Net Investment Income (Detail) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017
Net Investment Income [Line Items]
Interest income		$ 102,000	$ 99,200
Dividend income		16,400	9,400
Investment expenses		(12,000)	(7,300)
Other investment results		4,000	5,600
Net investment income		124,126	115,538
Ares
Net Investment Income [Line Items]
Equity results	[1]	$ 13,700	5,200
Pillar Holdings and Funds | Pillar Capital Holdings Limited And Managed Funds
Net Investment Income [Line Items]
Equity results	[1]		$ 3,400

[1] See Note 3(g) of this Form 10-Q for discussion of the Pillar Investments, as defined therein, and limited partnership interests in certain subsidiaries of Ares