Leases - Additional Information (Details) $ in Thousands	12 Months Ended
Sep. 30, 2021 USD ($) OperatingRightOfUseAsset	Sep. 30, 2020 USD ($)
Leases [Line Items]
Trade accounts receivables included lease receivables	$ 7,500
Rental revenue	19,000	$ 53,699
Future minimum lease payments to be received	800
Rental equipment depreciation expense	$ 15,075	$ 17,945
Maximum
Leases [Line Items]
Lease term	6 months
Austin, Texas
Leases [Line Items]
Number of operating right-of use asset related to leased facility \| OperatingRightOfUseAsset	2

Leases.

No definition available.

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Namespace Prefix:	geos_
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- Definition

Number of operating right-of use asset related to leased facility.

+ References

No definition available.

+ Details

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- Definition

Trade accounts receivables included lease receivables.

+ References

No definition available.

+ Details

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Namespace Prefix:	geos_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

This element represents equipment expense including depreciation, repairs, rentals, and service contract costs. This item also includes equipment purchases which do not qualify for capitalization in accordance with the entity's accounting policy. This item may also include furniture expenses.

+ References

No definition available.

+ Details

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

- Definition

Amount of lease payments to be received by lessor for operating lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 30
-Section 50
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=124258985&loc=SL77919396-209981

+ Details

Name:	us-gaap_LessorOperatingLeasePaymentsToBeReceived
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Term of lessor'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 30
-Section 50
-Paragraph 3
-Subparagraph (a)(3)
-URI http://asc.fasb.org/extlink&oid=124258985&loc=SL77919359-209981

+ Details

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Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	instant

- Definition

The total amount of revenue recognized for the period from operating leases, including minimum lease revenue, contingent revenue, percentage revenue and sublease revenue.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 20
-Section 25
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=123415192&loc=d3e39896-112707

+ Details

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Balance Type:	credit
Period Type:	duration

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- Details

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