Commitments and Contingencies - Additional Information (Detail) $ in Millions	6 Months Ended
	Jun. 30, 2018 USD ($)
Schedule Of Commitments And Contingencies [Line Items]
General partner capital funding	$ 2,400.0
Total investments at risk in respect of guarantees extended	$ 15.9
Contingent obligations currently anticipated to expire end	2028
Provision for cash clawback	$ 696.5
Contingent Obligations (Clawback)	6,500.0
Blackstone Holdings
Schedule Of Commitments And Contingencies [Line Items]
Loans held By employees for investment guaranteed	185.7
Contingent Obligations (Clawback)	6,000.0
Consolidated Blackstone Funds
Schedule Of Commitments And Contingencies [Line Items]
Funds signed investment commitments	545.2
Consolidated Blackstone Funds | Portfolio Company Acquisition
Schedule Of Commitments And Contingencies [Line Items]
Signed investment commitments for portfolio company acquisitions in process of closing	$ 155.4