Note H - Earnings Per Share - Computations of Basic and Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019
Net income	$ 6,000	$ (823)	$ (1,304)	$ 4,581	$ 8,654	$ 8,301	$ 3,874	$ 21,536
Basic (in shares)	5,763			5,756			5,758	5,859
Dilutive effect of common stock equivalents (in shares)	5			43			17	48
Diluted weighted average common shares outstanding (in shares)	5,768			5,799			5,775	5,907
Basic (in dollars per share)	$ 1.04			$ 0.80			$ 0.67	$ 3.68
Diluted (in dollars per share)	$ 1.04			$ 0.79			$ 0.67	$ 3.65