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Commitments and Contingencies - Additional Information (Detail) (USD $) In Millions, unless otherwise specified | 3 Months Ended
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Jul. 31, 2013
Loss Contingencies [Line Items] |
Employment dispute liability | $ 2.5

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- Definition Amount charged against operating income increasing loss contingency liability, after adjustments to reduce previously estimated charges. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14326-108349 + Details
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