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 Interest	Series D preferred stock	Series D preferred stock Preferred Stock	Series D preferred stock Total Attributed To Shareholders
Balance (in shares) at Dec. 31, 2015		8,398,944	0				1,214,144
Balance at Dec. 31, 2015	$ 509,457	$ 96	$ 0	$ 1,140,875	$ (472,614)	$ (1,034)	$ (157,699)	$ 509,624	$ (167)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	48,502				48,502			48,502	0
Net unrealized gain (loss) on securities available-for-sale	241					241		241
Foreign currency translation adjustment	569					569		569
Net subscriptions (redemptions) (distributions) and other					(167)			(167)	167
Repurchase of common shares (in shares)		2,572,417					2,015,901
Repurchase of common shares	(233,757)	$ (6)		(47,204)			$ (186,547)	(233,757)
Issuance of common shares related to employee stock transactions (in shares)		62,486
Issuance of common shares related to employee stock transactions	1,055	$ 1		1,054				1,055
Cash dividends declared, common	(13,015)			(13,015)				(13,015)
Taxes paid on stock-based compensation	(1,530)			(1,530)				(1,530)
Stock-based compensation	11,449			11,449				11,449
Tax deficiencies from stock-based compensation	(1,298)			(1,298)				(1,298)
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
Balance at Dec. 31, 2015	73,864
Increase (Decrease) in Redeemable Non-controlling Interests [Roll Forward]
Net income (loss)	261
Net subscriptions (redemptions) and other	(36,859)
Balance at Dec. 31, 2016	37,266
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) (distributions) 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
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
Cash dividends declared, common	(13,545)			(13,545)				(13,545)
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
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) (distributions) and other	$ (2,745)								(2,745)
Issuance of stock, net of offering costs (in shares)	1,260,169
Cash dividends declared. preferred	$ (8,337)			(8,337)				(8,337)
Repurchase of common shares (in shares)	258,953	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
Cash dividends declared, common	(15,267)			(15,267)				(15,267)
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