CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013		Jun. 30, 2012
Cash flows from operating activities:
Net income (loss)	$ 1,638,213	$ (91,159)	$ 2,508,491		$ 810,647
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Amortization of Investment Securities premiums and discounts, net	320,125	302,769	741,182		583,105
Amortization of commercial real estate investment premiums and discounts, net	492		492
Amortization of intangibles	323	633	646		1,224
Amortization of deferred expenses	2,038	1,838	4,076		2,738
Amortization of contingent beneficial conversion feature on convertible senior notes	3,876	6,232	7,200		14,060
Net (gains) losses on sales of Agency mortgage-backed securities and debentures	(147,998)	(94,837)	(330,841)		(175,136)
Stock compensation expense	945	1,011	1,762		2,860
Impairment of goodwill	23,987		23,987
Loss on previously held equity interest in CreXus	18,896		18,896
Unrealized (gains) losses on interest rate swaps	(1,109,022)	611,215	(1,434,756)		269,576
Net unrealized (gains) losses on interest-only Agency mortgage- backed securities	(111,521)	26,103	(191,648)		(4,774)
Net (gains) losses on trading assets	(70,424)	(1,105)	(55,595)		(3,976)
Proceeds from repurchase agreements of RCap	302,192,952	213,985,974	539,762,437		341,038,916
Payments on repurchase agreements of RCap	(312,346,171)	(214,067,318)	(550,946,586)		(336,809,273)
Proceeds from reverse repurchase agreements of RCap	84,402,455	130,785,187	189,362,118		185,681,953
Payments on reverse repurchase agreements of RCap	(79,653,078)	(130,254,085)	(187,758,014)		(186,831,887)
Proceeds from reverse repurchase agreements of Shannon	267,896	129,848	644,094		223,740
Payments on reverse repurchase agreements of Shannon	(255,042)	(145,820)	(608,337)		(238,411)
Proceeds from securities borrowed	76,474,674	12,741,368	130,273,831		19,424,651
Payments on securities borrowed	(76,211,213)	(13,084,242)	(130,537,913)		(19,961,246)
Proceeds from securities loaned	105,005,660	33,856,914	215,730,800		65,859,868
Payments on securities loaned	(105,051,475)	(33,620,656)	(215,254,870)		(65,551,662)
Proceeds from U.S. Treasury securities	39,150,789	15,289,185	60,834,425		31,097,679
Payments on U.S. Treasury securities	(38,397,508)	(17,754,440)	(60,554,625)		(31,840,754)
Net payments on derivatives	(42,958)	(18,309)	(44,448)		(17,460)
Net change in:
Due to / from brokers	659		659
Other assets	3,350	8,072	(18,128)		2,154
Accrued interest and dividends receivable	51,340	(1,562)	73,956		(12,130)
Receivable for investment advisory income	2,443	(1,135)	7,356		(1,193)
Accrued interest payable	(11,495)	45,711	(22,642)		35,854
Accounts payable and other liabilities	32,636	36,926	58,885		87,630
Net cash provided by (used in) operating activities	(3,820,856)	(1,305,682)	(7,703,110)		3,688,753
Cash flows from investing activities:
Payments on purchases of Agency mortgage-backed securities and debentures	(8,499,751)	(18,020,975)	(26,199,223)		(38,120,124)
Proceeds from sales of Agency mortgage-backed securities and debentures	13,459,639	5,145,156	28,944,048		9,915,497
Principal payments on Agency mortgage-backed securities	6,548,595	7,877,543	15,062,669		15,254,031
Proceeds from Agency debentures called	1,300,000	698,523	2,147,205		850,163
Payments on purchase of corporate debt	(19,899)	(9,900)	(23,382)		(9,900)
Proceeds from corporate debt called	24,252		24,252
Principal payments on corporate debt	610	125	1,521		1,460
Acquisition of CreXus	(724,424)		(724,424)
Purchases of commercial real estate investments	(230,000)		(230,000)
Principal payments on commercial real estate investments	20,840		20,840
Earn out payment					(13,387)
Proceeds from derivatives			7,465
Proceeds from sales of equity securities		4,048			4,048
Net cash provided by (used in) investing activities	11,879,862	(4,305,480)	19,030,971		(12,118,212)
Cash flows from financing activities:
Proceeds from repurchase agreements	123,341,832	84,206,888	224,973,415		167,136,997
Principal payments on repurchase agreements	(132,114,220)	(79,085,612)	(235,177,628)		(158,703,728)
Proceeds from exercise of stock options	1,939	3,549	2,204		5,391
Net proceeds from Series C Preferred offering		290,514			290,514
Net proceeds from issuance of 5% Convertible Senior Notes offering		727,500			727,500
Net proceeds from direct purchases and dividend reinvestments	670	845	1,431		845
Net (payments) proceeds from follow-on offerings					(231)
Payments on participation sold	(67)		(67)
Net payment on share repurchase			(141,149)
Dividends paid	(426,173)	(540,909)	(876,319)		(1,097,653)
Net cash provided by (used in) financing activities	(9,196,019)	5,602,775	(11,218,113)		8,359,635
Net (decrease) increase in cash and cash equivalents	(1,137,013)	(8,387)	109,748		(69,824)
Cash and cash equivalents, beginning of period	1,862,550	932,761	615,789	[1]	994,198
Cash and cash equivalents, end of period	725,537	924,374	725,537		924,374
Supplemental disclosure of cash flow information:
Interest received	1,078,672	1,186,292	2,266,874		2,311,295
Dividends received	6,431	7,521	13,528		15,804
Fees received	14,630	20,794	33,083		41,502
Interest paid (excluding interest paid on interest rate swaps)	168,898	115,764	353,324		249,863
Net interest paid on interest rate swaps	215,768	220,738	442,231		441,353
Taxes paid	4,057	7,766	6,439		29,167
Noncash investing activities:
Receivable for investments sold	1,499,140	1,320,996	1,499,140		1,320,996
Payable for investments purchased	2,833,214	7,387,410	2,833,214		7,387,410
Net change in unrealized gains (losses) on available-for-sale securities, net of reclassification adjustment	(3,292,494)	646,890	(4,342,488)		404,332
Noncash financing activities:
Dividends declared, not yet paid	396,888	535,898	396,888		535,898
Conversion of Series B cumulative preferred stock					32,272
Contingent beneficial conversion feature on 4% Convertible Senior Notes	4,550	23,020	8,513		46,341
Equity component of 5% Convertible Senior Notes		$ 11,717			$ 11,717

[1] Derived from the audited consolidated financial statements at December 31, 2012.