QUARTERLY FINANCIAL DATA (UNAUDITED) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								6 Months Ended	12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Jun. 30, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Selected Quarterly Financial Information [Abstract]
Revenues	$ (178,056)	$ 1,129,666	$ 971,620	$ 472,606	$ 1,024,073	$ 749,652	$ 1,015,800	$ 767,755		$ 2,395,836	$ 3,557,280	$ 2,040,018
Total Expenses	237,736	740,090	675,050	436,601	636,703	530,247	629,728	540,014		2,089,477	2,336,692	1,695,474
Total Investment Income (Loss)	(798,115)	833,288	1,330,786	584,530	274,142	177,953	500,990	610,695		1,950,489	1,563,780	630,681
Income (Loss) Before Taxes	(1,213,907)	1,222,864	1,627,356	620,535	661,512	397,358	887,062	838,436		2,256,848	2,784,368	975,225
Income Tax Expense (Benefit)	(143,294)	(129,405)	60,960	17,641	146,826	18,420	18,538	40,542		(194,098)	224,326	24,561
Net Income (Loss)	(1,070,613)	1,352,269	1,566,396	602,894	514,686	378,938	868,524	797,894		2,450,946	2,560,042	950,664
Less: Net Income (Loss) Attributable to Redeemable Noncontrolling Interests	(57,246)	12,236	(18,016)	25,674	9,776	20,876	22,387	20,933	$ 7,658	(37,352)	73,972	(8,476)
Less: Net Income (Loss) Attributable to Noncontrolling Interests	(628,726)	691,494	895,690	398,777	330,180	196,158	432,150	509,277		1,357,235	1,467,765	649,833
Net Income (Loss) Attributable to KKR & Co. Inc.	(384,641)	648,539	688,722	178,443	174,730	161,904	413,987	267,684		1,131,063	1,018,305	309,307
Preferred Dividends										33,364	33,364	22,235
Net Income (Loss) Attributable to KKR & Co. Inc. Class A Common Stockholders										1,097,699	984,941	287,072
Series A Preferred Units/Preferred Stock
Selected Quarterly Financial Information [Abstract]
Preferred Dividends	5,822	5,822	5,822	5,822	5,822	5,822	5,822	5,822		23,288	23,288	17,337
Series B Preferred Units/Preferred Stock
Selected Quarterly Financial Information [Abstract]
Preferred Dividends	2,519	2,519	2,519	2,519	2,519	2,519	2,519	2,519		10,076	10,076	4,898
Class A Common Stock
Selected Quarterly Financial Information [Abstract]
Net Income (Loss) Attributable to KKR & Co. Inc. Class A Common Stockholders	$ (392,982)	$ 640,198	$ 680,381	$ 170,102	$ 166,389	$ 153,563	$ 405,646	$ 259,343		$ 1,097,699	$ 984,941	$ 287,072
Net Income (Loss) Attributable to KKR & Co. Inc. Per Share of Class A Common Stock
Basic (in dollars per share)	$ (0.74)	$ 1.22	$ 1.33	$ 0.36	$ 0.35	$ 0.33	$ 0.87	$ 0.57		$ 2.14	$ 2.10	$ 0.64
Diluted (in dollars per share)	$ (0.74)	$ 1.17	$ 1.24	$ 0.32	$ 0.32	$ 0.30	$ 0.81	$ 0.52		$ 2.06	$ 1.95	$ 0.59
Weighted Average Shares of Class A Common Stock Outstanding
Basic (in shares)	532,266,521	525,240,214	510,586,631	487,704,838	481,165,742	471,758,886	466,170,025	453,695,846		514,102,571	468,282,642	448,905,126
Diluted (in shares)	532,266,521	545,672,953	548,745,498	535,918,274	520,156,583	506,873,177	501,177,423	496,684,340		533,707,039	506,288,971	483,431,048