EQUITY - Noncontrolling Interests Held by KKR Holdings (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Jun. 30, 2018	Sep. 30, 2018	Sep. 30, 2017
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Balance at the beginning of the period			$ 12,866,324	$ 12,866,324
Net income (loss) attributable to noncontrolling interests				1,985,961
Other comprehensive income (loss), net of tax				(39,127)
Exchange of KKR Holdings Units to Class A Common Stock and Other				(554,185)
Equity-based and other non-cash compensation				87,479
Capital contributions			2,410,722	3,537,037	$ 2,486,848
Capital distributions			(1,734,715)	(2,191,227)	(1,866,688)
Changes in consolidation				370,307
Balance at the end of the period	$ 16,062,569			16,062,569
Noncontrolling Interests in Consolidated Entities
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Balance at the beginning of the period			8,072,849	8,072,849
Net income (loss) attributable to noncontrolling interests				1,121,441
Other comprehensive income (loss), net of tax				(25,451)
Exchange of KKR Holdings Units to Class A Common Stock and Other				(52,585)
Equity-based and other non-cash compensation				0
Capital contributions				3,534,670
Capital distributions				(2,023,277)
Changes in consolidation				370,307
Balance at the end of the period	10,997,954			10,997,954
KKR Holdings
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Balance at the beginning of the period			$ 4,793,475	4,793,475
Net income (loss) attributable to noncontrolling interests	293,659	$ 115,434		864,520	$ 637,146
Other comprehensive income (loss), net of tax				(13,676)
Exchange of KKR Holdings Units to Class A Common Stock and Other				(501,600)
Equity-based and other non-cash compensation				87,479
Capital contributions				2,367
Capital distributions				(167,950)
Changes in consolidation				0
Balance at the end of the period	$ 5,064,615			$ 5,064,615