Financial Instruments (Schedule Of Fixed Income Securities In Unrealized Loss Positions) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 25, 2011
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Unrealized Losses Less Than 12 Months - Fair Value	$ 158,317
Unrealized Losses Less Than 12 Months - Gross Unrealized Loss	(858)
Unrealized Losses 12 Months or Greater - Fair Value	966
Unrealized Losses 12 Months or Greater - Gross Unrealized Loss	(46)
Total - Fair Value	159,283
Total - Gross Unrealized Loss	(904)
Municipal Notes And Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Unrealized Losses Less Than 12 Months - Fair Value	26,581
Unrealized Losses Less Than 12 Months - Gross Unrealized Loss	(24)
Total - Fair Value	26,581
Total - Gross Unrealized Loss	(24)
Government-Sponsored Enterprises [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Unrealized Losses Less Than 12 Months - Fair Value	19,449
Unrealized Losses Less Than 12 Months - Gross Unrealized Loss	(34)
Total - Fair Value	19,449
Total - Gross Unrealized Loss	(34)
Corporate Notes And Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Unrealized Losses Less Than 12 Months - Fair Value	86,980
Unrealized Losses Less Than 12 Months - Gross Unrealized Loss	(584)
Total - Fair Value	86,980
Total - Gross Unrealized Loss	(584)
Mortgage Backed Securities- Commercial [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Unrealized Losses Less Than 12 Months - Fair Value	25,307
Unrealized Losses Less Than 12 Months - Gross Unrealized Loss	(216)
Unrealized Losses 12 Months or Greater - Fair Value	966
Unrealized Losses 12 Months or Greater - Gross Unrealized Loss	(46)
Total - Fair Value	26,273
Total - Gross Unrealized Loss	$ (262)