Note D - Stock-based Compensation - Stock Option Activity by Exercise Price (Details)	9 Months Ended
	Sep. 30, 2016 $ / shares shares
Exercise Price 1 [Member]
Exercise price (in dollars per share) | $ / shares	$ 10.44
Shares under outstanding options (in shares)	15,000
Weighted-average remaining contractual term	1 year 146 days
Shares under exercisable options (in shares)	15,000
Exercise Price 2 [Member]
Exercise price (in dollars per share) | $ / shares	$ 10.90
Shares under outstanding options (in shares)	6,000
Weighted-average remaining contractual term	219 days
Shares under exercisable options (in shares)	6,000
Exercise Price 3 [Member]
Exercise price (in dollars per share) | $ / shares	$ 10.90
Shares under outstanding options (in shares)	26,600
Weighted-average remaining contractual term	5 years 255 days
Shares under exercisable options (in shares)	13,800
Exercise Price 4 [Member]
Exercise price (in dollars per share) | $ / shares	$ 11.22
Shares under outstanding options (in shares)	5,998
Weighted-average remaining contractual term	4 years 73 days
Shares under exercisable options (in shares)	5,998
Exercise Price 5 [Member]
Exercise price (in dollars per share) | $ / shares	$ 11.54
Shares under outstanding options (in shares)	4,000
Weighted-average remaining contractual term	146 days
Shares under exercisable options (in shares)	4,000
Shares under outstanding options (in shares)	57,598
Weighted-average remaining contractual term	3 years 182 days
Shares under exercisable options (in shares)	44,798