CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total		7.875% Series A Cumulative Redeemable Preferred Stock	7.625% Series C Cumulative Redeemable Preferred Stock	7.50% Series D Cumulative Redeemable Preferred Stock	Common stock par value	Additional paid-in capital	Accumulated other comprehensive income (loss)	Accumulated deficit	Accumulated deficit 7.875% Series A Cumulative Redeemable Preferred Stock	Accumulated deficit 7.625% Series C Cumulative Redeemable Preferred Stock	Accumulated deficit 7.50% Series D Cumulative Redeemable Preferred Stock	Total stockholders' equity	Total stockholders' equity 7.875% Series A Cumulative Redeemable Preferred Stock	Total stockholders' equity 7.625% Series C Cumulative Redeemable Preferred Stock	Total stockholders' equity 7.50% Series D Cumulative Redeemable Preferred Stock	Noncontrolling interest
Beginning balance at Dec. 31, 2014	$ 13,333,781		$ 177,088	$ 290,514	$ 445,457	$ 9,476	$ 14,786,509	$ 204,883	$ (2,585,436)				$ 13,328,491				$ 5,290
Net income (loss)	423,811								423,811				423,811
Net income (loss) attributable to noncontrolling interest	(239)																(239)
Unrealized gains (losses) on available-for-sale securities	(493,571)							(493,571)					(493,571)
Reclassification adjustment for net (gains) losses included in net income (loss)	(66,277)							(66,277)					(66,277)
Stock compensation expense	1,024						1,024						1,024
Net proceeds from direct purchase and dividend reinvestment	1,146					2	1,144						1,146
Equity contributions from (distributions to) noncontrolling interest	(245)																(245)
Common dividends declared, $0.60 per share in 2015 and $0.60 per share in 2016	(568,641)								(568,641)				(568,641)
Ending balance at Jun. 30, 2015	12,594,805		177,088	290,514	445,457	9,478	14,788,677	(354,965)	(2,766,250)				12,589,999				4,806
Preferred dividends declared			(7,296)	(11,438)	(17,250)					$ (7,296)	$ (11,438)	$ (17,250)		$ (7,296)	$ (11,438)	$ (17,250)
Beginning balance at Dec. 31, 2015	11,905,922	[1]	177,088	290,514	445,457	9,359	14,675,768	(377,596)	(3,324,616)				11,895,974				9,948
Net income (loss)	(1,146,030)								(1,146,030)				(1,146,030)
Net income (loss) attributable to noncontrolling interest	(547)																(547)
Unrealized gains (losses) on available-for-sale securities	1,501,637							1,501,637					1,501,637
Reclassification adjustment for net (gains) losses included in net income (loss)	(6,995)							(6,995)					(6,995)
Stock compensation expense	1,084						1,084						1,084
Net proceeds from direct purchase and dividend reinvestment	1,176					1	1,175						1,176
Buyback of common stock	(102,712)					(111)	(102,601)						(102,712)
Equity contributions from (distributions to) noncontrolling interest	(743)																(743)
Common dividends declared, $0.60 per share in 2015 and $0.60 per share in 2016	(554,935)								(554,935)				(554,935)
Ending balance at Jun. 30, 2016	$ 11,561,873		177,088	290,514	445,457	$ 9,249	$ 14,575,426	$ 1,117,046	$ (5,061,565)				$ 11,553,215				$ 8,658
Preferred dividends declared			$ (7,296)	$ (11,438)	$ (17,250)					$ (7,296)	$ (11,438)	$ (17,250)		$ (7,296)	$ (11,438)	$ (17,250)

[1] Derived from the audited consolidated financial statements at December 31, 2015.