Investment Securities (Schedule Of Investment Securities) (Details) - USD ($) $ in Thousands	Aug. 31, 2019	Jun. 01, 2019
Current investments
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 188,953	$ 249,875
Unrealized Gains	747	315
Unrealized Losses	0	9
Estimated Fair Value	189,700	250,181
Noncurrent investments
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1,899	2,331
Unrealized Gains	713	1,026
Unrealized Losses	0	0
Estimated Fair Value	2,612	3,357
US government and agency obligations \| Current investments
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	30,943	30,896
Unrealized Gains	173	78
Unrealized Losses	0	0
Estimated Fair Value	31,116	30,974
Municipal bonds \| Current investments
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	34,632	50,220
Unrealized Gains	200	133
Unrealized Losses	0	0
Estimated Fair Value	34,832	50,353
Commercial Paper [Member] \| Current investments
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	2,990	9,953
Unrealized Gains	1	0
Unrealized Losses	0	8
Estimated Fair Value	2,991	9,945
Corporate bonds \| Current investments
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	116,061	147,068
Unrealized Gains	359	94
Unrealized Losses	0	0
Estimated Fair Value	116,420	147,162
Certificates of deposits \| Current investments
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1,004	6,149
Unrealized Gains	0	0
Unrealized Losses	0	1
Estimated Fair Value	1,004	6,148
Asset backed securities \| Current investments
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	3,323	5,589
Unrealized Gains	14	10
Unrealized Losses	0	0
Estimated Fair Value	3,337	5,599
Mutual funds \| Noncurrent investments
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1,899	2,331
Unrealized Gains	713	1,026
Unrealized Losses	0	0
Estimated Fair Value	$ 2,612	$ 3,357

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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- Definition

Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27161-111563

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Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

+ References

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+ References

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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