,418
Vested and expected to vest, March 31, 2013 (in Dollars per share)	$ 6.96
Vested and expected to vest, March 31, 2013	7 years 40 days
Vested and expected to vest, March 31, 2013 (in Dollars)	$ 30,980
Exercisable, March 31, 2013	1,913
Exercisable, March 31, 2013 (in Dollars per share)	$ 6.58
Exercisable, March 31, 2013	6 years 7 days
Exercisable, March 31, 2013 (in Dollars)	18,065
Expired	(14)
Expired (in Dollars per share)	$ 5.39
Granted	48
Granted (in Dollars per share)	$ 15.95
Exercised	(170)
Exercised (in Dollars per share)	$ 6.90
Canceled	(38)
Canceled (in Dollars per share)	$ 6.59
Outstanding - Number of Options	3,636
Outstanding - Weighted Average Exercise Price per Share (in Dollars per share)	$ 7.03
Outstanding - Aggregate Intrinsic Value (in Dollars)	$ 32,687