Summary Of Significant Accounting Policies (Schedule Of Assets And Liabilities Measured At Fair Value) (Details) - Fair Value, Measurements, Recurring [Member] - USD ($) $ in Thousands	Dec. 28, 2019	Dec. 29, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds included in cash equivalents	$ 180,032	$ 129,449
Foreign currency contracts included in other current liabilities	(764)	(309)
Total financial assets and liabilities	179,268	129,140
Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds included in cash equivalents	180,032	129,449
Total financial assets and liabilities	180,032	129,449
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	(764)	(309)
Total financial assets and liabilities	$ (764)	$ (309)