Consolidated Statements of Changes in Shareholders' Equity - USD ($) $ in Thousands	Total	7.625% Series A Cumulative Redeemable Preferred Stock	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Accumulated Other Comprehensive Income
Balance at Dec. 31, 2012	$ 3,072,864	$ 278,252	$ 99	$ 2,494,303	$ 37,356	$ 262,854
Repurchase of common stock	(43,881)		(2)	(43,879)
Share-based compensation expense	2,594			2,594
Dividends declared on preferred stock	(21,922)				(21,922)
Dividends declared on common stock	(240,512)				(240,512)
Net income (loss)	(134,136)				(134,136)
Other comprehensive income (loss)	(270,906)					(270,906)
Balance at Dec. 31, 2013	2,364,101	278,252	97	2,453,018	(359,214)	(8,052)
Repurchase of common stock	(1,912)			(1,912)
Share-based compensation expense	3,612			3,612
Dividends declared on preferred stock	(21,922)				(21,922)
Dividends declared on common stock	(193,261)				(193,261)
Net income (loss)	56,361				56,361
Other comprehensive income (loss)	213,817					213,817
Balance at Dec. 31, 2014	2,420,796	278,252	97	2,454,718	(518,036)	205,765
Repurchase of common stock	(20,753)		(1)	(20,752)
Share-based compensation expense	4,256			4,256
Dividends declared on preferred stock	(21,922)				(21,922)
Dividends declared on common stock	(183,534)				(183,534)
Net income (loss)	51,620				51,620
Other comprehensive income (loss)	(107,107)					(107,107)
Balance at Dec. 31, 2015	$ 2,143,357	$ 278,252	$ 96	$ 2,438,223	$ (671,872)	$ 98,658