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Summary of Significant Accounting Policies - Narrative (Details) - USD ($)
$ in Thousands
9 Months Ended
Sep. 27, 2019
Dec. 28, 2018
Disaggregation of Revenue [Line Items]    
Deferred revenues $ 1,030 $ 1,496
Refund liability 306 303
Right to recover product $ 189 $ 191
Maximum amortization period, capitalized contract costs 1 year  
Minimum    
Disaggregation of Revenue [Line Items]    
Payment term for contracts with customers 20 days  
Maximum    
Disaggregation of Revenue [Line Items]    
Payment term for contracts with customers 60 days