CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock Par Value	Additional Paid-in Capital	Accumulated Other Comprehensive Income	Cumulative Earnings	Cumulative Distributions to Stockholders	Series A Preferred Stock Par Value	Series A Preferred Stock Par Value Preferred Stock	Series B Preferred Stock Par Value	Series B Preferred Stock Par Value Preferred Stock	Series C Preferred Stock Par Value	Series C Preferred Stock Par Value Preferred Stock	Series D Preferred Stock Par Value	Series D Preferred Stock Par Value Preferred Stock
Beginning Balance at Dec. 31, 2017	$ 3,634,977	$ 1,878	$ 3,826,691	$ 796,902	$ 2,967,852	$ (3,958,534)		$ 58		$ 130		$ 0		$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	514,435				514,435
Other comprehensive income (loss)	(168,966)			(168,966)
Repurchase of common stock	(14,834)	(8)	(14,826)
Stock based compensation	6,571		6,571
Common dividends declared	(281,778)					(281,778)
Preferred dividends declared	(28,760)					(28,760)	$ (9,000)		$ (20,000)
Issuance of preferred stock			251,432									104	$ 251,536
Ending Balance at Sep. 30, 2018	3,913,181	1,870	4,069,868	627,936	3,482,287	(4,269,072)		58		130		104		0
Beginning Balance at Jun. 30, 2018	3,650,140	1,870	3,816,631	671,651	3,324,966	(4,165,166)		58		130		0		0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	157,321				157,321
Other comprehensive income (loss)	(43,715)			(43,715)
Stock based compensation	1,805		1,805
Common dividends declared	(93,946)					(93,946)
Preferred dividends declared	(9,960)					(9,960)	(3,000)		(7,000)
Issuance of preferred stock	251,536		251,432									104
Ending Balance at Sep. 30, 2018	3,913,181	1,870	4,069,868	627,936	3,482,287	(4,269,072)		58		130		104		0
Beginning Balance at Dec. 31, 2018	3,703,829	1,871	4,072,093	626,832	3,379,489	(4,376,748)		58		130		104		0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	283,233				283,233
Other comprehensive income (loss)	142,238			142,238
Stock based compensation	9,341	1	9,340
Common dividends declared	(282,698)					(282,698)
Preferred dividends declared	(54,267)					(54,267)	(9,000)		(20,000)		$ (15,000)		(11,000)
Issuance of preferred stock			193,288										193,368	80
Ending Balance at Sep. 30, 2019	3,995,044	1,872	4,274,721	769,070	3,662,722	(4,713,713)		58		130		104		80
Beginning Balance at Jun. 30, 2019	3,968,950	1,872	4,272,001	739,090	3,556,396	(4,600,781)		58		130		104		80
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	106,326				106,326
Other comprehensive income (loss)	29,980			29,980
Stock based compensation	2,720		2,720
Common dividends declared	(94,494)					(94,494)
Preferred dividends declared	(18,438)					(18,438)	$ (3,000)		$ (7,000)		$ (5,000)		$ (4,000)
Ending Balance at Sep. 30, 2019	$ 3,995,044	$ 1,872	$ 4,274,721	$ 769,070	$ 3,662,722	$ (4,713,713)		$ 58		$ 130		$ 104		$ 80