Borrowings - Additional Information (Detail) (USD $)			1 Months Ended
	Sep. 30, 2012	Dec. 31, 2011	Aug. 17, 2012 Blackstone Holdings Finance Co. L.L.C. 2023 Notes	Aug. 17, 2012 Blackstone Holdings Finance Co. L.L.C. 2042 Notes	Jul. 13, 2012 Revolving Credit Facility	Jul. 13, 2012 Revolving Credit Facility Amended Credit Facility
Debt Instrument [Line Items]
Credit facility maximum borrowing capacity					$ 1,020,000,000	$ 1,100,000,000
Maturity date of credit facility			Feb. 15, 2023	Aug. 15, 2042	Apr. 08, 2016	Jul. 13, 2017
Senior notes issued			400,000,000	250,000,000
Senior notes, interest rate			4.75%	6.25%
Senior Secured Notes due to non-consolidated affiliates	22,000,000	101,800,000
Subordinated Notes due to non-consolidated affiliates	317,600,000	323,600,000
Fair value of Senior Secured notes	10,600,000,000	7,400,000,000
Fair value of Subordinated notes	811,300,000	630,200,000
Fair value of Senior Secured notes due to affiliates	17,100,000	86,900,000
Fair value of Subordinated notes due to affiliates	226,700,000	205,400,000
Fair value of the CLO assets	$ 12,500,000,000	$ 8,700,000,000