Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Assets
Mortgage-backed securities, at fair value (including pledged assets of $24,163,526 and $22,591,973 at June 30, 2013 and December 31, 2012, respectively)	$ 25,256,043	$ 23,919,251
Cash and cash equivalents	88,987	168,424
Restricted cash	149,210	281,021
Unsettled purchased mortgage-backed securities, at fair value	133,597	138,338
Receivable for securities sold	7,251	1,587,535
Accrued interest receivable	73,957	77,113
Principal payments receivable	199,553	190,832
Debt security, held to maturity, at cost	15,000	15,000
Interest rate hedge asset	25,921
Other assets	26,856	26,604
Total assets	25,976,375	26,404,118
Liabilities and shareholders' equity
Repurchase agreements	23,077,252	22,866,429
Payable for unsettled securities	136,373	137,121
Accrued interest payable	4,773	7,592
Interest rate hedge liability	157,869	243,945
Dividend payable	73,809	73,804
Accounts payable and other liabilities	47,210	2,363
Total liabilities	23,497,286	23,331,254
Shareholders' equity:
7.625% Series A Cumulative Redeemable Preferred stock, $.001 par value, 25,000,000 shares authorized, 11,500,000 shares issued and outstanding at June 30, 2013 and December 31, 2012, respectively ($287,500 aggregate liquidation preference)	278,252	278,252
Common stock, $.001 par value, 200,000,000 shares authorized, 98,830,054 and 98,822,654 shares issued and outstanding at June 30, 2013 and December 31, 2012, respectively	99	99
Additional paid-in capital	2,495,559	2,494,303
Retained earnings	26,012	37,356
Accumulated other comprehensive (loss) income	(320,833)	262,854
Total shareholders' equity	2,479,089	3,072,864
Total liabilities and shareholders' equity	$ 25,976,375	$ 26,404,118