v2.4.0.8

Employee Benefit Plans - Additional Information (Detail) (USD $) | 12 Months Ended
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Dec. 31, 2013 | Dec. 31, 2012 | Dec. 31, 2011
Defined Benefit Plan Disclosure [Line Items] |  |  |
Percentage of partnership contribution in professionals pre-tax annual compensation | 2.00% |  |
Annual maximum contribution professionals are able to receive from Plan Partnerships | $ 1,600 |  |
Additional percentage of partnership contribution in professionals pre-tax annual compensation | 50.00% |  |
401(k) Plan |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Expenses incurred by partnership in connection with employee benefit plan | 1,700,000 | 1,500,000 | 1,400,000
Defined Contribution Pension |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Expenses incurred by partnership in connection with employee benefit plan | $ 400,000 | $ 400,000 | $ 300,000

X
- Definition Additional percentage of partnership contribution in professional's annual compensation. + References No definition available. + Details
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Balance Type: | na
Period Type: | duration

X
- Definition Maximum amount professionals are eligible to recieve through Plan, Partnership contributions. + References No definition available. + Details
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Namespace Prefix: | bx_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
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X
- Definition Expenses incurred by a partnership in connection with employee benefit plan. + References No definition available. + Details
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Namespace Prefix: | bx_
Data Type: | xbrli:monetaryItemType
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X
- Definition Percentage of partnership contribution in professional's annual compensation. + References No definition available. + Details
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Namespace Prefix: | bx_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Details
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Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration