Consolidated Statements of Financial Condition (Parenthetical) - USD ($)	Dec. 31, 2015	Dec. 31, 2014
Assets
Fixed assets, accumulated depreciation and amortization (in dollars)	$ 29,953,000	$ 25,968,000
Intangible assets, accumulated amortization (in dollars)	$ 28,301,000	$ 25,581,000
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	0
Preferred stock, shares outstanding	120,750	0
Preferred Stock, Liquidation Preference, Value	$ 120,750,000
Treasury Stock, Shares	34,515,734	23,507,656
Common stock, shares authorized	500,000,000
Common Stock Class A
Stockholders' equity
Treasury Stock, Shares	34,515,734	23,507,656
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	140,120,392	135,198,855
Common stock, shares outstanding	105,604,658	111,691,199
Common stock, restricted shares	497,570	424,479
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