CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Preferred Stock [Member]	Common Stock [Member]	Paid-in Capital [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Income [Member]
Beginning Balance at Dec. 31, 2013	$ 1,365,783	$ 165,756	$ 958	$ 1,329,792	$ (349,866)	$ 219,143
Net income	140,820				140,820
Change in unrealized gain on mortgage securities, net	27,283					27,283
Amounts related to cash flow hedges, net	(19,004)					(19,004)
Cash dividends:
Common	(130,423)			(6,365)	(124,058)
Preferred	(13,781)				(13,781)
Issuance of Series E preferred stock	18,180	18,180
Other additions to capital	1,913			1,913
Ending Balance at Dec. 31, 2014	1,390,771	183,936	958	1,325,340	(346,885)	227,422
Net income	108,325				108,325
Change in unrealized gain on mortgage securities, net	(98,202)					(98,202)
Amounts related to cash flow hedges, net	6,875					6,875
Cash dividends:
Common	(109,217)			(16,473)	(92,744)
Preferred	(15,160)				(15,160)
Issuance of Series E preferred stock	13,236	13,236
Other additions to capital	1,696			1,696
Ending Balance at Dec. 31, 2015	1,298,324	197,172	958	1,310,563	(346,464)	136,095
Net income	82,873				82,873
Change in unrealized gain on mortgage securities, net	(48,894)					(48,894)
Amounts related to cash flow hedges, net	18,585					18,585
Cash dividends:
Common	(91,093)			(23,592)	(67,501)
Preferred	(15,372)				(15,372)
Issuance of Series E preferred stock	1,887	1,887
Other additions to capital	1,377		2	1,375
Ending Balance at Dec. 31, 2016	$ 1,247,687	$ 199,059	$ 960	$ 1,288,346	$ (346,464)	$ 105,786