Note 6. Cash, Cash Equivalents and Short Term Marketable Securities (Detail) - Summary of the Gross Unrealized Losses and Fair Values of Investments (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Apr. 01, 2012
Fair Value Less than 12 Months	$ 42,528	$ 47,811
Gross Unrealized Losses Less than 12 Months	(98)	(196)
Fair Value Greater than 12 Months	5,405	6,203
Gross Unrealized Losses Greater than 12 Months	(80)	(90)
Fair Value Total	47,933	54,014
Gross Unrealized Losses Total	(178)	(286)
US States and Political Subdivisions Debt Securities [Member]
Fair Value Less than 12 Months		590
Gross Unrealized Losses Less than 12 Months		(20)
Fair Value Greater than 12 Months	404
Gross Unrealized Losses Greater than 12 Months	(2)
Fair Value Total	404	590
Gross Unrealized Losses Total	(2)	(20)
Corporate Debt Securities [Member]
Fair Value Less than 12 Months	29,609	11,685
Gross Unrealized Losses Less than 12 Months	(42)	(33)
Fair Value Greater than 12 Months	497
Gross Unrealized Losses Greater than 12 Months	(3)
Fair Value Total	30,106	11,685
Gross Unrealized Losses Total	(45)	(33)
Asset-backed Securities [Member]
Fair Value Less than 12 Months	10,008	3,516
Gross Unrealized Losses Less than 12 Months	(17)	(5)
Fair Value Greater than 12 Months	1,241	3,786
Gross Unrealized Losses Greater than 12 Months	(10)	(39)
Fair Value Total	11,249	7,302
Gross Unrealized Losses Total	(27)	(44)
Collateralized Mortgage Backed Securities [Member]
Fair Value Less than 12 Months	2,911	16,435
Gross Unrealized Losses Less than 12 Months	(39)	(108)
Fair Value Greater than 12 Months	3,263	2,417
Gross Unrealized Losses Greater than 12 Months	(65)	(51)
Fair Value Total	6,174	18,852
Gross Unrealized Losses Total	(104)	(159)
US Government Corporations and Agencies Securities [Member]
Fair Value Less than 12 Months		15,585
Gross Unrealized Losses Less than 12 Months		(30)
Fair Value Total		15,585
Gross Unrealized Losses Total		$ (30)