v2.4.0.6

Information for Financial Instruments on Which Fair Value Option was Elected (Detail) (USD $) | Jun. 30, 2012 | Dec. 31, 2011
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Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |  |
Uncollected principal balance on financial instruments that exceeded fair value total | $ (842,890) |  | $ (684,018) |
Fair value of financial instruments more than one day past due | 61,771 | [1] | 25,134 | [1]
Uncollected principal balance on financial instruments that exceeds fair value more than one day past due | (71,836) | [1] | (32,040) | [1]
Loans And Receivables |  |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |  |
Uncollected principal balance on financial instruments that exceeded fair value total | 1,738 |  | (162) |
Corporate Loans |  |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |  |
Uncollected principal balance on financial instruments that exceeded fair value total | (837,123) |  | (674,496) |
Fair value of financial instruments more than one day past due | 61,771 | [1] | 17,574 | [1]
Uncollected principal balance on financial instruments that exceeds fair value more than one day past due | (71,836) | [1] | (29,384) | [1]
Corporate Bonds |  |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |  |
Uncollected principal balance on financial instruments that exceeded fair value total | (7,505) |  | (9,360) |
Fair value of financial instruments more than one day past due |  |  | 7,560 | [1]
Uncollected principal balance on financial instruments that exceeds fair value more than one day past due |  |  | $ (2,656) | [1]
[1] | Past due Corporate Loans and Corporate Bonds within CLO assets are classified as past due if contractual payments are more than one day past due.

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- Definition Fair Value of Financial Instruments More Than One Day Past Due + References No definition available. + Details
Name: | bx_FairValueOfFinancialInstrumentsMoreThanOneDayPastDue
Namespace Prefix: | bx_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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- Definition Uncollected Principal Balance on Financial Instruments That Exceeded Fair Value Total + References No definition available. + Details
Name: | bx_UncollectedPrincipalBalanceOnFinancialInstrumentsThatExceededFairValueTotal
Namespace Prefix: | bx_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Uncollected Principal Balance On Financial Instruments That Exceeded Fair Value More than One Day Past Due + References No definition available. + Details
Name: | bx_UncollectedPrincipalBalanceOnFinancialInstrumentsThatExceedsFairValueMoreThanOneDayPastDue
Namespace Prefix: | bx_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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- Details
Name: | us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration