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v3.20.1

Employee Savings Plan (Details) - USD ($) | 12 Months Ended
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Apr. 30, 2020 | Apr. 30, 2019 | Apr. 30, 2018
Employee Savings Plan |  |  |
Amount of expense in contribution to the plan | $ 4,744,000 | $ 3,961,000 | $ 2,953,000

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- References No definition available. + Details
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Namespace Prefix: | us-gaap_
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Balance Type: | na
Period Type: | duration

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- Definition Amount of cost for defined contribution plan. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 70 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=49170846&loc=d3e28014-114942 + Details
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