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Additional Information Pertaining to Stock Options (Detail) (USD $) In Thousands, unless otherwise specified | 3 Months Ended
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Jul. 31, 2013 | Jul. 31, 2012
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items] |  |
Total fair value of stock options vested | $ 802 | $ 829
Total intrinsic value of stock options exercised | $ 1,664 | $ 160

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- Definition Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (d)(2) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition Fair value of options vested. Excludes equity instruments other than options, for example, but not limited to, share units, stock appreciation rights, restricted stock. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Details
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