Marketable Securities - Narrative (Details) - USD ($)	9 Months Ended	12 Months Ended
	Sep. 26, 2021	Dec. 27, 2020
Line of Credit Facility [Line Items]
Net unrealized gains in other comprehensive income	$ 1,700,000	$ 4,300,000
OTTI loss recognized	$ 0	$ 0
Short-term Marketable Securities | Minimum
Line of Credit Facility [Line Items]
Marketable securities, remaining maturities (in months)	1 month	1 month
Short-term Marketable Securities | Maximum
Line of Credit Facility [Line Items]
Marketable securities, remaining maturities (in months)	12 months	12 months
Long-term Marketable Securities | Minimum
Line of Credit Facility [Line Items]
Marketable securities, remaining maturities (in months)	13 months	13 months
Long-term Marketable Securities | Maximum
Line of Credit Facility [Line Items]
Marketable securities, remaining maturities (in months)	36 months	36 months