Note F - Fair Value Measurements - Assets Measured at Fair Value on Recurring Basis (Details) - Fair Value, Recurring [Member] - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Equity Securities [Member]
Assets, Fair Value Disclosure	$ 58	$ 68
Equity Mutual Fund [Member]
Assets, Fair Value Disclosure	16,585	16,294
Commodity Mutual Fund [Member]
Assets, Fair Value Disclosure	244	222
U S Treasury Mutual Fund [Member]
Assets, Fair Value Disclosure	20,941	17,722
Fair Value, Inputs, Level 1 [Member] | Equity Securities [Member]
Assets, Fair Value Disclosure	58	68
Fair Value, Inputs, Level 1 [Member] | U S Treasury Mutual Fund [Member]
Assets, Fair Value Disclosure	20,941	17,722
Fair Value, Inputs, Level 2 [Member] | Equity Securities [Member]
Assets, Fair Value Disclosure		0
Fair Value, Inputs, Level 2 [Member] | Equity Mutual Fund [Member]
Assets, Fair Value Disclosure	16,585	16,294
Fair Value, Inputs, Level 2 [Member] | Commodity Mutual Fund [Member]
Assets, Fair Value Disclosure	$ 244	$ 222