v2.4.1.9
Summary of Quantitative Inputs and Assumptions for Items Categorized in Level III of Fair Value Hierarchy (Detail) (USD $)
In Thousands, unless otherwise specified
3 Months Ended 12 Months Ended
Mar. 31, 2015
Dec. 31, 2014
Fair Value, Option, Quantitative Disclosures [Line Items]    
Fair value assets 6,444,914us-gaap_AssetsFairValueDisclosure 6,760,099us-gaap_AssetsFairValueDisclosure
Fair value liabilities 6,933,747us-gaap_LiabilitiesFairValueDisclosure 6,797,104us-gaap_LiabilitiesFairValueDisclosure
Level 3    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Fair value assets 3,803,853us-gaap_AssetsFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
3,740,693us-gaap_AssetsFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
Discounted Cash Flows | Liabilities of Consolidated CLO Vehicles    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Default Rate 2.00%us-gaap_FairValueInputsProbabilityOfDefault
/ us-gaap_FairValueByLiabilityClassAxis
= bx_LiabilitiesOfConsolidatedCloVehiclesMember
/ us-gaap_ValuationTechniqueAxis
= bx_DiscountedCashFlowsMember
2.00%us-gaap_FairValueInputsProbabilityOfDefault
/ us-gaap_FairValueByLiabilityClassAxis
= bx_LiabilitiesOfConsolidatedCloVehiclesMember
/ us-gaap_ValuationTechniqueAxis
= bx_DiscountedCashFlowsMember
Recovery Lag 12 months 12 months
Pre-payment Rate 20.00%us-gaap_FairValueInputsPrepaymentRate
/ us-gaap_FairValueByLiabilityClassAxis
= bx_LiabilitiesOfConsolidatedCloVehiclesMember
/ us-gaap_ValuationTechniqueAxis
= bx_DiscountedCashFlowsMember
20.00%us-gaap_FairValueInputsPrepaymentRate
/ us-gaap_FairValueByLiabilityClassAxis
= bx_LiabilitiesOfConsolidatedCloVehiclesMember
/ us-gaap_ValuationTechniqueAxis
= bx_DiscountedCashFlowsMember
Discounted Cash Flows | Liabilities of Consolidated CLO Vehicles | Level 3    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Fair value liabilities 6,933,747us-gaap_LiabilitiesFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
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/ us-gaap_FairValueByLiabilityClassAxis
= bx_LiabilitiesOfConsolidatedCloVehiclesMember
/ us-gaap_ValuationTechniqueAxis
= bx_DiscountedCashFlowsMember
6,797,104us-gaap_LiabilitiesFairValueDisclosure
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/ us-gaap_FairValueByLiabilityClassAxis
= bx_LiabilitiesOfConsolidatedCloVehiclesMember
/ us-gaap_ValuationTechniqueAxis
= bx_DiscountedCashFlowsMember
Discounted Cash Flows | Liabilities of Consolidated CLO Vehicles | LIBOR    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Reinvestment Rate 4.00%bx_FairValueInputsReinvestmentRate
/ us-gaap_FairValueByLiabilityClassAxis
= bx_LiabilitiesOfConsolidatedCloVehiclesMember
/ us-gaap_ValuationTechniqueAxis
= bx_DiscountedCashFlowsMember
/ us-gaap_VariableRateAxis
= us-gaap_LondonInterbankOfferedRateLIBORMember
4.00%bx_FairValueInputsReinvestmentRate
/ us-gaap_FairValueByLiabilityClassAxis
= bx_LiabilitiesOfConsolidatedCloVehiclesMember
/ us-gaap_ValuationTechniqueAxis
= bx_DiscountedCashFlowsMember
/ us-gaap_VariableRateAxis
= us-gaap_LondonInterbankOfferedRateLIBORMember
Discounted Cash Flows | Weighted Average | Liabilities of Consolidated CLO Vehicles    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Discount Rate 2.90%us-gaap_FairValueInputsDiscountRate
/ us-gaap_FairValueByLiabilityClassAxis
= bx_LiabilitiesOfConsolidatedCloVehiclesMember
/ us-gaap_RangeAxis
= us-gaap_WeightedAverageMember
/ us-gaap_ValuationTechniqueAxis
= bx_DiscountedCashFlowsMember
[1] 2.30%us-gaap_FairValueInputsDiscountRate
/ us-gaap_FairValueByLiabilityClassAxis
= bx_LiabilitiesOfConsolidatedCloVehiclesMember
/ us-gaap_RangeAxis
= us-gaap_WeightedAverageMember
/ us-gaap_ValuationTechniqueAxis
= bx_DiscountedCashFlowsMember
[1]
Recovery Rate 66.00%bx_FairValueInputsRecoveryRate
/ us-gaap_FairValueByLiabilityClassAxis
= bx_LiabilitiesOfConsolidatedCloVehiclesMember
/ us-gaap_RangeAxis
= us-gaap_WeightedAverageMember
/ us-gaap_ValuationTechniqueAxis
= bx_DiscountedCashFlowsMember
[1] 66.00%bx_FairValueInputsRecoveryRate
/ us-gaap_FairValueByLiabilityClassAxis
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/ us-gaap_RangeAxis
= us-gaap_WeightedAverageMember
/ us-gaap_ValuationTechniqueAxis
= bx_DiscountedCashFlowsMember
[1]
Discounted Cash Flows | Minimum | Liabilities of Consolidated CLO Vehicles    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Discount Rate 0.60%us-gaap_FairValueInputsDiscountRate
/ us-gaap_FairValueByLiabilityClassAxis
= bx_LiabilitiesOfConsolidatedCloVehiclesMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
/ us-gaap_ValuationTechniqueAxis
= bx_DiscountedCashFlowsMember
0.30%us-gaap_FairValueInputsDiscountRate
/ us-gaap_FairValueByLiabilityClassAxis
= bx_LiabilitiesOfConsolidatedCloVehiclesMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
/ us-gaap_ValuationTechniqueAxis
= bx_DiscountedCashFlowsMember
Recovery Rate 30.00%bx_FairValueInputsRecoveryRate
/ us-gaap_FairValueByLiabilityClassAxis
= bx_LiabilitiesOfConsolidatedCloVehiclesMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
/ us-gaap_ValuationTechniqueAxis
= bx_DiscountedCashFlowsMember
30.00%bx_FairValueInputsRecoveryRate
/ us-gaap_FairValueByLiabilityClassAxis
= bx_LiabilitiesOfConsolidatedCloVehiclesMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
/ us-gaap_ValuationTechniqueAxis
= bx_DiscountedCashFlowsMember
Discounted Cash Flows | Maximum | Liabilities of Consolidated CLO Vehicles    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Discount Rate 29.00%us-gaap_FairValueInputsDiscountRate
/ us-gaap_FairValueByLiabilityClassAxis
= bx_LiabilitiesOfConsolidatedCloVehiclesMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
/ us-gaap_ValuationTechniqueAxis
= bx_DiscountedCashFlowsMember
19.30%us-gaap_FairValueInputsDiscountRate
/ us-gaap_FairValueByLiabilityClassAxis
= bx_LiabilitiesOfConsolidatedCloVehiclesMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
/ us-gaap_ValuationTechniqueAxis
= bx_DiscountedCashFlowsMember
Recovery Rate 70.00%bx_FairValueInputsRecoveryRate
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/ us-gaap_RangeAxis
= us-gaap_MaximumMember
/ us-gaap_ValuationTechniqueAxis
= bx_DiscountedCashFlowsMember
70.00%bx_FairValueInputsRecoveryRate
/ us-gaap_FairValueByLiabilityClassAxis
= bx_LiabilitiesOfConsolidatedCloVehiclesMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
/ us-gaap_ValuationTechniqueAxis
= bx_DiscountedCashFlowsMember
Blackstone's Treasury Cash Management Strategies | Discounted Cash Flows    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Default Rate 1.00%us-gaap_FairValueInputsProbabilityOfDefault
/ us-gaap_FairValueByAssetClassAxis
= bx_BlackstoneTreasuryCashManagementStrategiesMember
/ us-gaap_ValuationTechniqueAxis
= bx_DiscountedCashFlowsMember
 
Discount Rate   1.00%us-gaap_FairValueInputsDiscountRate
/ us-gaap_FairValueByAssetClassAxis
= bx_BlackstoneTreasuryCashManagementStrategiesMember
/ us-gaap_ValuationTechniqueAxis
= bx_DiscountedCashFlowsMember
Recovery Lag 12 months 12 months
Pre-payment Rate 30.00%us-gaap_FairValueInputsPrepaymentRate
/ us-gaap_FairValueByAssetClassAxis
= bx_BlackstoneTreasuryCashManagementStrategiesMember
/ us-gaap_ValuationTechniqueAxis
= bx_DiscountedCashFlowsMember
30.00%us-gaap_FairValueInputsPrepaymentRate
/ us-gaap_FairValueByAssetClassAxis
= bx_BlackstoneTreasuryCashManagementStrategiesMember
/ us-gaap_ValuationTechniqueAxis
= bx_DiscountedCashFlowsMember
Blackstone's Treasury Cash Management Strategies | Discounted Cash Flows | Level 3    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Fair value assets 28,238us-gaap_AssetsFairValueDisclosure
/ us-gaap_FairValueByAssetClassAxis
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/ us-gaap_FairValueByFairValueHierarchyLevelAxis
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26,167us-gaap_AssetsFairValueDisclosure
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= bx_DiscountedCashFlowsMember
Blackstone's Treasury Cash Management Strategies | Discounted Cash Flows | LIBOR    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Reinvestment Rate 4.50%bx_FairValueInputsReinvestmentRate
/ us-gaap_FairValueByAssetClassAxis
= bx_BlackstoneTreasuryCashManagementStrategiesMember
/ us-gaap_ValuationTechniqueAxis
= bx_DiscountedCashFlowsMember
/ us-gaap_VariableRateAxis
= us-gaap_LondonInterbankOfferedRateLIBORMember
4.50%bx_FairValueInputsReinvestmentRate
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= bx_BlackstoneTreasuryCashManagementStrategiesMember
/ us-gaap_ValuationTechniqueAxis
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/ us-gaap_VariableRateAxis
= us-gaap_LondonInterbankOfferedRateLIBORMember
Blackstone's Treasury Cash Management Strategies | Discounted Cash Flows | Weighted Average    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Discount Rate 6.80%us-gaap_FairValueInputsDiscountRate
/ us-gaap_FairValueByAssetClassAxis
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/ us-gaap_RangeAxis
= us-gaap_WeightedAverageMember
/ us-gaap_ValuationTechniqueAxis
= bx_DiscountedCashFlowsMember
[1] 7.20%us-gaap_FairValueInputsDiscountRate
/ us-gaap_FairValueByAssetClassAxis
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/ us-gaap_RangeAxis
= us-gaap_WeightedAverageMember
/ us-gaap_ValuationTechniqueAxis
= bx_DiscountedCashFlowsMember
[1]
Recovery Rate 66.00%bx_FairValueInputsRecoveryRate
/ us-gaap_FairValueByAssetClassAxis
= bx_BlackstoneTreasuryCashManagementStrategiesMember
/ us-gaap_RangeAxis
= us-gaap_WeightedAverageMember
/ us-gaap_ValuationTechniqueAxis
= bx_DiscountedCashFlowsMember
[1] 66.00%bx_FairValueInputsRecoveryRate
/ us-gaap_FairValueByAssetClassAxis
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/ us-gaap_RangeAxis
= us-gaap_WeightedAverageMember
/ us-gaap_ValuationTechniqueAxis
= bx_DiscountedCashFlowsMember
[1]
Blackstone's Treasury Cash Management Strategies | Discounted Cash Flows | Minimum    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Discount Rate 5.80%us-gaap_FairValueInputsDiscountRate
/ us-gaap_FairValueByAssetClassAxis
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/ us-gaap_RangeAxis
= us-gaap_MinimumMember
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= bx_DiscountedCashFlowsMember
5.80%us-gaap_FairValueInputsDiscountRate
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= bx_BlackstoneTreasuryCashManagementStrategiesMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
/ us-gaap_ValuationTechniqueAxis
= bx_DiscountedCashFlowsMember
Recovery Rate 30.00%bx_FairValueInputsRecoveryRate
/ us-gaap_FairValueByAssetClassAxis
= bx_BlackstoneTreasuryCashManagementStrategiesMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
/ us-gaap_ValuationTechniqueAxis
= bx_DiscountedCashFlowsMember
30.00%bx_FairValueInputsRecoveryRate
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/ us-gaap_RangeAxis
= us-gaap_MinimumMember
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= bx_DiscountedCashFlowsMember
Blackstone's Treasury Cash Management Strategies | Discounted Cash Flows | Maximum    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Discount Rate 10.20%us-gaap_FairValueInputsDiscountRate
/ us-gaap_FairValueByAssetClassAxis
= bx_BlackstoneTreasuryCashManagementStrategiesMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
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= bx_DiscountedCashFlowsMember
10.00%us-gaap_FairValueInputsDiscountRate
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= us-gaap_MaximumMember
/ us-gaap_ValuationTechniqueAxis
= bx_DiscountedCashFlowsMember
Recovery Rate 70.00%bx_FairValueInputsRecoveryRate
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= bx_BlackstoneTreasuryCashManagementStrategiesMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
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= bx_DiscountedCashFlowsMember
70.00%bx_FairValueInputsRecoveryRate
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= us-gaap_MaximumMember
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= bx_DiscountedCashFlowsMember
Blackstone's Treasury Cash Management Strategies | Net Asset Value Valuation Technique | Level 3    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Fair value assets 10,095us-gaap_AssetsFairValueDisclosure
/ us-gaap_FairValueByAssetClassAxis
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/ us-gaap_FairValueByFairValueHierarchyLevelAxis
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10,159us-gaap_AssetsFairValueDisclosure
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= bx_NetAssetValueValuationTechniqueMember
Blackstone's Treasury Cash Management Strategies | Transaction Price Valuation Technique | Level 3    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Fair value assets 3,141us-gaap_AssetsFairValueDisclosure
/ us-gaap_FairValueByAssetClassAxis
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4,470us-gaap_AssetsFairValueDisclosure
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= bx_TransactionPriceValuationTechniqueMember
Blackstone's Treasury Cash Management Strategies | Third Party Pricing Valuation Technique | Level 3    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Fair value assets 33,437us-gaap_AssetsFairValueDisclosure
/ us-gaap_FairValueByAssetClassAxis
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/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_ValuationTechniqueAxis
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54,257us-gaap_AssetsFairValueDisclosure
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= us-gaap_FairValueInputsLevel3Member
/ us-gaap_ValuationTechniqueAxis
= bx_ThirdPartyPricingValuationTechniqueMember
Loans And Receivables | Discounted Cash Flows | Level 3    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Fair value assets 19,878us-gaap_AssetsFairValueDisclosure
/ us-gaap_FairValueByAssetClassAxis
= bx_LoansAndReceivablesMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
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26,247us-gaap_AssetsFairValueDisclosure
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/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_ValuationTechniqueAxis
= bx_DiscountedCashFlowsMember
Loans And Receivables | Discounted Cash Flows | Weighted Average    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Discount Rate 17.30%us-gaap_FairValueInputsDiscountRate
/ us-gaap_FairValueByAssetClassAxis
= bx_LoansAndReceivablesMember
/ us-gaap_RangeAxis
= us-gaap_WeightedAverageMember
/ us-gaap_ValuationTechniqueAxis
= bx_DiscountedCashFlowsMember
[1] 10.90%us-gaap_FairValueInputsDiscountRate
/ us-gaap_FairValueByAssetClassAxis
= bx_LoansAndReceivablesMember
/ us-gaap_RangeAxis
= us-gaap_WeightedAverageMember
/ us-gaap_ValuationTechniqueAxis
= bx_DiscountedCashFlowsMember
[1]
Loans And Receivables | Discounted Cash Flows | Minimum    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Discount Rate 16.90%us-gaap_FairValueInputsDiscountRate
/ us-gaap_FairValueByAssetClassAxis
= bx_LoansAndReceivablesMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
/ us-gaap_ValuationTechniqueAxis
= bx_DiscountedCashFlowsMember
10.50%us-gaap_FairValueInputsDiscountRate
/ us-gaap_FairValueByAssetClassAxis
= bx_LoansAndReceivablesMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
/ us-gaap_ValuationTechniqueAxis
= bx_DiscountedCashFlowsMember
Loans And Receivables | Discounted Cash Flows | Maximum    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Discount Rate 17.40%us-gaap_FairValueInputsDiscountRate
/ us-gaap_FairValueByAssetClassAxis
= bx_LoansAndReceivablesMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
/ us-gaap_ValuationTechniqueAxis
= bx_DiscountedCashFlowsMember
12.20%us-gaap_FairValueInputsDiscountRate
/ us-gaap_FairValueByAssetClassAxis
= bx_LoansAndReceivablesMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
/ us-gaap_ValuationTechniqueAxis
= bx_DiscountedCashFlowsMember
Loans And Receivables | Transaction Price Valuation Technique | Level 3    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Fair value assets 20,813us-gaap_AssetsFairValueDisclosure
/ us-gaap_FairValueByAssetClassAxis
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/ us-gaap_FairValueByFairValueHierarchyLevelAxis
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14,150us-gaap_AssetsFairValueDisclosure
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= us-gaap_FairValueInputsLevel3Member
/ us-gaap_ValuationTechniqueAxis
= bx_TransactionPriceValuationTechniqueMember
Other | Discounted Cash Flows    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Default Rate 2.00%us-gaap_FairValueInputsProbabilityOfDefault
/ us-gaap_FairValueByAssetClassAxis
= bx_InvestmentAssetOtherMember
/ us-gaap_ValuationTechniqueAxis
= bx_DiscountedCashFlowsMember
2.00%us-gaap_FairValueInputsProbabilityOfDefault
/ us-gaap_FairValueByAssetClassAxis
= bx_InvestmentAssetOtherMember
/ us-gaap_ValuationTechniqueAxis
= bx_DiscountedCashFlowsMember
Recovery Lag 12 months 12 months
Pre-payment Rate 20.00%us-gaap_FairValueInputsPrepaymentRate
/ us-gaap_FairValueByAssetClassAxis
= bx_InvestmentAssetOtherMember
/ us-gaap_ValuationTechniqueAxis
= bx_DiscountedCashFlowsMember
20.00%us-gaap_FairValueInputsPrepaymentRate
/ us-gaap_FairValueByAssetClassAxis
= bx_InvestmentAssetOtherMember
/ us-gaap_ValuationTechniqueAxis
= bx_DiscountedCashFlowsMember
Other | Discounted Cash Flows | Level 3    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Fair value assets 82,370us-gaap_AssetsFairValueDisclosure
/ us-gaap_FairValueByAssetClassAxis
= bx_InvestmentAssetOtherMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_ValuationTechniqueAxis
= bx_DiscountedCashFlowsMember
92,604us-gaap_AssetsFairValueDisclosure
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/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_ValuationTechniqueAxis
= bx_DiscountedCashFlowsMember
Other | Discounted Cash Flows | LIBOR    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Reinvestment Rate 4.50%bx_FairValueInputsReinvestmentRate
/ us-gaap_FairValueByAssetClassAxis
= bx_InvestmentAssetOtherMember
/ us-gaap_ValuationTechniqueAxis
= bx_DiscountedCashFlowsMember
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4.00%bx_FairValueInputsReinvestmentRate
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/ us-gaap_ValuationTechniqueAxis
= bx_DiscountedCashFlowsMember
/ us-gaap_VariableRateAxis
= us-gaap_LondonInterbankOfferedRateLIBORMember
Other | Discounted Cash Flows | Weighted Average    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Discount Rate 3.30%us-gaap_FairValueInputsDiscountRate
/ us-gaap_FairValueByAssetClassAxis
= bx_InvestmentAssetOtherMember
/ us-gaap_RangeAxis
= us-gaap_WeightedAverageMember
/ us-gaap_ValuationTechniqueAxis
= bx_DiscountedCashFlowsMember
[1] 2.90%us-gaap_FairValueInputsDiscountRate
/ us-gaap_FairValueByAssetClassAxis
= bx_InvestmentAssetOtherMember
/ us-gaap_RangeAxis
= us-gaap_WeightedAverageMember
/ us-gaap_ValuationTechniqueAxis
= bx_DiscountedCashFlowsMember
[1]
Recovery Rate 66.00%bx_FairValueInputsRecoveryRate
/ us-gaap_FairValueByAssetClassAxis
= bx_InvestmentAssetOtherMember
/ us-gaap_RangeAxis
= us-gaap_WeightedAverageMember
/ us-gaap_ValuationTechniqueAxis
= bx_DiscountedCashFlowsMember
[1] 66.00%bx_FairValueInputsRecoveryRate
/ us-gaap_FairValueByAssetClassAxis
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/ us-gaap_RangeAxis
= us-gaap_WeightedAverageMember
/ us-gaap_ValuationTechniqueAxis
= bx_DiscountedCashFlowsMember
[1]
Other | Discounted Cash Flows | Minimum    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Discount Rate 1.60%us-gaap_FairValueInputsDiscountRate
/ us-gaap_FairValueByAssetClassAxis
= bx_InvestmentAssetOtherMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
/ us-gaap_ValuationTechniqueAxis
= bx_DiscountedCashFlowsMember
1.30%us-gaap_FairValueInputsDiscountRate
/ us-gaap_FairValueByAssetClassAxis
= bx_InvestmentAssetOtherMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
/ us-gaap_ValuationTechniqueAxis
= bx_DiscountedCashFlowsMember
Recovery Rate 30.00%bx_FairValueInputsRecoveryRate
/ us-gaap_FairValueByAssetClassAxis
= bx_InvestmentAssetOtherMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
/ us-gaap_ValuationTechniqueAxis
= bx_DiscountedCashFlowsMember
30.00%bx_FairValueInputsRecoveryRate
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Fair Value, Option, Quantitative Disclosures [Line Items]    
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Fair Value, Option, Quantitative Disclosures [Line Items]    
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Fair Value, Option, Quantitative Disclosures [Line Items]    
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Investments Of Consolidated Blackstone Funds | Level 3    
Fair Value, Option, Quantitative Disclosures [Line Items]    
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Fair Value, Option, Quantitative Disclosures [Line Items]    
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Fair Value, Option, Quantitative Disclosures [Line Items]    
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Investments Of Consolidated Blackstone Funds | Equity Securities | Discounted Cash Flows | Minimum    
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[1]
Investments Of Consolidated Blackstone Funds | Equity Securities | Market Comparable Companies | Minimum    
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Fair Value, Option, Quantitative Disclosures [Line Items]    
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Fair Value, Option, Quantitative Disclosures [Line Items]    
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Fair Value, Option, Quantitative Disclosures [Line Items]    
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Investments Of Consolidated Blackstone Funds | Partnership And LLC Interests | Discounted Cash Flows | Level 3    
Fair Value, Option, Quantitative Disclosures [Line Items]    
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Investments Of Consolidated Blackstone Funds | Partnership And LLC Interests | Discounted Cash Flows | Minimum    
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19.10%us-gaap_FairValueInputsCapRate
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Fair Value, Option, Quantitative Disclosures [Line Items]    
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Fair Value, Option, Quantitative Disclosures [Line Items]    
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Fair Value, Option, Quantitative Disclosures [Line Items]    
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Investments Of Consolidated Blackstone Funds | Debt Instruments | Discounted Cash Flows    
Fair Value, Option, Quantitative Disclosures [Line Items]    
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Recovery Lag   12 months
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Fair Value, Option, Quantitative Disclosures [Line Items]    
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Fair Value, Option, Quantitative Disclosures [Line Items]    
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[1] 16.10%us-gaap_FairValueInputsDiscountRate
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[1]
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[1] 9.30%us-gaap_FairValueInputsCapRate
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[1]
Recovery Rate   66.00%bx_FairValueInputsRecoveryRate
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[1]
Investments Of Consolidated Blackstone Funds | Debt Instruments | Discounted Cash Flows | Minimum    
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4.70%us-gaap_FairValueInputsLongTermRevenueGrowthRate
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1.00%us-gaap_FairValueInputsCapRate
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Fair Value, Option, Quantitative Disclosures [Line Items]    
Discount Rate 29.30%us-gaap_FairValueInputsDiscountRate
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24.70%us-gaap_FairValueInputsDiscountRate
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6.80%us-gaap_FairValueInputsLongTermRevenueGrowthRate
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11.3bx_FairValueInputsEarningsBeforeInterestTaxesDepreciationAndAmortizationExitMultiple
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12.40%us-gaap_FairValueInputsCapRate
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Investments Of Consolidated Blackstone Funds | Debt Instruments | Market Comparable Companies | Level 3    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Fair value assets 179us-gaap_AssetsFairValueDisclosure
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172us-gaap_AssetsFairValueDisclosure
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Investments Of Consolidated Blackstone Funds | Debt Instruments | Market Comparable Companies | Weighted Average    
Fair Value, Option, Quantitative Disclosures [Line Items]    
EBITDA Multiple 6.0us-gaap_FairValueInputsEarningsBeforeInterestTaxesDepreciationAndAmortizationMultiple
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[1] 6.6us-gaap_FairValueInputsEarningsBeforeInterestTaxesDepreciationAndAmortizationMultiple
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[1]
Investments Of Consolidated Blackstone Funds | Debt Instruments | Market Comparable Companies | Minimum    
Fair Value, Option, Quantitative Disclosures [Line Items]    
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6.6us-gaap_FairValueInputsEarningsBeforeInterestTaxesDepreciationAndAmortizationMultiple
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Investments Of Consolidated Blackstone Funds | Debt Instruments | Market Comparable Companies | Maximum    
Fair Value, Option, Quantitative Disclosures [Line Items]    
EBITDA Multiple 7.9us-gaap_FairValueInputsEarningsBeforeInterestTaxesDepreciationAndAmortizationMultiple
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7.9us-gaap_FairValueInputsEarningsBeforeInterestTaxesDepreciationAndAmortizationMultiple
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Investments Of Consolidated Blackstone Funds | Debt Instruments | Transaction Price Valuation Technique | Level 3    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Fair value assets 2,414us-gaap_AssetsFairValueDisclosure
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/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ dei_LegalEntityAxis
= bx_InvestmentsOfConsolidatedBlackstoneFundsMember
/ us-gaap_ValuationTechniqueAxis
= bx_TransactionPriceValuationTechniqueMember
686us-gaap_AssetsFairValueDisclosure
/ us-gaap_FairValueByAssetClassAxis
= bx_DebtInstrumentsMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ dei_LegalEntityAxis
= bx_InvestmentsOfConsolidatedBlackstoneFundsMember
/ us-gaap_ValuationTechniqueAxis
= bx_TransactionPriceValuationTechniqueMember
Investments Of Consolidated Blackstone Funds | Debt Instruments | Third Party Pricing Valuation Technique | Level 3    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Fair value assets 75,346us-gaap_AssetsFairValueDisclosure
/ us-gaap_FairValueByAssetClassAxis
= bx_DebtInstrumentsMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ dei_LegalEntityAxis
= bx_InvestmentsOfConsolidatedBlackstoneFundsMember
/ us-gaap_ValuationTechniqueAxis
= bx_ThirdPartyPricingValuationTechniqueMember
95,542us-gaap_AssetsFairValueDisclosure
/ us-gaap_FairValueByAssetClassAxis
= bx_DebtInstrumentsMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ dei_LegalEntityAxis
= bx_InvestmentsOfConsolidatedBlackstoneFundsMember
/ us-gaap_ValuationTechniqueAxis
= bx_ThirdPartyPricingValuationTechniqueMember
Investments Of Consolidated Blackstone Funds | Assets Of Consolidated CLO Vehicles | Discounted Cash Flows    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Discount Rate 3.80%us-gaap_FairValueInputsDiscountRate
/ us-gaap_FairValueByAssetClassAxis
= bx_AssetsOfConsolidatedCloVehiclesMember
/ dei_LegalEntityAxis
= bx_InvestmentsOfConsolidatedBlackstoneFundsMember
/ us-gaap_ValuationTechniqueAxis
= bx_DiscountedCashFlowsMember
8.00%us-gaap_FairValueInputsDiscountRate
/ us-gaap_FairValueByAssetClassAxis
= bx_AssetsOfConsolidatedCloVehiclesMember
/ dei_LegalEntityAxis
= bx_InvestmentsOfConsolidatedBlackstoneFundsMember
/ us-gaap_ValuationTechniqueAxis
= bx_DiscountedCashFlowsMember
Investments Of Consolidated Blackstone Funds | Assets Of Consolidated CLO Vehicles | Discounted Cash Flows | Level 3    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Fair value assets 1,926us-gaap_AssetsFairValueDisclosure
/ us-gaap_FairValueByAssetClassAxis
= bx_AssetsOfConsolidatedCloVehiclesMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ dei_LegalEntityAxis
= bx_InvestmentsOfConsolidatedBlackstoneFundsMember
/ us-gaap_ValuationTechniqueAxis
= bx_DiscountedCashFlowsMember
3,826us-gaap_AssetsFairValueDisclosure
/ us-gaap_FairValueByAssetClassAxis
= bx_AssetsOfConsolidatedCloVehiclesMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ dei_LegalEntityAxis
= bx_InvestmentsOfConsolidatedBlackstoneFundsMember
/ us-gaap_ValuationTechniqueAxis
= bx_DiscountedCashFlowsMember
Investments Of Consolidated Blackstone Funds | Assets Of Consolidated CLO Vehicles | Market Comparable Companies | Level 3    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Fair value assets 76,754us-gaap_AssetsFairValueDisclosure
/ us-gaap_FairValueByAssetClassAxis
= bx_AssetsOfConsolidatedCloVehiclesMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ dei_LegalEntityAxis
= bx_InvestmentsOfConsolidatedBlackstoneFundsMember
/ us-gaap_ValuationTechniqueAxis
= bx_MarketComparableCompaniesMember
290,658us-gaap_AssetsFairValueDisclosure
/ us-gaap_FairValueByAssetClassAxis
= bx_AssetsOfConsolidatedCloVehiclesMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ dei_LegalEntityAxis
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/ us-gaap_ValuationTechniqueAxis
= bx_MarketComparableCompaniesMember
Investments Of Consolidated Blackstone Funds | Assets Of Consolidated CLO Vehicles | Market Comparable Companies | Weighted Average    
Fair Value, Option, Quantitative Disclosures [Line Items]    
EBITDA Multiple 5.4us-gaap_FairValueInputsEarningsBeforeInterestTaxesDepreciationAndAmortizationMultiple
/ us-gaap_FairValueByAssetClassAxis
= bx_AssetsOfConsolidatedCloVehiclesMember
/ dei_LegalEntityAxis
= bx_InvestmentsOfConsolidatedBlackstoneFundsMember
/ us-gaap_RangeAxis
= us-gaap_WeightedAverageMember
/ us-gaap_ValuationTechniqueAxis
= bx_MarketComparableCompaniesMember
[1] 6.1us-gaap_FairValueInputsEarningsBeforeInterestTaxesDepreciationAndAmortizationMultiple
/ us-gaap_FairValueByAssetClassAxis
= bx_AssetsOfConsolidatedCloVehiclesMember
/ dei_LegalEntityAxis
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/ us-gaap_RangeAxis
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/ us-gaap_ValuationTechniqueAxis
= bx_MarketComparableCompaniesMember
[1]
Investments Of Consolidated Blackstone Funds | Assets Of Consolidated CLO Vehicles | Market Comparable Companies | Minimum    
Fair Value, Option, Quantitative Disclosures [Line Items]    
EBITDA Multiple 3.5us-gaap_FairValueInputsEarningsBeforeInterestTaxesDepreciationAndAmortizationMultiple
/ us-gaap_FairValueByAssetClassAxis
= bx_AssetsOfConsolidatedCloVehiclesMember
/ dei_LegalEntityAxis
= bx_InvestmentsOfConsolidatedBlackstoneFundsMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
/ us-gaap_ValuationTechniqueAxis
= bx_MarketComparableCompaniesMember
3.8us-gaap_FairValueInputsEarningsBeforeInterestTaxesDepreciationAndAmortizationMultiple
/ us-gaap_FairValueByAssetClassAxis
= bx_AssetsOfConsolidatedCloVehiclesMember
/ dei_LegalEntityAxis
= bx_InvestmentsOfConsolidatedBlackstoneFundsMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
/ us-gaap_ValuationTechniqueAxis
= bx_MarketComparableCompaniesMember
Investments Of Consolidated Blackstone Funds | Assets Of Consolidated CLO Vehicles | Market Comparable Companies | Maximum    
Fair Value, Option, Quantitative Disclosures [Line Items]    
EBITDA Multiple 7.5us-gaap_FairValueInputsEarningsBeforeInterestTaxesDepreciationAndAmortizationMultiple
/ us-gaap_FairValueByAssetClassAxis
= bx_AssetsOfConsolidatedCloVehiclesMember
/ dei_LegalEntityAxis
= bx_InvestmentsOfConsolidatedBlackstoneFundsMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
/ us-gaap_ValuationTechniqueAxis
= bx_MarketComparableCompaniesMember
15.0us-gaap_FairValueInputsEarningsBeforeInterestTaxesDepreciationAndAmortizationMultiple
/ us-gaap_FairValueByAssetClassAxis
= bx_AssetsOfConsolidatedCloVehiclesMember
/ dei_LegalEntityAxis
= bx_InvestmentsOfConsolidatedBlackstoneFundsMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
/ us-gaap_ValuationTechniqueAxis
= bx_MarketComparableCompaniesMember
Investments Of Consolidated Blackstone Funds | Assets Of Consolidated CLO Vehicles | Third Party Pricing Valuation Technique | Level 3    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Fair value assets 491,928us-gaap_AssetsFairValueDisclosure
/ us-gaap_FairValueByAssetClassAxis
= bx_AssetsOfConsolidatedCloVehiclesMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ dei_LegalEntityAxis
= bx_InvestmentsOfConsolidatedBlackstoneFundsMember
/ us-gaap_ValuationTechniqueAxis
= bx_ThirdPartyPricingValuationTechniqueMember
318,636us-gaap_AssetsFairValueDisclosure
/ us-gaap_FairValueByAssetClassAxis
= bx_AssetsOfConsolidatedCloVehiclesMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ dei_LegalEntityAxis
= bx_InvestmentsOfConsolidatedBlackstoneFundsMember
/ us-gaap_ValuationTechniqueAxis
= bx_ThirdPartyPricingValuationTechniqueMember
Investments Of Consolidated Blackstone Funds | Investment Funds | Net Asset Value Valuation Technique | Level 3    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Fair value assets 1,170,378us-gaap_AssetsFairValueDisclosure
/ us-gaap_FairValueByAssetClassAxis
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/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ dei_LegalEntityAxis
= bx_InvestmentsOfConsolidatedBlackstoneFundsMember
/ us-gaap_ValuationTechniqueAxis
= bx_NetAssetValueValuationTechniqueMember
1,103,210us-gaap_AssetsFairValueDisclosure
/ us-gaap_FairValueByAssetClassAxis
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/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ dei_LegalEntityAxis
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/ us-gaap_ValuationTechniqueAxis
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[1] Unobservable inputs were weighted based on the fair value of the investments included in the range.