Condensed Consolidated Statements of Financial Condition (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Accounts Receivable, allowances	$ 2,436	$ 3,886
Furniture, Equipment and Leasehold Improvements, accumulated depreciation and amortization	25,992	19,880
Intangible Assets, accumulated amortization	$ 27,538	$ 20,002
Treasury Stock at Cost, shares	7,702,900	5,463,515
Class A [Member]
Common Stock, par value	$ 0.01	$ 0.01
Common Stock, shares authorized	1,000,000,000	1,000,000,000
Common Stock, shares issued	40,772,434	35,040,501
Common Stock, shares outstanding	33,069,534	29,576,986
Class B [Member]
Common Stock, par value	$ 0.01	$ 0.01
Common Stock, shares authorized	1,000,000	1,000,000
Common Stock, shares issued	42	43
Common Stock, shares outstanding	42	43