Cash, Cash Equivalents And Marketable Securities (Narrative) (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 28, 2014	Sep. 29, 2013	Sep. 28, 2014	Sep. 29, 2013
Cash, Cash Equivalents And Marketable Securities [Line Items]
Transfers into Level 2	$ 0		$ 0
Transfers out of Level 2	0		0
Proceeds from sales of available-for-sale securities	4,225,000	723,000	18,613,000	17,373,000
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	(5,000)	(12,000)	1,000	(42,000)
Contractual maturities of marketable securities within 1 year	4,354,000		4,354,000
Contractual maturities of marketable securities, years 2-5	3,177,000		3,177,000
Contractual maturities of marketable securities, years 6-10	6,448,000		6,448,000
Contractual maturities of marketable securities, after 10 years	6,646,000		6,646,000
Marketable securities liquidation period			7 days
Accumulated Net Unrealized Investment Gain (Loss) [Member]
Cash, Cash Equivalents And Marketable Securities [Line Items]
Reclassification out of AOCI	$ 0	$ 0	$ 0	$ 0