Note G - Cash, Cash Equivalents And Marketable Securities - Summary of Marketable Securities (Details) - USD ($) $ in Thousands	Jul. 04, 2021	Dec. 31, 2020
Amortized Cost	$ 42,375	$ 68,785
Fair Value	42,465	68,981
Gross Unrealized Gains	90	196
Gross Unrealized Losses	0	0
Nontaxable Municipal Bonds [Member]
Amortized Cost	16,835	42,817
Fair Value	16,925	43,013
Gross Unrealized Gains	90	196
Gross Unrealized Losses	0	0
Variable Rate Demand Obligation [Member]
Amortized Cost	25,540	25,968
Fair Value	25,540	25,968
Gross Unrealized Gains	0	0
Gross Unrealized Losses	$ 0	$ 0