CONSOLIDATED STATEMENTS OF STOCKHOLDERS EQUITY (USD $)	Total	7.875% Series A Cumulative Redeemable Preferred Stock [Member]	6.00% Series B Cumulative Convertible Preferred Stock [Member]	7.625% Series C Cumulative Redeemable Preferred Stock [Member]	7.50% Series D Cumulative Redeemable Preferred Stock [Member]	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 [Member]	Accumulated Deficit 6.00% Series B Cumulative Convertible Preferred Stock [Member]	Accumulated Deficit 7.625% Series C Cumulative Redeemable Preferred Stock [Member]	Accumulated Deficit 7.50% Series D Cumulative Redeemable Preferred Stock [Member]	7.875% Series A Cumulative Redeemable Preferred Stock [Member]	7.625% Series C Cumulative Redeemable Preferred Stock [Member]	7.50% Series D Cumulative Redeemable Preferred Stock [Member]
Beginning balance at Dec. 31, 2009	$ 9,554,426,000					$ 5,531,000	$ 7,817,454,000	$ 1,891,317,000	$ (336,964,000)					$ 177,088,000
Preferred dividends declared		(14,593,000)	(3,440,000)							(14,593,000)	(3,440,000)
Net income (loss)	1,267,280,000								1,267,280,000
Unrealized gains (losses) on available-for-sale securities	(639,783,000)							(639,783,000)
Unrealized loss on interest rate swaps	94,899,000							94,899,000
Reclassification adjustment for net (gains) losses included in net income (loss)	(181,791,000)							(181,791,000)
Exercise of stock options	4,600,000					4,000	4,596,000
Stock option expense and long-term compensation expense	4,757,000						4,757,000
Conversion of Series B Cumulative Convertible preferred stock	23,081,000					24,000	23,057,000
Net proceeds from direct purchase and dividend reinvestment	278,783,000					157,000	278,626,000
Net proceeds from follow-on offering	1,047,355,000					600,000	1,046,755,000
Common dividends declared	(1,570,674,000)								(1,570,674,000)
Ending balance at Dec. 31, 2010	9,864,900,000					6,316,000	9,175,245,000	1,164,642,000	(658,391,000)					177,088,000
Preferred dividends declared		(14,593,000)	(2,261,000)							(14,593,000)	(2,261,000)
Net income (loss)	344,461,000								344,461,000
Unrealized gains (losses) on available-for-sale securities	2,036,894,000							2,036,894,000
Unrealized loss on interest rate swaps	14,298,000							14,298,000
Reclassification adjustment for net (gains) losses included in net income (loss)	(206,846,000)							(206,846,000)
Exercise of stock options	8,953,000					7,000	8,946,000
Stock option expense and long-term compensation expense	5,269,000					3,000	5,266,000
Conversion of Series B Cumulative Convertible preferred stock	7,759,000					9,000	7,750,000
Net proceeds from direct purchase and dividend reinvestment	455,547,000					262,000	455,285,000
Net proceeds from follow-on offering	5,351,846,000					3,105,000	5,348,741,000
Contingent beneficial conversion feature on 4% Convertible Senior Notes	67,637,000						67,637,000
Common dividends declared	(2,173,222,000)								(2,173,222,000)
Ending balance at Dec. 31, 2011	15,760,642,000					9,702,000	15,068,870,000	3,008,988,000	(2,504,006,000)					177,088,000
Preferred dividends declared		(14,593,000)	(289,000)	(14,297,000)	(10,351,000)					(14,593,000)	(289,000)	(14,297,000)	(10,351,000)
Net income (loss)	1,735,900,000								1,735,900,000
Unrealized gains (losses) on available-for-sale securities	482,765,000							482,765,000
Reclassification adjustment for net (gains) losses included in net income (loss)	(438,511,000)							(438,511,000)
Exercise of stock options	8,438,000					6,000	8,432,000
Stock option expense and long-term compensation expense	5,584,000						5,584,000
Conversion of Series B Cumulative Convertible preferred stock	32,272,000					40,000	32,232,000
Net proceeds from direct purchase and dividend reinvestment	2,794,000					2,000	2,792,000
Contingent beneficial conversion feature on 4% Convertible Senior Notes	61,725,000						61,725,000
Equity component on 5% Convertible Senior Notes	11,717,000						11,717,000
Offering expenses	(248,000)						(248,000)
Common dividends declared	(1,989,690,000)				(1,989,690,000)								(1,989,690,000)
Net proceeds from preferred stock offering															290,514,000	445,457,000
Extinguishment of convertible debt	(53,558,000)						(53,558,000)
Buyback of common stock	(397,050,000)					(278,000)	(396,772,000)
Other	5,223,000								5,223,000
Ending balance at Dec. 31, 2012	$ 15,924,444,000					$ 9,472,000	$ 14,740,774,000	$ 3,053,242,000	$ (2,792,103,000)					$ 177,088,000	$ 290,514,000	$ 445,457,000