Note 10 - Net Income Per Share (Details) - Net Income Per Share Basic And Diluted (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Numerator:
Net income (in Dollars)	$ 8,860	$ 11,221	$ 6,397	$ 9,018	$ 7,499	$ 7,410	$ 5,489	$ 2,499	$ 35,495	$ 22,898	$ 15,756
Denominator:
Weighted-average outstanding shares used to compute basic net income per share									38,686	37,387	34,871
Effect of dilutive securities									1,107	1,233	1,376
Weighted-average outstanding shares used to compute diluted net income per share	40,321	39,727	39,608	39,517	39,524	39,009	38,239	37,708	39,793	38,620	36,247
Net income per share:
Basic (in Dollars per share)	$ 0.23	$ 0.29	$ 0.17	$ 0.23	$ 0.20	$ 0.20	$ 0.15	$ 0.07	$ 0.92	$ 0.61	$ 0.45
Diluted (in Dollars per share)	$ 0.22	$ 0.28	$ 0.16	$ 0.23	$ 0.19	$ 0.19	$ 0.14	$ 0.07	$ 0.89	$ 0.59	$ 0.43