Consolidated Statements of Financial Condition (Parenthetical) - USD ($)	Jun. 30, 2016	Dec. 31, 2015
Assets
Fixed assets, accumulated depreciation and amortization (in dollars)	$ 26,876,000	$ 29,953,000
Intangible assets, accumulated amortization (in dollars)	$ 30,707,000	$ 28,301,000
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	120,750	120,750
Preferred stock, shares outstanding	120,750	120,750
Preferred Stock, Liquidation Preference, Value	$ 120,750,000	$ 120,750,000
Treasury Stock, Shares	38,749,780	34,515,734
Common Stock Class A
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	145,956,406	140,120,392
Common stock, shares outstanding	107,206,626	105,604,658
Common stock, restricted shares	648,704	497,570
Treasury Stock, Shares	38,749,780	34,515,734
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