Note 6 - Stockholders' Equity and Equity Compensation (Detail) - Summary of Stock Option Activity (USD $)	3 Months Ended
	Mar. 31, 2013
Outstanding at January 1, 2013	1,223,618
Outstanding at January 1, 2013 (in Dollars per share)	$ 18.49
Granted	29,025
Granted (in Dollars per share)	$ 25.11
Exercised	(29,511)
Exercised (in Dollars per share)	$ 20.14
Canceled	(3,150)
Canceled (in Dollars per share)	$ 19.41
Outstanding at March 31, 2013	1,219,982
Outstanding at March 31, 2013 (in Dollars per share)	$ 18.61
Exercisable at March 31, 2013	939,209
Exercisable at March 31, 2013 (in Dollars per share)	$ 17.92