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Employee Benefit Plans - (Assumptions) (Details)
12 Months Ended
Dec. 30, 2020
Dec. 25, 2019
Dec. 26, 2018
Retirement Benefits [Abstract]      
Discount rate used to determine the benefit obligations 1.34% 2.56%  
Discount rate used to determine net period pension costs 2.56% 3.83% 3.08%