Cash, Cash Equivalents And Marketable Securities (Summary Of The Amortized Costs And Fair Values Of Marketable Securities) (Details) - USD ($) $ in Thousands	Jul. 03, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
MARKETABLE SECURITIES, Amortized Cost	$ 56,269	$ 32,273
MARKETABLE SECURITIES, Fair Value	56,282	32,259
MARKETABLE SECURITIES, Gross Unrealized Gains	19	4
MARKETABLE SECURITIES, Gross Unrealized Losses	6	18
Tax-Exempt Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
MARKETABLE SECURITIES, Amortized Cost	31,177	20,129
MARKETABLE SECURITIES, Fair Value	31,190	20,115
MARKETABLE SECURITIES, Gross Unrealized Gains	19	4
MARKETABLE SECURITIES, Gross Unrealized Losses	6	18
Variable Rate Demand Notes [Member]
Schedule of Available-for-sale Securities [Line Items]
MARKETABLE SECURITIES, Amortized Cost	25,092	12,144
MARKETABLE SECURITIES, Fair Value	$ 25,092	$ 12,144