Cash, Cash Equivalents and Investments (Details 2) (USD $) In Thousands	Oct. 01, 2011	Jan. 01, 2011
Continuous unrealized loss position, Fair Value
Fair value of available-for-sale securities, continuous loss position for less than twelve months	$ 48,574	$ 58,386
Fair value of available-for-sale securities, continuous loss position for twelve month or longer	17,840	18,798
Total fair value of available-for-sale securities, continuous loss position	66,414	77,184
Continuous unrealized loss position, Gross Unrealized Losses
Available-for-sale securities, continuous loss position for less than 12 months, gross unrealized losses	(290)	(69)
Available-for-sale securities, continuous loss position for 12 months or greater, gross unrealized losses	(1,435)	(2,227)
Available-for-sale securities, total gross unrealized losses	(1,725)	(2,296)
Cost
Due in one year or less, Cost	158,008
Due after one year through ten years, Cost	71,265
Due after ten years, Cost	31,175
Total Cost	260,448
Fair Value
Due in one year or less, Fair Value	158,118
Due after one year through ten years, Fair Value	71,225
Due after ten years, Fair Value	29,740
Total Fair Value	259,083
Corporate bonds
Continuous unrealized loss position, Fair Value
Fair value of available-for-sale securities, continuous loss position for less than twelve months	34,577	17,538
Fair value of available-for-sale securities, continuous loss position for twelve month or longer		1,298
Total fair value of available-for-sale securities, continuous loss position	34,577	18,836
Continuous unrealized loss position, Gross Unrealized Losses
Available-for-sale securities, continuous loss position for less than 12 months, gross unrealized losses	(282)	(44)
Available-for-sale securities, continuous loss position for 12 months or greater, gross unrealized losses		(2)
Available-for-sale securities, total gross unrealized losses	(282)	(46)
Auction rate securities
Continuous unrealized loss position, Fair Value
Fair value of available-for-sale securities, continuous loss position for twelve month or longer	17,840	17,500
Total fair value of available-for-sale securities, continuous loss position	17,840	17,500
Continuous unrealized loss position, Gross Unrealized Losses
Available-for-sale securities, continuous loss position for 12 months or greater, gross unrealized losses	(1,435)	(2,225)
Available-for-sale securities, total gross unrealized losses	(1,435)	(2,225)
Municipal bonds
Continuous unrealized loss position, Fair Value
Fair value of available-for-sale securities, continuous loss position for less than twelve months	6,181	22,272
Total fair value of available-for-sale securities, continuous loss position	6,181	22,272
Continuous unrealized loss position, Gross Unrealized Losses
Available-for-sale securities, continuous loss position for less than 12 months, gross unrealized losses	(5)	(18)
Available-for-sale securities, total gross unrealized losses	(5)	(18)
U.S. government agency
Continuous unrealized loss position, Fair Value
Fair value of available-for-sale securities, continuous loss position for less than twelve months	5,003	17,007
Total fair value of available-for-sale securities, continuous loss position	5,003	17,007
Continuous unrealized loss position, Gross Unrealized Losses
Available-for-sale securities, continuous loss position for less than 12 months, gross unrealized losses	(1)	(5)
Available-for-sale securities, total gross unrealized losses	(1)	(5)
Certificates of deposit
Continuous unrealized loss position, Fair Value
Fair value of available-for-sale securities, continuous loss position for less than twelve months	1,569	1,569
Total fair value of available-for-sale securities, continuous loss position	1,569	1,569
Continuous unrealized loss position, Gross Unrealized Losses
Available-for-sale securities, continuous loss position for less than 12 months, gross unrealized losses	(1)	(2)
Available-for-sale securities, total gross unrealized losses	(1)	(2)
Asset-backed securities
Continuous unrealized loss position, Fair Value
Fair value of available-for-sale securities, continuous loss position for less than twelve months	1,244
Total fair value of available-for-sale securities, continuous loss position	1,244
Continuous unrealized loss position, Gross Unrealized Losses
Available-for-sale securities, continuous loss position for less than 12 months, gross unrealized losses	(1)
Available-for-sale securities, total gross unrealized losses	$ (1)