Pension and Other Postretirement Benefits - Pension Benefits - Net Periodic Pension Cost (Details) - Pension Plan - USD ($) $ in Thousands	3 Months Ended
	Mar. 27, 2022	Mar. 28, 2021
Pension Benefits
Service cost	$ 2,882	$ 2,276
Interest cost	10,121	8,717
Expected return on plan assets	(13,807)	(12,677)
Amortization of actuarial loss	4,909	6,876
Amortization of prior service credit	(486)	(486)
Net periodic postretirement benefit cost	3,619	4,706
Qualified Plans
Pension Benefits
Service cost	2,882	2,276
Interest cost	8,837	7,629
Expected return on plan assets	(13,807)	(12,677)
Amortization of actuarial loss	3,266	5,055
Amortization of prior service credit	(486)	(486)
Net periodic postretirement benefit cost	692	1,797
Pension contributions	2,300	1,500
Expected future employer contributions	10,000
Non- Qualified Plans
Pension Benefits
Service cost	0	0
Interest cost	1,284	1,088
Expected return on plan assets	0	0
Amortization of actuarial loss	1,643	1,821
Amortization of prior service credit	0	0
Net periodic postretirement benefit cost	$ 2,927	$ 2,909