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Basis of Presentation and General Information (Narrative) (Details) - USD ($)
3 Months Ended
Mar. 27, 2020
Mar. 29, 2019
Dec. 27, 2019
Dec. 28, 2018
Basis Of Presentation And General Information [Line Items]        
Revenue recognized as a result of change in contract liability $ 4,400,000 $ 4,000,000    
Deferred commissions     $ 1,600,000 $ 1,200,000
Commissions expense 400,000 200,000    
Impairment loss recognized to capitalization of deferred commission $ 0 $ 0    
Minimum [Member]        
Basis Of Presentation And General Information [Line Items]        
Business relationship agreement period 6 months      
Maximum [Member]        
Basis Of Presentation And General Information [Line Items]        
Business relationship agreement period 12 months      
Customer contract period 12 months