Net Investment Income (Detail) (USD $)	3 Months Ended
	Mar. 31, 2014		Mar. 31, 2013
Net Investment Income [Line Items]
Interest income	$ 95,300,000		$ 83,500,000
Dividend income	13,600,000		15,100,000
Investment expenses	(7,000,000)		(5,000,000)
Other investment results	4,300,000		1,500,000
Net investment income	110,583,000		118,811,000
Homesite
Net Investment Income [Line Items]
Equity results			21,400,000	[1]
ORX
Net Investment Income [Line Items]
Equity results	400,000		700,000
Ares Management Limited Liability Company
Net Investment Income [Line Items]
Net investment income	100,000	[2]
Pillar Holdings and Funds | Pillar Capital Holdings Limited And Managed Funds
Net Investment Income [Line Items]
Equity results	$ 3,900,000	[2]	$ 1,600,000	[2]

[1] Homesite was sold on December 31, 2013.

[2] See Note 3(g) for discussion of the Pillar Investments and the investment in Ares.