Pensions and Other Post-employment Benefits (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 27, 2025	Jun. 28, 2024	Jun. 27, 2025	Jun. 28, 2024
Components of net periodic benefit (credit) cost
Contributions by employer	$ 0	$ 0	$ 0	$ 0
Pension Benefits
Components of net periodic benefit (credit) cost
Service cost	308,000	266,000	594,000	534,000
Interest cost	1,927,000	1,905,000	3,837,000	3,812,000
Expected return on plan assets	(2,532,000)	(2,529,000)	(5,036,000)	(5,059,000)
Amortization of prior service (benefit) cost	(23,000)	(21,000)	(44,000)	(42,000)
Amortization of net loss (gain)	90,000	32,000	179,000	64,000
Net periodic benefit (credit) cost	(230,000)	(347,000)	(470,000)	(691,000)
Other Benefits
Components of net periodic benefit (credit) cost
Service cost	11,000	12,000	22,000	25,000
Interest cost	58,000	58,000	116,000	117,000
Expected return on plan assets	0	0	0	0
Amortization of prior service (benefit) cost	0	0	0	0
Amortization of net loss (gain)	(88,000)	(87,000)	(175,000)	(174,000)
Net periodic benefit (credit) cost	$ (19,000)	$ (17,000)	$ (37,000)	$ (32,000)