Other Postretirement Benefits - Changes in the Benefit Obligations Recognized in Other Comprehensive Income (Details) - Other Postretirement Benefit Plans - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 26, 2021	Dec. 27, 2020
Other Postretirement Benefits
Net actuarial (gain)/loss	$ (6,801)	$ 2,254	$ 4,044
Amortization of loss	(3,293)	(3,407)	(3,051)
Amortization of prior service credit	368	3,098	4,225
Total recognized in other comprehensive (income)/loss	(9,726)	1,945	5,218
Net periodic postretirement benefit cost/(income)	3,702	927	(119)
Total recognized in net periodic postretirement benefit cost/(income) and other comprehensive (income)/loss	$ (6,024)	$ 2,872	$ 5,099