Pension Benefits - Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income (Details) - Pension Plan - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 26, 2021
Pension Benefits
Net actuarial loss/(gain)	$ 19,100	$ (22,500)	$ (25,585)
Amortization of loss	(6,192)	(19,637)	(27,500)
Amortization of prior service credit	1,895	1,897	1,890
Total recognized in other comprehensive income	14,803	(40,240)	(51,195)
Net periodic pension (credit)/cost	(439)	14,634	18,805
Total recognized in net periodic pension benefit cost and other comprehensive income	14,364	(25,606)	(32,390)
Defined contribution plan, cost recognized	$ 39,000	$ 29,000	$ 33,000