Cash, Cash Equivalents and Investments (Details 2) (USD $) In Thousands, unless otherwise specified	Dec. 28, 2013	Dec. 29, 2012
Continuous unrealized loss position, Fair Value
Fair value of available-for-sale securities, continuous loss position for less than twelve months	$ 13,684	$ 26,695
Fair value of available-for-sale securities, continuous loss position for twelve months or longer	10,632	11,369
Total fair value of available-for-sale securities, continuous loss position	24,316	38,064
Continuous unrealized loss position, Gross Unrealized Losses
Available-for-sale securities, continuous loss position for less than 12 months, gross unrealized losses	(15)	(12)
Available-for-sale securities, continuous loss position for 12 months or greater, gross unrealized losses	(1,793)	(1,156)
Available-for-sale securities, total gross unrealized losses	(1,808)	(1,168)
Cost
Due in one year or less, Cost	115,109
Due after one year through ten years, Cost	80,987
Due after ten years, Cost	45,950
Total Cost	242,046
Fair Value
Due in one year or less, Fair Value	115,177
Due after one year through ten years, Fair Value	81,147
Due after ten years, Fair Value	44,157
Total Fair Value	240,481
Municipal bonds
Continuous unrealized loss position, Fair Value
Fair value of available-for-sale securities, continuous loss position for less than twelve months	11,079	17,152
Total fair value of available-for-sale securities, continuous loss position	11,079	17,152
Continuous unrealized loss position, Gross Unrealized Losses
Available-for-sale securities, continuous loss position for less than 12 months, gross unrealized losses	(11)	(7)
Available-for-sale securities, total gross unrealized losses	(11)	(7)
Auction rate securities
Continuous unrealized loss position, Fair Value
Fair value of available-for-sale securities, continuous loss position for twelve months or longer	10,632	11,369
Total fair value of available-for-sale securities, continuous loss position	10,632	11,369
Continuous unrealized loss position, Gross Unrealized Losses
Available-for-sale securities, continuous loss position for 12 months or greater, gross unrealized losses	(1,793)	(1,156)
Available-for-sale securities, total gross unrealized losses	(1,793)	(1,156)
Corporate bonds
Continuous unrealized loss position, Fair Value
Fair value of available-for-sale securities, continuous loss position for less than twelve months	2,605	9,543
Total fair value of available-for-sale securities, continuous loss position	2,605	9,543
Continuous unrealized loss position, Gross Unrealized Losses
Available-for-sale securities, continuous loss position for less than 12 months, gross unrealized losses	(4)	(5)
Available-for-sale securities, total gross unrealized losses	$ (4)	$ (5)