v2.4.1.9
Partnership's Borrowings Through Consolidated CLO Vehicles (Detail) (Partnership's Borrowings Through Consolidated CLO Vehicles, USD $)
In Thousands, unless otherwise specified
3 Months Ended 12 Months Ended
Mar. 31, 2015
Dec. 31, 2014
Debt Instrument [Line Items]    
Borrowing Outstanding $ 7,430,059us-gaap_DebtInstrumentCarryingAmount $ 7,334,316us-gaap_DebtInstrumentCarryingAmount
Senior Secured Notes
   
Debt Instrument [Line Items]    
Borrowing Outstanding 6,705,220us-gaap_DebtInstrumentCarryingAmount
/ us-gaap_InvestmentTypeAxis
= us-gaap_SeniorNotesMember
/ us-gaap_LongtermDebtTypeAxis
= bx_PartnershipBorrowingsThroughConsolidatedCollateralizedLoanObligationVehiclesMember
6,594,266us-gaap_DebtInstrumentCarryingAmount
/ us-gaap_InvestmentTypeAxis
= us-gaap_SeniorNotesMember
/ us-gaap_LongtermDebtTypeAxis
= bx_PartnershipBorrowingsThroughConsolidatedCollateralizedLoanObligationVehiclesMember
Weighted Average Interest Rate 1.52%us-gaap_DebtWeightedAverageInterestRate
/ us-gaap_InvestmentTypeAxis
= us-gaap_SeniorNotesMember
/ us-gaap_LongtermDebtTypeAxis
= bx_PartnershipBorrowingsThroughConsolidatedCollateralizedLoanObligationVehiclesMember
1.27%us-gaap_DebtWeightedAverageInterestRate
/ us-gaap_InvestmentTypeAxis
= us-gaap_SeniorNotesMember
/ us-gaap_LongtermDebtTypeAxis
= bx_PartnershipBorrowingsThroughConsolidatedCollateralizedLoanObligationVehiclesMember
Weighted Average Remaining Maturity in Years 3 years 3 months 18 days 3 years 9 months 18 days
Subordinated Notes
   
Debt Instrument [Line Items]    
Borrowing Outstanding $ 724,839us-gaap_DebtInstrumentCarryingAmount
/ us-gaap_InvestmentTypeAxis
= us-gaap_SeniorSubordinatedNotesMember
/ us-gaap_LongtermDebtTypeAxis
= bx_PartnershipBorrowingsThroughConsolidatedCollateralizedLoanObligationVehiclesMember
$ 740,050us-gaap_DebtInstrumentCarryingAmount
/ us-gaap_InvestmentTypeAxis
= us-gaap_SeniorSubordinatedNotesMember
/ us-gaap_LongtermDebtTypeAxis
= bx_PartnershipBorrowingsThroughConsolidatedCollateralizedLoanObligationVehiclesMember
Weighted Average Interest Rate    [1]    [1]
[1] The Subordinated Notes do not have contractual interest rates but instead receive distributions from the excess cash flows of the CLO vehicles.