Note F - Stock-based Compensation - Activity for Non-vested Restricted Stock (Details) - Restricted Stock [Member] - $ / shares	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Non-vested, shares (in shares)	29,671	32,336	28,934
Non-vested, weighted average fair value at grant date (in dollars per share)	$ 88.37	$ 89.49	$ 95.54
Granted, shares (in shares)	4,228	1,487	7,271
Granted, weighted average fair value at grant date (in dollars per share)	$ 78.78	$ 77.03	$ 70.72
Vested, shares (in shares)	(3,234)	(4,109)	(3,482)
Vested, weighted average fair value at grant date (in dollars per share)	$ 121.11	$ 68.46	$ 100.05
Forfeited, shares (in shares)	0	(43)	(387)
Forfeited, weighted average fair value at grant date (in dollars per share)	$ 0	$ 93.29	$ 93.91
Non-vested, shares (in shares)	30,665	29,671	32,336
Non-vested, weighted average fair value at grant date (in dollars per share)	$ 83.6	$ 88.37	$ 89.49