Investments (Schedule Of Unrealized Loss On Investments) (Details) (USD $) In Thousands	Sep. 24, 2011	Dec. 25, 2010
Available-for-sale securities, continuous unrealized loss position, Less than 12 months, Fair Value	$ 4,917	$ 12,614
Available-for-sale securities, continuous unrealized loss position, Less than 12 months, Unrealized Loss	95	182
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, Fair Value
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, Unrealized Loss
Available-for-sale securities, continuous unrealized loss position, Fair Value, Total	4,917	12,614
Available-for-sale securities, continuous unrealized loss position, Unrealized Loss, Total	95	182
Mortgage-Backed Securities [Member]
Available-for-sale securities, continuous unrealized loss position, Less than 12 months, Fair Value	1,405	225
Available-for-sale securities, continuous unrealized loss position, Less than 12 months, Unrealized Loss	22	8
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, Fair Value
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, Unrealized Loss
Available-for-sale securities, continuous unrealized loss position, Fair Value, Total	1,405	225
Available-for-sale securities, continuous unrealized loss position, Unrealized Loss, Total	22	8
Corporate Bonds And Direct Obligations Of Government Agencies [Member]
Available-for-sale securities, continuous unrealized loss position, Less than 12 months, Fair Value	3,512	11,615
Available-for-sale securities, continuous unrealized loss position, Less than 12 months, Unrealized Loss	73	151
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, Fair Value
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, Unrealized Loss
Available-for-sale securities, continuous unrealized loss position, Fair Value, Total	3,512	11,615
Available-for-sale securities, continuous unrealized loss position, Unrealized Loss, Total	73	151
U.S. Treasury Obligations [Member]
Available-for-sale securities, continuous unrealized loss position, Less than 12 months, Fair Value		774
Available-for-sale securities, continuous unrealized loss position, Less than 12 months, Unrealized Loss		23
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, Fair Value
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, Unrealized Loss
Available-for-sale securities, continuous unrealized loss position, Fair Value, Total		774
Available-for-sale securities, continuous unrealized loss position, Unrealized Loss, Total		$ 23