Consolidated Statements of Financial Condition (Parenthetical) - USD ($)	Sep. 30, 2020		Dec. 31, 2019
Assets
Security Owned and Pledged as Collateral, Fair Value	$ 254,383,000		$ 941,595,000
Allowance for receivable from customers	653,000		650,000
Allowance for fees receivable	3,677,000		2,620,000
Allowance for receivable from brokers	730,000		721,000
Other investments	204,610,000		185,722,000
Fixed assets, accumulated depreciation and amortization (in dollars)	38,347,000		32,846,000
Intangible assets, accumulated amortization (in dollars)	$ 34,746,000		$ 26,395,000
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
Portfolio Funds
Assets
Other investments	$ 123,787,000	[1]	$ 114,504,000
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	48,662,355		47,215,938
Common stock, shares outstanding	26,569,335		28,610,357
Common stock, restricted shares	334,230		216,912
Treasury Stock, Shares	22,093,020		18,605,581
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

[1] In accordance with US GAAP, certain investments are measured at fair value using the net asset value per share (or its equivalent) as a practical expedient. Carried interest in portfolio funds have not been classified in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the condensed consolidated statement of financial condition.