Note D - Stock-based Compensation - Stock Option Activity (Details)	6 Months Ended
	Jun. 30, 2017 USD ($) $ / shares shares
Outstanding (in shares) | shares	56,131
Outstanding (in dollars per share) | $ / shares	$ 10.85
Exercised (in shares) | shares	(10,000)
Exercised (in dollars per share) | $ / shares	$ 11.16
Outstanding (in dollars per share) | $ / shares	$ 10.79
Outstanding (Year)	3 years 146 days
Outstanding | $	$ 376,485	[1]
Options exercisable (in shares) | shares	46,131
Options exercisable (in dollars per share) | $ / shares	$ 10.79
Fully vested and exercisable (Year)	3 years 146 days
Outstanding (in shares) | shares	46,131
Fully vested and exercisable | $	$ 376,485	[1]

[1] The intrinsic value of a stock option is the amount by which the market value of the underlying stock exceeds the exercise price of the option. The per share market value of our common stock, as determined by the closing price on June 30, 2017, was $18.95.