CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($)	Total	Preferred Stock [Member]	Common Stock [Member]	Paid-in Capital [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Income [Member]
Beginning Balance at Dec. 31, 2015	$ 1,298,324,000	$ 197,172,000	$ 958,000	$ 1,310,563,000	$ (346,464,000)	$ 136,095,000
Net income	82,873,000				82,873,000
Change in unrealized gain on mortgage securities, net	(48,894,000)					(48,894,000)
Amounts related to cash flow hedges, net	18,585,000					18,585,000
Cash dividends:
Common	(91,093,000)			(23,592,000)	(67,501,000)
Preferred	(15,372,000)				(15,372,000)
Issuance of Series E preferred stock	1,887,000	1,887,000
Other additions to capital	1,377,000		2,000	1,375,000
Ending Balance at Dec. 31, 2016	1,247,687,000	199,059,000	960,000	1,288,346,000	(346,464,000)	105,786,000
Cumulative effect adjustment- hedge ineffectiveness					(105,000)	105,000
Net income	79,589,000				79,589,000
Change in unrealized gain on mortgage securities, net	(60,391,000)					(60,391,000)
Amounts related to cash flow hedges, net	16,618,000					16,618,000
Cash dividends:
Common	(76,732,000)			(14,584,000)	(62,148,000)
Preferred	(17,442,000)				(17,442,000)
Issuance of Series E preferred stock	51,887,000	51,887,000
Common stock repurchases	(3,460,000)		(4,000)	(3,456,000)
Other additions to capital	1,120,000		1,000	1,119,000
Ending Balance at Dec. 31, 2017	1,238,876,000	250,946,000	957,000	1,271,425,000	(346,570,000)	62,118,000
Net income	50,072,000				50,072,000
Change in unrealized gain on mortgage securities, net	(72,490,000)					(72,490,000)
Amounts related to cash flow hedges, net	(10,674,000)					(10,674,000)
Cash dividends:
Common	(44,463,000)			(13,759,000)	(30,704,000)
Preferred	(19,368,000)				(19,368,000)
Common stock repurchases	(84,594,000)		(107,000)	(84,487,000)
Other additions to capital	1,704,000		3,000	1,701,000
Ending Balance at Dec. 31, 2018	$ 1,059,063,000	$ 250,946,000	$ 853,000	$ 1,174,880,000	$ (346,570,000)	$ (21,046,000)