COMMITMENTS AND CONTINGENCIES (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Contingencies And Commitments [Line Items]
Accrued incentives (fund level)	$ 1,778,191,000		$ 1,778,191,000		$ 1,970,755,000
Compensation expense related to accrued incentives (fund level)	913,673,000		913,673,000		1,026,345,000
Capital commitments	460,400,000		460,400,000		565,400,000
Consolidated Funds
Contingencies And Commitments [Line Items]
Aggregate potential credit and investment commitments	11,300,000		11,300,000		2,100,000
Highstar Capital
Contingencies And Commitments [Line Items]
Contingent consideration			$ 60,000,000
Performance period (in years)			7 years
Contingent consideration	24,000,000		$ 24,000,000		$ 23,600,000
Contingent consideration income	$ 100,000	$ 2,900,000		$ 3,500,000
Contingent consideration expense			$ 500,000