Name:	genc_CostBasisReductionInInventoryPercentage
Namespace Prefix:	genc_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

Inventory cost basis determination period maximum.

No definition available.

Name:	genc_InventoryCostBasisDeterminationPeriodMaximum
Namespace Prefix:	genc_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Inventory cost basis determination period minimum.

No definition available.

Name:	genc_InventoryCostBasisDeterminationPeriodMinimum
Namespace Prefix:	genc_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Represents the inventory valuation estimate amount after accounting for inventories related to obsolescence, excessive levels, deterioration, possible alternative uses and other factors in determining net realizable value. Inventories are valued at the lower of cost or market, with cost being determined principally by using the last-in, first-out (LIFO) method and market defined as replacement cost for raw materials and net realizable value for work in process and finished goods. Appropriate consideration is given to obsolescence, excessive levels, deterioration, possible alternative uses and other factors in determining net realizable value. The cost of work in process and finished goods includes materials, direct labor, variable costs and overhead. The Company evaluates the need to record inventory adjustments on all inventories, including raw material, work in process, finished goods, spare parts and used equipment. Used equipment acquired by the Company on trade-in from customers i

No definition available.

Name:	genc_InventoryValuationEstimate
Namespace Prefix:	genc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Amount by which inventory stated at last-in first-out (LIFO) is less than (in excess of) inventory stated at other inventory cost methods.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(6)(c))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1

Name:	us-gaap_InventoryLIFOReserve
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

The change in the inventory reserve representing the cumulative difference in cost between the first in, first out and the last in, first out inventory valuation methods, which change has been reflected in the statement of income during the period.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 330
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 5.L)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480581/330-10-S99-1

Name:	us-gaap_InventoryLIFOReservePeriodCharge
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

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.

No definition available.