v2.4.0.8

Commitments and Contingencies - Additional Information (Detail) (USD $) | 12 Months Ended
--- | ---
Dec. 31, 2013 | Dec. 31, 2012 | Dec. 31, 2011
Schedule Of Commitments And Contingencies [Line Items] |  |  |
Rent expense | $ 78,600,000 | $ 74,800,000 | $ 72,700,000
Leases | 9,000,000 | 9,400,000 |
General partner capital funding | 1,500,000,000 |  |
Total investments at risk in respect of guarantees extended | 4,900,000 |  |
Loans held By employees for investment guaranteed | 60,300,000 |  |
Contingent obligations currently anticipated to expire end | 2018 |  |
Cash clawback obligation | 89,700,000 |  |
Provision for cash clawback | 420,900,000 |  |
Blackstone Holdings Finance Co. L.L.C. |  |  |
Schedule Of Commitments And Contingencies [Line Items] |  |  |
Cash clawback obligation | 70,600,000 |  |
Current And Former Blackstone Personnel |  |  |
Schedule Of Commitments And Contingencies [Line Items] |  |  |
Cash clawback obligation | 19,100,000 |  |
Blackstone Funds |  |  |
Schedule Of Commitments And Contingencies [Line Items] |  |  |
Funds signed investment commitments | 54,600,000 |  |
Blackstone Funds | Portfolio Company Acquisition |  |  |
Schedule Of Commitments And Contingencies [Line Items] |  |  |
Signed investment commitments for portfolio company acquisitions in process of closing | $ 25,200,000 |  |
Maximum |  |  |
Schedule Of Commitments And Contingencies [Line Items] |  |  |
Operating lease expiration year | 2032 |  |

X
- Definition Contingent obligations currently anticipated to expire end + References No definition available. + Details
Name: | bx_ContingentObligationsCurrentlyAnticipatedToExpireEnd
Namespace Prefix: | bx_
Data Type: | xbrli:gYearItemType
Balance Type: | na
Period Type: | duration

X
- Definition Funds Signed Investment Commitments + References No definition available. + Details
Name: | bx_FundsSignedInvestmentCommitments
Namespace Prefix: | bx_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition General Partner Capital Funding Commitments + References No definition available. + Details
Name: | bx_GeneralPartnerCapitalFundingCommitments
Namespace Prefix: | bx_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Leases with security. + References No definition available. + Details
Name: | bx_LeasesWithSecurity
Namespace Prefix: | bx_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Loans Held By Employees For Investment Guaranteed + References No definition available. + Details
Name: | bx_LoansHeldByEmployeesForInvestmentGuaranteed
Namespace Prefix: | bx_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Operating Lease Expiration Year + References No definition available. + Details
Name: | bx_OperatingLeaseExpirationYear
Namespace Prefix: | bx_
Data Type: | xbrli:gYearItemType
Balance Type: | na
Period Type: | duration

X
- Definition Payment Of Cash Clawback Obligation + References No definition available. + Details
Name: | bx_PaymentOfCashClawbackObligation
Namespace Prefix: | bx_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Provision for cash clawback + References No definition available. + Details
Name: | bx_ProvisionForCashClawback
Namespace Prefix: | bx_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | bx_ScheduleOfCommitmentsAndContingenciesLineItems
Namespace Prefix: | bx_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Signed Investment Commitments For Portfolio Company Acquisitions In Process Of Closing + References No definition available. + Details
Name: | bx_SignedInvestmentCommitmentsForPortfolioCompanyAcquisitionsInProcessOfClosing
Namespace Prefix: | bx_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition This item represents disclosure of all significant concentrations of credit risk or market risk arising from the subject financial instrument (as defined), whether from an individual counterparty or groups of counterparties. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Available-for-Sale Securities -URI http://asc.fasb.org/extlink&oid=6505594 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Trading Securities -URI http://asc.fasb.org/extlink&oid=6526789 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 25 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=28360136&loc=d3e22054-111558 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 1 -Subparagraph a, f, g -Article 7 + Details
Name: | us-gaap_FairValueConcentrationOfRiskInvestments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Rental expense for the reporting period incurred under operating leases, including minimum and any contingent rent expense, net of related sublease income. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 840 -SubTopic 20 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6453985&loc=d3e41499-112717 + Details
Name: | us-gaap_OperatingLeasesRentExpenseNet
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration