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Financial Instruments - Additional Information (Detail) - USD ($) | 1 Months Ended | 3 Months Ended | 9 Months Ended |
--- | --- | --- | --- | ---
Mar. 31, 2017 | Jan. 31, 2019 | Jan. 31, 2018 | Jan. 31, 2019 | Jan. 31, 2018 | Apr. 30, 2018
Maximum |  |  |  |  |  |
Financial Instrument [Line Items] |  |  |  |  |  |
Derivative gains included in accumulated other comprehensive income |  |  |  | $ 600,000 |  |
Designated as Hedge Instrument | Interest Rate Swap | Cash Flow Hedge |  |  |  |  |  |
Financial Instrument [Line Items] |  |  |  |  |  |
Derivative notional amount | $ 129,800,000 | $ 110,000,000 |  | $ 110,000,000 |  |
Derivative, Maturity Date | Jun. 15, 2021 |  |  |  |  |
Interest rate |  | 1.919% |  | 1.919% |  |
Not Designated as Hedge Instrument | Foreign Exchange Forward Contracts |  |  |  |  |  |
Financial Instrument [Line Items] |  |  |  |  |  |
Foreign currency gains (losses) |  | $ 700,000 | $ (1,900,000) | $ 600,000 | $ (4,200,000) |
Not Designated as Hedge Instrument | Foreign Exchange Forward Contracts | Other Accrued Liabilities | Derivatives Purchased |  |  |  |  |  |
Financial Instrument [Line Items] |  |  |  |  |  |
Derivative notional amount |  | 48,400,000 |  | 48,400,000 |  | $ 80,800,000
Not Designated as Hedge Instrument | Foreign Exchange Forward Contracts | Other Accrued Liabilities | Derivatives Sold |  |  |  |  |  |
Financial Instrument [Line Items] |  |  |  |  |  |
Derivative notional amount |  | $ 45,900,000 |  | $ 45,900,000 |  | $ 78,500,000

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- Definition Aggregate notional amount specified by the derivative(s). Expressed as an absolute value. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Article 12 -Section 13 -Sentence Column B + Details
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- Definition Financial Instrument [Line Items] + References No definition available. + Details
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- Definition The estimated net amount of existing gains or losses on cash flow hedges at the reporting date expected to be reclassified to earnings within the next 12 months. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 30 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=112277219&loc=d3e80748-113994 + Details
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- Definition Fixed interest rate related to the interest rate derivative. + References No definition available. + Details
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- Definition Amount of realized and unrealized gain (loss) of derivative instruments not designated or qualifying as hedging instruments. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4CC -URI http://asc.fasb.org/extlink&oid=109980867&loc=SL109998890-113959 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4C -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5624171-113959 + Details
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- Definition Date the derivative contract matures, in CCYY-MM-DD format. + References No definition available. + Details
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