Investments Summary of Other Equity Investments (Detail) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Schedule of Equity Method Investments [Line Items]
Equity Method Investment	$ 85,942	$ 86,287
G5 Evercore [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment	24,665	20,730
ABS [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment	37,890	41,567
Atalanta Sosnoff [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment	$ 23,387	$ 23,990