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Balance Sheet Components (Schedule of Available-for-Sale Short-Term Investments) (Details) - USD ($)
$ in Thousands
Jun. 28, 2020
Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]    
Cost $ 1,473 $ 1,475
Unrealized Gains 0 0
Unrealized Losses 0 0
Allowance for Credit Losses 0  
Estimated Fair Value 1,473 1,475
Certificates of deposit    
Debt Securities, Available-for-sale [Line Items]    
Cost 147 149
Unrealized Gains 0 0
Unrealized Losses 0 0
Allowance for Credit Losses 0  
Estimated Fair Value 147 149
Convertible debt    
Debt Securities, Available-for-sale [Line Items]    
Cost 1,326 1,326
Unrealized Gains 0 0
Unrealized Losses 0 0
Allowance for Credit Losses 0  
Estimated Fair Value $ 1,326 $ 1,326