Consolidated Statements of Financial Condition (Parenthetical) - USD ($)	Mar. 31, 2022	Dec. 31, 2021
Assets
Security Owned and Pledged as Collateral, Fair Value	$ 1,704,831,000	$ 1,764,853,000
Allowance for receivable from brokers	616,000	636,000
Allowance for receivable from customers	587,000	687,000
Allowance for fees receivable	828,000	886,000
Fixed assets, accumulated depreciation and amortization (in dollars)	52,254,000	50,017,000
Intangible assets, accumulated amortization (in dollars)	$ 37,470,000	$ 33,219,000
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, Liquidation Preference, Value	$ 120,750,000	$ 120,750,000
Common stock, shares authorized	125,000,000
Additional paid-in capital	$ 1,127,160,000	1,100,667,000
(Accumulated deficit) retained earnings	491,189,000	461,982,000
Accumulated other comprehensive income (loss)	0	(2,000)
Less: Class A common stock held in treasury, at cost, 29,220,380 and 28,047,929 shares as of March 31, 2022 and December 31, 2021, respectively	(583,500,000)	(547,100,000)
Loans and Leases Receivable, Allowance	834,000	0
Portfolio Funds
Assets
Investment Owned, at Fair Value	$ 131,766,000	$ 137,986,000
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	56,835,283	55,826,893
Common stock, shares outstanding	27,614,903	27,778,964
Treasury Stock, Shares	29,220,380	28,047,929
Less: Class A common stock held in treasury, at cost, 29,220,380 and 28,047,929 shares as of March 31, 2022 and December 31, 2021, respectively	$ (583,535,000)	$ (547,112,000)
Common Stock Class A | Restricted Stock
Stockholders' equity
Common stock, shares outstanding	901,374	901,374
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