Debt - Schedule of debt (Details) - USD ($) $ in Thousands	Sep. 26, 2021	Dec. 31, 2020
Line of Credit Facility [Line Items]
Long-term Debt, Gross	$ 575,922	$ 674,986
Other	4,320	4,701
Less unamortized debt issuance costs	(12,600)	(16,684)
Less current portion of long-term debt	(5,528)	(5,528)
Long Term Debt Including Related Parties Noncurrent	570,394	669,458
First Lien Note [Member]
Line of Credit Facility [Line Items]
Long-term Debt, Gross	539,202	541,969
Second Lien Note [Member]
Line of Credit Facility [Line Items]
Long-term Debt, Gross	$ 45,000	$ 145,000