Significant Accounting Policies - Adoption of New Revenue Accounting Standard (Details) - USD ($) $ in Thousands	Dec. 30, 2018	Jun. 29, 2019	Dec. 29, 2018
Adoption of New Accounting Standard
Operating lease right-of-use assets, Statement of Financial Position		us-gaap:OtherAssetsNoncurrent
Operating lease liabilities, Statement of Financial Position		us-gaap:OtherLiabilitiesCurrent us-gaap:LiabilitiesOtherThanLongtermDebtNoncurrent
Balance Sheet effect
Prepaid expenses and other current assets		$ 59,662	$ 64,650
Other current liabilities		$ 68,186	$ 81,180
ASU 2016-02 - Leases
Adoption of New Accounting Standard
Election of practical expedients package, leases	true
ASU 2016-02 - Leases | Cumulative effect adjustment
Balance Sheet effect
Prepaid expenses and other current assets	$ (481)
Other assets, net	18,166
Other current liabilities	3,516
Other non-current liabilities	$ 14,169