Condensed Consolidated Statements of Changes in Equity - USD ($) $ in Thousands	Total	Common Stock	Preferred Stock Series D convertible preferred stock	Additional Paid-in Capital	Retained Earnings (Accumulated Deficit)	Accumulated Other Comprehensive Income (Loss)	Treasury Stock	Total Attributed To Stockholders	Non- controlling Interests
Beginning Balance (in shares) at Dec. 31, 2017		7,159,645	1,150,000				3,296,289
Beginning Balance at Dec. 31, 2017	$ 605,224	$ 105	$ 110,843	$ 1,216,173	$ (386,216)	$ (600)	$ (351,748)	$ 588,557	$ 16,667
Adjustment for adoption of ASU 2016-01 at Dec. 31, 2017					(178)	178
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	23,972				23,300			23,300	672
Net unrealized gain (loss) on securities available-for-sale	(249)					(249)		(249)
Foreign currency translation adjustments	10					10		10
Net subscriptions (redemptions) and other	(720)								(720)
Cash dividends declared, preferred	(2,084)			(2,084)				(2,084)
Cash dividends declared, common	(3,394)			(3,394)				(3,394)
Issuance of common shares related to employee stock transactions (in shares)		57,798
Issuance of common shares related to employee stock transactions	698			698				698
Taxes paid on stock-based compensation	(5,014)			(5,014)				(5,014)
Stock-based compensation	6,963			6,963				6,963
Ending Balance (in shares) at Mar. 31, 2018		7,217,443	1,150,000				3,296,289
Ending Balance at Mar. 31, 2018	625,406	$ 105	$ 110,843	1,213,342	(363,094)	(661)	$ (351,748)	608,787	16,619
Beginning Balance at Dec. 31, 2017	4,178
Increase (Decrease) in Redeemable Non-controlling Interests [Roll Forward]
Net income (loss) attributable to noncontrolling interests	(145)
Net subscriptions (redemptions) and other	129
Ending Balance at Mar. 31, 2018	4,162
Beginning Balance (in shares) at Dec. 31, 2018		6,997,382	1,150,000				3,555,242
Beginning 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 Stockholders' Equity [Roll Forward]
Net income (loss)	21,293				21,746			21,746	(453)
Net unrealized gain (loss) on securities available-for-sale	0
Foreign currency translation adjustments	6					6		6
Net subscriptions (redemptions) and other	(557)								(557)
Reclassification from other comprehensive (income) loss	726					726		726
Cash dividends declared, preferred	(2,084)			(2,084)				(2,084)
Cash dividends declared, common	$ (4,152)			(4,152)				(4,152)
Repurchases of common shares (in shares)	(147,962)	(147,962)					(147,962)
Repurchases of common shares	$ (14,999)						$ (14,999)	(14,999)
Issuance of common shares related to employee stock transactions (in shares)		129,505
Issuance of common shares related to employee stock transactions	449	$ 1		448				449
Taxes paid on stock-based compensation	(4,804)			(4,804)				(4,804)
Stock-based compensation	6,713			6,713				6,713
Ending Balance (in shares) at Mar. 31, 2019		6,978,925	1,150,000				3,703,204
Ending Balance at Mar. 31, 2019	646,458	$ 107	$ 110,843	$ 1,205,926	$ (289,119)	$ 1	$ (394,248)	$ 633,510	$ 12,948
Beginning Balance at Dec. 31, 2018	57,481
Increase (Decrease) in Redeemable Non-controlling Interests [Roll Forward]
Net income (loss) attributable to noncontrolling interests	1,175
Net subscriptions (redemptions) and other	347
Ending Balance at Mar. 31, 2019	$ 59,003