Marketable Securities (Maturities of Marketable Securities) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 27, 2014	Dec. 28, 2013
Marketable Securities [Abstract]
Amortized Cost, Due within one year	$ 4,940
Fair Value, Due within one year	4,970
Amortized Cost, Due after one year through five years	41,637
Fair Value, Due after one year through five years	43,005
Amortized Cost, Due after five years through ten years	12,192
Fair Value, Due after five years through ten years	12,510
Amortized Cost, Due after ten years	600
Fair Value, Due after ten years	600
Amortized Cost, Equity securities	1,198
Fair Value, Equity securities	8,133
Amortized Cost, Total	60,567	56,401
Available-for-sale Securities, Fair Value, Total	$ 69,218	$ 63,093