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, 2023	Dec. 31, 2022	Dec. 26, 2021
Other Postretirement Benefits
Net actuarial (gain)/loss	$ (6,916)	$ (6,801)	$ 2,254
Amortization of loss	(1,945)	(3,293)	(3,407)
Amortization of prior service credit	0	368	3,098
Total recognized in other comprehensive income	(8,861)	(9,726)	1,945
Net periodic postretirement benefit cost	3,478	3,702	927
Total recognized in net periodic postretirement benefit cost and other comprehensive (income)/loss	$ (5,383)	$ (6,024)	$ 2,872