Business Acquisitions - Schedule of Purchase Price Allocation to Net Assets Acquired (Detail) (USD $) In Thousands, unless otherwise specified	Jul. 31, 2013	Apr. 30, 2013	Jul. 31, 2012 BBI Acquisition [Member]
Business Acquisition [Line Items]
Equipment			$ 2,225
Goodwill	115,928	115,928	810
Intangible assets			546
Current liabilities			(81)
Total			$ 3,500

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Amount of liabilities due within one year or within the normal operating cycle, if longer, assumed at the acquisition date.

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Amount of tangible personal property used to produce goods and services, including, but is not limited to, tools, dies and molds, computer and office equipment, acquired at the acquisition date.

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The amount of identifiable intangible assets recognized as of the acquisition date.

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

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Amount recognized for assets, including goodwill, in excess of (less than) the aggregate liabilities assumed.

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Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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-Name Accounting Standards Codification

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