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	Series D preferred stock Preferred Stock	Series D preferred stock Total Attributed To Shareholders
Balance (in shares) at Dec. 31, 2016		5,889,013	0				3,230,045
Balance at Dec. 31, 2016	$ 321,673	$ 91	$ 0	$ 1,090,331	$ (424,279)	$ (224)	$ (344,246)	$ 321,673	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	38,519				37,012			37,012	1,507
Net unrealized gain (loss) on securities available-for-sale	(388)					(388)		(388)
Foreign currency translation adjustment	12					12		12
Net subscriptions (redemptions) and other	15,160								15,160
Issuance of stock, net of offering costs (in shares)		1,046,500									1,150,000
Issuance of stock, net of offering costs	109,327	$ 11		109,316				109,327		$ 110,843	$ 110,843	$ 110,843
Cash dividends declared. preferred	(8,337)			(8,337)				(8,337)
Issuance of common stock for acquisition of business (in shares)		213,669
Issuance of common stock for acquisition of business	21,740	$ 2		21,738				21,740
Cash dividends declared, common	(13,545)			(13,545)				(13,545)
Repurchase of common shares (in shares)		(66,244)					(66,244)
Repurchase of common shares	(7,502)						$ (7,502)	(7,502)
Issuance of common shares related to employee stock transactions (in shares)		76,707
Issuance of common shares related to employee stock transactions	841	$ 1		840				841
Taxes paid on stock-based compensation	(3,499)			(3,499)				(3,499)
Stock-based compensation	19,329			19,329				19,329
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
Balance at Dec. 31, 2016	37,266
Increase (Decrease) in Redeemable Non-controlling Interests [Roll Forward]
Net income (loss)	1,420
Net subscriptions (redemptions) and other	(34,508)
Balance at Dec. 31, 2017	4,178
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
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)
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 Redeemable Non-controlling Interests [Roll Forward]
Reclassification from other comprehensive (income) loss	$ 726					$ 726		$ 726