Fair Value of Financial Instruments - Contractual maturities of investments (Details) - USD ($) $ in Thousands	Oct. 02, 2021	Jan. 02, 2021
Cost
Due in one year or less, Cost	$ 1,024,156
Due after one year through ten years, Cost	365,147
Due after ten years, Cost	6,000
Total Cost	1,395,303
Fair Value
Due in one year or less, Fair Value	1,024,471
Due after one year through ten years, Fair Value	365,079
Due after ten years, Fair Value	5,100
Total Fair Value	1,394,650
Continuous unrealized loss position, Fair Value
Fair value of available-for-sale securities, continuous loss position for less than twelve months	623,573	$ 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	628,673	67,395
Continuous unrealized loss position, Gross Unrealized Losses
Available-for-sale securities, continuous loss position for less than 12 months, gross unrealized losses	(311)	(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	(1,211)	(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	373,994	10,146
Total fair value of available-for-sale securities, continuous loss position	373,994	10,146
Continuous unrealized loss position, Gross Unrealized Losses
Available-for-sale securities, continuous loss position for less than 12 months, gross unrealized losses	(59)	(5)
Available-for-sale securities, total gross unrealized losses	(59)	(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	249,579	51,909
Total fair value of available-for-sale securities, continuous loss position	249,579	51,909
Continuous unrealized loss position, Gross Unrealized Losses
Available-for-sale securities, continuous loss position for less than 12 months, gross unrealized losses	(252)	(74)
Available-for-sale securities, total gross unrealized losses	(252)	(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)