Debt instrument agreement notice period.

No definition available.

Name:	geo_DebtInstrumentAgreementNoticePeriod
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Balance Type:	na
Period Type:	duration

- Definition

Debt Instrument, Covenant, Interest Coverage Ratio, Minimum

+ References

No definition available.

+ Details

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

- Definition

Debt Instrument, Covenant, Senior Secured Leverage Ratio, Maximum

+ References

No definition available.

+ Details

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Balance Type:	na
Period Type:	instant

- Definition

Debt Instrument, Covenant, Total Leverage Ratio, Maximum

+ References

No definition available.

+ Details

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Data Type:	xbrli:pureItemType
Balance Type:	na
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- Definition

Debt Instrument, Variable Rate, Floor

+ References

No definition available.

+ Details

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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Line Of Credit Facility, Accordion Feature, Increase Limit

+ References

No definition available.

+ Details

Name:	geo_LineOfCreditFacilityAccordionFeatureIncreaseLimit
Namespace Prefix:	geo_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Term loans.

+ References

No definition available.

+ Details

Name:	geo_TermLoans
Namespace Prefix:	geo_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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

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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount, before accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=119993939&loc=d3e28555-108399

+ Details

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

- Definition

The percentage points added to the reference rate to compute the variable rate on the interest rate derivative.

+ References

No definition available.

+ Details

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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Difference between the fair value of payments made and the carrying amount of debt which is extinguished prior to maturity.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 50
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+ Details

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

- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

+ References

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+ Details

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

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

+ Details

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

- Definition

Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

+ References

+ Details

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

- Definition

Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
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+ Details

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

- Definition

Weighted average interest rate of long-term debt outstanding calculated at point in time.

+ References

No definition available.

+ Details

Name:	us-gaap_LongtermDebtWeightedAverageInterestRate
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- Details

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Namespace Prefix:
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Balance Type:
Period Type:

- Details

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Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=geo_AdditionalRevolverMember
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Period Type:

- Details

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Balance Type:
Period Type:

- Details

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Period Type:

- Details

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Balance Type:
Period Type:

- Details

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Period Type:

- Details

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Period Type:

- Details

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- Details

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Debt (Amended Credit Agreement) (Details)		3 Months Ended		12 Months Ended
Debt (Amended Credit Agreement) (Details)	Jun. 12, 2019 USD ($)	Mar. 31, 2021 USD ($)	Mar. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Mar. 31, 2021 AUD ($)	Dec. 31, 2020 USD ($)	Jun. 12, 2019 AUD ($)	Feb. 14, 2018 USD ($)
Debt Instrument [Line Items]
Gain (loss) on extinguishment of debt		$ 3,038,000	$ 1,563,000
Amended Credit Agreement
Debt Instrument [Line Items]
Maximum borrowing capacity		100,000,000.0
Gain (loss) on extinguishment of debt				$ (1,200,000)
Debt issuance costs, gross	$ 4,700,000
Revolver
Debt Instrument [Line Items]
Revolver		631,600,000
Additional Revolver
Debt Instrument [Line Items]
Borrowing capacity remaining		209,000,000.0
Line of Credit
Debt Instrument [Line Items]
Revolver		631,605,000				$ 704,437,000
Term loan		$ 768,000,000				$ 770,000,000
Revolving Credit Facility \| Line of Credit \| Amended Credit Agreement
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 900,000,000.0							$ 900,000,000.0
Covenant, total leverage ratio, maximum	6.25						6.25
Senior secured leverage ratio	3.50						3.50
Interest coverage ratio	3.00						3.00
Weighted average interest rates on outstanding borrowings		2.57%			2.57%
Revolving Credit Facility \| Line of Credit \| Amended Credit Agreement \| LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate	2.25%						2.25%
Variable rate, floor	0.00%						0.00%
Term Loan
Debt Instrument [Line Items]
Term loan		$ 768,000,000.0
Term Loan \| Line of Credit \| Amended Credit Agreement
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 792,000,000.0
Term Loan \| Line of Credit \| Amended Credit Agreement \| LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate	2.00%						2.00%
Variable rate, floor	0.75%						0.75%
Letter of credit
Debt Instrument [Line Items]
Long-term debt		59,400,000
Letter of credit \| Line of Credit \| Amended Credit Agreement
Debt Instrument [Line Items]
Maximum borrowing capacity		196,000,000					$ 275,000,000
Long-term debt		0
Letter of credit \| Line of Credit \| Bank Guarantee And Standby Sub Facility
Debt Instrument [Line Items]
Maximum borrowing capacity		$ 44,100,000			$ 58,000,000
Debt instrument agreement notice period		90 days
Revolver					$ 58,000,000
Accordion \| Line of Credit \| Amended Credit Agreement
Debt Instrument [Line Items]
Accordion feature, increase limit	$ 450,000,000.0