Note E - Stock Based Compensation - Stock Option Activity by Exercise Price (Details)	3 Months Ended
	Mar. 31, 2018 $ / shares shares
Shares under outstanding options (in shares)	29,005
Weighted-average remaining contractual term (Year)	3 years 328 days
Shares under exercisable options (in shares)	29,005
Exercise Price 1 [Member]
Exercise price (in dollars per share) | $ / shares	$ 10.90
Shares under outstanding options (in shares)	23,600
Weighted-average remaining contractual term (Year)	4 years 73 days
Shares under exercisable options (in shares)	23,600
Exercise Price 2 [Member]
Exercise price (in dollars per share) | $ / shares	$ 11.22
Shares under outstanding options (in shares)	5,405
Weighted-average remaining contractual term (Year)	2 years 255 days
Shares under exercisable options (in shares)	5,405