Debt instrument repurchase amount description.

No definition available.

Name:	geo_DebtInstrumentRepurchaseAmountDescription
Namespace Prefix:	geo_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1B
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123466505&loc=SL123495323-112611

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
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

Percentage of principal amount of debt redeemed.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentRedemptionPricePercentageOfPrincipalAmountRedeemed
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Fair value amount of debt instrument that was repurchased.

+ References

No definition available.

+ Details

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

- Definition

Face (par) amount of the original debt instrument that was repurchased.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentRepurchasedFaceAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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
-Topic 470
-SubTopic 50
-Section 40
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=123467658&loc=d3e12355-112629

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 50
-Section 40
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=123467658&loc=d3e12317-112629

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123570139&loc=d3e3602-108585

+ Details

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

- 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

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

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

- Details

Name:	us-gaap_DebtInstrumentAxis=geo_FivePointOneTwoFivePercentSeniorNotesDue2023Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=geo_FivePointEightSevenFivePercentSeniorNotesDue2022Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	us-gaap_DebtInstrumentAxis=geo_SixPercentSeniorNotesDue2026Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	us-gaap_DebtInstrumentAxis=geo_FivePointEightSevenFivePercentSeniorNotesDue2024Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_SeniorNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Debt (Debt Repurchases) (Details) - USD ($)	3 Months Ended	9 Months Ended		12 Months Ended
Debt (Debt Repurchases) (Details) - USD ($)	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2019	Dec. 31, 2020
Debt Instrument [Line Items]
Gain (loss) on extinguishment of debt	$ 1,472,000	$ 4,693,000	$ 3,035,000
5.125% Senior Notes due 2023
Debt Instrument [Line Items]
Stated interest rate		5.125%			5.125%
5.875% Senior Notes due 2022
Debt Instrument [Line Items]
Stated interest rate		5.875%			5.875%
Amended Credit Agreement
Debt Instrument [Line Items]
Maximum borrowing capacity		$ 100,000,000.0
Gain (loss) on extinguishment of debt				$ (1,200,000)
6.00% Senior Notes due 2026
Debt Instrument [Line Items]
Stated interest rate		6.00%			6.00%
Senior Notes and Term Loan
Debt Instrument [Line Items]
Debt instrument, repurchased face amount		On February 11, 2021, the Board authorized a new repurchase program for repurchases/retirements of the above referenced GEO Senior Notes and term loan, subject to certain limitations up to an aggregate maximum of $100.0 million through December 31, 2022.
5.875% Senior Notes due 2024
Debt Instrument [Line Items]
Stated interest rate		5.875%			5.875%
Senior Notes \| 5.125% Senior Notes due 2023
Debt Instrument [Line Items]
Stated interest rate	5.125%	5.125%	5.125%		5.125%
Debt instrument, repurchased face amount	$ 11,000,000.0	$ 22,500,000	$ 11,000,000.0
Percentage of principal amount redeemed		90.68%	75.66%
Repurchase amount	$ 8,300,000	$ 20,400,000	$ 8,300,000
Gain (loss) on extinguishment of debt		$ 4,700,000	$ 3,000,000.0
Senior Notes \| 5.875% Senior Notes due 2022
Debt Instrument [Line Items]
Stated interest rate		5.875%			5.875%
Senior Notes \| 6.00% Senior Notes due 2026
Debt Instrument [Line Items]
Stated interest rate		6.00%			6.00%
Senior Notes \| 5.875% Senior Notes due 2024
Debt Instrument [Line Items]
Stated interest rate	5.875%	5.875%	5.875%		5.875%
Debt instrument, repurchased face amount	$ 2,000,000.0	$ 17,200,000	$ 2,000,000.0
Percentage of principal amount redeemed		79.51%	76.75%
Repurchase amount	$ 1,500,000	$ 13,700,000	$ 1,500,000