Benefit Plans - Benefit Plan Expenses (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 28, 2020	Mar. 30, 2019
Retirement Benefits [Abstract]
Service cost	$ 618	$ 500
Interest cost	658	784
Expected return on plan assets	(727)	(790)
Amortization of prior service and net actuarial loss	145	62
Net periodic benefit cost	$ 694	$ 556