Note 4 - Revenue Recognition - Contract Asset and Contract Liabilities (Details) $ in Thousands	12 Months Ended
Sep. 30, 2023 USD ($)
Balance as of September 30, 2022	$ 6,778
New performance obligations	17,006
Recognition of revenue as a result of satisfying performance obligations	(19,788)
Effect of exchange rate on deferred revenue	24
Balance as of September 30, 2023	4,020
Less: non-current portion	(551)
Current portion as of September 30, 2023	3,469
Customer Deposits [Member]
Balance as of September 30, 2022	4,724
New performance obligations	12,550
Recognition of revenue as a result of satisfying performance obligations	(16,510)
Effect of exchange rate on deferred revenue	2
Balance as of September 30, 2023	766
Less: non-current portion	0
Current portion as of September 30, 2023	766
Deferred Revenue [Member]
Balance as of September 30, 2022	2,054
New performance obligations	4,456
Recognition of revenue as a result of satisfying performance obligations	(3,278)
Effect of exchange rate on deferred revenue	22
Balance as of September 30, 2023	3,254
Less: non-current portion	(551)
Current portion as of September 30, 2023	$ 2,703

Represents effect of exchange rate for contract with customer liability.

No definition available.

Name:	gnss_ContractWithCustomerLiabilityEffectOfExchangeRate
Namespace Prefix:	gnss_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of increase in obligation to transfer good or service to customer for which consideration from customer has been received or is due, from new contract.

+ References

No definition available.

+ Details

Name:	gnss_ContractWithCustomerLiabilityIncreaseForNewContract
Namespace Prefix:	gnss_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of revenue recognized during period including amounts previously included in balance of obligation to transfer good or service to customer for which consideration from customer has been received or is due.

+ References

No definition available.

+ Details

Name:	gnss_ContractWithCustomerLiabilityRevenueRecognizedDuringPeriod
Namespace Prefix:	gnss_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of obligation to transfer good or service to customer for which consideration has been received or is receivable.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479837/606-10-45-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 8
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-8

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479837/606-10-45-2

+ Details

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

- Definition

Amount of obligation to transfer good or service to customer for which consideration has been received or is receivable, classified as current.

+ References

+ Details

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

- Definition

Amount of obligation to transfer good or service to customer for which consideration has been received or is receivable, classified as noncurrent.

+ References

+ Details

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

- Details

Name:	us-gaap_FairValueByLiabilityClassAxis=gnss_CustomerDepositsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByLiabilityClassAxis=gnss_DeferredRevenueMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: