Marketable Securities - Available-for-sale Securities - Continuous Loss Position (Details) - USD ($) $ in Thousands	Jun. 27, 2021	Dec. 27, 2020
Total short-term AFS securities
Short-term AFS securities
Fair value, less than 12 months	$ 50,703	$ 58,867
Gross unrealized losses, less than 12 months	(15)	(13)
Fair value, greater than 12 months	0	8,749
Gross unrealized losses, greater than 12 months	0	(1)
Fair value, total	50,703	67,616
Gross unrealized losses, total	(15)	(14)
Total long-term AFS securities
Long-term AFS securities
Fair value, less than 12 months	109,333	37,937
Gross unrealized losses, less than 12 months	(211)	(28)
Fair value, greater than 12 months	0	0
Gross unrealized losses, greater than 12 months	0	0
Fair value, total	109,333	37,937
Gross unrealized losses, total	(211)	(28)
Corporate debt securities
Short-term AFS securities
Fair value, less than 12 months	28,033	33,735
Gross unrealized losses, less than 12 months	(12)	(8)
Fair value, greater than 12 months	0	0
Gross unrealized losses, greater than 12 months	0	0
Fair value, total	28,033	33,735
Gross unrealized losses, total	(12)	(8)
Long-term AFS securities
Fair value, less than 12 months	50,552	6,717
Gross unrealized losses, less than 12 months	(123)	(5)
Fair value, greater than 12 months	0	0
Gross unrealized losses, greater than 12 months	0	0
Fair value, total	50,552	6,717
Gross unrealized losses, total	(123)	(5)
U.S. Treasury securities
Short-term AFS securities
Fair value, less than 12 months	22,670	20,133
Gross unrealized losses, less than 12 months	(3)	(3)
Fair value, greater than 12 months	0	0
Gross unrealized losses, greater than 12 months	0	0
Fair value, total	22,670	20,133
Gross unrealized losses, total	(3)	(3)
Long-term AFS securities
Fair value, less than 12 months	11,212
Gross unrealized losses, less than 12 months	(15)
Fair value, greater than 12 months	0
Gross unrealized losses, greater than 12 months	0
Fair value, total	11,212
Gross unrealized losses, total	(15)
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	42,428	26,236
Gross unrealized losses, less than 12 months	(67)	(13)
Fair value, greater than 12 months	0	0
Gross unrealized losses, greater than 12 months	0	0
Fair value, total	42,428	26,236
Gross unrealized losses, total	(67)	(13)
Municipal securities
Long-term AFS securities
Fair value, less than 12 months	5,141	4,984
Gross unrealized losses, less than 12 months	(6)	(10)
Fair value, greater than 12 months	0	0
Gross unrealized losses, greater than 12 months	0	0
Fair value, total	5,141	4,984
Gross unrealized losses, total	$ (6)	$ (10)