Investments (Available For Sale Securities Unrealized Loss Position) (Details) (USD $) In Thousands	Jun. 25, 2011	Dec. 25, 2010
Available-for-sale securities, continuous unrealized loss position, Less than 12 months, Fair Value		$ 12,614
Available-for-sale securities, continuous unrealized loss position, Less than 12 months, Unrealized Loss		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		12,614
Available-for-sale securities, continuous unrealized loss position, Unrealized Loss, Total		182
Mortgage-Backed Securities [Member]
Available-for-sale securities, continuous unrealized loss position, Less than 12 months, Fair Value		225
Available-for-sale securities, continuous unrealized loss position, Less than 12 months, Unrealized Loss		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		225
Available-for-sale securities, continuous unrealized loss position, Unrealized Loss, Total		8
Corporate Bonds And Direct Obligations Of Government Agencies [Member]
Available-for-sale securities, continuous unrealized loss position, Less than 12 months, Fair Value	2,143	11,615
Available-for-sale securities, continuous unrealized loss position, Less than 12 months, Unrealized Loss	8	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	2,143	11,615
Available-for-sale securities, continuous unrealized loss position, Unrealized Loss, Total	8	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