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Concentration of Credit Risks - Narrative (Detail) - Two largest customers - Customer Concentration Risk
12 Months Ended
Dec. 26, 2020
Dec. 28, 2019
Sales    
Concentration Risk [Line Items]    
Concentration risk percentage 49.10% 46.30%
Accounts Receivable    
Concentration Risk [Line Items]    
Concentration risk percentage 45.10% 43.20%