Consolidated Statements of Financial Condition (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Accounts Receivable, allowances	$ 3,886	$ 1,964
Furniture, Equipment and Leasehold Improvements, accumulated depreciation and amortization	19,880	13,490
Intangible assets, Accumulated Amortization	$ 20,002	$ 25,701
Treasury Stock at Cost, shares	5,463,515	3,072,958
Class A
Common Stock, par value	$ 0.01	$ 0.01
Common Stock, shares authorized	1,000,000,000	1,000,000,000
Common Stock, shares issued	35,040,501	31,014,265
Common Stock, shares outstanding	29,576,986	27,941,307
Class B
Common Stock, par value	$ 0.01	$ 0.01
Common Stock, shares authorized	1,000,000	1,000,000
Common Stock, shares issued	43	47
Common Stock, shares outstanding	43	47