Note 2 - Summary of Significant Accounting Policies (Detail) - Stock Option Activity (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Outstanding - Number of options	7,371,304	5,058,525	1,323,782
Outstanding - Weighted average exercise price (in Dollars per share)	$ 12.48	$ 7.29	$ 3.02
Outstanding - Weighted average remaining contractual life	8 years 36 days
Exercisable at December 31, 2012	4,178,446
Exercisable at December 31, 2012 (in Dollars per share)	$ 9.62
Exercisable at December 31, 2012	7 years 109 days
Expected to vest after December 31, 2012	4,703,838
Expected to vest after December 31, 2012 (in Dollars per share)	$ 13.48
Expected to vest after December 31, 2012	8 years 292 days
Options granted - Number	2,933,701	3,173,900	4,172,687
Options granted - Weighted average exercise price (in Dollars per share)	$ 10.28	$ 19.64	$ 8.45
Options forfeited - Number	(552,228)	(402,220)	(242,633)
Options forfeited - Weighted average exercise price (in Dollars per share)	$ 15.28	$ 12.22	$ 6.88
Options exercised - Number	(289,120)	(458,901)	(195,311)
Options exercised- Weighted average exercise price (in Dollars per share)	$ 8.46	$ 5.00	$ 3.50
Outstanding - Number of options	9,463,657	7,371,304	5,058,525
Outstanding - Weighted average exercise price (in Dollars per share)	$ 11.76	$ 12.48	$ 7.29