Benefit Plans - Benefit Plan Expenses (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 27, 2021	Mar. 28, 2020
Retirement Benefits [Abstract]
Service cost	$ 702	$ 618
Interest cost	440	658
Expected return on plan assets	(367)	(727)
Amortization of prior service and net actuarial loss	331	145
Net periodic benefit cost	$ 1,106	$ 694