Derivatives - Fair Values of Derivatives Reported on Condensed Consolidated Statements of Financial Condition (Detail) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Derivatives, Fair Value [Line Items]
Derivative Assets	$ 544	$ 1,048
Derivative Liabilities	189,457	195,689
Forward Foreign Currency Exchange Rate Contracts [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets	498	1,015
Derivative Liabilities	1,846	1,584
Total Return Swaps and Other [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets	46	33
Derivative Liabilities	7,132	531
LFI and Other Similar Deferred Compensation Arrangements [Member]
Derivatives, Fair Value [Line Items]
Derivative Liabilities	$ 180,479	$ 193,574