Consolidated Statements of Financial Condition (Parenthetical) - USD ($)	Dec. 31, 2017	Dec. 31, 2016
Allowance for Uncollectible Customer's Liability for Acceptances	$ 1,550,000	$ 0
Allowance for Doubtful Accounts Receivable, Current	1,736,000	0
Assets
Fixed assets, accumulated depreciation and amortization (in dollars)	28,355,000	23,867,000
Intangible assets, accumulated amortization (in dollars)	$ 33,081,000	$ 29,418,000
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
Common stock, shares authorized	125,000,000
Treasury Stock, Shares	12,133,276	9,810,802
Common Stock Class A
Stockholders' equity
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	62,500,000	62,500,000
Common stock, shares issued	41,765,296	36,542,091
Common stock, shares outstanding	29,632,020	26,731,289
Common stock, restricted shares	191,962	162,176
Treasury Stock, Shares	12,133,276	9,810,802
Common Stock Class B
Stockholders' equity
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	62,500,000	62,500,000
Common stock, shares issued	0	0
Common stock, shares outstanding	0	0