Debt - Guarantees (Details) - Ravenhall	Sep. 30, 2021 USD ($) Guarantee	Sep. 30, 2021 AUD ($) Guarantee
Debt Instrument [Line Items]
Number of letters of guarantee outstanding under separate international facilities relating to performance guarantees \| Guarantee	7	7
Letters of credit outstanding relating to performance guarantees \| $	$ 9,600,000
Letter of credit \| Revolver
Debt Instrument [Line Items]
Maximum exposure, undiscounted	$ 42,600,000	$ 59,000,000

Letters of credit outstanding relating to performance guarantees.

No definition available.

Name:	geo_LettersofCreditOutstandingRelatingtoPerformanceGuarantees
Namespace Prefix:	geo_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Number of letters of guarantee outstanding under separate international facilities relating to performance guarantees.

+ References

No definition available.

+ Details

Name:	geo_NumberOfLettersOfGuaranteeOutstandingUnderSeparateInternationalFacilitiesRelatingToPerformanceGuarantees
Namespace Prefix:	geo_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Maximum potential amount of future payments (undiscounted) the guarantor could be required to make under the guarantee or each group of similar guarantees before reduction for potential recoveries under recourse or collateralization provisions.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (b)(1)
-URI http://asc.fasb.org/extlink&oid=124440162&loc=d3e12069-110248

+ Details

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

- Details

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Namespace Prefix:
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- Details

Name:	us-gaap_CreditFacilityAxis=us-gaap_LetterOfCreditMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=geo_RevolverMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: