v2.4.1.9
Related Party Transactions - Additional Information (Detail) (USD $)
3 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Dec. 31, 2014
Related Party Transaction [Line Items]      
Founder's, other senior managing directors' and employees' investments $ 1,000,000,000bx_InvestmentByFounderSeniorManagingDirectorsAndEmployees   $ 1,000,000,000bx_InvestmentByFounderSeniorManagingDirectorsAndEmployees
Founder's, other senior managing directors' and employees' share of the Net Income Attributable to Redeemable Non-Controlling Interests 53,100,000bx_FoundersOtherSeniorManagingDirectorsAndEmployeesShareOfNetIncomeAttributableToRedeemableNonControllingAndNonControllingInterestsInConsolidatedEntities 44,900,000bx_FoundersOtherSeniorManagingDirectorsAndEmployeesShareOfNetIncomeAttributableToRedeemableNonControllingAndNonControllingInterestsInConsolidatedEntities  
Management and Advisory Fees, Net from Affiliates 47,763,000us-gaap_RevenueFromRelatedParties 74,032,000us-gaap_RevenueFromRelatedParties  
Interest from loans to affiliates 2,000,000bx_InterestFromLoansToAffiliates 100,000bx_InterestFromLoansToAffiliates  
Partnership Unit to Blackstone Common Unit ratio 100.00%bx_LimitedPartnershipToCommonStockConversionRatio    
Cash saving in tax receivable agreements, percentage 85.00%bx_CashSavingInTaxReceivableAgreements    
Expected future payments under the tax receivable agreements 1,200,000,000bx_ExpectedFuturePaymentsUnderTaxReceivableAgreements    
Expected future payments under the tax receivable agreements in years 15 years    
After-tax net present value estimated payments $ 370,400,000bx_AfterTaxNetPresentValueEstimatedPaymentsForTaxReceivableAgreements    
After-tax net present value discount rate assumption 15.00%bx_AfterTaxNetPresentValueDiscountRateAssumptionForTaxReceivableAgreements