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Summary of Significant Accounting Policies - Allowance for Doubtful Accounts (Details) - USD ($)
$ in Thousands
12 Months Ended
Dec. 26, 2020
Dec. 28, 2019
Dec. 29, 2018
Allowance for Doubtful Accounts Receivable [Roll Forward]      
Balance at beginning of year $ 222 $ 185 $ 200
Charges (reversals) to costs and expenses 26 37 (15)
Balance at end of year $ 248 $ 222 $ 185