Consolidated Statements of Financial Condition (Parenthetical) - USD ($)	Mar. 31, 2016	Dec. 31, 2015
Assets
Fixed assets, accumulated depreciation and amortization (in dollars)	$ 29,457,000	$ 29,953,000
Intangible assets, accumulated amortization (in dollars)	$ 29,438,000	$ 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	36,638,529	34,515,734
Common Stock Class A
Stockholders' equity
Treasury Stock, Shares	36,638,529	34,515,734
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	142,716,734	140,120,392
Common stock, shares outstanding	106,078,205	105,604,658
Common stock, restricted shares	497,570	497,570
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