Unconsolidated Subsidiaries - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
May. 31, 2015	May. 31, 2014
Schedule of Equity Method Investments [Line Items]
Percentage of ownership in joint venture	50.00%
Equity method investment unconsolidated subsidiaries sales revenues	$ 0.0	$ 8.5

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 323

-SubTopic 10

-Section 50

-Paragraph 3

-Subparagraph (a)(1)

-URI http://asc.fasb.org/extlink&oid=6382943&loc=d3e33918-111571

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant