Note 2 - Marketable Securities - Summary of Unrealized Gains/Losses on Available-for-sale Securities (Details) - USD ($) $ in Thousands	12 Months Ended
Feb. 26, 2017	Feb. 28, 2016
Amortized Cost Basis	$ 136,665	$ 139,451
Gross Unrealized Gains	137	372
Gross Unrealized Losses	650	155
US Treasury and Government [Member]
Amortized Cost Basis	111,727	117,897
Gross Unrealized Gains	136	372
Gross Unrealized Losses	602	74
Domestic Corporate Debt Securities [Member]
Amortized Cost Basis	24,938	21,554
Gross Unrealized Gains	1
Gross Unrealized Losses	$ 48	$ 81

This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.2)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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- Definition

Amount of unrealized gain before deducting unrealized loss on investments in debt and equity securities classified as available-for-sale securities.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27161-111563

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- Definition

Amount of unrealized loss before deducting unrealized gain on investments in available-for-sale securities.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27161-111563

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