Note 5 - Fair Value (Details) - Cash, Cash Equivalents and Short-term Marketable Securities (USD $) In Thousands, unless otherwise specified	Dec. 28, 2014	Mar. 30, 2014	Dec. 29, 2013	Mar. 31, 2013
Cash and cash equivalents
Cash at financial institutions	$ 52,616	$ 9,978
Cash equivalents
Money market funds	6	4,636
Total cash and cash equivalents	52,622	14,614	21,070	14,718
Available-for-sale securities
Short-term marketable securities		152,420
US Government Agencies Debt Securities [Member]
Available-for-sale securities
Short-term marketable securities		22,512
US States and Political Subdivisions Debt Securities [Member]
Available-for-sale securities
Short-term marketable securities		2,772
Corporate Debt Securities [Member]
Available-for-sale securities
Short-term marketable securities		71,253
Asset-backed Securities [Member]
Available-for-sale securities
Short-term marketable securities		27,635
Collateralized Mortgage Backed Securities [Member]
Available-for-sale securities
Short-term marketable securities		$ 28,248