Gain on Sale of Idle Property, Plant and Equipment - Additional Information (Detail) (USD $)	3 Months Ended	9 Months Ended	3 Months Ended
Feb. 28, 2014	Feb. 28, 2014	Feb. 28, 2013	Nov. 30, 2013 Fair Haven, Vermont [Member]	Feb. 28, 2014 Halstead Kansas [Member]	Nov. 30, 2012 Hemet California [Member] Facility
Gain (Loss) on Investments [Line Items]
Gain on the sale of idle facilities	$ 300,000	$ 462,000	$ 1,411,000	$ 162,000	$ 300,000	$ 1,411,000
Number of idle facilities sold						2

Amount of gain (loss) on sale or disposal of property, plant and equipment assets, including oil and gas property and timber property.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585

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