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Organization And Summary Of Significant Accounting Policies - Narrative (Details) - segments
9 Months Ended 12 Months Ended
Sep. 30, 2018
Oct. 02, 2016
Dec. 30, 2018
Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]        
Number of business segments 3 3    
Concentration Risk [Line Items]        
Credit Agricole loan borrowing capacity     95.0  
Operating lease, term     25 years  
Customer One | Costs and Estimated Earnings in Excess of Billings | Customer Concentration Risk        
Concentration Risk [Line Items]        
Concentration risk, percentage     24.00% 22.00%
Leased Solar Power Systems        
Concentration Risk [Line Items]        
Operating lease, term     20 years  
Solar Panel        
Concentration Risk [Line Items]        
Warranty, term     25 years  
Minimum | Certain System Components        
Concentration Risk [Line Items]        
Warranty, term     5 years  
Maximum | Certain System Components        
Concentration Risk [Line Items]        
Warranty, term     20 years