Note 2 - Marketable Securities - Summary of Realized Gains/Losses on Available-for-Sale Securities (Details) - USD ($) $ in Thousands	12 Months Ended
Feb. 25, 2018	Feb. 26, 2017	Feb. 28, 2016
Gross realized gains on sale
Gross realized losses on sale	$ 1,342

This item represents the gross profit realized on the sale of debt or equity securities categorized neither as held-to-maturity nor trading securities.

No definition available.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration