Employee Benefit Plans (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 26, 2020 USD ($) plan	Sep. 28, 2019 USD ($)	Sep. 26, 2020 USD ($) plan	Sep. 28, 2019 USD ($)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Amount Company expects to contribute to its pension plans	$ 4,900		$ 4,900
Payment for pension benefits			$ 10,300	$ 2,700
Defined Benefit Plan, Additional Information [Abstract]
Number Of Multiemployer Plans, Withdrawal Obligation Could Be Material | plan	2		2
Number Of Multiemployer Plans Withdrawal Obligation Could Be Material Certified Red Zone | plan	1		1
Number of Multiemployer Plans, Certified Red Zone | plan	5		5
Number of Multiemployer Plans, Certified Yellow Zone | plan	2		2
Number Of Multiemployer Plans, Withdrawal Obligation | plan	5		5
Accrued liability representing the present value of scheduled withdrawal liability payments for under-funded multi-employer plan	$ 2,700		$ 2,700
Multiemployer Plans, Withdrawal Obligation, Settlement	2,500
Maximum [Member]
Defined Benefit Plan, Additional Information [Abstract]
Multiemployer Plan, Contributions To Individual Plan, Percent			5.00%
Pension Plan, Defined Benefit [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	764	$ 664	$ 2,268	2,025
Interest cost	1,425	1,698	4,283	5,122
Expected return on plan assets	(2,042)	(1,816)	(6,113)	(5,452)
Amortization of prior service cost	9	9	25	27
Amortization of net loss	854	1,146	2,562	3,439
Net pension cost	$ 1,010	$ 1,701	$ 3,025	$ 5,161