Note 2 - Marketable Securities - Summary of Realized Gains (Losses) on Available-for-Sale Securities (Details) - USD ($) $ in Thousands	12 Months Ended
Feb. 26, 2023	Feb. 27, 2022	Feb. 28, 2021
Gross realized gains on sale	$ 0	$ 26	$ 155
Gross realized losses on sale	$ 5	$ 36	$ 145

Amount of realized gain on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 9
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-9

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