Cash, Cash Equivalents and Investments (Details 2) - USD ($) $ in Thousands	Oct. 03, 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	$ 10,473	$ 51,658
Fair value of available-for-sale securities, continuous loss position for twelve months or longer	7,240	7,419
Total fair value of available-for-sale securities, continuous loss position	17,713	59,077
Continuous unrealized loss position, Gross Unrealized Losses
Available-for-sale securities, continuous loss position for less than 12 months, gross unrealized losses	(13)	(73)
Available-for-sale securities, continuous loss position for 12 months or greater, gross unrealized losses	(760)	(581)
Available-for-sale securities, total gross unrealized losses	(773)	(654)
Cost
Due in one year or less, Cost	139,704
Due after one year through ten years, Cost	33,136
Due after ten years, Cost	14,915
Total Cost	187,755
Fair Value
Due in one year or less, Fair Value	139,779
Due after one year through ten years, Fair Value	33,195
Due after ten years, Fair Value	14,155
Total Fair Value	187,129
Municipal bonds
Continuous unrealized loss position, Fair Value
Fair value of available-for-sale securities, continuous loss position for less than twelve months	8,274	23,735
Total fair value of available-for-sale securities, continuous loss position	8,274	23,735
Continuous unrealized loss position, Gross Unrealized Losses
Available-for-sale securities, continuous loss position for less than 12 months, gross unrealized losses	(10)	(25)
Available-for-sale securities, total gross unrealized losses	(10)	(25)
Corporate bonds
Continuous unrealized loss position, Fair Value
Fair value of available-for-sale securities, continuous loss position for less than twelve months		20,327
Total fair value of available-for-sale securities, continuous loss position		20,327
Continuous unrealized loss position, Gross Unrealized Losses
Available-for-sale securities, continuous loss position for less than 12 months, gross unrealized losses		(35)
Available-for-sale securities, total gross unrealized losses		(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	7,240	7,419
Total fair value of available-for-sale securities, continuous loss position	7,240	7,419
Continuous unrealized loss position, Gross Unrealized Losses
Available-for-sale securities, continuous loss position for 12 months or greater, gross unrealized losses	(760)	(581)
Available-for-sale securities, total gross unrealized losses	(760)	(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	2,199	2,516
Total fair value of available-for-sale securities, continuous loss position	2,199	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)