Condensed Consolidated Statements of Financial Condition (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Accounts Receivable, allowances	$ 1,343	$ 1,362
Furniture, Equipment and Leasehold Improvements, accumulated depreciation and amortization	38,632	33,980
Intangible Assets, accumulated amortization	$ 41,495	$ 33,735
Treasury Stock, Shares	12,609,000	10,159,116
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	48,769,931	46,414,240
Common Stock, shares outstanding	36,160,931	36,255,124
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	26	27
Common Stock, shares outstanding	26	27