v2.4.0.8

Derivative Financial Instruments - Additional Information (Detail) (USD $) In Millions, unless otherwise specified | 12 Months Ended
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Dec. 31, 2013
Derivative [Line Items] |
Net gain (loss) on hedged items | $ 64.2
Hedged gain (loss) remaining amortization period end date | Aug. 15, 2019

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- Definition Amortization Of Hedged Gain Loss Remaining Period End Date + References No definition available. + Details
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Namespace Prefix: | bx_
Data Type: | xbrli:dateItemType
Balance Type: | na
Period Type: | instant

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

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- Definition Total amount of gain (loss) derived from fair value hedges recognized in earnings in the period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4C -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5624171-113959 + Details
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Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration