Concentrations of Credit Risk - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Concentration Risk [Line Items]
Securities Purchased Under Agreements to Resell	$ 19,134	$ 0
Securities Sold Under Agreements to Repurchase	75,563	120,787
Total receivable	83,347	89,098
Investment banking and investment management receivables collection periods (in days)	90 days
Collection period for restructuring transactions and private equity fee receivables (in days)	90 days
Bad debt expense	2,099	1,803	1,558
Marketable Securities	43,407	36,545
Percentage of marketable securities related to corporate and municipal bonds and other debt securities (as percent)	52.00%
Percentage of marketable securities related to seed capital investments and mutual funds (as a percent)	48.00%
Asset (Liability) Balance [Member]
Concentration Risk [Line Items]
Securities Purchased Under Agreements to Resell	19,134	0
Securities Sold Under Agreements to Repurchase	75,563	120,787
Market Value of Collateral Received or (Pledged) [Member]
Concentration Risk [Line Items]
Securities Purchased Under Agreements to Resell	19,112	0
Securities Sold Under Agreements to Repurchase	$ 75,708	$ 121,029