XML 63 R50.htm IDEA: XBRL DOCUMENT
v3.20.4

Leases - Additional Information (Detail) - USD ($) |  | 12 Months Ended
--- | --- | ---
Aug. 28, 2020 | Sep. 30, 2020 | Sep. 30, 2019
Lessee, Lease, Description [Line Items] |  |  |
Total rental expense |  | $ 37,000 | $ 40,000
Assets | $ 970,000 |  |
Operating Lease, Expense |  | 28,000 |
Operating lease term | 3 years |  |
New Lease Agreement [Member] |  |  |
Lessee, Lease, Description [Line Items] |  |  |
Assets |  | 970,000 |
Blaw Knox Product Line From Volvo CE [Member] | New Lease Agreement [Member] |  |  |
Lessee, Lease, Description [Line Items] |  |  |
Assets |  | $ 942,000 |
Operating lease liability date of expiry | Aug. 31, 2023 |  |

X
- Definition Date of expiry of operating lease. + References No definition available. + Details
Name: | genc_DateOfExpiryOfOperatingLease
Namespace Prefix: | genc_
Data Type: | xbrli:dateItemType
Balance Type: | na
Period Type: | duration

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. + Details
Name: | us-gaap_LesseeLeaseDescriptionLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Term of lessee's operating lease, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 50 -Paragraph 3 -Subparagraph (a)(3) -URI http://asc.fasb.org/extlink&oid=121609121&loc=SL77918673-209980 + Details
Name: | us-gaap_LesseeOperatingLeaseTermOfContract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | instant

X
- Definition Amount of operating lease expense. Excludes sublease income. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 45 -Paragraph 4 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=121603541&loc=SL77918638-209977 + Details
Name: | us-gaap_OperatingLeaseExpense
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of lessee's right to use underlying asset under operating lease. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 45 -Paragraph 1 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=121603541&loc=SL77918627-209977 + Details
Name: | us-gaap_OperatingLeaseRightOfUseAsset
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Rental expense for the reporting period incurred under operating leases, including minimum and any contingent rent expense, net of related sublease income. + References Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef -Publisher FASB -Name Accounting Standards Codification -Topic 840 -SubTopic 20 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=121573735&loc=d3e41499-112717 + Details
Name: | us-gaap_OperatingLeasesRentExpenseNet
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | us-gaap_LeaseContractualTermAxis=genc_NewLeaseAgreementMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_BusinessAcquisitionAxis=genc_BlawKnoxProductLineFromVolvoCeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |