Investment Expense (Income), Net - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Nov. 30, 2018	Nov. 30, 2017	Nov. 30, 2018	Nov. 30, 2017
Schedule Of Trading Securities And Other Trading Assets [Line Items]
Gross realized losses on sales of marketable securities	$ 1.0		$ 1.2	$ 1.2
Unrealized losses on trading securities	1.0		1.1
Gross gains realized on sales of marketable securities		$ 2.0	0.2	$ 6.1
Unrealized gains on trading securities			0.5
ASU 2016-01
Schedule Of Trading Securities And Other Trading Assets [Line Items]
Unrealized losses on marketable equity securities	$ 6.5		$ 6.5

Gross realized gains on sales of marketable securities.

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- Definition

Gross realized losses on sales of marketable securities.

+ References

No definition available.

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- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 9
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27357-111563

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

+ References

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- Definition

Amount of unrealized loss on 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 321
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=84241550&loc=SL75117546-209714

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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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