XML 50 R39.htm IDEA: XBRL DOCUMENT v3.20.2
Marketable Securities - Additional Information (Details) - USD ($)
6 Months Ended
Jun. 27, 2020
Dec. 28, 2019
Schedule Of Available For Sale Securities [Line Items]    
Accrued interest written off $ 0  
Percentage of available-for-sale securities in unrealized loss positions 19.00%  
Allowance for credit losses on securities in an unrealized loss position $ 0 $ 0
Allowance for credit loss 0  
Prepaid Expenses and Other Current Assets [Member]    
Schedule Of Available For Sale Securities [Line Items]    
Accrued interest receivable $ 9,506,000