Change in interest rate on revolving loan facility

No definition available.

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Namespace Prefix:	ghl_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Increase or decrease in Revolving loan facility borrowing capacity based on agreeemnt modifications.

+ References

No definition available.

+ Details

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Namespace Prefix:	ghl_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	instant

- Definition

Debt Instrument, Alternative Interest Rate

+ References

No definition available.

+ Details

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Namespace Prefix:	ghl_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Line of Credit Facility, Weighted Average Interest Rate During Period.

+ References

No definition available.

+ Details

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Namespace Prefix:	ghl_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The reference rate for the variable rate of the debt instrument, such as LIBOR or the US Treasury rate and the maturity of the reference rate used, such as three months or six months LIBOR.

+ References

No definition available.

+ Details

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

- Definition

Average amount borrowed under the credit facility during the period.

+ References

No definition available.

+ Details

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

- Definition

Identification of whether the entity has been in compliance with any credit facility debt covenants during the period.

+ References

+ Details

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

- Definition

Amount of current borrowing capacity under the credit facility considering any current restrictions on the amount that could be borrowed (for example, borrowings may be limited by the amount of current assets), but without considering any amounts currently outstanding under the facility.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.19(b),22(b))

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

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 22

-Article 5

+ Details

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

- Definition

Date the credit facility terminates, in CCYY-MM-DD format.

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Description of the frequency of periodic payments, which may be presented in a variety of ways (for example, monthly, quarterly, annually).

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 129

-Paragraph 2, 4

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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 210.5-02.19(b),22(b))

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

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 22

-Article 5

+ Details

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

- Details

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Revolving Bank Loan Facility - Additional Information (Detail) (USD $) In Millions, unless otherwise specified		12 Months Ended
	Apr. 12, 2012	Dec. 31, 2012 Line of Credit [Member]	Dec. 31, 2011 Line of Credit [Member]	Dec. 31, 2010 Line of Credit [Member]
Line of Credit Facility [Line Items]
Revolving loan facility, borrowing capacity		$ 45.0
Change in Revolving loan facility borrowing capacity	5.0
Revolving loan facility, maturity date		Apr. 30, 2013
Change in interest rate on revolving loan facility	0.75%
Alternative interest rate (applies if higher than Prime Rate)		3.25%
Interest rate (applies if higher than alternative interest rate)		U.S. Prime Rate
Frequency of payments		Monthly
Weighted average daily borrowings outstanding under the loan facility		$ 28.4	$ 45.5
Weighted average interest rate		3.50%	4.00%	4.00%
Covenant compliance		The Company was compliant with all loan covenants.