Debt Credit Facility Interest Rates (Details)	3 Months Ended
Mar. 31, 2013
Unused Letters of Credit
Line of Credit Facility [Line Items]
Debt Instrument, Interest Rate, Stated Percentage Rate Range, Minimum	2.00%
Debt Instrument, Interest Rate, Stated Percentage Rate Range, Maximum	3.00%
Unused Revolver
Line of Credit Facility [Line Items]
Debt Instrument, Interest Rate, Stated Percentage Rate Range, Minimum	0.375%
Debt Instrument, Interest Rate, Stated Percentage Rate Range, Maximum	0.50%
Minimum
Line of Credit Facility [Line Items]
Debt Instrument Interest Rate in Addition to Base Rate Borrowings	1.00%
Debt Instrument Interest Rate in Addition to Libor	2.00%
Maximum
Line of Credit Facility [Line Items]
Debt Instrument Interest Rate in Addition to Base Rate Borrowings	2.00%
Debt Instrument Interest Rate in Addition to Libor	3.00%

Debt instrument interest rate in addition to base rate borrowings.

No definition available.

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Namespace Prefix:	geo_
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Period Type:	duration

- Definition

Debt instrument interest rate in addition to LIBOR.

+ References

No definition available.

+ Details

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Namespace Prefix:	geo_
Data Type:	num:percentItemType
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Period Type:	duration

- Definition

When presenting a range of interest rates, the highest stated (contractual) rate for funds borrowed under the debt agreement as of the balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-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=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentageRateRangeMaximum
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

When presenting a range of interest rates, the lowest stated (contractual) rate for funds borrowed under the debt agreement as of the balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.22(a)(2))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentageRateRangeMinimum
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_LineOfCreditFacilityLineItems
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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration