COMMITMENTS AND CONTINGENCIES (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Contingencies And Commitments [Line Items]
Accrued incentives (fund level)	$ 1,859,278,000		$ 1,859,278,000		$ 1,970,755,000
Compensation expense related to accrued incentives (fund level)	961,519,000		961,519,000		1,026,345,000
Capital commitments	433,100,000		433,100,000		565,400,000
Consolidated Funds
Contingencies And Commitments [Line Items]
Aggregate potential credit and investment commitments	17,700,000		17,700,000		2,100,000
Highstar Capital
Contingencies And Commitments [Line Items]
Contingent consideration			$ 60,000,000
Performance period (in years)			7 years
Contingent consideration	19,100,000		$ 19,100,000		$ 23,600,000
Contingent consideration income	$ 4,900,000	$ 1,300,000		$ 4,800,000
Contingent consideration expense			$ 4,500,000