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)	(476,409)								(476,409)				(476,409)
Net income (loss) attributable to noncontrolling interest	(90)																(90)
Unrealized gains (losses) on available-for-sale securities	631,472							631,472					631,472
Reclassification adjustment for net (gains) losses included in net income (loss)	(62,356)							(62,356)					(62,356)
Stock compensation expense	39						39						39
Net proceeds from direct purchase and dividend reinvestment	570					1	569						570
Equity contributions from (distributions to) noncontrolling interest	(115)																(115)
Common dividends declared, $0.30 per share in 2015 and $0.30 per share in 2016	(284,310)								(284,310)				(284,310)
Ending balance at Mar. 31, 2015	13,124,590		177,088	290,514	445,457	9,477	14,787,117	773,999	(3,364,147)				13,119,505				5,085
Preferred dividends declared			(3,648)	(5,719)	(8,625)					$ (3,648)	$ (5,719)	$ (8,625)		$ (3,648)	$ (5,719)	$ (8,625)
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)	(867,918)								(867,918)				(867,918)
Net income (loss) attributable to noncontrolling interest	(162)																(162)
Unrealized gains (losses) on available-for-sale securities	1,017,707							1,017,707					1,017,707
Reclassification adjustment for net (gains) losses included in net income (loss)	255							255					255
Stock compensation expense	69						69						69
Net proceeds from direct purchase and dividend reinvestment	524					1	523						524
Buyback of common stock	(102,711)					(111)	(102,600)						(102,711)
Equity contributions from (distributions to) noncontrolling interest	(231)																(231)
Common dividends declared, $0.30 per share in 2015 and $0.30 per share in 2016	(277,456)								(277,456)				(277,456)
Ending balance at Mar. 31, 2016	$ 11,658,007		177,088	290,514	445,457	$ 9,249	$ 14,573,760	$ 640,366	$ (4,487,982)				$ 11,648,452				$ 9,555
Preferred dividends declared			$ (3,648)	$ (5,719)	$ (8,625)					$ (3,648)	$ (5,719)	$ (8,625)		$ (3,648)	$ (5,719)	$ (8,625)

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