Lease Commitments - Balance Sheet, Operating Lease Term and Discount Rate (Details) - USD ($) $ in Thousands	Dec. 26, 2020	Dec. 28, 2019
Assets
Operating ROU assets	$ 17,615	$ 21,918
Liabilities
Current operating lease liabilities	$ 6,811	$ 7,259
Operating Lease, Liability, Current, Statement of Financial Position	us-gaap:AccruedLiabilitiesCurrent	us-gaap:AccruedLiabilitiesCurrent
Non-current operating lease liabilities	$ 12,950	$ 17,166
Total lease liabilities	$ 19,761	$ 24,425
Weighted-average remaining lease term (years)	3 years 4 months 28 days	4 years 18 days
Weighted-average discount rate	5.06%	5.11%