Investments (Schedule Of Unrealized Loss On Investments) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 25, 2010
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale investments with unrealized losses, Less than 12 months, Fair Market Value	$ 7,126	$ 12,614
Available-for-sale investments with unrealized losses, Less than 12 months, Unrealized Loss	145	182
Available-for-sale investments with unrealized losses, 12 months or longer, Fair Market Value
Available-for-sale investments with unrealized losses, 12 months or longer, Unrealized Loss
Available-for-sale investments with unrealized losses, Fair Market Value, Total	7,126	12,614
Available-for-sale investments with unrealized losses, Unrealized Loss, Total	145	182
Mortgage-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale investments with unrealized losses, Less than 12 months, Fair Market Value	468	225
Available-for-sale investments with unrealized losses, Less than 12 months, Unrealized Loss	18	8
Available-for-sale investments with unrealized losses, 12 months or longer, Fair Market Value
Available-for-sale investments with unrealized losses, 12 months or longer, Unrealized Loss
Available-for-sale investments with unrealized losses, Fair Market Value, Total	468	225
Available-for-sale investments with unrealized losses, Unrealized Loss, Total	18	8
Corporate Bonds And Direct Obligations Of Government Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale investments with unrealized losses, Less than 12 months, Fair Market Value	6,067	11,615
Available-for-sale investments with unrealized losses, Less than 12 months, Unrealized Loss	126	151
Available-for-sale investments with unrealized losses, 12 months or longer, Fair Market Value
Available-for-sale investments with unrealized losses, 12 months or longer, Unrealized Loss
Available-for-sale investments with unrealized losses, Fair Market Value, Total	6,067	11,615
Available-for-sale investments with unrealized losses, Unrealized Loss, Total	126	151
U.S. Treasury Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale investments with unrealized losses, Less than 12 months, Fair Market Value	591	774
Available-for-sale investments with unrealized losses, Less than 12 months, Unrealized Loss	1	23
Available-for-sale investments with unrealized losses, 12 months or longer, Fair Market Value
Available-for-sale investments with unrealized losses, 12 months or longer, Unrealized Loss
Available-for-sale investments with unrealized losses, Fair Market Value, Total	591	774
Available-for-sale investments with unrealized losses, Unrealized Loss, Total	$ 1	$ 23