CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Cash flows from operating activities:
Net income (loss)	$ 3,729,698	$ 1,735,900	$ 344,461
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Amortization of Investment Securities premiums and discounts, net	973,968	1,470,801	794,205
Amortization of commercial real estate investment premiums and discounts, net	(238)
Amortization of intangibles	2,614	4,080	2,300
Amortization of deferred expenses	8,152	6,965	3,600
Amortization of contingent beneficial conversion feature and equity component of Convertible Senior Notes	17,101	18,017	7,550
Net (gains) losses on sales of Agency mortgage-backed securities and debentures	(424,086)	(432,139)	(206,846)
Net loss on extinguishment of 4% Convertible Senior Notes		162,340
Stock compensation expense	2,547	5,584	5,269
Impairment of goodwill	23,987
Loss on previously held equity interest in CreXus	18,896
Non-cash component of disposal of subsidiary		(1,177)
Realized loss on disposal of subsidiary	21,041
Unrealized (gains) losses on interest rate swaps	(2,002,200)	32,219	1,815,107
Net unrealized (gains) losses on interest-only Agency mortgage-backed securities	(244,730)	59,937	106,657
Net (gains) losses on trading assets	(1,509)	(20,525)	(21,398)
(Gain) loss on investment with affiliate, equity method			(98)
Unrealized (gains) losses on equity securities			100
Proceeds from repurchase agreements of RCap	1,453,216,892	733,739,097	877,734,065
Payments on repurchase agreements of RCap	(1,471,279,777)	(727,275,192)	(878,806,056)
Proceeds from reverse repurchase agreements of RCap	450,032,217	401,926,011	156,659,365
Payments on reverse repurchase agreements of RCap	(448,403,808)	(402,805,044)	(156,502,577)
Proceeds from reverse repurchase agreements of Shannon	866,560	680,525	166,354
Payments on reverse repurchase agreements of Shannon	(783,874)	(751,721)	(177,845)
Proceeds from securities borrowed	263,155,068	74,361,498	27,261,366
Payments on securities borrowed	(263,577,019)	(75,593,708)	(27,973,422)
Proceeds from securities loaned	484,836,546	185,657,591	54,126,121
Payments on securities loaned	(484,117,193)	(184,654,177)	(53,539,061)
Proceeds from U.S. Treasury securities	142,054,631	64,028,348	29,168,074
Payments on U.S. Treasury securities	(141,019,615)	(64,746,420)	(28,490,573)
Net payments on derivatives	(133,023)	(10,173)	(7,158)
Net change in:
Due to / from brokers	503
Other assets	3,897	(9,243)	(3,258)
Accrued interest and dividends receivable	141,207	(6,151)	(64,362)
Receivable for investment advisory income	10,891	1,820	(3,378)
Receivable from prime broker		3,272
Accrued interest payable	(25,975)	47,931	23,199
Accounts payable and other liabilities	3,909	3,241	(1,698)
Net cash provided by (used in) operating activities	(12,892,722)	7,639,507	2,420,063
Cash flows from investing activities:
Payments on purchases of Agency mortgage-backed securities and debentures	(39,071,377)	(86,161,777)	(69,065,069)
Proceeds from sales of Agency mortgage-backed securities and debentures	54,328,560	30,542,875	19,337,053
Principal payments on Agency mortgage-backed securities	21,748,131	35,133,544	23,565,709
Proceeds from Agency debentures called	2,147,205	1,801,283	1,124,000
Payments on purchase of corporate debt	(82,502)	(81,090)	(31,675)
Proceeds from corporate debt called	24,252	67,649
Principal payments on corporate debt	4,716	4,247	1,375
Acquisition of CreXus	(724,889)
Purchases of commercial real estate investments	(984,743)
Proceeds from sale of commercial real estate investments	20,192
Principal payments on commercial real estate investments	114,999
Earn out payment		(13,387)
Proceeds from derivatives	7,465	10,379	13,965
Purchase of investment in affiliate			(57,500)
Purchase of customer relationships			(3,555)
Purchase of equity securities			(3,990)
Proceeds from sales of equity securities		4,048
Payment on disposal of subsidiary	16,209	(800)
Net cash provided by (used in) investing activities	37,548,218	(18,693,029)	(25,119,687)
Cash flows from financing activities:
Proceeds from repurchase agreements	381,641,327	352,497,651	273,023,622
Principal payments on repurchase agreements	(404,583,138)	(340,273,744)	(253,387,283)
Proceeds from exercise of stock options	2,204	8,438	8,953
Net proceeds from issuance of 5% Convertible Senior Notes offering		727,500
Net payment on extinguishment of 4% Convertible Senior Notes		(617,476)
Net proceeds from direct purchases and dividend reinvestments	2,855	2,794	455,547
Net (payments) proceeds from follow-on offerings		(248)	5,351,846
Payments on participation sold	(200)
Net payment on share repurchase	(141,149)	(255,901)
Dividends paid	(1,640,748)	(2,149,872)	(2,041,489)
Net cash provided by (used in) financing activities	(24,718,849)	10,675,113	23,411,196
Net (decrease) increase in cash and cash equivalents	(63,353)	(378,409)	711,572
Cash and cash equivalents, beginning of period	615,789	994,198	282,626
Cash and cash equivalents, end of period	552,436	615,789	994,198
Supplemental disclosure of cash flow information:
Interest received	4,035,661	4,718,524	4,309,690
Dividends received	21,624	29,522	31,876
Investment advisory income received	54,534	84,483	75,827
Interest paid (excluding interest paid on interest rate swaps)	656,648	595,152	455,873
Net interest paid on interest rate swaps	885,234	892,656	876,099
Taxes paid	10,447	52,590	61,045
Noncash investing activities:
Receivable for investments sold	1,193,730	290,722
Payable for investments purchased	764,131	8,256,957	4,315,796
Net change in unrealized gains (losses) on available-for-sale securities, net of reclassification adjustment	(5,802,175)	44,254	1,844,346
Noncash financing activities:
Dividends declared, not yet paid	284,230	432,154	552,806
Conversion of Series B cumulative preferred stock		32,272	7,759
Contingent beneficial conversion feature on 4% Convertible Senior Notes	17,383	61,725	60,087
Equity component of 5% Convertible Senior Notes		11,717
7.625% Series C Cumulative Redeemable Preferred Stock
Cash flows from financing activities:
Net proceeds from Preferred offering		290,514
7.50% Series D Cumulative Redeemable Preferred Stock
Cash flows from financing activities:
Net proceeds from Preferred offering		$ 445,457