Marketable Securities - Additional Information (Detail) - USD ($) $ in Thousands	Feb. 28, 2019	May 31, 2018
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, current	$ 7,600	$ 97,400
Available-for-sale securities, long-term	16,200	70,700
Equity Securities, Fair Value (Net Carrying Amount)	$ 89,200	144,555
Maximum
Schedule of Available-for-sale Securities [Line Items]
Investments with unrealized loss, percentage of fair values less than original cost	15.00%
Trading Securities
Schedule of Available-for-sale Securities [Line Items]
Securities held in relation to deferred compensation plan	$ 12,400	$ 9,900

Percentage of carrying value over fair value.

No definition available.

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- Definition

Carrying amount as of the balance sheet date of assets held under deferred compensation agreements.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
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- Definition

Amount of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=99377092&loc=SL75136599-209740

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Amount of investment in marketable security, classified as current.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
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Amount of investment in marketable security, classified as noncurrent.

+ References

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-Topic 210
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-Section S99
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- Definition

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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