Net Investment Income (Detail) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2016	Mar. 31, 2015
Net Investment Income [Line Items]
Interest income		$ 101,200	$ 94,700
Dividend income		12,100	14,500
Investment expenses		(6,900)	(7,300)
Other investment results		(5,000)	3,600
Net investment income		104,863	113,382
Ares
Net Investment Income [Line Items]
Equity results	[1]	400	2,300
ORX
Net Investment Income [Line Items]
Equity results			(1,000)
Pillar Holdings and Funds | Pillar Capital Holdings Limited And Managed Funds
Net Investment Income [Line Items]
Equity results	[1]	$ 3,100	$ 6,600

[1] See Note 3(g) for discussion of the Pillar Investments and the investment in Ares as defined therein.