Marketable Securities - Continuous Loss Position (Details) - USD ($)	12 Months Ended
	Dec. 26, 2021	Dec. 27, 2020
Long-term AFS securities
Other than temporary impairment, loss	$ 0	$ 0
Minimum | Short-term Marketable Securities
Long-term AFS securities
Remaining maturities on short-term and long-term marketable securities	1 month
Minimum | Long-term Marketable Securities
Long-term AFS securities
Remaining maturities on short-term and long-term marketable securities	13 months
Maximum | Short-term Marketable Securities
Long-term AFS securities
Remaining maturities on short-term and long-term marketable securities	12 months
Maximum | Long-term Marketable Securities
Long-term AFS securities
Remaining maturities on short-term and long-term marketable securities	35 months
U.S. Treasury securities
Short-term AFS securities
Fair value, less than 12 months, short-term AFS securities	$ 61,018,000	20,133,000
Gross unrealized losses, less than 12 months, short-term AFS securities	(43,000)	(3,000)
Fair value, 12 months or greater, short-term AFS securities	0	0
Gross unrealized losses, 12 months or greater, short-term AFS securities	0	0
Fair value, short-term AFS securities	61,018,000	20,133,000
Gross unrealized losses, short-term AFS securities	(43,000)	(3,000)
Long-term AFS securities
Fair value, less than 12 months, long-term AFS securities	119,146,000
Gross unrealized losses, less than 12 months, long-term AFS securities	(549,000)
Fair value, 12 months or greater, long-term AFS securities	0
Gross unrealized losses, 12 months or greater, long-term AFS securities	0
Fair value, long-term AFS securities	119,146,000
Gross unrealized losses, long-term AFS securities	(549,000)
Corporate debt securities
Short-term AFS securities
Fair value, less than 12 months, short-term AFS securities	53,148,000	33,735,000
Gross unrealized losses, less than 12 months, short-term AFS securities	(69,000)	(8,000)
Fair value, 12 months or greater, short-term AFS securities	0	0
Gross unrealized losses, 12 months or greater, short-term AFS securities	0	0
Fair value, short-term AFS securities	53,148,000	33,735,000
Gross unrealized losses, short-term AFS securities	(69,000)	(8,000)
Long-term AFS securities
Fair value, less than 12 months, long-term AFS securities	224,022,000	6,717,000
Gross unrealized losses, less than 12 months, long-term AFS securities	(1,858,000)	(5,000)
Fair value, 12 months or greater, long-term AFS securities	0	0
Gross unrealized losses, 12 months or greater, long-term AFS securities	0	0
Fair value, long-term AFS securities	224,022,000	6,717,000
Gross unrealized losses, long-term AFS securities	(1,858,000)	(5,000)
Municipal securities
Short-term AFS securities
Fair value, less than 12 months, short-term AFS securities	1,998,000
Gross unrealized losses, less than 12 months, short-term AFS securities	(2,000)
Fair value, 12 months or greater, short-term AFS securities	0
Gross unrealized losses, 12 months or greater, short-term AFS securities	0
Fair value, short-term AFS securities	1,998,000
Gross unrealized losses, short-term AFS securities	(2,000)
Long-term AFS securities
Fair value, less than 12 months, long-term AFS securities	13,933,000	4,984,000
Gross unrealized losses, less than 12 months, long-term AFS securities	(61,000)	(10,000)
Fair value, 12 months or greater, long-term AFS securities	0	0
Gross unrealized losses, 12 months or greater, long-term AFS securities	0	0
Fair value, long-term AFS securities	13,933,000	4,984,000
Gross unrealized losses, long-term AFS securities	(61,000)	(10,000)
U.S. governmental agency securities
Short-term AFS securities
Fair value, less than 12 months, short-term AFS securities		4,999,000
Gross unrealized losses, less than 12 months, short-term AFS securities		(2,000)
Fair value, 12 months or greater, short-term AFS securities		8,749,000
Gross unrealized losses, 12 months or greater, short-term AFS securities		(1,000)
Fair value, short-term AFS securities		13,748,000
Gross unrealized losses, short-term AFS securities		(3,000)
Long-term AFS securities
Fair value, less than 12 months, long-term AFS securities	39,246,000	26,236,000
Gross unrealized losses, less than 12 months, long-term AFS securities	(252,000)	(13,000)
Fair value, 12 months or greater, long-term AFS securities	0	0
Gross unrealized losses, 12 months or greater, long-term AFS securities	0	0
Fair value, long-term AFS securities	39,246,000	26,236,000
Gross unrealized losses, long-term AFS securities	(252,000)	(13,000)
Total short-term AFS securities
Short-term AFS securities
Fair value, less than 12 months, short-term AFS securities	116,164,000	58,867,000
Gross unrealized losses, less than 12 months, short-term AFS securities	(114,000)	(13,000)
Fair value, 12 months or greater, short-term AFS securities	0	8,749,000
Gross unrealized losses, 12 months or greater, short-term AFS securities	0	(1,000)
Fair value, short-term AFS securities	116,164,000	67,616,000
Gross unrealized losses, short-term AFS securities	(114,000)	(14,000)
Total long-term AFS securities
Long-term AFS securities
Fair value, less than 12 months, long-term AFS securities	396,347,000	37,937,000
Gross unrealized losses, less than 12 months, long-term AFS securities	(2,720,000)	(28,000)
Fair value, 12 months or greater, long-term AFS securities	0	0
Gross unrealized losses, 12 months or greater, long-term AFS securities	0	0
Fair value, long-term AFS securities	396,347,000	37,937,000
Gross unrealized losses, long-term AFS securities	$ (2,720,000)	$ (28,000)