Marketable Securities - Available-for-sale Securities - Continuous Loss Position (Details) - USD ($) $ in Thousands	Mar. 29, 2020	Dec. 29, 2019
Total short-term AFS securities
Short-term AFS securities
Fair value, less than 12 months	$ 81,997	$ 34,271
Gross unrealized losses, less than 12 months	(571)	(9)
Fair value, greater than 12 months	9,501	34,398
Gross unrealized losses, greater than 12 months	(2)	(15)
Fair value, total	91,498	68,669
Gross unrealized losses, total	(573)	(24)
Total long-term AFS securities
Long-term AFS securities
Fair value, less than 12 months	85,058	130,993
Gross unrealized losses, less than 12 months	(1,743)	(212)
Fair value, greater than 12 months	0	4,502
Gross unrealized losses, greater than 12 months	0	(4)
Fair value, total	85,058	135,495
Gross unrealized losses, total	(1,743)	(216)
US Treasury Securities
Short-term AFS securities
Fair value, less than 12 months	0	13,296
Gross unrealized losses, less than 12 months	0	(3)
Fair value, greater than 12 months	9,501	11,147
Gross unrealized losses, greater than 12 months	(2)	(8)
Fair value, total	9,501	24,443
Gross unrealized losses, total	(2)	(11)
Long-term AFS securities
Fair value, less than 12 months		60,935
Gross unrealized losses, less than 12 months		(103)
Fair value, greater than 12 months		0
Gross unrealized losses, greater than 12 months		0
Fair value, total		60,935
Gross unrealized losses, total		(103)
Corporate debt securities
Short-term AFS securities
Fair value, less than 12 months	76,998	20,975
Gross unrealized losses, less than 12 months	(570)	(6)
Fair value, greater than 12 months	0	8,251
Gross unrealized losses, greater than 12 months	0	(3)
Fair value, total	76,998	29,226
Gross unrealized losses, total	(570)	(9)
Long-term AFS securities
Fair value, less than 12 months	76,311	35,891
Gross unrealized losses, less than 12 months	(1,740)	(25)
Fair value, greater than 12 months	0	4,502
Gross unrealized losses, greater than 12 months	0	(4)
Fair value, total	76,311	40,393
Gross unrealized losses, total	(1,740)	(29)
U.S. governmental agency securities
Short-term AFS securities
Fair value, less than 12 months	4,999	0
Gross unrealized losses, less than 12 months	(1)	0
Fair value, greater than 12 months	0	15,000
Gross unrealized losses, greater than 12 months	0	(4)
Fair value, total	4,999	15,000
Gross unrealized losses, total	(1)	(4)
Long-term AFS securities
Fair value, less than 12 months	8,747	34,167
Gross unrealized losses, less than 12 months	(3)	(84)
Fair value, greater than 12 months	0	0
Gross unrealized losses, greater than 12 months	0	0
Fair value, total	8,747	34,167
Gross unrealized losses, total	$ (3)	$ (84)