Fair Value Measures (Schedule Of Assets And Liabilities Measured At Fair Value) (Details) - Fair Value, Measurements, Recurring [Member] - USD ($) $ in Thousands	Sep. 29, 2018	Dec. 30, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign currency contracts included in other current liabilities	$ (93)	$ (139)
Total financial assets and liabilities	128,325	105,951
Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets and liabilities	128,418	106,090
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign currency contracts included in other current liabilities	(93)	(139)
Total financial assets and liabilities	(93)	(139)
Money Market Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	128,418	106,090
Money Market Funds [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	$ 128,418	$ 106,090