Note 6 - Stock-Based Compensation (Details) - Changes In Shares Under Option Plans (USD $)	1 Months Ended	3 Months Ended
	Feb. 28, 2014	Mar. 31, 2014	Mar. 31, 2013
Changes In Shares Under Option Plans [Abstract]
Beginning Balance		501,334	722,155
Beginning Balance		$ 10.34	$ 10.18
Issued	21,000	21,000	3,300
Issued		$ 32.77	$ 20.03
Exercised		(19,027)	(52,480)
Exercised		$ 13.13	$ 8.91
Forfeited		(110)	(330)
Forfeited		$ 5.76	$ 5.76
Expired		(408)	(15,640)
Expired		$ 9.37	$ 10.79
Ending Balance		502,789	657,005
Ending Balance		$ 11.18	$ 10.32