Cash, Cash Equivalents and Investments (Details 2) (USD $) In Thousands, unless otherwise specified	Apr. 01, 2012
Gross unrealized losses and fair value for available-for-sale investments
Fair Value, Less than 12 months	$ 35,122
Unrealized Losses, Less than 12 months	(75)
Fair Value, 12 months or greater	8,758
Unrealized Losses, 12 months or greater	(129)
Fair Value	43,880
Unrealized Losses	(204)
Municipal bonds [Member]
Gross unrealized losses and fair value for available-for-sale investments
Fair Value, Less than 12 months	19,415
Unrealized Losses, Less than 12 months	(29)
Fair Value	19,415
Unrealized Losses	(29)
Agency bonds [Member]
Gross unrealized losses and fair value for available-for-sale investments
Fair Value, Less than 12 months	11,772
Unrealized Losses, Less than 12 months	(44)
Fair Value	11,772
Unrealized Losses	(44)
Corporate bonds [Member]
Gross unrealized losses and fair value for available-for-sale investments
Fair Value, Less than 12 months	3,935
Unrealized Losses, Less than 12 months	(2)
Fair Value, 12 months or greater	8,758
Unrealized Losses, 12 months or greater	(129)
Fair Value	12,693
Unrealized Losses	$ (131)