Related Party Transactions - Additional Information (Detail) (USD $)	3 Months Ended	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Related Party Transaction [Line Items]
Founder's, other senior managing directors' and employees' investments	$ 715,500,000	$ 939,400,000	$ 715,500,000
Founder's, other senior managing directors' and employees' share of the Net Income Attributable to Redeemable Non-Controlling Interests		114,100,000	109,400,000	219,700,000
Management and Advisory Fees earned from affiliates		254,729,000	317,675,000	189,006,000
Interest from loans to affiliates		4,400,000	3,700,000	3,100,000
Partnership Unit to Blackstone Common Unit ratio		1
Cash saving in tax receivable agreements, percentage		85.00%
Reduction in due to pre IPO owners and others resulted from change in effective tax rate of corporate tax payers	197,800,000
Expected future payments under the tax receivable agreements		1,200,000,000
Expected future payments under the tax receivable agreements in years		15 years
After-tax net present value estimated payments		364,600,000
After-tax net present value discount rate assumption		15.00%
Payments made under tax receivable agreements and related tax benefits	$ 34,200,000