Derivatives - Fair Values of Derivatives Reported on Condensed Consolidated Statements of Financial Condition (Detail) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Derivatives, Fair Value [Line Items]
Derivative Assets	$ 2,595	$ 1,993
Derivative Liabilities	176,300	182,223
Forward Foreign Currency Exchange Rate Contracts [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets	2,595	1,993
Derivative Liabilities	2,694	2,792
Total Return Swaps and Other [Member]
Derivatives, Fair Value [Line Items]
Derivative Liabilities	5,648	9,043
LFI and Other Similar Deferred Compensation Arrangements [Member]
Derivatives, Fair Value [Line Items]
Derivative Liabilities	$ 167,958	$ 170,388