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Summary of Significant Accounting Policies - Useful Life (Details)
12 Months Ended
Dec. 28, 2019
Buildings  
Property, Plant and Equipment [Line Items]  
Property and equipment, useful life 39 years
Demonstration units  
Property, Plant and Equipment [Line Items]  
Property and equipment, useful life 3 years
Tooling  
Property, Plant and Equipment [Line Items]  
Property and equipment, useful life 3 years
Vehicles  
Property, Plant and Equipment [Line Items]  
Property and equipment, useful life 5 years