v2.4.1.9

Summary of Impact of Derivative Financial Instruments to Condensed Consolidated Statements of Operations (Detail) (USD $) In Thousands, unless otherwise specified | 3 Months Ended
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Mar. 31, 2015 | Mar. 31, 2014
Derivative Financial Instruments [Line Items] |  |
Realized Gains (Losses) | $ 12,385 us-gaap_GainLossOnSaleOfDerivatives | $ 892 us-gaap_GainLossOnSaleOfDerivatives
Net Change in Unrealized Gain (Loss) | (26,942)us-gaap_UnrealizedGainLossOnDerivatives | (8,846)us-gaap_UnrealizedGainLossOnDerivatives
Net Investment Hedges | Foreign Currency Contracts |  |
Derivative Financial Instruments [Line Items] |  |
Hedge Ineffectiveness | 240 us-gaap_DerivativeNetHedgeIneffectivenessGainLoss / us-gaap_DerivativeInstrumentRiskAxis = us-gaap_ForeignExchangeContractMember / us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis = us-gaap_NetInvestmentHedgingMember |
Freestanding Derivatives | Foreign Currency Contracts |  |
Derivative Financial Instruments [Line Items] |  |
Realized Gains (Losses) | 14,073 us-gaap_GainLossOnSaleOfDerivatives / us-gaap_DerivativeInstrumentRiskAxis = us-gaap_ForeignExchangeContractMember / us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis = bx_FreestandingDerivativesMember | 1,439 us-gaap_GainLossOnSaleOfDerivatives / us-gaap_DerivativeInstrumentRiskAxis = us-gaap_ForeignExchangeContractMember / us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis = bx_FreestandingDerivativesMember
Net Change in Unrealized Gain (Loss) | (23,025)us-gaap_UnrealizedGainLossOnDerivatives / us-gaap_DerivativeInstrumentRiskAxis = us-gaap_ForeignExchangeContractMember / us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis = bx_FreestandingDerivativesMember | (8,117)us-gaap_UnrealizedGainLossOnDerivatives / us-gaap_DerivativeInstrumentRiskAxis = us-gaap_ForeignExchangeContractMember / us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis = bx_FreestandingDerivativesMember
Freestanding Derivatives | Interest Rate Contracts |  |
Derivative Financial Instruments [Line Items] |  |
Realized Gains (Losses) | (3,514)us-gaap_GainLossOnSaleOfDerivatives / us-gaap_DerivativeInstrumentRiskAxis = us-gaap_InterestRateContractMember / us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis = bx_FreestandingDerivativesMember | (833)us-gaap_GainLossOnSaleOfDerivatives / us-gaap_DerivativeInstrumentRiskAxis = us-gaap_InterestRateContractMember / us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis = bx_FreestandingDerivativesMember
Net Change in Unrealized Gain (Loss) | (995)us-gaap_UnrealizedGainLossOnDerivatives / us-gaap_DerivativeInstrumentRiskAxis = us-gaap_InterestRateContractMember / us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis = bx_FreestandingDerivativesMember | (2,542)us-gaap_UnrealizedGainLossOnDerivatives / us-gaap_DerivativeInstrumentRiskAxis = us-gaap_InterestRateContractMember / us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis = bx_FreestandingDerivativesMember
Freestanding Derivatives | Credit Default Swaps |  |
Derivative Financial Instruments [Line Items] |  |
Realized Gains (Losses) | 1,826 us-gaap_GainLossOnSaleOfDerivatives / us-gaap_DerivativeInstrumentRiskAxis = bx_CreditDefaultSwapsMember / us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis = bx_FreestandingDerivativesMember | 286 us-gaap_GainLossOnSaleOfDerivatives / us-gaap_DerivativeInstrumentRiskAxis = bx_CreditDefaultSwapsMember / us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis = bx_FreestandingDerivativesMember
Net Change in Unrealized Gain (Loss) | $ (2,922)us-gaap_UnrealizedGainLossOnDerivatives / us-gaap_DerivativeInstrumentRiskAxis = bx_CreditDefaultSwapsMember / us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis = bx_FreestandingDerivativesMember | $ 1,813 us-gaap_UnrealizedGainLossOnDerivatives / us-gaap_DerivativeInstrumentRiskAxis = bx_CreditDefaultSwapsMember / us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis = bx_FreestandingDerivativesMember

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- Definition Amount of gain (loss) from the ineffectiveness of the hedge. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4C -Subparagraph (d)(1) -URI http://asc.fasb.org/extlink&oid=35706170&loc=SL5624171-113959 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 25 -Section 50 -Paragraph 1 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=6886632&loc=d3e76258-113986 + Details
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- Definition The difference between the book value and the sale price of options, swaps, futures, forward contracts, and other derivative instruments. This element refers to the gain (loss) included in earnings. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 225 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-04.13(h)) -URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882 + Details
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- Definition The net change in the difference between the fair value and the carrying value, or in the comparative fair values, of derivative instruments, including options, swaps, futures, and forward contracts, held at each balance sheet date, that was included in earnings for the period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585 + Details
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