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Financial Instruments - Additional Information (Detail) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Apr. 30, 2022 | Apr. 30, 2021 | Apr. 30, 2020
Financial Instrument [Line Items] |  |  |
Sale/maturities of available-for-sale marketable securities | $ 79.3 | $ 60.6 | $ 4.8
Unrealized loss relates to equity securities | 27.3 |  | 8.2
Unrealized gains relates to equity securities |  | 32.7 |
Not Designated as Hedge Instrument | Foreign Exchange Forward Contracts |  |  |
Financial Instrument [Line Items] |  |  |
Foreign currency gains (losses) | (0.2) | 2.7 | $ (0.3)
Not Designated as Hedge Instrument | Foreign Exchange Forward Contracts | Income Taxes And Other Receivables | Derivatives Purchased |  |  |
Financial Instrument [Line Items] |  |  |
Derivative notional amount | 89.7 | 69.4 |
Not Designated as Hedge Instrument | Foreign Exchange Forward Contracts | Income Taxes And Other Receivables | Derivatives Sold |  |  |
Financial Instrument [Line Items] |  |  |
Derivative notional amount | $ 35.8 | $ 44.9 |
Available-for-sale Marketable Securities | Minimum |  |  |
Financial Instrument [Line Items] |  |  |
Marketable securities remaining maturity | 1 month |  |
Available-for-sale Marketable Securities | Maximum |  |  |
Financial Instrument [Line Items] |  |  |
Marketable securities remaining maturity | 21 months |  |

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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=125515794&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=125515794&loc=SL5624171-113959 + Details
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