SEGMENT REPORTING - Expenses (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Segment Reporting Information [Line Items]
Total Segment Expenses	$ 675,050	$ 629,728	$ 1,111,651	$ 1,169,742
Deduct: Amortization of Intangibles	1,317	5,062	6,347	11,428
Segment Reconciling Items
Segment Reporting Information [Line Items]
Deduct: Equity-based and Other Compensation - KKR Holdings L.P.	29,247	42,964	61,942	104,057
Deduct: Segment Unrealized Performance Income Compensation	67,092	119,774	23,969	176,988
Deduct: Amortization of Intangibles	1,317	5,062	6,347	11,428
Deduct: Reimbursable Expenses	56,312	43,438	82,405	72,237
Deduct: Operating Expenses relating to Other Consolidated Entities	53,114	44,093	97,423	77,873
Deduct: One-time Non-recurring Costs	11,501	0	11,501	0
Add: Other	(9,679)	(15,506)	(9,308)	(22,956)
Reportable segments
Segment Reporting Information [Line Items]
Total Segment Expenses	446,788	$ 358,891	818,756	$ 704,203
Deduct: One-time Non-recurring Costs	$ 11,500		$ 11,500