Assets Held for Sale - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	Aug. 31, 2014 acre	May 31, 2014
Long Lived Assets Held-for-sale [Line Items]
Land held for sale	$ 5,207	$ 5,207
Purchase land planned to construct future facilities in area	50

Amount classified as property, plant and equipment attributable to disposal group held for sale or disposed of, expected to be disposed of after one year or the normal operating cycle, if longer.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant