Employee Benefit Plans - Components Of Net Periodic Benefit Costs (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 26, 2022	Jun. 30, 2023	Jun. 26, 2022
Pension and SERPA Benefits:
Defined Benefit Plan Disclosure
Service cost	$ 1,294	$ 4,763	$ 2,588	$ 9,525
Interest cost	20,476	15,472	40,952	30,945
Expected return on plan assets	(36,519)	(31,476)	(73,038)	(62,952)
Amortization of unrecognized: Prior service cost (credit)	188	(328)	376	(656)
Amortization of unrecognized: Net (gain) loss	(181)	7,978	(362)	15,956
Settlement gain	0	0	(222)	(256)
Net periodic benefit income	(14,742)	(3,591)	(29,706)	(7,438)
Postretirement Healthcare Benefits:
Defined Benefit Plan Disclosure
Service cost	797	1,161	1,594	2,322
Interest cost	2,772	1,904	5,544	3,808
Expected return on plan assets	(4,281)	(3,809)	(8,562)	(7,618)
Amortization of unrecognized: Prior service cost (credit)	(166)	(581)	(332)	(1,162)
Amortization of unrecognized: Net (gain) loss	(1,097)	122	(2,194)	244
Net periodic benefit income	$ (1,975)	$ (1,203)	$ (3,950)	$ (2,406)