Cash, Cash Equivalents and Investments (Details 2) - USD ($) $ in Thousands	Jul. 04, 2015	Jan. 03, 2015
Continuous unrealized loss position, Fair Value
Fair value of available-for-sale securities, continuous loss position for less than twelve months	$ 35,238	$ 51,658
Fair value of available-for-sale securities, continuous loss position for twelve months or longer	7,179	7,419
Total fair value of available-for-sale securities, continuous loss position	42,417	59,077
Continuous unrealized loss position, Gross Unrealized Losses
Available-for-sale securities, continuous loss position for less than 12 months, gross unrealized losses	(54)	(73)
Available-for-sale securities, continuous loss position for 12 months or greater, gross unrealized losses	(821)	(581)
Available-for-sale securities, total gross unrealized losses	(875)	(654)
Cost
Due in one year or less, Cost	157,646
Due after one year through ten years, Cost	37,754
Due after ten years, Cost	19,715
Total Cost	215,115
Fair Value
Due in one year or less, Fair Value	157,704
Due after one year through ten years, Fair Value	37,739
Due after ten years, Fair Value	18,894
Total Fair Value	214,337
Municipal bonds
Continuous unrealized loss position, Fair Value
Fair value of available-for-sale securities, continuous loss position for less than twelve months	26,686	23,735
Total fair value of available-for-sale securities, continuous loss position	26,686	23,735
Continuous unrealized loss position, Gross Unrealized Losses
Available-for-sale securities, continuous loss position for less than 12 months, gross unrealized losses	(45)	(25)
Available-for-sale securities, total gross unrealized losses	(45)	(25)
Corporate bonds
Continuous unrealized loss position, Fair Value
Fair value of available-for-sale securities, continuous loss position for less than twelve months	6,315	20,327
Total fair value of available-for-sale securities, continuous loss position	6,315	20,327
Continuous unrealized loss position, Gross Unrealized Losses
Available-for-sale securities, continuous loss position for less than 12 months, gross unrealized losses	(6)	(35)
Available-for-sale securities, total gross unrealized losses	(6)	(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	7,179	7,419
Total fair value of available-for-sale securities, continuous loss position	7,179	7,419
Continuous unrealized loss position, Gross Unrealized Losses
Available-for-sale securities, continuous loss position for 12 months or greater, gross unrealized losses	(821)	(581)
Available-for-sale securities, total gross unrealized losses	(821)	(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	2,237	2,516
Total fair value of available-for-sale securities, continuous loss position	2,237	2,516
Continuous unrealized loss position, Gross Unrealized Losses
Available-for-sale securities, continuous loss position for less than 12 months, gross unrealized losses	(3)	(10)
Available-for-sale securities, total gross unrealized losses	$ (3)	$ (10)