Summary of Significant Accounting Policies - Supplemental Cash Flow Items (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 27, 2020	Jun. 29, 2019
Supplemental Disclosures of Cash Flow Information
Interest paid	$ 6,114	$ 7,985
Taxes paid	495	3,389
Non-cash activities:
Purchases of property and equipment not paid	$ 1,914	$ 3,671