Summary of Significant Accounting Policies - Accounts Receivable Factoring (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 02, 2021	Jun. 26, 2020	Jul. 02, 2021	Jun. 26, 2020
Accounts Notes And Loans Receivable [Line Items]
Cost of services	$ 71,785	$ 70,408	$ 148,147	$ 140,311
Trade Accounts Receivable [Member] | Maximum [Member]
Accounts Notes And Loans Receivable [Line Items]
Cost of services	100	100	100	100
Trade Accounts Receivable [Member] | Factoring Agreement [Member]
Accounts Notes And Loans Receivable [Line Items]
Accounts Receivable, Sold	$ 10,100	$ 13,500	$ 25,600	$ 25,400