Note 4 - Revenue Recognition - Contract Asset and Contract Liabilities (Details) - USD ($)	6 Months Ended
Mar. 31, 2020	Sep. 30, 2019
Balance	$ 6,122,498
New performance obligations	2,587,824
Recognition of revenue as a result of satisfying performance obligations	(4,550,007)
Effect of exchange rate on deferred revenue	5,523
Balance	4,165,838
Less: non-current portion	(435,880)
Current portion	3,729,958
Customer Deposits [Member]
Balance	5,063,091
New performance obligations	2,302,269
Recognition of revenue as a result of satisfying performance obligations	(4,099,364)
Effect of exchange rate on deferred revenue
Balance	3,265,996
Less: non-current portion
Current portion	3,265,996	$ 5,063,091
Deferred Revenue [Member]
Balance	1,059,407
New performance obligations	285,555
Recognition of revenue as a result of satisfying performance obligations	(450,643)
Effect of exchange rate on deferred revenue	5,523
Balance	899,842
Less: non-current portion	(435,880)	(550,885)
Current portion	$ 463,962	$ 508,522

Represents effect of exchange rate for contract with customer liability.

No definition available.

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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

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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
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=121556615&loc=SL49130531-203044

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
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-URI http://asc.fasb.org/extlink&oid=121556615&loc=SL49130532-203044

+ Details

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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

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=121556615&loc=SL49130531-203044

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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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

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
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-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=121556615&loc=SL49130532-203044

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-URI http://asc.fasb.org/extlink&oid=121556615&loc=SL49130531-203044

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130549-203045

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of revenue recognized that was 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

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 8
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130549-203045

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

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Namespace Prefix:
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Balance Type:
Period Type:

- Details

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Period Type: