Investments Summary of Other Equity Investments (Detail) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Schedule of Equity Method Investments [Line Items]
Equity Method Investment	$ 71,581	$ 76,581
G5 Evercore [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment	31,525	32,756
ABS [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment	$ 40,056	$ 43,825