Employee Benefit Plans - Net periodic pension cost (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 30, 2021	Dec. 31, 2020	Dec. 26, 2019
Net periodic pension cost:
Service cost	$ 1,122	$ 1,095	$ 833
Interest cost	1,201	1,371	1,485
Net amortization of prior service cost and actuarial loss	1,311	990	436
Total	$ 3,634	$ 3,456	$ 2,754