Condensed Consolidated Statements of Financial Condition (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Accounts Receivable, allowances	$ 1,817	$ 2,436
Furniture, Equipment and Leasehold Improvements, accumulated depreciation and amortization	31,592	25,992
Intangible Assets, accumulated amortization	$ 32,446	$ 27,538
Treasury Stock at Cost, shares	10,002,807	7,702,900
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	45,981,912	40,772,434
Common Stock, shares outstanding	35,979,105	33,069,534
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	27	42
Common Stock, shares outstanding	27	42