Summary of Aggregate Notional Amount and Fair Value of Derivative Financial Instruments (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Derivatives, Fair Value [Line Items]
Derivative Assets, Notional	$ 1,319,676	$ 1,071,169
Derivative Liabilities, Notional	1,102,657	2,190,208
Derivative Assets, Fair Value	30,378	32,787
Derivative Liabilities, Fair Value	57,375	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	1,319,676	1,071,169
Derivative Liabilities, Notional	1,102,657	2,139,351
Derivative Assets, Fair Value	30,378	32,787
Derivative Liabilities, Fair Value	57,375	41,345
Freestanding Derivatives \| Blackstone \| Credit Default Swap
Derivatives, Fair Value [Line Items]
Derivative Assets, Notional	5,001	2,073
Derivative Liabilities, Notional	20,532	2,073
Derivative Assets, Fair Value	125	304
Derivative Liabilities, Fair Value	2,168	304
Freestanding Derivatives \| Consolidated Blackstone Funds \| Credit Default Swap
Derivatives, Fair Value [Line Items]
Derivative Assets, Notional	32,306	45,670
Derivative Liabilities, Notional	50,056	45,582
Derivative Assets, Fair Value	1,565	3,731
Derivative Liabilities, Fair Value	4,839	5,163
Freestanding Derivatives \| Consolidated Blackstone Funds \| Total Return Swaps
Derivatives, Fair Value [Line Items]
Derivative Assets, Notional	25,325	25,645
Derivative Assets, Fair Value	488	526
Freestanding Derivatives \| Foreign Currency Contracts \| Blackstone
Derivatives, Fair Value [Line Items]
Derivative Assets, Notional	198,028	279,050
Derivative Liabilities, Notional	98,298	296,252
Derivative Assets, Fair Value	782	2,097
Derivative Liabilities, Fair Value	570	2,975
Freestanding Derivatives \| Foreign Currency Contracts \| Consolidated Blackstone Funds
Derivatives, Fair Value [Line Items]
Derivative Assets, Notional	114,194	493,181
Derivative Liabilities, Notional	11,099	264,693
Derivative Assets, Fair Value	5,295	24,087
Derivative Liabilities, Fair Value	1,087	5,628
Freestanding Derivatives \| Interest Rate Contracts \| Blackstone
Derivatives, Fair Value [Line Items]
Derivative Assets, Notional	944,822	225,550
Derivative Liabilities, Notional	922,672	1,530,751
Derivative Assets, Fair Value	22,123	2,042
Derivative Liabilities, Fair Value	$ 48,711	$ 27,275

Nominal or face amount used to calculate payments on the derivative asset.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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