COMMITMENTS AND CONTINGENCIES (Detail) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2014	Dec. 31, 2015
Contingencies And Commitments [Line Items]
Accrued incentives (fund level)	$ 1,843,940,000		$ 1,843,940,000			$ 1,540,469,000
Compensation expense related to accrued incentives (fund level)	973,356,000		973,356,000			750,077,000
Capital commitments	532,800,000		532,800,000			469,400,000
Consolidated Funds
Contingencies And Commitments [Line Items]
Aggregate potential credit and investment commitments	2,600,000		$ 2,600,000			1,300,000,000
Highstar Capital
Contingencies And Commitments [Line Items]
Contingent consideration					$ 60,000,000
Performance period (in years)			7 years		7 years
Contingent consideration	23,700,000		$ 23,700,000			28,500,000
Contingent consideration income	1,300,000		4,800,000
Contingent consideration expense		$ 400,000		$ 1,900,000
Financial Guarantee | Consolidated Funds
Contingencies And Commitments [Line Items]
Other commitment	$ 0		$ 0			$ 142,400,000