Benefit Plans (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 25, 2021	Sep. 26, 2020	Sep. 25, 2021	Sep. 26, 2020
Pension Benefits
Components of net periodic benefit cost (income) [Abstract]
Interest cost	$ 313	$ 862	$ 939	$ 2,586
Expected return on plan assets	(903)	(1,496)	(2,711)	(4,486)
Amortization of net loss (gain)	378	494	1,135	1,482
Net periodic benefit income	(212)	(140)	(637)	(418)
Other Benefits
Components of net periodic benefit cost (income) [Abstract]
Interest cost	87	106	261	321
Amortization of net loss (gain)	(32)	(50)	(96)	(150)
Service cost	64	59	194	176
Amortization of prior service credit	(118)	(117)	(353)	(401)
Curtailment gain	0	0	0	(2,591)
Net periodic benefit income	$ 1	$ (2)	$ 6	$ (2,645)