Unvested Units, After Expected Forfeitures (Detail) - Jun. 30, 2015 - shares	Total
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Blackstone Holdings Partnership Units (Units)	29,450,530
Deferred Restricted Blackstone Common Units	13,345,470
Total Equity-Based Awards (Units)	42,796,000
Phantom Units (Units)	8,606
Blackstone Holdings Partnership Units (Weighted-Average Service Period in Years)	4 years 6 months
Deferred Restricted Blackstone Common Units	2 years 1 month 6 days
Total Equity-Based Awards (Weighted-Average Service Period in Years)	3 years 8 months 12 days
Phantom Units (Weighted-Average Service Period in Years)	3 years 6 months