Note 5 - Net Income per Common Share (Details) - Computation of Basic and Diluted Net Income per Share (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Computation of Basic and Diluted Net Income per Share [Abstract]
Net income (in Dollars)	$ 10,956	$ 8,611	$ 21,058	$ 16,898
Basic - weighted-average shares outstanding:	25,620,005	25,258,932	25,597,055	25,030,283
Effect of dilutive securities:
Employee stock options and other	526,843	591,315	535,210	597,099
Diluted - weighted-average shares outstanding:	26,146,848	25,850,247	26,132,265	25,627,382
Net income per share:
Basic (in Dollars per share)	$ 0.43	$ 0.34	$ 0.82	$ 0.68
Diluted (in Dollars per share)	$ 0.42	$ 0.33	$ 0.81	$ 0.66