Marketable Securities (Available For Sale Securities) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 27, 2014	Dec. 28, 2013
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost, Total	$ 65,759	$ 56,401
Gross Unrealized Holding Gains	8,296	7,925
Gross Unrealized Holding Losses	(96)	(1,233)
Fair Value	73,959us-gaap_AvailableForSaleSecurities	63,093us-gaap_AvailableForSaleSecurities
Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost, Total	1,198	970
Gross Unrealized Holding Gains	6,683	7,239
Gross Unrealized Holding Losses	0	0
Fair Value	7,881	8,209
Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost, Total	64,561	55,431
Gross Unrealized Holding Gains	1,613	686
Gross Unrealized Holding Losses	(96)	(1,233)
Fair Value	$ 66,078	$ 54,884

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

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

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

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