Summary of Aggregate Notional Amount and Fair Value of Derivative Financial Instruments (Detail) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Derivatives, Fair Value [Line Items]
Derivative Assets, Notional	$ 725,662	$ 719,650
Derivative Liabilities, Notional	1,617,351	1,425,901
Derivative Assets, Fair Value	6,289	15,009
Derivative Liabilities, Fair Value	19,883	30,528
Net Investment Hedges | Foreign Currency Contracts
Derivatives, Fair Value [Line Items]
Derivative Assets, Notional	57,272	62,078
Derivative Assets, Fair Value	525	523
Freestanding Derivatives
Derivatives, Fair Value [Line Items]
Derivative Assets, Notional	668,390	657,572
Derivative Liabilities, Notional	1,617,351	1,425,901
Derivative Assets, Fair Value	5,764	14,486
Derivative Liabilities, Fair Value	19,883	30,528
Freestanding Derivatives | Foreign Currency Contracts | Blackstone - Other
Derivatives, Fair Value [Line Items]
Derivative Assets, Notional	201,936	192,163
Derivative Liabilities, Notional	119,061	148,873
Derivative Assets, Fair Value	2,154	2,798
Derivative Liabilities, Fair Value	757	681
Freestanding Derivatives | Foreign Currency Contracts | Investments Of Consolidated Blackstone Funds
Derivatives, Fair Value [Line Items]
Derivative Assets, Notional	63,531	199,364
Derivative Liabilities, Notional	106,827	250,244
Derivative Assets, Fair Value	1,134	8,915
Derivative Liabilities, Fair Value	7,580	21,875
Freestanding Derivatives | Interest Rate Contracts | Blackstone - Other
Derivatives, Fair Value [Line Items]
Derivative Assets, Notional	402,923	223,886
Derivative Liabilities, Notional	1,209,567	879,412
Derivative Assets, Fair Value	2,476	407
Derivative Liabilities, Fair Value	4,815	4,590
Freestanding Derivatives | Interest Rate Contracts | Investments Of Consolidated Blackstone Funds
Derivatives, Fair Value [Line Items]
Derivative Assets, Notional		22,659
Derivative Assets, Fair Value		2,281
Freestanding Derivatives | Credit Default Swaps | Blackstone - Other
Derivatives, Fair Value [Line Items]
Derivative Assets, Notional		19,500
Derivative Liabilities, Notional	98,500	56,000
Derivative Assets, Fair Value		85
Derivative Liabilities, Fair Value	4,445	868
Freestanding Derivatives | Credit Default Swaps | Investments Of Consolidated Blackstone Funds
Derivatives, Fair Value [Line Items]
Derivative Liabilities, Notional	83,396	91,372
Derivative Liabilities, Fair Value	$ 2,286	$ 2,514