Fair Value of Financial Instruments - Contractual maturities of investments (Details) - USD ($) $ in Thousands	Jan. 01, 2022	Jan. 02, 2021
Cost
Due in one year or less, Cost	$ 578,734
Due after one year through ten years, Cost	394,391
Due after ten years, Cost	6,000
Total Cost	979,125
Fair Value
Due in one year or less, Fair Value	578,666
Due after one year through ten years, Fair Value	392,417
Due after ten years, Fair Value	4,980
Total Fair Value	976,063
Continuous unrealized loss position, Fair Value
Fair value of available-for-sale securities, continuous loss position for less than twelve months	545,874	$ 62,055
Fair value of available-for-sale securities, continuous loss position for twelve months or greater	5,306	5,340
Total fair value of available-for-sale securities, continuous loss position	551,180	67,395
Continuous unrealized loss position, Gross Unrealized Losses
Available-for-sale securities, continuous loss position for less than 12 months, gross unrealized losses	(2,201)	(79)
Available-for-sale securities, continuous loss position for 12 months or greater, gross unrealized losses	(1,021)	(660)
Available-for-sale securities, total gross unrealized losses	(3,222)	(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	126,957	10,146
Total fair value of available-for-sale securities, continuous loss position	126,957	10,146
Continuous unrealized loss position, Gross Unrealized Losses
Available-for-sale securities, continuous loss position for less than 12 months, gross unrealized losses	(750)	(5)
Available-for-sale securities, total gross unrealized losses	(750)	(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	418,917	51,909
Fair value of available-for-sale securities, continuous loss position for twelve months or greater	326
Total fair value of available-for-sale securities, continuous loss position	419,243	51,909
Continuous unrealized loss position, Gross Unrealized Losses
Available-for-sale securities, continuous loss position for less than 12 months, gross unrealized losses	(1,451)	(74)
Available-for-sale securities, continuous loss position for 12 months or greater, gross unrealized losses	(1)
Available-for-sale securities, total gross unrealized losses	(1,452)	(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	4,980	5,340
Total fair value of available-for-sale securities, continuous loss position	4,980	5,340
Continuous unrealized loss position, Gross Unrealized Losses
Available-for-sale securities, continuous loss position for 12 months or greater, gross unrealized losses	(1,020)	(660)
Available-for-sale securities, total gross unrealized losses	$ (1,020)	$ (660)