Fair Value Measures (Schedule Of Assets And Liabilities Measured At Fair Value) (Details) - Fair Value, Measurements, Recurring [Member] - USD ($) $ in Thousands |
Mar. 31, 2018 |
Dec. 30, 2017 |
|---|---|---|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ||
| Money market funds included in cash equivalents | $ 167,207 | $ 106,090 |
| Foreign currency contracts included in other current liabilities | (369) | (139) |
| Total financial assets and liabilities | 166,838 | 105,951 |
| 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 | 167,207 | 106,090 |
| Total financial assets and liabilities | 167,207 | 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 | (369) | (139) |
| Total financial assets and liabilities | $ (369) | $ (139) |