Investments Summary of Other Equity Investments (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Schedule of Equity Method Investments [Line Items]
Equity method investment	$ 76,593	$ 67,560
G5 Evercore [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment	33,915	20,001
ABS [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment	$ 42,678	$ 47,559