Variable Interest Entities ("VIEs") - Variable Interest Entities (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014		Dec. 31, 2013
Variable Interest Entity [Line Items]
Total VIE Assets	$ 1,946,979	[1]	$ 2,346,619	[1]
Carrying Value of Variable Interest Assets	3,819	[2]	767	[2]
Capital Commitments	2		5
Maximum Exposure to Loss in Non- consolidated VIEs	3,821		772
Hedge Funds [Member]
Variable Interest Entity [Line Items]
Total VIE Assets	1,870,079	[1]	2,282,144	[1]
Carrying Value of Variable Interest Assets	3,788	[2]	738	[2]
Maximum Exposure to Loss in Non- consolidated VIEs	3,788		738
Private Equity Funds [Member]
Variable Interest Entity [Line Items]
Total VIE Assets	76,900	[1]	64,475	[1]
Carrying Value of Variable Interest Assets	31	[2]	29	[2]
Capital Commitments	2		5
Maximum Exposure to Loss in Non- consolidated VIEs	$ 33		$ 34

[1] Represents the total assets of the VIEs and does not represent the Company’s interests in the VIEs.

[2] Represents the Company’s interests in the VIEs and is included in other assets on the condensed consolidated balance sheet.