v2.4.1.9

Summary of Status of Partnership's Unvested Equity-Based Awards (Detail) (USD $)	3 Months Ended
	Mar. 31, 2015
Blackstone | Blackstone Partnership Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Beginning Balance	33,498,237us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber / us-gaap_AwardTypeAxis = bx_BlackstonePartnershipUnitsMember / dei_LegalEntityAxis = us-gaap_ParentCompanyMember
Granted (Units)	19,874,298us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod / us-gaap_AwardTypeAxis = bx_BlackstonePartnershipUnitsMember / dei_LegalEntityAxis = us-gaap_ParentCompanyMember
Vested (Units)	(1,697,202)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod / us-gaap_AwardTypeAxis = bx_BlackstonePartnershipUnitsMember / dei_LegalEntityAxis = us-gaap_ParentCompanyMember
Forfeited (Units)	43,916us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod / us-gaap_AwardTypeAxis = bx_BlackstonePartnershipUnitsMember / dei_LegalEntityAxis = us-gaap_ParentCompanyMember
Ending Balance	51,719,249us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber / us-gaap_AwardTypeAxis = bx_BlackstonePartnershipUnitsMember / dei_LegalEntityAxis = us-gaap_ParentCompanyMember
Beginning Balance	$ 26.19us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue / us-gaap_AwardTypeAxis = bx_BlackstonePartnershipUnitsMember / dei_LegalEntityAxis = us-gaap_ParentCompanyMember
Granted (Weighted-Average Grant Date Fair Value)	$ 37.86us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue / us-gaap_AwardTypeAxis = bx_BlackstonePartnershipUnitsMember / dei_LegalEntityAxis = us-gaap_ParentCompanyMember
Vested (Weighted-Average Grant Date Fair Value)	$ 27.17us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue / us-gaap_AwardTypeAxis = bx_BlackstonePartnershipUnitsMember / dei_LegalEntityAxis = us-gaap_ParentCompanyMember
Forfeited (Weighted-Average Grant Date Fair Value)	$ 25.17us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue / us-gaap_AwardTypeAxis = bx_BlackstonePartnershipUnitsMember / dei_LegalEntityAxis = us-gaap_ParentCompanyMember
Ending Balance	$ 30.64us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue / us-gaap_AwardTypeAxis = bx_BlackstonePartnershipUnitsMember / dei_LegalEntityAxis = us-gaap_ParentCompanyMember
Blackstone Group L P | Equity Settled Awards Weighted Average Grant Date Fair Value
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Beginning Balance	$ 16.95us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue / us-gaap_AwardTypeAxis = bx_EquitySettledAwardsWeightedAverageGrantDateFairValueMember / dei_LegalEntityAxis = bx_BlackstoneGroupLPMember
Granted (Weighted-Average Grant Date Fair Value)	$ 33.69us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue / us-gaap_AwardTypeAxis = bx_EquitySettledAwardsWeightedAverageGrantDateFairValueMember / dei_LegalEntityAxis = bx_BlackstoneGroupLPMember
Vested (Weighted-Average Grant Date Fair Value)	$ 14.01us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue / us-gaap_AwardTypeAxis = bx_EquitySettledAwardsWeightedAverageGrantDateFairValueMember / dei_LegalEntityAxis = bx_BlackstoneGroupLPMember
Forfeited (Weighted-Average Grant Date Fair Value)	$ 12.62us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue / us-gaap_AwardTypeAxis = bx_EquitySettledAwardsWeightedAverageGrantDateFairValueMember / dei_LegalEntityAxis = bx_BlackstoneGroupLPMember
Ending Balance	$ 21.09us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue / us-gaap_AwardTypeAxis = bx_EquitySettledAwardsWeightedAverageGrantDateFairValueMember / dei_LegalEntityAxis = bx_BlackstoneGroupLPMember
Blackstone Group L P | Cash Settled Awards Weighted Average Grant Date Fair Value
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Beginning Balance	$ 31.95us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue / us-gaap_AwardTypeAxis = bx_CashSettledAwardsWeightedAverageGrantDateFairValueMember / dei_LegalEntityAxis = bx_BlackstoneGroupLPMember
Granted (Weighted-Average Grant Date Fair Value)	$ 33.83us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue / us-gaap_AwardTypeAxis = bx_CashSettledAwardsWeightedAverageGrantDateFairValueMember / dei_LegalEntityAxis = bx_BlackstoneGroupLPMember
Vested (Weighted-Average Grant Date Fair Value)	$ 32.62us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue / us-gaap_AwardTypeAxis = bx_CashSettledAwardsWeightedAverageGrantDateFairValueMember / dei_LegalEntityAxis = bx_BlackstoneGroupLPMember
Ending Balance	$ 32.76us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue / us-gaap_AwardTypeAxis = bx_CashSettledAwardsWeightedAverageGrantDateFairValueMember / dei_LegalEntityAxis = bx_BlackstoneGroupLPMember
Blackstone Group L P | Equity Settled Awards Deferred Restricted Common Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Beginning Balance	17,569,372us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber / us-gaap_AwardTypeAxis = bx_EquitySettledAwardsDeferredRestrictedCommonUnitsMember / dei_LegalEntityAxis = bx_BlackstoneGroupLPMember
Granted (Units)	3,661,263us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod / us-gaap_AwardTypeAxis = bx_EquitySettledAwardsDeferredRestrictedCommonUnitsMember / dei_LegalEntityAxis = bx_BlackstoneGroupLPMember
Vested (Units)	(3,656,555)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod / us-gaap_AwardTypeAxis = bx_EquitySettledAwardsDeferredRestrictedCommonUnitsMember / dei_LegalEntityAxis = bx_BlackstoneGroupLPMember
Forfeited (Units)	(77,371)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod / us-gaap_AwardTypeAxis = bx_EquitySettledAwardsDeferredRestrictedCommonUnitsMember / dei_LegalEntityAxis = bx_BlackstoneGroupLPMember
Ending Balance	17,496,709us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber / us-gaap_AwardTypeAxis = bx_EquitySettledAwardsDeferredRestrictedCommonUnitsMember / dei_LegalEntityAxis = bx_BlackstoneGroupLPMember
Blackstone Group L P | Cash Settled Awards Phantom Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Beginning Balance	1,455us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber / us-gaap_AwardTypeAxis = bx_CashSettledAwardsPhantomUnitsMember / dei_LegalEntityAxis = bx_BlackstoneGroupLPMember
Granted (Units)	998us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod / us-gaap_AwardTypeAxis = bx_CashSettledAwardsPhantomUnitsMember / dei_LegalEntityAxis = bx_BlackstoneGroupLPMember
Vested (Units)	(815)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod / us-gaap_AwardTypeAxis = bx_CashSettledAwardsPhantomUnitsMember / dei_LegalEntityAxis = bx_BlackstoneGroupLPMember
Ending Balance	1,638us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber / us-gaap_AwardTypeAxis = bx_CashSettledAwardsPhantomUnitsMember / dei_LegalEntityAxis = bx_BlackstoneGroupLPMember

X

- Definition

The number of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)(1)(iv)(3)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Weighted average fair value as of the grant date of equity-based award plans other than stock (unit) option plans that were not exercised or put into effect as a result of the occurrence of a terminating event.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)(2)(iii)(3)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

+ Details

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Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

X

- Definition

The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)(2)(iii)(1)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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Balance Type:	na
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X

- Definition

The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)(2)(iii)(1)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

+ Details

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Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

X

- Definition

The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)(2)(i)-(ii)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

X

- Definition

The weighted average fair value of nonvested awards on equity-based plans excluding option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, revenue or profit achievement stock award plan) for which the employer is contingently obligated to issue equity instruments or transfer assets to an employee who has not yet satisfied service or performance criteria necessary to gain title to proceeds from the sale of the award or underlying shares or units.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)(2)(i)-(ii)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

+ Details

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Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

X

- Definition

The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)(2)(iii)(2)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

X

- Definition

The weighted average fair value as of grant date pertaining to an equity-based award plan other than a stock (or unit) option plan for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash in accordance with the terms of the arrangement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)(2)(iii)(2)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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Balance Type:	na
Period Type:	duration

X

- Details

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

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