CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($)	Total	Preferred Stock [Member]	Common Stock [Member]	Paid-in Capital [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
Beginning 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 - adoption of ASU 2017-12 at Dec. 31, 2016					(105,000)	105,000
Net (loss) 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)
Stock issued during period, value, new issues	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 (loss) 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)
Net (loss) income	(35,338,000)				(35,338,000)
Change in unrealized gain on mortgage securities, net	72,513,000					72,513,000
Amounts related to cash flow hedges, net	(38,068,000)					(38,068,000)
Cash dividends:
Common	(42,763,000)				(42,763,000)
Preferred	(19,368,000)				(19,368,000)
Stock issued during period, value, new issues	75,102,000		90,000	75,012,000
Other additions to capital	2,592,000		3,000	2,589,000
Ending Balance at Dec. 31, 2019	$ 1,073,733,000	$ 250,946,000	$ 946,000	$ 1,252,481,000	$ (444,039,000)	$ 13,399,000