Marketable Securities (Schedule Of Marketable Securities) (Details) - USD ($) $ in Thousands	Sep. 28, 2019	Dec. 29, 2018
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 49,633	$ 46,699
Gross Unrealized Holding Gains	2,060	426
Gross Unrealized Holding Losses	(11)	(53)
Fair value	60,544	54,298
Equity Securities [Member] \| Fair Value, Inputs, Level 1 [Member]
Debt Securities, Available-for-sale [Line Items]
Equity securities, Fair Value	8,862	7,226
Municipal Bonds [Member] \| Fair Value, Inputs, Level 2 [Member]
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	49,633	46,699
Gross Unrealized Holding Gains	2,060	426
Gross Unrealized Holding Losses	(11)	(53)
Fair Value	$ 51,682	$ 47,072

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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