Cash, Cash Equivalents and Short-Term Marketable Securities (Details 5) (USD $) In Thousands, unless otherwise specified	Jul. 01, 2012	Apr. 01, 2012
Gross unrealized losses and fair values of investments in an unrealized loss position
Fair Value, Less than 12 months	$ 42,889	$ 47,811
Gross Unrealized Losses, Less than 12 months	(264)	(196)
Fair Value, 12 months or greater	4,361	6,203
Gross Unrealized Losses, 12 months or greater	(61)	(90)
Fair Value, Total	47,250	54,014
Gross Unrealized Losses, Total	(325)	(286)
U.S. government and agency securities [Member]
Gross unrealized losses and fair values of investments in an unrealized loss position
Fair Value, Less than 12 months	5,988	16,175
Gross Unrealized Losses, Less than 12 months	(5)	(50)
Fair Value, Total	5,988	16,175
Gross Unrealized Losses, Total	(5)	(50)
Corporate bonds and commercial paper [Member]
Gross unrealized losses and fair values of investments in an unrealized loss position
Fair Value, Less than 12 months	16,374	11,685
Gross Unrealized Losses, Less than 12 months	(75)	(33)
Fair Value, 12 months or greater	201
Gross Unrealized Losses, 12 months or greater	(4)
Fair Value, Total	16,575	11,685
Gross Unrealized Losses, Total	(79)	(33)
Asset-backed securities [Member]
Gross unrealized losses and fair values of investments in an unrealized loss position
Fair Value, Less than 12 months	2,384	3,516
Gross Unrealized Losses, Less than 12 months	(11)	(5)
Fair Value, 12 months or greater	2,035	3,786
Gross Unrealized Losses, 12 months or greater	(18)	(39)
Fair Value, Total	4,419	7,302
Gross Unrealized Losses, Total	(29)	(44)
Mortgage-backed securities [Member]
Gross unrealized losses and fair values of investments in an unrealized loss position
Fair Value, Less than 12 months	18,143	16,435
Gross Unrealized Losses, Less than 12 months	173	108
Fair Value, 12 months or greater	2,125	2,417
Gross Unrealized Losses, 12 months or greater	39	51
Fair Value, Total	20,268	18,852
Gross Unrealized Losses, Total	$ 212	$ 159