Fair Value of Financial Instruments - Contractual maturities of investments (Details) - USD ($) $ in Thousands	Jul. 03, 2021	Apr. 03, 2021	Jan. 02, 2021
Cost
Due in one year or less, Cost	$ 324,890
Due after one year through ten years, Cost	149,864
Due after ten years, Cost	6,300
Total Cost	481,054
Fair Value
Due in one year or less, Fair Value	325,468
Due after one year through ten years, Fair Value	150,001
Due after ten years, Fair Value	5,400
Total Fair Value	480,869
Continuous unrealized loss position, Fair Value
Fair value of available-for-sale securities, continuous loss position for less than twelve months		$ 68,396	$ 62,055
Fair value of available-for-sale securities, continuous loss position for twelve months or greater		5,100	5,340
Total fair value of available-for-sale securities, continuous loss position		73,496	67,395
Continuous unrealized loss position, Gross Unrealized Losses
Available-for-sale securities, continuous loss position for less than 12 months, gross unrealized losses		(94)	(79)
Available-for-sale securities, continuous loss position for 12 months or greater, gross unrealized losses		(900)	(660)
Available-for-sale securities, total gross unrealized losses		$ (994)	(739)
Government debt securities
Continuous unrealized loss position, Fair Value
Fair value of available-for-sale securities, continuous loss position for less than twelve months	21,082		10,146
Total fair value of available-for-sale securities, continuous loss position	21,082		10,146
Continuous unrealized loss position, Gross Unrealized Losses
Available-for-sale securities, continuous loss position for less than 12 months, gross unrealized losses	(26)		(5)
Available-for-sale securities, total gross unrealized losses	(26)		(5)
Corporate debt securities
Continuous unrealized loss position, Fair Value
Fair value of available-for-sale securities, continuous loss position for less than twelve months	47,314		51,909
Total fair value of available-for-sale securities, continuous loss position	47,314		51,909
Continuous unrealized loss position, Gross Unrealized Losses
Available-for-sale securities, continuous loss position for less than 12 months, gross unrealized losses	(68)		(74)
Available-for-sale securities, total gross unrealized losses	(68)		(74)
Auction rate securities
Continuous unrealized loss position, Fair Value
Fair value of available-for-sale securities, continuous loss position for twelve months or greater	5,100		5,340
Total fair value of available-for-sale securities, continuous loss position	5,100		5,340
Continuous unrealized loss position, Gross Unrealized Losses
Available-for-sale securities, continuous loss position for 12 months or greater, gross unrealized losses	(900)		(660)
Available-for-sale securities, total gross unrealized losses	$ (900)		$ (660)