Note H - Income Taxes - Reconciliation of Statutory Rate to Effective Rate (Details)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Statutory rate	21.00%	21.00%	21.00%
State tax, net of federal benefit	0.10%	0.00%	2.30%
Research and development credit	(1.80%)	(2.10%)	(2.00%)
Adjustment for prior year estimates	(0.60%)	1.20%	0.10%
Foreign-derived intangible income	(0.30%)	(0.20%)	(0.20%)
Tax exempt interest and dividends	0.00%	(0.10%)	(0.10%)
Other	0.20%	0.40%	(0.10%)
Effective rate	18.60%	20.20%	21.00%