Cash, Cash Equivalents and Investments - Continuous Unrealized Loss Position (Details) - USD ($) $ in Thousands	Jan. 02, 2016	Jan. 03, 2015
Continuous unrealized loss position, Fair Value
Fair value of available-for-sale securities, continuous loss position for less than twelve months	$ 32,487	$ 51,658
Fair value of available-for-sale securities, continuous loss position for twelve months or longer	8,324	7,419
Total fair value of available-for-sale securities, continuous loss position	40,811	59,077
Continuous unrealized loss position, Gross Unrealized Losses
Available-for-sale securities, continuous loss position for less than 12 months, gross unrealized losses	(40)	(73)
Available-for-sale securities, continuous loss position for 12 months or greater, gross unrealized losses	(876)	(581)
Available-for-sale securities, total gross unrealized losses	(916)	(654)
Cost
Due in one year or less, Cost	150,455
Due after one year through ten years, Cost	26,113
Due after ten years, Cost	15,345
Total Cost	191,913
Fair Value
Due in one year or less, Fair Value	150,477
Due after one year through ten years, Fair Value	26,093
Due after ten years, Fair Value	14,471
Total Fair Value	191,041
Municipal bonds
Continuous unrealized loss position, Fair Value
Fair value of available-for-sale securities, continuous loss position for less than twelve months	29,271	23,735
Fair value of available-for-sale securities, continuous loss position for twelve months or longer	1,198
Total fair value of available-for-sale securities, continuous loss position	30,469	23,735
Continuous unrealized loss position, Gross Unrealized Losses
Available-for-sale securities, continuous loss position for less than 12 months, gross unrealized losses	(30)	(25)
Available-for-sale securities, continuous loss position for 12 months or greater, gross unrealized losses	(2)
Available-for-sale securities, total gross unrealized losses	(32)	(25)
Corporate bonds
Continuous unrealized loss position, Fair Value
Fair value of available-for-sale securities, continuous loss position for less than twelve months	996	20,327
Total fair value of available-for-sale securities, continuous loss position	996	20,327
Continuous unrealized loss position, Gross Unrealized Losses
Available-for-sale securities, continuous loss position for less than 12 months, gross unrealized losses	(3)	(35)
Available-for-sale securities, total gross unrealized losses	(3)	(35)
Auction rate securities
Continuous unrealized loss position, Fair Value
Fair value of available-for-sale securities, continuous loss position for twelve months or longer	7,126	7,419
Total fair value of available-for-sale securities, continuous loss position	7,126	7,419
Continuous unrealized loss position, Gross Unrealized Losses
Available-for-sale securities, continuous loss position for 12 months or greater, gross unrealized losses	(874)	(581)
Available-for-sale securities, total gross unrealized losses	(874)	(581)
Asset-backed securities
Continuous unrealized loss position, Fair Value
Fair value of available-for-sale securities, continuous loss position for less than twelve months		5,080
Total fair value of available-for-sale securities, continuous loss position		5,080
Continuous unrealized loss position, Gross Unrealized Losses
Available-for-sale securities, continuous loss position for less than 12 months, gross unrealized losses		(3)
Available-for-sale securities, total gross unrealized losses		(3)
International government bonds
Continuous unrealized loss position, Fair Value
Fair value of available-for-sale securities, continuous loss position for less than twelve months	2,220	2,516
Total fair value of available-for-sale securities, continuous loss position	2,220	2,516
Continuous unrealized loss position, Gross Unrealized Losses
Available-for-sale securities, continuous loss position for less than 12 months, gross unrealized losses	(7)	(10)
Available-for-sale securities, total gross unrealized losses	$ (7)	$ (10)