Income Before Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
May. 31, 2015	May. 31, 2014	May. 31, 2013
Income Before Income Taxes [Line Items]
Income Before Income Taxes	$ 52,076	$ 43,031	$ 41,141
U.S.
Income Before Income Taxes [Line Items]
Income Before Income Taxes	45,156	37,568	37,407
Foreign
Income Before Income Taxes [Line Items]
Income Before Income Taxes	$ 6,920	$ 5,463	$ 3,734

Sum of operating profit and nonoperating income or expense before Income or Loss from equity method investments, income taxes, extraordinary items, and noncontrolling interest.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-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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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration