CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Preferred Stock [Member]	Common Stock [Member]	Paid-in Capital [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Income [Member]	Total
Beginning Balance at Dec. 31, 2012	$ 188,992	$ 962	$ 1,367,199	$ (353,938)	$ 293,910	$ 1,497,125
Net income	0	0	0	126,487	0	126,487
Change in unrealized gain on mortgage securities, net	0	0	0	0	(101,001)	(101,001)
Amounts related to cash flow hedges, net	0	0	0	0	26,234	26,234
Cash dividends:
Common	0	0	(13,830)	(104,932)	0	(118,762)
Preferred	0	0	0	(17,536)	0	(17,536)
Redemption of convertible preferred stock	(187,109)	0	(19,924)	0	0	(207,033)
Conversion of preferred stock	(1,883)	2	1,881	0	0	0
Issuance of Series E preferred stock	165,756	0	0	0	0	165,756
Other additions to capital	0	0	1,752	53	0	1,805
Common share repurchases	0	(6)	(7,286)	0	0	(7,292)
Ending Balance at Dec. 31, 2013	165,756	958	1,329,792	(349,866)	219,143	1,365,783
Net income	0	0	0	140,820	0	140,820
Change in unrealized gain on mortgage securities, net	0	0	0	0	27,283	27,283
Amounts related to cash flow hedges, net	0	0	0	0	(19,004)	(19,004)
Cash dividends:
Common	0	0	(6,365)	(124,058)	0	(130,423)
Preferred	0	0	0	(13,781)	0	(13,781)
Redemption of convertible preferred stock						0
Issuance of Series E preferred stock	18,180	0	0	0	0	18,180
Other additions to capital	0	0	1,913	0	0	1,913
Ending Balance at Dec. 31, 2014	183,936	958	1,325,340	(346,885)	227,422	1,390,771
Net income	0	0	0	108,325	0	108,325
Change in unrealized gain on mortgage securities, net	0	0	0	0	(98,202)	(98,202)
Amounts related to cash flow hedges, net	0	0	0	0	6,875	6,875
Cash dividends:
Common	0	0	(16,473)	(92,744)	0	(109,217)
Preferred	0	0	0	(15,160)	0	(15,160)
Redemption of convertible preferred stock						0
Issuance of Series E preferred stock	13,236	0	0	0	0	13,236
Other additions to capital	0	0	1,696	0	0	1,696
Ending Balance at Dec. 31, 2015	$ 197,172	$ 958	$ 1,310,563	$ (346,464)	$ 136,095	$ 1,298,324