CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Series A Preferred Stock Shares Outstanding	Series C Preferred Stock Shares Outstanding	Series A Preferred Stock	Series C Preferred Stock	Series B Preferred Stock	Common Stock Shares Outstanding	Common Stock	Additional Paid-In Capital	Accum. Other Comp. Income (Loss) Agency MBS	Accum. Other Comp. Income (Loss) Non-Agency MBS	Accum. Other Comp. (Loss) Derivatives	Accum. (Deficit)	Accum. (Deficit) Series A Preferred Stock	Accum. (Deficit) Series C Preferred Stock	Accum. (Deficit) Series B Preferred Stock
Beginning Balance at Dec. 31, 2013	$ 878,262			$ 46,537				$ 1,387	$ 1,185,369	$ (58,725)	$ 79	$ (33,362)	$ (263,023)
Beginning Balance (in shares) at Dec. 31, 2013		1,919					138,717
Issuance of common stock	1,372							3	1,369
Issuance of common stock (in shares)							295
Redemption of common stock	(150,174)							(290)	(149,884)
Redemption of common stock (in shares)							(29,040)
Other comprehensive income, fair value adjustments and reclassifications	77,027									90,321	(74)	(13,220)
Net income	28,619												28,619
Shares repurchased pending retirement	(3,936)								(3,936)
Shares repurchased pending retirement (in shares)							(738)
Amortization of restricted stock	97								97
Dividend declared				(4,139)		$ (1,577)								$ (4,139)		$ (1,577)
Dividend declared per common share	(68,034)												(68,034)
Ending Balance at Dec. 31, 2014	757,517			46,537				1,100	1,033,015	31,596	5	(46,582)	(308,154)
Ending Balance (in shares) at Dec. 31, 2014		1,919					109,234
Issuance of Preferred Stock	10,039				$ 10,039
Issuance of Preferred Stock (in shares)			434
Issuance of common stock	1,112							2	1,110
Issuance of common stock (in shares)							224
Redemption of common stock	(52,702)							(111)	(52,591)
Redemption of common stock (in shares)							(10,381)
Other comprehensive income, fair value adjustments and reclassifications	15,930									(8,453)	2,358	22,025
Net income	14,704												14,704
Shares repurchased pending retirement	(597)								(597)
Shares repurchased pending retirement (in shares)							(133)
Amortization of restricted stock	97								97
Dividend declared				(4,140)	(723)	(1,577)								(4,140)	$ (723)	(1,577)
Dividend declared per common share	(61,433)												(61,433)
Ending Balance at Dec. 31, 2015	678,227			46,537	10,039			991	981,034	23,143	2,363	(24,557)	(361,323)
Ending Balance (in shares) at Dec. 31, 2015		1,919	434				98,944
Issuance of Preferred Stock	1,282				1,282
Issuance of Preferred Stock (in shares)			52
Issuance of common stock	1,116							2	1,114
Issuance of common stock (in shares)							235
Redemption of common stock	(15,807)							(36)	(15,771)
Redemption of common stock (in shares)							(3,461)
Other comprehensive income, fair value adjustments and reclassifications	7,699									1,726	(827)	6,800
Net income	22,493												22,493
Amortization of restricted stock	337								337
Dividend declared				(4,139)	(867)	$ (1,577)								$ (4,139)	$ (867)	$ (1,577)
Dividend declared per common share	(57,666)												(57,666)
Ending Balance at Dec. 31, 2016	$ 631,098			$ 46,537	$ 11,321			$ 957	$ 966,714	$ 24,869	$ 1,536	$ (17,757)	$ (403,079)
Ending Balance (in shares) at Dec. 31, 2016		1,919	486				95,718