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v3.21.2

Retirement Benefits - Additional Information (Detail) - USD ($) | 12 Months Ended
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Sep. 30, 2021 | Sep. 30, 2020
Retirement Benefits [Abstract] |  |
Retirement benefits expense under the provisions of the plan | $ 365,000 | $ 290,000

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- References No definition available. + Details
Name: | us-gaap_CompensationAndRetirementDisclosureAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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- Definition Amount of cost (reversal of cost) for pension and other postretirement benefits. + References No definition available. + Details
Name: | us-gaap_PensionAndOtherPostretirementBenefitExpense
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration