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Basis of Presentation and Significant Accounting Policies (Concentration Risk) (Details) - USD ($)
$ in Millions
3 Months Ended 9 Months Ended 12 Months Ended
Sep. 29, 2018
Sep. 30, 2017
Sep. 29, 2018
Sep. 30, 2017
Dec. 30, 2017
Risks and Uncertainties [Abstract]          
Revenue recognized on shipments to distributors $ 1.3   $ 13.7    
Allowance for doubtful accounts 0.4   $ 0.4   $ 9.4
Allowance for doubtful accounts, write-offs $ 9.0        
Revenue | Sell-Through Distributors Concentration Risk          
Risks and Uncertainties [Abstract]          
Concentration Risk 82.00% 80.00% 85.00% 75.00%  
Top Five Customers | Revenue | Customer Concentration Risk          
Risks and Uncertainties [Abstract]          
Concentration Risk 20.00% 23.00% 17.00% 28.00%  
Largest Customer | Revenue | Customer Concentration Risk          
Risks and Uncertainties [Abstract]          
Concentration Risk 6.00% 5.00% 5.00% 9.00%  
Largest Distributor Group | Trade receivables | Sell-Through Distributors Concentration Risk          
Risks and Uncertainties [Abstract]          
Concentration Risk     46.00%   66.00%
Second Largest Distributor Group | Trade receivables | Sell-Through Distributors Concentration Risk          
Risks and Uncertainties [Abstract]          
Concentration Risk     31.00%   0.00%