Retirement Benefits (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 01, 2022	Jun. 25, 2021	Jul. 01, 2022	Jun. 25, 2021
Pension
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 1,964	$ 2,724	$ 4,134	$ 5,445
Interest cost	2,766	2,976	5,504	5,957
Expected return on assets	(4,777)	(5,131)	(9,579)	(10,261)
Amortization and other	1,419	2,555	2,495	5,106
Net periodic benefit cost	1,372	3,124	2,554	6,247
Postretirement Medical
Defined Benefit Plan Disclosure [Line Items]
Service cost	83	175	258	350
Interest cost	195	250	420	500
Amortization	(2)	250	173	500
Net periodic benefit cost	$ 276	$ 675	$ 851	$ 1,350