Unconsolidated Subsidiaries - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
May 31, 2013	May 31, 2012	May 31, 2008
Schedule of Equity Method Investments [Line Items]
Percentage of ownership in joint venture			50.00%
Investment in the net assets of the joint venture	$ 1.8	$ 1.8
Equity Method Investment Unconsolidated Subsidiaries Sales Revenues	$ 13.5	$ 12.3

This element represents the aggregate cost of investments accounted for under the equity method of accounting.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.12)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 12

-Article 5

+ Details

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- Definition

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

+ References

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

+ Details

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- Definition

The amount of revenue from sale of goods and services reduced by sales returns, allowances, and discounts reported by an equity method investment of the entity.

+ References

No definition available.

+ Details

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Balance Type:	credit
Period Type:	duration

- Details

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