Consolidated Statements of Changes in Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Preferred Stock	Additional Paid-in Capital	Retained Earnings (Accumulated Deficit)	Accumulated Other Comprehensive Income (Loss)	Treasury Stock	Total Attributed To Shareholders	Non- controlling Interests	Series D preferred stock Preferred Stock	Cumulative Effect, Period of Adoption, Adjustment	Cumulative Effect, Period of Adoption, Adjustment Retained Earnings (Accumulated Deficit)	Cumulative Effect, Period of Adoption, Adjustment Accumulated Other Comprehensive Income (Loss)
Balance (in shares) at Dec. 31, 2017		7,159,645	1,150,000				3,296,289
Balance at Dec. 31, 2017	$ 605,224	$ 105	$ 110,843	$ 1,216,173	$ (386,216)	$ (600)	$ (351,748)	$ 588,557	$ 16,667		$ 0	$ (178)	$ 178
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	75,565				75,529			75,529	36
Net unrealized gain (loss) on securities available-for-sale	(292)					(292)		(292)
Foreign currency translation adjustment	(17)					(17)		(17)
Net subscriptions (redemptions) and other	(2,745)								(2,745)
Cash dividends declared. preferred	(8,337)			(8,337)				(8,337)
Cash dividends declared, common	(15,267)			(15,267)				(15,267)
Repurchase of common shares (in shares)		258,953					258,953
Repurchase of common shares	(27,501)						$ (27,501)	(27,501)
Issuance of common shares related to employee stock transactions (in shares)		96,690
Issuance of common shares related to employee stock transactions	1,544	$ 1		1,543				1,544
Taxes paid on stock-based compensation	(6,591)			(6,591)				(6,591)
Stock-based compensation	22,284			22,284				22,284
Balance (in shares) at Dec. 31, 2018		6,997,382	1,150,000				3,555,242
Balance at Dec. 31, 2018	643,867	$ 106	$ 110,843	1,209,805	(310,865)	(731)	$ (379,249)	629,909	13,958
Balance at Dec. 31, 2017	4,178
Increase (Decrease) in Redeemable Non-controlling Interests [Roll Forward]
Acquisition of business	55,500
Net income (loss)	515
Net subscriptions (redemptions) and other	(2,712)
Balance at Dec. 31, 2018	57,481
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	94,622				95,649			95,649	(1,027)
Net unrealized gain (loss) on securities available-for-sale	0
Foreign currency translation adjustment	14					14		14
Net subscriptions (redemptions) and other	(1,535)			838				838	(2,373)
Reclassification from other comprehensive (income) loss	726					726		726
Cash dividends declared. preferred	(8,337)			(8,337)				(8,337)
Cash dividends declared, common	(18,130)			(18,130)				(18,130)
Repurchase of common shares (in shares)		372,365					372,365
Repurchase of common shares	(40,000)						$ (40,000)	(40,000)
Issuance of common shares related to employee stock transactions (in shares)		184,263
Issuance of common shares related to employee stock transactions	1,553	$ 1		1,552				1,553
Taxes paid on stock-based compensation	(7,696)			(7,696)				(7,696)
Stock-based compensation	21,173			21,173				21,173
Balance (in shares) at Dec. 31, 2019		6,809,280	1,150,000				3,927,607
Balance at Dec. 31, 2019	686,257	$ 107	$ 110,843	1,199,205	(215,216)	9	$ (419,249)	675,699	10,558
Increase (Decrease) in Redeemable Non-controlling Interests [Roll Forward]
Net income (loss)	10,886
Net subscriptions (redemptions) and other	(4,522)
Balance at Dec. 31, 2019	63,845
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	81,255				79,957			79,957	1,298
Net unrealized gain (loss) on securities available-for-sale	0
Foreign currency translation adjustment	20					20		20
Net subscriptions (redemptions) and other	(2,224)			(167)				(167)	(2,057)
Conversion of preferred stock (in shares)		912,806								(1,150,000)
Conversion of preferred stock	0	$ 9		110,834				0		$ (110,843)
Cash dividends declared, common	(24,998)			(24,998)				(24,998)
Repurchase of common shares (in shares)		279,796					279,796
Repurchase of common shares	(32,500)						$ (32,500)	(32,500)
Issuance of common shares related to employee stock transactions (in shares)		141,176
Issuance of common shares related to employee stock transactions	186	$ 2		184				186
Taxes paid on stock-based compensation	(6,608)			(6,608)				(6,608)
Stock-based compensation	19,552			19,552				19,552
Balance (in shares) at Dec. 31, 2020		7,583,466	0				4,207,403
Balance at Dec. 31, 2020	720,940	$ 118	$ 0	$ 1,298,002	$ (135,259)	$ 29	$ (451,749)	$ 711,141	$ 9,799
Increase (Decrease) in Redeemable Non-controlling Interests [Roll Forward]
Net income (loss)	38,708
Net subscriptions (redemptions) and other	12,960
Balance at Dec. 31, 2020	$ 115,513