Note 4 - Fair Value (Details) - Summary of Investments in Marketable Securities (USD $) In Thousands, unless otherwise specified	9 Months Ended		12 Months Ended
	Dec. 29, 2013		Mar. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 168,788		$ 195,300
Unrealized Gross Gains	99	[1]	507	[1]
Unrealized Gross Losses	(224)	[1]	(178)	[1]
Fair Value	168,663		195,629
US Government Corporation And Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	32,840		41,694
Unrealized Gross Gains	1	[1]	27	[1]
Unrealized Gross Losses	(50)	[1]		[1]
Fair Value	32,791		41,721
US States and Political Subdivisions Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	2,797		2,927
Unrealized Gross Gains	5	[1]	10	[1]
Unrealized Gross Losses	(4)	[1]	(2)	[1]
Fair Value	2,798		2,935
Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	72,730		92,059
Unrealized Gross Gains	60	[1]	215	[1]
Unrealized Gross Losses	(65)	[1]	(45)	[1]
Fair Value	72,725		92,229
Asset-backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	30,396		30,932
Unrealized Gross Gains	14	[1]	61	[1]
Unrealized Gross Losses	(56)	[1]	(27)	[1]
Fair Value	30,354		30,966
Collateralized Mortgage Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	16,064		22,646
Unrealized Gross Gains	19	[1]	194	[1]
Unrealized Gross Losses	(49)	[1]	(104)	[1]
Fair Value	16,034		22,736
Money Market Funds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	13,961		5,042
Unrealized Gross Gains		[1]		[1]
Unrealized Gross Losses		[1]		[1]
Fair Value	$ 13,961		$ 5,042

[1] Gross of tax impact