| **Derivative financial instruments - Outstanding Currency, Forward Exchange Contracts (Detail) - Foreign Currency Forward Contracts - USD ($) $ in Thousands** | Apr. 30, 2022 | Apr. 30, 2021 |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------|---------------|---------------|
| Sell                                                                                                                                                           |          |          |
| **Derivative [Line Items]**                                                                                                                                    |          |          |
| Notional Amounts of foreign currency derivative contracts                                                                                                      | $ 169,360     | $ 174,189     |
| Buy                                                                                                                                                            |          |          |
| **Derivative [Line Items]**                                                                                                                                    |          |          |
| Notional Amounts of foreign currency derivative contracts                                                                                                      | 631,871       | 581,318       |
| Euro | Sell                                                                                                                                                    |          |          |
| **Derivative [Line Items]**                                                                                                                                    |          |          |
| Notional Amounts of foreign currency derivative contracts                                                                                                      | 96,436        | 127,660       |
| Euro | Buy                                                                                                                                                     |          |          |
| **Derivative [Line Items]**                                                                                                                                    |          |          |
| Notional Amounts of foreign currency derivative contracts                                                                                                      | 337,291       | 309,020       |
| British pound | Sell                                                                                                                                           |          |          |
| **Derivative [Line Items]**                                                                                                                                    |          |          |
| Notional Amounts of foreign currency derivative contracts                                                                                                      | 38,478        | 21,228        |
| British pound | Buy                                                                                                                                            |          |          |
| **Derivative [Line Items]**                                                                                                                                    |          |          |
| Notional Amounts of foreign currency derivative contracts                                                                                                      | 80,853        | 79,446        |
| Japanese yen | Sell                                                                                                                                            |          |          |
| **Derivative [Line Items]**                                                                                                                                    |          |          |
| Notional Amounts of foreign currency derivative contracts                                                                                                      | 10,848        | 12,228        |
| Japanese yen | Buy                                                                                                                                             |          |          |
| **Derivative [Line Items]**                                                                                                                                    |          |          |
| Notional Amounts of foreign currency derivative contracts                                                                                                      | 39,294        | 38,648        |
| Australian dollar | Sell                                                                                                                                       |          |          |
| **Derivative [Line Items]**                                                                                                                                    |          |          |
| Notional Amounts of foreign currency derivative contracts                                                                                                      | 295           | 194           |
| Australian dollar | Buy                                                                                                                                        |          |          |
| **Derivative [Line Items]**                                                                                                                                    |          |          |
| Notional Amounts of foreign currency derivative contracts                                                                                                      | 9,269         | 10,240        |
| Hong Kong dollar | Sell                                                                                                                                        |          |          |
| **Derivative [Line Items]**                                                                                                                                    |          |          |
| Notional Amounts of foreign currency derivative contracts                                                                                                      | 7,727         | 978           |
| Hong Kong dollar | Buy                                                                                                                                         |          |          |
| **Derivative [Line Items]**                                                                                                                                    |          |          |
| Notional Amounts of foreign currency derivative contracts                                                                                                      | 55,666        | 33,024        |
| Singapore dollar | Sell                                                                                                                                        |          |          |
| **Derivative [Line Items]**                                                                                                                                    |          |          |
| Notional Amounts of foreign currency derivative contracts                                                                                                      | 198           | 15            |
| Singapore dollar | Buy                                                                                                                                         |          |          |
| **Derivative [Line Items]**                                                                                                                                    |          |          |
| Notional Amounts of foreign currency derivative contracts                                                                                                      | 17,899        | 18,071        |
| Others | Sell                                                                                                                                                  |          |          |
| **Derivative [Line Items]**                                                                                                                                    |          |          |
| Notional Amounts of foreign currency derivative contracts                                                                                                      | 15,378        | 11,886        |
| Others | Buy                                                                                                                                                   |          |          |
| **Derivative [Line Items]**                                                                                                                                    |          |          |
| Notional Amounts of foreign currency derivative contracts                                                                                                      | $ 91,599      | $ 92,869      |

| X                                                                                                                                                                                                                                                                                                                                                                                                           |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.
+ References
No definition available.
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Nominal or face amount used to calculate payment on derivative.
+ References
Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 1B -URI http://asc.fasb.org/extlink&oid=125515794&loc=SL5580258-113959Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 1A -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=125515794&loc=SL5579245-113959
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| X                                                                                                                                                                  |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------|
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| X                                                                                                                                |
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| X                                                                                                                     |
|-----------------------------------------------------------------------------------------------------------------------|
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| X                                                                                                                     |
|-----------------------------------------------------------------------------------------------------------------------|
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| X                                                                                                                     |
|-----------------------------------------------------------------------------------------------------------------------|
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| X                                                                                                                     |
|-----------------------------------------------------------------------------------------------------------------------|
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| X                                                                                                                     |
|-----------------------------------------------------------------------------------------------------------------------|
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| X                                                                                                                     |
|-----------------------------------------------------------------------------------------------------------------------|
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| X                                                                                                                                 |
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