SEGMENT REPORTING - Expenses (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Segment Reporting Information [Line Items]
Total Segment Expenses	$ 740,090	$ 530,247	$ 1,851,741	$ 1,699,989
Deduct: Amortization of Intangibles	681	2,473	7,028	13,901
Segment Reconciling Items
Segment Reporting Information [Line Items]
Deduct: Equity-based and Other Compensation - KKR Holdings L.P.	25,327	23,807	87,269	127,864
Deduct: Segment Unrealized Performance Income Compensation	57,407	(19,826)	81,376	157,162
Deduct: Amortization of Intangibles	681	2,473	7,028	13,901
Deduct: Reimbursable Expenses	43,382	35,098	125,787	107,335
Deduct: Operating Expenses relating to Other Consolidated Entities	37,845	43,818	135,268	121,691
Deduct: One-time Non-recurring Costs	0	0	11,501	0
Add: Other	(18,368)	3,559	(27,676)	(19,397)
Reportable segments
Segment Reporting Information [Line Items]
Total Segment Expenses	$ 557,080	$ 448,436	1,375,836	$ 1,152,639
Deduct: One-time Non-recurring Costs			$ 11,500