EQUITY (Details) - USD ($)		3 Months Ended
	Mar. 12, 2018	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
STOCKHOLDERS' EQUITY AND MEMBERS' CAPITAL
AOG Units (in units)		217,841,163		212,356,696
Direct Ownership Interest		100.00%		100.00%
Dividend rate, percentage		7.00%
Redemption price (dollars per unit)		$ 25.00
Preferred Equity
STOCKHOLDERS' EQUITY AND MEMBERS' CAPITAL
Issuance of common shares (in shares)		12,400,000		12,400,000
Ares Management, L.P.
STOCKHOLDERS' EQUITY AND MEMBERS' CAPITAL
AOG Units (in units)		97,514,500		82,280,033
Direct Ownership Interest		44.76%		38.75%
Daily Average Ownership		40.04%	38.35%
Ares Management, L.P. | Affiliate of Alleghany Corporation
STOCKHOLDERS' EQUITY AND MEMBERS' CAPITAL
Shares converted (in shares)		9,750,000
Ares Owners Holding L.P.
STOCKHOLDERS' EQUITY AND MEMBERS' CAPITAL
AOG Units (in units)		117,576,663		117,576,663
Direct Ownership Interest		53.98%		55.36%
Daily Average Ownership		54.98%	55.74%
Affiliate of Alleghany Corporation
STOCKHOLDERS' EQUITY AND MEMBERS' CAPITAL
AOG Units (in units)		2,750,000		12,500,000
Direct Ownership Interest		1.26%		5.89%
Daily Average Ownership		4.98%	5.91%
Ares Management L.P | Affiliate of Alleghany Corporation
STOCKHOLDERS' EQUITY AND MEMBERS' CAPITAL
Shares issued (in shares)		9,750,000
Secondary Offering
STOCKHOLDERS' EQUITY AND MEMBERS' CAPITAL
Number of units sold (in units)	15,000,000
Fees related to secondary offering	$ 500,000
Secondary Offering | ADIA
STOCKHOLDERS' EQUITY AND MEMBERS' CAPITAL
Number of units sold (in units)	10,000,000
Proceeds from sale of equity	$ 0
Secondary Offering | Ares Management L.P
STOCKHOLDERS' EQUITY AND MEMBERS' CAPITAL
Number of units sold (in units)	5,000,000
Proceeds from sale of equity	$ 105,900,000