Investments (Available-For-Sale Investments) (Details) (USD $)	9 Months Ended	12 Months Ended
	Sep. 24, 2011	Dec. 25, 2010
Net unrealized gains on the investments	$ 990,000	$ 760,000
Amortized Cost	69,239,000	76,907,000
Gross Unrealized Gains	1,085,000	942,000
Gross Unrealized Losses	95,000	182,000
Fair Market Value	70,229,000	77,667,000
Money Market Investments [Member]
Amortized Cost	2,526,000	535,000
Gross Unrealized Gains
Gross Unrealized Losses
Fair Market Value	2,526,000	535,000
Mortgage-Backed Securities [Member]
Amortized Cost	3,057,000	3,458,000
Gross Unrealized Gains	36,000	64,000
Gross Unrealized Losses	22,000	8,000
Fair Market Value	3,071,000	3,514,000
Corporate Bonds And Direct Obligations Of Government Agencies [Member]
Amortized Cost	53,150,000	60,330,000
Gross Unrealized Gains	997,000	872,000
Gross Unrealized Losses	73,000	151,000
Fair Market Value	54,074,000	61,051,000
U.S. Treasury Obligations [Member]
Amortized Cost	10,506,000	12,584,000
Gross Unrealized Gains	52,000	6,000
Gross Unrealized Losses		23,000
Fair Market Value	$ 10,558,000	$ 12,567,000