Note 4 - Revenue Recognition - Contract Asset and Contract Liabilities (Details) - USD ($) $ in Thousands	6 Months Ended
Mar. 31, 2023	Sep. 30, 2022
Balance as of September 30, 2022	$ 6,778
New performance obligations	6,046
Recognition of revenue as a result of satisfying performance obligations	(9,190)
Effect of exchange rate on deferred revenue	32
Balance as of March 31, 2023	3,666
Less: non-current portion	(159)	$ (227)
Current portion as of March 31, 2023	3,507
Customer Deposits [Member]
Balance as of September 30, 2022	4,724
New performance obligations	4,831
Recognition of revenue as a result of satisfying performance obligations	(7,701)
Effect of exchange rate on deferred revenue	1
Balance as of March 31, 2023	1,855
Less: non-current portion	0
Current portion as of March 31, 2023	1,855
Deferred Revenue [Member]
Balance as of September 30, 2022	2,054
New performance obligations	1,215
Recognition of revenue as a result of satisfying performance obligations	(1,489)
Effect of exchange rate on deferred revenue	31
Balance as of March 31, 2023	1,811
Less: non-current portion	(159)
Current portion as of March 31, 2023	$ 1,652

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: