Cash, Cash Equivalents and Investments - Continuous Unrealized Loss Position (Details) - USD ($) $ in Thousands	Apr. 02, 2016	Jan. 02, 2016
Continuous unrealized loss position, Fair Value
Fair value of available-for-sale securities, continuous loss position for less than twelve months	$ 35,770	$ 32,487
Fair value of available-for-sale securities, continuous loss position for twelve months or longer	9,553	8,324
Total fair value of available-for-sale securities, continuous loss position	45,323	40,811
Continuous unrealized loss position, Gross Unrealized Losses
Available-for-sale securities, continuous loss position for less than 12 months, gross unrealized losses	(29)	(40)
Available-for-sale securities, continuous loss position for 12 months or greater, gross unrealized losses	(1,158)	(876)
Available-for-sale securities, total gross unrealized losses	(1,187)	(916)
Cost
Due in one year or less, Cost	114,458
Due after one year through ten years, Cost	41,002
Due after ten years, Cost	29,825
Total Cost	185,285
Fair Value
Due in one year or less, Fair Value	114,470
Due after one year through ten years, Fair Value	41,022
Due after ten years, Fair Value	28,670
Total Fair Value	184,162
Municipal bonds
Continuous unrealized loss position, Fair Value
Fair value of available-for-sale securities, continuous loss position for less than twelve months	27,767	29,271
Fair value of available-for-sale securities, continuous loss position for twelve months or longer	2,708	1,198
Total fair value of available-for-sale securities, continuous loss position	30,475	30,469
Continuous unrealized loss position, Gross Unrealized Losses
Available-for-sale securities, continuous loss position for less than 12 months, gross unrealized losses	(11)	(30)
Available-for-sale securities, continuous loss position for 12 months or greater, gross unrealized losses	(3)	(2)
Available-for-sale securities, total gross unrealized losses	(14)	(32)
Auction rate securities
Continuous unrealized loss position, Fair Value
Fair value of available-for-sale securities, continuous loss position for twelve months or longer	6,845	7,126
Total fair value of available-for-sale securities, continuous loss position	6,845	7,126
Continuous unrealized loss position, Gross Unrealized Losses
Available-for-sale securities, continuous loss position for 12 months or greater, gross unrealized losses	(1,155)	(874)
Available-for-sale securities, total gross unrealized losses	(1,155)	(874)
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
Total fair value of available-for-sale securities, continuous loss position		2,220
Continuous unrealized loss position, Gross Unrealized Losses
Available-for-sale securities, continuous loss position for less than 12 months, gross unrealized losses		(7)
Available-for-sale securities, total gross unrealized losses		(7)
Corporate bonds
Continuous unrealized loss position, Fair Value
Fair value of available-for-sale securities, continuous loss position for less than twelve months	8,003	996
Total fair value of available-for-sale securities, continuous loss position	8,003	996
Continuous unrealized loss position, Gross Unrealized Losses
Available-for-sale securities, continuous loss position for less than 12 months, gross unrealized losses	(18)	(3)
Available-for-sale securities, total gross unrealized losses	$ (18)	$ (3)