Cash, Cash Equivalents And Marketable Securities (Narrative) (Details) (USD $)	3 Months Ended		6 Months Ended
	Jul. 01, 2012	Jul. 03, 2011	Jul. 01, 2012	Jul. 03, 2011
Cash, Cash Equivalents And Marketable Securities [Abstract]
Proceeds from sales of available-for-sale securities	$ 3,883,000	$ 9,462,000	$ 10,255,000	$ 45,347,000
Net unrealized losses included in accumulated other comprehensive income, before taxes	(27,000)	18,000	(22,000)	(1,000)
Contractual maturities of investments marketable securities, within one year	6,803,000		6,803,000
Contractual maturities of investments marketable securities, beyond one year to five years	27,289,000		27,289,000
Contractual maturities of investments marketable securities, beyond five years to ten years	9,141,000		9,141,000
Contractual maturities of investments marketable securities, beyond ten years	$ 20,838,000		$ 20,838,000