Income Before Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
May 31, 2018	May 31, 2017	May 31, 2016
Income Before Income Taxes [Line Items]
Income Before Income Taxes	$ 73,465	$ 66,673	$ 55,513
U.S.
Income Before Income Taxes [Line Items]
Income Before Income Taxes	62,310	55,171	50,662
Foreign
Income Before Income Taxes [Line Items]
Income Before Income Taxes	$ 11,155	$ 11,502	$ 4,851

Amount of income (loss) from continuing operations before deduction of income tax expense (benefit) and income (loss) attributable to noncontrolling interest, and addition of income (loss) from equity method investments.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(h)(1)(i))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration