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Cash and Investments - Narrative (Details)
3 Months Ended
Apr. 03, 2020
USD ($)
investment
Mar. 29, 2019
USD ($)
Jan. 03, 2020
USD ($)
investment
Investments, Debt and Equity Securities [Abstract]      
Interest receivable $ 5,400,000   $ 6,200,000
Gain (loss) on sales of investments available-for-sale $ 0 $ 0  
Number of investments in an unrealized loss position | investment 144   9
Allowance for credit losses $ 0 $ 0