Note K - Stock Options Outstanding, by Exercise Price Range (Details)	12 Months Ended
	Dec. 31, 2015 $ / shares shares
Price Range 1 [Member]
Range of Exercise Prices, Lower range (in dollars per share)	$ 9.05
Range of Exercise Prices, Upper range (in dollars per share)	$ 25
Number Outstanding (in Shares) (in shares) | shares	210,293
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term	4 years 200 days
Weighted Average Exercise Price (in dollars per share)	$ 22.61
Exercisable at December 31, 2015 (in shares) | shares	210,293
Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 22.61
Price Range 2 [Member]
Range of Exercise Prices, Lower range (in dollars per share)	25.01
Range of Exercise Prices, Upper range (in dollars per share)	$ 28
Number Outstanding (in Shares) (in shares) | shares	345,851
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term	6 years 288 days
Weighted Average Exercise Price (in dollars per share)	$ 26.46
Exercisable at December 31, 2015 (in shares) | shares	274,368
Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 26.31
Price Range 3 [Member]
Range of Exercise Prices, Lower range (in dollars per share)	28.01
Range of Exercise Prices, Upper range (in dollars per share)	$ 41
Number Outstanding (in Shares) (in shares) | shares	166,861
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term	8 years 76 days
Weighted Average Exercise Price (in dollars per share)	$ 40.68
Exercisable at December 31, 2015 (in shares) | shares	55,626
Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 40.68
Price Range 4 [Member]
Range of Exercise Prices, Lower range (in dollars per share)	9.05
Range of Exercise Prices, Upper range (in dollars per share)	$ 41
Number Outstanding (in Shares) (in shares) | shares	723,005
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term	6 years 171 days
Weighted Average Exercise Price (in dollars per share)	$ 28.62
Exercisable at December 31, 2015 (in shares) | shares	540,287
Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 26.35
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term	10 years