Marketable Securities (Schedule Of Marketable Securities) (Details) - USD ($) $ in Thousands	Sep. 29, 2018	Dec. 30, 2017
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 48,853	$ 55,476
Gross Unrealized Holding Gains	6,901	8,305
Gross Unrealized Holding Losses	(414)	(116)
Fair Value	55,340	63,665
Equity Securities [Member] \| Fair Value, Inputs, Level 1 [Member]
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1,198	1,198
Gross Unrealized Holding Gains	6,750	7,634
Gross Unrealized Holding Losses	0	0
Fair Value	7,948	8,832
Municipal Bonds [Member] \| Fair Value, Inputs, Level 2 [Member]
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	47,655	54,278
Gross Unrealized Holding Gains	151	671
Gross Unrealized Holding Losses	(414)	(116)
Fair Value	$ 47,392	$ 54,833

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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- Definition

Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27161-111563

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- Definition

Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

+ References

No definition available.

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- Definition

This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

+ References

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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