Summary of Aggregate Notional Amount and Fair Value of Derivative Financial Instruments (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Derivatives, Fair Value [Line Items]
Derivative Assets, Notional	$ 1,035,279	$ 1,071,169
Derivative Liabilities, Notional	2,020,181	2,190,208
Derivative Assets, Fair Value	8,284	32,787
Derivative Liabilities, Fair Value	69,793	41,798
Net Investment Hedges | Foreign Currency Contracts
Derivatives, Fair Value [Line Items]
Derivative Liabilities, Notional		50,857
Derivative Liabilities, Fair Value		453
Freestanding Derivatives
Derivatives, Fair Value [Line Items]
Derivative Assets, Notional	1,035,279	1,071,169
Derivative Liabilities, Notional	2,020,181	2,139,351
Derivative Assets, Fair Value	8,284	32,787
Derivative Liabilities, Fair Value	69,793	41,345
Freestanding Derivatives | Blackstone | Credit Default Swap
Derivatives, Fair Value [Line Items]
Derivative Assets, Notional	446	2,073
Derivative Liabilities, Notional	1,852	2,073
Derivative Assets, Fair Value	50	304
Derivative Liabilities, Fair Value	264	304
Freestanding Derivatives | Consolidated Blackstone Funds | Credit Default Swap
Derivatives, Fair Value [Line Items]
Derivative Assets, Notional	35,768	45,670
Derivative Liabilities, Notional	40,570	45,582
Derivative Assets, Fair Value	1,819	3,731
Derivative Liabilities, Fair Value	4,319	5,163
Freestanding Derivatives | Consolidated Blackstone Funds | Total Return Swaps
Derivatives, Fair Value [Line Items]
Derivative Assets, Notional	27,520	25,645
Derivative Assets, Fair Value	772	526
Freestanding Derivatives | Foreign Currency Contracts | Blackstone
Derivatives, Fair Value [Line Items]
Derivative Assets, Notional	465,677	279,050
Derivative Liabilities, Notional	345,181	296,252
Derivative Assets, Fair Value	2,151	2,097
Derivative Liabilities, Fair Value	1,093	2,975
Freestanding Derivatives | Foreign Currency Contracts | Consolidated Blackstone Funds
Derivatives, Fair Value [Line Items]
Derivative Assets, Notional	101,863	493,181
Derivative Liabilities, Notional	33,380	264,693
Derivative Assets, Fair Value	2,922	24,087
Derivative Liabilities, Fair Value	1,014	5,628
Freestanding Derivatives | Interest Rate Contracts | Blackstone
Derivatives, Fair Value [Line Items]
Derivative Assets, Notional	404,005	225,550
Derivative Liabilities, Notional	1,599,198	1,530,751
Derivative Assets, Fair Value	570	2,042
Derivative Liabilities, Fair Value	$ 63,103	$ 27,275