AGNC Investment (AGNC) 10-K 27 Feb 14 2013 Q4 Annual report Financial data

Document_and_Entity_Informatio

Document and Entity Information (USD $)	12 Months Ended
In Billions, except Share data, unless otherwise specified	Dec. 31, 2013	Jan. 31, 2014	Jun. 30, 2013
Document and Entity Information [Abstract]	'	'	'
Document Type	'10-K	'	'
Amendment Flag	'false	'	'
Document Period End Date	31-Dec-13	'	'
Document Fiscal Year Focus	'2013	'	'
Document Fiscal Period Focus	'Q4	'	'
Entity Registrant Name	'American Capital Agency Corp	'	'
Entity Central Index Key	'0001423689	'	'
Entity Filer Category	'Large Accelerated Filer	'	'
Current Fiscal Year End Date	'--12-31	'	'
Entity Common Stock, Shares Outstanding	'	356,151,654	'
Trading Symbol	'AGNC	'	'
Entity Well-known Seasoned Issuer	'Yes	'	'
Entity Voluntary Filers	'No	'	'
Entity Current Reporting Status	'Yes	'	'
Entity Public Float	'	'	$8.60

Consolidated_Balance_Sheets

Consolidated Balance Sheets (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Millions, unless otherwise specified
Assets:	'	'
Agency securities, at fair value	$64,482	$83,710
Agency securities transferred to consolidated variable interest entities, at fair value	1,459	1,535
U.S. Treasury securities, at fair value	3,822	0
REIT equity securities, at fair value	237	0
Cash and cash equivalents	2,143	2,430
Restricted cash	101	399
Derivative assets, at fair value	1,194	301
Receivable for agency securities sold	652	0
Receivable under reverse repurchase agreements	1,881	11,818
Other assets	284	260
Total assets	76,255	100,453
Liabilities:	'	'
Repurchase agreements	63,533	74,478
Other debt	910	937
Payable for agency securities purchased	118	556
Derivative liabilities, at fair value	422	1,264
Dividend payable	235	427
Obligation to return securities borrowed under reverse repurchase agreements, at fair value	1,848	11,763
Accounts payable and other accrued liabilities	492	132
Total liabilities	67,558	89,557
Stockholders' equity:	'	'
Preferred Stock, Value, Issued	167	167
Common stock	4	3
Additional paid-in capital	10,406	9,460
Retained earnings (deficit)	-497	-289
Accumulated other comprehensive income	-1,383	1,555
Total stockholders' equity	8,697	10,896
Total liabilities and stockholders' equity	$76,255	$100,453

Consolidated_Balance_Sheets_Pa

Consolidated Balance Sheets (Parentheticals) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Millions, except Per Share data, unless otherwise specified
Available-for-sale Securities Pledged as Collateral	$62,205	$79,966
Trading Securities Pledged as Collateral	3,778	'
Assets Pledged included in Receivable for Securities Sold	622	0
Preferred Stock, Par or Stated Value Per Share	$0.01	$0.01
Preferred Stock, Shares Authorized	10	10
Preferred Stock, Shares Issued	6.9	6.9
Preferred Stock, Shares Outstanding	6.9	6.9
Pref'd Stock Liquidation Preference	$173	$173
Common Stock, Par or Stated Value Per Share	$0.01	$0.01
Common Stock, Shares Authorized	600	600
Common Stock, Shares, Issued	356.2	338.9
Common Stock, Shares, Outstanding	356.2	338.9

Consolidated_Statements_Of_Com

Consolidated Statements Of Comprehensive Income (USD $)	3 Months Ended								12 Months Ended
In Millions, except Per Share data, unless otherwise specified	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Interest income:	'	'	'	'	'	'	'	'	'	'	'
Interest income	$542	$558	$545	$547	$570	$520	$504	$514	$2,193	$2,109	$1,109
Interest expense	120	145	131	140	147	139	120	106	536	512	285
Net interest income	422	413	414	407	423	381	384	408	1,657	1,597	824
Other income, net:	'	'	'	'	'	'	'	'	'	'	'
Gain on sale of agency securities, net	-667	-733	17	-26	353	210	417	216	-1,408	1,196	473
(Loss) gain on derivative instruments and other securities, net	184	-339	1,444	-98	89	-460	-1,029	47	1,191	-1,353	-447
Total other income, net	-483	-1,072	1,461	-124	442	-250	-612	263	-217	-157	26
Expenses:	'	'	'	'	'	'	'	'	'	'	'
Management fees	31	35	37	33	31	32	28	22	136	113	55
General and administrative expenses	6	7	9	9	9	8	8	6	32	31	19
Total expenses	37	42	46	42	40	40	36	28	168	144	74
Income before income tax	-98	-701	1,829	241	825	91	-264	643	1,272	1,296	776
Income tax benefit, net	3	0	0	10	15	5	-3	2	13	19	6
Dividend on preferred stock	3	3	3	3	3	3	3	0	14	10	0
Net income	-101	-701	1,829	231	810	86	-261	641	1,259	1,277	770
Net (loss) income (attributable) available to common shareholders	-104	-704	1,826	228	807	83	-264	641	1,245	1,267	770
Other comprehensive income (loss):	'	'	'	'	'	'	'	'	'	'	'
Unrealized gain (loss) on available-for-sale securities, net	-311	833	-2,813	-837	-734	1,190	689	-106	-3,127	1,039	1,029
Unrealized (loss) gain on derivative instruments, net	46	47	48	49	50	51	52	52	189	205	-650
Other comprehensive income (loss)	-265	880	-2,765	-788	-684	1,241	741	-54	-2,938	1,244	379
Comprehensive income	-366	179	-936	-557	126	1,327	480	587	-1,679	2,521	1,149
Dividend on preferred stock	3	3	3	3	3	3	3	0	14	10	0
Comprehensive income available to common shareholders	($369)	$176	($939)	($560)	$123	$1,324	$477	$587	($1,693)	$2,511	$1,149
Weighted average number of common shares outstanding-basic and diluted	373	390.6	396.4	356.2	340.3	332.8	301	240.6	379.1	303.9	153.3
Net income per common share - basic and diluted	($0.28)	($1.80)	$4.61	$0.64	$2.37	$0.25	($0.88)	$2.66	$3.28	$4.17	$5.02
Comprehensive income per share - basic and diluted	($0.99)	$0.45	($2.37)	($1.57)	$0.36	$3.98	$1.58	$2.44	($4.47)	$8.26	$7.50
Dividends declared per common share	$0.65	$0.80	$1.05	$1.25	$1.25	$1.25	$1.25	$1.25	'	'	'

Consolidated_Statement_of_Stoc

Consolidated Statement of Stockholders' Equity (USD $)	Total	Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings (Accumulated Deficit) [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
In Millions, unless otherwise specified
Balance, value at Dec. 31, 2010	$1,573	$0	$1	$1,562	$78	($68)
Balance, Common Stock, shares at Dec. 31, 2010	'	'	64.9	'	'	'
Balance, Preferred Stock, shares at Dec. 31, 2010	'	0	'	'	'	'
Net income	770	'	'	'	770	'
Other comprehensive income (loss):	'	'	'	'	'	'
Unrealized gain (loss) on available-for-sale securities, net	1,029	'	'	'	'	1,029
Unrealized (loss) gain on derivative instruments, net	-650	'	'	'	'	-650
Proceeds from Issuance of Preferred Stock and Preference Stock	0	'	'	'	'	'
Issuance of common stock, value	4,376	'	1	4,375	'	'
Issuance of common stock, shares	'	'	159.3	'	'	'
Common dividends declared	886	'	'	'	'	'
Balance, value at Dec. 31, 2011	6,212	0	2	5,937	-38	311
Balance, Common Stock, shares at Dec. 31, 2011	'	'	224.2	'	'	'
Balance, Preferred Stock, shares at Dec. 31, 2011	'	0	'	'	'	'
Net income	1,277	'	'	'	1,277	'
Other comprehensive income (loss):	'	'	'	'	'	'
Unrealized gain (loss) on available-for-sale securities, net	1,039	'	'	'	'	1,039
Unrealized (loss) gain on derivative instruments, net	205	'	'	'	'	205
Preferred Units, Issued	6.9	'	'	'	'	'
Proceeds from Issuance of Preferred Stock and Preference Stock	167	'	'	'	'	'
Issuance of common stock, value	3,601	'	1	3,600	'	'
Stock Repurchased During Period, Shares	-2.7	'	'	'	'	'
Dividends, Preferred Stock, Cash	-10	'	'	'	'	'
Stock Repurchased During Period, Value	-77	'	'	'	'	'
Issuance of common stock, shares	'	'	117.4	'	'	'
Common dividends declared	1,518	'	'	'	'	'
Balance, value at Dec. 31, 2012	10,896	167	3	9,460	-289	1,555
Balance, Common Stock, shares at Dec. 31, 2012	338.9	'	338.9	'	'	'
Balance, Preferred Stock, shares at Dec. 31, 2012	6.9	6.9	'	'	'	'
Net income	1,259	'	'	'	1,259	'
Other comprehensive income (loss):	'	'	'	'	'	'
Unrealized gain (loss) on available-for-sale securities, net	-3,127	'	'	'	'	-3,127
Unrealized (loss) gain on derivative instruments, net	189	'	'	'	'	189
Proceeds from Issuance of Preferred Stock and Preference Stock	0	'	'	'	'	'
Issuance of common stock, value	1,803	'	1	1,802	'	'
Stock Repurchased During Period, Shares	-40.2	'	-40.3	'	'	'
Dividends, Preferred Stock, Cash	-14	'	'	'	'	'
Stock Repurchased During Period, Value	-856	'	'	'	'	'
Issuance of common stock, shares	'	'	57.5	'	'	'
Common dividends declared	1,453	'	'	'	'	'
Balance, value at Dec. 31, 2013	$8,697	$167	$4	$10,406	($497)	($1,383)
Balance, Common Stock, shares at Dec. 31, 2013	356.2	'	356.2	'	'	'
Balance, Preferred Stock, shares at Dec. 31, 2013	6.9	6.9	'	'	'	'

Consolidated_Statements_Of_Cas

Consolidated Statements Of Cash Flows (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Operating activities:	'	'	'
Net income (loss)	$1,259	$1,277	$770
Adjustments to reconcile net income to net cash provided by operating activities:	'	'	'
Amortization of agency securities premiums and discounts, net	517	667	361
Amortization of accumulated other comprehensive loss on interest rate swaps de-designated as qualifying hedges	189	205	54
Gain on sale of agency securities, net	1,408	-1,196	-473
Loss (gain) on derivative instruments and other securities, net	-1,191	1,353	447
Increase in other assets	-24	-76	-121
Increase in accounts payable and other accrued liabilities	325	86	32
Accretion of discounts on debt of consolidated variable interest entities	18	5	0
Net cash provided by operating activities	2,501	2,321	1,070
Investing activities:	'	'	'
Purchases of agency securities	-76,892	-104,703	-81,484
Proceeds from sale of agency securities	79,456	65,249	37,868
Principal collections on agency securities	10,589	9,576	4,633
Purchases of U.S. Treasury securities	-68,261	-28,196	-21,944
Proceeds from sale of U.S. Treasury securities	54,952	39,012	22,397
Proceeds from reverse repurchase agreements	9,937	-11,055	-516
Net (payments) receipts on other derivative instruments not designated as qualifying hedges	-1,007	-1,001	-266
Purchases of REIT equity securities	-197	0	0
Decrease in restricted cash	298	-63	-260
Net cash used in investing activities	8,875	-31,181	-39,572
Financing activities:	'	'	'
Proceeds from repurchase arrangements, net	564,971	404,853	339,046
Payments made on repurchase agreements	-575,916	-378,056	-303,044
Proceeds from other debt	203	1,000	0
Repayments on other debt	-209	-150	-19
Proceeds from Issuance of Preferred Stock and Preference Stock	0	167	0
Net proceeds from common stock issuances	1,803	3,601	4,377
Payments made on common stock repurchases	-856	-77	0
Stock Repurchased During Period, Value	-856	-77	'
Cash dividends paid	-1,659	-1,415	-664
Net cash provided by financing activities	-11,663	29,923	39,696
Net change in cash and cash equivalents	-287	1,063	1,194
Cash and cash equivalents at beginning of period	2,430	1,367	173
Cash and cash equivalents at end of period	2,143	2,430	1,367
Interest Paid	347	256	202
Taxes Paid	$25	$10	$0

Organization

Organization	12 Months Ended
	Dec. 31, 2013
Organization [Abstract]	'
Organization	'
	Organization
	We were organized in Delaware on January 7, 2008, and commenced operations on May 20, 2008 following the completion of our initial public offering ("IPO"). Our common stock is traded on The NASDAQ Global Select Market under the symbol "AGNC".
	We are externally managed by American Capital AGNC Management, LLC (our "Manager"), an affiliate of American Capital, Ltd. ("American Capital").
	We operate so as to qualify to be taxed as a real estate investment trust ("REIT") under the Internal Revenue Code of 1986, as amended (the "Internal Revenue Code"). As a REIT, we are required to distribute annually 90% of our taxable net income. As long as we continue to qualify as a REIT, we will generally not be subject to U.S. federal or state corporate taxes on our taxable net income to the extent that we distribute all of our annual taxable net income to our stockholders. It is our intention to distribute 100% of our taxable net income, after application of available tax attributes, within the limits prescribed by the Internal Revenue Code, which may extend into the subsequent taxable year.
	We earn income primarily from investing on a leveraged basis in agency mortgage-backed securities ("agency MBS"). These investments consist of residential mortgage pass-through securities and collateralized mortgage obligations ("CMOs") for which the principal and interest payments are guaranteed by a government-sponsored enterprise, such as the Federal National Mortgage Association ("Fannie Mae") and the Federal Home Loan Mortgage Corporation ("Freddie Mac"), or by a U.S. Government agency, such as the Government National Mortgage Association ("Ginnie Mae") (collectively referred to as "GSEs"). We may also invest in agency debenture securities issued by Freddie Mac, Fannie Mae or the Federal Home Loan Bank ("FHLB") and in other assets reasonably related to agency securities.
	Our principal objective is to preserve our net asset value (also referred to as "net book value", "NAV" and "stockholders' equity") while generating attractive risk-adjusted returns for distribution to our stockholders through regular quarterly dividends from the combination of our net interest income and net realized gains and losses on our investments and hedging activities. We fund our investments primarily through short-term borrowings structured as repurchase agreements.

Summary_of_Significant_Account

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2013
Accounting Policies [Abstract]	'
Summary of Significant Accounting Policies	'
	Summary of Significant Accounting Policies
	Basis of Presentation and Consolidation
	Our consolidated financial statements are prepared in accordance with accounting principles generally accepted in the United States ("GAAP").
	Our consolidated financial statements include the accounts of our wholly-owned subsidiary, American Capital Agency TRS, LLC, and variable interest entities for which we are the primary beneficiary. Significant intercompany accounts and transactions have been eliminated.
	Use of Estimates
	The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities at the date of the financial statements and revenues and expenses during the period reported. Actual results could differ from those estimates.
	Earnings per Share
	Basic earnings per share ("EPS") is computed by dividing net income by the weighted average number of common shares outstanding during the period. Diluted EPS assumes the conversion, exercise or issuance of all potential common stock equivalents unless the effect is to reduce a loss or increase the income per share.
	Accumulated Other Comprehensive Income (Loss)
	Accounting Standards Codification ("ASC") Topic 220, Comprehensive Income ("ASC 220"), divides comprehensive income into net income and other comprehensive income (loss) ("OCI"), which includes unrealized gains and losses on securities classified as available-for-sale and unrealized gains and losses on derivative financial instruments that are designated and qualify for cash flow hedge accounting under ASC Topic 815, Derivatives and Hedging ("ASC 815"). During fiscal year 2011, we discontinued designating our derivative financial instruments, principally interest rate swaps, as cash flow hedges. See Derivatives Instruments below and Note 5 for further information regarding our discontinuation of cash flow hedge accounting.
	Cash and Cash Equivalents
	Cash and cash equivalents consist of unrestricted demand deposits and highly liquid investments with original maturities of three months or less. Cash and cash equivalents are carried at cost, which approximates fair value.
	Restricted Cash
	Restricted cash includes cash pledged as collateral for clearing and executing trades, repurchase agreements, interest rate swaps and other derivative instruments. Restricted cash is carried at cost, which approximates fair value.
	Investment Securities
	ASC Topic 320, Investments—Debt and Equity Securities ("ASC 320"), requires that at the time of purchase, we designate a security as held-to-maturity, available-for-sale or trading, depending on our ability and intent to hold such security to maturity. Securities classified as trading and available-for-sale are reported at fair value, while securities classified as held-to-maturity are reported at amortized cost. We may, from time to time, sell any of our agency securities as part of our overall management of our investment portfolio. Accordingly, we typically designate our agency securities as available-for-sale. All securities classified as available-for-sale are reported at fair value, with unrealized gains and losses reported in accumulated OCI, a separate component of stockholders' equity. Upon the sale of a security, we determine the cost of the security and the amount of unrealized gains or losses to reclassify out of accumulated OCI into earnings based on the specific identification method.
	Interest-only securities and inverse interest-only securities (collectively referred to as "interest-only securities") represent our right to receive a specified proportion of the contractual interest flows of specific agency CMO securities. Principal-only securities represent our right to receive the contractual principal flows of specific agency CMO securities. Interest-only and principal-only securities are measured at fair value through earnings in gain (loss) on derivative instruments and other securities, net in our consolidated statements of comprehensive income. Our investments in interest-only and principal-only securities are included in agency securities, at fair value on the accompanying consolidated balance sheets.
	REIT equity securities represent investments in the common stock of other publicly traded mortgage REITs that invest predominantly in agency MBS. We designate our investments in REIT equity securities as trading securities and report them at fair value on the accompanying consolidated balance sheets.
	We estimate the fair value of our agency securities based on a market approach using "Level 2" inputs from third-party pricing services and non-binding dealer quotes derived from common market pricing methods. Such methods incorporate, but are not limited to, reported trades and executable bid and asked prices for similar securities, benchmark interest rate curves, such as the spread to the U.S. Treasury rate and interest rate swap curves, convexity, duration and the underlying characteristics of the particular security, including coupon, periodic and life caps, rate reset period, issuer, additional credit support and expected life of the security. We estimate the fair value of our REIT equity securities on a market approach using "Level 1" inputs based on quoted market prices. Refer to Note 7 for further discussion of fair value measurements.
	We evaluate our agency securities for other-than-temporary impairment ("OTTI") on at least a quarterly basis. The determination of whether a security is other-than-temporarily impaired may involve judgments and assumptions based on subjective and objective factors. When a security is impaired, an OTTI is considered to have occurred if any one of the following three conditions exist as of the financial reporting date: (i) we intend to sell the security (that is, a decision has been made to sell the security), (ii) it is more likely than not that we will be required to sell the security before recovery of its amortized cost basis or (iii) we do not expect to recover the security's amortized cost basis, even if we do not intend to sell the security and it is not more likely than not that we will be required to sell the security. A general allowance for unidentified impairments in a portfolio of securities is not permitted.
	If either of the first two conditions exists as of the financial reporting date, the entire amount of the impairment loss, if any, is recognized in earnings as a realized loss and the cost basis of the security is adjusted to its fair value. If the third condition exists, the OTTI is separated into (i) the amount relating to credit loss (the "credit component") and (ii) the amount relating to all other factors (the "non-credit components"). Only the credit component is recognized in earnings, with the non-credit components recognized in OCI. However, in evaluating if the third condition exists, our investments in agency securities typically would not have a credit component since the principal and interest are guaranteed by a GSE and, therefore, any unrealized loss is not the result of a credit loss. In addition, since we designate our agency securities as available-for-sale securities with unrealized gains and losses recognized in OCI, any impairment loss for non-credit components is already recognized in OCI.
	The liquidity of the agency securities market allows us to obtain competitive bids and execute on a sale transaction typically within a day of making the decision to sell a security and, therefore, we generally do not make decisions to sell specific agency securities until shortly prior to initiating a sell order. In some instances, we may sell specific agency securities by delivering such securities into existing short to-be-announced ("TBA") contracts. TBA market conventions require the identification of the specific securities to be delivered no later than 48 hours prior to settlement. If we settle a short TBA contract through the delivery of securities, we will generally identify the specific securities to be delivered within one to two days of the 48-hour deadline.
	We did not recognize any OTTI charges on our investment securities for fiscal years 2013, 2012 and 2011.
	Interest Income
	Interest income is accrued based on the outstanding principal amount of the investment securities and their contractual terms. Premiums or discounts associated with the purchase of investment securities are amortized or accreted into interest income, respectively, over the projected lives of the securities, including contractual payments and estimated prepayments using the interest method in accordance with ASC Subtopic 310-20, Receivables—Nonrefundable Fees and Other Costs ("ASC 310-20").
	We estimate long-term prepayment speeds of our agency securities using a third-party service and market data. The third-party service estimates prepayment speeds using models that incorporate the forward yield curve, current mortgage rates and mortgage rates of the outstanding loans, age and size of the outstanding loans, loan-to-value ratios, volatility and other factors. We review the prepayment speeds estimated by the third-party service and compare the results to market consensus prepayment speeds, if available. We also consider historical prepayment speeds and current market conditions to validate the reasonableness of the prepayment speeds estimated by the third-party service and, based on our Manager's judgment, we may make adjustments to its estimates. Actual and anticipated prepayment experience is reviewed quarterly and effective yields are recalculated when differences arise between (i) our previously estimated future prepayments and (ii) the actual prepayments to date plus our currently estimated future prepayments. If the actual and estimated future prepayment experience differs from our prior estimate of prepayments, we are required to record an adjustment in the current period to the amortization or accretion of premiums and discounts for the cumulative difference in the effective yield through the reporting date.
	Repurchase Agreements
	We finance the acquisition of securities for our investment portfolio through repurchase transactions under master repurchase agreements. Pursuant to ASC Topic 860, Transfers and Servicing ("ASC 860"), we account for repurchase transactions as collateralized financing transactions, which are carried at their contractual amounts (cost), plus accrued interest, as specified in the respective transactions. Our repurchase agreements have maturities of generally less than one year, but may extend up to five years or more. Interest rates under our repurchase agreements generally correspond to one, three or six month LIBOR plus or minus a fixed spread. The fair value of our repurchase agreements is assumed to equal cost as the interest rates are considered to be at market.
	Reverse Repurchase Agreements and Obligation to Return Securities Borrowed under Reverse Repurchase Agreements
	We from time to time borrow securities to cover short sales of U.S. Treasury securities through reverse repurchase transactions under our master repurchase agreements (see Derivatives Instruments below). We account for these as securities borrowing transactions and recognize an obligation to return the borrowed securities at fair value on the balance sheet based on the value of the underlying borrowed securities as of the reporting date. Our reverse repurchase agreements generally mature daily. The fair value of our reverse repurchase agreements is assumed to equal cost as the interest rates are reset daily.
	Manager Compensation
	Our management agreement provides for the payment to our Manager of a management fee and reimbursement of certain operating expenses, which are accrued and expensed during the period for which they are earned or incurred. Refer to Note 8 for the terms of our management agreement and the administrative services agreement between American Capital and our Manager.
	Derivative Instruments
	We use a variety of derivative instruments to hedge a portion of our exposure to market risks, including interest rate risk, prepayment risk and extension risk. The objective of our risk management strategy is to reduce fluctuations in net book value over a range of interest rate scenarios. In particular, we attempt to mitigate the risk of the cost of our variable rate liabilities increasing during a period of rising interest rates. The principal instruments that we use are interest rate swaps and options to enter into interest rate swaps ("interest rate swaptions"). We also utilize forward contracts for the purchase or sale of agency MBS securities on a generic pool, or a TBA contract, basis and on a non-generic, specified pool basis, and we utilize U.S. Treasury securities and U.S. Treasury futures contracts, primarily through short sales. We may also purchase or write put or call options on TBA securities and we may invest in other types of mortgage derivatives, such as interest and principal-only securities, and synthetic total return swaps, such as the Markit IOS Synthetic Total Return Swap Index ("Markit IOS Index").
	We may also enter into TBA contracts as a means of investing in and financing agency securities (thereby increasing our "at risk" leverage) or as a means of disposing of or reducing our exposure to agency securities (thereby reducing our "at risk" leverage). Pursuant to TBA contracts, we agree to purchase or sell, for future delivery, agency securities with certain principal and interest terms and certain types of collateral, but the particular agency securities to be delivered are not identified until shortly before the TBA settlement date. We also may choose, prior to settlement, to move the settlement of these securities out to a later date by entering into an offsetting short or long position (referred to as a "pair off"), net settling the paired off positions for cash, and simultaneously purchasing or selling a similar TBA contract for a later settlement date. This transaction is commonly referred to as a "dollar roll." The agency securities purchased or sold for a forward settlement date are typically priced at a discount to agency securities for settlement in the current month. This difference (or discount) is referred to as the "price drop." The price drop is the economic equivalent of net interest carry income on the underlying agency securities over the roll period (interest income less implied financing cost) and is commonly referred to as "dollar roll income/loss." Consequently, forward purchases of agency securities and dollar roll transactions represent a form of off-balance sheet financing.
	We account for derivative instruments in accordance with ASC Topic 815, Derivatives and Hedging ("ASC 815"). ASC 815 requires an entity to recognize all derivatives as either assets or liabilities in the balance sheet and to measure those instruments at fair value.
	Our derivative agreements generally contain provisions that allow for netting or setting off derivative assets and liabilities with each counterparty; however, we report related assets and liabilities on a gross basis in our consolidated balance sheets. Derivative instruments in a gain position are reported as derivative assets at fair value and derivative instruments in a loss position are reported as derivative liabilities at fair value in our consolidated balance sheets. Changes in fair value of derivative instruments and periodic settlements related to our derivative instruments are recorded in gain (loss) on derivative instruments and other securities, net in our consolidated statements of comprehensive income. Cash receipts and payments related to derivative instruments are classified in our consolidated statements of cash flows according to the underlying nature or purpose of the derivative transaction, generally in the investing section.
	The use of derivatives creates exposure to credit risk relating to potential losses that could be recognized in the event that the counterparties to these instruments fail to perform their obligations under the contracts. We attempt to minimize this risk by limiting our counterparties to major financial institutions with acceptable credit ratings, monitoring positions with individual counterparties and adjusting posted collateral as required.
	Discontinuation of hedge accounting for interest rate swap agreements
	Prior to September 30, 2011, we entered into interest rate swap agreements typically with the intention of qualifying for hedge accounting under ASC 815. However, as of September 30, 2011, we elected to discontinue hedge accounting for our interest rate swaps. Upon discontinuation of hedge accounting, the net deferred loss related to our de-designated interest rate swaps remained in accumulated OCI and is being reclassified from accumulated OCI into interest expense on a straight-line basis over the remaining term of each interest rate swap.
	Interest rate swap agreements
	We use interest rate swaps to hedge the variable cash flows associated with borrowings made under our repurchase agreement facilities. Under our interest rate swap agreements, we typically pay a fixed rate and receive a floating rate based on one, three or six-month LIBOR ("payer swaps") with terms up to 20 years. The floating rate we receive under our swap agreements has the effect of offsetting the repricing characteristics of our repurchase agreements and cash flows on such liabilities. Our swap agreements are privately negotiated in the over−the−counter ("OTC") market and may be centrally cleared through a registered commodities exchange ("centrally cleared swaps").
	We estimate the fair value of our centrally cleared interest rate swaps using the daily settlement price determined by the respective exchange. Centrally cleared swaps are valued by the exchange using a pricing model that references the underlying rates including the overnight index swap rate and LIBOR forward rate to produce the daily settlement price.
	We estimate the fair value of our "non-centrally cleared" swaps using a combination of inputs from counterparty and third-party pricing models to estimate the net present value of the future cash flows using a forward interest rate yield curve in effect as of the end of the measurement period. We also incorporate both our own and our counterparties' nonperformance risk in estimating the fair value of our interest rate swaps. In considering the effect of nonperformance risk, we consider the impact of netting and credit enhancements, such as collateral postings and guarantees, and have concluded that our own and our counterparty risk is not significant to the overall valuation of these agreements.
	Interest rate swaptions
	We purchase interest rate swaptions to help mitigate the potential impact of larger increases or decreases in interest rates on the performance of our investment portfolio (referred to as "convexity risk"). The interest rate swaptions provide us the option to enter into an interest rate swap agreement for a predetermined notional amount, stated term and pay and receive interest rates in the future. Our swaption agreements typically provide us the option to enter into a pay fixed rate interest rate swap, which we refer as "payer swaptions." We may also enter into swaption agreements that provide us the option to enter into a receive fixed interest rate swap, which we refer to as "receiver swaptions." The premium paid for interest rate swaptions is reported as an asset in our consolidated balance sheets. The premium is valued at an amount equal to the fair value of the swaption that would have the effect of closing the position adjusted for nonperformance risk, if any. The difference between the premium and the fair value of the swaption is reported in gain (loss) on derivative instruments and other securities, net in our consolidated statements of comprehensive income. If a swaption expires unexercised, the realized loss on the swaption would be equal to the premium paid. If we sell or exercise a swaption, the realized gain or loss on the swaption would be equal to the difference between the cash or the fair value of the underlying interest rate swap received and the premium paid.
	Our interest rates swaption agreements are privately negotiated in the OTC market and are not subject to central clearing. We estimate the fair value of interest rate swaptions using a combination of inputs from counterparty and third-party pricing models based on the fair value of the future interest rate swap that we have the option to enter into as well as the remaining length of time that we have to exercise the option, adjusted for non-performance risk, if any.
	TBA securities
	A TBA security is a forward contract for the purchase ("long position") or sale ("short position") of agency MBS at a predetermined price, face amount, issuer, coupon and stated maturity on an agreed-upon future date. The specific agency MBS delivered into the contract upon the settlement date, published each month by the Securities Industry and Financial Markets Association, are not known at the time of the transaction. We may enter into TBA contracts as a means of hedging against short-term changes in interest rates. We may also enter into TBA contracts as a means of acquiring or disposing of agency securities and we may from time to time utilize TBA dollar roll transactions to finance agency MBS purchases.
	We account for TBA contracts as derivative instruments since we cannot assert that it is probable at inception and throughout the term of the TBA contract that we will take physical delivery of the agency security upon settlement of the contract. We account for TBA dollar roll transactions as a series of derivative transactions. Gains, losses and dollar roll income associated with our TBA contracts and dollar roll transactions are recognized in our consolidated statements of comprehensive income in gain (loss) on derivative instruments and other securities, net.
	We estimate the fair value of TBA securities based on similar methods used to value our agency MBS securities.
	Forward commitments to purchase or sell specified agency MBS
	We enter into forward commitments to purchase or sell specified agency MBS from time to time as a means of acquiring assets or as a hedge against short-term changes in interest rates. Such forward commitments typically require physical settlement. We account for such forward commitments as derivatives if the delivery of the specified agency MBS and settlement extend beyond established market conventions. Realized and unrealized gains and losses associated with forward commitments accounted for as derivatives are recognized in our consolidated statements of comprehensive income in gain (loss) on derivative instruments and other securities, net.
	We estimate the fair value of forward commitments to purchase or sell specified agency MBS based on similar methods used to value agency MBS, as well as the remaining length of time of the forward commitment.
	U.S. Treasury securities
	We purchase or sell short U.S. Treasury securities and U.S. Treasury futures contracts to help mitigate the potential impact of changes in interest rates on the performance of our portfolio. Gains and losses associated with purchases and short sales of U.S. Treasury securities and U.S. Treasury futures contracts are recognized in gain (loss) on derivative instruments and other securities, net in our consolidated statements of comprehensive income.
	Variable Interest Entities
	ASC Topic 810, Consolidation ("ASC 810"), requires an enterprise to consolidate a variable interest entity ("VIE") if it is deemed the primary beneficiary of the VIE. Further, ASC 810 requires a qualitative assessment to determine the primary beneficiary of a VIE and ongoing assessments of whether an enterprise is the primary beneficiary of a VIE as well as additional disclosures for entities that have variable interests in VIEs.
	We have entered into transactions involving CMO trusts, which are VIEs. We will consolidate a CMO trust if we are the CMO trust's primary beneficiary; that is, if we have a variable interest that provides us with a controlling financial interest in the CMO trust. An entity is deemed to have a controlling financial interest if the entity has the power to direct the activities of a VIE that most significantly impact the VIE's economic performance and the obligation to absorb losses of or right to receive benefits from the VIE that could potentially be significant to the VIE. As part of the qualitative assessment in determining if we have a controlling financial interest, we evaluate whether we control the selection of financial assets transferred to the CMO trust. For each of our consolidated CMO trusts we controlled the selection of the agency MBS transferred from our investment portfolio to an investment bank in exchange for cash proceeds and at the same time entered into a commitment with the investment bank to purchase to-be-issued securities collateralized by the agency MBS transferred, which resulted in our consolidation of the CMO trusts.
	Agency MBS transferred to consolidated VIEs are reported on our consolidated balance sheets in agency securities transferred to consolidated VIEs, at fair value and can only be used to settle the obligations of each respective VIE.
	We report debt issued in connection with the CMO trusts on our consolidated balance sheets in debt of consolidated VIEs, at fair value, which represents tranches within the trusts sold to third-parties and excludes tranches acquired by us that eliminate upon consolidation. The third-party beneficial interest holders in the VIEs have no recourse against our general credit. We elected the option to account for the consolidated debt at fair value, with changes in fair value reflected in earnings during the period in which they occur, because we believe this election more appropriately reflects our financial position as both the consolidated assets and consolidated debt are presented in a consistent manner on our consolidated balance sheets. We estimate the fair value of the consolidated debt based on a market approach using "Level 2" inputs from third-party pricing services and dealer quotes.
	Income Taxes
	We elected to be taxed as a REIT under the provisions of the Internal Revenue Code and the corresponding provisions of state law, commencing with our initial tax year ended December 31, 2008. In order to qualify as a REIT, we must annually distribute, in a timely manner to our stockholders, at least 90% of our taxable ordinary income. A REIT is not subject to tax on its earnings to the extent that it distributes its annual taxable income to its stockholders and as long as certain asset, income and stock ownership tests are met. We operate in a manner that will allow us to be taxed as a REIT. As permitted by the Internal Revenue Code, a REIT can designate dividends paid in the subsequent year as dividends of the current year if those dividends are both declared by the extended due date of the REIT's federal income tax return and paid to stockholders by the last day of the subsequent year.
As a REIT, if we fail to distribute in any calendar year at least the sum of (i) 85% of our ordinary income for such year, (ii) 95% of our capital gain net income for such year and (iii) any undistributed taxable income from the prior year, we are subject to a non-deductible 4% excise tax on the excess of such required distribution over the sum of (a) the amounts actually distributed and, if applicable, (b) the amounts of income we retained and on which we have paid corporate income tax. Dividends declared by December 31 and paid by January 31 are treated as having been a distribution of our taxable income for the prior tax year.
We and our domestic subsidiary, American Capital Agency TRS, LLC, have made a joint election to treat our subsidiary as a taxable REIT subsidiary. As such, American Capital Agency TRS, LLC, is subject to federal and state income tax.
We evaluate uncertain income tax positions, if any, in accordance with ASC Topic 740, Income Taxes ("ASC 740"). To the extent we incur interest and/or penalties in connection with our tax obligations, such amounts shall be classified as income tax expense on our consolidated statements of operations.
Reclassifications
Certain prior period amounts in the consolidated financial statements have been reclassified to conform to the current period presentation.

Investment_Securities

Investment Securities	12 Months Ended
	Dec. 31, 2013
Available-for-sale Securities [Abstract]	'
Investment Securities	'
	Investment Securities
	As of December 31, 2013, we had agency MBS of $65.9 billion at fair value, with a total cost basis of $67.0 billion. The net unamortized premium balance on our agency MBS as of December 31, 2013 was $3.0 billion, including interest and principal-only strips. The following tables summarize our investments in agency MBS as of December 31, 2013 (dollars in millions):
			31-Dec-13
	Agency MBS		Fannie Mae			Freddie Mac				Ginnie Mae				Total
	Available-for-sale agency MBS:
	Agency MBS, par		$	50,914		$	12,640			$	223			$	63,777
	Unamortized discount		(25		)	(7		)		—				(32		)
	Unamortized premium		2,210			631				7				2,848
	Amortized cost		53,099			13,264				230				66,593
	Gross unrealized gains		181			74				5				260
	Gross unrealized losses		(991		)	(358		)		—				(1,349		)
	Total available-for-sale agency MBS, at fair value		52,289			12,980				235				65,504
	Agency MBS remeasured at fair value through earnings:
	Interest-only and principal-only strips, amortized cost 1		400			32				—				432
	Gross unrealized gains		13			3				—				16
	Gross unrealized losses		(9		)	(2		)		—				(11		)
	Total agency MBS remeasured at fair value through earnings		404			33				—				437
	Total agency MBS, at fair value		$	52,693		$	13,013			$	235			$	65,941
	Weighted average coupon as of December 31, 2013 2		3.53		%	3.78		%		3.56		%		3.58		%
	Weighted average yield as of December 31, 2013 3		2.66		%	2.87		%		1.66		%		2.7		%
	Weighted average yield for the year ended December 31, 2013 3		2.74		%	2.87		%		1.79		%		2.77		%
	________________________
	1	The underlying unamortized principal balance ("UPB" or "par value") of our interest-only agency MBS strips was $1.4 billion and the weighted average contractual interest we are entitled to receive was 5.50% of this amount as of December 31, 2013. The par value of our principal-only agency MBS strips was $271 million as of December 31, 2013.
	2	The weighted average coupon includes the interest cash flows from our interest-only agency MBS strips taken together with the interest cash flows from our fixed-rate, adjustable-rate and CMO agency MBS as a percentage of the par value of our agency MBS (excluding the UPB of our interest-only securities) as of December 31, 2013.
	3	Incorporates a weighted average future constant prepayment rate assumption of 7% based on forward rates as of December 31, 2013.
			31-Dec-13
	Agency MBS		Amortized			Gross				Gross				Fair Value
			Cost			Unrealized				Unrealized
						Gain				Loss
	Fixed-Rate		$	64,057		$	242			$	(1,338	)		$	62,961
	Adjustable-Rate		1,223			15				(3		)		1,235
	CMO		1,313			3				(8		)		1,308
	Interest-only and principal-only strips		432			16				(11		)		437
	Total agency MBS		$	67,025		$	276			$	(1,360	)		$	65,941
	As of December 31, 2012, we had agency MBS of $85.2 billion at fair value, with a total cost basis of $83.2 billion. The net unamortized premium balance on our agency MBS as of December 31, 2012 was $4.4 billion, including interest and principal-only strips. The following tables summarize our investments in agency MBS as of December 31, 2012 (dollars in millions):
			December 31, 2012
	Agency MBS		Fannie Mae			Freddie Mac				Ginnie Mae				Total
	Available-for-sale agency MBS:
	Agency MBS, par		$	58,912		$	19,336			$	238			$	78,486
	Unamortized premium		3,208			948				10				4,166
	Amortized cost		62,120			20,284				248				82,652
	Gross unrealized gains		1,585			481				6				2,072
	Gross unrealized losses		(18		)	(7		)		—				(25		)
	Total available-for-sale agency MBS, at fair value		63,687			20,758				254				84,699
	Agency MBS remeasured at fair value through earnings:
	Interest-only and principal-only strips, amortized cost 1		486			55				—				541
	Gross unrealized gains		26			1				—				27
	Gross unrealized losses		(9		)	(13		)		—				(22		)
	Total agency MBS remeasured at fair value through earnings		503			43				—				546
	Total agency MBS, at fair value		$	64,190		$	20,801			$	254			$	85,245
	Weighted average coupon as of December 31, 2012 2		3.7		%	3.67		%		3.77		%		3.69		%
	Weighted average yield as of December 31, 2012 3		2.62		%	2.61		%		1.6		%		2.61		%
	Weighted average yield for the year ended December 31, 2012 3		2.83		%	2.83		%		1.63		%		2.82		%
	________________________
	1	The UPB of our interest-only securities was $1.7 billion and the weighted average contractual interest we are entitled to receive was 5.78% of this amount as of December 31, 2012. The par value of our principal-only agency MBS strips was $302 million as of December 31, 2012.
	2	The weighted average coupon includes the interest cash flows from our interest-only securities taken together with the interest cash flows from our fixed-rate, adjustable-rate and CMO securities as a percentage of the par value of our agency securities (excluding the UPB of our interest-only securities) as of December 31, 2012.
	3	Incorporates a weighted average future constant prepayment rate assumption of 11% based on forward rates as of December 31, 2012.
			December 31, 2012
	Agency MBS		Amortized			Gross				Gross				Fair Value
			Cost			Unrealized				Unrealized
						Gain				Loss
	Fixed-Rate		$	81,617		$	2,043			$	(25	)		$	83,635
	Adjustable-Rate		865			26				—				891
CMO		170			3				—				173
Interest-only and principal-only strips		541			27				(22		)		546
Total agency MBS		$	83,193		$	2,099			$	(47	)		$	85,245
As of December 31, 2013 and 2012, we did not have investments in agency debenture securities.
The actual maturities of our agency MBS are generally shorter than the stated contractual maturities. Actual maturities are affected by the contractual lives of the underlying mortgages, periodic contractual principal payments and principal prepayments. As of December 31, 2013 and 2012, our weighted average expected constant prepayment rate ("CPR") over the remaining life of our aggregate agency MBS portfolio was 7% and 11%, respectively. Our estimates differ materially for different types of securities and thus individual holdings have a wide range of projected CPRs. We estimate long-term prepayment assumptions for different securities using a third-party service and market data. The third-party service estimates prepayment speeds using models that incorporate the forward yield curve, current mortgage rates and mortgage rates of the outstanding loans, age and size of the outstanding loans, loan-to-value ratios, volatility and other factors. We review the prepayment speeds estimated by the third-party service and compare the results to market consensus prepayment speeds, if available. We also consider historical prepayment speeds and current market conditions to validate reasonableness. As market conditions may change rapidly, we may make adjustments for different securities based on our Manager's judgment. Various market participants could use materially different assumptions.
The following table summarizes our agency MBS classified as available-for-sale as of December 31, 2013 and 2012 according to their estimated weighted average life classification (dollars in millions):
		31-Dec-13											December 31, 2012
Estimated Weighted Average Life of Agency MBS Classified as Available-for-Sale 1		Fair Value			Amortized				Weighted		Weighted		Fair Value			Amortized		Weighted		Weighted
					Cost				Average		Average					Cost		Average		Average
									Coupon		Yield							Coupon		Yield
≤ 1 year		$	129		$	129			3.07%		2.53%		$	—		$	—	—%		—%
> 1 year and ≤ 3 years		498			491				4.08%		2.25%		1,119			1,108		4.18%		2.14%
> 3 years and ≤ 5 years		24,471			24,342				3.59%		2.57%		27,448			26,750		3.36%		2.29%
> 5 years and ≤10 years		38,522			39,635				3.39%		2.73%		54,054			52,735		3.69%		2.75%
> 10 years		1,884			1,996				3.66%		2.96%		2,078			2,059		3.44%		2.65%
Total		$	65,504		$	66,593			3.47%		2.68%		$	84,699		$	82,652	3.59%		2.59%
_______________________
1	Excludes interest and principal-only strips.
The weighted average life of our interest-only strips was 6.3 and 5.7 years as of December 31, 2013 and 2012, respectively. The weighted average life of our principal-only strips was 8.6 and 6.4 years as of December 31, 2013 and 2012, respectively.
Our agency securities classified as available-for-sale are reported at fair value, with unrealized gains and losses excluded from earnings and reported in accumulated OCI. The following table summarizes changes in accumulated OCI, a separate component of stockholders' equity, for our available-for-sale securities for fiscal years 2013, 2012 and 2011 (in millions):
Agency Securities Classified as		Beginning Accumulated OCI			Unrealized			Reversal of			Ending
Available-for-Sale		Balance			Gains and (Losses), Net			Unrealized			Accumulated OCI
								(Gains) and Losses,			Balance
								Net on Realization
Fiscal year 2013		$	2,040		(4,535	)		1,408			$	(1,087	)
Fiscal year 2012		$	1,001		2,235			(1,196	)		$	2,040
Fiscal year 2011		$	(28	)	1,512			(483	)		$	1,001
The following table presents the gross unrealized loss and fair values of our available-for-sale agency securities by length of time that such securities have been in a continuous unrealized loss position as of December 31, 2013 and 2012 (in millions):
		Unrealized Loss Position For
		Less than 12 Months							12 Months or More							Total
Agency Securities Classified as		Estimated Fair			Unrealized				Estimated				Unrealized			Estimated Fair		Unrealized
Available-for-Sale		Value			Loss				Fair Value				Loss			Value		Loss
December 31, 2013		$	42,853		$	(1,248	)		$	1,586			$	(101	)	$	44,439	$	(1,349	)
December 31, 2012		$	8,430		$	(25	)		$	—			$	—		$	8,430	$	(25	)
As of December 31, 2013 and 2012, a decision had not been made to sell any of these agency securities and we do not believe it is more likely than not we will be required to sell the agency securities before recovery of their amortized cost basis. The unrealized losses on these agency securities are not due to credit losses given the GSE guarantees, but are rather due to changes in interest rates and prepayment expectations. Accordingly, we did not recognize any OTTI charges on our investment securities for fiscal years 2013 and 2012. However, as we continue to actively manage our portfolio, we may recognize additional realized losses on our agency securities upon selecting specific securities to sell.
Gains and Losses
The following table is a summary of our net gain (loss) from the sale of agency securities classified as available-for-sale for fiscal years 2013, 2012 and 2011 (in millions):
		Fiscal Year
Agency Securities Classified as		2013			2012				2011
Available-for-Sale
Agency MBS sold, at cost		$	(81,516	)	$	(63,610	)		$	(37,579	)
Proceeds from agency MBS sold 1		80,108			64,806				38,052
Net (loss) gain on sale of agency MBS		$	(1,408	)	$	1,196			$	473
Gross gain on sale of agency MBS		$	217		$	1,209			$	510
Gross loss on sale of agency MBS		(1,625		)	(13		)		(37		)
Net (loss) gain on sale of agency MBS		$	(1,408	)	$	1,196			$	473
________________________
1	Proceeds include cash received during the period, plus receivable for agency MBS sold during the period as of period end.
For fiscal years 2012 and 2011, we recognized a net unrealized gain of $17 million and a net unrealized loss of $16 million, respectively, for the change in value of investments in interest and principal-only strips in gain (loss) on derivative instruments and other securities, net in our consolidated statements of comprehensive income. For fiscal year 2013, we did not recognize a net unrealized gain or loss on our interest and principal-only investments. For fiscal year 2011, we recognized a net realized loss of $10 million for the sale of interest and principal-only strips in gain (loss) on sale of agency securities, net in our consolidated statements of comprehensive income. There were no sales of interest and principal-only strips during fiscal years 2013 and 2012.
Pledged Assets
The following tables summarize our assets pledged as collateral under repurchase agreements, debt of consolidated VIEs, derivative agreements and prime broker agreements by type, including securities pledged related to securities sold but not yet settled, as of December 31, 2013 and 2012 (in millions):
		December 31, 2013
Assets Pledged		Repurchase Agreements			Debt of Consolidated VIEs				Derivative Agreements				Prime Broker Agreements			Total
Agency MBS - fair value		$	62,708		$	1,459			$	28			$	91		$	64,286
U.S. Treasury securities - fair value		3,708			—				70				—			3,778
Accrued interest on pledged securities		189			5				1				—			195
Restricted cash		3			—				41				57			101
Total		$	66,608		$	1,464			$	140			$	148		$	68,360
		December 31, 2012
Assets Pledged		Repurchase Agreements			Debt of Consolidated VIEs				Derivative Agreements				Prime Broker Agreements			Total
Agency MBS - fair value		$	78,400		$	1,535			$	1,065			$	501		$	81,501
Accrued interest on pledged securities		217			5				3				1			226
Restricted cash		—			—				249				150			399
Total		$	78,617		$	1,540			$	1,317			$	652		$	82,126
In addition, as of December 31, 2013, we had $82 million of agency MBS, $164 million of U.S. Treasury securities and $366 million of cash pledged to use (at fair value) as collateral for our derivative agreements. As of December 31, 2012, we had $249 million of cash pledged to use as collateral for our derivative agreements.
The following table summarizes our securities pledged as collateral under repurchase agreements and debt of consolidated VIEs by remaining maturity, including securities pledged related to sold but not yet settled securities, as of December 31, 2013 and 2012 (in millions):
		December 31, 2013											December 31, 2012
Agency Securities Pledged by Remaining Maturity of Repurchase Agreements and Debt of Consolidated VIEs		Fair Value of Pledged Securities			Amortized				Accrued				Fair Value of Pledged Securities			Amortized		Accrued
					Cost of Pledged Securities				Interest on							Cost of Pledged Securities		Interest on
									Pledged									Pledged
									Securities									Securities
Agency MBS:
≤ 30 days		$	27,694		$	28,125			$	76			$	29,284		$	28,525	$	82
> 30 and ≤ 60 days		14,955			15,210				42				21,716			21,251		58
> 60 and ≤ 90 days		10,117			10,290				28				16,188			15,780		45
> 90 days		11,401			11,623				32				12,747			12,447		37
Total agency MBS		64,167			65,248				178				79,935			78,003		222
U.S. Treasury securities:
1 day		3,708			3,760				16				—			—		—
Total		$	67,875		$	69,008			$	194			$	79,935		$	78,003	$	222
As of December 31, 2013 and 2012, none of our repurchase agreement borrowings backed by agency MBS were due on demand or mature overnight.
Securitizations and Variable Interest Entities
As of December 31, 2013 and 2012, we held investments in CMO trusts, which are VIEs. We have consolidated certain of these CMO trusts in our consolidated financial statements where we have determined we are the primary beneficiary of the trusts. All of our CMO securities are backed by fixed or adjustable-rate agency MBS. Fannie Mae or Freddie Mac guarantees the payment of interest and principal and acts as the trustee and administrator of their respective securitization trusts. Accordingly, we are not required to provide the beneficial interest holders of the CMO securities any financial or other support. Our maximum exposure to loss related to our involvement with CMO trusts is the fair value of the CMO securities and interest and principal-only securities held by us, less principal amounts guaranteed by Fannie Mae and Freddie Mac.
In connection with our consolidated CMO trusts, we recognized agency securities with a total fair value of $1.5 billion as of December 31, 2013 and 2012 and debt, at fair value, of $910 million and $937 million, respectively, in our accompanying consolidated balance sheets. As of December 31, 2013 and 2012, such agency securities had an aggregate unpaid principal balance of $1.4 billion and such debt had an aggregate unpaid principal balance of $900 million and $908 million, respectively. We re-measure our consolidated debt at fair value through earnings in gain (loss) on derivative instruments and other securities, net in our consolidated statements of comprehensive income. For fiscal years 2013 and 2012, we recognized a net gain of $39 million and a net loss of $28 million in earnings, respectively, associated with our consolidated debt. We did not recognize any gains or losses during fiscal year 2011. Our involvement with the consolidated trusts is limited to the agency securities transferred by us upon the formation of the trusts and the CMO securities subsequently held by us. There are no arrangements that could require us to provide financial support to the trusts.
As of December 31, 2013 and 2012, the fair value of our CMO securities and interest and principal-only securities, excluding the consolidated CMO trusts discussed above, was $1.7 billion and $719 million, respectively, or $2.3 billion and $1.3 billion, respectively, including the net asset value of our consolidated CMO trusts. Our maximum exposure to loss related to our CMO securities and interest and principal-only securities, including our consolidated CMO trusts, was $246 million and $343 million as of December 31, 2013 and 2012, respectively.

Repurchase_Agreements_And_Othe

Repurchase Agreements And Other Debt	12 Months Ended
	Dec. 31, 2013
Disclosure of Repurchase Agreements [Abstract]	'
Repurchase Agreements And Other Debt	'
	Repurchase Agreements and Other Debt
	We pledge certain of our securities as collateral under repurchase arrangements with financial institutions, the terms and conditions of which are negotiated on a transaction-by-transaction basis. Interest rates on these borrowings are generally based on LIBOR plus or minus a margin and amounts available to be borrowed are dependent upon the fair value of the securities pledged as collateral, which fluctuates with changes in interest rates, type of security and liquidity conditions within the banking, mortgage finance and real estate industries. In response to declines in fair value of pledged securities, lenders may require us to post additional collateral or pay down borrowings to re-establish agreed upon collateral requirements, referred to as margin calls. As of December 31, 2013 and 2012, we have met all margin call requirements.
	The following table summarizes our borrowings under repurchase arrangements and weighted average interest rates classified by remaining maturities as of December 31, 2013 and 2012 (dollars in millions):
		31-Dec-13					December 31, 2012
	Remaining Maturity	Repurchase Agreements		Weighted		Weighted	Repurchase Agreements		Weighted		Weighted
				Average		Average Days			Average		Average Days
				Interest		to Maturity			Interest		to Maturity
				Rate					Rate
	Agency MBS:
	≤ 1 month	$	23,577	0.42	%	15	$	25,474	0.48	%	17
	> 1 to ≤ 3 months	20,490		0.43	%	61	30,402		0.49	%	57
	> 3 to ≤ 6 months	6,946		0.45	%	140	7,208		0.53	%	128
	> 6 to ≤ 9 months	2,232		0.53	%	230	4,509		0.57	%	234
	> 9 to ≤ 12 months	3,607		0.54	%	323	2,149		0.6	%	312
	> 12 to ≤ 24 months	3,261		0.6	%	603	2,142		0.65	%	591
	> 24 to ≤ 36 months	500		0.62	%	930	2,492		0.69	%	1,002
	> 36 months	602		0.68	%	1,468	102		0.73	%	1,751
	Total agency MBS	61,215		0.45	%	124	74,478		0.51	%	118
	U.S. Treasury securities:
	1 day	2,318		0.02	%	1	—		—	%	—
	Total / Weighted Average	$	63,533	0.44	%	119	$	74,478	0.51	%	118
	As of December 31, 2013 and 2012, we did not have an amount at risk with any repurchase agreement counterparty greater than 4% of our stockholders' equity.
	As of December 31, 2013 and 2012, debt of consolidated VIEs, at fair value ("other debt") was $910 million and $937 million, respectively. As of December 31, 2013 and 2012, our other debt had a weighted average interest rate of LIBOR plus 42 and 43 basis points and a principal balance of $900 million and $908 million, respectively. The actual maturities of our other debt are generally shorter than the stated contractual maturities. The actual maturities are affected by the contractual lives of the underlying agency MBS securitizing our other debt and periodic principal prepayments of such underlying securities. The estimated weighted average life of our other debt as of December 31, 2013 was 5.4 years.
	As of December 31, 2013 and 2012, we also had outstanding forward commitments to purchase and sell agency securities, including TBA dollar roll transactions, (see Notes 2 and 5). These transactions represent a form of off-balance sheet financing and serve to either increase, in the case of forward purchases, or decrease, in the case of forward sales, our "at risk" leverage. However, pursuant to ASC 815, we typically account for such transactions as one or more series of derivative transactions and, consequently, they are not included in our on-balance sheet debt or measurement of commensurate leverage ratios.

Derivative_and_Other_Hedging_I

Derivative and Other Hedging Instruments	12 Months Ended
	Dec. 31, 2013
Derivative Asset, Fair Value, Amount Not Offset Against Collateral [Abstract]	'
Derivative and Other Hedging Instruments	'
	Derivative and Other Hedging Instruments
	In connection with our risk management strategy, we hedge a portion of our interest rate risk by entering into derivative and other hedging instrument contracts. We typically enter into agreements for interest rate swaps and interest rate swaptions. We may also purchase or short TBA and U.S. Treasury securities, purchase or write put or call options on TBA securities or we may invest in other types of mortgage derivative securities, such as interest and principal-only securities, and synthetic total return swaps, such as the Markit IOS Index. Our risk management strategy attempts to manage the overall risk of the portfolio, reduce fluctuations in book value and generate additional income distributable to stockholders. For additional information regarding our derivative instruments and our overall risk management strategy, please refer to the discussion of derivative and other hedging instruments in Note 2.
	Prior to September 30, 2011, our interest rate swaps were typically designated as cash flow hedges under ASC 815; however, as of September 30, 2011, we elected to discontinue hedge accounting for our interest rate swaps in order to increase our funding flexibility. For fiscal years 2013 and 2012 and for the period from September 30, 2011 to December 31, 2011, we reclassified $189 million, $205 million and $54 million, respectively, of net deferred losses from accumulated OCI into interest expense related to our de-designated interest rate swaps and recognized an equal, but offsetting, amount in other comprehensive income. Our total net periodic interest costs on our swap portfolio for these periods were $613 million, $457 million and $89 million, respectively. The difference of $424 million, $252 million and $35 million for these periods, respectively, is reported in our accompanying consolidated statements of comprehensive income in gain (loss) on derivative instruments and other securities, net. As of December 31, 2013, the remaining net deferred loss in accumulated OCI related to de-designated interest rate swaps was $296 million and will be reclassified from OCI into interest expense over a remaining weighted average period of 2.1 years. The net deferred loss expected to be reclassified from OCI into interest expense over the next twelve months as of December 31, 2013 was $156 million.
	Derivative Assets (Liabilities), at Fair Value
	The table below summarizes fair value information about our derivative assets and liabilities as of December 31, 2013 and 2012 (in millions):
	Derivatives Instruments		Balance Sheet Location		December 31, 2013				December 31, 2012
	Interest rate swaps		Derivative assets, at fair value		$	880			$	14
	Payer swaptions		Derivative assets, at fair value		258				171
	Purchase of TBA and forward settling agency securities		Derivative assets, at fair value		2				116
	Sale of TBA and forward settling agency securities		Derivative assets, at fair value		15				—
	U.S. Treasury futures - short		Derivative assets, at fair value		39				—
					$	1,194			$	301
	Interest rate swaps		Derivative liabilities, at fair value		$	(400	)		$	(1,243	)
	Purchase of TBA and forward settling agency securities		Derivative liabilities, at fair value		(20		)		(1		)
	Sale of TBA and forward settling agency securities		Derivative liabilities, at fair value		(2		)		(20		)
					$	(422	)		$	(1,264	)
	Additionally, as of December 31, 2013 and 2012, we had obligations to return U.S. Treasury securities borrowed under reverse repurchase agreements accounted for as securities borrowing transactions at a fair value of $1.8 billion and $11.8 billion, respectively. The borrowed securities were used to cover short sales of U.S. Treasury securities from which we received total proceeds of $1.9 billion and $11.7 billion, respectively. The change in fair value of the borrowed securities is recorded in gain (loss) on derivative instruments and other securities, net in our consolidated statements of comprehensive income.
	The following tables summarize our interest rate swap agreements outstanding as of December 31, 2013 and 2012 (dollars in millions):
			31-Dec-13
	Payer Interest Rate Swaps		Notional				Average			Average			Net				Average
			Amount 1				Fixed			Receive			Estimated				Maturity
							Pay Rate 2			Rate 3			Fair Value				(Years) 4
	≤ 3 years		$	16,750			1.57	%		0.19	%		$	(382	)		1.6
	> 3 to ≤ 5 years		10,225				1.07	%		0.24	%		81				3.9
	> 5 to ≤ 7 years		5,700				1.97	%		0.26	%		113				6
	> 7 to ≤ 10 years		8,825				2.28	%		0.24	%		499				8.8
	> 10 years		1,750				2.79	%		0.24	%		169				14.7
	Total Payer Interest Rate Swaps		$	43,250			1.7	%		0.22	%		$	480			4.7
	________________________
	1	Notional amount includes forward starting swaps of $4.0 billion with an average forward start date of 1.9 years from December 31, 2013.
	2	Average fixed pay rate includes forward starting swaps. Excluding forward starting swaps, the average fixed pay rate was 1.57% as of December 31, 2013.
	3	Average receive rate excludes forward starting swaps.
	4	Average maturity measured from December 31, 2013 through stated maturity date.
			December 31, 2012
	Payer Interest Rate Swaps 1		Notional				Average		Average		Net				Average
			Amount				Fixed		Receive		Estimated				Maturity
							Pay Rate		Rate		Fair Value				(Years)
	≤ 3 years		$	14,600			1.23%		0.26%		$	(294	)		2
	> 3 to ≤ 5 years		20,250				1.48%		0.29%		(666		)		4.1
	> 5 to ≤ 7 years		5,600				1.53%		0.34%		(163		)		6.1
	> 7 to ≤ 10 years		5,200				1.89%		0.35%		(113		)		9.2
	> 10 years		1,200				1.79%		0.31%		7				10.2
	Total Payer Interest Rate Swaps		$	46,850			1.46%		0.29%		$	(1,229	)		4.4
	________________________
	1	Amounts include forward starting swaps of $1.7 billion ranging up to four months from December 31, 2012.
	The following tables summarize our interest rate swaption agreements outstanding as of December 31, 2013 and 2012 (dollars in millions):
			December 31, 2013
			Option										Underlying Swap
	Payer Swaptions		Cost				Fair				Average		Notional				Average Fixed Pay		Average		Average
							Value				Months to		Amount				Rate		Receive		Term
											Expiration								Rate		(Years)
																			(LIBOR)
	≤ 1 year		$	193			$	117			4		$	9,400			2.87%		3M		7.8
	> 1 to ≤ 2 years		105				92				19		3,600				3.40%		3M		5.6
	> 2 to ≤ 3 years		35				45				30		1,150				3.81%		3M		5.8
	> 3 to ≤ 5 years		2				4				52		100				4.80%		3M		7
	Total/Wtd Avg		$	335			$258				10		$	14,250			3.09%		3M		7
			December 31, 2012
			Option										Underlying Swap
	Payer Swaptions		Cost				Fair				Average		Notional				Average Fixed Pay		Average		Average
							Value				Months to		Amount				Rate		Receive		Term
											Expiration								Rate		(Years)
																			(LIBOR)
≤ 1 year		$	76			$	15			4		$	5,150			2.65%		1M / 3M		8.6
> 1 to ≤ 2 years		65				34				19		4,050				2.82%		3M		6.7
> 2 to ≤ 3 years		97				87				33		3,900				3.51%		3M		8.6
> 3 to ≤ 4 years		12				11				46		450				3.20%		3M		6.1
> 4 to ≤ 5 years		24				24				59		900				3.33%		3M		5
Total/Wtd Avg		$	274			$	171			21		$	14,450			2.99%		1M / 3M		7.8
The following table summarizes our contracts to purchase and sell TBA and specified agency securities on a forward basis as of December 31, 2013 and 2012 (in millions):
		31-Dec-13																December 31, 2012
Purchase and Sale Contracts for TBAs and Forward Settling Securities		Notional				Cost Basis 2				Market Value 3				Net Carrying Value 4				Notional				Cost Basis 2			Market Value 3			Net Carrying Value 4
		Amount 1																Amount 1
TBA securities:
Purchase contracts		$	6,660			$	6,882			$	6,864			$	(18	)		$	21,705			$	22,603		$	22,719		$	116
Sale contracts		(4,541		)		(4,606		)		(4,593		)		13				(9,378		)		(9,991		)	(10,011		)	(20		)
TBA securities, net 5		2,119				2,276				2,271				(5		)		12,327				12,612			12,708			96
Forward settling securities:
Purchase contracts		—				—				—				—				150				163			162			(1		)
Forward settling securities, net 6		—				—				—				—				150				163			162			(1		)
Total TBA and forward settling securities, net		$	2,119			$	2,276			$	2,271			$	(5	)		$	12,477			$	12,775		$	12,870		$	95
________________________
1	Notional amount represents the par value (or principal balance) of the underlying agency security.
2	Cost basis represents the forward price to be paid/(received) for the underlying agency security.
3	Market value represents the current market value of the TBA contract (or of the underlying agency security) as of period-end.
4	Net carrying value represents the difference between the market value and the cost basis of the TBA contract as of period-end and is reported in derivative assets / (liabilities), at fair value in our consolidated balance sheets.
5	Includes 15-year and 30-year TBA securities of varying coupons
6	Includes 30-year fixed securities of varying coupons
Gain (Loss) From Derivative Instruments and Other Securities, Net
The tables below summarize the effect of derivative instruments on our consolidated statements of comprehensive income for fiscal years 2013, 2012 and 2011 related to our derivative and other hedging instruments (in millions):
		Fiscal year 2013
Derivative and Other Hedging Instruments		Notional Amount				Additions			Settlement, Termination,			Notional Amount Long/(Short) December 31, 2013				Amount of
		Long/(Short)							Expiration or							Gain/(Loss)
		31-Dec-12							Exercise							Recognized in
																Income on
																Derivatives 1
Net TBA and forward settling agency securities		$	12,477			42,707			(53,065	)		$	2,119			$	(726	)
Interest rate swaps		$	(46,850	)		(20,750	)		24,350			$	(43,250	)		1,145
Payer swaptions		$	(14,450	)		(23,800	)		24,000			$	(14,250	)		258
U.S. Treasury securities - short position		$	(11,835	)		(31,941	)		41,769			$	(2,007	)		472
U.S. Treasury securities - long position		$	—			27,805			(23,878	)		$	3,927			(42		)
U.S. Treasury futures contracts - short position		$	—			(9,239	)		7,359			$	(1,880	)		49
TBA put option		$	—			(50	)		50			$	—			—
																$	1,156
________________________________
1	Excludes a net gain of $2 million from investments in REIT equity securities, a net gain of $39 million from debt of consolidated VIEs, and other miscellaneous net losses of $6 million recognized in gain (loss) on derivative instruments and other securities, net in our consolidated statements of comprehensive income.
		Fiscal year 2012
Derivative and Other Hedging Instruments		Notional Amount				Additions			Settlement, Termination,			Notional Amount Long/(Short) December 31, 2012				Amount of
		Long/(Short)							Expiration or							Gain/(Loss)
		31-Dec-11							Exercise							Recognized in
																Income on
																Derivatives 1
Net TBA and forward settling agency securities		$	(104	)		(36,174	)		48,755			$	12,477			$	31
Interest rate swaps		$	(30,250	)		(25,000	)		8,400			$	(46,850	)		(1,034		)
Payer swaptions		$	(3,200	)		(18,250	)		7,000			$	(14,450	)		(106		)
U.S. Treasury securities - short position		$	(880	)		(36,555	)		25,600			$	(11,835	)		(142		)
U.S. Treasury securities - long position		$	100			2,445			(2,545	)		$	—			(1		)
U.S. Treasury futures contracts - short position		$	(783	)		(3,838	)		4,621			$	—			(90		)
Markit IOS total return swaps, net		$	(165	)		—			165			$	—			—
																$	(1,342	)
______________________
1	Excludes a net gain of $17 million on interest-only and principal-only securities and a net loss of $28 million from debt of consolidated VIEs recognized in gain (loss) on derivative instruments and other securities, net in our consolidated statements of comprehensive income.
		Fiscal year 2011
Derivative and Other Hedging Instruments 1		Notional Amount				Additions			Additions Due to Hedge De-Designations			Settlement, Termination,			Notional Amount Long/(Short) December 31, 2011				Amount of
		Long/(Short) December 31, 2010										Expiration or							Gain/(Loss)
												Exercise							Recognized in
																			Income on
																			Derivatives 2
Net TBA and forward settling agency securities		$	(849	)		(48,589	)		—			49,334			$	(104	)		$	(142	)
Interest rate swaps		$	(50	)		(6,750	)		(23,900	)		450			$	(30,250	)		(119		)
Payer swaptions		$	(850	)		(5,350	)		—			3,000			$	(3,200	)		(64		)
U.S. Treasury securities - short position		$	(250	)		(15,794	)		—			15,164			$	(880	)		(133		)
U.S. Treasury securities - long position		$	—			5,140			—			(5,040	)		$	100			34
U.S. Treasury futures contracts - short position, net		$	—			(1,083	)		—			300			$	(783	)		(12		)
TBA put option		$	—			(200	)		—			200			$	—			1
Markit IOS total return swaps, net		$	—			510			—			(675	)		$	(165	)		7
																			$	(428	)
________________________________
1	Table excludes activity related to interest rate swaps designated as hedging instruments under ASC 815 prior to our discontinuation of hedge accounting in September 2011.
2	Excludes a net loss of $17 million from interest and principal-only securities and a net loss of $2 million for hedge ineffectiveness recognized in gain (loss) on derivative instruments and other securities, net in our consolidated statements of comprehensive income.
The tables below summarize information about our outstanding interest rate swaps designated as hedging instruments under ASC 815 and their effect on our consolidated statement of comprehensive income for fiscal year 2011, prior to discontinuation of hedge accounting in September 2011 (in millions):
Interest Rate Swaps Designated	Beginning				Additions			Expirations / Terminations			Hedge De-Designations			Ending
as Hedging Instruments	Notional Amount													Notional  Amount
Fiscal year 2011	$	6,450			17,900			(450	)		(23,900	)		$	—
Interest Rate Swaps Designated as Hedging Instruments:		Amount of				Location of Gain		Amount of (Gain) or				Location of Gain or (Loss)		Amount of Gain
		Gain or (Loss)				or (Loss)		Loss Reclassified				Recognized in Earnings		or (Loss)
		Recognized in				Reclassified from		from OCI into				(Ineffective Portion and		Recognized in
		OCI				OCI into		Earnings				Amount Excluded from		Earnings
		(Effective				Earnings (Effective		(Effective Portion)				Effectiveness Testing)		(Ineffective
		Portion)				Portion)								Portion and
														Amount
														Excluded from
														Effectiveness
														Testing)
Fiscal year 2011		$	(707	)		Interest expense		$	(140	)		Gain (loss) on derivative instruments and other securities, net		$	(2	)
Credit Risk-Related Contingent Features
The use of derivatives creates exposure to credit risk relating to potential losses that could be recognized in the event that the counterparties to these instruments fail to perform their obligations under the contracts. We minimize this risk by limiting our counterparties for instruments which are not centrally cleared on a registered exchange to major financial institutions with acceptable credit ratings and monitoring positions with individual counterparties. In addition, we may be required to pledge assets as collateral for our derivatives, whose amounts vary over time based on the market value, notional amount and remaining term of the derivative contract. In the event of a default by a counterparty we may not receive payments provided for under the terms of our derivative agreements, and may have difficulty obtaining our assets pledged as collateral for our derivatives. The cash and cash equivalents and agency securities pledged as collateral for our derivative instruments are included in restricted cash and agency securities, at fair value, respectively, on our consolidated balance sheets.
Each of our International Swaps and Derivatives Association ("ISDA") Master Agreements and central clearing exchange agreements contains provisions under which we are required to fully collateralize our obligations under our interest rate swap agreements if at any point the fair value of the swap represents a liability greater than the minimum transfer amount contained within our agreements. We were also required to post initial collateral upon execution of certain of our swap transactions. If we breach any of these provisions, we will be required to settle our obligations under the agreements at their termination values, which approximates fair value.
Further, each of our ISDA Master Agreements also contains a cross default provision under which a default under certain of our other indebtedness in excess of a certain threshold causes an event of default under the agreement. Threshold amounts vary by lender. Following an event of default, we could be required to settle our obligations under the agreements at their termination values. Additionally, under certain of our ISDA Master Agreements, we could be required to settle our obligations under the agreements at their termination values if we fail to maintain certain minimum stockholders' equity thresholds or our REIT status or if we fail to comply with limits on our leverage above certain specified levels. As of December 31, 2013, the fair value of additional collateral that could be required to be posted as a result of the credit-risk related contingent features being triggered was not material to our consolidated financial statements.
Excluding centrally cleared swaps, as of December 31, 2013, our amount at risk with any counterparty related to our interest rate swap and swaption agreements was less than 2% of our stockholders' equity.
In the case of centrally cleared interest rate swap contracts, we could be exposed to credit risk if the central clearing agency or a clearing member defaults on its respective obligation to perform under the contract. However, we believe that the risk is minimal due to the exchange's initial and daily mark to market margin requirements and a clearinghouse guarantee fund and other resources that are available in the event of a clearing member default.

Offsetting_Assets_and_Liabilit

Offsetting Assets and Liabilities (Notes)	12 Months Ended
	Dec. 31, 2013
Offsetting Assets and Liabilities [Abstract]	'
Offsetting Assets and Liabilities [Text Block]	'
	Offsetting Assets and Liabilities
	Certain of our repurchase agreements and derivative transactions are governed by underlying agreements that generally provide for a right of setoff under master netting arrangements (or similar agreements), including in the event of default or in the event of bankruptcy of either party to the transactions. We present our assets and liabilities subject to such arrangements on a gross basis in our consolidated balance sheets.
	The following tables present information about our assets and liabilities that are subject to such arrangements and can potentially be offset on our consolidated balance sheets as of December 31, 2013 and 2012 (in millions):
			Offsetting of Financial Assets and Derivative Assets
			Gross Amounts of Recognized Assets		Gross Amounts Offset in the Consolidated Balance Sheets		Net Amounts of Assets Presented in the Consolidated Balance Sheets		Gross Amounts Not Offset						Net Amount
									in the
									Consolidated Balance Sheets
									Financial Instruments			Collateral Received 2
	31-Dec-13
	Interest rate swap and swaption agreements, at fair value 1		$	1,138	$	—	$	1,138	$	(331	)	$	(610	)	$	197
	Receivable under reverse repurchase agreements		1,881		—		1,881		(1,881		)	—			—
	Total derivative, other hedging instruments and other assets		$	3,019	$	—	$	3,019	$	(2,212	)	$	(610	)	$	197
	31-Dec-12
	Interest rate swap and swaption agreements, at fair value 1		$	185	$	—	$	185	$	(185	)	$	—		$	—
	Receivable under reverse repurchase agreements		11,818		—		11,818		(10,482		)	(1,157		)	179
	Total derivative, other hedging instruments and other assets		$	12,003	$	—	$	12,003	$	(10,667	)	$	(1,157	)	$	179
			Offsetting of Financial Liabilities and Derivative Liabilities
			Gross Amounts of Recognized Liabilities		Gross Amounts Offset in the Consolidated Balance Sheets		Net Amounts of Liabilities Presented in the Consolidated Balance Sheets		Gross Amounts Not Offset						Net Amount
									in the
									Consolidated Balance Sheets
									Financial Instruments			Collateral Pledged 2
	31-Dec-13
	Interest rate swap agreements, at fair value 1		$	400	$	—	$	400	$	(331	)	$	(69	)	$	—
	Repurchase agreements		63,533		—		63,533		(1,881		)	(61,652		)	—
	Total derivative, other hedging instruments and other liabilities		$	63,933	$	—	$	63,933	$	(2,212	)	$	(61,721	)	$	—
	31-Dec-12
	Interest rate swap agreements, at fair value 1		$	1,243	$	—	$	1,243	$	(185	)	$	(1,058	)	$	—
	Repurchase agreements		74,478		—		74,478		(10,482		)	(63,996		)	—
	Total derivative, other hedging instruments and other liabilities		$	75,721	$	—	$	75,721	$	(10,667	)	$	(65,054	)	$	—
	_______________________
	1	Reported under derivative assets / liabilities, at fair value in the accompanying consolidated balance sheets. Refer to Note 5 for a reconciliation of derivative assets / liabilities, at fair value to their sub-components.
	2	Includes cash and securities received / pledged as collateral, at fair value. Amounts presented are limited to collateral pledged sufficient to reduce the net amount to zero for individual counterparties, as applicable. Refer to Note 3 for additional information regarding assets pledged as collateral.

Fair_Value_Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'
Fair Value Disclosures [Text Block]	'
	We determine the fair value of our agency securities and debt of consolidated VIEs based upon fair value estimates obtained from multiple third party pricing services and dealers.  In determining fair value, third party pricing sources use various valuation approaches, including market and income approaches.  Factors used by third party sources in estimating the fair value of an instrument may include observable inputs such as coupons, primary and secondary mortgage rates, pricing information, credit data, volatility statistics, and other market data that are current as of the measurement date. The availability of observable inputs can vary by instrument and is affected by a wide variety of factors, including the type of instrument, whether the instrument is new and not yet established in the marketplace and other characteristics particular to the instrument.  Third party pricing sources may also use certain unobservable inputs, such as assumptions of future levels of prepayment, defaults and foreclosures, especially when estimating fair values for securities with lower levels of recent trading activity. We make inquiries of third party pricing sources to understand the significant inputs and assumptions they used to determine their prices. For further information regarding valuation of our derivative instruments, please refer to the discussion of derivative and other hedging instruments in Note 2.
	We review the various third party fair value estimates and perform procedures to validate their reasonableness, including an analysis of the range of third party estimates for each position, comparison to recent trade activity for similar securities, and management review for consistency with market conditions observed as of the measurement date. While we do not adjust prices we obtain from third party pricing sources, we will exclude third party prices for securities from our determination of fair value if we determine (based on our validation procedures and our market knowledge and expertise) that the price is significantly different than observable market data would indicate and we cannot obtain an understanding from the third party source as to the significant inputs used to determine the price.
	The validation procedures described above also influence our determination of the appropriate fair value measurement classification.  We utilize a three-level valuation hierarchy for disclosure of fair value measurement. The valuation hierarchy is based upon the transparency of inputs to the valuation of an asset or liability as of the measurement date. A financial instrument's categorization within the hierarchy is based upon the lowest level of input that is significant to the fair value measurement. There were no transfers between hierarchy levels during fiscal years 2013 and 2012. The three levels of hierarchy are defined as follows:
	•	Level 1 Inputs —Quoted prices (unadjusted) for identical unrestricted assets and liabilities in active markets that are accessible at the measurement date.
	•	Level 2 Inputs —Quoted prices for similar assets and liabilities in active markets; quoted prices for identical or similar instruments in markets that are not active; and model-derived valuations whose inputs are observable or whose significant value drivers are observable.
	•	Level 3 Inputs —Instruments with primarily unobservable market data that cannot be corroborated.
	The following table provides a summary of our assets and liabilities that are measured at fair value on a recurring basis as of December 31, 2013 and 2012 (dollars in millions):
		Fair Value Hierarchy
		Level 1		Level 2		Level 3
	December 31, 2013
	Assets:
	Agency securities	$	—	$	65,941	$	—
	U.S. Treasury securities	3,822		—		—
	Interest rate swaps	—		880		—
	Payer swaptions	—		258		—
	REIT equity securities	237		—
	U.S. Treasury futures	39		—		—
	Net TBA and forward settling agency securities	—		17		—
	Total	$	4,098	$	67,096	$	—
	Liabilities:
	Debt of consolidated VIEs	$	—	$	910	$	—
	Obligation to return U.S. Treasury securities borrowed under reverse repurchase agreements	1,848		—		—
	Interest rate swaps	—		400		—
	Net TBA and forward settling agency securities	—		22		—
	Total	$	1,848	$	1,332	$	—
	December 31, 2012
	Assets:
	Agency securities	$	—	$	85,245	$	—
	Interest rate swaps	—		14		—
	Payer swaptions	—		171		—
	Net TBA and forward settling agency securities	—		116		—
	Total	$	—	$	85,546	$	—
	Liabilities:
	Debt of consolidated VIEs	$	—	$	937	$	—
	Obligation to return U.S. Treasury securities borrowed under reverse repurchase agreements	11,763		—		—
	Interest rate swaps	—		1,243		—
	Net TBA and forward settling agency securities	—		21		—
	Total	$	11,763	$	2,201	$	—

Management_Agreement_and_Relat

Management Agreement and Related Party Transactions (Notes)	12 Months Ended
	Dec. 31, 2013
Related Party Transaction [Line Items]	'
Related Party Transactions Disclosure [Text Block]	'
	Management Agreement and Related Party Transactions
	We are externally managed and advised by our Manager pursuant to the terms of a management agreement. The management agreement has been renewed through May 20, 2014 and provides for automatic one-year extension options thereafter. The management agreement may only be terminated by us or our Manager without cause, as defined in the management agreement, after the completion of the current renewal term, or the expiration of each subsequent automatic annual renewal term, provided that either party provide 180-days prior written notice of non-renewal of the management agreement. If we were to not renew the management agreement without cause, we must pay a termination fee on the last day of the applicable term, equal to three times the average annual management fee earned by our Manager during the prior 24-month period immediately preceding the most recently completed month prior to the effective date of termination. We may only not renew the management agreement with or without cause with the consent of the majority of our independent directors. We pay our Manager a base management fee payable monthly in arrears in amount equal to one twelfth of 1.25% of our Equity. Our Equity is defined as our month-end stockholders' equity, adjusted to exclude the effect of any unrealized gains or losses included in either retained earnings or OCI, each as computed in accordance with GAAP.
	There is no incentive compensation payable to our Manager pursuant to the management agreement. For fiscal years 2013, 2012 and 2011, we recorded an expense for management fees of $136 million, $113 million and $55 million, respectively.
	We are obligated to reimburse our Manager for its expenses incurred directly related to our operations, excluding employment-related expenses of our Manager's officers and employees and any American Capital employees who provide services to us pursuant to the management agreement. Our Manager has entered into an administrative services agreement with American Capital, pursuant to which American Capital will provide personnel, services and resources necessary for our Manager to perform its obligations under the management agreement. For fiscal years 2013, 2012 and 2011, we recorded expense reimbursements to our Manager of $10 million, $9 million and $7 million, respectively, consisting mostly of costs related to information technology systems. As of December 31, 2013 and 2012, $13 million and $1 million was payable to our Manager, respectively.

Income_Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2013
Income Tax Examination [Line Items]	'
Income Tax Disclosure [Text Block]	'
	Income Taxes
	The following table summarizes dividends for federal income tax purposes declared for fiscal years 2013, 2012 and 2011 and their related tax characterization (in millions, except per share amounts):
						Tax Characterization
	Fiscal Tax Year	Dividends Declared Per Share		Dividends Declared		Ordinary Income Per Share		Qualified Dividends		Long-Term Capital Gains Per Share
	Series A Cumulative Redeemable Preferred Stock Dividends
	Fiscal year 2013	$	2	$	14	$	2	$	0.01598	$	—
	Fiscal year 2012	$	1.056	$	7	$	0.9523	$	—	$	0.1037
	Common Stock Dividends
	Fiscal year 2013	$	3.75	$	1,453	$	3.75	$	0.029963	$	—
	Fiscal year 2012	$	5	$	1,518	$	4.5092	$	—	$	0.4908
	Fiscal year 2011	$	5.6	$	886	$	5.3324	$	—	$	0.2676
	As of December 31, 2013, we had approximately $210 million of estimated undistributed taxable income that we expect to declare dividends for by the extended due date of our 2013 federal income tax return and pay in 2014. Accordingly, we do not expect to incur any income tax liability on our 2013 taxable income.
	For fiscal years 2013, 2012 and 2011, we did not distribute the required minimum amount of taxable income pursuant to federal excise tax requirements, as described in Note 2, and consequently we accrued an excise tax of $3 million, $25 million and $2 million, respectively, which is included in our net income tax provision on our accompanying consolidated statements of operations and comprehensive income.
	For fiscal years 2013, 2012 and 2011, we recorded an income tax provision of $10 million, an income tax benefit of $6 million and an income tax provision of $4 million, respectively, attributable to our TRS, which is included in our net income tax provision on our accompanying consolidated statements of comprehensive income. The statutory combined federal and state corporate tax rate for our TRS was 39.5% for fiscal years 2013, 2012 and 2011.
	Based on our analysis of any potential uncertain income tax positions, we concluded that we do not have any uncertain tax positions that meet the recognition or measurement criteria of ASC 740 as of December 31, 2013, 2012 and 2011. Our tax returns for tax years 2010 and forward are open to examination by the IRS. In the event that we incur income tax related interest and penalties, our policy is to classify them as a component of provision for income taxes.

Stockholders_Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2013
Stockholders' Equity Note [Abstract]	'
Stockholders' Equity	'
	Stockholders' Equity
	Preferred Stock
	Pursuant to our amended and restated certificate of incorporation, we are authorized to designate and issue up to 10 million shares of preferred stock in one or more classes or series. Our board of directors has designated 6.9 million shares as 8.000% Series A Cumulative Redeemable Preferred Stock ("Series A Preferred Stock"). As of December 31, 2013, we have 3.1 million of authorized but unissued shares of preferred stock. Our board of directors may designate additional series of authorized preferred stock ranking junior to or in parity with the Series A Preferred Stock or designate additional shares of the Series A Preferred Stock and authorize the issuance of such shares.
	In April 2012, we completed a public offering in which 6.9 million shares of our Series A Preferred Stock were sold to the underwriters at a price of $24.21 per share. Upon completion of the offering we received proceeds, net of offering expenses, of approximately $167 million. Our Series A Preferred Stock has no stated maturity and is not subject to any sinking fund or mandatory redemption. Under certain circumstances upon a change of control, the Series A Preferred Stock is convertible to shares of our common stock. Holders of Series A Preferred Stock have no voting rights, except under limited conditions, and holders are entitled to receive cumulative cash dividends at a rate of 8.000% per annum of the $25.00 per share liquidation preference before holders of our common stock are entitled to receive any dividends. Shares of our Series A Preferred Stock are redeemable at $25.00 per share plus accumulated and unpaid dividends (whether or not declared) exclusively at our option commencing on April 5, 2017, or earlier under certain circumstances intended to preserve our qualification as a REIT for Federal income tax purposes. Dividends are payable quarterly in arrears on the 15th day of each January, April, July and October. As of December 31, 2013, we had declared all required quarterly dividends on our Series A Preferred Stock.
	Common Stock Repurchase Program
	In October 2012, our Board of Directors adopted a program that provides for stock repurchases of up to $500 million of our outstanding shares of common stock through December 31, 2013.  In September 2013, our Board of Directors increased the authorized amount to $1 billion of our outstanding shares of common stock and extended its authorization through December 31, 2014. In January 2014, our Board of Directors increased the authorized amount by an additional $1 billion of our outstanding shares of common stock through December 31, 2014. Shares of our common stock may be purchased in the open market, including through block purchases, or through privately negotiated transactions, or pursuant to any trading plan that may be adopted in accordance with Rule 10b5-1 of the Securities Exchange Act of 1934, as amended.  The timing, manner, price and amount of any repurchases will be determined at our discretion and the program may be suspended, terminated or modified at any time for any reason.  We intend to repurchase shares only when the purchase price is less than our estimate of our current net asset value per share of our common stock. Generally, when we repurchase our common stock at a discount to our net asset value, the net asset value of our remaining shares of common stock outstanding increases. In addition, we do not intend to repurchase any shares from directors, officers or other affiliates. The program does not obligate us to acquire any specific number of shares, and all repurchases will be made in accordance with Rule 10b-18, which sets certain restrictions on the method, timing, price and volume of stock repurchases.
	During fiscal year 2013, we repurchased approximately 40.3 million shares of our common stock at an average repurchase price of $21.25 per share, including expenses, totaling $856 million. During fiscal year 2012, we repurchased 2.7 million shares of our common stock at an average repurchase price of $29.00 per share, including expenses, totaling $77 million. As of December 31, 2013, the total remaining amount authorized for repurchases of our common stock was $66 million, excluding the additional amount authorized in January 2014.
	Follow-On Equity Offering
	During fiscal years 2013, 2012 and 2011, we completed follow-on public offerings of shares of our common stock summarized in the table below (in millions, except per share amounts):
	Public Offering		Price Received		Shares		Net Proceeds 2
			Per Share 1
	Fiscal year 2013
	Mar-13		$31.34		57.5		$	1,803
	Total fiscal year 2013				57.5		$	1,803
	Fiscal year 2012
	Mar-12		$29.00		71.2		$	2,063
	Jul-12		$33.70		36.8		1,240
	Total fiscal year 2012				108		$	3,303
	Fiscal year 2011
	Jan-11		$28.00		26.9		$	719
	Mar-11		$27.72		32.2		892
	Jun-11		$27.56		49.7		1,369
	Nov-11		$27.36		40.5		1,108
	Total fiscal year 2011				149.3		$	4,088
	________________________
	1	Price received per share is gross of underwriters' discount, if applicable, and other offering costs.
	2	Net proceeds are net of the underwriters' discount, if applicable, and other offering costs.
	At-the-Market Offering Program
	We have entered into sales agreements with sales agents to publicly offer and sell shares of our common stock in privately negotiated and/or at-the-market transactions from time to time. The table below summarizes sales our common stock under such sales agreements during fiscal years 2012 and 2011 (in millions, except per share amounts):
	At-the-Market Offering		Price Received			Shares			Net Proceeds
			Per Share
	Fiscal year 2012		$	31.41		9.5			$	298
	Fiscal year 2011		$	29.25		9.4			$	273
	During fiscal year 2013, we had no sales under this program. As of December 31, 2013, 16.7 million shares remain available for issuance under this program.
	Dividend Reinvestment and Direct Stock Purchase Plan
	We sponsor a dividend reinvestment and direct stock purchase plan through which stockholders may purchase additional shares of our common stock by reinvesting some or all of the cash dividends received on shares of our common stock. Stockholders may also make optional cash purchases of shares of our common stock subject to certain limitations detailed in the plan prospectus. During fiscal year 2011, we issued 0.5 million shares under the plan for net cash proceeds of $15 million. During fiscal years 2013 and 2012 , there were no shares issued under the plan. As of December 31, 2013, 21.7 million shares remain available for issuance under the plan.
	Accumulated Other Comprehensive Income (Loss)
	The following table summarizes changes to accumulated OCI for fiscal years 2013, 2012 and 2011 (in millions):
	Accumulated Other Comprehensive (Loss) Income		Net Unrealized Gain (Loss) on Available-for-Sale MBS			Net Unrealized Gain (Loss) on Swaps				Total Accumulated OCI
										Balance
	Balance as of December 31, 2010		$	(28	)	$	(40	)		$	(68	)
	OCI before reclassifications		1,512			(844		)		668
	Amounts reclassified from accumulated OCI		(483		)	194				(289		)
	Balance as of December 31, 2011		1,001			(690		)		311
	OCI before reclassifications		2,235			—				2,235
	Amounts reclassified from accumulated OCI		(1,196		)	205				(991		)
	Balance as of December 31, 2012		2,040			(485		)		1,555
	OCI before reclassifications		(4,535		)	—				(4,535		)
	Amounts reclassified from accumulated OCI		1,408			189				1,597
	Balance as of December 31, 2013		$	(1,087	)	$	(296	)		$	(1,383	)
	The following table summarizes reclassifications out of accumulated OCI for fiscal years 2013, 2012 and 2011 (in millions):
			Fiscal Year
	Amounts Reclassified from Accumulated OCI		2013			2012				2011			Line Item in the Consolidated
													Statements of Comprehensive Income
													Where Net Income is Presented
	(Gain) loss amounts reclassified from accumulated OCI for available-for-sale MBS		$	1,408		$	(1,196	)		$	(483	)	Gain (loss) on sale of agency securities, net
	Periodic interest costs of interest rate swaps previously designated as hedges under GAAP, net		189			205				194			Interest expense
	Total reclassifications		$	1,597		$	(991	)		$	(289	)
	Long-term Incentive Plan
	We sponsor an equity incentive plan to provide for the issuance of equity-based awards, including stock options, restricted stock, restricted stock units and unrestricted stock awards to our independent directors. During fiscal years 2013, 2012 and 2011, our independent directors received restricted common stock awards under the plan. The restricted stock awards have a grant date fair value equal to the price of our common stock on such date and vest annually over three years. During fiscal year 2013, we granted 3,000 shares of restricted common stock to each independent director, or a total of 15,000 shares, with a grant date fair value of $31.20 per share. During fiscal year 2012, we granted 3,000 shares of restricted common stock to each independent director, or a total of 12,000 shares, with a weighted average grant date fair value of $29.48 per share. During fiscal year 2011, we granted 3,000 shares of restricted common stock to each independent director, or a total of 12,000 shares, with a grant date fair value of $29.05 per share.
	During fiscal years 2013, 2012 and 2011, an aggregate of 9,500, 7,000 and 4,500 shares of restricted common stock vested under the plan, respectively. The total fair value of restricted stock awards vested during fiscal years 2013, 2012 and 2011 was approximately $290,000, $222,000 and $131,000, respectively, based upon the fair market value of our common stock on the vesting date. During fiscal years 2013, 2012 and 2011, we recognized approximately $383,000, $282,000 and $176,000 of compensation expense under the plan, respectively.
	As of December 31, 2013 and 2012, there was an aggregate 27,000 and 21,500 shares, respectively, of unvested restricted common stock outstanding under the plan and unrecognized compensation costs related to such awards of $481,919 and $397,415, respectively. As of December 31, 2013, 47,500 shares of common stock remained available for future issuance under the plan.

Quarterly_Results

Quarterly Results	12 Months Ended
	Dec. 31, 2013
Quarterly Financial Information [Text Block]	'
	Quarterly Results (Unaudited)
	The following is a presentation of the quarterly results of operations and comprehensive income for fiscal years 2013 and 2012 (in millions, except per share data).
		Quarter Ended
		March 31,			June 30,			September 30,			31-Dec-13
		2013			2013			2013
	Interest income:
	Interest income	$	547		$	545		$	558		$	542
	Interest expense	140			131			145			120
	Net interest income	407			414			413			422
	Other (loss) income:
	(Loss) gain on sale of agency securities, net	(26		)	17			(733		)	(667		)
	(Loss) gain on derivative instruments and other securities, net	(98		)	1,444			(339		)	184
	Total other (loss) income, net	(124		)	1,461			(1,072		)	(483		)
	Expenses:
	Management fees	33			37			35			31
	General and administrative expenses	9			9			7			6
	Total expenses	42			46			42			37
	Income (loss) before income tax	241			1,829			(701		)	(98		)
	Provision for income tax, net	10			—			—			3
	Net income (loss)	231			1,829			(701		)	(101		)
	Dividend on preferred stock	3			3			3			3
	Net income (loss) available (attributable) to common shareholders	$	228		$	1,826		$	(704	)	$	(104	)
	Net income (loss)	$	231		$	1,829		$	(701	)	$	(101	)
	Other comprehensive (loss) income:
	Unrealized (loss) gain on available-for-sale securities, net	(837		)	(2,813		)	833			(311		)
	Unrealized gain on derivative instruments, net	49			48			47			46
	Other comprehensive (loss) income	(788		)	(2,765		)	880			(265		)
	Comprehensive (loss) income	(557		)	(936		)	179			(366		)
	Dividend on preferred stock	3			3			3			3
	Comprehensive (loss) income (attributable) available to common shareholders	$	(560	)	$	(939	)	$	176		$	(369	)
	Weighted average number of common shares outstanding-basic and diluted	356.2			396.4			390.6			373
	Net income (loss) per common share - basic and diluted	$	0.64		$	4.61		$	(1.80	)	$	(0.28	)
	Comprehensive (loss) income per common share - basic and diluted	$	(1.57	)	$	(2.37	)	$	0.45		$	(0.99	)
	Dividends declared per common share	$	1.25		$	1.05		$	0.8		$	0.65
		Quarter Ended
		March 31,			June 30,			September 30,			December 31,
		2012			2012			2012			2012
	Interest income:
	Interest income	$	514		$	504		$	520		$	570
	Interest expense	106			120			139			147
	Net interest income	408			384			381			423
	Other income (loss):
	Gain on sale of agency securities, net	216			417			210			353
	Gain (loss) on derivative instruments and other securities, net	47			(1,029		)	(460		)	89
	Total other income (loss), net	263			(612		)	(250		)	442
	Expenses:
	Management fees	22			28			32			31
	General and administrative expenses	6			8			8			9
	Total expenses	28			36			40			40
	Income (loss) before taxes	643			(264		)	91			825
	Income tax provision (benefit)	2			(3		)	5			15
	Net income (loss)	$	641		$	(261	)	$	86		$	810
	Dividend on preferred stock	—			3			3			3
	Net income (loss) available (attributable) to common shareholders	$	641		$	(264	)	$	83		$	807
	Net income (loss)	$	641		$	(261	)	$	86		$	810
	Other comprehensive (loss) income:
	Unrealized (loss) gain on available-for-sale securities, net	(106		)	689			1,190			(734		)
	Unrealized gain on derivative instruments, net	52			52			51			50
	Other comprehensive (loss) income	(54		)	741			1,241			(684		)
	Comprehensive income	587			480			1,327			126
	Dividend on preferred stock	—			3			3			3
	Comprehensive (loss) income (attributable) available to common shareholders	$	587		$	477		$	1,324		$	123
	Weighted average number of common shares outstanding-basic and diluted	240.6			301			332.8			340.3
Net income (loss) per common share - basic and diluted	$	2.66		$	(0.88	)	$	0.25		$	2.37
Comprehensive income per common share - basic and diluted	$	2.44		$	1.58		$	3.98		$	0.36
Dividends declared per common share	$	1.25		$	1.25		$	1.25		$	1.25

Summary_of_Significant_Account1

Summary of Significant Accounting Policies (Policy)	12 Months Ended
	Dec. 31, 2013
New Accounting Pronouncements or Change in Accounting Principle [Line Items]	'
Basis of Accounting, Policy [Policy Text Block]	'
	Basis of Presentation and Consolidation
	Our consolidated financial statements are prepared in accordance with accounting principles generally accepted in the United States ("GAAP").
	Our consolidated financial statements include the accounts of our wholly-owned subsidiary, American Capital Agency TRS, LLC, and variable interest entities for which we are the primary beneficiary. Significant intercompany accounts and transactions have been eliminated.
Use of Estimates, Policy [Policy Text Block]	'
	Use of Estimates
	The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities at the date of the financial statements and revenues and expenses during the period reported. Actual results could differ from those estimates.
Earnings Per Share, Policy [Policy Text Block]	'
	Earnings per Share
	Basic earnings per share ("EPS") is computed by dividing net income by the weighted average number of common shares outstanding during the period. Diluted EPS assumes the conversion, exercise or issuance of all potential common stock equivalents unless the effect is to reduce a loss or increase the income per share.
Comprehensive Income, Policy [Policy Text Block]	'
	Accumulated Other Comprehensive Income (Loss)
	Accounting Standards Codification ("ASC") Topic 220, Comprehensive Income ("ASC 220"), divides comprehensive income into net income and other comprehensive income (loss) ("OCI"), which includes unrealized gains and losses on securities classified as available-for-sale and unrealized gains and losses on derivative financial instruments that are designated and qualify for cash flow hedge accounting under ASC Topic 815, Derivatives and Hedging ("ASC 815"). During fiscal year 2011, we discontinued designating our derivative financial instruments, principally interest rate swaps, as cash flow hedges. See Derivatives Instruments below and Note 5 for further information regarding our discontinuation of cash flow hedge accounting.
Cash and Cash Equivalents, Policy [Policy Text Block]	'
	Cash and Cash Equivalents
	Cash and cash equivalents consist of unrestricted demand deposits and highly liquid investments with original maturities of three months or less. Cash and cash equivalents are carried at cost, which approximates fair value.
Cash and Cash Equivalents, Restricted Cash and Cash Equivalents, Policy [Policy Text Block]	'
	Restricted Cash
	Restricted cash includes cash pledged as collateral for clearing and executing trades, repurchase agreements, interest rate swaps and other derivative instruments. Restricted cash is carried at cost, which approximates fair value.
Investment Securities	'
	Investment Securities
	ASC Topic 320, Investments—Debt and Equity Securities ("ASC 320"), requires that at the time of purchase, we designate a security as held-to-maturity, available-for-sale or trading, depending on our ability and intent to hold such security to maturity. Securities classified as trading and available-for-sale are reported at fair value, while securities classified as held-to-maturity are reported at amortized cost. We may, from time to time, sell any of our agency securities as part of our overall management of our investment portfolio. Accordingly, we typically designate our agency securities as available-for-sale. All securities classified as available-for-sale are reported at fair value, with unrealized gains and losses reported in accumulated OCI, a separate component of stockholders' equity. Upon the sale of a security, we determine the cost of the security and the amount of unrealized gains or losses to reclassify out of accumulated OCI into earnings based on the specific identification method.
	Interest-only securities and inverse interest-only securities (collectively referred to as "interest-only securities") represent our right to receive a specified proportion of the contractual interest flows of specific agency CMO securities. Principal-only securities represent our right to receive the contractual principal flows of specific agency CMO securities. Interest-only and principal-only securities are measured at fair value through earnings in gain (loss) on derivative instruments and other securities, net in our consolidated statements of comprehensive income. Our investments in interest-only and principal-only securities are included in agency securities, at fair value on the accompanying consolidated balance sheets.
	REIT equity securities represent investments in the common stock of other publicly traded mortgage REITs that invest predominantly in agency MBS. We designate our investments in REIT equity securities as trading securities and report them at fair value on the accompanying consolidated balance sheets.
	We estimate the fair value of our agency securities based on a market approach using "Level 2" inputs from third-party pricing services and non-binding dealer quotes derived from common market pricing methods. Such methods incorporate, but are not limited to, reported trades and executable bid and asked prices for similar securities, benchmark interest rate curves, such as the spread to the U.S. Treasury rate and interest rate swap curves, convexity, duration and the underlying characteristics of the particular security, including coupon, periodic and life caps, rate reset period, issuer, additional credit support and expected life of the security. We estimate the fair value of our REIT equity securities on a market approach using "Level 1" inputs based on quoted market prices. Refer to Note 7 for further discussion of fair value measurements.
	We evaluate our agency securities for other-than-temporary impairment ("OTTI") on at least a quarterly basis. The determination of whether a security is other-than-temporarily impaired may involve judgments and assumptions based on subjective and objective factors. When a security is impaired, an OTTI is considered to have occurred if any one of the following three conditions exist as of the financial reporting date: (i) we intend to sell the security (that is, a decision has been made to sell the security), (ii) it is more likely than not that we will be required to sell the security before recovery of its amortized cost basis or (iii) we do not expect to recover the security's amortized cost basis, even if we do not intend to sell the security and it is not more likely than not that we will be required to sell the security. A general allowance for unidentified impairments in a portfolio of securities is not permitted.
	If either of the first two conditions exists as of the financial reporting date, the entire amount of the impairment loss, if any, is recognized in earnings as a realized loss and the cost basis of the security is adjusted to its fair value. If the third condition exists, the OTTI is separated into (i) the amount relating to credit loss (the "credit component") and (ii) the amount relating to all other factors (the "non-credit components"). Only the credit component is recognized in earnings, with the non-credit components recognized in OCI. However, in evaluating if the third condition exists, our investments in agency securities typically would not have a credit component since the principal and interest are guaranteed by a GSE and, therefore, any unrealized loss is not the result of a credit loss. In addition, since we designate our agency securities as available-for-sale securities with unrealized gains and losses recognized in OCI, any impairment loss for non-credit components is already recognized in OCI.
	The liquidity of the agency securities market allows us to obtain competitive bids and execute on a sale transaction typically within a day of making the decision to sell a security and, therefore, we generally do not make decisions to sell specific agency securities until shortly prior to initiating a sell order. In some instances, we may sell specific agency securities by delivering such securities into existing short to-be-announced ("TBA") contracts. TBA market conventions require the identification of the specific securities to be delivered no later than 48 hours prior to settlement. If we settle a short TBA contract through the delivery of securities, we will generally identify the specific securities to be delivered within one to two days of the 48-hour deadline.
	We did not recognize any OTTI charges on our investment securities for fiscal years 2013, 2012 and 2011
Interest Income	'
	Interest Income
	Interest income is accrued based on the outstanding principal amount of the investment securities and their contractual terms. Premiums or discounts associated with the purchase of investment securities are amortized or accreted into interest income, respectively, over the projected lives of the securities, including contractual payments and estimated prepayments using the interest method in accordance with ASC Subtopic 310-20, Receivables—Nonrefundable Fees and Other Costs ("ASC 310-20").
	We estimate long-term prepayment speeds of our agency securities using a third-party service and market data. The third-party service estimates prepayment speeds using models that incorporate the forward yield curve, current mortgage rates and mortgage rates of the outstanding loans, age and size of the outstanding loans, loan-to-value ratios, volatility and other factors. We review the prepayment speeds estimated by the third-party service and compare the results to market consensus prepayment speeds, if available. We also consider historical prepayment speeds and current market conditions to validate the reasonableness of the prepayment speeds estimated by the third-party service and, based on our Manager's judgment, we may make adjustments to its estimates. Actual and anticipated prepayment experience is reviewed quarterly and effective yields are recalculated when differences arise between (i) our previously estimated future prepayments and (ii) the actual prepayments to date plus our currently estimated future prepayments. If the actual and estimated future prepayment experience differs from our prior estimate of prepayments, we are required to record an adjustment in the current period to the amortization or accretion of premiums and discounts for the cumulative difference in the effective yield through the reporting date.
Repurchase and Resale Agreements Policy [Policy Text Block]	'
	Repurchase Agreements
	We finance the acquisition of securities for our investment portfolio through repurchase transactions under master repurchase agreements. Pursuant to ASC Topic 860, Transfers and Servicing ("ASC 860"), we account for repurchase transactions as collateralized financing transactions, which are carried at their contractual amounts (cost), plus accrued interest, as specified in the respective transactions. Our repurchase agreements have maturities of generally less than one year, but may extend up to five years or more. Interest rates under our repurchase agreements generally correspond to one, three or six month LIBOR plus or minus a fixed spread. The fair value of our repurchase agreements is assumed to equal cost as the interest rates are considered to be at market.
Reverse Repurchase Agreements Policy [Policy Text Block]	'
	Reverse Repurchase Agreements and Obligation to Return Securities Borrowed under Reverse Repurchase Agreements
	We from time to time borrow securities to cover short sales of U.S. Treasury securities through reverse repurchase transactions under our master repurchase agreements (see Derivatives Instruments below). We account for these as securities borrowing transactions and recognize an obligation to return the borrowed securities at fair value on the balance sheet based on the value of the underlying borrowed securities as of the reporting date. Our reverse repurchase agreements generally mature daily. The fair value of our reverse repurchase agreements is assumed to equal cost as the interest rates are reset daily.
Management and Investment Advisory Fees, Policy [Policy Text Block]	'
	Manager Compensation
	Our management agreement provides for the payment to our Manager of a management fee and reimbursement of certain operating expenses, which are accrued and expensed during the period for which they are earned or incurred. Refer to Note 8 for the terms of our management agreement and the administrative services agreement between American Capital and our Manager.
Derivative and other Hedging Instruments	'
	Derivative Instruments
	We use a variety of derivative instruments to hedge a portion of our exposure to market risks, including interest rate risk, prepayment risk and extension risk. The objective of our risk management strategy is to reduce fluctuations in net book value over a range of interest rate scenarios. In particular, we attempt to mitigate the risk of the cost of our variable rate liabilities increasing during a period of rising interest rates. The principal instruments that we use are interest rate swaps and options to enter into interest rate swaps ("interest rate swaptions"). We also utilize forward contracts for the purchase or sale of agency MBS securities on a generic pool, or a TBA contract, basis and on a non-generic, specified pool basis, and we utilize U.S. Treasury securities and U.S. Treasury futures contracts, primarily through short sales. We may also purchase or write put or call options on TBA securities and we may invest in other types of mortgage derivatives, such as interest and principal-only securities, and synthetic total return swaps, such as the Markit IOS Synthetic Total Return Swap Index ("Markit IOS Index").
	We may also enter into TBA contracts as a means of investing in and financing agency securities (thereby increasing our "at risk" leverage) or as a means of disposing of or reducing our exposure to agency securities (thereby reducing our "at risk" leverage). Pursuant to TBA contracts, we agree to purchase or sell, for future delivery, agency securities with certain principal and interest terms and certain types of collateral, but the particular agency securities to be delivered are not identified until shortly before the TBA settlement date. We also may choose, prior to settlement, to move the settlement of these securities out to a later date by entering into an offsetting short or long position (referred to as a "pair off"), net settling the paired off positions for cash, and simultaneously purchasing or selling a similar TBA contract for a later settlement date. This transaction is commonly referred to as a "dollar roll." The agency securities purchased or sold for a forward settlement date are typically priced at a discount to agency securities for settlement in the current month. This difference (or discount) is referred to as the "price drop." The price drop is the economic equivalent of net interest carry income on the underlying agency securities over the roll period (interest income less implied financing cost) and is commonly referred to as "dollar roll income/loss." Consequently, forward purchases of agency securities and dollar roll transactions represent a form of off-balance sheet financing.
	We account for derivative instruments in accordance with ASC Topic 815, Derivatives and Hedging ("ASC 815"). ASC 815 requires an entity to recognize all derivatives as either assets or liabilities in the balance sheet and to measure those instruments at fair value.
	Our derivative agreements generally contain provisions that allow for netting or setting off derivative assets and liabilities with each counterparty; however, we report related assets and liabilities on a gross basis in our consolidated balance sheets. Derivative instruments in a gain position are reported as derivative assets at fair value and derivative instruments in a loss position are reported as derivative liabilities at fair value in our consolidated balance sheets. Changes in fair value of derivative instruments and periodic settlements related to our derivative instruments are recorded in gain (loss) on derivative instruments and other securities, net in our consolidated statements of comprehensive income. Cash receipts and payments related to derivative instruments are classified in our consolidated statements of cash flows according to the underlying nature or purpose of the derivative transaction, generally in the investing section.
	The use of derivatives creates exposure to credit risk relating to potential losses that could be recognized in the event that the counterparties to these instruments fail to perform their obligations under the contracts. We attempt to minimize this risk by limiting our counterparties to major financial institutions with acceptable credit ratings, monitoring positions with individual counterparties and adjusting posted collateral as required.
	Discontinuation of hedge accounting for interest rate swap agreements
	Prior to September 30, 2011, we entered into interest rate swap agreements typically with the intention of qualifying for hedge accounting under ASC 815. However, as of September 30, 2011, we elected to discontinue hedge accounting for our interest rate swaps. Upon discontinuation of hedge accounting, the net deferred loss related to our de-designated interest rate swaps remained in accumulated OCI and is being reclassified from accumulated OCI into interest expense on a straight-line basis over the remaining term of each interest rate swap.
	Interest rate swap agreements
	We use interest rate swaps to hedge the variable cash flows associated with borrowings made under our repurchase agreement facilities. Under our interest rate swap agreements, we typically pay a fixed rate and receive a floating rate based on one, three or six-month LIBOR ("payer swaps") with terms up to 20 years. The floating rate we receive under our swap agreements has the effect of offsetting the repricing characteristics of our repurchase agreements and cash flows on such liabilities. Our swap agreements are privately negotiated in the over−the−counter ("OTC") market and may be centrally cleared through a registered commodities exchange ("centrally cleared swaps").
	We estimate the fair value of our centrally cleared interest rate swaps using the daily settlement price determined by the respective exchange. Centrally cleared swaps are valued by the exchange using a pricing model that references the underlying rates including the overnight index swap rate and LIBOR forward rate to produce the daily settlement price.
	We estimate the fair value of our "non-centrally cleared" swaps using a combination of inputs from counterparty and third-party pricing models to estimate the net present value of the future cash flows using a forward interest rate yield curve in effect as of the end of the measurement period. We also incorporate both our own and our counterparties' nonperformance risk in estimating the fair value of our interest rate swaps. In considering the effect of nonperformance risk, we consider the impact of netting and credit enhancements, such as collateral postings and guarantees, and have concluded that our own and our counterparty risk is not significant to the overall valuation of these agreements.
	Interest rate swaptions
	We purchase interest rate swaptions to help mitigate the potential impact of larger increases or decreases in interest rates on the performance of our investment portfolio (referred to as "convexity risk"). The interest rate swaptions provide us the option to enter into an interest rate swap agreement for a predetermined notional amount, stated term and pay and receive interest rates in the future. Our swaption agreements typically provide us the option to enter into a pay fixed rate interest rate swap, which we refer as "payer swaptions." We may also enter into swaption agreements that provide us the option to enter into a receive fixed interest rate swap, which we refer to as "receiver swaptions." The premium paid for interest rate swaptions is reported as an asset in our consolidated balance sheets. The premium is valued at an amount equal to the fair value of the swaption that would have the effect of closing the position adjusted for nonperformance risk, if any. The difference between the premium and the fair value of the swaption is reported in gain (loss) on derivative instruments and other securities, net in our consolidated statements of comprehensive income. If a swaption expires unexercised, the realized loss on the swaption would be equal to the premium paid. If we sell or exercise a swaption, the realized gain or loss on the swaption would be equal to the difference between the cash or the fair value of the underlying interest rate swap received and the premium paid.
	Our interest rates swaption agreements are privately negotiated in the OTC market and are not subject to central clearing. We estimate the fair value of interest rate swaptions using a combination of inputs from counterparty and third-party pricing models based on the fair value of the future interest rate swap that we have the option to enter into as well as the remaining length of time that we have to exercise the option, adjusted for non-performance risk, if any.
	TBA securities
	A TBA security is a forward contract for the purchase ("long position") or sale ("short position") of agency MBS at a predetermined price, face amount, issuer, coupon and stated maturity on an agreed-upon future date. The specific agency MBS delivered into the contract upon the settlement date, published each month by the Securities Industry and Financial Markets Association, are not known at the time of the transaction. We may enter into TBA contracts as a means of hedging against short-term changes in interest rates. We may also enter into TBA contracts as a means of acquiring or disposing of agency securities and we may from time to time utilize TBA dollar roll transactions to finance agency MBS purchases.
	We account for TBA contracts as derivative instruments since we cannot assert that it is probable at inception and throughout the term of the TBA contract that we will take physical delivery of the agency security upon settlement of the contract. We account for TBA dollar roll transactions as a series of derivative transactions. Gains, losses and dollar roll income associated with our TBA contracts and dollar roll transactions are recognized in our consolidated statements of comprehensive income in gain (loss) on derivative instruments and other securities, net.
	We estimate the fair value of TBA securities based on similar methods used to value our agency MBS securities.
	Forward commitments to purchase or sell specified agency MBS
	We enter into forward commitments to purchase or sell specified agency MBS from time to time as a means of acquiring assets or as a hedge against short-term changes in interest rates. Such forward commitments typically require physical settlement. We account for such forward commitments as derivatives if the delivery of the specified agency MBS and settlement extend beyond established market conventions. Realized and unrealized gains and losses associated with forward commitments accounted for as derivatives are recognized in our consolidated statements of comprehensive income in gain (loss) on derivative instruments and other securities, net.
	We estimate the fair value of forward commitments to purchase or sell specified agency MBS based on similar methods used to value agency MBS, as well as the remaining length of time of the forward commitment.
	U.S. Treasury securities
	We purchase or sell short U.S. Treasury securities and U.S. Treasury futures contracts to help mitigate the potential impact of changes in interest rates on the performance of our portfolio. Gains and losses associated with purchases and short sales of U.S. Treasury securities and U.S. Treasury futures contracts are recognized in gain (loss) on derivative instruments and other securities, net in our consolidated statements of comprehensive income.
Consolidation, Variable Interest Entity, Policy [Policy Text Block]	'
	Variable Interest Entities
	ASC Topic 810, Consolidation ("ASC 810"), requires an enterprise to consolidate a variable interest entity ("VIE") if it is deemed the primary beneficiary of the VIE. Further, ASC 810 requires a qualitative assessment to determine the primary beneficiary of a VIE and ongoing assessments of whether an enterprise is the primary beneficiary of a VIE as well as additional disclosures for entities that have variable interests in VIEs.
	We have entered into transactions involving CMO trusts, which are VIEs. We will consolidate a CMO trust if we are the CMO trust's primary beneficiary; that is, if we have a variable interest that provides us with a controlling financial interest in the CMO trust. An entity is deemed to have a controlling financial interest if the entity has the power to direct the activities of a VIE that most significantly impact the VIE's economic performance and the obligation to absorb losses of or right to receive benefits from the VIE that could potentially be significant to the VIE. As part of the qualitative assessment in determining if we have a controlling financial interest, we evaluate whether we control the selection of financial assets transferred to the CMO trust. For each of our consolidated CMO trusts we controlled the selection of the agency MBS transferred from our investment portfolio to an investment bank in exchange for cash proceeds and at the same time entered into a commitment with the investment bank to purchase to-be-issued securities collateralized by the agency MBS transferred, which resulted in our consolidation of the CMO trusts.
	Agency MBS transferred to consolidated VIEs are reported on our consolidated balance sheets in agency securities transferred to consolidated VIEs, at fair value and can only be used to settle the obligations of each respective VIE.
	We report debt issued in connection with the CMO trusts on our consolidated balance sheets in debt of consolidated VIEs, at fair value, which represents tranches within the trusts sold to third-parties and excludes tranches acquired by us that eliminate upon consolidation. The third-party beneficial interest holders in the VIEs have no recourse against our general credit. We elected the option to account for the consolidated debt at fair value, with changes in fair value reflected in earnings during the period in which they occur, because we believe this election more appropriately reflects our financial position as both the consolidated assets and consolidated debt are presented in a consistent manner on our consolidated balance sheets. We estimate the fair value of the consolidated debt based on a market approach using "Level 2" inputs from third-party pricing services and dealer quotes.
Income Tax, Policy [Policy Text Block]	'
	Income Taxes
	We elected to be taxed as a REIT under the provisions of the Internal Revenue Code and the corresponding provisions of state law, commencing with our initial tax year ended December 31, 2008. In order to qualify as a REIT, we must annually distribute, in a timely manner to our stockholders, at least 90% of our taxable ordinary income. A REIT is not subject to tax on its earnings to the extent that it distributes its annual taxable income to its stockholders and as long as certain asset, income and stock ownership tests are met. We operate in a manner that will allow us to be taxed as a REIT. As permitted by the Internal Revenue Code, a REIT can designate dividends paid in the subsequent year as dividends of the current year if those dividends are both declared by the extended due date of the REIT's federal income tax return and paid to stockholders by the last day of the subsequent year.
	As a REIT, if we fail to distribute in any calendar year at least the sum of (i) 85% of our ordinary income for such year, (ii) 95% of our capital gain net income for such year and (iii) any undistributed taxable income from the prior year, we are subject to a non-deductible 4% excise tax on the excess of such required distribution over the sum of (a) the amounts actually distributed and, if applicable, (b) the amounts of income we retained and on which we have paid corporate income tax. Dividends declared by December 31 and paid by January 31 are treated as having been a distribution of our taxable income for the prior tax year.
	We and our domestic subsidiary, American Capital Agency TRS, LLC, have made a joint election to treat our subsidiary as a taxable REIT subsidiary. As such, American Capital Agency TRS, LLC, is subject to federal and state income tax.
	We evaluate uncertain income tax positions, if any, in accordance with ASC Topic 740, Income Taxes ("ASC 740"). To the extent we incur interest and/or penalties in connection with our tax obligations, such amounts shall be classified as income tax expense on our consolidated statements of operations.
Reclassification, Policy [Policy Text Block]	'
	Reclassifications
	Certain prior period amounts in the consolidated financial statements have been reclassified to conform to the current period presentation.
Discontinuation of Election to Account for Interest Rate Swaps as Designated Cash Flow Hedges [Member]	'
New Accounting Pronouncements or Change in Accounting Principle [Line Items]	'
Derivative and other Hedging Instruments	'
	Discontinuation of hedge accounting for interest rate swap agreements
	Prior to September 30, 2011, we entered into interest rate swap agreements typically with the intention of qualifying for hedge accounting under ASC 815. However, as of September 30, 2011, we elected to discontinue hedge accounting for our interest rate swaps. Upon discontinuation of hedge accounting, the net deferred loss related to our de-designated interest rate swaps remained in accumulated OCI and is being reclassified from accumulated OCI into interest expense on a straight-line basis over the remaining term of each interest rate swap.

Investment_Securities_Tables

Investment Securities (Tables)	12 Months Ended
	Dec. 31, 2013
Available-for-sale Securities [Abstract]	'
Agency Securities [Table Text Block]	'
	The following tables summarize our investments in agency MBS as of December 31, 2013 (dollars in millions):
			31-Dec-13
	Agency MBS		Fannie Mae			Freddie Mac				Ginnie Mae				Total
	Available-for-sale agency MBS:
	Agency MBS, par		$	50,914		$	12,640			$	223			$	63,777
	Unamortized discount		(25		)	(7		)		—				(32		)
	Unamortized premium		2,210			631				7				2,848
	Amortized cost		53,099			13,264				230				66,593
	Gross unrealized gains		181			74				5				260
	Gross unrealized losses		(991		)	(358		)		—				(1,349		)
	Total available-for-sale agency MBS, at fair value		52,289			12,980				235				65,504
	Agency MBS remeasured at fair value through earnings:
	Interest-only and principal-only strips, amortized cost 1		400			32				—				432
	Gross unrealized gains		13			3				—				16
	Gross unrealized losses		(9		)	(2		)		—				(11		)
	Total agency MBS remeasured at fair value through earnings		404			33				—				437
	Total agency MBS, at fair value		$	52,693		$	13,013			$	235			$	65,941
	Weighted average coupon as of December 31, 2013 2		3.53		%	3.78		%		3.56		%		3.58		%
	Weighted average yield as of December 31, 2013 3		2.66		%	2.87		%		1.66		%		2.7		%
	Weighted average yield for the year ended December 31, 2013 3		2.74		%	2.87		%		1.79		%		2.77		%
	________________________
	1	The underlying unamortized principal balance ("UPB" or "par value") of our interest-only agency MBS strips was $1.4 billion and the weighted average contractual interest we are entitled to receive was 5.50% of this amount as of December 31, 2013. The par value of our principal-only agency MBS strips was $271 million as of December 31, 2013.
	2	The weighted average coupon includes the interest cash flows from our interest-only agency MBS strips taken together with the interest cash flows from our fixed-rate, adjustable-rate and CMO agency MBS as a percentage of the par value of our agency MBS (excluding the UPB of our interest-only securities) as of December 31, 2013.
	3	Incorporates a weighted average future constant prepayment rate assumption of 7% based on forward rates as of December 31, 2013
	The following tables summarize our investments in agency MBS as of December 31, 2012 (dollars in millions):
			December 31, 2012
	Agency MBS		Fannie Mae			Freddie Mac				Ginnie Mae				Total
	Available-for-sale agency MBS:
	Agency MBS, par		$	58,912		$	19,336			$	238			$	78,486
	Unamortized premium		3,208			948				10				4,166
	Amortized cost		62,120			20,284				248				82,652
	Gross unrealized gains		1,585			481				6				2,072
	Gross unrealized losses		(18		)	(7		)		—				(25		)
	Total available-for-sale agency MBS, at fair value		63,687			20,758				254				84,699
	Agency MBS remeasured at fair value through earnings:
	Interest-only and principal-only strips, amortized cost 1		486			55				—				541
	Gross unrealized gains		26			1				—				27
	Gross unrealized losses		(9		)	(13		)		—				(22		)
	Total agency MBS remeasured at fair value through earnings		503			43				—				546
	Total agency MBS, at fair value		$	64,190		$	20,801			$	254			$	85,245
	Weighted average coupon as of December 31, 2012 2		3.7		%	3.67		%		3.77		%		3.69		%
	Weighted average yield as of December 31, 2012 3		2.62		%	2.61		%		1.6		%		2.61		%
	Weighted average yield for the year ended December 31, 2012 3		2.83		%	2.83		%		1.63		%		2.82		%
	________________________
	1	The UPB of our interest-only securities was $1.7 billion and the weighted average contractual interest we are entitled to receive was 5.78% of this amount as of December 31, 2012. The par value of our principal-only agency MBS strips was $302 million as of December 31, 2012.
	2	The weighted average coupon includes the interest cash flows from our interest-only securities taken together with the interest cash flows from our fixed-rate, adjustable-rate and CMO securities as a percentage of the par value of our agency securities (excluding the UPB of our interest-only securities) as of December 31, 2012.
	3	Incorporates a weighted average future constant prepayment rate assumption of 11% based on forward rates as of December 31, 2012.
			December 31, 2012
	Agency MBS		Amortized			Gross				Gross				Fair Value
			Cost			Unrealized				Unrealized
						Gain				Loss
	Fixed-Rate		$	81,617		$	2,043			$	(25	)		$	83,635
	Adjustable-Rate		865			26				—				891
	CMO		170			3				—				173
	Interest-only and principal-only strips		541			27				(22		)		546
	Total agency MBS		$	83,193		$	2,099			$	(47	)		$	85,245
Components of Investment Securities [Table Text Block]	'
			31-Dec-13
	Agency MBS		Amortized			Gross				Gross				Fair Value
			Cost			Unrealized				Unrealized
						Gain				Loss
	Fixed-Rate		$	64,057		$	242			$	(1,338	)		$	62,961
	Adjustable-Rate		1,223			15				(3		)		1,235
	CMO		1,313			3				(8		)		1,308
	Interest-only and principal-only strips		432			16				(11		)		437
	Total agency MBS		$	67,025		$	276			$	(1,360	)		$	65,941
			December 31, 2012
	Agency MBS		Amortized			Gross				Gross				Fair Value
			Cost			Unrealized				Unrealized
						Gain				Loss
	Fixed-Rate		$	81,617		$	2,043			$	(25	)		$	83,635
	Adjustable-Rate		865			26				—				891
	CMO		170			3				—				173
	Interest-only and principal-only strips		541			27				(22		)		546
	Total agency MBS		$	83,193		$	2,099			$	(47	)		$	85,245
			December 31, 2012
	Agency MBS		Amortized			Gross				Gross				Fair Value
			Cost			Unrealized				Unrealized
						Gain				Loss
	Fixed-Rate		$	81,617		$	2,043			$	(25	)		$	83,635
	Adjustable-Rate		865			26				—				891
	CMO		170			3				—				173
	Interest-only and principal-only strips		541			27				(22		)		546
	Total agency MBS		$	83,193		$	2,099			$	(47	)		$	85,245
Summary Of Agency Securities Estimated Weighted Average Life Classifications	'
	The following table summarizes our agency MBS classified as available-for-sale as of December 31, 2013 and 2012 according to their estimated weighted average life classification (dollars in millions):
			31-Dec-13											December 31, 2012
	Estimated Weighted Average Life of Agency MBS Classified as Available-for-Sale 1		Fair Value			Amortized				Weighted		Weighted		Fair Value			Amortized		Weighted		Weighted
						Cost				Average		Average					Cost		Average		Average
										Coupon		Yield							Coupon		Yield
	≤ 1 year		$	129		$	129			3.07%		2.53%		$	—		$	—	—%		—%
	> 1 year and ≤ 3 years		498			491				4.08%		2.25%		1,119			1,108		4.18%		2.14%
	> 3 years and ≤ 5 years		24,471			24,342				3.59%		2.57%		27,448			26,750		3.36%		2.29%
	> 5 years and ≤10 years		38,522			39,635				3.39%		2.73%		54,054			52,735		3.69%		2.75%
	> 10 years		1,884			1,996				3.66%		2.96%		2,078			2,059		3.44%		2.65%
	Total		$	65,504		$	66,593			3.47%		2.68%		$	84,699		$	82,652	3.59%		2.59%
	_______________________
	1	Excludes interest and principal-only strips.
Summary of Changes in Accumulated OCI for Agency Securitie [Table Text Block]	'
	The following table summarizes changes in accumulated OCI, a separate component of stockholders' equity, for our available-for-sale securities for fiscal years 2013, 2012 and 2011 (in millions):
	Agency Securities Classified as		Beginning Accumulated OCI			Unrealized			Reversal of			Ending
	Available-for-Sale		Balance			Gains and (Losses), Net			Unrealized			Accumulated OCI
									(Gains) and Losses,			Balance
									Net on Realization
	Fiscal year 2013		$	2,040		(4,535	)		1,408			$	(1,087	)
	Fiscal year 2012		$	1,001		2,235			(1,196	)		$	2,040
	Fiscal year 2011		$	(28	)	1,512			(483	)		$	1,001
Summary of Continuous Unrealized Loss Position of Available for Sale Securities [Table Text Block]	'
	The following table presents the gross unrealized loss and fair values of our available-for-sale agency securities by length of time that such securities have been in a continuous unrealized loss position as of December 31, 2013 and 2012 (in millions):
			Unrealized Loss Position For
			Less than 12 Months							12 Months or More							Total
	Agency Securities Classified as		Estimated Fair			Unrealized				Estimated				Unrealized			Estimated Fair		Unrealized
	Available-for-Sale		Value			Loss				Fair Value				Loss			Value		Loss
	December 31, 2013		$	42,853		$	(1,248	)		$	1,586			$	(101	)	$	44,439	$	(1,349	)
	December 31, 2012		$	8,430		$	(25	)		$	—			$	—		$	8,430	$	(25	)
Summary of Net Gain from Sale of Agency Securities [Table Text Block]	'
	The following table is a summary of our net gain (loss) from the sale of agency securities classified as available-for-sale for fiscal years 2013, 2012 and 2011 (in millions):
			Fiscal Year
	Agency Securities Classified as		2013			2012				2011
	Available-for-Sale
	Agency MBS sold, at cost		$	(81,516	)	$	(63,610	)		$	(37,579	)
	Proceeds from agency MBS sold 1		80,108			64,806				38,052
	Net (loss) gain on sale of agency MBS		$	(1,408	)	$	1,196			$	473
	Gross gain on sale of agency MBS		$	217		$	1,209			$	510
	Gross loss on sale of agency MBS		(1,625		)	(13		)		(37		)
	Net (loss) gain on sale of agency MBS		$	(1,408	)	$	1,196			$	473
	________________________
	1	Proceeds include cash received during the period, plus receivable for agency MBS sold during the period as of period end.
Schedule of Investments Owned and Pledged as Collateral [Table Text Block]	'
	The following tables summarize our assets pledged as collateral under repurchase agreements, debt of consolidated VIEs, derivative agreements and prime broker agreements by type, including securities pledged related to securities sold but not yet settled, as of December 31, 2013 and 2012 (in millions):
			December 31, 2013
	Assets Pledged		Repurchase Agreements			Debt of Consolidated VIEs				Derivative Agreements				Prime Broker Agreements			Total
	Agency MBS - fair value		$	62,708		$	1,459			$	28			$	91		$	64,286
	U.S. Treasury securities - fair value		3,708			—				70				—			3,778
	Accrued interest on pledged securities		189			5				1				—			195
	Restricted cash		3			—				41				57			101
	Total		$	66,608		$	1,464			$	140			$	148		$	68,360
			December 31, 2012
	Assets Pledged		Repurchase Agreements			Debt of Consolidated VIEs				Derivative Agreements				Prime Broker Agreements			Total
	Agency MBS - fair value		$	78,400		$	1,535			$	1,065			$	501		$	81,501
	Accrued interest on pledged securities		217			5				3				1			226
	Restricted cash		—			—				249				150			399
	Total		$	78,617		$	1,540			$	1,317			$	652		$	82,126
Summary Of Agency Securities Pledged As Collateral Under Repurchase Agreements by Remaining Maturity	'
	The following table summarizes our securities pledged as collateral under repurchase agreements and debt of consolidated VIEs by remaining maturity, including securities pledged related to sold but not yet settled securities, as of December 31, 2013 and 2012 (in millions):
			December 31, 2013											December 31, 2012
	Agency Securities Pledged by Remaining Maturity of Repurchase Agreements and Debt of Consolidated VIEs		Fair Value of Pledged Securities			Amortized				Accrued				Fair Value of Pledged Securities			Amortized		Accrued
						Cost of Pledged Securities				Interest on							Cost of Pledged Securities		Interest on
										Pledged									Pledged
										Securities									Securities
	Agency MBS:
	≤ 30 days		$	27,694		$	28,125			$	76			$	29,284		$	28,525	$	82
	> 30 and ≤ 60 days		14,955			15,210				42				21,716			21,251		58
	> 60 and ≤ 90 days		10,117			10,290				28				16,188			15,780		45
	> 90 days		11,401			11,623				32				12,747			12,447		37
	Total agency MBS		64,167			65,248				178				79,935			78,003		222
	U.S. Treasury securities:
	1 day		3,708			3,760				16				—			—		—
	Total		$	67,875		$	69,008			$	194			$	79,935		$	78,003	$	222

Recovered_Sheet1

Repurchase Agreements and Other Debt (Tables)	12 Months Ended
	Dec. 31, 2013
Disclosure of Repurchase Agreements [Abstract]	'
Schedule of Borrowings under Repurchase Agreements and Weighted Average Interest Rates [Table Text Block]	'
	The following table summarizes our borrowings under repurchase arrangements and weighted average interest rates classified by remaining maturities as of December 31, 2013 and 2012 (dollars in millions):
		31-Dec-13					December 31, 2012
	Remaining Maturity	Repurchase Agreements		Weighted		Weighted	Repurchase Agreements		Weighted		Weighted
				Average		Average Days			Average		Average Days
				Interest		to Maturity			Interest		to Maturity
				Rate					Rate
	Agency MBS:
	≤ 1 month	$	23,577	0.42	%	15	$	25,474	0.48	%	17
	> 1 to ≤ 3 months	20,490		0.43	%	61	30,402		0.49	%	57
	> 3 to ≤ 6 months	6,946		0.45	%	140	7,208		0.53	%	128
	> 6 to ≤ 9 months	2,232		0.53	%	230	4,509		0.57	%	234
	> 9 to ≤ 12 months	3,607		0.54	%	323	2,149		0.6	%	312
	> 12 to ≤ 24 months	3,261		0.6	%	603	2,142		0.65	%	591
	> 24 to ≤ 36 months	500		0.62	%	930	2,492		0.69	%	1,002
	> 36 months	602		0.68	%	1,468	102		0.73	%	1,751
	Total agency MBS	61,215		0.45	%	124	74,478		0.51	%	118
	U.S. Treasury securities:
	1 day	2,318		0.02	%	1	—		—	%	—
	Total / Weighted Average	$	63,533	0.44	%	119	$	74,478	0.51	%	118

Derivative_and_Other_Hedging_I1

Derivative and Other Hedging Instruments (Tables)	12 Months Ended
	Dec. 31, 2013
Derivative [Line Items]	'
Derivative Instruments, Gain (Loss) [Table Text Block]	'
	The tables below summarize information about our outstanding interest rate swaps designated as hedging instruments under ASC 815 and their effect on our consolidated statement of comprehensive income for fiscal year 2011, prior to discontinuation of hedge accounting in September 2011 (in millions):
	Interest Rate Swaps Designated	Beginning				Additions			Expirations / Terminations			Hedge De-Designations			Ending
	as Hedging Instruments	Notional Amount													Notional  Amount
	Fiscal year 2011	$	6,450			17,900			(450	)		(23,900	)		$	—
	Interest Rate Swaps Designated as Hedging Instruments:		Amount of				Location of Gain		Amount of (Gain) or				Location of Gain or (Loss)		Amount of Gain
			Gain or (Loss)				or (Loss)		Loss Reclassified				Recognized in Earnings		or (Loss)
			Recognized in				Reclassified from		from OCI into				(Ineffective Portion and		Recognized in
			OCI				OCI into		Earnings				Amount Excluded from		Earnings
			(Effective				Earnings (Effective		(Effective Portion)				Effectiveness Testing)		(Ineffective
			Portion)				Portion)								Portion and
															Amount
															Excluded from
															Effectiveness
															Testing)
	Fiscal year 2011		$	(707	)		Interest expense		$	(140	)		Gain (loss) on derivative instruments and other securities, net		$	(2	)
Schedule of Outstanding Derivatives Not Designated as Hedging Instruments [Table Text Block]	'
	The table below summarizes fair value information about our derivative assets and liabilities as of December 31, 2013 and 2012 (in millions):
	Derivatives Instruments		Balance Sheet Location		December 31, 2013				December 31, 2012
	Interest rate swaps		Derivative assets, at fair value		$	880			$	14
	Payer swaptions		Derivative assets, at fair value		258				171
	Purchase of TBA and forward settling agency securities		Derivative assets, at fair value		2				116
	Sale of TBA and forward settling agency securities		Derivative assets, at fair value		15				—
	U.S. Treasury futures - short		Derivative assets, at fair value		39				—
					$	1,194			$	301
	Interest rate swaps		Derivative liabilities, at fair value		$	(400	)		$	(1,243	)
	Purchase of TBA and forward settling agency securities		Derivative liabilities, at fair value		(20		)		(1		)
	Sale of TBA and forward settling agency securities		Derivative liabilities, at fair value		(2		)		(20		)
					$	(422	)		$	(1,264	)
Schedule of Interest Rate Swaption Agreements Outstandin [Table Text Block]	'
	The following tables summarize our interest rate swaption agreements outstanding as of December 31, 2013 and 2012 (dollars in millions):
			December 31, 2013
			Option										Underlying Swap
	Payer Swaptions		Cost				Fair				Average		Notional				Average Fixed Pay		Average		Average
							Value				Months to		Amount				Rate		Receive		Term
											Expiration								Rate		(Years)
																			(LIBOR)
	≤ 1 year		$	193			$	117			4		$	9,400			2.87%		3M		7.8
	> 1 to ≤ 2 years		105				92				19		3,600				3.40%		3M		5.6
	> 2 to ≤ 3 years		35				45				30		1,150				3.81%		3M		5.8
	> 3 to ≤ 5 years		2				4				52		100				4.80%		3M		7
	Total/Wtd Avg		$	335			$258				10		$	14,250			3.09%		3M		7
			December 31, 2012
			Option										Underlying Swap
	Payer Swaptions		Cost				Fair				Average		Notional				Average Fixed Pay		Average		Average
							Value				Months to		Amount				Rate		Receive		Term
											Expiration								Rate		(Years)
																			(LIBOR)
	≤ 1 year		$	76			$	15			4		$	5,150			2.65%		1M / 3M		8.6
	> 1 to ≤ 2 years		65				34				19		4,050				2.82%		3M		6.7
	> 2 to ≤ 3 years		97				87				33		3,900				3.51%		3M		8.6
	> 3 to ≤ 4 years		12				11				46		450				3.20%		3M		6.1
	> 4 to ≤ 5 years		24				24				59		900				3.33%		3M		5
	Total/Wtd Avg		$	274			$	171			21		$	14,450			2.99%		1M / 3M		7.8
Summary of Long and Short Position of Derivative Instruments	'
	The following table summarizes our contracts to purchase and sell TBA and specified agency securities on a forward basis as of December 31, 2013 and 2012 (in millions):
			31-Dec-13																December 31, 2012
	Purchase and Sale Contracts for TBAs and Forward Settling Securities		Notional				Cost Basis 2				Market Value 3				Net Carrying Value 4				Notional				Cost Basis 2			Market Value 3			Net Carrying Value 4
			Amount 1																Amount 1
	TBA securities:
	Purchase contracts		$	6,660			$	6,882			$	6,864			$	(18	)		$	21,705			$	22,603		$	22,719		$	116
	Sale contracts		(4,541		)		(4,606		)		(4,593		)		13				(9,378		)		(9,991		)	(10,011		)	(20		)
	TBA securities, net 5		2,119				2,276				2,271				(5		)		12,327				12,612			12,708			96
	Forward settling securities:
	Purchase contracts		—				—				—				—				150				163			162			(1		)
	Forward settling securities, net 6		—				—				—				—				150				163			162			(1		)
	Total TBA and forward settling securities, net		$	2,119			$	2,276			$	2,271			$	(5	)		$	12,477			$	12,775		$	12,870		$	95
	________________________
	1	Notional amount represents the par value (or principal balance) of the underlying agency security.
	2	Cost basis represents the forward price to be paid/(received) for the underlying agency security.
	3	Market value represents the current market value of the TBA contract (or of the underlying agency security) as of period-end.
	4	Net carrying value represents the difference between the market value and the cost basis of the TBA contract as of period-end and is reported in derivative assets / (liabilities), at fair value in our consolidated balance sheets.
	5	Includes 15-year and 30-year TBA securities of varying coupons
	6	Includes 30-year fixed securities of varying coupons
Schedule Of Outstanding Not Designated As Hedging Instruments [Table Text Block]	'
			Fiscal year 2012
	Derivative and Other Hedging Instruments		Notional Amount				Additions			Settlement, Termination,			Notional Amount Long/(Short) December 31, 2012				Amount of
			Long/(Short)							Expiration or							Gain/(Loss)
			31-Dec-11							Exercise							Recognized in
																	Income on
																	Derivatives 1
	Net TBA and forward settling agency securities		$	(104	)		(36,174	)		48,755			$	12,477			$	31
	Interest rate swaps		$	(30,250	)		(25,000	)		8,400			$	(46,850	)		(1,034		)
	Payer swaptions		$	(3,200	)		(18,250	)		7,000			$	(14,450	)		(106		)
	U.S. Treasury securities - short position		$	(880	)		(36,555	)		25,600			$	(11,835	)		(142		)
	U.S. Treasury securities - long position		$	100			2,445			(2,545	)		$	—			(1		)
	U.S. Treasury futures contracts - short position		$	(783	)		(3,838	)		4,621			$	—			(90		)
	Markit IOS total return swaps, net		$	(165	)		—			165			$	—			—
																	$	(1,342	)
	______________________
	1	Excludes a net gain of $17 million on interest-only and principal-only securities and a net loss of $28 million from debt of consolidated VIEs recognized in gain (loss) on derivative instruments and other securities, net in our consolidated statements of comprehensive income.
	The tables below summarize the effect of derivative instruments on our consolidated statements of comprehensive income for fiscal years 2013, 2012 and 2011 related to our derivative and other hedging instruments (in millions):
			Fiscal year 2013
	Derivative and Other Hedging Instruments		Notional Amount				Additions			Settlement, Termination,			Notional Amount Long/(Short) December 31, 2013				Amount of
			Long/(Short)							Expiration or							Gain/(Loss)
			31-Dec-12							Exercise							Recognized in
																	Income on
																	Derivatives 1
	Net TBA and forward settling agency securities		$	12,477			42,707			(53,065	)		$	2,119			$	(726	)
	Interest rate swaps		$	(46,850	)		(20,750	)		24,350			$	(43,250	)		1,145
	Payer swaptions		$	(14,450	)		(23,800	)		24,000			$	(14,250	)		258
	U.S. Treasury securities - short position		$	(11,835	)		(31,941	)		41,769			$	(2,007	)		472
	U.S. Treasury securities - long position		$	—			27,805			(23,878	)		$	3,927			(42		)
	U.S. Treasury futures contracts - short position		$	—			(9,239	)		7,359			$	(1,880	)		49
	TBA put option		$	—			(50	)		50			$	—			—
																	$	1,156
	________________________________
	1	Excludes a net gain of $2 million from investments in REIT equity securities,
			Fiscal year 2011
	Derivative and Other Hedging Instruments 1		Notional Amount				Additions			Additions Due to Hedge De-Designations			Settlement, Termination,			Notional Amount Long/(Short) December 31, 2011				Amount of
			Long/(Short) December 31, 2010										Expiration or							Gain/(Loss)
													Exercise							Recognized in
																				Income on
																				Derivatives 2
	Net TBA and forward settling agency securities		$	(849	)		(48,589	)		—			49,334			$	(104	)		$	(142	)
	Interest rate swaps		$	(50	)		(6,750	)		(23,900	)		450			$	(30,250	)		(119		)
	Payer swaptions		$	(850	)		(5,350	)		—			3,000			$	(3,200	)		(64		)
	U.S. Treasury securities - short position		$	(250	)		(15,794	)		—			15,164			$	(880	)		(133		)
	U.S. Treasury securities - long position		$	—			5,140			—			(5,040	)		$	100			34
	U.S. Treasury futures contracts - short position, net		$	—			(1,083	)		—			300			$	(783	)		(12		)
	TBA put option		$	—			(200	)		—			200			$	—			1
	Markit IOS total return swaps, net		$	—			510			—			(675	)		$	(165	)		7
																				$	(428	)
	________________________________
	1	Table excludes activity related to interest rate swaps designated as hedging instruments under ASC 815 prior to our discontinuation of hedge accounting in September 2011.
	2	Excludes a net loss of $17 million from interest and principal-only securities and a net loss of $2 million for hedge ineffectiveness
Not Designated as Hedging Instrument [Member]	'
Derivative [Line Items]	'
Schedule Of Interest Rate Swap Agreement By Remaining Maturity	'
	The following tables summarize our interest rate swap agreements outstanding as of December 31, 2013 and 2012 (dollars in millions):
			31-Dec-13
	Payer Interest Rate Swaps		Notional				Average			Average			Net				Average
			Amount 1				Fixed			Receive			Estimated				Maturity
							Pay Rate 2			Rate 3			Fair Value				(Years) 4
	≤ 3 years		$	16,750			1.57	%		0.19	%		$	(382	)		1.6
	> 3 to ≤ 5 years		10,225				1.07	%		0.24	%		81				3.9
	> 5 to ≤ 7 years		5,700				1.97	%		0.26	%		113				6
	> 7 to ≤ 10 years		8,825				2.28	%		0.24	%		499				8.8
	> 10 years		1,750				2.79	%		0.24	%		169				14.7
	Total Payer Interest Rate Swaps		$	43,250			1.7	%		0.22	%		$	480			4.7
	________________________
	1	Notional amount includes forward starting swaps of $4.0 billion with an average forward start date of 1.9 years from December 31, 2013.
	2	Average fixed pay rate includes forward starting swaps. Excluding forward starting swaps, the average fixed pay rate was 1.57% as of December 31, 2013.
	3	Average receive rate excludes forward starting swaps.
	4	Average maturity measured from December 31, 2013 through stated maturity date.
			December 31, 2012
	Payer Interest Rate Swaps 1		Notional				Average		Average		Net				Average
			Amount				Fixed		Receive		Estimated				Maturity
							Pay Rate		Rate		Fair Value				(Years)
	≤ 3 years		$	14,600			1.23%		0.26%		$	(294	)		2
	> 3 to ≤ 5 years		20,250				1.48%		0.29%		(666		)		4.1
	> 5 to ≤ 7 years		5,600				1.53%		0.34%		(163		)		6.1
	> 7 to ≤ 10 years		5,200				1.89%		0.35%		(113		)		9.2
	> 10 years		1,200				1.79%		0.31%		7				10.2
	Total Payer Interest Rate Swaps		$	46,850			1.46%		0.29%		$	(1,229	)		4.4
	________________________
	1	Amounts include forward starting swaps of $1.7 billion ranging up to four months from December 31, 2012.

Offsetting_Assets_and_Liabilit1

Offsetting Assets and Liabilities (Tables)	12 Months Ended
	Dec. 31, 2013
Offsetting Liabilities [Line Items]	'
Offsetting Liabilities [Table Text Block]	'
			Offsetting of Financial Liabilities and Derivative Liabilities
			Gross Amounts of Recognized Liabilities		Gross Amounts Offset in the Consolidated Balance Sheets		Net Amounts of Liabilities Presented in the Consolidated Balance Sheets		Gross Amounts Not Offset						Net Amount
									in the
									Consolidated Balance Sheets
									Financial Instruments			Collateral Pledged 2
	31-Dec-13
	Interest rate swap agreements, at fair value 1		$	400	$	—	$	400	$	(331	)	$	(69	)	$	—
	Repurchase agreements		63,533		—		63,533		(1,881		)	(61,652		)	—
	Total derivative, other hedging instruments and other liabilities		$	63,933	$	—	$	63,933	$	(2,212	)	$	(61,721	)	$	—
	31-Dec-12
	Interest rate swap agreements, at fair value 1		$	1,243	$	—	$	1,243	$	(185	)	$	(1,058	)	$	—
	Repurchase agreements		74,478		—		74,478		(10,482		)	(63,996		)	—
	Total derivative, other hedging instruments and other liabilities		$	75,721	$	—	$	75,721	$	(10,667	)	$	(65,054	)	$	—
	_______________________
	1	Reported under derivative assets / liabilities, at fair value in the accompanying consolidated balance sheets. Refer to Note 5 for a reconciliation of derivative assets / liabilities, at fair value to their sub-components.
	2	Includes cash and securities received / pledged as collateral, at fair value. Amounts presented are limited to collateral pledged sufficient to reduce the net amount to zero for individual counterparties, as applicable. Refer to Note 3 for additional information regarding assets pledged as collateral.
Offsetting Assets and Liabilities [Table Text Block]	'
	The following tables present information about our assets and liabilities that are subject to such arrangements and can potentially be offset on our consolidated balance sheets as of December 31, 2013 and 2012 (in millions):
			Offsetting of Financial Assets and Derivative Assets
			Gross Amounts of Recognized Assets		Gross Amounts Offset in the Consolidated Balance Sheets		Net Amounts of Assets Presented in the Consolidated Balance Sheets		Gross Amounts Not Offset						Net Amount
									in the
									Consolidated Balance Sheets
									Financial Instruments			Collateral Received 2
	31-Dec-13
	Interest rate swap and swaption agreements, at fair value 1		$	1,138	$	—	$	1,138	$	(331	)	$	(610	)	$	197
	Receivable under reverse repurchase agreements		1,881		—		1,881		(1,881		)	—			—
	Total derivative, other hedging instruments and other assets		$	3,019	$	—	$	3,019	$	(2,212	)	$	(610	)	$	197
	31-Dec-12
	Interest rate swap and swaption agreements, at fair value 1		$	185	$	—	$	185	$	(185	)	$	—		$	—
	Receivable under reverse repurchase agreements		11,818		—		11,818		(10,482		)	(1,157		)	179
	Total derivative, other hedging instruments and other assets		$	12,003	$	—	$	12,003	$	(10,667	)	$	(1,157	)	$	179

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis	'
	The following table provides a summary of our assets and liabilities that are measured at fair value on a recurring basis as of December 31, 2013 and 2012 (dollars in millions):
		Fair Value Hierarchy
		Level 1		Level 2		Level 3
	December 31, 2013
	Assets:
	Agency securities	$	—	$	65,941	$	—
	U.S. Treasury securities	3,822		—		—
	Interest rate swaps	—		880		—
	Payer swaptions	—		258		—
	REIT equity securities	237		—
	U.S. Treasury futures	39		—		—
	Net TBA and forward settling agency securities	—		17		—
	Total	$	4,098	$	67,096	$	—
	Liabilities:
	Debt of consolidated VIEs	$	—	$	910	$	—
	Obligation to return U.S. Treasury securities borrowed under reverse repurchase agreements	1,848		—		—
	Interest rate swaps	—		400		—
	Net TBA and forward settling agency securities	—		22		—
	Total	$	1,848	$	1,332	$	—
	December 31, 2012
	Assets:
	Agency securities	$	—	$	85,245	$	—
	Interest rate swaps	—		14		—
	Payer swaptions	—		171		—
	Net TBA and forward settling agency securities	—		116		—
	Total	$	—	$	85,546	$	—
	Liabilities:
	Debt of consolidated VIEs	$	—	$	937	$	—
	Obligation to return U.S. Treasury securities borrowed under reverse repurchase agreements	11,763		—		—
	Interest rate swaps	—		1,243		—
	Net TBA and forward settling agency securities	—		21		—
	Total	$	11,763	$	2,201	$	—

Income_Taxes_Tables

Income Taxes (Tables) (USD $)	12 Months Ended
In Millions, except Per Share data, unless otherwise specified	Dec. 31, 2013											Dec. 31, 2012	Dec. 31, 2011
Schedule of Dividends Paid [Line Items]	'											'	'
Dividends Declared [Table Text Block]	'											'	'
	The following table summarizes dividends for federal income tax purposes declared for fiscal years 2013, 2012 and 2011 and their related tax characterization (in millions, except per share amounts):
						Tax Characterization
	Fiscal Tax Year	Dividends Declared Per Share		Dividends Declared		Ordinary Income Per Share		Qualified Dividends		Long-Term Capital Gains Per Share
	Series A Cumulative Redeemable Preferred Stock Dividends
	Fiscal year 2013	$	2	$	14	$	2	$	0.01598	$	—
	Fiscal year 2012	$	1.056	$	7	$	0.9523	$	—	$	0.1037
	Common Stock Dividends
	Fiscal year 2013	$	3.75	$	1,453	$	3.75	$	0.029963	$	—
	Fiscal year 2012	$	5	$	1,518	$	4.5092	$	—	$	0.4908
	Fiscal year 2011	$	5.6	$	886	$	5.3324	$	—	$	0.2676
Preferred Stock, Dividend Rate, Per-Dollar-Amount	$2											$1.06	'
Common Stock, Dividends, Per Share, Cash Paid	$3.75											$5	$5.60
Dividends, Common Stock	$1,453											$1,518	$886
Dividends, Preferred Stock	$14											$7	'
Qualified Dividends Per Share [Member]	'											'	'
Schedule of Dividends Paid [Line Items]	'											'	'
Preferred Stock, Dividend Rate, Per-Dollar-Amount	$0.02											'	'
Common Stock, Dividends, Per Share, Cash Paid	$0.03											'	'
Ordinary Income Per Share [Member]	'											'	'
Schedule of Dividends Paid [Line Items]	'											'	'
Preferred Stock, Dividend Rate, Per-Dollar-Amount	$2											$0.95	'
Common Stock, Dividends, Per Share, Cash Paid	$3.75											$4.51	$5.33
Long term Capital Gain [Member]	'											'	'
Schedule of Dividends Paid [Line Items]	'											'	'
Preferred Stock, Dividend Rate, Per-Dollar-Amount	'											$0.10	'
Common Stock, Dividends, Per Share, Cash Paid	'											$0.49	$0.27

Stockholders_Equity_Equity_Off

Stockholders' Equity Equity Offerings (Tables)	12 Months Ended
	Dec. 31, 2013
Class of Stock [Line Items]	'
Schedule of Stock by Class [Table Text Block]	'
	The table below summarizes sales our common stock under such sales agreements during fiscal years 2012 and 2011 (in millions, except per share amounts):
	At-the-Market Offering		Price Received			Shares			Net Proceeds
			Per Share
	Fiscal year 2012		$	31.41		9.5			$	298
	Fiscal year 2011		$	29.25		9.4			$	273
	During fiscal years 2013, 2012 and 2011, we completed follow-on public offerings of shares of our common stock summarized in the table below (in millions, except per share amounts):
	Public Offering		Price Received		Shares		Net Proceeds 2
			Per Share 1
	Fiscal year 2013
	Mar-13		$31.34		57.5		$	1,803
	Total fiscal year 2013				57.5		$	1,803
	Fiscal year 2012
	Mar-12		$29.00		71.2		$	2,063
	Jul-12		$33.70		36.8		1,240
	Total fiscal year 2012				108		$	3,303
	Fiscal year 2011
	Jan-11		$28.00		26.9		$	719
	Mar-11		$27.72		32.2		892
	Jun-11		$27.56		49.7		1,369
	Nov-11		$27.36		40.5		1,108
	Total fiscal year 2011				149.3		$	4,088
	________________________
	1	Price received per share is gross of underwriters' discount, if applicable, and other offering costs.
	2	Net proceeds are net of the underwriters' discount, if applicable, and other offering costs.
Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block]	'
	The following table summarizes changes to accumulated OCI for fiscal years 2013, 2012 and 2011 (in millions):
	Accumulated Other Comprehensive (Loss) Income		Net Unrealized Gain (Loss) on Available-for-Sale MBS			Net Unrealized Gain (Loss) on Swaps				Total Accumulated OCI
										Balance
	Balance as of December 31, 2010		$	(28	)	$	(40	)		$	(68	)
	OCI before reclassifications		1,512			(844		)		668
	Amounts reclassified from accumulated OCI		(483		)	194				(289		)
	Balance as of December 31, 2011		1,001			(690		)		311
	OCI before reclassifications		2,235			—				2,235
	Amounts reclassified from accumulated OCI		(1,196		)	205				(991		)
	Balance as of December 31, 2012		2,040			(485		)		1,555
	OCI before reclassifications		(4,535		)	—				(4,535		)
	Amounts reclassified from accumulated OCI		1,408			189				1,597
	Balance as of December 31, 2013		$	(1,087	)	$	(296	)		$	(1,383	)
	The following table summarizes reclassifications out of accumulated OCI for fiscal years 2013, 2012 and 2011 (in millions):
			Fiscal Year
	Amounts Reclassified from Accumulated OCI		2013			2012				2011			Line Item in the Consolidated
													Statements of Comprehensive Income
													Where Net Income is Presented
	(Gain) loss amounts reclassified from accumulated OCI for available-for-sale MBS		$	1,408		$	(1,196	)		$	(483	)	Gain (loss) on sale of agency securities, net
	Periodic interest costs of interest rate swaps previously designated as hedges under GAAP, net		189			205				194			Interest expense
	Total reclassifications		$	1,597		$	(991	)		$	(289	)

Quarterly_Results_Tables

Quarterly Results (Tables)	12 Months Ended
	Dec. 31, 2013
Schedule of Quarterly Financial Information [Table Text Block]	'
	The following is a presentation of the quarterly results of operations and comprehensive income for fiscal years 2013 and 2012 (in millions, except per share data).
		Quarter Ended
		March 31,			June 30,			September 30,			31-Dec-13
		2013			2013			2013
	Interest income:
	Interest income	$	547		$	545		$	558		$	542
	Interest expense	140			131			145			120
	Net interest income	407			414			413			422
	Other (loss) income:
	(Loss) gain on sale of agency securities, net	(26		)	17			(733		)	(667		)
	(Loss) gain on derivative instruments and other securities, net	(98		)	1,444			(339		)	184
	Total other (loss) income, net	(124		)	1,461			(1,072		)	(483		)
	Expenses:
	Management fees	33			37			35			31
	General and administrative expenses	9			9			7			6
	Total expenses	42			46			42			37
	Income (loss) before income tax	241			1,829			(701		)	(98		)
	Provision for income tax, net	10			—			—			3
	Net income (loss)	231			1,829			(701		)	(101		)
	Dividend on preferred stock	3			3			3			3
	Net income (loss) available (attributable) to common shareholders	$	228		$	1,826		$	(704	)	$	(104	)
	Net income (loss)	$	231		$	1,829		$	(701	)	$	(101	)
	Other comprehensive (loss) income:
	Unrealized (loss) gain on available-for-sale securities, net	(837		)	(2,813		)	833			(311		)
	Unrealized gain on derivative instruments, net	49			48			47			46
	Other comprehensive (loss) income	(788		)	(2,765		)	880			(265		)
	Comprehensive (loss) income	(557		)	(936		)	179			(366		)
	Dividend on preferred stock	3			3			3			3
	Comprehensive (loss) income (attributable) available to common shareholders	$	(560	)	$	(939	)	$	176		$	(369	)
	Weighted average number of common shares outstanding-basic and diluted	356.2			396.4			390.6			373
	Net income (loss) per common share - basic and diluted	$	0.64		$	4.61		$	(1.80	)	$	(0.28	)
	Comprehensive (loss) income per common share - basic and diluted	$	(1.57	)	$	(2.37	)	$	0.45		$	(0.99	)
	Dividends declared per common share	$	1.25		$	1.05		$	0.8		$	0.65
		Quarter Ended
		March 31,			June 30,			September 30,			December 31,
		2012			2012			2012			2012
	Interest income:
	Interest income	$	514		$	504		$	520		$	570
	Interest expense	106			120			139			147
	Net interest income	408			384			381			423
	Other income (loss):
	Gain on sale of agency securities, net	216			417			210			353
	Gain (loss) on derivative instruments and other securities, net	47			(1,029		)	(460		)	89
	Total other income (loss), net	263			(612		)	(250		)	442
	Expenses:
	Management fees	22			28			32			31
	General and administrative expenses	6			8			8			9
	Total expenses	28			36			40			40
	Income (loss) before taxes	643			(264		)	91			825
	Income tax provision (benefit)	2			(3		)	5			15
	Net income (loss)	$	641		$	(261	)	$	86		$	810
	Dividend on preferred stock	—			3			3			3
	Net income (loss) available (attributable) to common shareholders	$	641		$	(264	)	$	83		$	807
	Net income (loss)	$	641		$	(261	)	$	86		$	810
	Other comprehensive (loss) income:
	Unrealized (loss) gain on available-for-sale securities, net	(106		)	689			1,190			(734		)
	Unrealized gain on derivative instruments, net	52			52			51			50
	Other comprehensive (loss) income	(54		)	741			1,241			(684		)
	Comprehensive income	587			480			1,327			126
	Dividend on preferred stock	—			3			3			3
	Comprehensive (loss) income (attributable) available to common shareholders	$	587		$	477		$	1,324		$	123
	Weighted average number of common shares outstanding-basic and diluted	240.6			301			332.8			340.3
	Net income (loss) per common share - basic and diluted	$	2.66		$	(0.88	)	$	0.25		$	2.37
Comprehensive income per common share - basic and diluted	$	2.44		$	1.58		$	3.98		$	0.36
Dividends declared per common share	$	1.25		$	1.25		$	1.25		$	1.25

Organization_Details

Organization (Details)	12 Months Ended
	Dec. 31, 2013
Organization [Abstract]	'
Required distribution of taxable net income on a annual basis	90.00%
Intended Annual Distribution of Taxable Net Income	100.00%

Summary_of_Significant_Account2

Summary of Significant Accounting Policies (Details)	12 Months Ended
	Dec. 31, 2013
New Accounting Pronouncements or Change in Accounting Principle [Line Items]	'
REIT Capital Gain Distribution %	95.00%
Required Annual Distribution of Taxable Net Income	90.00%
REIT Ordinary Income Distribution %	85.00%
Excise Tax Rate	4.00%

Investment_Securities_Narrativ

Investment Securities (Narrative) (Details) (USD $)	12 Months Ended				12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
	years	years	Agency Securities [Member]	Agency Securities [Member]	Interest Only And Principal Only Strip [Member]
Schedule of Available-for-sale Securities [Line Items]	'	'	'	'	'
Trading Securities, Realized Gain (Loss)	'	'	'	'	($10,000,000)
Debt Instrument, Unamortized Discount (Premium), Net	'	'	3,000,000,000	4,400,000,000	'
Gain Loss on Other Debt	39,000,000	-28,000,000	'	'	'
Future Prepayment Rate Assumption Of Investment Portfolio	7.00%	11.00%	'	'	'
Weighted Average Life of Interest Only Securities	6.3	5.7	'	'	'
Weighted Average Life Of Principal Only Securities	8.6	6.4	'	'	'
Fair value of CMO securities and interest-only strips	1,700,000,000	719,000,000	'	'	'
Securitized CMO Securities	2,300,000,000	1,300,000,000	'	'	'
CMO and Interest Only, Pricincipal Only Securities, Maximum Loss Exposure	246,000,000	343,000,000	'	'	'
Fair value of agency securities collaterizing debt issued by securitization trust	1,500,000,000	'	'	'	'
Principal balance of agency securities collaterizing debt issued by securitization trust	1,400,000,000	'	'	'	'
Debt Instrument, Face Amount	900,000,000	908,000,000	'	'	'
Other Long-term Debt	$910,000,000	$937,000,000	'	'	'

Investment_Securities_Summary_

Investment Securities (Summary of Investment in Agency Security) (Details) (USD $)	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2012
Amortized cost	$66,593,000,000		$82,652,000,000
Total agency MBS, at fair value	65,941,000,000		85,245,000,000
Weighted average coupon	3.58%	[1]	3.69%	[1]
Weighted average yield	2.70%	[2]	2.61%	[2]
Weighted average yield for the year ended	2.77%	[2]	2.82%	[2]
Unamortized principal balance of interest-only strips	1,400,000,000		1,700,000,000
Unamortized principal balance of principal-only strips	271,000,000		302,000,000
Weighted average contractual interest rate of interest only strips	5.50%		5.78%
Average prepayment rate based on forward rate assumption	7.00%		11.00%
Federal National Mortgage Association Certificates and Obligations (FNMA) [Member]	'		'
Total agency MBS, at fair value	52,693,000,000		64,190,000,000
Weighted average coupon	3.53%	[1]	3.70%	[1]
Weighted average yield	2.66%	[2]	2.62%	[2]
Weighted average yield for the year ended	2.74%	[2]	2.83%	[2]
Federal Home Loan Mortgage Corporation Certificates and Obligations (FHLMC) [Member]	'		'
Total agency MBS, at fair value	13,013,000,000		20,801,000,000
Weighted average coupon	3.78%	[1]	3.67%	[1]
Weighted average yield	2.87%	[2]	2.61%	[2]
Weighted average yield for the year ended	2.87%	[2]	2.83%	[2]
Government National Mortgage Association Certificates and Obligations (GNMA) [Member]	'		'
Total agency MBS, at fair value	235,000,000		254,000,000
Weighted average coupon	3.56%	[1]	3.77%	[1]
Weighted average yield	1.66%	[2]	1.60%	[2]
Weighted average yield for the year ended	1.79%	[2]	1.63%	[2]
Available-for-sale Securities [Member]	'		'
Agency MBS, par	63,777,000,000		78,486,000,000
Unamortized discount	32,000,000		'
Unamortized premium	2,848,000,000		4,166,000,000
Amortized cost	66,593,000,000		82,652,000,000
Gross unrealized gains	260,000,000		2,072,000,000
Gross unrealized losses	1,349,000,000		25,000,000
Total available-for-sale agency MBS, at fair value	65,504,000,000		84,699,000,000
Available-for-sale Securities [Member] | Federal National Mortgage Association Certificates and Obligations (FNMA) [Member]	'		'
Agency MBS, par	50,914,000,000		58,912,000,000
Unamortized discount	25,000,000		'
Unamortized premium	2,210,000,000		3,208,000,000
Amortized cost	53,099,000,000		62,120,000,000
Gross unrealized gains	181,000,000		1,585,000,000
Gross unrealized losses	991,000,000		18,000,000
Total available-for-sale agency MBS, at fair value	52,289,000,000		63,687,000,000
Available-for-sale Securities [Member] | Federal Home Loan Mortgage Corporation Certificates and Obligations (FHLMC) [Member]	'		'
Agency MBS, par	12,640,000,000		19,336,000,000
Unamortized discount	7,000,000		'
Unamortized premium	631,000,000		948,000,000
Amortized cost	13,264,000,000		20,284,000,000
Gross unrealized gains	74,000,000		481,000,000
Gross unrealized losses	358,000,000		7,000,000
Total available-for-sale agency MBS, at fair value	12,980,000,000		20,758,000,000
Available-for-sale Securities [Member] | Government National Mortgage Association Certificates and Obligations (GNMA) [Member]	'		'
Agency MBS, par	223,000,000		238,000,000
Unamortized discount	0		'
Unamortized premium	7,000,000		10,000,000
Amortized cost	230,000,000		248,000,000
Gross unrealized gains	5,000,000		6,000,000
Gross unrealized losses	0		0
Total available-for-sale agency MBS, at fair value	235,000,000		254,000,000
Agency MBS remeasured at fair value through earnings [Member]	'		'
Interest-only and principal-only strips, amortized cost	432,000,000		541,000,000
Gross unrealized gains	16,000,000		27,000,000
Gross unrealized losses	-11,000,000		-22,000,000
Total agency MBS remeasured at fair value through earnings, at fair value	437,000,000		546,000,000
Agency MBS remeasured at fair value through earnings [Member] | Federal National Mortgage Association Certificates and Obligations (FNMA) [Member]	'		'
Interest-only and principal-only strips, amortized cost	400,000,000		486,000,000
Gross unrealized gains	13,000,000		26,000,000
Gross unrealized losses	-9,000,000		-9,000,000
Total agency MBS remeasured at fair value through earnings, at fair value	404,000,000		503,000,000
Agency MBS remeasured at fair value through earnings [Member] | Federal Home Loan Mortgage Corporation Certificates and Obligations (FHLMC) [Member]	'		'
Interest-only and principal-only strips, amortized cost	32,000,000		55,000,000
Gross unrealized gains	3,000,000		1,000,000
Gross unrealized losses	-2,000,000		-13,000,000
Total agency MBS remeasured at fair value through earnings, at fair value	33,000,000		43,000,000
Agency MBS remeasured at fair value through earnings [Member] | Government National Mortgage Association Certificates and Obligations (GNMA) [Member]	'		'
Interest-only and principal-only strips, amortized cost	0		0
Gross unrealized gains	0		0
Gross unrealized losses	0		0
Total agency MBS remeasured at fair value through earnings, at fair value	$0		$0
[1]	The underlying unamortized principal balance ("UPB" or "par value") of our interest-only agency MBS strips was $1.4 billion and the weighted average contractual interest we are entitled to receive was 5.50% of this amount as of DecemberB 31, 2013. The par value of our principal-only agency MBS strips was $271 million as of DecemberB 31, 2013.
[2]	Incorporates a weighted average future constant prepayment rate assumption of 7% based on forward rates as of DecemberB 31, 2013

Investment_Securities_Componen

Investment Securities (Components Of Investment Securities) (Details) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Millions, unless otherwise specified
Amortized cost	$67,025	$83,193
Gross unrealized gains	276	2,099
Gross unrealized losses	-1,360	-47
Available-for-sale Securities, Fair Value Disclosure	65,504	84,699
Available-for-sale Securities, Amortized Cost Basis	66,593	82,652
Total agency MBS, at fair value	65,941	85,245
Total Agency Securities	65,941	85,245
Fixed-Rate [Member]	'	'
Gross unrealized gains	242	2,043
Gross unrealized losses	-1,338	-25
Available-for-sale Securities, Fair Value Disclosure	62,961	83,635
Adjustable-Rate [Member]	'	'
Gross unrealized gains	15	26
Gross unrealized losses	-3	0
Available-for-sale Securities, Fair Value Disclosure	1,235	891
CMO [Member]	'	'
Gross unrealized gains	3	3
Gross unrealized losses	-8	0
Available-for-sale Securities, Fair Value Disclosure	1,308	173
Agency Securities [Member] | Fixed-Rate [Member]	'	'
Available-for-sale Securities, Amortized Cost Basis	64,057	81,617
Agency Securities [Member] | Adjustable-Rate [Member]	'	'
Available-for-sale Securities, Amortized Cost Basis	1,223	865
Agency Securities [Member] | CMO [Member]	'	'
Available-for-sale Securities, Amortized Cost Basis	1,313	170
Agency Securities [Member] | Interest Only And Principal Only Strip [Member]	'	'
Amortized cost	432	541
Gross unrealized gains	16	27
Gross unrealized losses	-11	-22
Fair Value	$437	$546

Investment_Securities_Summary_1

Investment Securities (Summary Of Agency Securities Estimated Weighted Average Life Classifications) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
	years	years
Weighted Average Life of Interest Only Securities	6.3	5.7
Agency securities classified as available for sale, Fair value	$65,504	$84,699
Agency securities classified as available for sale, Amortized cost	66,593	82,652
Weighted average coupon	3.47%	3.59%
Available For Sale Securities Weighted Average Life yield	2.68%	2.59%
Weighted Average Life Of Principal Only Securities	8.6	6.4
Less Than or Equal to One Year [Member]	'	'
Available For Sale Securities Weighted Average Life Fair Value	129	'
Available For Sale Securities Weighted Average Life Amortized Cost	129	'
Weighted average coupon	3.07%	'
Available For Sale Securities Weighted Average Life yield	2.53%	'
Greater Than One Year and Less Than or Equal to Three Years [Member]	'	'
Available For Sale Securities Weighted Average Life Fair Value	498	1,119
Available For Sale Securities Weighted Average Life Amortized Cost	491	1,108
Weighted average coupon	4.08%	4.18%
Available For Sale Securities Weighted Average Life yield	2.25%	2.14%
Greater Than Three Years and Less Than or Equal to Five Years [Member]	'	'
Available For Sale Securities Weighted Average Life Fair Value	24,471	27,448
Available For Sale Securities Weighted Average Life Amortized Cost	24,342	26,750
Weighted average coupon	3.59%	3.36%
Available For Sale Securities Weighted Average Life yield	2.57%	2.29%
Greater Than Five Years [Member]	'	'
Available For Sale Securities Weighted Average Life Fair Value	38,522	54,054
Available For Sale Securities Weighted Average Life Amortized Cost	39,635	52,735
Weighted average coupon	3.39%	3.69%
Available For Sale Securities Weighted Average Life yield	2.73%	2.75%
Greater Than Ten Years [Member]	'	'
Available For Sale Securities Weighted Average Life Fair Value	1,884	2,078
Available For Sale Securities Weighted Average Life Amortized Cost	$1,996	$2,059
Weighted average coupon	3.66%	3.44%
Available For Sale Securities Weighted Average Life yield	2.96%	2.65%

Investment_Securities_Summary_2

Investment Securities (Summary Of Changes In Accumulated OCI For Available-For-Sale Security) (Details) (USD $)

3 Months Ended

12 Months Ended

9 Months Ended

12 Months Ended

In Millions, unless otherwise specified

Dec. 31, 2013

Sep. 30, 2013

Jun. 30, 2013

Mar. 31, 2013

Dec. 31, 2012

Sep. 30, 2012

Jun. 30, 2012

Mar. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Sep. 30, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Agency Securities [Member]

Agency Securities [Member]

Agency Securities [Member]

Agency Securities [Member]

Accumulated Other Comprehensive Income (Loss) [Roll Forward]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Beginning OCI Balance

'

'

'

'

'

'

'

'

'

'

'

$1,001

$2,040

$1,001

($28)

Unrealized gain (loss) on available-for-sale securities, net

-311

833

-2,813

-837

-734

1,190

689

-106

-3,127

1,039

1,029

2,235

-4,535

2,235

1,512

Reversal of prior Period Unrealized (Gains) and Losses, Net on Realization

'

'

'

'

'

'

'

'

'

'

'

1,196

-1,408

1,196

483

Ending OCI Balance

'

'

'

'

'

'

'

'

'

'

'

'

($1,087)

$2,040

$1,001

Investment_Securities_Summary_3

Investment Securities (Summary Of Continuous Unrealized Loss Positions Of Available-For-Sale Security) (Details) (Accumulated Other Comprehensive Income (Loss) [Member], USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Accumulated Other Comprehensive Income (Loss) [Member]	'	'
Unrealized Loss Position For - Estimated Fair Value - Less than 12 Months	$42,853	$8,430
Unrealized Loss Position For - Unrealized Loss - Less than 12 Months	1,248	25
Unrealized Loss Position For - Estimated Fair Value - 12 Months or More	1,586	0
Unrealized Loss Position For - Unrealized Loss - 12 Months or More	-101	0
Unrealized Loss Position For - Estimated Fair Value - Total	44,439	8,430
Unrealized Loss Position For - Unrealized Loss - Total	($1,349)	($25)

Investment_Securities_Summary_4

Investment Securities (Summary Of Net Gain From Sale Of Agency Securities) (Details) (USD $)	3 Months Ended								12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Proceeds from agency MBS sold	'	'	'	'	'	'	'	'	($54,952)	($39,012)	($22,397)
Gain (Loss) on Sales of Mortgage Backed Securities (MBS)	-667	-733	17	-26	353	210	417	216	-1,408	1,196	473
Agency Securities [Member]	'	'	'	'	'	'	'	'	'	'	'
Agency MBS sold, at cost	'	'	'	'	'	'	'	'	81,516	63,610	37,579
Proceeds from agency MBS sold	'	'	'	'	'	'	'	'	-80,108	-64,806	-38,052
Gain (Loss) on Sales of Mortgage Backed Securities (MBS)	'	'	'	'	'	'	'	'	-1,408	1,196	473
Gross gains on sale of agency MBS	'	'	'	'	'	'	'	'	217	1,209	510
Gross losses on sale of agency MBS	'	'	'	'	'	'	'	'	$1,625	$13	$37

Investment_Securities_Summary_5

Investment Securities (Summary Of Agency Securities Pledged As Collateral Under Repurchase, Other Debt, Derivative And Prime Broker Agreements) (Details) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Millions, unless otherwise specified
Fair value	$62,205	$79,966
Accrued interest on pledged agency securities	195	226
Restricted Cash and Cash Equivalents	101	399
Total Fair Value Of Agency Securities Pledged And Accrued Interest	68,360	82,126
US Treasury Securities [Member]	'	'
Fair value	3,778	'
Repurchase Agreements [Member]	'	'
Accrued interest on pledged agency securities	189	217
Total Fair Value Of Agency Securities Pledged And Accrued Interest	66,608	78,617
Under Repurchase Agreements [Member]	'	'
Fair value	1,459	1,535
Accrued interest on pledged agency securities	5	5
Total Fair Value Of Agency Securities Pledged And Accrued Interest	1,464	1,540
Under Prime Broker Agreements [Member]	'	'
Fair value	91	501
Accrued interest on pledged agency securities	0	1
Total Fair Value Of Agency Securities Pledged And Accrued Interest	148	652
Includes Sold But Not Yet Settled Securities [Member]	'	'
Fair value	64,286	81,501
Derivative [Member]	'	'
Fair value	'	1,065
Accrued interest on pledged agency securities	'	3
Total Fair Value Of Agency Securities Pledged And Accrued Interest	'	1,317
Derivative [Member]	'	'
Fair value	28	'
Accrued interest on pledged agency securities	1	'
Restricted Cash and Cash Equivalents	41	'
Total Fair Value Of Agency Securities Pledged And Accrued Interest	140	'
Derivative [Member] | US Treasury Securities [Member]	'	'
Fair value	70	'
Repurchase Agreements [Member]	'	'
Fair value	62,708	78,400
Repurchase Agreements [Member] | US Treasury Securities [Member]	'	'
Fair value	3,708	'
Derivative [Member]	'	'
Restricted Cash and Cash Equivalents	'	249
Excluding Cash Received [Member]	'	'
Restricted Cash and Cash Equivalents	101	399
Repurchase Agreements [Member]	'	'
Restricted Cash and Cash Equivalents	3	0
Under Prime Broker Agreements [Member]	'	'
Restricted Cash and Cash Equivalents	57	150
Assets Pledged to Us [Member] | Derivative [Member]	'	'
Fair value	82	'
Assets Pledged to Us [Member] | Derivative [Member] | Repurchase Agreements [Member]	'	'
Fair value	164	'
Assets Pledged to Us [Member] | Derivative [Member]	'	'
Restricted Cash and Cash Equivalents	$366	$249

Investment_Securities_Summary_6

Investment Securities (Summary Of Agency Securities Pledged As Collateral Under Repurchase Agreements By Remaining Maturity) (Details) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Millions, unless otherwise specified
Amortized cost	$69,008	$78,003
Accrued Interest on pledged agency securities	194	222
Available-for-sale Securities Pledged as Collateral	62,205	79,966
Security Owned and Pledged as Collateral, Fair Value	67,875	79,935
Trading Securities Pledged as Collateral	3,778	'
30 Days or Less [Member]	'	'
Amortized cost	28,125	28,525
Accrued Interest on pledged agency securities	76	82
Security Owned and Pledged as Collateral, Fair Value	27,694	29,284
Maturity 31 To 59 Days [Member]	'	'
Amortized cost	15,210	21,251
Accrued Interest on pledged agency securities	42	58
Security Owned and Pledged as Collateral, Fair Value	14,955	21,716
Maturity 60 To 90 Days [Member]	'	'
Amortized cost	10,290	15,780
Accrued Interest on pledged agency securities	28	45
Security Owned and Pledged as Collateral, Fair Value	10,117	16,188
Greater than 90 Days [Member]	'	'
Amortized cost	11,623	12,447
Accrued Interest on pledged agency securities	32	37
Security Owned and Pledged as Collateral, Fair Value	11,401	12,747
Maturity Overnight [Member]	'	'
Amortized cost	3,760	'
Accrued Interest on pledged agency securities	16	'
Trading Securities Pledged as Collateral	3,708	'
Agency Securities [Member]	'	'
Amortized cost	65,248	'
Accrued Interest on pledged agency securities	178	'
Security Owned and Pledged as Collateral, Fair Value	64,167	79,935
Repurchase Agreements [Member]	'	'
Available-for-sale Securities Pledged as Collateral	$62,708	$78,400

Repurchase_Agreements_And_Othe1

Repurchase Agreements And Other Debt (Narrative) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
	years
Debt Instrument [Line Items]	'	'
Weighted Average Life of Other Debt	5.4	'
Secured Debt, Dollar Rolls	$2,276	$12,775
Risk of repurchase agreement to stockholders equity	4.00%	'
Other Long-term Debt	910	937
Debt Instrument, Face Amount	$900	$908
Debt Instrument, Description of Variable Rate Basis, LIBOR	'LIBOR	'
Spread Over LIBOR	'42	'43

Repurchase_Agreements_And_Othe2

Repurchase Agreements And Other Debt (Repurchase Arrangements And Weighted Average Interest Rates Classified By Original Maturities) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Spread Over LIBOR	'42	'43
Debt Instrument, Face Amount	$900	$908
Borrowings Outstanding	63,533	74,478
Weighted Average Days to Maturity	119	118
1 Month or Less	'	'
Borrowings Outstanding	23,577	25,474
Average Interest Rate	0.42%	0.48%
Weighted Average Days to Maturity	15	17
thirty one to ninety [Member]	'	'
Borrowings Outstanding	20,490	30,402
Average Interest Rate	0.43%	0.49%
Weighted Average Days to Maturity	61	57
120 to 180 days [Member]	'	'
Borrowings Outstanding	6,946	7,208
Average Interest Rate	0.45%	0.53%
Weighted Average Days to Maturity	140	128
210 to 270 days [Member]	'	'
Borrowings Outstanding	2,232	4,509
Average Interest Rate	0.53%	0.57%
Weighted Average Days to Maturity	230	234
300 to 360 days [Member]	'	'
Borrowings Outstanding	3,607	2,149
Average Interest Rate	0.54%	0.60%
Weighted Average Days to Maturity	323	312
390 to 720 days [Member]	'	'
Borrowings Outstanding	3,261	2,142
Average Interest Rate	0.60%	0.65%
Weighted Average Days to Maturity	603	591
750 to 1080 days [Member]	'	'
Borrowings Outstanding	500	2,492
Average Interest Rate	0.62%	0.69%
Weighted Average Days to Maturity	930	1,002
Greater than 1080 days [Member]	'	'
Borrowings Outstanding	602	102
Average Interest Rate	0.68%	0.73%
Weighted Average Days to Maturity	1,468	1,751
US Treasury Securities [Member]	'	'
Borrowings Outstanding	2,318	'
Average Interest Rate	0.02%	'
Weighted Average Days to Maturity	1	'
Repurchase Agreements [Member]	'	'
Average Interest Rate	0.44%	0.51%
Agency Securities [Member]	'	'
Borrowings Outstanding	$61,215	$74,478
Weighted Average Days to Maturity	124	118
Agency Securities [Member] | Repurchase Agreements [Member]	'	'
Average Interest Rate	0.45%	0.51%

Derivative_and_Other_Hedging_I2

Derivative and Other Hedging Instruments (Narrative) (Details) (USD $)

3 Months Ended

12 Months Ended

3 Months Ended

12 Months Ended

Dec. 31, 2013

Sep. 30, 2013

Jun. 30, 2013

Mar. 31, 2013

Dec. 31, 2012

Sep. 30, 2012

Jun. 30, 2012

Mar. 31, 2012

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2011

Dec. 31, 2012

Dec. 31, 2010

Dec. 31, 2011

Dec. 31, 2013

Interest Rate Swap [Member]

Interest Rate Swap [Member]

Discontinuation of Election to Account for Interest Rate Swaps as Designated Cash Flow Hedges [Member]

Discontinuation of Election to Account for Interest Rate Swaps as Designated Cash Flow Hedges [Member]

Discontinuation of Election to Account for Interest Rate Swaps as Designated Cash Flow Hedges [Member]

Discontinuation of Election to Account for Interest Rate Swaps as Designated Cash Flow Hedges [Member]

Discontinuation of Election to Account for Interest Rate Swaps as Designated Cash Flow Hedges [Member]

Discontinuation of Election to Account for Interest Rate Swaps as Designated Cash Flow Hedges [Member]

Interest Rate Swap [Member]

Interest Rate Swaps [Member]

Derivative Instruments, Gain Reclassified from Accumulated OCI into Income, Effective Portion

'

'

'

'

'

'

'

'

'

$424,000,000

$252,000,000

$35,000,000

'

'

'

'

'

'

'

'

Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax

46,000,000

47,000,000

48,000,000

49,000,000

50,000,000

51,000,000

52,000,000

52,000,000

'

189,000,000

205,000,000

-650,000,000

'

'

189,000,000

194,000,000

'

'

54,000,000

'

Net Periodic Interest Rate Costs on Swaps

'

'

'

'

'

'

'

'

89,000,000

613,000,000

457,000,000

'

'

'

'

'

'

'

'

'

Gain On Interest Only Securities Remeasured at Fair Value Through Earnings

'

'

'

'

'

'

'

'

'

'

17,000,000

'

'

'

'

'

'

'

'

'

Deferred Gain (Loss) on Discontinuation of Interest Rate Fair Value Hedge

'

'

'

'

'

'

'

'

'

'

'

'

'

'

-296,000,000

-690,000,000

-485,000,000

-40,000,000

'

'

Derivative, Average Remaining Maturity

'

'

'

'

'

'

'

'

'

'

'

'

'4 years 8 months

'4 years 5 months 0 days

'

'

'

'

'

'2 years 1 month 20 days

Fair Value of Derivative Instruments

-5,000,000

'

'

'

95,000,000

'

'

'

'

-5,000,000

95,000,000

'

'

'

'

'

'

'

'

'

Obligation to return securities borrowed under reverse repurchase agreements, at fair value

1,848,000,000

'

'

'

11,763,000,000

'

'

'

'

1,848,000,000

11,763,000,000

'

'

'

'

'

'

'

'

'

Proceeds from sales of treasury securities

'

'

'

'

'

'

'

'

'

1,900,000,000

11,700,000,000

'

'

'

'

'

'

'

'

'

Deferred gain loss discontinued interest rate swap expected to be reclassified from OCI to interest expense next twelve months

'

'

'

'

'

'

'

'

'

'

'

'

'

'

156,000,000

'

'

'

'

'

Interest rate swap agreement outstanding not designated as hedge

'

'

'

'

'

'

'

'

'

'

'

'

43,250,000,000

46,850,000,000

'

'

'

'

'

'

Gain on interest only securities remeasured at fair value through earnings

'

'

'

'

'

'

'

'

'

0

'

-17,000,000

'

'

'

'

'

'

'

'

Loss on Interest Only Securities Remeasured at Fair Value Through Earnings

'

'

'

'

'

'

'

'

'

0

'

-17,000,000

'

'

'

'

'

'

'

'

Credit Derivative, Maximum Exposure, Undiscounted

0.02

'

'

'

'

'

'

'

'

0.02

'

'

'

'

'

'

'

'

'

'

Variable Interest Entity, Measure of Activity, Expense

'

'

'

'

'

'

'

'

'

$39,000,000

$28,000,000

'

'

'

'

'

'

'

'

'

Derivative_and_Other_Hedging_I3

Derivative and Other Hedging Instruments (Summary Of Outstanding Interest Rate Swaps) (Details) (USD $)

3 Months Ended

12 Months Ended

12 Months Ended

3 Months Ended

In Millions, unless otherwise specified

Dec. 31, 2013

Sep. 30, 2013

Jun. 30, 2013

Mar. 31, 2013

Dec. 31, 2012

Sep. 30, 2012

Jun. 30, 2012

Mar. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2011

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2013

Interest Rate Swap [Member]

Interest Rate Swap [Member]

Discontinuation of Election to Account for Interest Rate Swaps as Designated Cash Flow Hedges [Member]

Discontinuation of Election to Account for Interest Rate Swaps as Designated Cash Flow Hedges [Member]

Discontinuation of Election to Account for Interest Rate Swaps as Designated Cash Flow Hedges [Member]

Interest Rate Swap [Member]

Interest Rate Swaps Excluding Forward Starting [Member]

Interest Rate Swap [Member]

Interest Rate Swap [Member]

Derivative, Notional Amount

$2,119

'

'

'

$12,477

'

'

'

$2,119

$12,477

'

'

'

'

'

'

$4,000

'

Derivative, Higher Remaining Maturity Range

'

'

'

'

'

'

'

'

'1 year 10 months 14 days

'

'

'

'

'

'

'

'

'

Derivative, Average Fixed Interest Rate

'

'

'

'

'

'

'

'

'

'

'

1.70%

1.46%

'

'

'

'

1.57%

Derivative Instruments, Gain Reclassified from Accumulated OCI into Income, Effective Portion

'

'

'

'

'

'

'

'

424

252

35

'

'

'

'

'

'

'

Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax

$46

$47

$48

$49

$50

$51

$52

$52

$189

$205

($650)

'

'

$189

$194

$54

'

'

Derivative_and_Other_Hedging_I4

Derivative and Other Hedging Instruments (Remaining Interest Rate Swap Term) (Details) (USD $)	3 Months Ended								12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Unrealized (loss) gain on derivative instruments, net	$46	$47	$48	$49	$50	$51	$52	$52	$189	$205	($650)
Derivative, Notional Amount	2,119	'	'	'	12,477	'	'	'	2,119	12,477	'
Remaining interest rate swap term, maximum	'	'	'	'	'	'	'	'	'1 year 10 months 14 days	'	'
Interest Rate Swap [Member]	'	'	'	'	'	'	'	'	'	'	'
Notional Amount	43,250	'	'	'	46,850	'	'	'	43,250	46,850	'
Derivative, Average Remaining Maturity	'	'	'	'	'	'	'	'	'4 years 8 months	'4 years 5 months 0 days	'
Average Fixed Pay Rate	1.70%	'	'	'	1.46%	'	'	'	1.70%	1.46%	'
Average Receive Rate	0.22%	'	'	'	0.29%	'	'	'	0.22%	0.29%	'
Net Estimated Fair Value	480	'	'	'	-1,229	'	'	'	480	-1,229	'
Interest Rate Swap [Member]	'	'	'	'	'	'	'	'	'	'	'
Derivative, Notional Amount	$4,000	'	'	'	'	'	'	'	$4,000	'	'

Derivative_and_Other_Hedging_I5

Derivative and Other Hedging Instruments (Summary Of Outstanding Interest Rate Swaps Designated As Hedging Instruments) (Details) (USD $)

3 Months Ended

12 Months Ended

12 Months Ended

3 Months Ended

In Millions, unless otherwise specified

Dec. 31, 2013

Sep. 30, 2013

Jun. 30, 2013

Mar. 31, 2013

Dec. 31, 2012

Sep. 30, 2012

Jun. 30, 2012

Mar. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2012

Dec. 31, 2011

Forward Contracts [Member]

Discontinuation of Election to Account for Interest Rate Swaps as Designated Cash Flow Hedges [Member]

Discontinuation of Election to Account for Interest Rate Swaps as Designated Cash Flow Hedges [Member]

Interest Rate Swap [Member]

Interest Rate Swap [Member]

Interest Rate Swap [Member]

Interest Rate Swap [Member]

Forward Contracts [Member]

Discontinuation of Election to Account for Interest Rate Swaps as Designated Cash Flow Hedges [Member]

Derivative [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Derivative, Notional Amount

$2,119

'

'

'

$12,477

'

'

'

$2,119

$12,477

'

$150

[1]

'

'

'

'

$1,700

'

Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax

46

47

48

49

50

51

52

52

189

205

-650

'

189

194

'

'

'

54

Notional Amount

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$43,250

$46,850

'

'

[1]

2.Cost basis represents the forward price to be paid/(received) for the underlying agency security.

Derivative_and_Other_Hedging_I6

Derivative and Other Hedging Instruments (Effect Of Interest Rate Swaps Designated As Hedges) (Details) (USD $)

3 Months Ended

12 Months Ended

In Millions, unless otherwise specified

Dec. 31, 2013

Sep. 30, 2013

Jun. 30, 2013

Mar. 31, 2013

Dec. 31, 2012

Sep. 30, 2012

Jun. 30, 2012

Mar. 31, 2012

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Derivatives, Fair Value [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax

$46

$47

$48

$49

$50

$51

$52

$52

'

$189

$205

($650)

Net Periodic Interest Rate Costs on Swaps

'

'

'

'

'

'

'

'

89

613

457

'

Amount of Gain or (Loss) Recognized in OCI (Effective Portion)

'

'

'

'

'

'

'

'

'

'

'

-707

Amount of Gain or (Loss) Reclassified from OCI into Earnings (Effective Portion)

'

'

'

'

'

'

'

'

'

'

'

-140

Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing, Net

'

'

'

'

'

'

'

'

'

'

'

-2

Derivative Instruments, Gain Reclassified from Accumulated OCI into Income, Effective Portion

'

'

'

'

'

'

'

'

'

424

252

35

Discontinuation of Election to Account for Interest Rate Swaps as Designated Cash Flow Hedges [Member]

'

'

'

'

'

'

'

'

'

'

'

'

Derivatives, Fair Value [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax

'

'

'

'

'

'

'

'

'

189

'

194

Discontinuation of Election to Account for Interest Rate Swaps as Designated Cash Flow Hedges [Member] | Interest Rate Swap [Member]

'

'

'

'

'

'

'

'

'

'

'

'

Derivatives, Fair Value [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax

'

'

'

'

'

'

'

'

$54

'

'

'

Derivative_and_Other_Hedging_I7

Derivative and Other Hedging Instruments (Summary Of Outstanding Forward Contracts Designated As Hedging Instruments) (Details) (USD $)	3 Months Ended	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2011	Dec. 31, 2011	Dec. 31, 2010
					Interest Rate Swap [Member]	Interest Rate Swap [Member]	Hedge De-Designations [Member]	Notional Terminations/Expirations During the Period [Member] [Member]	Notional Additions During the Period [Member]	Designated as Hedging Instrument [Member]
							Interest Rate Swap [Member]	Interest Rate Swap [Member]	Interest Rate Swap [Member]	Interest Rate Swap [Member]
Net Periodic Interest Rate Costs on Swaps	$89	$613	$457	'	'	'	'	'	'	'
Notional Amount	'	'	'	'	43,250	46,850	-23,900	-450	17,900	6,450
Derivative Instruments, Gain Reclassified from Accumulated OCI into Income, Effective Portion	'	$424	$252	$35	'	'	'	'	'	'

Derivative_and_Other_Hedging_I8

Derivative and Other Hedging Instruments (Effect of Forward Contracts Designated as Hedges) (Details) (USD $)	3 Months Ended								12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Amount of Gain or (Loss) Recognized in OCI (Effective Portion)	'	'	'	'	'	'	'	'	'	'	($707)
Amount of Gain or (Loss) Reclassified from OCI into Earnings (Effective Portion)	'	'	'	'	'	'	'	'	'	'	-140
Amount of Gain or (Loss) Recognized in Earnings (Ineffective Portion and Amount Excluded from Effectiveness Testing)	'	'	'	'	'	'	'	'	'	'	-2
Unrealized (loss) gain on derivative instruments, net	$46	$47	$48	$49	$50	$51	$52	$52	$189	$205	($650)

Derivative_and_Other_Hedging_I9

Derivative and Other Hedging Instruments (Summary of Long and Short Position of Derivative Instruments) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
Gain (loss) on REIT Equity Securities	$2		'		'
Variable Interest Entity, Measure of Activity, Expense	39		28		'
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	1,156		-1,342		-428
Derivative Instruments Not Designated as Hedging Instruments, Asset, at Fair Value	1,194		301		'
Derivative Instruments Not Designated as Hedging Instruments, Liability, at Fair Value	422		1,264		'
Loss on Interest Only Securities Remeasured at Fair Value Through Earnings	0		'		-17
Derivative Asset, Fair Value, Gross Asset	2,271		12,870		'
Fair Value of Derivative Instruments	-5		95		'
Interest Rate Swap [Member]	'		'		'
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	1,145		-1,034		-119
Derivative Instruments Not Designated as Hedging Instruments, Asset, at Fair Value	'		14		'
Derivative Instruments Not Designated as Hedging Instruments, Liability, at Fair Value	400		1,243		'
Interest Rate Swaption [Member]	'		'		'
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	258		-106		-64
Derivative Instruments Not Designated as Hedging Instruments, Asset, at Fair Value	'		171		'
Purchases Of TBAs And Forward Settling Agency Securities [Member]	'		'		'
Derivative Instruments Not Designated as Hedging Instruments, Asset, at Fair Value	2		116		'
Derivative Instruments Not Designated as Hedging Instruments, Liability, at Fair Value	-20		-1		'
Sale Of TBA And Forward Settling Agency Securities [Member]	'		'		'
Derivative Instruments Not Designated as Hedging Instruments, Asset, at Fair Value	15		'		'
Derivative Instruments Not Designated as Hedging Instruments, Liability, at Fair Value	2		20		'
TBA securities Fifteen Year and Thirty Year Securities [Member]	'		'		'
Derivative, Forward Settlement Value	2,276		12,612		'
Derivative Asset, Fair Value, Gross Asset	2,271		12,708		'
Fair Value of Derivative Instruments	-5	[1]	96	[1]	'
TBA securities Fifteen Year and Thirty Year Securities [Member] | Long [Member]	'		'		'
Derivative, Forward Settlement Value	6,882		22,603		'
Derivative Asset, Fair Value, Gross Asset	6,864		22,719		'
Fair Value of Derivative Instruments	-18		116		'
TBA securities Fifteen Year and Thirty Year Securities [Member] | Short [Member]	'		'		'
Derivative, Forward Settlement Value	-4,606		-9,991		'
Derivative Liability, Fair Value, Gross Liability	-4,593		-10,011		'
Fair Value of Derivative Instruments	13		-20		'
Forward Contracts [Member]	'		'		'
Derivative, Forward Settlement Value	'		163		'
Derivative Asset, Fair Value, Gross Asset	'		162		'
Fair Value of Derivative Instruments	'		-1	[2]	'
Forward Contracts [Member] | Long [Member]	'		'		'
Derivative, Forward Settlement Value	'		163		'
Derivative Asset, Fair Value, Gross Asset	'		162		'
Fair Value of Derivative Instruments	'		-1		'
Fair Value, Inputs, Level 2 [Member] | Interest Rate Swap [Member]	'		'		'
Derivative Instruments Not Designated as Hedging Instruments, Asset, at Fair Value	880		14		'
Fair Value, Inputs, Level 2 [Member] | Interest Rate Swaption [Member]	'		'		'
Derivative Instruments Not Designated as Hedging Instruments, Asset, at Fair Value	258		171		'
Fair Value, Inputs, Level 1 [Member] | US Treasury Securities [Member] | Future [Member]	'		'		'
Derivative Instruments Not Designated as Hedging Instruments, Liability, at Fair Value	-39		'		'
Other Derivatives [Member]	'		'		'
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	($6)		'		'
[1]	1.Notional amount represents the par value (or principal balance) of the underlying agency security.
[2]	2.Cost basis represents the forward price to be paid/(received) for the underlying agency security.

Recovered_Sheet2

Derivative and Other Hedging Instruments (Summary Of Outstanding Interest Rate Swaps Agreements Not Designated As Hedges) (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Obligation to Return Securities Borrowed Under Reverse Repurchase Agreements at Fair Value	$1,848,000,000	$11,763,000,000	'	'
Derivative Instruments Not Designated as Hedging Instruments, Asset, at Fair Value	1,194,000,000	301,000,000	'	'
Derivative Instruments Not Designated as Hedging Instruments, Liability, at Fair Value	-422,000,000	-1,264,000,000	'	'
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	1,156,000,000	-1,342,000,000	-428,000,000	'
Proceeds from Securities Purchased under Agreements to Resell	1,900,000,000	11,700,000,000	'	'
Interest Rate Swap [Member]	'	'	'	'
Derivative Instruments Not Designated as Hedging Instruments, Asset, at Fair Value	'	14,000,000	'	'
Notional Amount	43,250,000,000	46,850,000,000	'	'
Net Estimated Fair Value	480,000,000	-1,229,000,000	'	'
Derivative Instruments Not Designated as Hedging Instruments, Liability, at Fair Value	-400,000,000	-1,243,000,000	'	'
Notional Amount Of Derivatives Not Designated As Hedging Instruments Additions During The Period	-20,750,000,000	-25,000,000,000	-6,750,000,000	'
Notional Amount Of Derivatives Not Designated As Hedging Instruments additions due to Hedge De-Designations	'	'	-23,900,000,000	'
Notional Amount Of Derivatives Not Designated As Hedging Instruments Settlement Expiration During The Period	24,350,000,000	8,400,000,000	450,000,000	'
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	1,145,000,000	-1,034,000,000	-119,000,000	'
Term (Years)	'4 years 8 months	'4 years 5 months 0 days	'	'
Derivative, Average Fixed Interest Rate	1.70%	1.46%	'	'
Derivative, Average Variable Interest Rate	0.22%	0.29%	'	'
Interest Rate Swaption [Member]	'	'	'	'
Derivative Instruments Not Designated as Hedging Instruments, Asset, at Fair Value	'	171,000,000	'	'
Notional Amount	14,250,000,000	14,450,000,000	'	'
Notional Amount Of Derivatives Not Designated As Hedging Instruments Additions During The Period	-23,800,000,000	-18,250,000,000	-5,350,000,000	'
Notional Amount Of Derivatives Not Designated As Hedging Instruments Settlement Expiration During The Period	24,000,000,000	7,000,000,000	3,000,000,000	'
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	258,000,000	-106,000,000	-64,000,000	'
Term (Years)	'7 years	'7 years 9 months 12 days	'	'
Derivative, Average Fixed Interest Rate	3.09%	2.99%	'	'
TBA and Forward Settling Agency Securities [Member]	'	'	'	'
Notional Amount	2,119,000,000	12,477,000,000	-104,000,000	-849,000,000
Notional Amount Of Derivatives Not Designated As Hedging Instruments Additions During The Period	42,707,000,000	-36,174,000,000	-48,589,000,000	'
Notional Amount Of Derivatives Not Designated As Hedging Instruments Settlement Expiration During The Period	'	48,755,000,000	49,334,000,000	'
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	-726,000,000	31,000,000	-142,000,000	'
Sale Of TBA And Forward Settling Agency Securities [Member]	'	'	'	'
Derivative Instruments Not Designated as Hedging Instruments, Asset, at Fair Value	15,000,000	'	'	'
Derivative Instruments Not Designated as Hedging Instruments, Liability, at Fair Value	-2,000,000	-20,000,000	'	'
Put Option [Member]	'	'	'	'
Notional Amount Of Derivatives Not Designated As Hedging Instruments Additions During The Period	-50,000,000	'	-200,000,000	'
Notional Amount Of Derivatives Not Designated As Hedging Instruments Settlement Expiration During The Period	50,000,000	'	200,000,000	'
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	'	'	1,000,000	'
Greater Than One Year and Less Than or Equal to Three Years [Member] | Interest Rate Swap [Member]	'	'	'	'
Notional Amount	16,750,000,000	14,600,000,000	'	'
Net Estimated Fair Value	-382,000,000	-294,000,000	'	'
Term (Years)	'1 year 7 months	'2 years 0 months 0 days	'	'
Derivative, Average Fixed Interest Rate	1.57%	1.23%	'	'
Derivative, Average Variable Interest Rate	0.19%	0.26%	'	'
Greater Than One Year and Less Than or Equal to Three Years [Member] | Interest Rate Swaption [Member]	'	'	'	'
Notional Amount	3,600,000,000	4,050,000,000	'	'
Term (Years)	'5 years 7 months	'6 years 8 months	'	'
Derivative, Average Fixed Interest Rate	3.40%	2.82%	'	'
Greater Than Three Years and Less Than or Equal to Five Years [Member] | Interest Rate Swap [Member]	'	'	'	'
Notional Amount	10,225,000,000	20,250,000,000	'	'
Net Estimated Fair Value	81,000,000	-666,000,000	'	'
Term (Years)	'3 years 11 months	'4 years 1 month 0 days	'	'
Derivative, Average Fixed Interest Rate	1.07%	1.48%	'	'
Derivative, Average Variable Interest Rate	0.24%	0.29%	'	'
Greater Than Five Years and Less than or Equal to Seven Years [Member] | Interest Rate Swap [Member]	'	'	'	'
Notional Amount	5,700,000,000	5,600,000,000	'	'
Net Estimated Fair Value	113,000,000	-163,000,000	'	'
Term (Years)	'6 years	'6 years 1 month 0 days	'	'
Derivative, Average Fixed Interest Rate	1.97%	1.53%	'	'
Derivative, Average Variable Interest Rate	0.26%	0.34%	'	'
Greater Than Seven Years and Less than or Equal to Ten Years [Member] | Interest Rate Swap [Member]	'	'	'	'
Notional Amount	8,825,000,000	5,200,000,000	'	'
Net Estimated Fair Value	499,000,000	-113,000,000	'	'
Term (Years)	'8 years 9 months	'9 years 2 months 0 days	'	'
Derivative, Average Fixed Interest Rate	2.28%	1.89%	'	'
Derivative, Average Variable Interest Rate	0.24%	0.35%	'	'
Greater Than Ten Years [Member] | Interest Rate Swap [Member]	'	'	'	'
Notional Amount	1,750,000,000	1,200,000,000	'	'
Net Estimated Fair Value	169,000,000	7,000,000	'	'
Term (Years)	'14 years 8 months	'10 years 2 months 0 days	'	'
Derivative, Average Fixed Interest Rate	2.79%	1.79%	'	'
Derivative, Average Variable Interest Rate	0.24%	0.31%	'	'
Not Designated as Hedging Instrument [Member] | Interest Rate Swap [Member]	'	'	'	'
Notional Amount	-43,250,000,000	-46,850,000,000	-30,250,000,000	-50,000,000
Not Designated as Hedging Instrument [Member] | Interest Rate Swaption [Member]	'	'	'	'
Notional Amount	-14,250,000,000	-14,450,000,000	-3,200,000,000	-850,000,000
Short [Member] | Total Return Swap [Member]	'	'	'	'
Notional Amount	'	'	-165,000,000	'
Notional Amount Of Derivatives Not Designated As Hedging Instruments Additions During The Period	'	'	510,000,000	'
Notional Amount Of Derivatives Not Designated As Hedging Instruments Settlement Expiration During The Period	'	165,000,000	-675,000,000	'
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	'	'	7,000,000	'
Short [Member] | US Treasury Securities [Member]	'	'	'	'
Notional Amount	-2,007,000,000	-11,835,000,000	-880,000,000	-250,000,000
Notional Amount Of Derivatives Not Designated As Hedging Instruments Additions During The Period	-31,941,000,000	-36,555,000,000	-15,794,000,000	'
Notional Amount Of Derivatives Not Designated As Hedging Instruments Settlement Expiration During The Period	41,769,000,000	25,600,000,000	15,164,000,000	'
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	472,000,000	-142,000,000	-133,000,000	'
Long [Member] | US Treasury Securities [Member]	'	'	'	'
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	-42,000,000	-1,000,000	34,000,000	'
Trading Securities Added During the Period	27,805,000,000	2,445,000,000	5,140,000,000	'
Notional Amount Of Trading Securities Settlement Expiration During The Period	-23,878,000,000	-2,545,000,000	-5,040,000,000	'
Trading Securities	3,927,000,000	'	100,000,000	'
Future [Member] | US Treasury Securities [Member]	'	'	'	'
Notional Amount	-1,880,000,000	'	-783,000,000	'
Notional Amount Of Derivatives Not Designated As Hedging Instruments Additions During The Period	-9,239,000,000	-3,838,000,000	-1,083,000,000	'
Notional Amount Of Derivatives Not Designated As Hedging Instruments Settlement Expiration During The Period	7,359,000,000	4,621,000,000	300,000,000	'
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	$49,000,000	($90,000,000)	($12,000,000)	'

Recovered_Sheet3

Derivative and Other Hedging Instruments (Summary Of Outstanding Interest Rate Swaps Agreements Designated As Hedges in the Future) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Payer Swaption [Member]	'	'
Interest Rate Derivative Not Designated As Hedging Instruments Receive Rate	'3M	'1M / 3M
Interest Rate Swaption [Member]	'	'
Cost	335	274
Fair Value	258	171
Cash Flow Hedges Derivative Instruments Not Designated As Hedging Instruments Average Months To Expiration	10	21
Notional Amount	14,250	14,450
Average Fixed Pay Rate	3.09%	2.99%
Term (Years)	'7 years	'7 years 9 months 12 days
Discontinuation of Election to Account for Interest Rate Swaps as Designated Cash Flow Hedges [Member] | Interest Rate Swaps [Member]	'	'
Term (Years)	'2 years 1 month 20 days	'
Less Than or Equal to One Year [Member] | Payer Swaption [Member]	'	'
Interest Rate Derivative Not Designated As Hedging Instruments Receive Rate	'3M	'1M / 3M
Less Than or Equal to One Year [Member] | Interest Rate Swaption [Member]	'	'
Cost	193	76
Fair Value	117	15
Cash Flow Hedges Derivative Instruments Not Designated As Hedging Instruments Average Months To Expiration	4	4
Notional Amount	9,400	5,150
Average Fixed Pay Rate	2.87%	2.65%
Term (Years)	'7 years 9 months	'8 years 6 months 24 days
Greater Than One Year and Less Than or Equal to Three Years [Member] | Payer Swaption [Member]	'	'
Interest Rate Derivative Not Designated As Hedging Instruments Receive Rate	'3M	'3M
Greater Than One Year and Less Than or Equal to Three Years [Member] | Interest Rate Swaption [Member]	'	'
Cost	105	65
Fair Value	92	34
Cash Flow Hedges Derivative Instruments Not Designated As Hedging Instruments Average Months To Expiration	19	19
Notional Amount	3,600	4,050
Average Fixed Pay Rate	3.40%	2.82%
Term (Years)	'5 years 7 months	'6 years 8 months
greater than two years less than or equal to three years [Member] | Payer Swaption [Member]	'	'
Interest Rate Derivative Not Designated As Hedging Instruments Receive Rate	'3M	'3M
greater than two years less than or equal to three years [Member] | Interest Rate Swaption [Member]	'	'
Cost	35	97
Fair Value	45	87
Cash Flow Hedges Derivative Instruments Not Designated As Hedging Instruments Average Months To Expiration	30	33
Notional Amount	1,150	3,900
Average Fixed Pay Rate	3.81%	3.51%
Term (Years)	'5 years 9 months	'8 years 6 months 24 days
greater than three years less than or equal to four years [Member] | Payer Swaption [Member]	'	'
Interest Rate Derivative Not Designated As Hedging Instruments Receive Rate	'	'3M
greater than three years less than or equal to four years [Member] | Interest Rate Swaption [Member]	'	'
Cost	'	12
Fair Value	'	11
Cash Flow Hedges Derivative Instruments Not Designated As Hedging Instruments Average Months To Expiration	'	46
Notional Amount	'	450
Average Fixed Pay Rate	'	3.20%
Term (Years)	'	'6 years 1 month 12 days
greater than four years less than or equal to five years [Member] | Payer Swaption [Member]	'	'
Interest Rate Derivative Not Designated As Hedging Instruments Receive Rate	'3M	'3M
greater than four years less than or equal to five years [Member] | Interest Rate Swaption [Member]	'	'
Cost	2	24
Fair Value	4	24
Cash Flow Hedges Derivative Instruments Not Designated As Hedging Instruments Average Months To Expiration	52	59
Notional Amount	100	900
Average Fixed Pay Rate	4.80%	3.33%
Term (Years)	'7 years	'5 years 0 months

Recovered_Sheet4

Derivative and Other Hedging Instruments (Summary of Outstanding TBAs) (Details) (USD $)	Dec. 31, 2013		Dec. 31, 2012
In Millions, unless otherwise specified
Derivative [Line Items]	'		'
Derivative Asset, Fair Value, Gross Asset	$2,271		$12,870
Notional Amount	2,119		12,477
Secured Debt, Dollar Rolls	2,276		12,775
Fair Value of Derivative Instruments	-5		95
TBA securities Fifteen Year and Thirty Year Securities [Member]	'		'
Derivative [Line Items]	'		'
Derivative Asset, Fair Value, Gross Asset	2,271		12,708
Notional Amount	2,119	[1]	12,327	[1]
Derivative, Forward Settlement Value	2,276		12,612
Fair Value of Derivative Instruments	-5	[1]	96	[1]
Forward Contracts [Member]	'		'
Derivative [Line Items]	'		'
Derivative Asset, Fair Value, Gross Asset	'		162
Notional Amount	'		150	[2]
Derivative, Forward Settlement Value	'		163
Fair Value of Derivative Instruments	'		-1	[2]
Long [Member] | TBA securities Fifteen Year and Thirty Year Securities [Member]	'		'
Derivative [Line Items]	'		'
Derivative Asset, Fair Value, Gross Asset	6,864		22,719
Notional Amount	6,660		21,705
Derivative, Forward Settlement Value	6,882		22,603
Fair Value of Derivative Instruments	-18		116
Long [Member] | Forward Contracts [Member]	'		'
Derivative [Line Items]	'		'
Derivative Asset, Fair Value, Gross Asset	'		162
Notional Amount	'		150
Derivative, Forward Settlement Value	'		163
Fair Value of Derivative Instruments	'		-1
Short [Member] | TBA securities Fifteen Year and Thirty Year Securities [Member]	'		'
Derivative [Line Items]	'		'
Derivative Liability, Fair Value, Gross Liability	-4,593		-10,011
Notional Amount	-4,541		-9,378
Derivative, Forward Settlement Value	-4,606		-9,991
Fair Value of Derivative Instruments	$13		($20)
[1]	1.Notional amount represents the par value (or principal balance) of the underlying agency security.
[2]	2.Cost basis represents the forward price to be paid/(received) for the underlying agency security.

Recovered_Sheet5

Derivative and Other Hedging Instruments (Summary Of Derivatives Outstanding Not Designated As Hedging Instruments) (Details) (USD $)

3 Months Ended

12 Months Ended

12 Months Ended

12 Months Ended

3 Months Ended

12 Months Ended

12 Months Ended

12 Months Ended

Dec. 31, 2013

Sep. 30, 2013

Jun. 30, 2013

Mar. 31, 2013

Dec. 31, 2012

Sep. 30, 2012

Jun. 30, 2012

Mar. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2010

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2011

Dec. 31, 2012

Dec. 31, 2010

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2012

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2010

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2010

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2010

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Put Option [Member]

Put Option [Member]

Purchases Of TBAs And Forward Settling Agency Securities [Member]

Purchases Of TBAs And Forward Settling Agency Securities [Member]

Purchases Of TBAs And Forward Settling Agency Securities [Member]

Purchases Of TBAs And Forward Settling Agency Securities [Member]

Sale Of TBA And Forward Settling Agency Securities [Member]

Sale Of TBA And Forward Settling Agency Securities [Member]

Interest Rate Swap [Member]

Interest Rate Swap [Member]

Interest Rate Swap [Member]

Interest Rate Swaption [Member]

Interest Rate Swaption [Member]

Interest Rate Swaption [Member]

Payer Swaption [Member]

Payer Swaption [Member]

Purchases Of TBAs And Forward Settling Agency Securities [Member]

Purchases Of TBAs And Forward Settling Agency Securities [Member]

Discontinuation of Election to Account for Interest Rate Swaps as Designated Cash Flow Hedges [Member]

Discontinuation of Election to Account for Interest Rate Swaps as Designated Cash Flow Hedges [Member]

Discontinuation of Election to Account for Interest Rate Swaps as Designated Cash Flow Hedges [Member]

Discontinuation of Election to Account for Interest Rate Swaps as Designated Cash Flow Hedges [Member]

Discontinuation of Election to Account for Interest Rate Swaps as Designated Cash Flow Hedges [Member]

Less Than or Equal to One Year [Member]

Less Than or Equal to One Year [Member]

Less Than or Equal to One Year [Member]

Less Than or Equal to One Year [Member]

Greater Than One Year and Less Than or Equal to Three Years [Member]

Greater Than One Year and Less Than or Equal to Three Years [Member]

Greater Than One Year and Less Than or Equal to Three Years [Member]

Greater Than One Year and Less Than or Equal to Three Years [Member]

Greater Than One Year and Less Than or Equal to Three Years [Member]

Greater Than One Year and Less Than or Equal to Three Years [Member]

greater than two years less than or equal to three years [Member]

greater than two years less than or equal to three years [Member]

greater than two years less than or equal to three years [Member]

greater than two years less than or equal to three years [Member]

greater than three years less than or equal to four years [Member]

greater than three years less than or equal to four years [Member]

greater than four years less than or equal to five years [Member]

greater than four years less than or equal to five years [Member]

greater than four years less than or equal to five years [Member]

greater than four years less than or equal to five years [Member]

Not Designated as Hedging Instrument [Member]

Not Designated as Hedging Instrument [Member]

Not Designated as Hedging Instrument [Member]

Not Designated as Hedging Instrument [Member]

Not Designated as Hedging Instrument [Member]

Not Designated as Hedging Instrument [Member]

Not Designated as Hedging Instrument [Member]

Not Designated as Hedging Instrument [Member]

Forward Contracts [Member]

Short [Member]

Short [Member]

Short [Member]

Short [Member]

Long [Member]

Long [Member]

Long [Member]

Future [Member]

Future [Member]

Future [Member]

Interest Rate Swap [Member]

Interest Rate Swaption [Member]

Interest Rate Swaption [Member]

Payer Swaption [Member]

Payer Swaption [Member]

Interest Rate Swap [Member]

Interest Rate Swap [Member]

Interest Rate Swaption [Member]

Interest Rate Swaption [Member]

Payer Swaption [Member]

Payer Swaption [Member]

Interest Rate Swaption [Member]

Interest Rate Swaption [Member]

Payer Swaption [Member]

Payer Swaption [Member]

Interest Rate Swaption [Member]

Payer Swaption [Member]

Interest Rate Swaption [Member]

Interest Rate Swaption [Member]

Payer Swaption [Member]

Payer Swaption [Member]

Interest Rate Swap [Member]

Interest Rate Swap [Member]

Interest Rate Swap [Member]

Interest Rate Swap [Member]

Interest Rate Swaption [Member]

Interest Rate Swaption [Member]

Interest Rate Swaption [Member]

Interest Rate Swaption [Member]

Interest Rate Swap [Member]

US Treasury Securities [Member]

US Treasury Securities [Member]

US Treasury Securities [Member]

US Treasury Securities [Member]

US Treasury Securities [Member]

US Treasury Securities [Member]

US Treasury Securities [Member]

US Treasury Securities [Member]

US Treasury Securities [Member]

US Treasury Securities [Member]

Options At Cost

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$335,000,000

$274,000,000

'

'

'

'

'

'

'

'

'

'

$193,000,000

$76,000,000

'

'

'

'

$105,000,000

$65,000,000

'

'

$35,000,000

$97,000,000

'

'

$12,000,000

'

$2,000,000

$24,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Interest Rate Derivatives, at Fair Value, Net

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

258,000,000

171,000,000

'

'

'

'

'

'

'

'

'

'

117,000,000

15,000,000

'

'

'

'

92,000,000

34,000,000

'

'

45,000,000

87,000,000

'

'

11,000,000

'

4,000,000

24,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Cash Flow Hedges Derivative Instruments Not Designated As Hedging Instruments Average Months To Expiration

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

10

21

'

'

'

'

'

'

'

'

'

'

4

4

'

'

'

'

19

19

'

'

30

33

'

'

46

'

52

59

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Notional Amount

'

'

'

'

'

'

'

'

'

'

'

'

'

2,119,000,000

12,477,000,000

-104,000,000

-849,000,000

'

'

43,250,000,000

46,850,000,000

'

14,250,000,000

14,450,000,000

'

'

'

'

'

'

'

'

'

'

9,400,000,000

5,150,000,000

'

'

16,750,000,000

14,600,000,000

3,600,000,000

4,050,000,000

'

'

1,150,000,000

3,900,000,000

'

'

450,000,000

'

100,000,000

900,000,000

'

'

-43,250,000,000

-46,850,000,000

-30,250,000,000

-50,000,000

-14,250,000,000

-14,450,000,000

-3,200,000,000

-850,000,000

'

-2,007,000,000

-11,835,000,000

-880,000,000

-250,000,000

'

'

'

-1,880,000,000

'

-783,000,000

Derivative, Average Fixed Interest Rate

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

1.70%

1.46%

'

3.09%

2.99%

'

'

'

'

'

'

'

'

'

'

2.87%

2.65%

'

'

1.57%

1.23%

3.40%

2.82%

'

'

3.81%

3.51%

'

'

3.20%

'

4.80%

3.33%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Interest Rate Derivative Not Designated As Hedging Instruments Receive Rate

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'3M

'1M / 3M

'

'

'

'

'

'

'

'

'

'3M

'1M / 3M

'

'

'

'

'3M

'3M

'

'

'3M

'3M

'

'3M

'

'

'3M

'3M

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Gain On Interest Only Securities Remeasured at Fair Value Through Earnings

'

'

'

'

'

'

'

'

'

17,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net

'

'

'

'

'

'

'

'

1,156,000,000

-1,342,000,000

-428,000,000

'

1,000,000

-726,000,000

31,000,000

-142,000,000

'

'

'

1,145,000,000

-1,034,000,000

-119,000,000

258,000,000

-106,000,000

-64,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

472,000,000

-142,000,000

-133,000,000

'

-42,000,000

-1,000,000

34,000,000

49,000,000

-90,000,000

-12,000,000

Trading Securities

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

3,927,000,000

'

100,000,000

'

'

'

Trading Securities Added During the Period

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

27,805,000,000

2,445,000,000

5,140,000,000

'

'

'

Notional Amount Of Trading Securities Settlement Expiration During The Period

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

-23,878,000,000

-2,545,000,000

-5,040,000,000

'

'

'

Notional Amount Of Derivatives Not Designated As Hedging Instruments Settlement Expiration During The Period

'

'

'

'

'

'

'

'

'

'

'

50,000,000

200,000,000

'

48,755,000,000

49,334,000,000

'

'

'

24,350,000,000

8,400,000,000

450,000,000

24,000,000,000

7,000,000,000

3,000,000,000

'

'

-53,065,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

41,769,000,000

25,600,000,000

15,164,000,000

'

'

'

'

7,359,000,000

4,621,000,000

300,000,000

Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax

46,000,000

47,000,000

48,000,000

49,000,000

50,000,000

51,000,000

52,000,000

52,000,000

189,000,000

205,000,000

-650,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

189,000,000

194,000,000

'

'

54,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net

'

'

'

'

'

'

'

'

'

'

-140,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Derivative assets not designated as hedging instruments

1,194,000,000

'

'

'

301,000,000

'

'

'

1,194,000,000

301,000,000

'

'

'

'

'

'

'

15,000,000

'

'

14,000,000

'

'

171,000,000

'

'

'

2,000,000

116,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Derivative liabilities not designated as hedging instruments

-422,000,000

'

'

'

-1,264,000,000

'

'

'

-422,000,000

-1,264,000,000

'

'

'

'

'

'

'

-2,000,000

-20,000,000

-400,000,000

-1,243,000,000

'

'

'

'

'

'

20,000,000

1,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Deferred Gain (Loss) on Discontinuation of Interest Rate Fair Value Hedge

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

296,000,000

690,000,000

485,000,000

40,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Term (Years)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'4 years 8 months

'4 years 5 months 0 days

'

'7 years

'7 years 9 months 12 days

'

'

'

'

'

'

'

'

'

'

'7 years 9 months

'8 years 6 months 24 days

'

'

'1 year 7 months

'2 years 0 months 0 days

'5 years 7 months

'6 years 8 months

'

'

'5 years 9 months

'8 years 6 months 24 days

'

'

'6 years 1 month 12 days

'

'7 years

'5 years 0 months

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Deferred gain loss discontinued interest rate swap expected to be reclassified from OCI to interest expense next twelve months

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

156,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Derivative, Higher Remaining Maturity Range

'

'

'

'

'

'

'

'

'1 year 10 months 14 days

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'4 months

'

'

'

'

'

'

'

'

'

'

Notional Amount Of Derivatives Not Designated As Hedging Instruments Additions During The Period

'

'

'

'

'

'

'

'

'

'

'

-50,000,000

-200,000,000

42,707,000,000

-36,174,000,000

-48,589,000,000

'

'

'

-20,750,000,000

-25,000,000,000

-6,750,000,000

-23,800,000,000

-18,250,000,000

-5,350,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

-31,941,000,000

-36,555,000,000

-15,794,000,000

'

'

'

'

-9,239,000,000

-3,838,000,000

-1,083,000,000

Additions Due to Hedge De-Designations

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

-23,900,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Loss on Interest Only Securities Remeasured at Fair Value Through Earnings

'

'

'

'

'

'

'

'

0

'

-17,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Derivative, Net Hedge Ineffectiveness Gain (Loss)

'

'

'

'

'

'

'

'

'

'

-2,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Credit Derivative, Maximum Exposure, Undiscounted

$0.02

'

'

'

'

'

'

'

$0.02

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Recovered_Sheet6

Derivative and Other Hedging Instruments (Effect Of Derivative Instruments Not Designated As Hedges On Income Statement) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Loss on Interest Only Securities Remeasured at Fair Value Through Earnings	$0	'	($17)
Amount Gain/(Loss) Recognized in Income on Derivatives	1,156	-1,342	-428
Derivative, Net Hedge Ineffectiveness Gain (Loss)	'	'	-2
Interest Only And Principal Only Strip [Member]	'	'	'
Unrealized Gain (Loss) on Securities	'	$17	$16

Offsetting_Assets_and_Liabilit2

Offsetting Assets and Liabilities (Details) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Millions, unless otherwise specified
Offsetting Assets and Liabilities [Line Items]	'	'
Gross Amounts of Cash Collateral Not Offset on the Balance Sheet	($610)	'
Liability [Member]	'	'
Offsetting Assets and Liabilities [Line Items]	'	'
Gross Amount of Recognized Assets (Liabilities)	63,933	75,721
Net Amount of Assets (Liabilities) Presented on the Balance Sheet	63,933	75,721
Gross Amounts of Financial Instruments Not Offset on the Balance Sheet	-2,212	-10,667
Gross Amounts of Cash Collateral Not Offset on the Balance Sheet	-61,721	-65,054
Liability [Member] | Swaption [Member] | Interest Rate Swap [Member]	'	'
Offsetting Assets and Liabilities [Line Items]	'	'
Gross Amount of Recognized Assets (Liabilities)	400	1,243
Net Amount of Assets (Liabilities) Presented on the Balance Sheet	400	1,243
Gross Amounts of Financial Instruments Not Offset on the Balance Sheet	-331	-185
Gross Amounts of Cash Collateral Not Offset on the Balance Sheet	-69	-1,058
Assets [Member]	'	'
Offsetting Assets and Liabilities [Line Items]	'	'
Gross Amount of Recognized Assets (Liabilities)	3,019	12,003
Net Amount of Assets (Liabilities) Presented on the Balance Sheet	3,019	12,003
Gross Amounts of Financial Instruments Not Offset on the Balance Sheet	-2,212	-10,667
Gross Amounts of Cash Collateral Not Offset on the Balance Sheet	'	-1,157
Net Amount After Deducting Gross Amounts Not Offset on the Balance Sheet From Net Amount of Assets (Liabilities) Presented on the Balance Sheet	197	179
Assets [Member] | Swaption [Member] | Interest Rate Swap [Member]	'	'
Offsetting Assets and Liabilities [Line Items]	'	'
Gross Amount of Recognized Assets (Liabilities)	1,138	185
Net Amount of Assets (Liabilities) Presented on the Balance Sheet	1,138	185
Gross Amounts of Financial Instruments Not Offset on the Balance Sheet	-331	-185
Gross Amounts of Cash Collateral Not Offset on the Balance Sheet	-610	'
Net Amount After Deducting Gross Amounts Not Offset on the Balance Sheet From Net Amount of Assets (Liabilities) Presented on the Balance Sheet	197	'
Repurchase Agreements [Member] | Liability [Member]	'	'
Offsetting Assets and Liabilities [Line Items]	'	'
Gross Amount of Recognized Assets (Liabilities)	63,533	74,478
Net Amount of Assets (Liabilities) Presented on the Balance Sheet	63,533	74,478
Gross Amounts of Financial Instruments Not Offset on the Balance Sheet	-1,881	-10,482
Gross Amounts of Cash Collateral Not Offset on the Balance Sheet	-61,652	-63,996
Reverse Repurchase Agreements [Member] | Assets [Member]	'	'
Offsetting Assets and Liabilities [Line Items]	'	'
Gross Amount of Recognized Assets (Liabilities)	1,881	11,818
Net Amount of Assets (Liabilities) Presented on the Balance Sheet	1,881	11,818
Gross Amounts of Financial Instruments Not Offset on the Balance Sheet	-1,881	-10,482
Gross Amounts of Cash Collateral Not Offset on the Balance Sheet	'	-1,157
Net Amount After Deducting Gross Amounts Not Offset on the Balance Sheet From Net Amount of Assets (Liabilities) Presented on the Balance Sheet	$0	$179

Fair_Value_Measurements_Detail

Fair Value Measurements (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Financial Instruments, Owned, Mortgages, Mortgage-backed and Asset-backed Securities, at Fair Value	$64,482	$83,710
Financial Instruments, Owned, US Government and Agency Obligations, at Fair Value	3,822	0
Derivative Assets	1,194	301
Other Long-term Debt	910	937
Obligation to return securities borrowed under reverse repurchase agreements, at fair value	-1,848	-11,763
Derivative Instruments Not Designated as Hedging Instruments, Asset, at Fair Value	1,194	301
Marketable Securities, Equity Securities	237	0
Derivative Instruments Not Designated as Hedging Instruments, Liability, at Fair Value	422	1,264
Derivative Liabilities	422	1,264
Transfers between hierarchy levels	'0	'
Fair Value, Inputs, Level 1 [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Obligation to return securities borrowed under reverse repurchase agreements, at fair value	'	-11,763
Fair Value, Inputs, Level 2 [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Other Long-term Debt	'	937
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Assets, Fair Value Disclosure	4,098	0
Liabilities, Fair Value Disclosure	1,848	11,763
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Assets, Fair Value Disclosure	67,096	85,546
Liabilities, Fair Value Disclosure	1,332	2,201
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | TBA and Forward Settling Agency Securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Derivative Assets	17	116
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Sale Of TBA And Forward Settling Agency Securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Derivative Assets	22	21
Interest Rate Swaption [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Derivative Instruments Not Designated as Hedging Instruments, Asset, at Fair Value	'	171
Interest Rate Swaption [Member] | Fair Value, Inputs, Level 2 [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Derivative Instruments Not Designated as Hedging Instruments, Asset, at Fair Value	258	171
Interest Rate Swap [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Derivative Instruments Not Designated as Hedging Instruments, Asset, at Fair Value	'	14
Derivative Instruments Not Designated as Hedging Instruments, Liability, at Fair Value	400	1,243
Interest Rate Swap [Member] | Fair Value, Inputs, Level 2 [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Derivative Instruments Not Designated as Hedging Instruments, Asset, at Fair Value	880	14
Interest Rate Swap [Member] | Derivative liabilities, at fair value [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Interest Rate Swap [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Derivative Instruments Not Designated as Hedging Instruments, Asset, at Fair Value	400	1,243
Collateralized Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 2 [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Financial Instruments, Owned, Mortgages, Mortgage-backed and Asset-backed Securities, at Fair Value	$65,941	$85,245

Management_Agreement_and_Relat1

Management Agreement and Related Party Transactions (Details) (USD $)	3 Months Ended								12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Related Party Transaction [Line Items]	'	'	'	'	'	'	'	'	'	'	'
Management Fee Expense	$31	$35	$37	$33	$31	$32	$28	$22	$136	$113	$55
Related Party Transaction, Expenses from Transactions with Related Party	'	'	'	'	'	'	'	'	10	9	7
Accounts Payable, Related Parties, Current	$13	'	'	'	$1	'	'	'	$13	$1	'

Income_Taxes_Details

Income Taxes (Details) (USD $)	12 Months Ended
In Millions, except Per Share data, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Investments, Owned, Federal Income Tax Note [Line Items]	'	'	'
Preferred Stock, Dividend Rate, Per-Dollar-Amount	$2	$1.06	'
Dividends, Preferred Stock	$14	$7	'
Undistributed Taxable Income	210	'	'
Excise and Sales Taxes	3	25	2
Income Tax Expense (Benefit)	10	-6	4
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	39.50%	'	'
Common Stock, Dividends, Per Share, Cash Paid	$3.75	$5	$5.60
Dividends, Common Stock	1,453	1,518	886
Dividends, Common Stock, Cash	($1,453)	($1,518)	($886)
Qualified Dividends Per Share [Member]	'	'	'
Investments, Owned, Federal Income Tax Note [Line Items]	'	'	'
Preferred Stock, Dividend Rate, Per-Dollar-Amount	$0.02	'	'
Common Stock, Dividends, Per Share, Cash Paid	$0.03	'	'
Ordinary Income Per Share [Member]	'	'	'
Investments, Owned, Federal Income Tax Note [Line Items]	'	'	'
Preferred Stock, Dividend Rate, Per-Dollar-Amount	$2	$0.95	'
Common Stock, Dividends, Per Share, Cash Paid	$3.75	$4.51	$5.33
Long term Capital Gain [Member]	'	'	'
Investments, Owned, Federal Income Tax Note [Line Items]	'	'	'
Preferred Stock, Dividend Rate, Per-Dollar-Amount	'	$0.10	'
Common Stock, Dividends, Per Share, Cash Paid	'	$0.49	$0.27

Stockholders_Equity_Summary_of

Stockholders' Equity (Summary of Follow-on Public Offerings of Common Stock) (Details) (USD $)

1 Months Ended

3 Months Ended

12 Months Ended

12 Months Ended

9 Months Ended

12 Months Ended

12 Months Ended

3 Months Ended

12 Months Ended

Jul. 31, 2012

Mar. 31, 2012

Nov. 30, 2011

Jun. 30, 2011

Jan. 31, 2011

Dec. 31, 2013

Sep. 30, 2013

Jun. 30, 2013

Mar. 31, 2013

Dec. 31, 2012

Sep. 30, 2012

Jun. 30, 2012

Mar. 31, 2012

Mar. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2010

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2013

Sep. 30, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2010

Dec. 31, 2013

Dec. 31, 2011

Dec. 31, 2012

Dec. 31, 2010

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Jun. 30, 2012

At the Market Offering Program [Member]

Common Stock [Member]

Common Stock [Member]

Common Stock [Member]

Dividend Reinvestment And Direct Stock Purchase Plan [Member]

Agency Securities [Member]

Agency Securities [Member]

Agency Securities [Member]

Agency Securities [Member]

Agency Securities [Member]

Discontinuation of Election to Account for Interest Rate Swaps as Designated Cash Flow Hedges [Member]

Discontinuation of Election to Account for Interest Rate Swaps as Designated Cash Flow Hedges [Member]

Discontinuation of Election to Account for Interest Rate Swaps as Designated Cash Flow Hedges [Member]

Discontinuation of Election to Account for Interest Rate Swaps as Designated Cash Flow Hedges [Member]

Interest Rate Swap [Member]

Each Director [Member]

Each Director [Member]

Each Director [Member]

Director [Member]

Director [Member]

Director [Member]

Preferred Stock [Member]

Discontinuation of Election to Account for Interest Rate Swaps as Designated Cash Flow Hedges [Member]

Restricted Stock [Member]

Restricted Stock [Member]

Restricted Stock [Member]

Restricted Stock [Member]

Restricted Stock [Member]

Restricted Stock [Member]

Variable Interest Entity, Measure of Activity, Expense

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$39,000,000

$28,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

3,000

3,000

3,000

15,000

12,000

12,000

'

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value

'

'

'

'

'

$31.20

'

'

'

$29.48

'

'

'

'

$31.20

$29.48

$29.05

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period

'

'

'

'

'

'

'

'

'

'

'

'

'

'

9,500

7,000

4,500

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Share-based Compensation

'

'

'

'

'

'

'

'

'

'

'

'

'

'

383,000

282,000

176,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Share Price

$33.70

$29

$27.36

$27.56

$28

'

'

'

$31.34

'

'

'

$29

$27.72

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Common Stock, Shares, Issued

36,800,000

71,200,000

40,500,000

49,700,000

26,900,000

356,200,000

'

'

57,500,000

338,900,000

'

'

71,200,000

32,200,000

356,200,000

338,900,000

149,300,000

'

'

'

108,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Stock Issued During Period, Value, New Issues

'

'

'

'

'

'

'

'

'

'

'

'

'

'

1,803,000,000

3,601,000,000

4,376,000,000

'

'

1,000,000

1,000,000

1,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Stock Repurchase Program, Authorized Amount

'

'

'

'

'

'

'

'

'

'

'

'

'

'

1,000,000,000

500,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Stock Repurchased During Period, Shares

'

'

'

'

'

'

'

'

'

'

'

'

'

'

-40,200,000

-2,700,000

'

'

'

-40,300,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Treasury Stock Acquired, Average Cost Per Share

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$21.25

$29

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Stock Repurchased During Period, Value

'

'

'

'

'

'

'

'

'

'

'

'

'

'

-856,000,000

-77,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Stock Repurchase Program, Remaining Authorized Repurchase Amount

'

'

'

'

'

'

'

'

'

'

'

'

'

'

66,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Accumulated Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

-1,087,000,000

2,040,000,000

1,001,000,000

-28,000,000

'

'

'

'

'

'

'

'

'

'

'

'

Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Net of Tax

'

'

'

'

'

-311,000,000

833,000,000

-2,813,000,000

-837,000,000

-734,000,000

1,190,000,000

689,000,000

-106,000,000

'

-3,127,000,000

1,039,000,000

1,029,000,000

'

'

'

'

'

'

2,235,000,000

-4,535,000,000

2,235,000,000

1,512,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

Other Comprehensive Income Reclassification Adjustment For Sale Of Security Reversal Of Prior Period Unrealized Gain And Losses On Realization

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

-1,196,000,000

1,408,000,000

-1,196,000,000

-483,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax

'

'

'

'

'

46,000,000

47,000,000

48,000,000

49,000,000

50,000,000

51,000,000

52,000,000

52,000,000

'

189,000,000

205,000,000

-650,000,000

'

'

'

'

'

'

'

'

'

'

'

189,000,000

194,000,000

'

'

54,000,000

'

'

'

'

'

'

'

Total Reclass of Other Comprehensive Income

'

'

'

'

'

'

'

'

'

'

'

'

'

'

1,597,000,000

-991,000,000

-289,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Other comprehensive income (loss)

'

'

'

'

'

-265,000,000

880,000,000

-2,765,000,000

-788,000,000

-684,000,000

1,241,000,000

741,000,000

-54,000,000

'

-2,938,000,000

1,244,000,000

379,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Common Stock, Capital Shares Reserved for Future Issuance

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

16,700,000

'

'

'

21,700,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Preferred Stock, Shares Authorized

'

'

'

'

'

3,100,000

'

'

'

'

'

'

'

'

3,100,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Public offering price per share

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$24.21

Public offering of common stock

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

57,500,000

117,400,000

159,300,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Proceeds from Issuance of Common Stock

1,240,000,000

2,063,000,000

1,108,000,000

1,369,000,000

719,000,000

'

'

'

'

'

'

'

'

892,000,000

1,803,000,000

3,601,000,000

4,377,000,000

'

'

'

3,303,000,000

4,088,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Deferred Gain (Loss) on Discontinuation of Interest Rate Fair Value Hedge

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

-296,000,000

-690,000,000

-485,000,000

-40,000,000

'

'

'

'

'

'

'

'

Accumulated Other Comprehensive Income (Loss), Net of Tax

'

'

'

'

'

-1,383,000,000

'

'

'

1,555,000,000

'

'

'

'

-1,383,000,000

1,555,000,000

311,000,000

-68,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number

'

'

'

'

'

27,000

'

'

'

21,500

'

'

'

'

27,000

21,500

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant

'

'

'

'

'

47,500

'

'

'

'

'

'

'

'

47,500

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Proceeds from Issuance of Preferred Stock and Preference Stock

'

'

'

'

'

'

'

'

'

'

'

$167,000,000

'

'

$0

$167,000,000

$0

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Stockholders_Equity_Details

Stockholders' Equity (Details) (USD $)

1 Months Ended

3 Months Ended

12 Months Ended

12 Months Ended

12 Months Ended

9 Months Ended

12 Months Ended

12 Months Ended

3 Months Ended

12 Months Ended

12 Months Ended

Jul. 31, 2012

Mar. 31, 2012

Nov. 30, 2011

Jun. 30, 2011

Jan. 31, 2011

Dec. 31, 2013

Sep. 30, 2013

Jun. 30, 2013

Mar. 31, 2013

Dec. 31, 2012

Sep. 30, 2012

Jun. 30, 2012

Mar. 31, 2012

Mar. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2010

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Sep. 30, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2010

Dec. 31, 2013

Dec. 31, 2011

Dec. 31, 2012

Dec. 31, 2010

Dec. 31, 2011

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2012

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Common Stock [Member]

Common Stock [Member]

Common Stock [Member]

At the Market Offering Program [Member]

Dividend Reinvestment And Direct Stock Purchase Plan [Member]

Restricted Stock [Member]

Restricted Stock [Member]

Restricted Stock [Member]

Restricted Stock [Member]

Restricted Stock [Member]

Restricted Stock [Member]

Agency Securities [Member]

Agency Securities [Member]

Agency Securities [Member]

Agency Securities [Member]

Agency Securities [Member]

Discontinuation of Election to Account for Interest Rate Swaps as Designated Cash Flow Hedges [Member]

Discontinuation of Election to Account for Interest Rate Swaps as Designated Cash Flow Hedges [Member]

Discontinuation of Election to Account for Interest Rate Swaps as Designated Cash Flow Hedges [Member]

Discontinuation of Election to Account for Interest Rate Swaps as Designated Cash Flow Hedges [Member]

Interest Rate Swap [Member]

At-the-Market Offering Program [Member]

At-the-Market Offering Program [Member]

Dividend Reinvestment And Direct Stock Purchase Plan [Member]

Interest Rate Swap [Member]

Interest Rate Swap [Member]

Interest Rate Swap [Member]

Forward Contracts [Member]

Forward Contracts [Member]

Interest Rate Swap [Member]

Interest Rate Swap [Member]

Interest Rate Swap [Member]

Director [Member]

Director [Member]

Director [Member]

Each Director [Member]

Each Director [Member]

Each Director [Member]

Discontinuation of Election to Account for Interest Rate Swaps as Designated Cash Flow Hedges [Member]

Agency Securities [Member]

Agency Securities [Member]

Agency Securities [Member]

Interest Rate Swap [Member]

Notional Amount

'

'

'

'

'

$2,119,000,000

'

'

'

$12,477,000,000

'

'

'

'

$2,119,000,000

$12,477,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$150,000,000

[1]

$1,700,000,000

'

'

'

Share Price

$33.70

$29

$27.36

$27.56

$28

'

'

'

$31.34

'

'

'

$29

$27.72

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$31.41

$29.25

'

'

'

'

'

'

'

'

'

Common Stock, Shares, Issued

36,800,000

71,200,000

40,500,000

49,700,000

26,900,000

356,200,000

'

'

57,500,000

338,900,000

'

'

71,200,000

32,200,000

356,200,000

338,900,000

149,300,000

'

'

108,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

9,500,000

9,400,000

500,000

'

'

'

'

'

'

'

'

Proceeds from Issuance of Common Stock

1,240,000,000

2,063,000,000

1,108,000,000

1,369,000,000

719,000,000

'

'

'

'

'

'

'

'

892,000,000

1,803,000,000

3,601,000,000

4,377,000,000

'

'

3,303,000,000

4,088,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

298,000,000

273,000,000

15,000,000

'

'

'

'

'

'

'

'

Accumulated Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

-1,087,000,000

2,040,000,000

1,001,000,000

-28,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Other Comprehensive Income Reclassification Adjustment For Sale Of Security Reversal Of Prior Period Unrealized Gain And Losses On Realization

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

-1,196,000,000

1,408,000,000

-1,196,000,000

-483,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Spread Over LIBOR

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'42

'43

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Preferred Stock, Shares Authorized

'

'

'

'

'

10,000,000

'

'

'

10,000,000

'

'

'

'

10,000,000

10,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Preferred stock, shares issued

'

'

'

'

'

6,900,000

'

'

'

6,900,000

'

6,900,000

'

'

6,900,000

6,900,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Issuance of common stock, value

'

'

'

'

'

'

'

'

'

'

'

'

'

'

1,803,000,000

3,601,000,000

4,376,000,000

'

1,000,000

1,000,000

1,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Public offering of common stock

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

57,500,000

117,400,000

159,300,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Shares available for issuance

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

16,700,000

21,700,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Preferred Stock, Par or Stated Value Per Share

'

'

'

'

'

$0.01

'

'

'

$0.01

'

'

'

'

$0.01

$0.01

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Proceeds from Issuance of Preferred Stock and Preference Stock

'

'

'

'

'

'

'

'

'

'

'

167,000,000

'

'

0

167,000,000

0

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Preferred Stock, Dividend Rate, Percentage

'

'

'

'

'

'

'

'

'

'

'

'

'

'

8.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Preferred Stock Authorized, but not Issued

'

'

'

'

'

3,100,000

'

'

'

'

'

'

'

'

3,100,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Preferred Stock, Liquidation Preference Per Share

'

'

'

'

'

$25

'

'

'

'

'

'

'

'

$25

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Stock Repurchase Program, Authorized Amount

'

'

'

'

'

'

'

'

'

'

'

'

'

'

1,000,000,000

500,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Stock Repurchased During Period, Shares

'

'

'

'

'

'

'

'

'

'

'

'

'

'

-40,200,000

-2,700,000

'

'

-40,300,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Treasury Stock Acquired, Average Cost Per Share

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$21.25

$29

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Stock Repurchased During Period, Value

'

'

'

'

'

'

'

'

'

'

'

'

'

'

-856,000,000

-77,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

15,000

12,000

12,000

3,000

3,000

3,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value

'

'

'

'

'

$31.20

'

'

'

$29.48

'

'

'

'

$31.20

$29.48

$29.05

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period

'

'

'

'

'

'

'

'

'

'

'

'

'

'

9,500

7,000

4,500

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value

'

'

'

'

'

'

'

'

'

'

'

'

'

'

290,000

222,000

131,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Share-based Compensation

'

'

'

'

'

'

'

'

'

'

'

'

'

'

383,000

282,000

176,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number

'

'

'

'

'

27,000

'

'

'

21,500

'

'

'

'

27,000

21,500

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized

'

'

'

'

'

481,919

'

'

'

397,415

'

'

'

'

481,919

397,415

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant

'

'

'

'

'

47,500

'

'

'

'

'

'

'

'

47,500

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax

'

'

'

'

'

46,000,000

47,000,000

48,000,000

49,000,000

50,000,000

51,000,000

52,000,000

52,000,000

'

189,000,000

205,000,000

-650,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

189,000,000

194,000,000

'

'

54,000,000

'

'

'

'

'

'

'

'

0

0

-844,000,000

Total Reclass of Other Comprehensive Income

'

'

'

'

'

'

'

'

'

'

'

'

'

'

1,597,000,000

-991,000,000

-289,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Deferred Gain (Loss) on Discontinuation of Interest Rate Fair Value Hedge

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

-296,000,000

-690,000,000

-485,000,000

-40,000,000

'

'

'

'

'

'

'

'

'

'

'

'

Accumulated Other Comprehensive Income (Loss), Net of Tax

'

'

'

'

'

-1,383,000,000

'

'

'

1,555,000,000

'

'

'

'

-1,383,000,000

1,555,000,000

311,000,000

-68,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Net of Tax

'

'

'

'

'

-311,000,000

833,000,000

-2,813,000,000

-837,000,000

-734,000,000

1,190,000,000

689,000,000

-106,000,000

'

-3,127,000,000

1,039,000,000

1,029,000,000

'

'

'

'

'

'

'

'

'

'

'

'

2,235,000,000

-4,535,000,000

2,235,000,000

1,512,000,000

'

'

'

'

'

'

'

'

'

-4,535,000,000

2,235,000,000

668,000,000

'

'

'

'

'

Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent

'

'

'

'

'

($265,000,000)

$880,000,000

($2,765,000,000)

($788,000,000)

($684,000,000)

$1,241,000,000

$741,000,000

($54,000,000)

'

($2,938,000,000)

$1,244,000,000

$379,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

[1]

2.Cost basis represents the forward price to be paid/(received) for the underlying agency security.

Quarterly_Results_Details

Quarterly Results (Details) (USD $)	3 Months Ended								12 Months Ended
In Millions, except Per Share data, unless otherwise specified	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Interest Income, Securities, Mortgage Backed	$542	$558	$545	$547	$570	$520	$504	$514	$2,193	$2,109	$1,109
Interest Expense	120	145	131	140	147	139	120	106	536	512	285
Net interest income	422	413	414	407	423	381	384	408	1,657	1,597	824
Gain (Loss) on Sales of Mortgage Backed Securities (MBS)	-667	-733	17	-26	353	210	417	216	-1,408	1,196	473
Gain (loss) on derivative instruments and other securities, net	184	-339	1,444	-98	89	-460	-1,029	47	1,191	-1,353	-447
Total other income (loss), net	-483	-1,072	1,461	-124	442	-250	-612	263	-217	-157	26
Management fees	31	35	37	33	31	32	28	22	136	113	55
General and Administrative Expense	6	7	9	9	9	8	8	6	32	31	19
Total expenses	37	42	46	42	40	40	36	28	168	144	74
Income (loss) before income tax (benefit)	-98	-701	1,829	241	825	91	-264	643	1,272	1,296	776
Excise and REIT Income tax	3	0	0	10	15	5	-3	2	13	19	6
Net income (loss)	-101	-701	1,829	231	810	86	-261	641	1,259	1,277	770
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Net of Tax	-311	833	-2,813	-837	-734	1,190	689	-106	-3,127	1,039	1,029
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax	46	47	48	49	50	51	52	52	189	205	-650
Other comprehensive (loss) income	-265	880	-2,765	-788	-684	1,241	741	-54	-2,938	1,244	379
Comprehensive income	-366	179	-936	-557	126	1,327	480	587	-1,679	2,521	1,149
Dividend on preferred stock	3	3	3	3	3	3	3	0	14	10	0
Comprehensive income available to common shareholders	-369	176	-939	-560	123	1,324	477	587	-1,693	2,511	1,149
Net income (loss) available (attributable) to common shareholders	-104	-704	1,826	228	807	83	-264	641	1,245	1,267	770
Weighted average number of common shares outstanding-basic and diluted	373	390.6	396.4	356.2	340.3	332.8	301	240.6	379.1	303.9	153.3
Net income (loss) per common share - basic and diluted	($0.28)	($1.80)	$4.61	$0.64	$2.37	$0.25	($0.88)	$2.66	$3.28	$4.17	$5.02
Comprehensive income per common share - basic and diluted	($0.99)	$0.45	($2.37)	($1.57)	$0.36	$3.98	$1.58	$2.44	($4.47)	$8.26	$7.50
Common Stock, Dividends, Per Share, Declared	$0.65	$0.80	$1.05	$1.25	$1.25	$1.25	$1.25	$1.25	'	'	'
Discontinuation of Election to Account for Interest Rate Swaps as Designated Cash Flow Hedges [Member]	'	'	'	'	'	'	'	'	'	'	'
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax	'	'	'	'	'	'	'	'	$189	'	$194