Employee Benefit Plans - Components Of Net Periodic Benefit Costs (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 25, 2022	Sep. 26, 2021	Sep. 25, 2022	Sep. 26, 2021
Pension and SERPA Benefits:
Defined Benefit Plan Disclosure
Service cost	$ 4,763	$ 6,348	$ 14,289	$ 19,044
Interest cost	15,473	15,472	46,418	46,412
Expected return on plan assets	(31,476)	(32,720)	(94,428)	(98,160)
Amortization of unrecognized: Prior service credit	(328)	(312)	(984)	(936)
Amortization of unrecognized: Net loss	7,978	18,386	23,934	55,158
Settlement (gain) loss	0	0	(256)	816
Net periodic benefit (income) cost	(3,590)	7,174	(11,027)	22,334
Postretirement Healthcare Benefits:
Defined Benefit Plan Disclosure
Service cost	1,161	1,288	3,482	3,864
Interest cost	1,904	1,626	5,712	4,878
Expected return on plan assets	(3,809)	(3,495)	(11,427)	(10,485)
Amortization of unrecognized: Prior service credit	(581)	(581)	(1,743)	(1,743)
Amortization of unrecognized: Net loss	122	264	366	792
Net periodic benefit (income) cost	$ (1,203)	$ (898)	$ (3,610)	$ (2,694)