2.4.0.82404403 - Disclosure - Investments - Carrying Value of Investments in Merchant Banking Funds (Details)truefalseIn Thousands, unless otherwise specifiedfalse1false USDfalsefalse$I2013Q2http://www.sec.gov/CIK0001282977instant2013-06-30T00:00:000001-01-01T00:00:00usdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$2false USDfalsefalse$I2012Q4http://www.sec.gov/CIK0001282977instant2012-12-31T00:00:000001-01-01T00:00:00usdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$1true 3us-gaap_InvestmentsInAndAdvancesToAffiliatesLineItemsus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Investments in and Advances to Affiliates [Line Items]2false 4us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVenturesus-gaap_truedebitinstantfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truefalsefalse1299700012997USD$falsetruefalse2truefalsefalse1677200016772USD$falsetruefalsexbrli:monetaryItemTypemonetaryTotal investments in (A) an entity in which the entity has significant influence, but does not have control, (B) subsidiaries that are not required to be consolidated and are accounted for using the equity and or cost method, and (C) an entity in which the reporting entity shares control of the entity with another party or group. Includes long-term advances receivable from a party that is affiliated with the reporting entity by means of direct or indirect ownership.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.12) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 false2Investments in merchant banking funds3false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3false USDtruefalse$I2013Q2_us-gaap_InvestmentsInAndAdvancesToAffiliatesCategorizationAxis_ghl_GcpIiMemberhttp://www.sec.gov/CIK0001282977instant2013-06-30T00:00:000001-01-01T00:00:00falsefalseGCP II [Member]us-gaap_InvestmentsInAndAdvancesToAffiliatesCategorizationAxisxbrldihttp://xbrl.org/2006/xbrldighl_GcpIiMemberus-gaap_InvestmentsInAndAdvancesToAffiliatesCategorizationAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$nanafalse0GCP II [Member]4true 3us-gaap_InvestmentsInAndAdvancesToAffiliatesLineItemsus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Investments in and Advances to Affiliates [Line Items]5false 4us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVenturesus-gaap_truedebitinstantfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truefalsefalse75160007516USD$falsefalsefalse2truefalsefalse1117300011173USD$falsefalsefalsexbrli:monetaryItemTypemonetaryTotal investments in (A) an entity in which the entity has significant influence, but does not have control, (B) subsidiaries that are not required to be consolidated and are accounted for using the equity and or cost method, and (C) an entity in which the reporting entity shares control of the entity with another party or group. Includes long-term advances receivable from a party that is affiliated with the reporting entity by means of direct or indirect ownership.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.12) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 false2Investments in merchant banking funds6false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse5false USDtruefalse$I2013Q2_us-gaap_InvestmentsInAndAdvancesToAffiliatesCategorizationAxis_ghl_GcpIiiMemberhttp://www.sec.gov/CIK0001282977instant2013-06-30T00:00:000001-01-01T00:00:00falsefalseGCP III [Member]us-gaap_InvestmentsInAndAdvancesToAffiliatesCategorizationAxisxbrldihttp://xbrl.org/2006/xbrldighl_GcpIiiMemberus-gaap_InvestmentsInAndAdvancesToAffiliatesCategorizationAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$nanafalse0GCP III [Member]7true 3us-gaap_InvestmentsInAndAdvancesToAffiliatesLineItemsus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Investments in and Advances to Affiliates [Line Items]8false 4us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVenturesus-gaap_truedebitinstantfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truefalsefalse20250002025USD$falsefalsefalse2truefalsefalse13670001367USD$falsefalsefalsexbrli:monetaryItemTypemonetaryTotal investments in (A) an entity in which the entity has significant influence, but does not have control, (B) subsidiaries that are not required to be consolidated and are accounted for using the equity and or cost method, and (C) an entity in which the reporting entity shares control of the entity with another party or group. Includes long-term advances receivable from a party that is affiliated with the reporting entity by means of direct or indirect ownership.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.12) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 false2Investments in merchant banking funds9false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse7false USDtruefalse$I2013Q2_us-gaap_InvestmentsInAndAdvancesToAffiliatesCategorizationAxis_ghl_GcpIMemberhttp://www.sec.gov/CIK0001282977instant2013-06-30T00:00:000001-01-01T00:00:00falsefalseGCP I [Member]us-gaap_InvestmentsInAndAdvancesToAffiliatesCategorizationAxisxbrldihttp://xbrl.org/2006/xbrldighl_GcpIMemberus-gaap_InvestmentsInAndAdvancesToAffiliatesCategorizationAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$nanafalse0GCP I [Member]10true 3us-gaap_InvestmentsInAndAdvancesToAffiliatesLineItemsus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Investments in and Advances to Affiliates [Line Items]11false 4us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVenturesus-gaap_truedebitinstantfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truefalsefalse15870001587USD$falsefalsefalse2truefalsefalse22470002247USD$falsefalsefalsexbrli:monetaryItemTypemonetaryTotal investments in (A) an entity in which the entity has significant influence, but does not have control, (B) subsidiaries that are not required to be consolidated and are accounted for using the equity and or cost method, and (C) an entity in which the reporting entity shares control of the entity with another party or group. Includes long-term advances receivable from a party that is affiliated with the reporting entity by means of direct or indirect ownership.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.12) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 false2Investments in merchant banking funds12false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse9false USDtruefalse$I2013Q2_us-gaap_InvestmentsInAndAdvancesToAffiliatesCategorizationAxis_us-gaap_OtherAffiliatesMemberhttp://www.sec.gov/CIK0001282977instant2013-06-30T00:00:000001-01-01T00:00:00falsefalseOther Merchant Banking Fundsus-gaap_InvestmentsInAndAdvancesToAffiliatesCategorizationAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_OtherAffiliatesMemberus-gaap_InvestmentsInAndAdvancesToAffiliatesCategorizationAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$nanafalse0Other Merchant Banking Funds13true 3us-gaap_InvestmentsInAndAdvancesToAffiliatesLineItemsus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Investments in and Advances to Affiliates [Line Items]14false 4us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVenturesus-gaap_truedebitinstantfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truefalsefalse18690001869USD$falsetruefalse2truefalsefalse19850001985USD$falsetruefalsexbrli:monetaryItemTypemonetaryTotal investments in (A) an entity in which the entity has significant influence, but does not have control, (B) subsidiaries that are not required to be consolidated and are accounted for using the equity and or cost method, and (C) an entity in which the reporting entity shares control of the entity with another party or group. Includes long-term advances receivable from a party that is affiliated with the reporting entity by means of direct or indirect ownership.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 210.5-02.12) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 false2Investments in merchant banking fundsfalseInvestments - Carrying Value of Investments in Merchant Banking Funds (Details) (USD $)ThousandsUnKnownUnKnownUnKnowntruefalsefalseSheethttp://www.greenhill.com/role/InvestmentsCarryingValueOfInvestmentsInMerchantBankingFundsDetails214