Net (Gain) on Marketable Securities (Detail) - USD ($) $ in Thousands	3 Months Ended
Aug. 31, 2020	Aug. 31, 2019
(In thousands)
Unrealized (gains) on marketable equity securities	$ (13,956)	$ (3,476)
Realized (gains) losses on marketable equity securities	2,169	(68)
Realized losses on available-for-sale debt securities	3	4
Net (gain) on marketable securities	$ (11,784)	$ (3,540)

Amount of realized gain (loss) on investment in debt security measured at fair value with change in fair value recognized in net income (trading).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(7)(c))
-URI http://asc.fasb.org/extlink&oid=120395209&loc=SL114868664-224227

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Amount of unrealized and realized gain (loss) on investment in marketable security, including other-than-temporary impairment (OTTI).

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Amount of realized gain (loss) on investment in marketable security, including other-than-temporary impairment (OTTI).

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Amount of unrealized gain (loss) on investment in marketable security.

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