Lease receivables from customers net of reserves.

No definition available.

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

- Definition

Leases.

+ References

No definition available.

+ Details

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Period Type:	duration

- Definition

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

+ References

No definition available.

+ Details

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Namespace Prefix:	geos_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of assets held-for-sale that are not part of a disposal group, expected to be sold within a year or the normal operating cycle, if longer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 15
-Paragraph 4
-Subparagraph (b)(2)
-URI http://asc.fasb.org/extlink&oid=121558832&loc=d3e400-110220

+ Details

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

- 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=121576215&loc=SL77919396-209981

+ Details

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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=121576215&loc=SL77919359-209981

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	instant

- Definition

Term of lessor's sales-type lease, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

+ Details

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Namespace Prefix:	us-gaap_
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=121549951&loc=d3e39896-112707

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

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Balance Type:
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Leases - Additional Information (Details) $ in Thousands	3 Months Ended		6 Months Ended
Leases - Additional Information (Details) $ in Thousands	Mar. 31, 2021 USD ($) OperatingRightOfUseAsset	Mar. 31, 2020 USD ($)	Mar. 31, 2021 USD ($) OperatingRightOfUseAsset	Mar. 31, 2020 USD ($)	Sep. 30, 2020 USD ($)
Leases [Line Items]
Lease receivables from customers, net of reserves	$ 1,800		$ 1,800
Rental revenue	2,288	$ 16,390	4,026	$ 25,012
Future minimum lease payments to be received	7,100		7,100
Assets held for sale	$ 1,732		$ 1,732		$ 587
Sales type of lease term	6 months		6 months
Rental Equipment
Leases [Line Items]
Assets held for sale	$ 1,300		$ 1,300
Maximum
Leases [Line Items]
Lease term	6 months		6 months
Austin, Texas
Leases [Line Items]
Number of operating right-of use asset related to leased facility \| OperatingRightOfUseAsset	2		2