Marketable Securities - Available-for-sale Securities - Continuous Loss Position (Details) - USD ($) $ in Thousands	Sep. 26, 2021	Dec. 27, 2020
Total short-term AFS securities
Short-term AFS securities
Fair value, less than 12 months	$ 60,701	$ 58,867
Gross unrealized losses, less than 12 months	(16)	(13)
Fair value, greater than 12 months	0	8,749
Gross unrealized losses, greater than 12 months	0	(1)
Fair value, total	60,701	67,616
Gross unrealized losses, total	(16)	(14)
Total long-term AFS securities
Long-term AFS securities
Fair value, less than 12 months	230,422	37,937
Gross unrealized losses, less than 12 months	(391)	(28)
Fair value, greater than 12 months	0	0
Gross unrealized losses, greater than 12 months	0	0
Fair value, total	230,422	37,937
Gross unrealized losses, total	(391)	(28)
U.S. Treasury securities
Short-term AFS securities
Fair value, less than 12 months	32,611	20,133
Gross unrealized losses, less than 12 months	(2)	(3)
Fair value, greater than 12 months	0	0
Gross unrealized losses, greater than 12 months	0	0
Fair value, total	32,611	20,133
Gross unrealized losses, total	(2)	(3)
Long-term AFS securities
Fair value, less than 12 months	54,539
Gross unrealized losses, less than 12 months	(61)
Fair value, greater than 12 months	0
Gross unrealized losses, greater than 12 months	0
Fair value, total	54,539
Gross unrealized losses, total	(61)
Corporate debt securities
Short-term AFS securities
Fair value, less than 12 months	28,090	33,735
Gross unrealized losses, less than 12 months	(14)	(8)
Fair value, greater than 12 months	0	0
Gross unrealized losses, greater than 12 months	0	0
Fair value, total	28,090	33,735
Gross unrealized losses, total	(14)	(8)
Long-term AFS securities
Fair value, less than 12 months	128,315	6,717
Gross unrealized losses, less than 12 months	(274)	(5)
Fair value, greater than 12 months	0	0
Gross unrealized losses, greater than 12 months	0	0
Fair value, total	128,315	6,717
Gross unrealized losses, total	(274)	(5)
U.S. governmental agency securities
Short-term AFS securities
Fair value, less than 12 months		4,999
Gross unrealized losses, less than 12 months		(2)
Fair value, greater than 12 months		8,749
Gross unrealized losses, greater than 12 months		(1)
Fair value, total		13,748
Gross unrealized losses, total		(3)
Long-term AFS securities
Fair value, less than 12 months	42,454	26,236
Gross unrealized losses, less than 12 months	(43)	(13)
Fair value, greater than 12 months	0	0
Gross unrealized losses, greater than 12 months	0	0
Fair value, total	42,454	26,236
Gross unrealized losses, total	(43)	(13)
Municipal securities
Long-term AFS securities
Fair value, less than 12 months	5,114	4,984
Gross unrealized losses, less than 12 months	(13)	(10)
Fair value, greater than 12 months	0	0
Gross unrealized losses, greater than 12 months	0	0
Fair value, total	5,114	4,984
Gross unrealized losses, total	$ (13)	$ (10)