Fair Value of Financial Instruments (Details) (USD $) In Thousands, unless otherwise specified	Sep. 27, 2014	Dec. 28, 2013
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value of marketable securities	$ 134,131	$ 106,746
Total
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Foreign currency forward exchange contracts	150	48
Total fair value of financial instruments	134,281	106,794
Short-term marketable securities | Total
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value of marketable securities	134,131	101,505
Long-term marketable securities | Total
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value of marketable securities	0	5,241
Level 1
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Total fair value of financial instruments	134,131	101,505
Level 1 | Short-term marketable securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value of marketable securities	134,131	101,505
Level 2
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Foreign currency forward exchange contracts	150	48
Total fair value of financial instruments	150	48
Level 3
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Total fair value of financial instruments	0	5,241
Level 3 | Long-term marketable securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value of marketable securities	$ 0	$ 5,241