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Property and Equipment, Net (Narrative) (Details) - USD ($)
$ in Thousands
12 Months Ended
Dec. 27, 2019
Dec. 28, 2018
Dec. 29, 2017
Property Plant And Equipment [Abstract]      
Depreciation expense $ 3,206 $ 2,465 $ 2,442
Write off remaining investment $ 1,200 $ 5,900