Other Postretirement Benefits - Narrative (Details) - Other Postretirement Benefit Plans - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 26, 2021
Other Postretirement Benefits
Additional postretirement costs	$ 20,000	$ 19,000	$ 17,000
Benefit obligation	22,912	30,696	$ 40,607
Actuarial gain	6,916	6,801
Employer contributions	2,401	3,887
Postemployment benefits liability	$ 7,800	$ 7,900