Marketable Securities (Schedule Of Maturities of Marketable Securities) (Details) - USD ($) $ in Thousands	Jul. 01, 2017	Dec. 31, 2016
Marketable Securities [Abstract]
Amortized Cost, Due within one year	$ 6,154
Fair Value, Due within one year	6,213
Amortized Cost, Due after one year through five years	25,830
Fair Value, Due after one year through five years	26,176
Amortized Cost, Due after five years through ten years	21,904
Fair Value, Due after five years through ten years	22,438
Amortized Cost, Equity securities	1,198
Fair Value, Equity securities	8,232
Amortized Cost	55,086	$ 58,937
Available-for-sale Securities, Fair Value, Total	$ 63,059	$ 67,171