General - Defined Benefit Plan (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 24, 2020	Sep. 26, 2019	Sep. 24, 2020	Sep. 26, 2019
General
Service cost	$ 274	$ 207	$ 821	$ 625
Interest cost	342	372	1,028	1,114
Net amortization of prior service cost and actuarial loss	248	109	743	327
Net periodic pension cost	$ 864	$ 688	$ 2,592	$ 2,066

Amount of cost recognized for passage of time related to defined benefit plan.

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Name:	us-gaap_DefinedBenefitPlanInterestCost
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration