v2.4.0.8

Summary of Significant Accounting Policies - Additional Information (Detail) | 12 Months Ended
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Dec. 31, 2013
Summary Of Significant Accounting Policies [Line Items] |
Cash and cash equivalents maximum maturity term, months | 3 months
Finite-lived intangible assets, useful life, years | 7 years 4 months 24 days
Non-controlling interest, expiration period, minimum, years | 1 year
Non-controlling interest, expiration period, maximum, years | 3 years
Minimum |
Summary Of Significant Accounting Policies [Line Items] |
Finite-lived intangible assets, useful life, years | 3 years
Minimum | Leasehold Improvements |
Summary Of Significant Accounting Policies [Line Items] |
Property, plant and equipment, useful life, years | 10 years
Minimum | Other Long Lived Assets |
Summary Of Significant Accounting Policies [Line Items] |
Property, plant and equipment, useful life, years | 3 years
Maximum |
Summary Of Significant Accounting Policies [Line Items] |
Finite-lived intangible assets, useful life, years | 20 years
Maximum | Leasehold Improvements |
Summary Of Significant Accounting Policies [Line Items] |
Property, plant and equipment, useful life, years | 15 years
Maximum | Other Long Lived Assets |
Summary Of Significant Accounting Policies [Line Items] |
Property, plant and equipment, useful life, years | 7 years

X
- Definition Cash and Cash Equivalent Maturity Period Maximum + References No definition available. + Details
Name: | bx_CashAndCashEquivalentMaturityPeriodMaximum
Namespace Prefix: | bx_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Non Controlling Interest Expiration Period Maximum + References No definition available. + Details
Name: | bx_NonControllingInterestExpirationPeriodMaximum
Namespace Prefix: | bx_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Non Controlling Interest, Expiration Period, Minimum + References No definition available. + Details
Name: | bx_NonControllingInterestExpirationPeriodMinimum
Namespace Prefix: | bx_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

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

X
- Definition Useful life of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References No definition available. + Details
Name: | us-gaap_FiniteLivedIntangibleAssetUsefulLife
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment. + References No definition available. + Details
Name: | us-gaap_PropertyPlantAndEquipmentUsefulLife
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration