EQUITY - Schedule of Dividends and Distributions (Details) - USD ($) $ / shares in Units, $ in Thousands												1 Months Ended		3 Months Ended		9 Months Ended		12 Months Ended
	Aug. 31, 2020	May 29, 2020	Apr. 15, 2020	Feb. 28, 2020	Nov. 29, 2019	Sep. 26, 2019	Aug. 15, 2019	Jul. 31, 2019	May 02, 2019	Apr. 12, 2019	Feb. 28, 2019	Apr. 30, 2020	Apr. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Class of Stock [Line Items]
Dividends/Distributions	$ 212,100	$ 181,900	$ 43,000	$ 361,200	$ 201,600	$ 17,800	$ 4,100	$ 201,400	$ 185,200	$ 45,400	$ 226,600					$ 798,200		$ 882,100
Distribution to Non-Controlling Interest Holders in the Apollo Operating Group
Class of Stock [Line Items]
Distribution to Non-Controlling Interest Holders in the Apollo Operating Group	$ 100,000	$ 85,700	$ 43,000	$ 155,600	$ 90,100	$ 17,800	$ 4,100	$ 101,000	$ 93,000	$ 45,400	$ 113,300	$ 43,000	$ 37,400			$ 384,300		$ 464,700
Distribution made (in USD per share)												$ 0.21	$ 0.18
Distributions made related with federal corporate estimated tax payments (in USD per share)						$ 0.10	$ 0.02			$ 0.04
Class A Common Stock
Class of Stock [Line Items]
Dividends per share of Class A Common Stock (in USD per share)	$ 0.49	$ 0.42	$ 0	$ 0.89	$ 0.50	$ 0	$ 0	$ 0.50	$ 0.46	$ 0	$ 0.56					$ 1.80		$ 2.02
Dividends/Distributions	$ 112,100	$ 96,200	$ 0	$ 205,600	$ 111,500	$ 0	$ 0	$ 100,400	$ 92,200	$ 0	$ 113,300			$ 112,075	$ 100,355	$ 413,858	$ 305,901	$ 417,400
Distribution made (in USD per share)														$ 0.49	$ 0.50	$ 1.80	$ 1.52
Distribution Equivalents on Participating Securities
Class of Stock [Line Items]
Dividends/Distributions	$ 4,000	$ 3,600	$ 0	$ 7,200	$ 4,400	$ 0	$ 0	$ 4,400	$ 4,100	$ 0	$ 5,000					$ 14,800		$ 17,900