XML 59 R46.htm IDEA: XBRL DOCUMENT
v3.20.4

Retirement Benefits - Additional Information (Detail) - USD ($) | 12 Months Ended
--- | ---
Sep. 30, 2020 | Sep. 30, 2019
Retirement Benefits [Abstract] |  |
Retirement benefits expense under the provisions of the plan | $ 290,000 | $ 282,000

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

X
- 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