Lease Commitments - Lease Cost (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 26, 2020	Dec. 28, 2019
Leases [Abstract]
Short-term lease expenses	$ 512	$ 562
Variable lease expenses	1,307	916
Operating lease rent expenses	8,591	8,664
Total operating lease costs	$ 10,410	$ 10,142