Condensed Consolidated Statements of Financial Condition (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Assets
Fixed assets, accumulated depreciation and amortization (in dollars)	$ 22,876	$ 21,853
Intangible assets, accumulated amortization (in dollars)	$ 25,561	$ 26,610
Stockholders' equity
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Treasury Stock, Shares	19,961,735	15,873,549
Common Stock Class A
Stockholders' equity
Treasury Stock, Shares	19,961,735	15,873,549
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	250,000,000	250,000,000
Common stock, shares issued	134,928,538	130,900,182
Common stock, shares outstanding	114,966,803	115,026,633
Common stock, restricted shares	424,479	482,522
Common Stock Class B
Stockholders' equity
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	250,000,000	250,000,000
Common stock, shares issued	0	0
Common stock, shares outstanding	0	0