Concentrations of Credit Risk (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Concentration Risk [Line Items]
Securities Purchased under Agreements to Resell	$ 2,191	$ 7,669
Securities Sold Under Agreements to Repurchase	44,000	106,499
Accounts Receivable (net of allowances of $1,313 and $1,362 at December 31, 2015 and 2014, respectively)	$ 175,497	136,280
Investment Banking And Investment Management Receivables Collection Periods	90 days
Collection Period For Restructuring Transactions And Private Equity Fee Receivables	90 days
Provision for Doubtful Accounts	$ 1,314	1,027	$ 2,099
Marketable Securities	$ 43,787	37,985
Percentage Of Marketable Securities Related To Corporate And Municipal Bonds And Other Debt Securities	86.00%
Percentage Of Marketable Securities Related To Seed Capital Investments And Mutual Funds	14.00%
Asset (Liability) Balance [Member]
Concentration Risk [Line Items]
Securities Purchased under Agreements to Resell	$ 2,191	7,669
Securities Sold Under Agreements to Repurchase	44,000	106,499
Market Value Of Collateral Received Or Pledged [Member]
Concentration Risk [Line Items]
Securities Purchased under Agreements to Resell	2,192	7,671
Securities Sold Under Agreements to Repurchase	$ 44,063	$ 106,632