Cash, Cash Equivalents And Marketable Securities (Narrative) (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 29, 2013	Sep. 30, 2012	Sep. 29, 2013	Sep. 30, 2012
Transfers into Level 2	$ 0		$ 0
Transfers out of Level 2	0		0
Proceeds from sales of available-for-sale securities	723,000	14,211,000	17,373,000	24,466,000
Gross gains or losses related to sales of marketable securities	0	0	0	0
Net unrealized losses included in accumulated other comprehensive income, before taxes	12,000	2,000	42,000	24,000
Contractual maturities of marketable securities within 1 year	13,679,000		13,679,000
Contractual maturities of marketable securities, years 2-5	12,740,000		12,740,000
Contractual maturities of marketable securities, years 6-10	5,263,000		5,263,000
Contractual maturities of marketable securities, after 10 years	12,639,000		12,639,000
Marketable securities liquidation period			7 days
Accumulated Net Unrealized Investment Gain (Loss) [Member]
Reclassification out of AOCI	$ 0	$ 0	$ 0	$ 0