Consolidated Balance Sheets (USD $)	Dec. 31, 2012		Dec. 31, 2011
Assets:
Residential mortgage investments($13.45 and $11.93 billion pledged under repurchase arrangements at December 31, 2012 and 2011, respectively)	$ 13,860,158,000	[1]	$ 12,264,906,000	[1]
Cash collateral receivable from interest rate swap counterparties	49,972,000		48,505,000
Interest rate swap agreements at fair value	169,000		617,000
Cash and cash equivalents	425,445,000		426,717,000
Receivables and other assets	130,402,000		100,760,000
Investments in unconsolidated affiliates	3,117,000		3,117,000
Assets, Total	14,469,263,000		12,844,622,000
Liabilities:
Repurchase arrangements and similar borrowings	12,784,238,000		11,352,444,000
Interest rate swap agreements at fair value	32,868,000		31,348,000
Unsecured borrowings	103,095,000		103,095,000
Common stock dividend payable	29,512,000		38,184,000
Accounts payable and accrued expenses	22,425,000		26,844,000
Liabilities, Total	12,972,138,000		11,551,915,000
Stockholders' equity:
Common stock - $0.01 par value; 250,000 shares authorized: 96,229 and 88,287 shares issued and outstanding at December 31, 2012 and December 31, 2011, respectively	962,000		883,000
Paid-in capital	1,367,199,000		1,257,653,000
Accumulated deficit	(353,938,000)		(354,883,000)
Accumulated other comprehensive income	293,910,000		204,540,000
Stockholders' Equity Attributable to Parent	1,497,125,000		1,292,707,000
Liabilities and Equity, Total	14,469,263,000		12,844,622,000
$1.60 Cumulative Preferred Stock, Series A [Member]
Stockholders' equity:
Cumulative Preferred Stock	2,604,000		2,605,000
Convertible Preferred Stock [Member] | $1.26 Cumulative Convertible Preferred Stock, Series B [Member]
Stockholders' equity:
Cumulative Preferred Stock	$ 186,388,000		$ 181,909,000

[1] Includes unrealized gains and losses for residential mortgage investments classified as available-for-sale (see NOTE 8).