Employee Benefit Plans - Components of Net Periodic Benefit Costs (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 25, 2022	Sep. 30, 2023	Sep. 25, 2022
Pension and SERPA Benefits:
Defined Benefit Plan Disclosure
Service cost	$ 1,294	$ 4,763	$ 3,882	$ 14,289
Interest cost	20,476	15,473	61,429	46,418
Expected return on plan assets	(36,519)	(31,476)	(109,557)	(94,428)
Amortization of unrecognized: Prior service cost (credit)	188	(328)	564	(984)
Amortization of unrecognized: Net (gain) loss	(181)	7,978	(543)	23,934
Settlement gain	0	0	(222)	(256)
Net periodic benefit income	(14,742)	(3,590)	(44,447)	(11,027)
Postretirement Healthcare Benefits:
Defined Benefit Plan Disclosure
Service cost	797	1,161	2,390	3,482
Interest cost	2,772	1,904	8,316	5,712
Expected return on plan assets	(4,281)	(3,809)	(12,843)	(11,427)
Amortization of unrecognized: Prior service cost (credit)	(166)	(581)	(498)	(1,743)
Amortization of unrecognized: Net (gain) loss	(1,097)	122	(3,291)	366
Net periodic benefit income	$ (1,975)	$ (1,203)	$ (5,926)	$ (3,610)