AGNC Investment (AGNC) 10-K 22 Feb 19 2018 Q4 Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Billions	12 Months Ended
	Dec. 31, 2018	Jan. 31, 2019	Jun. 30, 2018
Document and Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q4
Entity Registrant Name	AGNC Investment Corp.
Entity Central Index Key	1,423,689
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Current Fiscal Year End Date	--12-31
Entity Common Stock, Shares Outstanding		536,339,092
Trading Symbol	AGNC
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Shell Company	false
Entity Public Float			$ 6.8

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Assets:
Agency securities, at fair value (including pledged securities of $78,619 and $53,055, respectively)	$ 82,291	$ 55,506
Agency securities transferred to consolidated variable interest entities, at fair value (pledged securities)	436	662
Credit risk transfer securities, at fair value (including pledged securities of $141 and $0, respectively)	1,012	876
Non-Agency securities, at fair value (including pledged securities of $45 and $0, respectively)	548	36
U.S. Treasury securities, at fair value	46	0
REIT equity securities, at fair value	0	29
Cash and cash equivalents	921	1,046
Restricted cash and cash equivalents	599	317
Derivative assets, at fair value	273	205
Receivable for investment securities sold (pledged securities)	489	0
Receivable under reverse repurchase agreements	21,813	10,961
Goodwill and other intangible assets, net	526	551
Other assets	287	187
Total assets	109,241	70,376
Liabilities:
Repurchase Agreements	75,717	50,296
Debt of consolidated variable interest entities, at fair value	275	357
Payable for investment securities purchased	1,204	95
Derivative liabilities, at fair value	84	28
Dividends payable	106	80
Obligation to return securities borrowed under reverse repurchase agreements, at fair value	21,431	10,467
Accounts payable and other liabilities	518	299
Total liabilities	99,335	61,622
Stockholders' equity:
7.750% Series B Cumulative Redeemable Preferred Stock (aggregate liquidation preference of $175)	169	169
7.000% Series C Fixed-to-Floating Rate Cumulative Redeemable Preferred Stock (aggregate liquidation preference of $325)	315	315
Common stock - $0.01 par value; 900 and 600 shares authorized, respectively; 536.3 and 391.3 shares issued and outstanding, respectively	5	4
Additional paid-in capital	13,793	11,173
Retained deficit	(3,433)	(2,562)
Accumulated other comprehensive loss	(943)	(345)
Total stockholders' equity	9,906	8,754
Total liabilities and stockholders' equity	$ 109,241	$ 70,376

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parentheticals) - USD ($) shares in Millions, $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Financial Instruments Owned and Pledged as Collateral [Line Items]
Security Owned and Pledged as Collateral, Fair Value	$ 79,182	$ 52,497
Preferred Stock B, Liquidation Preference, Value	175	175
Preferred Stock C, Liquidation Preference, Value	$ 325	$ 325
Common Stock, Par or Stated Value Per Share	$ 0.01	$ 0.01
Common Stock, Shares Authorized	900	600
Common Stock, Shares, Issued	536.3	391.3
Common Stock, Shares, Outstanding	536.3	391.3
Agency Securities [Member]
Financial Instruments Owned and Pledged as Collateral [Line Items]
Security Owned and Pledged as Collateral, Fair Value	$ 78,619	$ 53,055
Credit Risk Transfer Securities [Member]
Financial Instruments Owned and Pledged as Collateral [Line Items]
Security Owned and Pledged as Collateral, Fair Value	141	0
Mortgage-backed Securities, Issued by Private Enterprises [Member]
Financial Instruments Owned and Pledged as Collateral [Line Items]
Security Owned and Pledged as Collateral, Fair Value	45	0
US Treasury Securities [Member]
Financial Instruments Owned and Pledged as Collateral [Line Items]
Security Owned and Pledged as Collateral, Fair Value	437	185
Receivable for securities sold [Member]
Financial Instruments Owned and Pledged as Collateral [Line Items]
Security Owned and Pledged as Collateral, Fair Value	489	0
Asset Pledged as Collateral [Member] | US Treasury Securities [Member]
Financial Instruments Owned and Pledged as Collateral [Line Items]
Security Owned and Pledged as Collateral, Fair Value	$ 0	$ 0

Consolidated Statements Of Comp

Consolidated Statements Of Comprehensive Income - USD ($) shares in Millions, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Dividends declared per common share	$ 0.54	$ 0.54	$ 0.54	$ 0.54	$ 0.54	$ 0.54	$ 0.54	$ 0.54
Interest income:
Interest income	$ 604	$ 500	$ 414	$ 431	$ 386	$ 318	$ 293	$ 296	$ 1,949	$ 1,293	$ 1,321
Interest expense	418	312	237	206	174	140	112	98	1,173	524	394
Net interest income	186	188	177	225	212	178	181	198	776	769	927
Other gain (loss), net:
Gain (loss) on sale of investment securities, net	(21)	(40)	(74)	(2)	(16)	22	15	(84)	(137)	(63)	109
Unrealized loss on investment securities measured at fair value through net income, net	683	(363)	(94)	(523)	(65)	(31)	9	16	(297)	(71)	(6)
Gain (loss) on derivative instruments and other securities, net	(1,633)	430	298	738	271	131	(169)	(40)	(167)	193	(310)
Management Fee Income	0	46	4	4	4	4	4	4	54	16	8
Total other gain (loss), net:	(971)	73	134	217	194	126	(141)	(104)	(547)	75	(199)
Expenses:
Management fee expense									0	0	52
Compensation and benefits	11	14	10	10	12	10	10	10	45	42	19
Other operating expense	8	31	8	8	9	8	6	8	55	31	34
Total operating expense	19	45	18	18	21	18	16	18	100	73	105
Net income	(804)	216	293	424	385	286	24	76	129	771	623
Dividend on preferred stock	9	9	9	9	9	9	7	7	36	32	28
Issuance costs of redeemed preferred stock					0	6	0	0	0	6	0
Net income available to common stockholders	(813)	207	284	415	376	271	17	69	93	733	595
Other comprehensive income (loss):
Unrealized gain (loss) on available-for-sale securities, net	(361)	193	145	621	205	(90)	(121)	(46)	598	(52)	370
Unrealized gain on derivative instruments, net									0	0	39
Other comprehensive income (loss)									(598)	52	(331)
Comprehensive income (loss)	(443)	23	148	(197)	180	376	145	122	(469)	823	292
Comprehensive income (loss) available (attributable) to common stockholders	$ (452)	$ 14	$ 139	$ (206)	$ 171	$ 361	$ 138	$ 115	$ (505)	$ 785	$ 264
Weighted average number of common shares outstanding - basic	504.2	462.3	404.9	391.3	391.3	364.7	346.4	331	441.1	358.6	331.9
Weighted average number of common shares outstanding - diluted	504.2	462.7	405.2	391.5	391.5	364.9	346.5	331.1	441.4	358.7	331.9
Net income per common share - basic	$ (1.61)	$ 0.45	$ 0.70	$ 1.06	$ 0.96	$ 0.74	$ 0.05	$ 0.21	$ 0.21	$ 2.04	$ 1.79
Net income per common share - diluted									$ 0.21	$ 2.04	$ 1.79

Consolidated Statement of Stock

Consolidated Statement of Stockholders' Equity - USD ($) shares in Millions, $ in Millions	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings (Accumulated Deficit) [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Series A Preferred Stock [Member]Preferred Stock [Member]	Series B Preferred Stock [Member]Preferred Stock [Member]	Series C Preferred Stock [Member]Preferred Stock [Member]
Balance, value at Dec. 31, 2015	$ 7,971	$ 3	$ 10,048	$ (2,350)	$ (66)	$ 167	$ 169	$ 0
Balance, Common Stock, shares at Dec. 31, 2015		337.5
Net income (loss)	623			623
Other comprehensive income (loss):
Unrealized Gains and (Losses), Net	(370)				(370)
Amounts reclassified from accumulated OCI	39				(39)
Proceeds from Issuance of Preferred Stock and Preference Stock	0
Issuance costs of redeemed preferred stock	0
Repurchase of common stock	(116)	$ 0	116
Payments for Repurchase of Common Stock	$ 116
Repurchase of common stock shares	(6.5)	(6.5)
Preferred dividends declared	$ (28)			(28)
Common dividends declared	(763)			(763)
Balance, value at Dec. 31, 2016	7,356	$ 3	9,932	(2,518)	(397)	167	169	0
Balance, Common Stock, shares at Dec. 31, 2016		331
Net income (loss)	771			771
Other comprehensive income (loss):
Unrealized Gains and (Losses), Net	52				52
Amounts reclassified from accumulated OCI	0
Adjustments to Additional Paid in Capital, Share-based Compensation and Exercise of Stock Options	4		4
Proceeds from Issuance of Preferred Stock and Preference Stock	$ 315
Stock Redeemed or Called During Period, Shares	(167)
Preferred Stock, Redemption Amount	$ (173)
Issuance costs of redeemed preferred stock	(6)
Stock Issued During Period, Shares, New Issues		60.3
Stock Issued During Period, Value, New Issues	1,238	$ 1	1,237
Payments for Repurchase of Common Stock	0
Preferred dividends declared	(32)			(32)
Common dividends declared	(777)			(777)
Balance, value at Dec. 31, 2017	$ 8,754	$ 4	11,173	(2,562)	(345)	0	169	315
Balance, Common Stock, shares at Dec. 31, 2017	391.3	391.3
Net income (loss)	$ 129			129
Other comprehensive income (loss):
Unrealized Gains and (Losses), Net	(598)				(598)
Amounts reclassified from accumulated OCI	0
Adjustments to Additional Paid in Capital, Share-based Compensation and Exercise of Stock Options	10		10
Proceeds from Issuance of Preferred Stock and Preference Stock	0
Issuance costs of redeemed preferred stock	0
Stock Issued During Period, Shares, New Issues		145
Stock Issued During Period, Value, New Issues	2,611	$ 1	2,610
Payments for Repurchase of Common Stock	0
Preferred dividends declared	(36)			(36)
Common dividends declared	(964)			(964)
Balance, value at Dec. 31, 2018	$ 9,906	$ 5	$ 13,793	$ (3,433)	$ (943)	$ 0	$ 169	$ 315
Balance, Common Stock, shares at Dec. 31, 2018	536.3	536.3

Consolidated Statements Of Cash

Consolidated Statements Of Cash Flows $ in Millions	12 Months Ended
	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Statement of Cash Flows [Abstract]
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	$ 1,520	$ 1,363	$ 1,282
Interest Paid, Including Capitalized Interest, Operating and Investing Activities	1,090	474	332
Operating activities:
Net income (loss)	129	771	623
Adjustments to reconcile net income to net cash provided by operating activities:
Amortization of premiums and discounts on mortgage-backed securities, net	331	378	400
Amortization of accumulated other comprehensive loss on interest rate swaps de-designated as qualifying hedges	0	0	39
Amortization of intangible assets	25	3	2
Stock based compensation	6	4	1
(Gain) loss on sale of investment securities, net	137	63	(109)
Unrealized loss on investment securities measured at fair value through net income, net	297	71	6
(Gain) loss on derivative instruments and other securities, net	167	(193)	310
(Increase) decrease in other assets	(100)	82	34
Increase in accounts payable and other accrued liabilities	121	81	46
Net cash provided by operating activities	1,113	1,260	1,352
Investing activities:
Purchases of Agency mortgage-backed securities	(42,586)	(35,920)	(20,836)
Purchases of credit risk transfer and non-Agency securities	(1,572)	(1,074)	(229)
Proceeds from sale of Agency mortgage-backed securities	8,132	18,701	18,030
Proceeds from sale of credit risk transfer and non-Agency securities	891	494	0
Principal collections on Agency mortgage-backed securities	7,170	6,869	8,114
Principal collections on credit risk transfer and non-Agency securities	15	5	23
Payments on U.S. Treasury securities	(10,829)	(11,756)	(4,483)
Proceeds from U.S. Treasury securities	21,308	14,557	10,393
Net payments on reverse repurchase agreements	(10,571)	(3,162)	(6,003)
Net proceeds from (payments on) derivative instruments	76	253	(1,292)
Purchase of AGNC Mortgage Management, LLC, net of cash acquired	0	0	(555)
Net proceeds from (payments on) other investing activity	30	(28)	39
Net cash (used in) provided by investing activities	(27,936)	(11,061)	3,201
Financing activities:
Proceeds from repurchase arrangements	2,031,463	483,516	217,538
Payments on repurchase agreements	(2,006,042)	(471,078)	(221,434)
Proceeds from Federal Home Loan Bank advances	0	0	2,098
Payments on Federal Home Loan Bank advances	0	(3,037)	(2,814)
Payments on debt of consolidated variable interest entities	(78)	(104)	(135)
Net proceeds from preferred stock issuance	0	315	0
Payment for preferred stock redemption	0	(173)	0
Net proceeds from common stock issuances	2,611	1,238	0
Payment for common stock repurchases	0	0	(116)
Cash dividends paid	(974)	(795)	(799)
Net cash (used in) provided by financing activities	26,980	9,882	(5,662)
Net change in cash and cash equivalents	157	81	$ (1,109)
Cash and cash equivalents at end of period	$ 921	$ 1,046

Organization

Organization	12 Months Ended
	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [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. Our common stock is traded on The Nasdaq Global Select Market under the symbol "AGNC." We are internally-managed, and our principal objective is to provide our stockholders with attractive risk-adjusted returns through a combination of monthly dividends and tangible net book value accretion. We generate income from the interest earned on our investments, net of associated borrowing and hedging costs, and net realized gains and losses on our investment and hedging activities. We operate 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 income. As a REIT, we will generally not be subject to U.S. federal or state corporate taxes on our taxable income to the extent that we distribute our annual taxable income to our stockholders on a timely basis. It is our intention to distribute 100% of our taxable income, after application of available tax attributes, within the limits prescribed by the Internal Revenue Code, which may extend into the subsequent tax year. We invest primarily in Agency residential mortgage-backed securities ("Agency RMBS") for which the principal and interest payments are guaranteed by a U.S. Government-sponsored enterprise ("GSE") or a U.S. Government agency. We may also invest in other types of mortgage and mortgage-related securities, such as credit risk transfer ("CRT") securities and non-Agency residential and commercial mortgage-backed securities ("non-Agency RMBS" and "CMBS," respectively), where repayment of principal and interest is not guaranteed by a GSE or U.S. Government agency or in other investments in, or related to, the housing, mortgage or real estate markets. We fund our investments primarily through borrowings structured as repurchase agreements. Prior to July 1, 2016, we were externally managed by AGNC Management, LLC, our former manager. On July 1, 2016, we completed the acquisition of all the outstanding membership interests of AGNC Mortgage Management, LLC, the parent company of our for former manager, from American Capital Asset Management, LLC ("AMM"), a wholly owned portfolio company of American Capital, Ltd.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2018
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 all subsidiaries and variable interest entities for which we are the primary beneficiary. Significant intercompany accounts and transactions have been eliminated. Adoption of Accounting Standard Updates As of January 1, 2018, we adopted Accounting Standards Update ("ASU") 2014-09, Revenue from Contracts with Customers (Topic 606), and ASU 2016-18 , Statement of Cash Flows (Topic 230) - Restricted Cash. The adoption of ASU 2014-09 resulted in reclassification of expense reimbursements from an other operating expense offset to management fee income on the consolidated statements of comprehensive income. Net income was not impacted. The adoption of ASU 2016-18 resulted in the presentation of restricted cash with cash and cash equivalents on the consolidated statements of cash flows when reconciling the total beginning and ending amounts. Our prior period results have been revised to conform to the current presentation. 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 (loss) available (attributable) to common stockholders 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. 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 and Cash Equivalents Restricted cash and cash equivalents includes cash and cash equivalents pledged as collateral for clearing and executing trades, repurchase agreements and other borrowings, and interest rate swaps and other derivative instruments. Restricted cash and cash equivalents are carried at cost, which approximates fair value. Investment Securities Agency RMBS consist of residential mortgage pass-through securities and collateralized mortgage obligations ("CMOs") guaranteed by the Federal National Mortgage Association ("Fannie Mae"), Federal Home Loan Mortgage Corporation ("Freddie Mac," and together with Fannie Mae, the "GSEs") or the Government National Mortgage Association ("Ginnie Mae"). CRT securities are risk sharing instruments issued by the GSEs, and similarly structured transactions issued by third-party market participants, that transfer a portion of the risk associated with credit losses within pools of conventional residential mortgage loans from the GSEs and/or third parties to private investors. Unlike Agency RMBS, full repayment of the original principal balance of CRT securities is not guaranteed by a GSE or U.S. Government agency; rather, "credit risk transfer" is achieved by writing down the outstanding principal balance of the CRT securities if credit losses on a related pool of loans exceed certain thresholds. By reducing the amount that they are obligated to repay to holders of CRT securities, the GSEs and/or other third parties offset credit losses on the related loans. Non-Agency RMBS and CMBS (together, "Non-Agency MBS") are backed by residential and commercial mortgage loans, respectively, packaged and securitized by a private institution, such as a commercial bank. Non-Agency MBS typically benefit from credit enhancements derived from structural elements, such as subordination, overcollateralization or insurance, but nonetheless carry a higher level of credit exposure than Agency RMBS. Accounting Standards Codification ("ASC") Topic 320, Investments—Debt and Equity Securities , 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. Alternatively, we may elect the fair value option of accounting for securities pursuant to ASC Topic 825, Financial Instruments . Prior to fiscal year 2017, we primarily designated our investment securities as available-for-sale. On January 1, 2017, we began electing the fair value option of accounting for all investment securities acquired after fiscal year 2016. Consequently, all of our securities are reported at fair value on our consolidated balance sheet. Unrealized gains and losses on securities classified as available-for-sale are reported in accumulated other comprehensive income ("OCI"). Unrealized gains and losses on securities for which we elected the fair value option or are classified as trading are reported in net income through other gain (loss) during the period in which they occur. Upon the sale of a security designated as available-for-sale, 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. In our view, the election of the fair value option simplifies the accounting for investment securities and more appropriately reflects the results of our operations for a reporting period, as the fair value changes for these assets are presented in a manner consistent with the presentation and timing of the fair value changes of our derivative instruments. We estimate the fair value of our investment securities based on prices provided by multiple third-party pricing services and non-binding dealer quotes (collectively "pricing sources"). These pricing sources use various valuation approaches, including market and income approaches, using "Level 2" inputs. The pricing sources primarily utilize a matrix pricing technique that interpolates the estimated fair value of our Agency RMBS based on observed quoted prices for forward contracts in the Agency RMBS "to-be-announced" market ("TBA securities") of the same coupon, maturity and issuer, adjusted to reflect the specific characteristics of the pool of mortgages underlying the Agency security, which may include maximum loan balance, loan vintage, loan-to-value ratio, geography and other characteristics as may be appropriate. The pricing sources may also utilize discounted cash flow model-derived pricing techniques to estimate the fair value of investment securities. Such models incorporate market-based discount rate assumptions based on observable inputs such as recent trading activity, credit data, volatility statistics, benchmark interest rate curves and other market data that are current as of the measurement date and may include certain unobservable inputs, such as assumptions of future levels of prepayment, defaults and loss severities. We review the pricing estimates obtained from the pricing sources and perform procedures to validate their reasonableness. Refer to Note 8 for further discussion of fair value measurements. We evaluate our investments designated as available-for-sale 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 exists 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. We did not recognize OTTI charges on our investment securities for fiscal years 2018, 2017 or 2016. 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 Agency RMBS and non-Agency MBS of high credit quality are amortized or accreted into interest income, respectively, over the projected lives of the securities, including contractual payments and estimated prepayments, using the effective interest method in accordance with ASC Subtopic 310-20, Receivables—Nonrefundable Fees and Other Costs . We estimate long-term prepayment speeds of our mortgage securities using a third-party service and market data. The third-party service provider estimates prepayment speeds using models that incorporate the forward yield curve, current mortgage rates, mortgage rates of the outstanding loans, age and size of the outstanding loans, loan-to-value ratios, interest rate 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 third-party estimates. We review our actual and anticipated prepayment experience on at least a quarterly basis and effective yields are recalculated when differences arise between (i) our previously estimated future prepayments and (ii) actual prepayments to date and our current 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. At the time we purchase CRT securities and non-Agency MBS that are not of high credit quality, we determine an effective yield based on our estimate of the timing and amount of future cash flows and our cost basis. Our initial cash flow estimates for these investments are based on our observations of current information and events and include assumptions related to interest rates, prepayment rates and the impact of default and severity rates on the timing and amount of credit losses. On at least a quarterly basis, we review the estimated cash flows and make appropriate adjustments based on inputs and analysis received from external sources, internal models, and our judgment regarding such inputs and other factors. Any resulting changes in effective yield are recognized prospectively based on the current amortized cost of the investment adjusted for credit impairments, if any. Repurchase Agreements We finance the acquisition of securities for our investment portfolio primarily through repurchase transactions under master repurchase agreements. Pursuant to ASC Topic 860, Transfers and Servicing , we account for repurchase transactions as collateralized financing transactions, which are carried at their contractual amounts (cost), plus accrued interest. Our repurchase agreements typically have maturities of less than one year but may extend up to five years or more. Interest rates on our repurchase agreements generally correspond to one or three-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 borrow securities to cover short sales of U.S. Treasury securities through reverse repurchase transactions under our master repurchase agreements (see Derivative 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 typically have maturities of 30 days or less. The fair value of our reverse repurchase agreements is assumed to equal cost as the interest rates are considered to be at market. Derivative Instruments We use a variety of derivative instruments to hedge a portion of our exposure to market risks, including interest rate, prepayment, extension and liquidity risks. 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 primary instruments that we use are interest rate swaps, options to enter into interest rate swaps ("swaptions"), U.S. Treasury securities and U.S. Treasury futures contracts. We also use forward contracts in the Agency RMBS "to-be-announced" market, or TBA securities, to invest in and finance Agency securities as well as to periodically reduce our exposure to Agency RMBS. 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 our accompanying consolidated balance sheets and to measure those instruments at fair value. None of our derivative instruments have been designated as hedging instruments for accounting purposes under the provisions of ASC 815, consequently changes in the fair value of our derivative instruments are reported in gain (loss) on derivative instruments and other securities, net in our consolidated statements of comprehensive income. Our derivative agreements generally contain provisions that allow for netting or setting off derivative assets and liabilities with the 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 derivative instruments creates exposure to credit risk relating to potential losses that could be recognized if the counterparties to these instruments fail to perform their obligations under the contracts. Our derivative agreements require that we post or receive collateral to mitigate such risk. We also attempt to minimize our risk of loss by limiting our counterparties to registered central clearing exchanges and major financial institutions with acceptable credit ratings, monitoring positions with individual counterparties and adjusting posted collateral as required. Interest rate swap agreements We use interest rate swaps to economically hedge the variable cash flows associated with our borrowings made under repurchase agreements. Under our interest rate swap agreements, we typically pay a fixed rate and receive a floating rate based on one or three-month LIBOR ("payer swaps") with terms up to 20 years. The majority of our interest rate swaps are centrally cleared through a registered commodities exchange. We value centrally cleared interest rate swaps using the daily settlement price, or fair value, determined by the clearing exchange based on a pricing model that references observable market inputs, including LIBOR, swap rates and the forward yield curve. Our centrally cleared swaps require that we post an "initial margin" amount determined by the clearing exchange, which is generally intended to be set at a level sufficient to protect the exchange from the interest rate swap's maximum estimated single-day price movement. We also exchange daily settlements of "variation margin" based upon changes in fair value, as measured by the exchange. Pursuant to rules governing central clearing activities, we recognize variation margin settlements as a direct reduction of the carrying value of the interest rate swap asset or liability. We value non-centrally cleared swaps using a combination of third-party valuations obtained from pricing services and the swap counterparty. The third-party valuations are model-driven using observable inputs, including LIBOR, swap rates and the forward yield curve. We also consider 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 assess 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, more rapid changes in interest rates on the performance of our investment portfolio. 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 interest rate swaption agreements are not subject to central clearing. The premium paid for interest rate swaptions is reported as an asset in our consolidated balance sheets. 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. The difference between the premium paid 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 and the premium paid. TBA securities A TBA security is a forward contract for the purchase or sale of Agency RMBS at a predetermined price, face amount, issuer, coupon and stated maturity on an agreed-upon future date. The specific Agency RMBS to be delivered into the contract are not known until shortly before the settlement date. We may choose, prior to settlement, to move the settlement of these securities out to a later date by entering into an offsetting TBA position, net settling the offsetting positions for cash, and simultaneously purchasing or selling a similar TBA contract for a later settlement date (together referred to as a "dollar roll transaction"). The Agency securities purchased or sold for a forward settlement date are typically priced at a discount to equivalent securities settling in the current month. This difference, or "price drop," is the economic equivalent of interest income on the underlying Agency securities, less an implied funding cost, over the forward settlement period (referred to as "dollar roll income"). Consequently, forward purchases of Agency securities and dollar roll transactions represent a form of off-balance sheet financing. We account for TBA contracts as derivative instruments since either the TBA contracts do not settle in the shortest period of time possible or we cannot assert that it is probable at inception and throughout the term of the TBA contract that we will physically settle the contract on the settlement date. We account for TBA dollar roll transactions as a series of derivative transactions. We estimate the fair value of TBA securities based on similar methods used to value our Agency RMBS securities. U.S. Treasury securities We use U.S. Treasury securities and U.S. Treasury futures contracts to mitigate the potential impact of changes in interest rates on the performance of our portfolio. We borrow U.S. Treasury securities under reverse repurchase agreements to cover short sales of U.S. Treasury securities. We account for these as securities borrowing transactions and recognize an obligation to return the borrowed securities at fair value on our accompanying consolidated balance sheets based on the value of the underlying U.S. Treasury security as of the reporting date. Gains and losses associated with 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. Prior to fiscal year 2016, we entered into transactions involving CMO trusts for which we determined we are the primary beneficiary given our level of control in the selection of Agency RMBS assets transferred to the CMO trust. Agency RMBS 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 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 the fair value of the Agency RMBS transferred to consolidated VIEs, less the fair value of our retained interests, which are measured on a market approach using "Level 2" inputs from third-party pricing services and dealer quotes. The fair value of the Agency RMBS transferred to the consolidated VIEs and the fair value of our retained interests are based on more observable inputs than inputs used to independently determine the value of our consolidated debt. As of December 31, 2018 and 2017 , debt of consolidated VIEs, at fair value, was $275 million and $357 million , respectively, had a weighted average interest rate of LIBOR plus 40 and 37 basis points, respectively, and an estimated weighted average life of 6.1 years and 5.7 years, respectively. Stock-Based Compensation We measure and recognize compensation expense for all stock-based payment awards made to employees and independent directors based on their fair values. Stock-based awards issued under our equity incentive plan include time-based and performance-based restricted stock unit awards ("RSU" and "PSU" awards, respectively). An RSU and PSU awards are an agreement to issue an equivalent number of shares of our common stock, plus any equivalent shares for dividends declared on our common stock, at the time the award vests, or later if distribution of such shares has been deferred beyond the vesting date. RSU awards vest over a specified service period. PSU awards vest over a specified service period subject to achieving long-term performance criteria. We value RSU and PSU awards based on the fair value of our common stock on the date of grant. Compensation expense is recognized over each award’s respective service period. In the case of PSU awards, we estimate the probability that the performance criteria will be achieved and recognize expense only for those awards expected to vest. We reevaluate our estimates each reporting period and recognize a cumulative effect adjustment to expense if our estimates change from the prior period. We do not estimate forfeiture rates; rather, we adjust for forfeitures in the periods in which they occur. Shares underlying RSU and PSU awards are issued on the vesting dates, or later if distribution of such shares has been deferred beyond the vesting date, net of any minimum statutory tax withholdings to be paid by us on behalf of our employees. As a result, the actual number of shares issued will be fewer than the actual number of awards outstanding. When awards vest, we record a liability for withholding amounts to be paid by us as a reduction to additional paid-in capital. Goodwill and Other Intangible Asset, Net Goodwill is the cost of an acquisition in excess of the fair value of identified assets acquired and liabilities assumed and is recognized as an asset on our consolidated balance sheets. Acquired intangible assets that do not meet the criteria for recognition as a separate asset are included in goodwill. Goodwill is not subject to amortization but must be tested for impairment at least annually. Intangible assets meeting the criteria for recognition as separate assets are recorded at their respective fair market values at the date of acquisition. Intangible assets with an estimated useful life are amortized over their expected useful life. As of December 31, 2018 , we had $526 million of goodwill and, as of December 31, 2017, we had $526 million of goodwill and an intangible asset of $25 million associated with our management of MTGE Investment Corp. ("MTGE") (Nasdaq: MTGE) reported in goodwill and other intangible asset, net in our accompanying consolidated balance sheets related to our acquisition of AMM. We test goodwill for impairment on an annual basis and at interim periods when events or circumstances may make it more likely than not that an impairment has occurred. If a qualitative analysis indicates that there may be an impairment, a quantitative analysis is performed. The quantitative analysis requires that we compare the carrying value of the identified reporting unit comprising the goodwill to the reporting unit's fair value. If the reporting units' carrying value is greater than its fair value, an impairment charge is recognized to the extent the carrying amount of the reporting unit exceeds its fair value. During fiscal years 2018, 2017 or 2016, we did not recognize a goodwill impairment charge. During fiscal year 2018, we wrote-off the unamortized intangible asset balance due to the sale of MTGE to a third-party and corresponding termination of its management agreement (see Note 12). Loss Contingencies We evaluate the existence of any pending or threatened litigation or other potential claims against the Company in accordance with ASC Topic 450, Contingencies, which requires that we assess the likelihood and range of potential outcomes of any such matters. We are the defendant in three stockholder derivative lawsuits alleging that certain of our current and former directors and officers breached fiduciary duties and wasted corporate assets relating to past renewals of the management agreement with our former external manager and the internalization of our management on July 1, 2016. Although the outcomes of these cases cannot be predicted with certainty, we do not believe that these cases have merit or will result in a material liability, and, as of December 31, 2018 , we did not accrue a loss contingency related to these matters. Recent Accounting Pronouncements We consider the applicability and impact of all ASUs issued by the Financial Accounting Standards Board. ASUs not listed below were determined to be either not applicable, are not expected to have a significant impact on our consolidated financial statements when adopted or did not have a significant impact on our consolidated financial statements upon adoption. ASU 2016-13, Financial Instruments - Credit Losses (Topic 326): ASU 2016-13 changes the impairment model for most financial assets and certain other instruments. Allowances for credit losses on available-for-sale debt securities will be recognized, rather than direct reductions in the amortized cost of the investments. The new model also requires the estimation of lifetime expected credit losses and corresponding recognition of allowance for losses on trade and other receivables, held-to-maturity debt securities, loans, and other instruments held at amortized cost. The ASU requires certain recurring disclosures and is effective for annual periods, and interim periods within those annual periods, beginning on or after December 15, 2019, with early adoption permitted for annual periods, and interim periods within those annual periods, beginning on or after December 15, 2018. ASU 2016-13 is not expected to have a significant impact on our consolidated financial statements. ASU 2016-2, Leases (Topic 842): ASU 2016-2 requires lessees to recognize virtually all their leases on the balance sheet by recording a right-of-use asset and a lease liability. The lease liability will be measured at the present value of lease payments and the right-of-use asset will be based on the lease liability value, subject to adjustments. Leases can be classified as either operating leases or finance leases. Operating leases will result in straight-line lease expense, while finance leases will result in front-loaded expense. This guidance is effective for the Company on January 1, 2019. We have evaluated ASU 2016-2 and determined that it will not have a significant impact on our consolidated financial statements.

Investment Securities

Investment Securities	12 Months Ended
	Dec. 31, 2018
Investments, Debt and Equity Securities [Abstract]
Investment Securities	3 years and ≤ 5 years 5,518 5,586 3.35% 2.73% 7,499 7,518 3.31% 2.39% > 5 years and ≤10 years 72,503 73,588 3.92% 3.37% 45,977 46,398 3.75% 2.95% > 10 years 4,576 4,679 3.57% 3.30% 892 857 4.87% 4.74% Total $ 84,287 $ 85,569 3.86% 3.31% $ 57,080 $ 57,466 3.71% 2.89% The following table presents the gross unrealized loss and fair values of securities classified as available-for-sale by length of time that such securities have been in a continuous unrealized loss position as of December 31, 2018 and 2017 (in millions): Unrealized Loss Position For Less than 12 Months 12 Months or More Total Securities Classified as Available-for-Sale Fair Value Unrealized Loss Fair Value Unrealized Loss Fair Value Unrealized Loss December 31, 2018 $ 4,783 $ (72 ) $ 18,231 $ (878 ) $ 23,014 $ (950 ) December 31, 2017 $ 3,582 $ (15 ) $ 20,577 $ (451 ) $ 24,159 $ (466 ) We did not recognize OTTI charges on our investment securities during the periods presented on our consolidated statements of operations. As of the end of each respective reporting period, a decision had not been made to sell securities in an unrealized loss position and we did not believe it was more likely than not that we would be required to sell such securities before recovery of their amortized cost basis. The unrealized losses on our securities were not due to credit losses given the GSE or U.S. Government agency guarantees, but rather were due to changes in interest rates and prepayment expectations. However, as we continue to actively manage our portfolio, we may recognize additional realized losses on our investment securities upon selecting specific securities to sell. Gains and Losses on Sale of Investment Securities The following table is a summary of our net gain (loss) from the sale of investment securities for fiscal years 2018 , 2017 and 2016 by investment classification of accounting (in millions): Fiscal Year 2018 Fiscal Year 2017 Fiscal Year 2016 Investment Securities Available-for-Sale Securities 2 Fair Value Option Securities Total Available-for-Sale Securities 2 Fair Value Option Securities Total Available-for-Sale 2 Fair Value Option Securities Total Investment securities sold, at cost $ (4,306 ) $ (5,344 ) $ (9,650 ) $ (6,324 ) $ (12,913 ) $ (19,237 ) $ (17,907 ) $ — $ (17,907 ) Proceeds from investment securities sold 1 4,227 5,286 9,513 6,241 12,933 19,174 18,016 — 18,016 Net gain (loss) on sale of investment securities $ (79 ) $ (58 ) $ (137 ) $ (83 ) $ 20 $ (63 ) $ 109 $ — $ 109 Gross gain on sale of investment securities $ 6 $ 16 $ 22 $ 16 $ 48 $ 64 $ 123 $ — $ 123 Gross loss on sale of investment securities (85 ) (74 ) (159 ) (99 ) (28 ) (127 ) (14 ) — (14 ) Net gain (loss) on sale of investment securities $ (79 ) $ (58 ) $ (137 ) $ (83 ) $ 20 $ (63 ) $ 109 $ — $ 109 ________________________________ 1. Proceeds include cash received during the period, plus receivable for investment securities sold during the period as of period end. 2. See Note 9 for a summary of changes in accumulated OCI. Consolidated Variable Interest Entities As of December 31, 2018 and 2017 , our consolidated financial statements reflect the consolidation of certain variable interest entities ("VIEs") for which we have determined we are the primary beneficiary. The consolidated VIEs consist of CMO trusts backed by fixed or adjustable-rate Agency RMBS. 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 the 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." id="sjs-B4">Investment Securities As of December 31, 2018 and 2017 , our investment portfolio consisted of $84.3 billion and $57.1 billion of investment securities, at fair value, respectively, and $7.3 billion and $15.7 billion of TBA securities, at fair value, respectively. Our TBA position is reported at its net carrying value of $70 million and $3 million as of December 31, 2018 and 2017 , respectively, in derivative assets / (liabilities) on our accompanying consolidated balance sheets. The net carrying value of our TBA position represents the difference between the fair value of the underlying Agency security in the TBA contract and the cost basis or the forward price to be paid or received for the underlying Agency security. As of December 31, 2018 and 2017 , our investment securities had a net unamortized premium balance of $2.9 billion and $2.7 billion , respectively, including interest and principal-only securities. The following tables summarize our investment securities as of December 31, 2018 and 2017 , excluding TBA securities, (dollars in millions). Details of our TBA securities as of each of the respective dates are included in Note 5 . December 31, 2018 December 31, 2017 Investment Securities Amortized Cost Fair Value Amortized Fair Value Agency RMBS: Fixed rate $ 83,047 $ 81,753 $ 55,477 $ 55,026 Adjustable rate 212 213 278 283 CMO 588 583 629 631 Interest-only and principal-only strips 172 178 213 228 Total Agency RMBS 84,019 82,727 56,597 56,168 Non-Agency RMBS 264 266 7 7 CMBS 280 282 28 29 CRT securities 1,006 1,012 834 876 Total investment securities $ 85,569 $ 84,287 $ 57,466 $ 57,080 December 31, 2018 Agency RMBS Non-Agency Investment Securities Fannie Mae Freddie Mac Ginnie Mae RMBS CMBS CRT Total Available-for-sale securities: Par value $ 17,591 $ 5,673 $ 25 $ 6 $ — $ — $ 23,295 Unamortized discount (10 ) (2 ) — — — — (12 ) Unamortized premium 912 343 — — — — 1,255 Amortized cost 18,493 6,014 25 6 — — 24,538 Gross unrealized gains 4 2 1 — — — 7 Gross unrealized losses (686 ) (264 ) — — — — (950 ) Total available-for-sale securities, at fair value 17,811 5,752 26 6 — — 23,595 Securities remeasured at fair value through earnings: Par value 39,453 18,428 — 268 281 968 59,398 Unamortized discount (78 ) (9 ) — (10 ) (6 ) — (103 ) Unamortized premium 1,055 638 — — 5 38 1,736 Amortized cost 40,430 19,057 — 258 280 1,006 61,031 Gross unrealized gains 223 57 — 2 3 18 303 Gross unrealized losses (386 ) (243 ) — — (1 ) (12 ) (642 ) Total securities remeasured at fair value through earnings 40,267 18,871 — 260 282 1,012 60,692 Total securities, at fair value $ 58,078 $ 24,623 $ 26 $ 266 $ 282 $ 1,012 $ 84,287 Weighted average coupon as of December 31, 2018 3.82 % 3.87 % 3.37 % 3.83 % 4.58 % 5.86 % 3.86 % Weighted average yield as of December 31, 2018 1 3.28 % 3.28 % 2.04 % 4.22 % 4.68 % 5.16 % 3.31 % ________________________________ 1. Incorporates a weighted average future constant prepayment rate assumption of 7.9% based on forward rates as of December 31, 2018 . December 31, 2017 Agency RMBS Non-Agency Investment Securities Fannie Mae Freddie Mac Ginnie Mae RMBS CMBS CRT Total Available-for-sale securities: Par value $ 24,200 $ 8,219 $ 34 $ 7 $ — $ — $ 32,460 Unamortized discount (25 ) (3 ) — — — — (28 ) Unamortized premium 1,119 447 — — — — 1,566 Amortized cost 25,294 8,663 34 7 — — 33,998 Gross unrealized gains 98 22 1 — — — 121 Gross unrealized losses (325 ) (141 ) — — — — (466 ) Total available-for-sale securities, at fair value 25,067 8,544 35 7 — — 33,653 Securities remeasured at fair value through earnings: Par value 13,558 7,956 — — 29 801 22,344 Unamortized discount (34 ) — — — (1 ) — (35 ) Unamortized premium 711 415 — — — 33 1,159 Amortized cost 14,235 8,371 — — 28 834 23,468 Gross unrealized gains 26 2 — — 1 42 71 Gross unrealized losses (70 ) (42 ) — — — — (112 ) Total securities remeasured at fair value through earnings 14,191 8,331 — — 29 876 23,427 Total securities, at fair value $ 39,258 $ 16,875 $ 35 $ 7 $ 29 $ 876 $ 57,080 Weighted average coupon as of December 31, 2017 3.67 % 3.73 % 2.84 % 2.50 % 6.55 % 5.26 % 3.71 % Weighted average yield as of December 31, 2017 1 2.84 % 2.87 % 2.02 % 3.08 % 7.30 % 5.19 % 2.89 % ________________________________ 1. Incorporates a weighted average future constant prepayment rate assumption of 8.4% based on forward rates as of December 31, 2017 . As of December 31, 2018 and 2017 , our investments in CRT and non-Agency securities had the following credit ratings: December 31, 2018 December 31, 2017 CRT and Non-Agency Security Credit Ratings 1 CRT RMBS CMBS CRT RMBS CMBS AAA $ — $ 160 $ 52 $ — $ 7 $ — AA — 17 152 — — — A 17 33 15 1 — — BBB 25 43 53 34 — 29 BB 492 8 10 370 — — B 453 2 — 455 — — Not Rated 25 3 — 16 — — Total $ 1,012 $ 266 $ 282 $ 876 $ 7 $ 29 ________________________________ 1. Represents the lowest of Standard and Poor's ("S&P"), Moody's, Fitch, DBRS, Kroll Bond Rating Agency ("KBRA") and Morningstar credit ratings, stated in terms of the S&P equivalent rating as of each date. Our CRT securities reference the performance of loans underlying Agency RMBS issued by Fannie Mae or Freddie Mac, which were subject to their underwriting standards. As of December 31, 2018 , our CRT securities had floating rate coupons ranging from 3.9% to 9.5% , referenced to loans originated between 2011 and 2018 with weighted average coupons ranging from 3.8% to 4.8% . As of 2017 , our CRT securities had floating rate coupons ranging from 3.9% to 8.5% , referenced to loans originated between 2012 and 2017 with weighted average coupons ranging from 3.6% to 4.4% . The actual maturities of our investment securities are generally shorter than their 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, 2018 and 2017 , the weighted average expected constant prepayment rate ("CPR") over the remaining life of our aggregate investment portfolio was 7.9% and 8.4% , respectively. Our estimates can differ materially for different securities and thus our individual holdings have a wide range of projected CPRs. The following table summarizes our investments as of December 31, 2018 and 2017 according to their estimated weighted average life classification (dollars in millions): December 31, 2018 December 31, 2017 Estimated Weighted Average Life of Investment Securities Fair Value Amortized Cost Weighted Average Coupon Weighted Average Yield Fair Value Amortized Cost Weighted Average Coupon Weighted Average Yield ≥ 1 year and ≤ 3 years $ 1,690 $ 1,716 3.99% 2.64% $ 2,712 $ 2,693 3.90% 2.67% > 3 years and ≤ 5 years 5,518 5,586 3.35% 2.73% 7,499 7,518 3.31% 2.39% > 5 years and ≤10 years 72,503 73,588 3.92% 3.37% 45,977 46,398 3.75% 2.95% > 10 years 4,576 4,679 3.57% 3.30% 892 857 4.87% 4.74% Total $ 84,287 $ 85,569 3.86% 3.31% $ 57,080 $ 57,466 3.71% 2.89% The following table presents the gross unrealized loss and fair values of securities classified as available-for-sale by length of time that such securities have been in a continuous unrealized loss position as of December 31, 2018 and 2017 (in millions): Unrealized Loss Position For Less than 12 Months 12 Months or More Total Securities Classified as Available-for-Sale Fair Value Unrealized Loss Fair Value Unrealized Loss Fair Value Unrealized Loss December 31, 2018 $ 4,783 $ (72 ) $ 18,231 $ (878 ) $ 23,014 $ (950 ) December 31, 2017 $ 3,582 $ (15 ) $ 20,577 $ (451 ) $ 24,159 $ (466 ) We did not recognize OTTI charges on our investment securities during the periods presented on our consolidated statements of operations. As of the end of each respective reporting period, a decision had not been made to sell securities in an unrealized loss position and we did not believe it was more likely than not that we would be required to sell such securities before recovery of their amortized cost basis. The unrealized losses on our securities were not due to credit losses given the GSE or U.S. Government agency guarantees, but rather were due to changes in interest rates and prepayment expectations. However, as we continue to actively manage our portfolio, we may recognize additional realized losses on our investment securities upon selecting specific securities to sell. Gains and Losses on Sale of Investment Securities The following table is a summary of our net gain (loss) from the sale of investment securities for fiscal years 2018 , 2017 and 2016 by investment classification of accounting (in millions): Fiscal Year 2018 Fiscal Year 2017 Fiscal Year 2016 Investment Securities Available-for-Sale Securities 2 Fair Value Option Securities Total Available-for-Sale Securities 2 Fair Value Option Securities Total Available-for-Sale 2 Fair Value Option Securities Total Investment securities sold, at cost $ (4,306 ) $ (5,344 ) $ (9,650 ) $ (6,324 ) $ (12,913 ) $ (19,237 ) $ (17,907 ) $ — $ (17,907 ) Proceeds from investment securities sold 1 4,227 5,286 9,513 6,241 12,933 19,174 18,016 — 18,016 Net gain (loss) on sale of investment securities $ (79 ) $ (58 ) $ (137 ) $ (83 ) $ 20 $ (63 ) $ 109 $ — $ 109 Gross gain on sale of investment securities $ 6 $ 16 $ 22 $ 16 $ 48 $ 64 $ 123 $ — $ 123 Gross loss on sale of investment securities (85 ) (74 ) (159 ) (99 ) (28 ) (127 ) (14 ) — (14 ) Net gain (loss) on sale of investment securities $ (79 ) $ (58 ) $ (137 ) $ (83 ) $ 20 $ (63 ) $ 109 $ — $ 109 ________________________________ 1. Proceeds include cash received during the period, plus receivable for investment securities sold during the period as of period end. 2. See Note 9 for a summary of changes in accumulated OCI. Consolidated Variable Interest Entities As of December 31, 2018 and 2017 , our consolidated financial statements reflect the consolidation of certain variable interest entities ("VIEs") for which we have determined we are the primary beneficiary. The consolidated VIEs consist of CMO trusts backed by fixed or adjustable-rate Agency RMBS. 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 the 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.

Repurchase Agreements And Rever

Repurchase Agreements And Reverse Repurchase Agreements	12 Months Ended
	Dec. 31, 2018
Disclosure of Repurchase Agreements [Abstract]
Repurchase Agreements And Other Debt	1 to ≤ 3 months 20,991 2.57 % 56 16,150 1.50 % 50 > 3 to ≤ 6 months 2,218 2.65 % 167 7,287 1.50 % 130 > 6 to ≤ 9 months 200 3.19 % 208 2,361 1.66 % 225 > 9 to ≤ 12 months 950 2.80 % 279 202 1.64 % 297 > 12 to ≤ 24 months 2,200 2.91 % 438 1,700 1.84 % 468 > 24 to ≤ 36 months 625 3.11 % 776 2,200 1.80 % 803 > 36 to ≤ 48 months — — % — 625 1.90 % 1,141 Total $ 75,717 2.79 % 49 $ 50,296 1.57 % 116 As of December 31, 2018 and 2017 , $19.5 billion and $5.3 billion , respectively, of our repurchase agreements had a remaining maturity of one business day and none of our repurchase agreements were due on demand. As of December 31, 2018 , we had $10.7 billion of forward commitments to enter into repurchase agreements, with a weighted average forward start date of 9 days and a weighted average interest rate of 2.90% . As of December 31, 2018 and 2017 , 35% and 33% , respectively, of our repurchase agreement funding was sourced through our wholly-owned captive broker-dealer subsidiary, Bethesda Securities, LLC ("BES"). Amounts sourced through BES include funding from the General Collateral Finance Repo service ("GCF Repo") offered by the Fixed Income Clearing Corporation ("FICC"), which totaled 33% and 30% of our repurchase agreement funding outstanding as of December 31, 2018 and 2017 , respectively. Reverse Repurchase Agreements As of December 31, 2018 and 2017 , we had $21.8 billion and $11.0 billion , respectively, of reverse repurchase agreements outstanding used primarily to borrow securities to cover short sales of U.S. Treasury securities, for which we had associated obligations to return borrowed securities at fair value of $21.4 billion and $10.5 billion , respectively. As of December 31, 2018 and 2017 , $4.5 billion and $2.7 billion , respectively, of our reverse repurchase agreements were with the FICC sourced through BES." id="sjs-B4">Repurchase and Reverse Repurchase Agreements Repurchase Agreements We pledge our securities as collateral under our borrowings structured as repurchase agreements with financial institutions. Interest rates on our 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. If the fair value of our pledged securities declines, lenders will typically require us to post additional collateral or pay down borrowings to re-establish agreed upon collateral requirements, referred to as "margin calls." Similarly, if the fair value of our pledged securities increases, lenders may release collateral back to us. As of December 31, 2018 , we had met all margin call requirements. For additional information regarding our pledged assets, please refer to Note 6 . As of December 31, 2018 and 2017 , we had $75.7 billion and $50.3 billion , respectively, of repurchase agreements outstanding used to fund our investment portfolio. The terms and conditions of our repurchase agreements are typically negotiated on a transaction-by-transaction basis. Our repurchase agreements with original maturities greater than one year have floating interest rates based on an index plus or minus a fixed spread. The following table summarizes our borrowings under repurchase agreements by their remaining maturities as of December 31, 2018 and 2017 (dollars in millions): December 31, 2018 December 31, 2017 Remaining Maturity Repurchase Agreements Weighted Average Interest Rate Weighted Average Days to Maturity Repurchase Agreements Weighted Average Interest Rate Weighted Average Days to Maturity ≤ 1 month $ 48,533 2.88 % 9 $ 19,771 1.59 % 11 > 1 to ≤ 3 months 20,991 2.57 % 56 16,150 1.50 % 50 > 3 to ≤ 6 months 2,218 2.65 % 167 7,287 1.50 % 130 > 6 to ≤ 9 months 200 3.19 % 208 2,361 1.66 % 225 > 9 to ≤ 12 months 950 2.80 % 279 202 1.64 % 297 > 12 to ≤ 24 months 2,200 2.91 % 438 1,700 1.84 % 468 > 24 to ≤ 36 months 625 3.11 % 776 2,200 1.80 % 803 > 36 to ≤ 48 months — — % — 625 1.90 % 1,141 Total $ 75,717 2.79 % 49 $ 50,296 1.57 % 116 As of December 31, 2018 and 2017 , $19.5 billion and $5.3 billion , respectively, of our repurchase agreements had a remaining maturity of one business day and none of our repurchase agreements were due on demand. As of December 31, 2018 , we had $10.7 billion of forward commitments to enter into repurchase agreements, with a weighted average forward start date of 9 days and a weighted average interest rate of 2.90% . As of December 31, 2018 and 2017 , 35% and 33% , respectively, of our repurchase agreement funding was sourced through our wholly-owned captive broker-dealer subsidiary, Bethesda Securities, LLC ("BES"). Amounts sourced through BES include funding from the General Collateral Finance Repo service ("GCF Repo") offered by the Fixed Income Clearing Corporation ("FICC"), which totaled 33% and 30% of our repurchase agreement funding outstanding as of December 31, 2018 and 2017 , respectively. Reverse Repurchase Agreements As of December 31, 2018 and 2017 , we had $21.8 billion and $11.0 billion , respectively, of reverse repurchase agreements outstanding used primarily to borrow securities to cover short sales of U.S. Treasury securities, for which we had associated obligations to return borrowed securities at fair value of $21.4 billion and $10.5 billion , respectively. As of December 31, 2018 and 2017 , $4.5 billion and $2.7 billion , respectively, of our reverse repurchase agreements were with the FICC sourced through BES.

Derivative and Other Hedging In

Derivative and Other Hedging Instruments	12 Months Ended
	Dec. 31, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
US Government Futures Securities [Table Text Block]	U.S. Treasury Futures December 31, 2018 December 31, 2017 Maturity Notional Amount - Long (Short) Cost Basis Fair Value Net Carrying Value 1 Notional Amount - Long (Short) Cost Basis Fair Value Net Carrying Value 1 5 years $ — $ — $ — $ — $ (730 ) $ (852 ) $ (848 ) $ 4 10 years (1,650 ) (1,969 ) (2,013 ) (44 ) (2,180 ) (2,718 ) (2,703 ) 15 Total U.S. Treasury futures $ (1,650 ) $ (1,969 ) $ (2,013 ) $ (44 ) $ (2,910 ) $ (3,570 ) $ (3,551 ) $ 19 ________________________________ 1. Net carrying value represents the difference between the fair market value and the cost basis (or the forward price to be paid/(received) for the underlying U.S. Treasury security) of the U.S. Treasury futures contract as of period-end and is reported in derivative assets/(liabilities), at fair value in our consolidated balance sheets.
Derivative and Other Hedging Instruments	Derivative and Other Hedging Instruments We hedge a portion of our interest rate risk by entering into interest rate swaps, interest rate swaptions and U.S. Treasury securities and U.S. Treasury futures contracts, primarily through short sales. We may also utilize TBA securities, options and other types of derivative instruments to hedge a portion of our risk. 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 . Derivative and Other Hedging Instrument Assets (Liabilities), at Fair Value The table below summarizes fair value information about our derivative and other hedging instrument assets/(liabilities) as of December 31, 2018 and 2017 (in millions): December 31, Derivative and Other Hedging Instruments Balance Sheet Location 2018 2017 Interest rate swaps Derivative assets, at fair value $ 126 $ 81 Swaptions Derivative assets, at fair value 37 75 TBA securities Derivative assets, at fair value 110 30 U.S. Treasury futures - short Derivative assets, at fair value — 19 Total derivative assets, at fair value $ 273 $ 205 Interest rate swaps Derivative liabilities, at fair value $ — $ (1 ) TBA securities Derivative liabilities, at fair value (40 ) (27 ) U.S. Treasury futures - short Derivative liabilities, at fair value (44 ) — Total derivative liabilities, at fair value $ (84 ) $ (28 ) U.S. Treasury securities - long U.S. Treasury securities, at fair value $ 46 $ — U.S. Treasury securities - short Obligation to return securities borrowed under reverse repurchase agreements, at fair value (21,431 ) (10,467 ) Total U.S. Treasury securities, net at fair value $ (21,385 ) $ (10,467 ) The following tables summarize certain characteristics of our derivative and other hedging instruments outstanding as of December 31, 2018 and 2017 (dollars in millions): December 31, 2018 December 31, 2017 Interest Rate Swaps Notional 1 Average Rate 2 Average Average Notional 1 Average Rate 2 Average Average ≤ 3 years $ 19,900 1.63% 2.62% 1.3 $ 21,025 1.40% 1.46% 1.5 > 3 to ≤ 5 years 8,425 2.06% 2.61% 4.0 6,825 1.82% 1.43% 4.1 > 5 to ≤ 7 years 7,875 2.66% 2.66% 6.1 5,775 2.02% 1.44% 5.9 > 7 to ≤ 10 years 10,550 2.36% 2.64% 8.8 6,650 2.10% 1.42% 9.1 > 10 years 4,875 2.77% 2.63% 11.6 3,425 2.49% 1.45% 12.9 Total $ 51,625 2.11% 2.63% 5.0 $ 43,700 1.74% 1.44% 4.5 ________________________________ 1. As of December 31, 2018 and 2017 , notional amount includes forward starting swaps of $5.7 billion and $4.6 billion , respectively, with an average forward start date of 0.5 and 0.3 years, respectively. 2. Average fixed pay rate includes forward starting swaps. Excluding forward starting swaps, the average fixed pay rate was 1.98% and 1.68% as of December 31, 2018 and 2017 , respectively. Swaptions Option Underlying Payer Swap Current Option Expiration Date Cost Basis Fair Value Average Months to Current Option Expiration Date 1 Notional Amount Average Fixed Pay Rate Average Receive Rate (LIBOR) Average Term (Years) December 31, 2018 ≤ 1 year $ 80 $ 23 4 $ 3,000 2.96% 3M 7.0 > 1 year ≤ 2 years 18 14 18 500 2.78% 3M 10.0 Total $ 98 $ 37 6 $ 3,500 2.93% 3M 7.4 December 31, 2017 ≤ 1 year $ 118 $ 46 7 $ 5,100 2.71% 3M 8.8 > 1 year ≤ 2 years 23 16 18 1,050 2.71% 3M 8.7 > 2 year ≤ 3 years 18 13 30 500 2.78% 3M 10.0 Total $ 159 $ 75 10 $ 6,650 2.72% 3M 8.9 ________________________________ 1. As of December 31, 2018 and 2017 , ≤ 1 year notional amount includes $700 million of Bermudan swaptions where the options may be exercised on predetermined dates up to their final exercise date, which is six months prior to the underlying swaps' maturity date. U.S. Treasury Securities December 31, 2018 December 31, 2017 Maturity Face Amount (Short) Cost Basis 1 Fair Value Face Amount (Short) Cost Basis 1 Fair Value 5 years $ (703 ) $ (706 ) $ (713 ) $ (288 ) $ (286 ) $ (283 ) 7 years (14,357 ) (14,325 ) (14,410 ) (6,131 ) (6,106 ) (6,029 ) 10 years (6,240 ) (6,224 ) (6,262 ) (4,280 ) (4,230 ) (4,155 ) Total U.S. Treasury securities $ (21,300 ) $ (21,255 ) $ (21,385 ) $ (10,699 ) $ (10,622 ) $ (10,467 ) ________________________________ 1. As of December 31, 2018 and 2017 , U.S. Treasury securities had a weighted average yield of 2.66% and 2.12% , respectively. U.S. Treasury Futures December 31, 2018 December 31, 2017 Maturity Notional Amount - Long (Short) Cost Basis Fair Value Net Carrying Value 1 Notional Amount - Long (Short) Cost Basis Fair Value Net Carrying Value 1 5 years $ — $ — $ — $ — $ (730 ) $ (852 ) $ (848 ) $ 4 10 years (1,650 ) (1,969 ) (2,013 ) (44 ) (2,180 ) (2,718 ) (2,703 ) 15 Total U.S. Treasury futures $ (1,650 ) $ (1,969 ) $ (2,013 ) $ (44 ) $ (2,910 ) $ (3,570 ) $ (3,551 ) $ 19 ________________________________ 1. Net carrying value represents the difference between the fair market value and the cost basis (or the forward price to be paid/(received) for the underlying U.S. Treasury security) of the U.S. Treasury futures contract as of period-end and is reported in derivative assets/(liabilities), at fair value in our consolidated balance sheets. December 31, 2018 December 31, 2017 TBA Securities by Coupon Notional Amount - Long (Short) Cost Basis Fair Value Net Carrying Value 1 Notional Amount - Long (Short) Cost Basis Fair Value Net Carrying Value 1 15-Year TBA securities: 2.5% $ — $ — $ — $ — $ 1,373 $ 1,372 $ 1,370 $ (2 ) 3.0% 567 557 566 9 3,161 3,225 3,217 (8 ) 3.5% 1,706 1,708 1,726 18 414 428 428 — 4.0% 1,350 1,370 1,381 11 — — — — Total 15-Year TBA securities 3,623 3,635 3,673 38 4,948 5,025 5,015 (10 ) 30-Year TBA securities: 3.0% 1,028 981 1,003 22 4,317 4,303 4,312 9 3.5% (2,979 ) (2,943 ) (2,977 ) (34 ) 3,932 4,027 4,034 7 4.0% 3,030 3,073 3,089 16 2,338 2,449 2,446 (3 ) ≥ 4.5% 2,450 2,506 2,534 28 (61 ) (65 ) (65 ) — Total 30-Year TBA securities, net 3,529 3,617 3,649 32 10,526 10,714 10,727 13 Total TBA securities, net $ 7,152 $ 7,252 $ 7,322 $ 70 $ 15,474 $ 15,739 $ 15,742 $ 3 ________________________________ 1. Net carrying value represents the difference between the fair market value and the cost basis (or the forward price to be paid/(received) for the underlying Agency security) of the TBA contract as of period-end and is reported in derivative assets/(liabilities), at fair value in our consolidated balance sheets. Gain (Loss) From Derivative Instruments and Other Securities, Net The following table summarizes changes in our derivative and other hedge portfolio and their effect on our consolidated statements of comprehensive income for fiscal years 2018 , 2017 and 2016 (in millions): Derivative and Other Hedging Instruments Beginning Notional Amount Additions Settlement, Termination, Expiration or Exercise Ending Notional Amount Gain/(Loss) on Derivative Instruments and Other Securities, Net 1 Fiscal Year 2018: TBA securities, net $ 15,474 194,534 (202,856 ) $ 7,152 $ (299 ) Interest rate swaps $ 43,700 14,350 (6,425 ) $ 51,625 140 Payer swaptions $ 6,650 1,250 (4,400 ) $ 3,500 90 U.S. Treasury securities - short position $ (10,699 ) (19,278 ) 8,632 $ (21,345 ) (161 ) U.S. Treasury securities - long position $ — 1,949 (1,904 ) $ 45 1 U.S. Treasury futures contracts - short position $ (2,910 ) (7,859 ) 9,119 $ (1,650 ) 48 $ (181 ) Fiscal Year 2017: TBA securities, net $ 10,916 237,601 (233,043 ) $ 15,474 $ 330 Interest rate swaps $ 37,175 14,825 (8,300 ) $ 43,700 67 Payer swaptions $ 1,200 6,450 (1,000 ) $ 6,650 (66 ) U.S. Treasury securities - short position $ (8,061 ) (14,030 ) 11,392 $ (10,699 ) (141 ) U.S. Treasury securities - long position $ 189 404 (593 ) $ — 1 U.S. Treasury futures contracts - short position $ (1,810 ) (11,340 ) 10,240 $ (2,910 ) — $ 191 Fiscal Year 2016: TBA securities, net $ 7,295 116,439 (112,818 ) $ 10,916 $ (59 ) Interest rate swaps $ 40,525 15,650 (19,000 ) $ 37,175 (397 ) Payer swaptions $ 2,150 500 (1,450 ) $ 1,200 (3 ) U.S. Treasury securities - short position $ (1,714 ) (9,884 ) 3,537 $ (8,061 ) 7 U.S. Treasury securities - long position $ 25 961 (797 ) $ 189 134 U.S. Treasury futures contracts - short position $ (1,860 ) (7,840 ) 7,890 $ (1,810 ) (5 ) $ (323 ) ________________________________ 1. Amounts exclude other miscellaneous gains and losses recognized in gain (loss) on derivative instruments and other securities, net in our consolidated statements of comprehensive income.

Pledged Assets

Pledged Assets	12 Months Ended
	Dec. 31, 2018
Pledged Assets [Abstract]
Pledged Assets	30 and ≤ 60 days 14,586 14,810 46 12,950 13,061 38 > 60 and ≤ 90 days 7,770 7,843 24 4,000 4,013 11 > 90 days 6,882 7,079 21 15,385 15,512 45 Total $ 79,182 $ 80,386 $ 247 $ 52,497 $ 52,899 $ 153 ________________________________ 1. Includes $163 million and $182 million of retained interests in our consolidated VIEs pledged as collateral under repurchase agreements as of December 31, 2018 and 2017 , respectively. 2. December 31, 2018 amounts exclude $437 million of repledged U.S. Treasury securities received as collateral from counterparties. Assets Pledged from Counterparties As of December 31, 2018 and 2017 , we had assets pledged to us from counterparties as collateral under our reverse repurchase and derivative agreements summarized in the tables below (in millions). December 31, 2018 December 31, 2017 Assets Pledged to AGNC 1 Reverse Repurchase Agreements Derivative Agreements Repurchase Agreements Total Reverse Repurchase Agreements Derivative Agreements Repurchase Agreements Total U.S. Treasury securities - fair value $ 21,876 $ 35 $ 37 $ 21,948 $ 10,853 $ — $ — $ 10,853 Cash — 129 — 129 — 82 — 82 Total $ 21,876 $ 164 $ 37 $ 22,077 $ 10,853 $ 82 $ — $ 10,935 ________________________________ 1. Includes repledged collateral. U.S Treasury securities received as collateral under our reverse repurchase agreements for which we use to cover short sales of U.S. Treasury securities are accounted for as securities borrowing transactions. We recognize a corresponding obligation to return the borrowed securities at fair value on the accompanying consolidated balance sheets based on the value of the underlying borrowed securities as of the reporting date. Cash collateral received is recognized in cash and cash equivalents with a corresponding amount recognized in accounts payable and other accrued liabilities on the accompanying consolidated balance sheets. 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 master netting arrangements and can potentially be offset on our consolidated balance sheets as of December 31, 2018 and 2017 (in millions): Offsetting of Financial 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 in the Consolidated Balance Sheets Net Amount Financial Instruments Collateral Received 2 December 31, 2018 Interest rate swap and swaption agreements, at fair value 1 $ 163 $ — $ 163 $ — $ (158 ) $ 5 TBA securities, at fair value 110 — 110 (40 ) — 70 Receivable under reverse repurchase agreements 21,813 — 21,813 (17,236 ) (4,575 ) 2 Total $ 22,086 $ — $ 22,086 $ (17,276 ) $ (4,733 ) $ 77 December 31, 2017 Interest rate swap and swaption agreements, at fair value 1 $ 156 $ — $ 156 $ (1 ) $ (82 ) $ 73 TBA securities, at fair value 30 — 30 (22 ) — 8 Receivable under reverse repurchase agreements 10,961 — 10,961 (9,682 ) (1,279 ) — Total $ 11,147 $ — $ 11,147 $ (9,705 ) $ (1,361 ) $ 81 Offsetting of Financial 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 in the Consolidated Balance Sheets Net Amount Financial Instruments Collateral Pledged 2 December 31, 2018 Interest rate swap agreements, at fair value 1 $ — $ — $ — $ — $ — $ — TBA securities, at fair value 40 — 40 (40 ) — — Repurchase agreements 75,717 — 75,717 (17,236 ) (58,481 ) — Total $ 75,757 $ — $ 75,757 $ (17,276 ) $ (58,481 ) $ — December 31, 2017 Interest rate swap agreements, at fair value 1 $ 1 $ — $ 1 $ (1 ) $ — $ — TBA securities, at fair value 27 — 27 (22 ) (5 ) — Repurchase agreements and FHLB advances 50,296 — 50,296 (9,682 ) (40,614 ) — Total $ 50,324 $ — $ 50,324 $ (9,705 ) $ (40,619 ) $ — ________________________________ 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 pledged / received as collateral, at fair value. Amounts include repledged collateral. Amounts presented are limited to collateral pledged sufficient to reduce the net amount to zero for individual counterparties, as applicable." id="sjs-B4">Pledged Assets Our funding agreements require us to fully collateralize our obligations under the agreements based upon our counterparties' collateral requirements and their determination of the fair value of the securities pledged as collateral, which fluctuates with changes in interest rates, credit quality and liquidity conditions within the investment banking, mortgage finance and real estate industries. Our derivative contracts similarly require us to fully collateralize our obligations under such agreements, which will vary over time based on similar factors as well as our counterparties' determination of the value of the derivative contract. We are typically required to post initial margin upon execution of derivative transactions, such as under our interest rate swap agreements and TBA contracts, and subsequently post or receive variation margin based on daily fluctuations in fair value. Our prime brokerage agreements, pursuant to which we receive custody and settlement services, and the clearing organizations utilized by our wholly-owned captive broker-dealer subsidiary, Bethesda Securities, LLC, also require that we post minimum daily clearing deposits. If we breach our collateral requirements, we will be required to fully settle our obligations under the agreements, which could include a forced liquidation of our pledged collateral. Our counterparties also apply a "haircut" to our pledged collateral, which means our collateral is valued at slightly less than market value and limits the amount we can borrow against our securities. This haircut reflects the underlying risk of the specific collateral and protects our counterparty against a change in its value. Our agreements do not specify the haircut; rather haircuts are determined on an individual transaction basis. Consequently, our funding agreements and derivative contracts expose us to credit risk relating to potential losses that could be recognized if our counterparties fail to perform their obligations under such agreements. We minimize this risk by limiting our counterparties to major financial institutions with acceptable credit ratings or to registered clearinghouses and U.S. government agencies, and we monitor our positions with individual counterparties. In the event of a default by a counterparty, we may have difficulty obtaining our assets pledged as collateral to such counterparty and may not receive payments provided for under the terms of our derivative agreements. In the case of centrally cleared instruments, 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 clearing exchanges' initial and daily mark-to-market margin requirements, clearinghouse guarantee funds and other resources that are available in the event of a clearing member default. As of December 31, 2018 , our maximum amount at risk with any counterparty other than the Fixed Income Clearing Corporation related to our repurchase agreements was less than 4% of our tangible stockholders' equity. As of December 31, 2018 , approximately 8% of our tangible stockholder's equity was at risk with the Fixed Income Clearing Corporation. Equity at risk is defined as the net carrying value of securities pledged under repurchase agreements, including accrued interest plus any cash or assets on deposit to secure the repurchase obligation, less the amount of the repurchase liability, including accrued interest. Our International Swaps and Derivatives Association ("ISDA") Master Agreements contain a cross default provision under which a default under the terms of certain of our other indebtedness in excess of certain thresholds causes an event of default under the ISDA Master Agreement. Threshold amounts vary by lender. Following an event of default, we could be required to settle our obligations under the agreements. Additionally, under certain of our ISDA Master Agreements, we could be required to settle our obligations under the agreements 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 up to certain specified levels. As of December 31, 2018 , 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 financial statements. Assets Pledged to Counterparties The following tables summarize our assets pledged as collateral under our funding, derivative and prime broker agreements by type, including securities pledged related to securities sold but not yet settled, as of December 31, 2018 and 2017 (in millions): December 31, 2018 Assets Pledged to Counterparties 1 Repurchase Agreements 2 Debt of Consolidated VIEs Derivative Agreements Prime Broker Agreements 3 Total Agency RMBS - fair value $ 78,997 $ 436 $ 174 $ 133 $ 79,740 CRT - fair value 141 — — — 141 Non-Agency - fair value 45 — — — 45 U.S. Treasury securities - fair value 437 — — — 437 Accrued interest on pledged securities 246 1 1 — 248 Restricted cash and cash equivalents 77 — 522 — 599 Total $ 79,943 $ 437 $ 697 $ 133 $ 81,210 December 31, 2017 Assets Pledged to Counterparties 1 Repurchase Agreements 2 Debt of Consolidated VIEs Derivative Agreements Prime Broker Agreements 3 Total Agency RMBS - fair value $ 52,497 $ 662 $ 221 $ 519 $ 53,899 U.S. Treasury securities - fair value 113 — 72 — 185 Accrued interest on pledged securities 153 2 1 2 158 Restricted cash and cash equivalents 35 — 281 1 317 Total $ 52,798 $ 664 $ 575 $ 522 $ 54,559 ________________________________ 1. Includes repledged assets received as collateral from counterparties. 2. Includes $163 million and $182 million of retained interests in our consolidated VIEs pledged as collateral under repurchase agreements as of December 31, 2018 and 2017 , respectively. 3. Includes margin for TBAs cleared through prime brokers and other clearing deposits. Securities transferred to our consolidated VIEs can only be used to settle the obligations of each respective VIE. However, we may pledge our retained interests in our consolidated VIEs as collateral under our repurchase agreements and derivative contracts. Please refer to Note 3 for additional information regarding our consolidated VIEs. The following table summarizes our securities pledged as collateral under our repurchase agreements by the remaining maturity of our borrowings, including securities pledged related to sold but not yet settled securities, as of December 31, 2018 and 2017 (in millions). For the corresponding borrowings associated with the following amounts and the interest rates thereon, refer to Note 4 . December 31, 2018 December 31, 2017 Securities Pledged by Remaining Maturity of Repurchase Agreements 1,2 Fair Value of Pledged Securities Amortized Cost of Pledged Securities Accrued Interest on Pledged Securities Fair Value of Pledged Securities Amortized Cost of Pledged Securities Accrued Interest on Pledged Securities ≤ 30 days $ 49,944 $ 50,654 $ 156 $ 20,162 $ 20,313 $ 59 > 30 and ≤ 60 days 14,586 14,810 46 12,950 13,061 38 > 60 and ≤ 90 days 7,770 7,843 24 4,000 4,013 11 > 90 days 6,882 7,079 21 15,385 15,512 45 Total $ 79,182 $ 80,386 $ 247 $ 52,497 $ 52,899 $ 153 ________________________________ 1. Includes $163 million and $182 million of retained interests in our consolidated VIEs pledged as collateral under repurchase agreements as of December 31, 2018 and 2017 , respectively. 2. December 31, 2018 amounts exclude $437 million of repledged U.S. Treasury securities received as collateral from counterparties. Assets Pledged from Counterparties As of December 31, 2018 and 2017 , we had assets pledged to us from counterparties as collateral under our reverse repurchase and derivative agreements summarized in the tables below (in millions). December 31, 2018 December 31, 2017 Assets Pledged to AGNC 1 Reverse Repurchase Agreements Derivative Agreements Repurchase Agreements Total Reverse Repurchase Agreements Derivative Agreements Repurchase Agreements Total U.S. Treasury securities - fair value $ 21,876 $ 35 $ 37 $ 21,948 $ 10,853 $ — $ — $ 10,853 Cash — 129 — 129 — 82 — 82 Total $ 21,876 $ 164 $ 37 $ 22,077 $ 10,853 $ 82 $ — $ 10,935 ________________________________ 1. Includes repledged collateral. U.S Treasury securities received as collateral under our reverse repurchase agreements for which we use to cover short sales of U.S. Treasury securities are accounted for as securities borrowing transactions. We recognize a corresponding obligation to return the borrowed securities at fair value on the accompanying consolidated balance sheets based on the value of the underlying borrowed securities as of the reporting date. Cash collateral received is recognized in cash and cash equivalents with a corresponding amount recognized in accounts payable and other accrued liabilities on the accompanying consolidated balance sheets. 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 master netting arrangements and can potentially be offset on our consolidated balance sheets as of December 31, 2018 and 2017 (in millions): Offsetting of Financial 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 in the Consolidated Balance Sheets Net Amount Financial Instruments Collateral Received 2 December 31, 2018 Interest rate swap and swaption agreements, at fair value 1 $ 163 $ — $ 163 $ — $ (158 ) $ 5 TBA securities, at fair value 110 — 110 (40 ) — 70 Receivable under reverse repurchase agreements 21,813 — 21,813 (17,236 ) (4,575 ) 2 Total $ 22,086 $ — $ 22,086 $ (17,276 ) $ (4,733 ) $ 77 December 31, 2017 Interest rate swap and swaption agreements, at fair value 1 $ 156 $ — $ 156 $ (1 ) $ (82 ) $ 73 TBA securities, at fair value 30 — 30 (22 ) — 8 Receivable under reverse repurchase agreements 10,961 — 10,961 (9,682 ) (1,279 ) — Total $ 11,147 $ — $ 11,147 $ (9,705 ) $ (1,361 ) $ 81 Offsetting of Financial 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 in the Consolidated Balance Sheets Net Amount Financial Instruments Collateral Pledged 2 December 31, 2018 Interest rate swap agreements, at fair value 1 $ — $ — $ — $ — $ — $ — TBA securities, at fair value 40 — 40 (40 ) — — Repurchase agreements 75,717 — 75,717 (17,236 ) (58,481 ) — Total $ 75,757 $ — $ 75,757 $ (17,276 ) $ (58,481 ) $ — December 31, 2017 Interest rate swap agreements, at fair value 1 $ 1 $ — $ 1 $ (1 ) $ — $ — TBA securities, at fair value 27 — 27 (22 ) (5 ) — Repurchase agreements and FHLB advances 50,296 — 50,296 (9,682 ) (40,614 ) — Total $ 50,324 $ — $ 50,324 $ (9,705 ) $ (40,619 ) $ — ________________________________ 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 pledged / received as collateral, at fair value. Amounts include repledged collateral. Amounts presented are limited to collateral pledged sufficient to reduce the net amount to zero for individual counterparties, as applicable.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements We determine the fair value of our financial instruments based on our estimate of the price that would be received to sell the asset or paid to transfer the liability in an orderly transaction between market participants at the measurement date. We typically obtain price estimates from multiple third-party pricing services and dealers or, if applicable, the clearing exchange (see Note 2 for further details.) We utilize a three-level valuation hierarchy for disclosure of fair value measurements. 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. The three levels of valuation 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 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 loss severities, 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. We also review third-party price estimates and perform procedures to validate their reasonableness, including an analysis of the range of estimates for each position, comparison to recent trade activity for similar securities, and for consistency with market conditions observed as of the measurement date. While we do not adjust prices we obtain from pricing sources, we will exclude prices for securities from our estimation of fair value if we determine (based on our validation procedures and our market knowledge and expertise) that the price is significantly different from what 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 categorization. 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, 2018 and 2017 based on their categorization within the valuation hierarchy (in millions). There were no transfers between valuation hierarchy levels during the periods presented. December 31, 2018 December 31, 2017 Level 1 Level 2 Level 3 Level 1 Level 2 Level 3 Assets: Agency securities $ — $ 82,291 $ — $ — $ 55,506 $ — Agency securities transferred to consolidated VIEs — 436 — — 662 — Credit risk transfer securities — 1,012 — — 876 — Non-Agency securities — 548 — — 36 — U.S. Treasury securities 46 — — — — — REIT equity securities — — — 29 — — Interest rate swaps — 126 — — 81 — Swaptions — 37 — — 75 — TBA securities — 110 — — 30 — U.S. Treasury futures — — — 19 — — Total $ 46 $ 84,560 $ — $ 48 $ 57,266 $ — Liabilities: Debt of consolidated VIEs $ — $ 275 $ — $ — $ 357 $ — Obligation to return U.S. Treasury securities borrowed under reverse repurchase agreements 21,431 — — 10,467 — — Interest rate swaps — — — — 1 — TBA securities — 40 — — 27 — U.S. Treasury futures (44 ) — — — — — Total $ 21,387 $ 315 $ — $ 10,467 $ 385 $ — Excluded from the table above are financial instruments, including cash and cash equivalents, restricted cash and cash equivalents, receivables, payables and borrowings under repurchase agreements, which are presented in our consolidated financial statements at cost. The cost basis of these instruments is determined to approximate fair value due to their short duration or, in the case of longer-term repo, due to floating rates of interest based on an index plus or minus a fixed spread which is consistent with fixed spreads demanded in the market. We estimate the fair value of these instruments using "Level 1" or "Level 2" inputs.

Net Income (Loss) Per Common Sh

Net Income (Loss) Per Common Share (Notes)	12 Months Ended
	Dec. 31, 2018
Net Income (Loss) Per Common Share [Abstract]
Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]	Fiscal Year 2018 2017 2016 Weighted average number of common shares outstanding - basic 441.1 358.6 331.9 Unvested restricted stock units and performance share units 0.3 0.1 — Weighted average number of common shares outstanding - diluted 441.4 358.7 331.9 Net income available to common stockholders $ 93 $ 733 $ 595 Net income per common share - basic $ 0.21 $ 2.04 $ 1.79 Net income per common share - diluted $ 0.21 $ 2.04 $ 1.79
Earnings Per Share [Text Block]	Net Income Per Common Share Basic net income per common share includes no dilution and is computed by dividing net income applicable to common stock by the weighted-average number of common shares outstanding for the respective period. Diluted earnings per common share includes the impact of dilutive potential common shares outstanding during the period using the treasury stock method. Dilutive potential common shares outstanding include unvested restricted stock units and performance share units granted under our long-term incentive program to employees and non-employee Board of Directors. The following table presents the computations of basic and diluted net income per common share for the periods indicated (shares and dollars in millions): Fiscal Year 2018 2017 2016 Weighted average number of common shares outstanding - basic 441.1 358.6 331.9 Unvested restricted stock units and performance share units 0.3 0.1 — Weighted average number of common shares outstanding - diluted 441.4 358.7 331.9 Net income available to common stockholders $ 93 $ 733 $ 595 Net income per common share - basic $ 0.21 $ 2.04 $ 1.79 Net income per common share - diluted $ 0.21 $ 2.04 $ 1.79

Stockholders' Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2018
Equity [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 10.0 million shares of preferred stock in one or more classes or series. As of December 31, 2017 and December 31, 2018 , 8,050 shares were designated as 7.750% Series B Cumulative Redeemable Preferred Stock ("Series B Preferred Stock") and 13,800 shares were designated as 7.00% Series C Fixed-to-Floating Rate Cumulative Redeemable Preferred Stock ("Series C Preferred Stock"). Shares of Series B and Series C Preferred Stock are represented by depositary shares equal to 1/1000 interest in each share of Series B and Series C Preferred Stock, respectively. As of December 31, 2017 and December 31, 2018 , we had 7,000 shares of Series B Preferred Stock and 13,000 shares of Series C Preferred Stock outstanding (represented by 7.0 million Series B depositary shares and 13.0 million Series C depositary shares outstanding, respectively) and 9,980,000 of authorized but unissued shares of preferred stock. Holders of depository shares underlying our Series B Preferred Stock are entitled to receive cumulative cash dividends at a rate of 7.750% per annum of their $25.00 per depositary share liquidation preference. Holders of depositary shares underlying our Series C Preferred Stock are entitled to receive cumulative cash dividends at a rate of 7.00% per annum up to, and including, October 14, 2022 and thereafter at a floating rate equal to three-month LIBOR plus a spread of 5.111% per annum of their $25.00 per depositary share liquidation preference. Dividends are payable quarterly in arrears on the 15th day of each January, April, July and October. As of December 31, 2018 , we had declared all required quarterly dividends on our preferred stock. Our preferred stock ranks senior to our common stock with respect to the payment of dividends and the distribution of assets upon a voluntary or involuntary liquidation, dissolution or winding up of the Company. Our preferred stock has no stated maturity, is not subject to any sinking fund or mandatory redemption and ranks on parity with each other. Under certain circumstances upon a change of control, our preferred stock is convertible to shares of our common stock. Holders of our preferred stock and depository shares underlying our preferred stock have no voting rights, except under limited conditions. Beginning on May 8, 2019 and October 15, 2022, depository shares underlying our Series B and Series C Preferred Stock, respectively, will be redeemable at $25.00 per depositary share, plus accumulated and unpaid dividends (whether or not declared) exclusively at our option. We may redeem shares of our preferred stock prior to our optional redemption date under certain circumstances intended to preserve our qualification as a REIT for U.S federal income tax purposes. In September 2017, we redeemed all of our issued and outstanding shares of Series A Preferred Stock for $173 million (or $25 per share liquidation preference), plus accrued and unpaid dividends, and, in October 2017, we filed a Certificate of Elimination of our Series A Preferred Stock with the Secretary of State of the State of Delaware, which eliminated the designation of Series A Preferred Stock from our amended and restated certificate of incorporation. Prior to the September 2017 redemption, holders of Series A Preferred Stock were entitled to receive cumulative cash dividends at a rate of 8.000% per annum of their $25.00 per share liquidation preference. Common Stock Offerings During fiscal years 2018 and 2017, we completed follow-on public offerings of our common stock summarized in the table below (in millions, except for per share data). During fiscal year 2016, we did not complete any follow-on public offerings. Follow-On Public Offering Price Received Per Share, Net Shares Net Proceeds Fiscal Year 2018: May 2018 $18.35 34.5 $ 633 August 2018 $18.68 43.7 817 November 2018 $17.09 46.0 786 Total fiscal year 2018 124.2 $ 2,236 Fiscal Year 2017: May 2017 $20.51 24.5 $ 503 September 2017 $20.47 28.2 577 Total fiscal year 2017 52.7 $ 1,080 At-the-Market Offering Program We have entered into 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 up to a maximum aggregate offering price of our common stock. On June 14, 2018, our existing sales agreement terminated, and we entered into new sales agreements for shares of our common stock having an aggregate offering price of up to $1 billion . The table below summarizes sales our common stock under the sales agreements during fiscal years 2018 and 2017 (in millions, except for per share data). During fiscal year 2016, we did not sell shares of our common stock under the sales agreements. As of December 31, 2018 , shares of our common stock with an aggregate offering price of $660 million remained available for issuance under this program. ATM Offerings Average Price Received Per Share, Net Shares Net Proceeds Fiscal Year 2018 $18.03 20.8 $ 375 Fiscal Year 2017 $20.96 7.6 $ 159 Common Stock Repurchase Program From time-to-time we are authorized by our Board of Directors to repurchase shares of our common stock under certain conditions. During fiscal year 2016, we repurchased 6.5 million shares of our common stock at an average repurchase price of $17.89 per share, including expenses, totaling $116 million . We did not repurchase shares of our common stock during fiscal year 2017 or 2018, and our most recent stock repurchase authorization expired on December 31, 2017. Distributions to Stockholders The following table summarizes cash dividends declared for fiscal years 2018, 2017 and 2016 (in millions, except per share amounts): Dividends Declared Dividends Declared Per Share 8.000 % Series A Cumulative Redeemable Preferred Stock Fiscal year 2017 $ 9 $ 1.333000 Fiscal year 2016 $ 14 $ 2.000000 7.750% Series B Cumulative Redeemable Preferred Stock (Per Depositary Share) Fiscal year 2018 $ 14 $ 1.937500 Fiscal year 2017 $ 14 $ 1.937500 Fiscal year 2016 $ 14 $ 1.937500 7.00% Series C Fixed-to-Floating Rate Cumulative Redeemable Preferred Stock (Per Depositary Share) Fiscal year 2018 $ 23 $ 1.750000 Fiscal year 2017 $ 9 $ 0.695140 Common Stock Fiscal year 2018 $ 964 $ 2.160000 Fiscal year 2017 $ 777 $ 2.160000 Fiscal year 2016 $ 763 $ 2.300000 Accumulated Other Comprehensive Income (Loss) The following table summarizes changes to accumulated OCI for fiscal years 2018 , 2017 and 2016 (in millions): Fiscal Year Accumulated Other Comprehensive Income (Loss) 2018 2017 2016 Beginning Balance $ (345 ) $ (397 ) $ (66 ) OCI before reclassifications (677 ) (31 ) (261 ) (Gain) loss amounts for available-for-sale securities reclassified from accumulated OCI to realized gain (loss) on sale of investment securities 79 83 (109 ) Periodic interest costs of interest rate swaps previously designated as hedges under GAAP, net — — 39 Ending Balance $ (943 ) $ (345 ) $ (397 )

Equity Incentive Plan (Notes)

Equity Incentive Plan (Notes)	12 Months Ended
	Dec. 31, 2018
Director Plan [Abstract]
Disclosure of Compensation Related Costs, Share-based Payments [Text Block]	Long-Term Incentive Compensation Stock-Based Incentive Plans Under our 2016 Equity and Incentive Compensation Plan (the "2016 Equity Plan"), we may grant equity-based compensation in the form of stock options, stock appreciation rights, restricted shares, RSUs, performance shares, PSUs, dividend equivalents and certain other awards denominated or payable in, or otherwise based on, shares of our common stock, plus cash incentive awards, for the purpose of providing our non-employee directors, officers and other employees incentives and rewards for service or performance. The 2016 Equity Plan authorizes a total of 10 million shares our common stock that may be used to satisfy awards under the plan, subject to the share counting rules set forth within the plan. The Compensation Committee of our Board of Directors determines awards to be granted under our 2016 Equity Plan and the terms of such awards. Prior to establishing our 2016 Equity Plan, we granted equity-based awards to independent directors per the terms of our AGNC Equity Incentive Plan for Independent Directors (the "Director Plan"). The Director Plan was terminated in December of 2016 and replaced by our 2016 Equity Plan. Outstanding awards under the Director Plan continued in effect in accordance with their terms. During fiscal years 2018, 2017 and 2016, we granted RSU awards to employees with a grant date fair value of $4 million , $4 million and $2 million , respectively, which vest annually over a three-year period. Additionally, during fiscal year 2018, we granted fully vested RSU awards to employees with a grant date fair value of $4 million in exchange for satisfaction and conversion of AGNC's obligations of an equivalent value under outstanding long-term incentive compensation awards granted to employees under the MTGE Incentive Plan ("RSU Exchange Awards") (see Other Long-Term Incentive Compensation below). During fiscal years 2018, 2017 and 2016, we granted RSU awards to independent directors of $500,000 , $500,000 and $625,000 , respectively, which vest over a 12 to 13 month period. The following table summarizes RSU awards under our 2016 Equity Plan for fiscal years 2018, 2017 and 2016: 2016 Equity Incentive Plan RSU Awards Weighted Average Grant Date Fair Value 1 Weighted Average Vest Date Fair Value Unvested balance as of December 31, 2015 — $ — $ — Granted 101,407 $ 17.89 $ — Accrued RSU dividend equivalents 968 $ — $ — Unvested balance as of December 31, 2016 102,375 $ 17.72 $ — Granted 238,203 $ 19.52 $ — Accrued RSU dividend equivalents 32,498 $ — $ — Vested (37,602 ) $ 16.08 $ 20.42 Forfeitures (246 ) $ 18.29 $ — Unvested balance as of December 31, 2017 335,228 $ 17.46 $ — Granted 2 261,036 $ 18.05 $ — Accrued RSU dividend equivalents 56,618 $ — $ — Vested 2 (150,423 ) $ 16.52 $ 18.60 Forfeitures (546 ) $ 16.98 $ — Unvested balance as of December 31, 2018 501,913 $ 16.08 $ — ________________________________ 1. Accrued RSU award dividend equivalents have a weighted average grant date fair value of $0. 2. Excludes 185,285 of RSU Exchange Awards. The following table summarizes RSU and restricted stock transactions under the Director Plan for fiscal years 2017 and 2016: Director Plan Shares of Restricted Stock RSU Awards Weighted Average Grant Date Fair Value 1 Weighted Average Vest Date Fair Value Unvested balance as of December 31, 2015 5,000 31,431 $ 21.44 $ — Granted — 33,015 $ 18.93 $ — Accrued RSU dividend equivalents — 3,527 $ — $ — Vested (5,000 ) (46,538 ) $ 20.00 $ 18.99 Unvested balance as of December 31, 2016 — 21,435 $ 17.49 $ — Accrued RSU dividend equivalents — 1,032 $ — $ — Vested — (22,467 ) $ 16.69 $ 20.15 Unvested balance as of December 31, 2017 — — $ — $ — ________________________________ 1. Accrued RSU award dividend equivalents have a weighted average grant date fair value of $0. During fiscal years 2018 and 2017, we granted PSU awards to employees under our 2016 Equity Plan, which vest at the end of a three-year period provided that specified performance criteria are met. The performance criteria are based on a formula tied to our achievement of long-term economic returns consisting of the change in tangible net book value and dividends paid per common share on an absolute basis and relative to a select group of our peers. The fair value of the PSU awards granted during fiscal years 2018 and 2017 as of the grant date was $5 million and $5 million , respectively, assuming the target levels of performance are achieved, but the actual value will vary within a range of 0% to 200% of target based on actual performance achieved relative to the targets. The following table summarizes PSU awards under our 2016 Equity Plan for fiscal years 2018 and 2017. We did not issue PSU awards during fiscal year 2016. 2016 Equity Incentive Plan PSUs at Target Performance Level Weighted Average Grant Date Fair Value 1 Unvested balance as of December 31, 2016 — $ — Granted 250,609 $ 19.39 Accrued PSU dividend equivalents 22,767 $ — Vested — $ — Unvested balance as of December 31, 2017 273,376 $ 17.78 Granted 272,228 $ 17.98 Accrued PSU dividend equivalents 61,171 $ — Vested — $ — Unvested balance as of December 31, 2018 606,775 $ 16.08 _______________________ 1. Accrued PSU award dividend equivalents have a weighted average grant date fair value of $0. As of December 31, 2018 , 7.9 million shares remained available for awards under the 2016 Equity Plan. For purposes of determining the total number of shares available for awards under the 2016 Equity Plan, available shares are reduced by (i) shares issued for vested RSU awards, net of units withheld to cover minimum statutory tax withholding requirements paid by us in cash on behalf of the employee and (ii) outstanding unvested awards, (iii) outstanding previously vested awards, if distribution of such awards has been deferred beyond the vesting date ("deferred awards"), and (iv) accrued dividend equivalent units on outstanding awards through December 31, 2018 . Unvested performance-based awards assume the maximum payout under the terms of the award. As of December 31, 2018 , 0.3 million of deferred awards were outstanding. During fiscal years 2018, 2017 and 2016, we recognized compensation expense of $6.1 million , $3.1 million and $28 thousand , respectively, for stock-based awards to employees and we recognized other operating expense of $0.5 million , $0.5 million and $0.7 million , respectively, for stock-based awards to independent directors. As of December 31, 2018 , we had unrecognized expense related to stock-based awards of approximately $11 million , which is expected to be recognized over a weighted average period of 1.7 years. Other Long-Term Incentive Compensation During fiscal years 2018 and 2017, we granted long-term incentive compensation awards to employees under our MTGE Incentive Plan (the "Incentive Plan"), with original grant date fair values of $2 million and $2 million , respectively. Awards granted under the Incentive Plan were used to purchase shares of MTGE common stock on the open market and vested annually over a three-year period. Following the sale of MTGE and the resultant termination of the MTGE management agreement, all of the outstanding unvested awards under the Incentive Plan were fully vested (see Note 12). Deferred awards, or awards for which distribution of such awards had been deferred beyond the vesting date, were converted into AGNC RSU Exchange Awards of equal value under the 2016 Equity Plan. During fiscal years 2018 and 2017, we recognized long-term incentive compensation expense associated with awards under the Incentive Plan of $5 million and $1 million , respectively.
Schedule of Share-based Compensation, Restricted Stock Units Award Activity [Table Text Block]	The following table summarizes RSU awards under our 2016 Equity Plan for fiscal years 2018, 2017 and 2016: 2016 Equity Incentive Plan RSU Awards Weighted Average Grant Date Fair Value 1 Weighted Average Vest Date Fair Value Unvested balance as of December 31, 2015 — $ — $ — Granted 101,407 $ 17.89 $ — Accrued RSU dividend equivalents 968 $ — $ — Unvested balance as of December 31, 2016 102,375 $ 17.72 $ — Granted 238,203 $ 19.52 $ — Accrued RSU dividend equivalents 32,498 $ — $ — Vested (37,602 ) $ 16.08 $ 20.42 Forfeitures (246 ) $ 18.29 $ — Unvested balance as of December 31, 2017 335,228 $ 17.46 $ — Granted 2 261,036 $ 18.05 $ — Accrued RSU dividend equivalents 56,618 $ — $ — Vested 2 (150,423 ) $ 16.52 $ 18.60 Forfeitures (546 ) $ 16.98 $ — Unvested balance as of December 31, 2018 501,913 $ 16.08 $ — ________________________________ 1. Accrued RSU award dividend equivalents have a weighted average grant date fair value of $0. 2. Excludes 185,285 of RSU Exchange Awards.
Share-based Compensation, Performance Shares Award Outstanding Activity [Table Text Block]	2016 Equity Incentive Plan PSUs at Target Performance Level Weighted Average Grant Date Fair Value 1 Unvested balance as of December 31, 2016 — $ — Granted 250,609 $ 19.39 Accrued PSU dividend equivalents 22,767 $ — Vested — $ — Unvested balance as of December 31, 2017 273,376 $ 17.78 Granted 272,228 $ 17.98 Accrued PSU dividend equivalents 61,171 $ — Vested — $ — Unvested balance as of December 31, 2018 606,775 $ 16.08 _______________________ 1. Accrued PSU award dividend equivalents have a weighted average grant date fair value of $0.
Schedule of Share-based Compensation, Restricted Stock and Restricted Stock Units Activity [Table Text Block]	The following table summarizes RSU and restricted stock transactions under the Director Plan for fiscal years 2017 and 2016: Director Plan Shares of Restricted Stock RSU Awards Weighted Average Grant Date Fair Value 1 Weighted Average Vest Date Fair Value Unvested balance as of December 31, 2015 5,000 31,431 $ 21.44 $ — Granted — 33,015 $ 18.93 $ — Accrued RSU dividend equivalents — 3,527 $ — $ — Vested (5,000 ) (46,538 ) $ 20.00 $ 18.99 Unvested balance as of December 31, 2016 — 21,435 $ 17.49 $ — Accrued RSU dividend equivalents — 1,032 $ — $ — Vested — (22,467 ) $ 16.69 $ 20.15 Unvested balance as of December 31, 2017 — — $ — $ — ________________________________ 1. Accrued RSU award dividend equivalents have a weighted average grant date fair value of $0.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2018
Narrative [Abstract]
Income Tax Disclosure [Text Block]	Income Taxes As of December 31, 2018, we have distributed all of our estimated taxable income for fiscal year 2018. Accordingly, we do not expect to incur an income tax liability on our 2018 taxable income. For fiscal years 2017 and 2016, we distributed all of our taxable income within the time limits prescribed by the Internal Revenue Code. Accordingly, we did not incur an income tax liability on our taxable income for such periods. 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, 2018, 2017 and 2016. Our tax returns for tax years 2015 and forward are open to examination by the IRS. If we incur income tax related interest and penalties, our policy is to classify them as a component of provision for income taxes.

Management Agreement and Relate

Management Agreement and Related Party Transactions (Notes)	12 Months Ended
	Dec. 31, 2018
Narrative [Abstract]
Related Party Transactions Disclosure [Text Block]	Management Agreement and Related Party Transactions Prior to our acquisition of AMM on July 1, 2016, and our associated management internalization, we were externally managed. Under our management agreement we incurred a monthly management fee equal to one-twelfth of 1.25% of our month-end stockholders' equity, adjusted to exclude the effect of any unrealized gains or losses included in either retained earnings or accumulated OCI. For fiscal year 2016, prior to our internalization, our management fee expense totaled $52 million . Through our acquisition of AMM we also became the external manager of MTGE. During fiscal years 2018, 2017 and 2016, we earned monthly management fee income totaling $12 million , $16 million and $8 million , respectively. During September 2018, MTGE completed a sale of the company to a third party. Coincident with the sale, we were paid a one-time termination fee under the management agreement of $42 million , which is reported in management fee income in our consolidated statements of comprehensive income for fiscal year 2018. Concurrent with the termination of the management agreement, we wrote-off our remaining unamortized intangible asset balance associated with the management agreement of $23 million , which is reported in other operating expense for fiscal year 2018.

Quarterly Results Quarterly Res

Quarterly Results Quarterly Results (Notes)	12 Months Ended
	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Quarterly Results	Quarterly Results (Unaudited) The following is a presentation of the quarterly results of operations and comprehensive income for fiscal years 2018 and 2017 (in millions, except per share data). Quarter Ended March 31, 2018 June 30, 2018 September 30, 2018 December 31, 2018 Interest income: Interest income $ 431 $ 414 $ 500 $ 604 Interest expense 206 237 312 418 Net interest income 225 177 188 186 Other gain (loss): Loss on sale of investment securities, net (2 ) (74 ) (40 ) (21 ) Unrealized gain (loss) on investment securities measured at fair value through net income, net (523 ) (94 ) (363 ) 683 Gain (loss) on derivative instruments and other securities, net 738 298 430 (1,633 ) Management fee income 4 4 46 — Total other gain (loss), net 217 134 73 (971 ) Expenses: Compensation and benefits 10 10 14 11 Other operating expenses 8 8 31 8 Total expenses 18 18 45 19 Net income (loss) 424 293 216 (804 ) Dividend on preferred stock 9 9 9 9 Net income (loss) available (attributable) to common shareholders $ 415 $ 284 $ 207 $ (813 ) Net income (loss) $ 424 $ 293 $ 216 $ (804 ) Unrealized gain (loss) on investment securities measured at fair value through other comprehensive income (loss), net (621 ) (145 ) (193 ) 361 Comprehensive income (loss) (197 ) 148 23 (443 ) Dividend on preferred stock 9 9 9 9 Comprehensive income (loss) available (attributable) to common shareholders $ (206 ) $ 139 $ 14 $ (452 ) Weighted average number of common shares outstanding - basic 391.3 404.9 462.3 504.2 Weighted average number of common shares outstanding - diluted 391.5 405.2 462.7 504.2 Net income (loss) per common share - basic and diluted $ 1.06 $ 0.70 $ 0.45 $ (1.61 ) Comprehensive income (loss) per common share - basic and diluted $ (0.53 ) $ 0.34 $ 0.03 $ (0.90 ) Dividends declared per common share $ 0.54 $ 0.54 $ 0.54 $ 0.54 Quarter Ended March 31, June 30, 2017 September 30, December 31, 2017 Interest income: Interest income $ 296 $ 293 $ 318 $ 386 Interest expense 98 112 140 174 Net interest income 198 181 178 212 Other gain (loss): Gain (loss) on sale of investment securities, net (84 ) 15 22 (16 ) Unrealized gain (loss) on investment securities measured at fair value through net income, net 16 9 (31 ) (65 ) Gain (loss) on derivative instruments and other securities, net (40 ) (169 ) 131 271 Management fee income 4 4 4 4 Total other gain (loss), net (104 ) (141 ) 126 194 Expenses: Compensation and benefits 10 10 10 12 Other operating expenses 8 6 8 9 Total expenses 18 16 18 21 Net income 76 24 286 385 Dividend on preferred stock 7 7 9 9 Issuance costs of redeemed preferred stock — — 6 — Net income available to common shareholders $ 69 $ 17 $ 271 $ 376 Net income $ 76 $ 24 $ 286 $ 385 Unrealized gain (loss) on investment securities measured at fair value through other comprehensive income (loss), net 46 121 90 (205 ) Comprehensive income 122 145 376 180 Dividend on preferred stock 7 7 9 9 Issuance costs of redeemed preferred stock — — 6 — Comprehensive income available to common shareholders $ 115 $ 138 $ 361 $ 171 Weighted average number of common shares outstanding - basic 331.0 346.4 364.7 391.3 Weighted average number of common shares outstanding - diluted 331.1 346.5 364.9 391.5 Net income per common share - basic and diluted $ 0.21 $ 0.05 $ 0.74 $ 0.96 Comprehensive income per common share - basic and diluted $ 0.35 $ 0.40 $ 0.99 $ 0.44 Dividends declared per common share $ 0.54 $ 0.54 $ 0.54 $ 0.54

Subsequent Event

Subsequent Event	12 Months Ended
	Dec. 31, 2018
Subsequent Events [Abstract]
Subsequent Event	Subsequent Events On January 10, 2019 and February 12, 2019, our Board of Directors declared a monthly dividend of $0.18 per common share, payable on February 11, 2019 and March 11, 2019, respectively, to common stockholders of record as of January 31, 2019 and February 28, 2019, respectively.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policy)	12 Months Ended
	Dec. 31, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Basis of Presentation and Significant Accounting Policies [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 all subsidiaries and variable interest entities for which we are the primary beneficiary. Significant intercompany accounts and transactions have been eliminated.
New Accounting Pronouncements and Changes in Accounting Principles [Text Block]	Adoption of Accounting Standard Updates As of January 1, 2018, we adopted Accounting Standards Update ("ASU") 2014-09, Revenue from Contracts with Customers (Topic 606), and ASU 2016-18 , Statement of Cash Flows (Topic 230) - Restricted Cash. The adoption of ASU 2014-09 resulted in reclassification of expense reimbursements from an other operating expense offset to management fee income on the consolidated statements of comprehensive income. Net income was not impacted. The adoption of ASU 2016-18 resulted in the presentation of restricted cash with cash and cash equivalents on the consolidated statements of cash flows when reconciling the total beginning and ending amounts. Our prior period results have been revised to conform to the current presentation.
Goodwill and Intangible Assets, Policy [Policy Text Block]	Goodwill and Other Intangible Asset, Net Goodwill is the cost of an acquisition in excess of the fair value of identified assets acquired and liabilities assumed and is recognized as an asset on our consolidated balance sheets. Acquired intangible assets that do not meet the criteria for recognition as a separate asset are included in goodwill. Goodwill is not subject to amortization but must be tested for impairment at least annually. Intangible assets meeting the criteria for recognition as separate assets are recorded at their respective fair market values at the date of acquisition. Intangible assets with an estimated useful life are amortized over their expected useful life. As of December 31, 2018 , we had $526 million of goodwill and, as of December 31, 2017, we had $526 million of goodwill and an intangible asset of $25 million associated with our management of MTGE Investment Corp. ("MTGE") (Nasdaq: MTGE) reported in goodwill and other intangible asset, net in our accompanying consolidated balance sheets related to our acquisition of AMM. We test goodwill for impairment on an annual basis and at interim periods when events or circumstances may make it more likely than not that an impairment has occurred. If a qualitative analysis indicates that there may be an impairment, a quantitative analysis is performed. The quantitative analysis requires that we compare the carrying value of the identified reporting unit comprising the goodwill to the reporting unit's fair value. If the reporting units' carrying value is greater than its fair value, an impairment charge is recognized to the extent the carrying amount of the reporting unit exceeds its fair value. During fiscal years 2018, 2017 or 2016, we did not recognize a goodwill impairment charge. During fiscal year 2018, we wrote-off the unamortized intangible asset balance due to the sale of MTGE to a third-party and corresponding termination of its management agreement (see Note 12).
Reverse Repurchase Agreements Policy [Policy Text Block]	Reverse Repurchase Agreements and Obligation to Return Securities Borrowed under Reverse Repurchase Agreements We borrow securities to cover short sales of U.S. Treasury securities through reverse repurchase transactions under our master repurchase agreements (see Derivative 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 typically have maturities of 30 days or less. The fair value of our reverse repurchase agreements is assumed to equal cost as the interest rates are considered to be at market.
New Accounting Pronouncements, Policy [Policy Text Block]	Recent Accounting Pronouncements We consider the applicability and impact of all ASUs issued by the Financial Accounting Standards Board. ASUs not listed below were determined to be either not applicable, are not expected to have a significant impact on our consolidated financial statements when adopted or did not have a significant impact on our consolidated financial statements upon adoption. ASU 2016-13, Financial Instruments - Credit Losses (Topic 326): ASU 2016-13 changes the impairment model for most financial assets and certain other instruments. Allowances for credit losses on available-for-sale debt securities will be recognized, rather than direct reductions in the amortized cost of the investments. The new model also requires the estimation of lifetime expected credit losses and corresponding recognition of allowance for losses on trade and other receivables, held-to-maturity debt securities, loans, and other instruments held at amortized cost. The ASU requires certain recurring disclosures and is effective for annual periods, and interim periods within those annual periods, beginning on or after December 15, 2019, with early adoption permitted for annual periods, and interim periods within those annual periods, beginning on or after December 15, 2018. ASU 2016-13 is not expected to have a significant impact on our consolidated financial statements. ASU 2016-2, Leases (Topic 842): ASU 2016-2 requires lessees to recognize virtually all their leases on the balance sheet by recording a right-of-use asset and a lease liability. The lease liability will be measured at the present value of lease payments and the right-of-use asset will be based on the lease liability value, subject to adjustments. Leases can be classified as either operating leases or finance leases. Operating leases will result in straight-line lease expense, while finance leases will result in front-loaded expense. This guidance is effective for the Company on January 1, 2019. We have evaluated ASU 2016-2 and determined that it will not have a significant impact on our consolidated financial statements.
Variable Interest Entity Disclosure [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. Prior to fiscal year 2016, we entered into transactions involving CMO trusts for which we determined we are the primary beneficiary given our level of control in the selection of Agency RMBS assets transferred to the CMO trust. Agency RMBS 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 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 the fair value of the Agency RMBS transferred to consolidated VIEs, less the fair value of our retained interests, which are measured on a market approach using "Level 2" inputs from third-party pricing services and dealer quotes. The fair value of the Agency RMBS transferred to the consolidated VIEs and the fair value of our retained interests are based on more observable inputs than inputs used to independently determine the value of our consolidated debt. As of December 31, 2018 and 2017 , debt of consolidated VIEs, at fair value, was $275 million and $357 million , respectively, had a weighted average interest rate of LIBOR plus 40 and 37 basis points, respectively, and an estimated weighted average life of 6.1 years and 5.7 years, respectively.
Share-based Compensation, Option and Incentive Plans Policy [Policy Text Block]	Stock-Based Compensation We measure and recognize compensation expense for all stock-based payment awards made to employees and independent directors based on their fair values. Stock-based awards issued under our equity incentive plan include time-based and performance-based restricted stock unit awards ("RSU" and "PSU" awards, respectively). An RSU and PSU awards are an agreement to issue an equivalent number of shares of our common stock, plus any equivalent shares for dividends declared on our common stock, at the time the award vests, or later if distribution of such shares has been deferred beyond the vesting date. RSU awards vest over a specified service period. PSU awards vest over a specified service period subject to achieving long-term performance criteria. We value RSU and PSU awards based on the fair value of our common stock on the date of grant. Compensation expense is recognized over each award’s respective service period. In the case of PSU awards, we estimate the probability that the performance criteria will be achieved and recognize expense only for those awards expected to vest. We reevaluate our estimates each reporting period and recognize a cumulative effect adjustment to expense if our estimates change from the prior period. We do not estimate forfeiture rates; rather, we adjust for forfeitures in the periods in which they occur. Shares underlying RSU and PSU awards are issued on the vesting dates, or later if distribution of such shares has been deferred beyond the vesting date, net of any minimum statutory tax withholdings to be paid by us on behalf of our employees. As a result, the actual number of shares issued will be fewer than the actual number of awards outstanding. When awards vest, we record a liability for withholding amounts to be paid by us as a reduction to additional paid-in capital.
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 (loss) available (attributable) to common stockholders 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.
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 and Cash Equivalents Restricted cash and cash equivalents includes cash and cash equivalents pledged as collateral for clearing and executing trades, repurchase agreements and other borrowings, and interest rate swaps and other derivative instruments. Restricted cash and cash equivalents are carried at cost, which approximates fair value.
Investment Securities	Investment Securities Agency RMBS consist of residential mortgage pass-through securities and collateralized mortgage obligations ("CMOs") guaranteed by the Federal National Mortgage Association ("Fannie Mae"), Federal Home Loan Mortgage Corporation ("Freddie Mac," and together with Fannie Mae, the "GSEs") or the Government National Mortgage Association ("Ginnie Mae"). CRT securities are risk sharing instruments issued by the GSEs, and similarly structured transactions issued by third-party market participants, that transfer a portion of the risk associated with credit losses within pools of conventional residential mortgage loans from the GSEs and/or third parties to private investors. Unlike Agency RMBS, full repayment of the original principal balance of CRT securities is not guaranteed by a GSE or U.S. Government agency; rather, "credit risk transfer" is achieved by writing down the outstanding principal balance of the CRT securities if credit losses on a related pool of loans exceed certain thresholds. By reducing the amount that they are obligated to repay to holders of CRT securities, the GSEs and/or other third parties offset credit losses on the related loans. Non-Agency RMBS and CMBS (together, "Non-Agency MBS") are backed by residential and commercial mortgage loans, respectively, packaged and securitized by a private institution, such as a commercial bank. Non-Agency MBS typically benefit from credit enhancements derived from structural elements, such as subordination, overcollateralization or insurance, but nonetheless carry a higher level of credit exposure than Agency RMBS. Accounting Standards Codification ("ASC") Topic 320, Investments—Debt and Equity Securities , 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. Alternatively, we may elect the fair value option of accounting for securities pursuant to ASC Topic 825, Financial Instruments . Prior to fiscal year 2017, we primarily designated our investment securities as available-for-sale. On January 1, 2017, we began electing the fair value option of accounting for all investment securities acquired after fiscal year 2016. Consequently, all of our securities are reported at fair value on our consolidated balance sheet. Unrealized gains and losses on securities classified as available-for-sale are reported in accumulated other comprehensive income ("OCI"). Unrealized gains and losses on securities for which we elected the fair value option or are classified as trading are reported in net income through other gain (loss) during the period in which they occur. Upon the sale of a security designated as available-for-sale, 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. In our view, the election of the fair value option simplifies the accounting for investment securities and more appropriately reflects the results of our operations for a reporting period, as the fair value changes for these assets are presented in a manner consistent with the presentation and timing of the fair value changes of our derivative instruments. We estimate the fair value of our investment securities based on prices provided by multiple third-party pricing services and non-binding dealer quotes (collectively "pricing sources"). These pricing sources use various valuation approaches, including market and income approaches, using "Level 2" inputs. The pricing sources primarily utilize a matrix pricing technique that interpolates the estimated fair value of our Agency RMBS based on observed quoted prices for forward contracts in the Agency RMBS "to-be-announced" market ("TBA securities") of the same coupon, maturity and issuer, adjusted to reflect the specific characteristics of the pool of mortgages underlying the Agency security, which may include maximum loan balance, loan vintage, loan-to-value ratio, geography and other characteristics as may be appropriate. The pricing sources may also utilize discounted cash flow model-derived pricing techniques to estimate the fair value of investment securities. Such models incorporate market-based discount rate assumptions based on observable inputs such as recent trading activity, credit data, volatility statistics, benchmark interest rate curves and other market data that are current as of the measurement date and may include certain unobservable inputs, such as assumptions of future levels of prepayment, defaults and loss severities. We review the pricing estimates obtained from the pricing sources and perform procedures to validate their reasonableness. Refer to Note 8 for further discussion of fair value measurements. We evaluate our investments designated as available-for-sale 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 exists 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. We did not recognize OTTI charges on our investment securities for fiscal years 2018, 2017 or 2016.
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 Agency RMBS and non-Agency MBS of high credit quality are amortized or accreted into interest income, respectively, over the projected lives of the securities, including contractual payments and estimated prepayments, using the effective interest method in accordance with ASC Subtopic 310-20, Receivables—Nonrefundable Fees and Other Costs . We estimate long-term prepayment speeds of our mortgage securities using a third-party service and market data. The third-party service provider estimates prepayment speeds using models that incorporate the forward yield curve, current mortgage rates, mortgage rates of the outstanding loans, age and size of the outstanding loans, loan-to-value ratios, interest rate 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 third-party estimates. We review our actual and anticipated prepayment experience on at least a quarterly basis and effective yields are recalculated when differences arise between (i) our previously estimated future prepayments and (ii) actual prepayments to date and our current 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. At the time we purchase CRT securities and non-Agency MBS that are not of high credit quality, we determine an effective yield based on our estimate of the timing and amount of future cash flows and our cost basis. Our initial cash flow estimates for these investments are based on our observations of current information and events and include assumptions related to interest rates, prepayment rates and the impact of default and severity rates on the timing and amount of credit losses. On at least a quarterly basis, we review the estimated cash flows and make appropriate adjustments based on inputs and analysis received from external sources, internal models, and our judgment regarding such inputs and other factors. Any resulting changes in effective yield are recognized prospectively based on the current amortized cost of the investment adjusted for credit impairments, if any.
Repurchase and Resale Agreements Policy [Policy Text Block]	Repurchase Agreements We finance the acquisition of securities for our investment portfolio primarily through repurchase transactions under master repurchase agreements. Pursuant to ASC Topic 860, Transfers and Servicing , we account for repurchase transactions as collateralized financing transactions, which are carried at their contractual amounts (cost), plus accrued interest. Our repurchase agreements typically have maturities of less than one year but may extend up to five years or more. Interest rates on our repurchase agreements generally correspond to one or three-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.
Derivative Instruments	Derivative Instruments We use a variety of derivative instruments to hedge a portion of our exposure to market risks, including interest rate, prepayment, extension and liquidity risks. 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 primary instruments that we use are interest rate swaps, options to enter into interest rate swaps ("swaptions"), U.S. Treasury securities and U.S. Treasury futures contracts. We also use forward contracts in the Agency RMBS "to-be-announced" market, or TBA securities, to invest in and finance Agency securities as well as to periodically reduce our exposure to Agency RMBS. 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 our accompanying consolidated balance sheets and to measure those instruments at fair value. None of our derivative instruments have been designated as hedging instruments for accounting purposes under the provisions of ASC 815, consequently changes in the fair value of our derivative instruments are reported in gain (loss) on derivative instruments and other securities, net in our consolidated statements of comprehensive income. Our derivative agreements generally contain provisions that allow for netting or setting off derivative assets and liabilities with the 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 derivative instruments creates exposure to credit risk relating to potential losses that could be recognized if the counterparties to these instruments fail to perform their obligations under the contracts. Our derivative agreements require that we post or receive collateral to mitigate such risk. We also attempt to minimize our risk of loss by limiting our counterparties to registered central clearing exchanges and major financial institutions with acceptable credit ratings, monitoring positions with individual counterparties and adjusting posted collateral as required. Interest rate swap agreements We use interest rate swaps to economically hedge the variable cash flows associated with our borrowings made under repurchase agreements. Under our interest rate swap agreements, we typically pay a fixed rate and receive a floating rate based on one or three-month LIBOR ("payer swaps") with terms up to 20 years. The majority of our interest rate swaps are centrally cleared through a registered commodities exchange. We value centrally cleared interest rate swaps using the daily settlement price, or fair value, determined by the clearing exchange based on a pricing model that references observable market inputs, including LIBOR, swap rates and the forward yield curve. Our centrally cleared swaps require that we post an "initial margin" amount determined by the clearing exchange, which is generally intended to be set at a level sufficient to protect the exchange from the interest rate swap's maximum estimated single-day price movement. We also exchange daily settlements of "variation margin" based upon changes in fair value, as measured by the exchange. Pursuant to rules governing central clearing activities, we recognize variation margin settlements as a direct reduction of the carrying value of the interest rate swap asset or liability. We value non-centrally cleared swaps using a combination of third-party valuations obtained from pricing services and the swap counterparty. The third-party valuations are model-driven using observable inputs, including LIBOR, swap rates and the forward yield curve. We also consider 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 assess 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, more rapid changes in interest rates on the performance of our investment portfolio. 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 interest rate swaption agreements are not subject to central clearing. The premium paid for interest rate swaptions is reported as an asset in our consolidated balance sheets. 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. The difference between the premium paid 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 and the premium paid. TBA securities A TBA security is a forward contract for the purchase or sale of Agency RMBS at a predetermined price, face amount, issuer, coupon and stated maturity on an agreed-upon future date. The specific Agency RMBS to be delivered into the contract are not known until shortly before the settlement date. We may choose, prior to settlement, to move the settlement of these securities out to a later date by entering into an offsetting TBA position, net settling the offsetting positions for cash, and simultaneously purchasing or selling a similar TBA contract for a later settlement date (together referred to as a "dollar roll transaction"). The Agency securities purchased or sold for a forward settlement date are typically priced at a discount to equivalent securities settling in the current month. This difference, or "price drop," is the economic equivalent of interest income on the underlying Agency securities, less an implied funding cost, over the forward settlement period (referred to as "dollar roll income"). Consequently, forward purchases of Agency securities and dollar roll transactions represent a form of off-balance sheet financing. We account for TBA contracts as derivative instruments since either the TBA contracts do not settle in the shortest period of time possible or we cannot assert that it is probable at inception and throughout the term of the TBA contract that we will physically settle the contract on the settlement date. We account for TBA dollar roll transactions as a series of derivative transactions. We estimate the fair value of TBA securities based on similar methods used to value our Agency RMBS securities. U.S. Treasury securities We use U.S. Treasury securities and U.S. Treasury futures contracts to mitigate the potential impact of changes in interest rates on the performance of our portfolio. We borrow U.S. Treasury securities under reverse repurchase agreements to cover short sales of U.S. Treasury securities. We account for these as securities borrowing transactions and recognize an obligation to return the borrowed securities at fair value on our accompanying consolidated balance sheets based on the value of the underlying U.S. Treasury security as of the reporting date. Gains and losses associated with 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.
Contingencies Disclosure [Text Block]	Loss Contingencies We evaluate the existence of any pending or threatened litigation or other potential claims against the Company in accordance with ASC Topic 450, Contingencies, which requires that we assess the likelihood and range of potential outcomes of any such matters. We are the defendant in three stockholder derivative lawsuits alleging that certain of our current and former directors and officers breached fiduciary duties and wasted corporate assets relating to past renewals of the management agreement with our former external manager and the internalization of our management on July 1, 2016. Although the outcomes of these cases cannot be predicted with certainty, we do not believe that these cases have merit or will result in a material liability, and, as of December 31, 2018 , we did not accrue a loss contingency related to these matters.
Income Tax Disclosure [Text Block]	Income Taxes As of December 31, 2018, we have distributed all of our estimated taxable income for fiscal year 2018. Accordingly, we do not expect to incur an income tax liability on our 2018 taxable income. For fiscal years 2017 and 2016, we distributed all of our taxable income within the time limits prescribed by the Internal Revenue Code. Accordingly, we did not incur an income tax liability on our taxable income for such periods. 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, 2018, 2017 and 2016. Our tax returns for tax years 2015 and forward are open to examination by the IRS. If we incur income tax related interest and penalties, our policy is to classify them as a component of provision for income taxes.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Share-based Compensation, Option and Incentive Plans Policy [Policy Text Block]	Stock-Based Compensation We measure and recognize compensation expense for all stock-based payment awards made to employees and independent directors based on their fair values. Stock-based awards issued under our equity incentive plan include time-based and performance-based restricted stock unit awards ("RSU" and "PSU" awards, respectively). An RSU and PSU awards are an agreement to issue an equivalent number of shares of our common stock, plus any equivalent shares for dividends declared on our common stock, at the time the award vests, or later if distribution of such shares has been deferred beyond the vesting date. RSU awards vest over a specified service period. PSU awards vest over a specified service period subject to achieving long-term performance criteria. We value RSU and PSU awards based on the fair value of our common stock on the date of grant. Compensation expense is recognized over each award’s respective service period. In the case of PSU awards, we estimate the probability that the performance criteria will be achieved and recognize expense only for those awards expected to vest. We reevaluate our estimates each reporting period and recognize a cumulative effect adjustment to expense if our estimates change from the prior period. We do not estimate forfeiture rates; rather, we adjust for forfeitures in the periods in which they occur. Shares underlying RSU and PSU awards are issued on the vesting dates, or later if distribution of such shares has been deferred beyond the vesting date, net of any minimum statutory tax withholdings to be paid by us on behalf of our employees. As a result, the actual number of shares issued will be fewer than the actual number of awards outstanding. When awards vest, we record a liability for withholding amounts to be paid by us as a reduction to additional paid-in capital.
Derivatives, Policy [Policy Text Block]	Derivative Instruments We use a variety of derivative instruments to hedge a portion of our exposure to market risks, including interest rate, prepayment, extension and liquidity risks. 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 primary instruments that we use are interest rate swaps, options to enter into interest rate swaps ("swaptions"), U.S. Treasury securities and U.S. Treasury futures contracts. We also use forward contracts in the Agency RMBS "to-be-announced" market, or TBA securities, to invest in and finance Agency securities as well as to periodically reduce our exposure to Agency RMBS. 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 our accompanying consolidated balance sheets and to measure those instruments at fair value. None of our derivative instruments have been designated as hedging instruments for accounting purposes under the provisions of ASC 815, consequently changes in the fair value of our derivative instruments are reported in gain (loss) on derivative instruments and other securities, net in our consolidated statements of comprehensive income. Our derivative agreements generally contain provisions that allow for netting or setting off derivative assets and liabilities with the 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 derivative instruments creates exposure to credit risk relating to potential losses that could be recognized if the counterparties to these instruments fail to perform their obligations under the contracts. Our derivative agreements require that we post or receive collateral to mitigate such risk. We also attempt to minimize our risk of loss by limiting our counterparties to registered central clearing exchanges and major financial institutions with acceptable credit ratings, monitoring positions with individual counterparties and adjusting posted collateral as required. Interest rate swap agreements We use interest rate swaps to economically hedge the variable cash flows associated with our borrowings made under repurchase agreements. Under our interest rate swap agreements, we typically pay a fixed rate and receive a floating rate based on one or three-month LIBOR ("payer swaps") with terms up to 20 years. The majority of our interest rate swaps are centrally cleared through a registered commodities exchange. We value centrally cleared interest rate swaps using the daily settlement price, or fair value, determined by the clearing exchange based on a pricing model that references observable market inputs, including LIBOR, swap rates and the forward yield curve. Our centrally cleared swaps require that we post an "initial margin" amount determined by the clearing exchange, which is generally intended to be set at a level sufficient to protect the exchange from the interest rate swap's maximum estimated single-day price movement. We also exchange daily settlements of "variation margin" based upon changes in fair value, as measured by the exchange. Pursuant to rules governing central clearing activities, we recognize variation margin settlements as a direct reduction of the carrying value of the interest rate swap asset or liability. We value non-centrally cleared swaps using a combination of third-party valuations obtained from pricing services and the swap counterparty. The third-party valuations are model-driven using observable inputs, including LIBOR, swap rates and the forward yield curve. We also consider 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 assess 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, more rapid changes in interest rates on the performance of our investment portfolio. 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 interest rate swaption agreements are not subject to central clearing. The premium paid for interest rate swaptions is reported as an asset in our consolidated balance sheets. 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. The difference between the premium paid 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 and the premium paid. TBA securities A TBA security is a forward contract for the purchase or sale of Agency RMBS at a predetermined price, face amount, issuer, coupon and stated maturity on an agreed-upon future date. The specific Agency RMBS to be delivered into the contract are not known until shortly before the settlement date. We may choose, prior to settlement, to move the settlement of these securities out to a later date by entering into an offsetting TBA position, net settling the offsetting positions for cash, and simultaneously purchasing or selling a similar TBA contract for a later settlement date (together referred to as a "dollar roll transaction"). The Agency securities purchased or sold for a forward settlement date are typically priced at a discount to equivalent securities settling in the current month. This difference, or "price drop," is the economic equivalent of interest income on the underlying Agency securities, less an implied funding cost, over the forward settlement period (referred to as "dollar roll income"). Consequently, forward purchases of Agency securities and dollar roll transactions represent a form of off-balance sheet financing. We account for TBA contracts as derivative instruments since either the TBA contracts do not settle in the shortest period of time possible or we cannot assert that it is probable at inception and throughout the term of the TBA contract that we will physically settle the contract on the settlement date. We account for TBA dollar roll transactions as a series of derivative transactions. We estimate the fair value of TBA securities based on similar methods used to value our Agency RMBS securities. U.S. Treasury securities We use U.S. Treasury securities and U.S. Treasury futures contracts to mitigate the potential impact of changes in interest rates on the performance of our portfolio. We borrow U.S. Treasury securities under reverse repurchase agreements to cover short sales of U.S. Treasury securities. We account for these as securities borrowing transactions and recognize an obligation to return the borrowed securities at fair value on our accompanying consolidated balance sheets based on the value of the underlying U.S. Treasury security as of the reporting date. Gains and losses associated with 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.
Investment, Policy [Policy Text Block]	Investment Securities Agency RMBS consist of residential mortgage pass-through securities and collateralized mortgage obligations ("CMOs") guaranteed by the Federal National Mortgage Association ("Fannie Mae"), Federal Home Loan Mortgage Corporation ("Freddie Mac," and together with Fannie Mae, the "GSEs") or the Government National Mortgage Association ("Ginnie Mae"). CRT securities are risk sharing instruments issued by the GSEs, and similarly structured transactions issued by third-party market participants, that transfer a portion of the risk associated with credit losses within pools of conventional residential mortgage loans from the GSEs and/or third parties to private investors. Unlike Agency RMBS, full repayment of the original principal balance of CRT securities is not guaranteed by a GSE or U.S. Government agency; rather, "credit risk transfer" is achieved by writing down the outstanding principal balance of the CRT securities if credit losses on a related pool of loans exceed certain thresholds. By reducing the amount that they are obligated to repay to holders of CRT securities, the GSEs and/or other third parties offset credit losses on the related loans. Non-Agency RMBS and CMBS (together, "Non-Agency MBS") are backed by residential and commercial mortgage loans, respectively, packaged and securitized by a private institution, such as a commercial bank. Non-Agency MBS typically benefit from credit enhancements derived from structural elements, such as subordination, overcollateralization or insurance, but nonetheless carry a higher level of credit exposure than Agency RMBS. Accounting Standards Codification ("ASC") Topic 320, Investments—Debt and Equity Securities , 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. Alternatively, we may elect the fair value option of accounting for securities pursuant to ASC Topic 825, Financial Instruments . Prior to fiscal year 2017, we primarily designated our investment securities as available-for-sale. On January 1, 2017, we began electing the fair value option of accounting for all investment securities acquired after fiscal year 2016. Consequently, all of our securities are reported at fair value on our consolidated balance sheet. Unrealized gains and losses on securities classified as available-for-sale are reported in accumulated other comprehensive income ("OCI"). Unrealized gains and losses on securities for which we elected the fair value option or are classified as trading are reported in net income through other gain (loss) during the period in which they occur. Upon the sale of a security designated as available-for-sale, 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. In our view, the election of the fair value option simplifies the accounting for investment securities and more appropriately reflects the results of our operations for a reporting period, as the fair value changes for these assets are presented in a manner consistent with the presentation and timing of the fair value changes of our derivative instruments. We estimate the fair value of our investment securities based on prices provided by multiple third-party pricing services and non-binding dealer quotes (collectively "pricing sources"). These pricing sources use various valuation approaches, including market and income approaches, using "Level 2" inputs. The pricing sources primarily utilize a matrix pricing technique that interpolates the estimated fair value of our Agency RMBS based on observed quoted prices for forward contracts in the Agency RMBS "to-be-announced" market ("TBA securities") of the same coupon, maturity and issuer, adjusted to reflect the specific characteristics of the pool of mortgages underlying the Agency security, which may include maximum loan balance, loan vintage, loan-to-value ratio, geography and other characteristics as may be appropriate. The pricing sources may also utilize discounted cash flow model-derived pricing techniques to estimate the fair value of investment securities. Such models incorporate market-based discount rate assumptions based on observable inputs such as recent trading activity, credit data, volatility statistics, benchmark interest rate curves and other market data that are current as of the measurement date and may include certain unobservable inputs, such as assumptions of future levels of prepayment, defaults and loss severities. We review the pricing estimates obtained from the pricing sources and perform procedures to validate their reasonableness. Refer to Note 8 for further discussion of fair value measurements. We evaluate our investments designated as available-for-sale 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 exists 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. We did not recognize OTTI charges on our investment securities for fiscal years 2018, 2017 or 2016.
Interest Income [Policy Text Block]	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 Agency RMBS and non-Agency MBS of high credit quality are amortized or accreted into interest income, respectively, over the projected lives of the securities, including contractual payments and estimated prepayments, using the effective interest method in accordance with ASC Subtopic 310-20, Receivables—Nonrefundable Fees and Other Costs . We estimate long-term prepayment speeds of our mortgage securities using a third-party service and market data. The third-party service provider estimates prepayment speeds using models that incorporate the forward yield curve, current mortgage rates, mortgage rates of the outstanding loans, age and size of the outstanding loans, loan-to-value ratios, interest rate 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 third-party estimates. We review our actual and anticipated prepayment experience on at least a quarterly basis and effective yields are recalculated when differences arise between (i) our previously estimated future prepayments and (ii) actual prepayments to date and our current 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. At the time we purchase CRT securities and non-Agency MBS that are not of high credit quality, we determine an effective yield based on our estimate of the timing and amount of future cash flows and our cost basis. Our initial cash flow estimates for these investments are based on our observations of current information and events and include assumptions related to interest rates, prepayment rates and the impact of default and severity rates on the timing and amount of credit losses. On at least a quarterly basis, we review the estimated cash flows and make appropriate adjustments based on inputs and analysis received from external sources, internal models, and our judgment regarding such inputs and other factors. Any resulting changes in effective yield are recognized prospectively based on the current amortized cost of the investment adjusted for credit impairments, if any.

Investment Securities (Tables)

Investment Securities (Tables)	12 Months Ended
	Dec. 31, 2018
Investments, Debt and Equity Securities [Abstract]
Securities by Credit Rating [Table Text Block]	As of December 31, 2018 and 2017 , our investments in CRT and non-Agency securities had the following credit ratings: December 31, 2018 December 31, 2017 CRT and Non-Agency Security Credit Ratings 1 CRT RMBS CMBS CRT RMBS CMBS AAA $ — $ 160 $ 52 $ — $ 7 $ — AA — 17 152 — — — A 17 33 15 1 — — BBB 25 43 53 34 — 29 BB 492 8 10 370 — — B 453 2 — 455 — — Not Rated 25 3 — 16 — — Total $ 1,012 $ 266 $ 282 $ 876 $ 7 $ 29 ________________________________ 1. Represents the lowest of Standard and Poor's ("S&P"), Moody's, Fitch, DBRS, Kroll Bond Rating Agency ("KBRA") and Morningstar credit ratings, stated in terms of the S&P equivalent rating as of each date.
Available-for-sale Securities [Table Text Block]	December 31, 2018 Agency RMBS Non-Agency Investment Securities Fannie Mae Freddie Mac Ginnie Mae RMBS CMBS CRT Total Available-for-sale securities: Par value $ 17,591 $ 5,673 $ 25 $ 6 $ — $ — $ 23,295 Unamortized discount (10 ) (2 ) — — — — (12 ) Unamortized premium 912 343 — — — — 1,255 Amortized cost 18,493 6,014 25 6 — — 24,538 Gross unrealized gains 4 2 1 — — — 7 Gross unrealized losses (686 ) (264 ) — — — — (950 ) Total available-for-sale securities, at fair value 17,811 5,752 26 6 — — 23,595 Securities remeasured at fair value through earnings: Par value 39,453 18,428 — 268 281 968 59,398 Unamortized discount (78 ) (9 ) — (10 ) (6 ) — (103 ) Unamortized premium 1,055 638 — — 5 38 1,736 Amortized cost 40,430 19,057 — 258 280 1,006 61,031 Gross unrealized gains 223 57 — 2 3 18 303 Gross unrealized losses (386 ) (243 ) — — (1 ) (12 ) (642 ) Total securities remeasured at fair value through earnings 40,267 18,871 — 260 282 1,012 60,692 Total securities, at fair value $ 58,078 $ 24,623 $ 26 $ 266 $ 282 $ 1,012 $ 84,287 Weighted average coupon as of December 31, 2018 3.82 % 3.87 % 3.37 % 3.83 % 4.58 % 5.86 % 3.86 % Weighted average yield as of December 31, 2018 1 3.28 % 3.28 % 2.04 % 4.22 % 4.68 % 5.16 % 3.31 % ________________________________ 1. Incorporates a weighted average future constant prepayment rate assumption of 7.9% based on forward rates as of December 31, 2018 . December 31, 2017 Agency RMBS Non-Agency Investment Securities Fannie Mae Freddie Mac Ginnie Mae RMBS CMBS CRT Total Available-for-sale securities: Par value $ 24,200 $ 8,219 $ 34 $ 7 $ — $ — $ 32,460 Unamortized discount (25 ) (3 ) — — — — (28 ) Unamortized premium 1,119 447 — — — — 1,566 Amortized cost 25,294 8,663 34 7 — — 33,998 Gross unrealized gains 98 22 1 — — — 121 Gross unrealized losses (325 ) (141 ) — — — — (466 ) Total available-for-sale securities, at fair value 25,067 8,544 35 7 — — 33,653 Securities remeasured at fair value through earnings: Par value 13,558 7,956 — — 29 801 22,344 Unamortized discount (34 ) — — — (1 ) — (35 ) Unamortized premium 711 415 — — — 33 1,159 Amortized cost 14,235 8,371 — — 28 834 23,468 Gross unrealized gains 26 2 — — 1 42 71 Gross unrealized losses (70 ) (42 ) — — — — (112 ) Total securities remeasured at fair value through earnings 14,191 8,331 — — 29 876 23,427 Total securities, at fair value $ 39,258 $ 16,875 $ 35 $ 7 $ 29 $ 876 $ 57,080 Weighted average coupon as of December 31, 2017 3.67 % 3.73 % 2.84 % 2.50 % 6.55 % 5.26 % 3.71 % Weighted average yield as of December 31, 2017 1 2.84 % 2.87 % 2.02 % 3.08 % 7.30 % 5.19 % 2.89 % ________________________________ 1. Incorporates a weighted average future constant prepayment rate assumption of 8.4% based on forward rates as of December 31, 2017 .
Components of Investment Securities	The following tables summarize our investment securities as of December 31, 2018 and 2017 , excluding TBA securities, (dollars in millions). Details of our TBA securities as of each of the respective dates are included in Note 5 . December 31, 2018 December 31, 2017 Investment Securities Amortized Cost Fair Value Amortized Fair Value Agency RMBS: Fixed rate $ 83,047 $ 81,753 $ 55,477 $ 55,026 Adjustable rate 212 213 278 283 CMO 588 583 629 631 Interest-only and principal-only strips 172 178 213 228 Total Agency RMBS 84,019 82,727 56,597 56,168 Non-Agency RMBS 264 266 7 7 CMBS 280 282 28 29 CRT securities 1,006 1,012 834 876 Total investment securities $ 85,569 $ 84,287 $ 57,466 $ 57,080 December 31, 2018 Agency RMBS Non-Agency Investment Securities Fannie Mae Freddie Mac Ginnie Mae RMBS CMBS CRT Total Available-for-sale securities: Par value $ 17,591 $ 5,673 $ 25 $ 6 $ — $ — $ 23,295 Unamortized discount (10 ) (2 ) — — — — (12 ) Unamortized premium 912 343 — — — — 1,255 Amortized cost 18,493 6,014 25 6 — — 24,538 Gross unrealized gains 4 2 1 — — — 7 Gross unrealized losses (686 ) (264 ) — — — — (950 ) Total available-for-sale securities, at fair value 17,811 5,752 26 6 — — 23,595 Securities remeasured at fair value through earnings: Par value 39,453 18,428 — 268 281 968 59,398 Unamortized discount (78 ) (9 ) — (10 ) (6 ) — (103 ) Unamortized premium 1,055 638 — — 5 38 1,736 Amortized cost 40,430 19,057 — 258 280 1,006 61,031 Gross unrealized gains 223 57 — 2 3 18 303 Gross unrealized losses (386 ) (243 ) — — (1 ) (12 ) (642 ) Total securities remeasured at fair value through earnings 40,267 18,871 — 260 282 1,012 60,692 Total securities, at fair value $ 58,078 $ 24,623 $ 26 $ 266 $ 282 $ 1,012 $ 84,287 Weighted average coupon as of December 31, 2018 3.82 % 3.87 % 3.37 % 3.83 % 4.58 % 5.86 % 3.86 % Weighted average yield as of December 31, 2018 1 3.28 % 3.28 % 2.04 % 4.22 % 4.68 % 5.16 % 3.31 %
Summary Of Agency Securities Estimated Weighted Average Life Classifications	The following table summarizes our investments as of December 31, 2018 and 2017 according to their estimated weighted average life classification (dollars in millions): December 31, 2018 December 31, 2017 Estimated Weighted Average Life of Investment Securities Fair Value Amortized Cost Weighted Average Coupon Weighted Average Yield Fair Value Amortized Cost Weighted Average Coupon Weighted Average Yield ≥ 1 year and ≤ 3 years $ 1,690 $ 1,716 3.99% 2.64% $ 2,712 $ 2,693 3.90% 2.67% > 3 years and ≤ 5 years 5,518 5,586 3.35% 2.73% 7,499 7,518 3.31% 2.39% > 5 years and ≤10 years 72,503 73,588 3.92% 3.37% 45,977 46,398 3.75% 2.95% > 10 years 4,576 4,679 3.57% 3.30% 892 857 4.87% 4.74% Total $ 84,287 $ 85,569 3.86% 3.31% $ 57,080 $ 57,466 3.71% 2.89%
Summary of Continuous Unrealized Loss Position of Available for Sale Securities	The following table presents the gross unrealized loss and fair values of securities classified as available-for-sale by length of time that such securities have been in a continuous unrealized loss position as of December 31, 2018 and 2017 (in millions): Unrealized Loss Position For Less than 12 Months 12 Months or More Total Securities Classified as Available-for-Sale Fair Value Unrealized Loss Fair Value Unrealized Loss Fair Value Unrealized Loss December 31, 2018 $ 4,783 $ (72 ) $ 18,231 $ (878 ) $ 23,014 $ (950 ) December 31, 2017 $ 3,582 $ (15 ) $ 20,577 $ (451 ) $ 24,159 $ (466 )
Summary of Net Gain from Sale of Agency Securities	The following table is a summary of our net gain (loss) from the sale of investment securities for fiscal years 2018 , 2017 and 2016 by investment classification of accounting (in millions): Fiscal Year 2018 Fiscal Year 2017 Fiscal Year 2016 Investment Securities Available-for-Sale Securities 2 Fair Value Option Securities Total Available-for-Sale Securities 2 Fair Value Option Securities Total Available-for-Sale 2 Fair Value Option Securities Total Investment securities sold, at cost $ (4,306 ) $ (5,344 ) $ (9,650 ) $ (6,324 ) $ (12,913 ) $ (19,237 ) $ (17,907 ) $ — $ (17,907 ) Proceeds from investment securities sold 1 4,227 5,286 9,513 6,241 12,933 19,174 18,016 — 18,016 Net gain (loss) on sale of investment securities $ (79 ) $ (58 ) $ (137 ) $ (83 ) $ 20 $ (63 ) $ 109 $ — $ 109 Gross gain on sale of investment securities $ 6 $ 16 $ 22 $ 16 $ 48 $ 64 $ 123 $ — $ 123 Gross loss on sale of investment securities (85 ) (74 ) (159 ) (99 ) (28 ) (127 ) (14 ) — (14 ) Net gain (loss) on sale of investment securities $ (79 ) $ (58 ) $ (137 ) $ (83 ) $ 20 $ (63 ) $ 109 $ — $ 109 ________________________________ 1. Proceeds include cash received during the period, plus receivable for investment securities sold during the period as of period end. 2. See Note 9 for a summary of changes in accumulated OCI.

Repurchase Agreements and Rev_2

Repurchase Agreements and Reverse Repurchase Agreements (Tables)	12 Months Ended
	Dec. 31, 2018
Disclosure of Repurchase Agreements [Abstract]
Schedule of Borrowings under Repurchase Agreements and Weighted Average Interest Rates	The following table summarizes our borrowings under repurchase agreements by their remaining maturities as of December 31, 2018 and 2017 (dollars in millions): December 31, 2018 December 31, 2017 Remaining Maturity Repurchase Agreements Weighted Average Interest Rate Weighted Average Days to Maturity Repurchase Agreements Weighted Average Interest Rate Weighted Average Days to Maturity ≤ 1 month $ 48,533 2.88 % 9 $ 19,771 1.59 % 11 > 1 to ≤ 3 months 20,991 2.57 % 56 16,150 1.50 % 50 > 3 to ≤ 6 months 2,218 2.65 % 167 7,287 1.50 % 130 > 6 to ≤ 9 months 200 3.19 % 208 2,361 1.66 % 225 > 9 to ≤ 12 months 950 2.80 % 279 202 1.64 % 297 > 12 to ≤ 24 months 2,200 2.91 % 438 1,700 1.84 % 468 > 24 to ≤ 36 months 625 3.11 % 776 2,200 1.80 % 803 > 36 to ≤ 48 months — — % — 625 1.90 % 1,141 Total $ 75,717 2.79 % 49 $ 50,296 1.57 % 116

Derivative and Other Hedging _2

Derivative and Other Hedging Instruments (Tables)	12 Months Ended
	Dec. 31, 2018
Derivative [Line Items]
Schedule of Outstanding Derivatives Not Designated as Hedging Instruments	The table below summarizes fair value information about our derivative and other hedging instrument assets/(liabilities) as of December 31, 2018 and 2017 (in millions): December 31, Derivative and Other Hedging Instruments Balance Sheet Location 2018 2017 Interest rate swaps Derivative assets, at fair value $ 126 $ 81 Swaptions Derivative assets, at fair value 37 75 TBA securities Derivative assets, at fair value 110 30 U.S. Treasury futures - short Derivative assets, at fair value — 19 Total derivative assets, at fair value $ 273 $ 205 Interest rate swaps Derivative liabilities, at fair value $ — $ (1 ) TBA securities Derivative liabilities, at fair value (40 ) (27 ) U.S. Treasury futures - short Derivative liabilities, at fair value (44 ) — Total derivative liabilities, at fair value $ (84 ) $ (28 ) U.S. Treasury securities - long U.S. Treasury securities, at fair value $ 46 $ — U.S. Treasury securities - short Obligation to return securities borrowed under reverse repurchase agreements, at fair value (21,431 ) (10,467 ) Total U.S. Treasury securities, net at fair value $ (21,385 ) $ (10,467 )
Schedule of Interest Rate Swaption Agreements Outstanding	Swaptions Option Underlying Payer Swap Current Option Expiration Date Cost Basis Fair Value Average Months to Current Option Expiration Date 1 Notional Amount Average Fixed Pay Rate Average Receive Rate (LIBOR) Average Term (Years) December 31, 2018 ≤ 1 year $ 80 $ 23 4 $ 3,000 2.96% 3M 7.0 > 1 year ≤ 2 years 18 14 18 500 2.78% 3M 10.0 Total $ 98 $ 37 6 $ 3,500 2.93% 3M 7.4 December 31, 2017 ≤ 1 year $ 118 $ 46 7 $ 5,100 2.71% 3M 8.8 > 1 year ≤ 2 years 23 16 18 1,050 2.71% 3M 8.7 > 2 year ≤ 3 years 18 13 30 500 2.78% 3M 10.0 Total $ 159 $ 75 10 $ 6,650 2.72% 3M 8.9 ________________________________ 1. As of December 31, 2018 and 2017 , ≤ 1 year notional amount includes $700 million of Bermudan swaptions where the options may be exercised on predetermined dates up to their final exercise date, which is six months prior to the underlying swaps' maturity date. U.S. Treasury Securities December 31, 2018 December 31, 2017 Maturity Face Amount (Short) Cost Basis 1 Fair Value Face Amount (Short) Cost Basis 1 Fair Value 5 years $ (703 ) $ (706 ) $ (713 ) $ (288 ) $ (286 ) $ (283 ) 7 years (14,357 ) (14,325 ) (14,410 ) (6,131 ) (6,106 ) (6,029 ) 10 years (6,240 ) (6,224 ) (6,262 ) (4,280 ) (4,230 ) (4,155 ) Total U.S. Treasury securities $ (21,300 ) $ (21,255 ) $ (21,385 ) $ (10,699 ) $ (10,622 ) $ (10,467 )
US government securities	U.S. Treasury Securities December 31, 2018 December 31, 2017 Maturity Face Amount (Short) Cost Basis 1 Fair Value Face Amount (Short) Cost Basis 1 Fair Value 5 years $ (703 ) $ (706 ) $ (713 ) $ (288 ) $ (286 ) $ (283 ) 7 years (14,357 ) (14,325 ) (14,410 ) (6,131 ) (6,106 ) (6,029 ) 10 years (6,240 ) (6,224 ) (6,262 ) (4,280 ) (4,230 ) (4,155 ) Total U.S. Treasury securities $ (21,300 ) $ (21,255 ) $ (21,385 ) $ (10,699 ) $ (10,622 ) $ (10,467 )
US Government Futures Securities [Table Text Block]	U.S. Treasury Futures December 31, 2018 December 31, 2017 Maturity Notional Amount - Long (Short) Cost Basis Fair Value Net Carrying Value 1 Notional Amount - Long (Short) Cost Basis Fair Value Net Carrying Value 1 5 years $ — $ — $ — $ — $ (730 ) $ (852 ) $ (848 ) $ 4 10 years (1,650 ) (1,969 ) (2,013 ) (44 ) (2,180 ) (2,718 ) (2,703 ) 15 Total U.S. Treasury futures $ (1,650 ) $ (1,969 ) $ (2,013 ) $ (44 ) $ (2,910 ) $ (3,570 ) $ (3,551 ) $ 19 ________________________________ 1. Net carrying value represents the difference between the fair market value and the cost basis (or the forward price to be paid/(received) for the underlying U.S. Treasury security) of the U.S. Treasury futures contract as of period-end and is reported in derivative assets/(liabilities), at fair value in our consolidated balance sheets.
Summary of Long and Short Position of Derivative Instruments	December 31, 2018 December 31, 2017 TBA Securities by Coupon Notional Amount - Long (Short) Cost Basis Fair Value Net Carrying Value 1 Notional Amount - Long (Short) Cost Basis Fair Value Net Carrying Value 1 15-Year TBA securities: 2.5% $ — $ — $ — $ — $ 1,373 $ 1,372 $ 1,370 $ (2 ) 3.0% 567 557 566 9 3,161 3,225 3,217 (8 ) 3.5% 1,706 1,708 1,726 18 414 428 428 — 4.0% 1,350 1,370 1,381 11 — — — — Total 15-Year TBA securities 3,623 3,635 3,673 38 4,948 5,025 5,015 (10 ) 30-Year TBA securities: 3.0% 1,028 981 1,003 22 4,317 4,303 4,312 9 3.5% (2,979 ) (2,943 ) (2,977 ) (34 ) 3,932 4,027 4,034 7 4.0% 3,030 3,073 3,089 16 2,338 2,449 2,446 (3 ) ≥ 4.5% 2,450 2,506 2,534 28 (61 ) (65 ) (65 ) — Total 30-Year TBA securities, net 3,529 3,617 3,649 32 10,526 10,714 10,727 13 Total TBA securities, net $ 7,152 $ 7,252 $ 7,322 $ 70 $ 15,474 $ 15,739 $ 15,742 $ 3 ________________________________ 1. Net carrying value represents the difference between the fair market value and the cost basis (or the forward price to be paid/(received) for the underlying Agency security) of the TBA contract as of period-end and is reported in derivative assets/(liabilities), at fair value in our consolidated balance sheets.
Schedule Of Outstanding Not Designated As Hedging Instruments	The following table summarizes changes in our derivative and other hedge portfolio and their effect on our consolidated statements of comprehensive income for fiscal years 2018 , 2017 and 2016 (in millions): Derivative and Other Hedging Instruments Beginning Notional Amount Additions Settlement, Termination, Expiration or Exercise Ending Notional Amount Gain/(Loss) on Derivative Instruments and Other Securities, Net 1 Fiscal Year 2018: TBA securities, net $ 15,474 194,534 (202,856 ) $ 7,152 $ (299 ) Interest rate swaps $ 43,700 14,350 (6,425 ) $ 51,625 140 Payer swaptions $ 6,650 1,250 (4,400 ) $ 3,500 90 U.S. Treasury securities - short position $ (10,699 ) (19,278 ) 8,632 $ (21,345 ) (161 ) U.S. Treasury securities - long position $ — 1,949 (1,904 ) $ 45 1 U.S. Treasury futures contracts - short position $ (2,910 ) (7,859 ) 9,119 $ (1,650 ) 48 $ (181 ) Fiscal Year 2017: TBA securities, net $ 10,916 237,601 (233,043 ) $ 15,474 $ 330 Interest rate swaps $ 37,175 14,825 (8,300 ) $ 43,700 67 Payer swaptions $ 1,200 6,450 (1,000 ) $ 6,650 (66 ) U.S. Treasury securities - short position $ (8,061 ) (14,030 ) 11,392 $ (10,699 ) (141 ) U.S. Treasury securities - long position $ 189 404 (593 ) $ — 1 U.S. Treasury futures contracts - short position $ (1,810 ) (11,340 ) 10,240 $ (2,910 ) — $ 191 Fiscal Year 2016: TBA securities, net $ 7,295 116,439 (112,818 ) $ 10,916 $ (59 ) Interest rate swaps $ 40,525 15,650 (19,000 ) $ 37,175 (397 ) Payer swaptions $ 2,150 500 (1,450 ) $ 1,200 (3 ) U.S. Treasury securities - short position $ (1,714 ) (9,884 ) 3,537 $ (8,061 ) 7 U.S. Treasury securities - long position $ 25 961 (797 ) $ 189 134 U.S. Treasury futures contracts - short position $ (1,860 ) (7,840 ) 7,890 $ (1,810 ) (5 ) $ (323 ) ________________________________ 1. Amounts exclude other miscellaneous gains and losses recognized in gain (loss) on derivative instruments and other securities, net in our consolidated statements of comprehensive income.
Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Schedule Of Interest Rate Swap Agreement By Remaining Maturity	The following tables summarize certain characteristics of our derivative and other hedging instruments outstanding as of December 31, 2018 and 2017 (dollars in millions): December 31, 2018 December 31, 2017 Interest Rate Swaps Notional 1 Average Rate 2 Average Average Notional 1 Average Rate 2 Average Average ≤ 3 years $ 19,900 1.63% 2.62% 1.3 $ 21,025 1.40% 1.46% 1.5 > 3 to ≤ 5 years 8,425 2.06% 2.61% 4.0 6,825 1.82% 1.43% 4.1 > 5 to ≤ 7 years 7,875 2.66% 2.66% 6.1 5,775 2.02% 1.44% 5.9 > 7 to ≤ 10 years 10,550 2.36% 2.64% 8.8 6,650 2.10% 1.42% 9.1 > 10 years 4,875 2.77% 2.63% 11.6 3,425 2.49% 1.45% 12.9 Total $ 51,625 2.11% 2.63% 5.0 $ 43,700 1.74% 1.44% 4.5

Pledged Assets (Tables)

Pledged Assets (Tables)	12 Months Ended
	Dec. 31, 2018
Pledged Assets [Abstract]
Schedule of Securities and Cash Pledged as Collateral from Counterparties [Table Text Block]	As of December 31, 2018 and 2017 , we had assets pledged to us from counterparties as collateral under our reverse repurchase and derivative agreements summarized in the tables below (in millions). December 31, 2018 December 31, 2017 Assets Pledged to AGNC 1 Reverse Repurchase Agreements Derivative Agreements Repurchase Agreements Total Reverse Repurchase Agreements Derivative Agreements Repurchase Agreements Total U.S. Treasury securities - fair value $ 21,876 $ 35 $ 37 $ 21,948 $ 10,853 $ — $ — $ 10,853 Cash — 129 — 129 — 82 — 82 Total $ 21,876 $ 164 $ 37 $ 22,077 $ 10,853 $ 82 $ — $ 10,935
Schedule of Financial Instruments Owned and Pledged as Collateral	The following tables summarize our assets pledged as collateral under our funding, derivative and prime broker agreements by type, including securities pledged related to securities sold but not yet settled, as of December 31, 2018 and 2017 (in millions): December 31, 2018 Assets Pledged to Counterparties 1 Repurchase Agreements 2 Debt of Consolidated VIEs Derivative Agreements Prime Broker Agreements 3 Total Agency RMBS - fair value $ 78,997 $ 436 $ 174 $ 133 $ 79,740 CRT - fair value 141 — — — 141 Non-Agency - fair value 45 — — — 45 U.S. Treasury securities - fair value 437 — — — 437 Accrued interest on pledged securities 246 1 1 — 248 Restricted cash and cash equivalents 77 — 522 — 599 Total $ 79,943 $ 437 $ 697 $ 133 $ 81,210 December 31, 2017 Assets Pledged to Counterparties 1 Repurchase Agreements 2 Debt of Consolidated VIEs Derivative Agreements Prime Broker Agreements 3 Total Agency RMBS - fair value $ 52,497 $ 662 $ 221 $ 519 $ 53,899 U.S. Treasury securities - fair value 113 — 72 — 185 Accrued interest on pledged securities 153 2 1 2 158 Restricted cash and cash equivalents 35 — 281 1 317 Total $ 52,798 $ 664 $ 575 $ 522 $ 54,559 ________________________________ 1. Includes repledged assets received as collateral from counterparties. 2. Includes $163 million and $182 million of retained interests in our consolidated VIEs pledged as collateral under repurchase agreements as of December 31, 2018 and 2017 , respectively. 3. Includes margin for TBAs cleared through prime brokers and other clearing deposits.
Schedules Of Securities Pledged As Collateral Under Repurchase Agreement	The following table summarizes our securities pledged as collateral under our repurchase agreements by the remaining maturity of our borrowings, including securities pledged related to sold but not yet settled securities, as of December 31, 2018 and 2017 (in millions). For the corresponding borrowings associated with the following amounts and the interest rates thereon, refer to Note 4 . December 31, 2018 December 31, 2017 Securities Pledged by Remaining Maturity of Repurchase Agreements 1,2 Fair Value of Pledged Securities Amortized Cost of Pledged Securities Accrued Interest on Pledged Securities Fair Value of Pledged Securities Amortized Cost of Pledged Securities Accrued Interest on Pledged Securities ≤ 30 days $ 49,944 $ 50,654 $ 156 $ 20,162 $ 20,313 $ 59 > 30 and ≤ 60 days 14,586 14,810 46 12,950 13,061 38 > 60 and ≤ 90 days 7,770 7,843 24 4,000 4,013 11 > 90 days 6,882 7,079 21 15,385 15,512 45 Total $ 79,182 $ 80,386 $ 247 $ 52,497 $ 52,899 $ 153 ________________________________ 1. Includes $163 million and $182 million of retained interests in our consolidated VIEs pledged as collateral under repurchase agreements as of December 31, 2018 and 2017 , respectively. 2. December 31, 2018 amounts exclude $437 million
Offsetting Assets and Liabilities	The following tables present information about our assets and liabilities that are subject to master netting arrangements and can potentially be offset on our consolidated balance sheets as of December 31, 2018 and 2017 (in millions): Offsetting of Financial 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 in the Consolidated Balance Sheets Net Amount Financial Instruments Collateral Received 2 December 31, 2018 Interest rate swap and swaption agreements, at fair value 1 $ 163 $ — $ 163 $ — $ (158 ) $ 5 TBA securities, at fair value 110 — 110 (40 ) — 70 Receivable under reverse repurchase agreements 21,813 — 21,813 (17,236 ) (4,575 ) 2 Total $ 22,086 $ — $ 22,086 $ (17,276 ) $ (4,733 ) $ 77 December 31, 2017 Interest rate swap and swaption agreements, at fair value 1 $ 156 $ — $ 156 $ (1 ) $ (82 ) $ 73 TBA securities, at fair value 30 — 30 (22 ) — 8 Receivable under reverse repurchase agreements 10,961 — 10,961 (9,682 ) (1,279 ) — Total $ 11,147 $ — $ 11,147 $ (9,705 ) $ (1,361 ) $ 81
Offsetting Liabilities	Offsetting of Financial 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 in the Consolidated Balance Sheets Net Amount Financial Instruments Collateral Pledged 2 December 31, 2018 Interest rate swap agreements, at fair value 1 $ — $ — $ — $ — $ — $ — TBA securities, at fair value 40 — 40 (40 ) — — Repurchase agreements 75,717 — 75,717 (17,236 ) (58,481 ) — Total $ 75,757 $ — $ 75,757 $ (17,276 ) $ (58,481 ) $ — December 31, 2017 Interest rate swap agreements, at fair value 1 $ 1 $ — $ 1 $ (1 ) $ — $ — TBA securities, at fair value 27 — 27 (22 ) (5 ) — Repurchase agreements and FHLB advances 50,296 — 50,296 (9,682 ) (40,614 ) — Total $ 50,324 $ — $ 50,324 $ (9,705 ) $ (40,619 ) $ — ________________________________ 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 pledged / received as collateral, at fair value. Amounts include repledged collateral. Amounts presented are limited to collateral pledged sufficient to reduce the net amount to zero for individual counterparties, as applicable.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2018
Fair Value Disclosures [Abstract]
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, 2018 and 2017 based on their categorization within the valuation hierarchy (in millions). There were no transfers between valuation hierarchy levels during the periods presented. December 31, 2018 December 31, 2017 Level 1 Level 2 Level 3 Level 1 Level 2 Level 3 Assets: Agency securities $ — $ 82,291 $ — $ — $ 55,506 $ — Agency securities transferred to consolidated VIEs — 436 — — 662 — Credit risk transfer securities — 1,012 — — 876 — Non-Agency securities — 548 — — 36 — U.S. Treasury securities 46 — — — — — REIT equity securities — — — 29 — — Interest rate swaps — 126 — — 81 — Swaptions — 37 — — 75 — TBA securities — 110 — — 30 — U.S. Treasury futures — — — 19 — — Total $ 46 $ 84,560 $ — $ 48 $ 57,266 $ — Liabilities: Debt of consolidated VIEs $ — $ 275 $ — $ — $ 357 $ — Obligation to return U.S. Treasury securities borrowed under reverse repurchase agreements 21,431 — — 10,467 — — Interest rate swaps — — — — 1 — TBA securities — 40 — — 27 — U.S. Treasury futures (44 ) — — — — — Total $ 21,387 $ 315 $ — $ 10,467 $ 385 $ —

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2018
Equity [Abstract]
Schedule of Stock by Class [Table Text Block]	Follow-On Public Offering Price Received Per Share, Net Shares Net Proceeds Fiscal Year 2018: May 2018 $18.35 34.5 $ 633 August 2018 $18.68 43.7 817 November 2018 $17.09 46.0 786 Total fiscal year 2018 124.2 $ 2,236 Fiscal Year 2017: May 2017 $20.51 24.5 $ 503 September 2017 $20.47 28.2 577 Total fiscal year 2017 52.7 $ 1,080 ATM Offerings Average Price Received Per Share, Net Shares Net Proceeds Fiscal Year 2018 $18.03 20.8 $ 375 Fiscal Year 2017 $20.96 7.6 $ 159
Dividends Declared [Table Text Block]	The following table summarizes cash dividends declared for fiscal years 2018, 2017 and 2016 (in millions, except per share amounts): Dividends Declared Dividends Declared Per Share 8.000 % Series A Cumulative Redeemable Preferred Stock Fiscal year 2017 $ 9 $ 1.333000 Fiscal year 2016 $ 14 $ 2.000000 7.750% Series B Cumulative Redeemable Preferred Stock (Per Depositary Share) Fiscal year 2018 $ 14 $ 1.937500 Fiscal year 2017 $ 14 $ 1.937500 Fiscal year 2016 $ 14 $ 1.937500 7.00% Series C Fixed-to-Floating Rate Cumulative Redeemable Preferred Stock (Per Depositary Share) Fiscal year 2018 $ 23 $ 1.750000 Fiscal year 2017 $ 9 $ 0.695140 Common Stock Fiscal year 2018 $ 964 $ 2.160000 Fiscal year 2017 $ 777 $ 2.160000 Fiscal year 2016 $ 763 $ 2.300000
Schedule of Accumulated Other Comprehensive Income (Loss)	The following table summarizes changes to accumulated OCI for fiscal years 2018 , 2017 and 2016 (in millions): Fiscal Year Accumulated Other Comprehensive Income (Loss) 2018 2017 2016 Beginning Balance $ (345 ) $ (397 ) $ (66 ) OCI before reclassifications (677 ) (31 ) (261 ) (Gain) loss amounts for available-for-sale securities reclassified from accumulated OCI to realized gain (loss) on sale of investment securities 79 83 (109 ) Periodic interest costs of interest rate swaps previously designated as hedges under GAAP, net — — 39 Ending Balance $ (943 ) $ (345 ) $ (397 )

Equity Incentive Plan (Tables)

Equity Incentive Plan (Tables)	12 Months Ended
	Dec. 31, 2018
Equity Incentive Plan [Abstract]
Share-based Compensation, Performance Shares Award Outstanding Activity [Table Text Block]	2016 Equity Incentive Plan PSUs at Target Performance Level Weighted Average Grant Date Fair Value 1 Unvested balance as of December 31, 2016 — $ — Granted 250,609 $ 19.39 Accrued PSU dividend equivalents 22,767 $ — Vested — $ — Unvested balance as of December 31, 2017 273,376 $ 17.78 Granted 272,228 $ 17.98 Accrued PSU dividend equivalents 61,171 $ — Vested — $ — Unvested balance as of December 31, 2018 606,775 $ 16.08 _______________________ 1. Accrued PSU award dividend equivalents have a weighted average grant date fair value of $0.
Schedule of Share-based Compensation, Restricted Stock Units Award Activity [Table Text Block]	The following table summarizes RSU awards under our 2016 Equity Plan for fiscal years 2018, 2017 and 2016: 2016 Equity Incentive Plan RSU Awards Weighted Average Grant Date Fair Value 1 Weighted Average Vest Date Fair Value Unvested balance as of December 31, 2015 — $ — $ — Granted 101,407 $ 17.89 $ — Accrued RSU dividend equivalents 968 $ — $ — Unvested balance as of December 31, 2016 102,375 $ 17.72 $ — Granted 238,203 $ 19.52 $ — Accrued RSU dividend equivalents 32,498 $ — $ — Vested (37,602 ) $ 16.08 $ 20.42 Forfeitures (246 ) $ 18.29 $ — Unvested balance as of December 31, 2017 335,228 $ 17.46 $ — Granted 2 261,036 $ 18.05 $ — Accrued RSU dividend equivalents 56,618 $ — $ — Vested 2 (150,423 ) $ 16.52 $ 18.60 Forfeitures (546 ) $ 16.98 $ — Unvested balance as of December 31, 2018 501,913 $ 16.08 $ — ________________________________ 1. Accrued RSU award dividend equivalents have a weighted average grant date fair value of $0. 2. Excludes 185,285 of RSU Exchange Awards.
Schedule of Share-based Compensation, Restricted Stock and Restricted Stock Units Activity [Table Text Block]	The following table summarizes RSU and restricted stock transactions under the Director Plan for fiscal years 2017 and 2016: Director Plan Shares of Restricted Stock RSU Awards Weighted Average Grant Date Fair Value 1 Weighted Average Vest Date Fair Value Unvested balance as of December 31, 2015 5,000 31,431 $ 21.44 $ — Granted — 33,015 $ 18.93 $ — Accrued RSU dividend equivalents — 3,527 $ — $ — Vested (5,000 ) (46,538 ) $ 20.00 $ 18.99 Unvested balance as of December 31, 2016 — 21,435 $ 17.49 $ — Accrued RSU dividend equivalents — 1,032 $ — $ — Vested — (22,467 ) $ 16.69 $ 20.15 Unvested balance as of December 31, 2017 — — $ — $ — ________________________________ 1. Accrued RSU award dividend equivalents have a weighted average grant date fair value of $0.

Organization (Details)

Organization (Details)	12 Months Ended
	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Required Annual Distribution of Taxable Net Income	90.00%
Intended annual distribution of taxable net income	100.00%

Summary of Significant Accoun_4

Summary of Significant Accounting Policies (Details) - USD ($) $ in Millions	May 02, 2018	Dec. 31, 2018
Derivative [Line Items]
Gain (Loss) on Contract Termination	$ 42
Document Period End Date		Dec. 31, 2018
Required Annual Distribution of Taxable Net Income		90.00%
Indefinite-lived Intangible Assets, Written off Related to Sale of Business Unit		$ 23

Summary of Significant Accoun_5

Summary of Significant Accounting Policies Goodwill and Intangible Assets (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Goodwill	$ 526	$ 526
Intangible Assets, Net (Excluding Goodwill)		$ 25

Summary of Significant Accoun_6

Summary of Significant Accounting Policies Variable Interest Entities (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Variable Interest Entity [Line Items]
Other Long-term Debt	$ 275	$ 357
Debt Instrument, Description of Variable Rate Basis	LIBOR
Spread Over LIBOR	40	37
Weighted Average Life Other Debt	6 years 1 month 6 days	5 years 8 months 12 days

Investment Securities (Narrativ

Investment Securities (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Debt Securities, Available-for-sale [Line Items]
Document Period End Date	Dec. 31, 2018
Mortgage-backed Securities Available-for-sale, Fair Value Disclosure	$ 84,287	$ 57,080
Weighted average expected constant prepayment rate	8.00%	8.00%
Variable Interest Entity, Consolidated, Carrying Amount, Assets	$ (436)	$ (662)
Debt, at fair value	(275)	(357)
Agency Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Unamortized premium balance	2,900	2,700
TBA securities Fifteen Year and Thirty Year Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Net long TBA position, at fair value	7,300	15,700
TBA, net carrying value	$ 70	$ 3
Credit Risk Transfer Securities [Member] | Minimum [Member]
Debt Securities, Available-for-sale [Line Items]
Weighted Average Coupon Rate	3.90%	3.90%
Underlying Collateral Coupon	3.80%	3.60%
Credit Risk Transfer Securities [Member] | Maximum [Member]
Debt Securities, Available-for-sale [Line Items]
Weighted Average Coupon Rate	9.50%	8.50%
Underlying Collateral Coupon	4.80%	4.40%

Investment Securities (Summary

Investment Securities (Summary of Investment in Agency Security) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Debt Securities, Trading and Available-for-sale, Amortized Cost Basis	$ 85,569	$ 57,466
Document Period End Date	Dec. 31, 2018
Debt Securities, Trading and Available-for-sale	$ 84,287	57,080
Total agency MBS, at fair value	82,727	56,168
Mortgage-backed Securities, Issued by Private Enterprises [Member]
Debt Securities, Trading and Available-for-sale, Amortized Cost Basis	264	7
Debt Securities, Trading and Available-for-sale	266	7
Commercial Mortgage Backed Securities [Member]
Debt Securities, Trading and Available-for-sale, Amortized Cost Basis	280	28
Debt Securities, Trading and Available-for-sale	282	29
Credit Risk Transfer Securities [Member]
Debt Securities, Trading and Available-for-sale, Amortized Cost Basis	1,006	834
Debt Securities, Trading and Available-for-sale	1,012	876
Fixed Income Securities [Member] | Agency Securities [Member]
Debt Securities, Trading and Available-for-sale, Amortized Cost Basis	83,047	55,477
Debt Securities, Trading and Available-for-sale	81,753	55,026
Adjustable-Rate [Member] | Agency Securities [Member]
Debt Securities, Trading and Available-for-sale, Amortized Cost Basis	212	278
Debt Securities, Trading and Available-for-sale	213	283
Collateralized Mortgage Obligations [Member] | Agency Securities [Member]
Debt Securities, Trading and Available-for-sale, Amortized Cost Basis	588	629
Debt Securities, Trading and Available-for-sale	583	631
Interest Only And Principal Only Strip [Member] | Agency Securities [Member]
Debt Securities, Trading and Available-for-sale, Amortized Cost Basis	172	213
Debt Securities, Trading and Available-for-sale	178	228
Agency Securities [Member]
Debt Securities, Trading and Available-for-sale, Amortized Cost Basis	$ 84,019	$ 56,597

Investment Securities (Componen

Investment Securities (Components Of Investment Securities) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Schedule of Investments [Line Items]
Document Period End Date	Dec. 31, 2018
Agency securities transferred to consolidated VIEs	$ 436	$ 662
Debt Securities, Trading	60,692	23,427
Debt Securities, Trading and Available-for-sale	84,287	57,080
Amortized cost	$ 85,569	$ 57,466
Weighted average coupon	3.86%	3.71%
Weighted average yield	3.31%	2.89%
Future Prepayment Rate Assumption Of Investment Portfolio	8.00%	8.00%
Available-for-sale Securities [Member]
Schedule of Investments [Line Items]
Par value	$ 23,295	$ 32,460
Unamortized discount	(12)	(28)
Unamortized premium	1,255	1,566
Amortized cost	24,538	33,998
Gross unrealized gains	7	121
Gross unrealized losses	(950)	(466)
Total available-for-sale securities, at fair value	23,595	33,653
Trading Securities [Member]
Schedule of Investments [Line Items]
Unamortized discount	(103)	(35)
Unamortized premium	1,736	1,159
Debt Securities, Trading, Unrealized Gain	303	71
Debt Securities, Trading, Unrealized Loss	642	112
Trading Securities, Cost	61,031	23,468
Trading Securities Par	59,398	22,344
Fannie Mae [Member]
Schedule of Investments [Line Items]
Debt Securities, Trading	40,267	14,191
Debt Securities, Trading and Available-for-sale	$ 58,078	$ 39,258
Weighted average coupon	3.82%	3.67%
Weighted average yield	3.28%	2.84%
Fannie Mae [Member] | Available-for-sale Securities [Member]
Schedule of Investments [Line Items]
Par value	$ 17,591	$ 24,200
Unamortized discount	(10)	(25)
Unamortized premium	912	1,119
Amortized cost	18,493	25,294
Gross unrealized gains	4	98
Gross unrealized losses	(686)	(325)
Total available-for-sale securities, at fair value	17,811	25,067
Fannie Mae [Member] | Trading Securities [Member]
Schedule of Investments [Line Items]
Unamortized discount	(78)	(34)
Unamortized premium	1,055	711
Debt Securities, Trading, Unrealized Gain	223	26
Debt Securities, Trading, Unrealized Loss	386	70
Trading Securities, Cost	40,430	14,235
Trading Securities Par	39,453	13,558
Freddie Mac [Member]
Schedule of Investments [Line Items]
Debt Securities, Trading	18,871	8,331
Debt Securities, Trading and Available-for-sale	$ 24,623	$ 16,875
Weighted average coupon	3.87%	3.73%
Weighted average yield	3.28%	2.87%
Freddie Mac [Member] | Available-for-sale Securities [Member]
Schedule of Investments [Line Items]
Par value	$ 5,673	$ 8,219
Unamortized discount	(2)	(3)
Unamortized premium	343	447
Amortized cost	6,014	8,663
Gross unrealized gains	2	22
Gross unrealized losses	(264)	(141)
Total available-for-sale securities, at fair value	5,752	8,544
Freddie Mac [Member] | Trading Securities [Member]
Schedule of Investments [Line Items]
Unamortized discount	(9)	0
Unamortized premium	638	415
Debt Securities, Trading, Unrealized Gain	57	2
Debt Securities, Trading, Unrealized Loss	243	42
Trading Securities, Cost	19,057	8,371
Trading Securities Par	18,428	7,956
Ginnie Mae [Member]
Schedule of Investments [Line Items]
Debt Securities, Trading	0	0
Debt Securities, Trading and Available-for-sale	$ 26	$ 35
Weighted average coupon	3.37%	2.84%
Weighted average yield	2.04%	2.02%
Ginnie Mae [Member] | Available-for-sale Securities [Member]
Schedule of Investments [Line Items]
Par value	$ 25	$ 34
Unamortized discount	0	0
Unamortized premium	0	0
Amortized cost	25	34
Gross unrealized gains	1	1
Gross unrealized losses	0	0
Total available-for-sale securities, at fair value	26	35
Ginnie Mae [Member] | Trading Securities [Member]
Schedule of Investments [Line Items]
Unamortized discount	0	0
Unamortized premium	0	0
Debt Securities, Trading, Unrealized Gain	0	0
Debt Securities, Trading, Unrealized Loss	0	0
Trading Securities, Cost	0	0
Trading Securities Par	0	0
Mortgage-backed Securities, Issued by Private Enterprises [Member]
Schedule of Investments [Line Items]
Debt Securities, Trading	260	0
Debt Securities, Trading and Available-for-sale	$ 266	$ 7
Weighted average coupon	3.83%	2.50%
Weighted average yield	4.22%	3.08%
Mortgage-backed Securities, Issued by Private Enterprises [Member] | Available-for-sale Securities [Member]
Schedule of Investments [Line Items]
Par value	$ 6	$ 7
Unamortized discount	0	0
Unamortized premium	0	0
Amortized cost	6	7
Gross unrealized gains	0	0
Gross unrealized losses	0	0
Total available-for-sale securities, at fair value	6	7
Mortgage-backed Securities, Issued by Private Enterprises [Member] | Trading Securities [Member]
Schedule of Investments [Line Items]
Unamortized discount	(10)	0
Unamortized premium	0	0
Debt Securities, Trading, Unrealized Gain	2	0
Debt Securities, Trading, Unrealized Loss	0	0
Trading Securities, Cost	258	0
Trading Securities Par	268	0
Commercial Mortgage Backed Securities [Member]
Schedule of Investments [Line Items]
Debt Securities, Trading	282	29
Debt Securities, Trading and Available-for-sale	$ 282	$ 29
Weighted average coupon	4.58%	6.55%
Weighted average yield	4.68%	7.30%
Commercial Mortgage Backed Securities [Member] | Available-for-sale Securities [Member]
Schedule of Investments [Line Items]
Par value	$ 0	$ 0
Unamortized discount	0	0
Unamortized premium	0	0
Amortized cost	0	0
Gross unrealized gains	0	0
Gross unrealized losses	0	0
Total available-for-sale securities, at fair value	0	0
Commercial Mortgage Backed Securities [Member] | Trading Securities [Member]
Schedule of Investments [Line Items]
Unamortized discount	(6)	(1)
Unamortized premium	5	0
Debt Securities, Trading, Unrealized Gain	3	1
Debt Securities, Trading, Unrealized Loss	1	0
Trading Securities, Cost	280	28
Trading Securities Par	281	29
Credit Risk Transfer Securities [Member]
Schedule of Investments [Line Items]
Debt Securities, Trading	1,012	876
Debt Securities, Trading and Available-for-sale	$ 1,012	$ 876
Weighted average coupon	5.86%	5.26%
Weighted average yield	5.16%	5.19%
Credit Risk Transfer Securities [Member] | Available-for-sale Securities [Member]
Schedule of Investments [Line Items]
Par value	$ 0	$ 0
Unamortized discount	0	0
Unamortized premium	0	0
Amortized cost	0	0
Gross unrealized gains	0	0
Gross unrealized losses	0	0
Total available-for-sale securities, at fair value	0	0
Credit Risk Transfer Securities [Member] | Trading Securities [Member]
Schedule of Investments [Line Items]
Unamortized discount	0	0
Unamortized premium	38	33
Debt Securities, Trading, Unrealized Gain	18	42
Debt Securities, Trading, Unrealized Loss	12	0
Trading Securities, Cost	1,006	834
Trading Securities Par	968	801
Credit Risk Transfer Securities [Member] | Securities Remeasured at Fair Value [Member]
Schedule of Investments [Line Items]
Debt Securities, Trading and Available-for-sale	$ 1,012	$ 876

Investment Securities (Summar_2

Investment Securities (Summary Of Agency Securities Estimated Weighted Average Life Classifications) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Document Period End Date	Dec. 31, 2018
Agency securities classified as available for sale, Fair value	$ 84,287	$ 57,080
Agency securities classified as available for sale, Amortized cost	$ 85,569	$ 57,466
Weighted Average Coupon	3.86%	3.71%
Weighted Average Yield	3.31%	2.89%
Greater Than One Year and Less Than or Equal to Three Years [Member]
Fair Value	$ 1,690	$ 2,712
Amortized Cost	$ 1,716	$ 2,693
Weighted Average Coupon	3.99%	3.90%
Weighted Average Yield	2.64%	2.67%
Greater Than Three Years and Less Than or Equal to Five Years [Member]
Fair Value	$ 5,518	$ 7,499
Amortized Cost	$ 5,586	$ 7,518
Weighted Average Coupon	3.35%	3.31%
Weighted Average Yield	2.73%	2.39%
Greater Than Five Years [Member]
Fair Value	$ 72,503	$ 45,977
Amortized Cost	$ 73,588	$ 46,398
Weighted Average Coupon	3.92%	3.75%
Weighted Average Yield	3.37%	2.95%
Greater Than Ten Years [Member]
Fair Value	$ 4,576	$ 892
Amortized Cost	$ 4,679	$ 857
Weighted Average Coupon	3.57%	4.87%
Weighted Average Yield	3.30%	4.74%

Investment Securities (Summar_3

Investment Securities (Summary Of Changes In Accumulated OCI For Available-For-Sale Security) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Unrealized Gains and (Losses), Net	$ 361	$ (193)	$ (145)	$ (621)	$ (205)	$ 90	$ 121	$ 46	$ (598)	$ 52	$ (370)
Agency Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning OCI Balance				$ (345)				$ (397)	(345)	(397)	(66)
Unrealized Gains and (Losses), Net									(677)	(31)	(261)
Reversal of Unrealized (Gains) and Losses, Net on Realization									79	83	(109)
Ending OCI Balance	$ (943)				$ (345)				$ (943)	$ (345)	$ (397)

Investment Securities (Summar_4

Investment Securities (Summary Of Continuous Unrealized Loss Positions Of Available-For-Sale Security) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Document Period End Date	Dec. 31, 2018
Accumulated Other Comprehensive Income (Loss) [Member]
Unrealized Loss Position For - Estimated Fair Value - Less than 12 Months	$ 4,783	$ 3,582
Unrealized Loss Position For - Unrealized Loss - Less than 12 Months	(72)	(15)
Unrealized Loss Position For - Estimated Fair Value - 12 Months or More	18,231	20,577
Unrealized Loss Position For - Unrealized Loss - 12 Months or More	(878)	(451)
Unrealized Loss Position For - Estimated Fair Value - Total	23,014	24,159
Unrealized Loss Position For - Unrealized Loss - Total	$ (950)	$ (466)

Investment Securities (Summar_5

Investment Securities (Summary Of Net Gain From Sale Of Agency Securities) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cost of Sale of Fair Value Option Securities									$ (5,344)	$ (12,913)	$ 0
Cost of Sale of Investment Securities									(9,650)	(19,237)	(17,907)
Proceeds from agency MBS sold									21,308	14,557	10,393
Net gain (loss) on sale of investment securities	$ (21)	$ (40)	$ (74)	$ (2)	$ (16)	$ 22	$ 15	$ (84)	(137)	(63)	109
Available-for-sale Securities [Member]
Agency MBS sold, at cost									(4,306)	(6,324)	(17,907)
Proceeds from agency MBS sold									4,227	6,241	18,016
Net gain (loss) on sale of investment securities										(83)	109
Gross gain on sale of investment securities									6	16	123
Gross loss on sale of investment securities									(85)	(99)	(14)
Securities Remeasured at Fair Value [Member]
Proceeds from agency MBS sold									5,286	12,933	0
Net gain (loss) on sale of investment securities										20	0
Gross gain on sale of investment securities									16	48	0
Gross loss on sale of investment securities									(74)	(28)	0
Securities (Assets) [Member]
Proceeds from agency MBS sold									9,513	19,174	18,016
Net gain (loss) on sale of investment securities									(137)	(63)	109
Gross gain on sale of investment securities									22	64	123
Gross loss on sale of investment securities									(159)	$ (127)	$ (14)
Cost and Proceeds of Investment Securities [Member] | Available-for-sale Securities [Member]
Net gain (loss) on sale of investment securities									(79)
Cost and Proceeds of Investment Securities [Member] | Securities Remeasured at Fair Value [Member]
Net gain (loss) on sale of investment securities									(58)
Gross Gain & Loss of Investment Securities [Member] | Available-for-sale Securities [Member]
Net gain (loss) on sale of investment securities									(79)
Gross Gain & Loss of Investment Securities [Member] | Securities Remeasured at Fair Value [Member]
Net gain (loss) on sale of investment securities									$ (58)

Investment Securities Securitie

Investment Securities Securities by Credit Rating (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Debt Securities, Available-for-sale [Line Items]
Document Period End Date	Dec. 31, 2018
Debt Securities, Trading	$ 60,692	$ 23,427
Debt Securities, Trading and Available-for-sale	84,287	57,080
Mortgage-backed Securities, Issued by Private Enterprises [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Trading	260	0
Debt Securities, Trading and Available-for-sale	266	7
Commercial Mortgage Backed Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Trading	282	29
Debt Securities, Trading and Available-for-sale	282	29
Credit Risk Transfer Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Trading	1,012	876
Debt Securities, Trading and Available-for-sale	1,012	876
Securities Remeasured at Fair Value [Member] | Credit Risk Transfer Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Trading and Available-for-sale	1,012	876
BBB Rating [Member] | Mortgage-backed Securities, Issued by Private Enterprises [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Trading	43	0
BBB Rating [Member] | Commercial Mortgage Backed Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Trading	53	29
BBB Rating [Member] | Credit Risk Transfer Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Trading	25	34
BB Rating [Member] | Mortgage-backed Securities, Issued by Private Enterprises [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Trading	8	0
BB Rating [Member] | Commercial Mortgage Backed Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Trading	10	0
BB Rating [Member] | Credit Risk Transfer Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Trading	492	370
AAA Rating [Member] | Mortgage-backed Securities, Issued by Private Enterprises [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Trading	160	7
AAA Rating [Member] | Commercial Mortgage Backed Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Trading	52	0
AAA Rating [Member] | Credit Risk Transfer Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Trading	0	0
AA Rating [Member] | Mortgage-backed Securities, Issued by Private Enterprises [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Trading	17	0
AA Rating [Member] | Commercial Mortgage Backed Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Trading	152	0
AA Rating [Member] | Credit Risk Transfer Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Trading	0	0
A Rating [Member] | Mortgage-backed Securities, Issued by Private Enterprises [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Trading	33	0
A Rating [Member] | Commercial Mortgage Backed Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Trading	15	0
A Rating [Member] | Credit Risk Transfer Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Trading	17	1
B Rating [Member] | Mortgage-backed Securities, Issued by Private Enterprises [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Trading	2	0
B Rating [Member] | Commercial Mortgage Backed Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Trading	0	0
B Rating [Member] | Credit Risk Transfer Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Trading	453	455
Not Rated [Member] | Mortgage-backed Securities, Issued by Private Enterprises [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Trading	3	0
Not Rated [Member] | Commercial Mortgage Backed Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Trading	0	0
Not Rated [Member] | Credit Risk Transfer Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Trading	$ 25	$ 16

Repurchase Agreements And Rev_3

Repurchase Agreements And Reverse Repurchase Agreements (Narrative) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018USD ($)days	Dec. 31, 2017USD ($)
Assets Sold under Agreements to Repurchase [Line Items]
Document Period End Date	Dec. 31, 2018
Receivable Under Reverse Repurchase Agreements	$ 21,813	$ 10,961
Securities Sold under Agreements to Repurchase	75,717	50,296
Obligation to Return Securities Borrowed Under Reverse Repurchase Agreements at Fair Value	$ 21,431	$ 10,467
Short-term Debt, Weighted Average Interest Rate, at Point in Time	2.79%	1.57%
Debt of consolidated variable interest entities, at fair value	$ (275)	$ (357)
Description of variable rate basis	LIBOR
Basis spread over LIBOR	40	37
Weighted average life of other debt	6 years 1 month 6 days	5 years 8 months 12 days
TBA securities Fifteen Year and Thirty Year Securities [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Derivative, Fair Value, Net	$ 70	$ 3
TBA and Forward Settling Agency Securities [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Derivative, Forward Settlement Value	7,252	15,739
Derivative, Fair Value, Net	70	$ 3
Forward Contracts [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Securities Sold under Agreements to Repurchase	$ 10,700
Weighted Average Forward Start Days | days	9
Short-term Debt, Weighted Average Interest Rate, at Point in Time	2.90%
Bethesda Securities [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Percentage of Repurchase Agreement Funding	35.00%	33.00%
FICC [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Percentage of Repurchase Agreement Funding	33.00%	30.00%
Obligation to Return Securities Borrowed Under Reverse Repurchase Agreements at Fair Value	$ 4,489	$ 2,698

Repurchase Agreements And Other

Repurchase Agreements And Other Debt (Repurchase Arrangements And Weighted Average Interest Rates Classified By Original Maturities) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018USD ($)days	Dec. 31, 2017USD ($)days
Document Period End Date	Dec. 31, 2018
Repurchase Agreements	$ 75,717	$ 50,296
Weighted Average Interest Rate	2.79%	1.57%
Weighted Average Days to Maturity | days	49	116
Obligation to Return Securities Borrowed Under Reverse Repurchase Agreements at Fair Value	$ 21,431	$ 10,467
Maturity Overnight [Member]
Repurchase Agreements	19,450	5,250
30 Days or Less [Member]
Repurchase Agreements	$ 48,533	$ 19,771
Weighted Average Interest Rate	2.88%	1.59%
Weighted Average Days to Maturity | days	9	11
1 to 3 Months
Repurchase Agreements	$ 20,991	$ 16,150
Weighted Average Interest Rate	2.57%	1.50%
Weighted Average Days to Maturity | days	56	50
3 to 6 Months
Repurchase Agreements	$ 2,218	$ 7,287
Weighted Average Interest Rate	2.65%	1.50%
Weighted Average Days to Maturity | days	167	130
6 to 9 Months
Repurchase Agreements	$ 200	$ 2,361
Weighted Average Interest Rate	3.19%	1.66%
Weighted Average Days to Maturity | days	208	225
9 to 12 Months
Repurchase Agreements	$ 950	$ 202
Weighted Average Interest Rate	2.80%	1.64%
Weighted Average Days to Maturity | days	279	297
12 to 24 Months
Repurchase Agreements	$ 2,200	$ 1,700
Weighted Average Interest Rate	2.91%	1.84%
Weighted Average Days to Maturity | days	438	468
24 to 36 Months
Repurchase Agreements	$ 625	$ 2,200
Weighted Average Interest Rate	3.11%	1.80%
Weighted Average Days to Maturity | days	776	803
36 to 48 months
Repurchase Agreements	$ 0	$ 625
Weighted Average Interest Rate	0.00%	1.90%
Weighted Average Days to Maturity | days	0	1,141
FICC [Member]
Obligation to Return Securities Borrowed Under Reverse Repurchase Agreements at Fair Value	$ 4,489	$ 2,698

Derivative and Other Hedging _3

Derivative and Other Hedging Instruments (Narrative) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018USD ($)month	Dec. 31, 2017USD ($)month	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Interest Rate Swaption [Member]
Average Maturity (Years)	7 years 4 months 24 days	8 years 10 months 24 days
Cash Flow Hedges Derivative Instruments Not Designated As Hedging Instruments Average Months To Expiration | month	6	10
Notional Amount	$ 3,500	$ 6,650
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	90	(66)	$ (3)
Notional Amount Of Derivatives Not Designated As Hedging Instruments Additions During The Period	1,250	6,450	500
Notional Amount Of Derivatives Not Designated As Hedging Instruments Settlement Expiration During The Period	$ (4,400)	$ (1,000)	(1,450)
Derivative, Average Fixed Interest Rate	2.93%	2.72%
Interest Rate Derivatives, at Fair Value, Net	$ 37	$ 75
Options At Cost	98	159
TBA and Forward Settling Agency Securities [Member]
Notional Amount	7,152	15,474	10,916	$ 7,295
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	(299)	330	(59)
Notional Amount Of Derivatives Not Designated As Hedging Instruments Additions During The Period	194,534	237,601	116,439
Notional Amount Of Derivatives Not Designated As Hedging Instruments Settlement Expiration During The Period		(233,043)	(112,818)
US Treasury Securities [Member]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	48	0	(5)
Unrealized gain on derivative instruments, net	0	0	39
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	(181)	191	(323)
Not Designated as Hedging Instrument [Member] | Interest Rate Swaption [Member]
Notional Amount	3,500
Short [Member] | US Treasury Securities [Member]
Notional Amount	21,345	10,699	8,061	1,714
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	(161)	(141)	7
Notional Amount Of Derivatives Not Designated As Hedging Instruments Additions During The Period	(19,278)	14,030	9,884
Notional Amount Of Derivatives Not Designated As Hedging Instruments Settlement Expiration During The Period	8,632	(11,392)	(3,537)
Long [Member] | US Treasury Securities [Member]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	1	1	134
Trading Securities Added During the Period	1,949	404	961
Notional Amount Of Trading Securities Settlement Expiration During The Period	(1,904)	(593)	(797)
Debt Securities, Trading, and Equity Securities, FV-NI		$ 0	$ 189	$ 25
Long [Member]
Debt Securities, Trading, and Equity Securities, FV-NI	$ 45

Derivative and Other Hedging _4

Derivative and Other Hedging Instruments (Fair Value Information) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Derivative [Line Items]
Derivative asset, fair value	$ 273	$ 205
Derivative liability, fair value	(84)	(28)
Derivative assets, at fair value	273	205
Derivative Liability	(84)	(28)
U.S. Treasury securities	46	0
U.S. Treasury Securities - short	(21,431)	(10,467)
Total - (short)/long, net	(21,385)	(10,467)
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	(181)	191	$ (323)
TBA and Forward Settling Agency Securities [Member]
Derivative [Line Items]
Derivative Liability, Notional Amount	7,152	15,474	10,916	$ 7,295
Notional Amount Of Derivatives Not Designated As Hedging Instruments Additions During The Period	194,534	237,601	116,439
Notional Amount Of Derivatives Not Designated As Hedging Instruments Settlement Expiration During The Period		(233,043)	(112,818)
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	(299)	330	(59)
Interest Rate Swap [Member]
Derivative [Line Items]
Derivative Liability, Notional Amount	51,625	43,700
Derivative liability, fair value	0	(1)
Notional Amount Of Derivatives Not Designated As Hedging Instruments Additions During The Period	14,350	14,825	15,650
Notional Amount Of Derivatives Not Designated As Hedging Instruments Settlement Expiration During The Period	(6,425)	(8,300)	(19,000)
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	140	67	(397)
Interest Rate Swap [Member] | Fair Value, Inputs, Level 2 [Member]
Derivative [Line Items]
Derivative asset, fair value	126	81
Interest Rate Swaption [Member]
Derivative [Line Items]
Derivative Liability, Notional Amount	3,500	6,650
Notional Amount Of Derivatives Not Designated As Hedging Instruments Additions During The Period	1,250	6,450	500
Notional Amount Of Derivatives Not Designated As Hedging Instruments Settlement Expiration During The Period	(4,400)	(1,000)	(1,450)
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	90	(66)	(3)
Interest Rate Swaption [Member] | Fair Value, Inputs, Level 2 [Member]
Derivative [Line Items]
Derivative asset, fair value	37	75
Purchases Of TBAs And Forward Settling Agency Securities [Member]
Derivative [Line Items]
Derivative liability, fair value	(40)	(27)
Notional Amount Of Derivatives Not Designated As Hedging Instruments Settlement Expiration During The Period	(202,856)
US Treasury Securities [Member]
Derivative [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	48	0	(5)
US Treasury Securities [Member] | Fair Value, Measurements, Recurring [Member] | Future [Member] | Fair Value, Inputs, Level 1 [Member]
Derivative [Line Items]
Derivative assets, at fair value	0	19
Derivative Liability	44	0
TBA and Forward Settling Agency Securities [Member] | Fair Value, Measurements, Recurring [Member] | Purchases Of TBAs And Forward Settling Agency Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Derivative [Line Items]
Derivative assets, at fair value	110	30
Not Designated as Hedging Instrument [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Derivative Liability, Notional Amount	51,625
Not Designated as Hedging Instrument [Member] | Interest Rate Swaption [Member]
Derivative [Line Items]
Derivative Liability, Notional Amount	3,500
Short [Member] | US Treasury Securities [Member]
Derivative [Line Items]
Derivative Liability, Notional Amount	21,345	10,699	8,061	1,714
Notional Amount Of Derivatives Not Designated As Hedging Instruments Additions During The Period	(19,278)	14,030	9,884
Notional Amount Of Derivatives Not Designated As Hedging Instruments Settlement Expiration During The Period	8,632	(11,392)	(3,537)
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	(161)	(141)	7
Long [Member]
Derivative [Line Items]
Debt Securities, Trading, and Equity Securities, FV-NI	45
Long [Member] | US Treasury Securities [Member]
Derivative [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	1	1	134
Debt Securities, Trading, and Equity Securities, FV-NI		0	189	$ 25
Trading Securities Added During the Period	1,949	404	961
Notional Amount Of Trading Securities Settlement Expiration During The Period	$ (1,904)	$ (593)	$ (797)

Derivative and Other Hedging _5

Derivative and Other Hedging Instruments (Summary Of Outstanding Interest Rate Swaps) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018USD ($)month	Dec. 31, 2017USD ($)month	Dec. 31, 2016USD ($)
Document Period End Date	Dec. 31, 2018
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	$ (181)	$ 191	$ (323)
Payer Swaption [Member]
Interest Rate Derivative Not Designated As Hedging Instruments Receive Rate	3M	3M
Interest Rate Swaption [Member]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	$ 90	$ (66)	(3)
Notional Amount	$ 3,500	$ 6,650
Average Fixed Pay Rate	2.93%	2.72%
Options At Cost	$ 98	$ 159
Interest Rate Derivatives, at Fair Value, Net	$ 37	$ 75
Cash Flow Hedges Derivative Instruments Not Designated As Hedging Instruments Average Months To Expiration | month	6	10
Average Maturity (Years)	7 years 4 months 24 days	8 years 10 months 24 days
Forward Contracts [Member] | Interest Rate Swap [Member]
Derivative, Notional Amount	$ 5,700	$ 4,600
Weighted Average Forward Start Date	6 months	3 months 18 days
Interest Rate Swap [Member]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	$ 140	$ 67	$ (397)
Notional Amount	$ 51,625	$ 43,700
Average Fixed Pay Rate	2.11%	1.74%
Average Receive Rate	2.63%	1.44%
Average Maturity (Years)	5 years	4 years 6 months
Less Than or Equal to One Year [Member] | Payer Swaption [Member]
Interest Rate Derivative Not Designated As Hedging Instruments Receive Rate	3M	3M
Less Than or Equal to One Year [Member] | Interest Rate Swaption [Member]
Notional Amount	$ 3,000	$ 5,100
Average Fixed Pay Rate	2.96%	2.71%
Options At Cost	$ 80	$ 118
Interest Rate Derivatives, at Fair Value, Net	$ 23	$ 46
Cash Flow Hedges Derivative Instruments Not Designated As Hedging Instruments Average Months To Expiration | month	4	7
Average Maturity (Years)	7 years	8 years 9 months 18 days
Greater Than One Year and Less Than or Equal to Two 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 Two Years [Member] | Interest Rate Swaption [Member]
Notional Amount	$ 500	$ 1,050
Average Fixed Pay Rate	2.78%	2.71%
Options At Cost	$ 18	$ 23
Interest Rate Derivatives, at Fair Value, Net	$ 14	$ 16
Cash Flow Hedges Derivative Instruments Not Designated As Hedging Instruments Average Months To Expiration | month	18	18
Average Maturity (Years)	10 years	8 years 8 months 12 days
Greater Than Two Years and Less Than or Equal to Three Years [Member] | Payer Swaption [Member]
Interest Rate Derivative Not Designated As Hedging Instruments Receive Rate		3M
Greater Than Two Years and Less Than or Equal to Three Years [Member] | Interest Rate Swaption [Member]
Notional Amount		$ 500
Average Fixed Pay Rate		2.78%
Options At Cost		$ 18
Interest Rate Derivatives, at Fair Value, Net		$ 13
Cash Flow Hedges Derivative Instruments Not Designated As Hedging Instruments Average Months To Expiration | month		30
Average Maturity (Years)		10 years
Greater Than One Year and Less Than or Equal to Three Years [Member] | Interest Rate Swap [Member]
Notional Amount	$ 19,900	$ 21,025
Average Fixed Pay Rate	1.63%	1.40%
Average Receive Rate	2.62%	1.46%
Average Maturity (Years)	1 year 3 months 18 days	1 year 6 months
Greater Than Three Years and Less Than or Equal to Five Years [Member] | Interest Rate Swap [Member]
Notional Amount	$ 8,425	$ 6,825
Average Fixed Pay Rate	2.06%	1.82%
Average Receive Rate	2.61%	1.43%
Average Maturity (Years)	4 years	4 years 1 month 6 days
Greater Than Five Years and Less than or Equal to Seven Years [Member] | Interest Rate Swap [Member]
Notional Amount	$ 7,875	$ 5,775
Average Fixed Pay Rate	2.66%	2.02%
Average Receive Rate	2.66%	1.44%
Average Maturity (Years)	6 years 1 month 6 days	5 years 10 months 24 days
Greater Than Seven Years and Less than or Equal to Ten Years [Member] | Interest Rate Swap [Member]
Notional Amount	$ 10,550	$ 6,650
Average Fixed Pay Rate	2.36%	2.10%
Average Receive Rate	2.64%	1.42%
Average Maturity (Years)	8 years 9 months 18 days	9 years 1 month 6 days
Greater Than Ten Years [Member] | Interest Rate Swap [Member]
Notional Amount	$ 4,875	$ 3,425
Average Fixed Pay Rate	2.77%	2.49%
Average Receive Rate	2.63%	1.45%
Average Maturity (Years)	11 years 7 months 6 days	12 years 10 months 24 days

Derivative and Other Hedging _6

Derivative and Other Hedging Instruments (Remaining Interest Rate Swap Term) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018USD ($)month	Dec. 31, 2017USD ($)month	Dec. 31, 2016USD ($)
Document Period End Date	Dec. 31, 2018
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	$ (181)	$ 191	$ (323)
Interest Rate Swaption [Member]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	90	(66)	(3)
Cost	98	159
Fair Value	$ 37	$ 75
Average Months to Expiration | month	6	10
Derivative Liability, Notional Amount	$ 3,500	$ 6,650
Average Fixed Pay Rate	2.93%	2.72%
Average Maturity (Years)	7 years 4 months 24 days	8 years 10 months 24 days
Payer Swaption [Member]
Average Receive Rate (LIBOR)	3M	3M
Interest Rate Swap [Member]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	$ 140	$ 67	$ (397)
Derivative Liability, Notional Amount	$ 51,625	$ 43,700
Average Fixed Pay Rate	2.11%	1.74%
Average Maturity (Years)	5 years	4 years 6 months
Less Than or Equal to One Year [Member] | Interest Rate Swaption [Member]
Cost	$ 80	$ 118
Fair Value	$ 23	$ 46
Average Months to Expiration | month	4	7
Derivative Liability, Notional Amount	$ 3,000	$ 5,100
Average Fixed Pay Rate	2.96%	2.71%
Average Maturity (Years)	7 years	8 years 9 months 18 days
Less Than or Equal to One Year [Member] | Payer Swaption [Member]
Average Receive Rate (LIBOR)	3M	3M
Greater Than One Year and Less Than or Equal to Three Years [Member] | Interest Rate Swap [Member]
Derivative Liability, Notional Amount	$ 19,900	$ 21,025
Average Fixed Pay Rate	1.63%	1.40%
Average Maturity (Years)	1 year 3 months 18 days	1 year 6 months
Bermudan [Member] | Interest Rate Swaption [Member]
Derivative Liability, Notional Amount	$ 700
Interest Rate Swaps Excluding Forward Starting [Member] | Interest Rate Swap [Member]
Average Fixed Pay Rate	1.98%	1.68%

Derivative and Other Hedging _7

Derivative and Other Hedging Instruments (US Treasury Securities) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Derivative [Line Items]
Document Period End Date	Dec. 31, 2018
U.S. Treasury securities, net	$ (21,385)	$ (10,467)
Weighted Average Yield Percentage	3.31%	2.89%
7 Years Maturity [Member]
Derivative [Line Items]
U.S. Treasury securities, net	$ (14,357)	$ (6,131)
At Par Value [Member]
Derivative [Line Items]
U.S. Treasury securities, net	(21,300)	(10,699)
US Treasury Securities [Member]
Derivative [Line Items]
Derivative, Fair Value, Net	(44)	19
TBA and Forward Settling Agency Securities [Member]
Derivative [Line Items]
Derivative, Notional Amount	(7,152)	(15,474)
Derivative, Forward Settlement Value	(7,252)	(15,739)
Derivative Asset, Fair Value, Gross Asset	(7,322)	(15,742)
Derivative, Fair Value, Net	70	3
5 Year Maturity [Member]
Derivative [Line Items]
U.S. Treasury securities, net	(703)	(288)
10 Year Maturity [Member]
Derivative [Line Items]
U.S. Treasury securities, net	(6,240)	(4,280)
10 Year Maturity [Member] | US Treasury Securities [Member]
Derivative [Line Items]
Derivative, Fair Value, Net	(44)	15
5 Year Maturity [Member] | US Treasury Securities [Member]
Derivative [Line Items]
Derivative, Fair Value, Net	0	4
Short [Member] | US Treasury Securities [Member]
Derivative [Line Items]
Derivative, Notional Amount	(1,650)	(2,910)
Derivative, Forward Settlement Value	(1,969)	(3,570)
Derivative Asset, Fair Value, Gross Asset	(2,013)	(3,551)
Short [Member] | 10 Year Maturity [Member] | US Treasury Securities [Member]
Derivative [Line Items]
Derivative, Notional Amount	(1,650)	(2,180)
Derivative, Forward Settlement Value	(1,969)	(2,718)
Derivative Asset, Fair Value, Gross Asset	(2,013)	(2,703)
Short [Member] | 5 Year Maturity [Member] | US Treasury Securities [Member]
Derivative [Line Items]
Derivative, Notional Amount	0	(730)
Derivative, Forward Settlement Value	0	(852)
Derivative Asset, Fair Value, Gross Asset	0	(848)
Fair Value Hedging [Member]
Derivative [Line Items]
U.S. Treasury securities, net	(21,385)	(10,467)
Fair Value Hedging [Member] | 7 Years Maturity [Member]
Derivative [Line Items]
U.S. Treasury securities, net	(14,410)	(6,029)
Fair Value Hedging [Member] | 5 Year Maturity [Member]
Derivative [Line Items]
U.S. Treasury securities, net	(713)	(283)
Fair Value Hedging [Member] | 10 Year Maturity [Member]
Derivative [Line Items]
U.S. Treasury securities, net	(6,262)	(4,155)
At Cost Basis [Member]
Derivative [Line Items]
U.S. Treasury securities, net	(21,255)	(10,622)
At Cost Basis [Member] | 7 Years Maturity [Member]
Derivative [Line Items]
U.S. Treasury securities, net	(14,325)	(6,106)
At Cost Basis [Member] | 5 Year Maturity [Member]
Derivative [Line Items]
U.S. Treasury securities, net	(706)	(286)
At Cost Basis [Member] | 10 Year Maturity [Member]
Derivative [Line Items]
U.S. Treasury securities, net	$ (6,224)	$ (4,230)
US Treasury Securities [Member]
Derivative [Line Items]
Weighted Average Yield Percentage	2.66%	2.12%

Derivative and Other Hedging _8

Derivative and Other Hedging Instruments (TBA Securities by Coupon and Issuer) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Derivative [Line Items]
Document Period End Date	Dec. 31, 2018
TBA and Forward Settling Agency Securities [Member]
Derivative [Line Items]
Derivative, Notional Amount	$ (7,152)	$ (15,474)
Cost Basis	(7,252)	(15,739)
Net long TBA position, at fair value	(7,322)	(15,742)
TBA, net carrying value	70	3
30 Year Maturity [Member] | TBA and Forward Settling Agency Securities [Member]
Derivative [Line Items]
Derivative, Notional Amount	(3,529)	(10,526)
Cost Basis	(3,617)	(10,714)
Net long TBA position, at fair value	(3,649)	(10,727)
TBA, net carrying value	32	13
30 Year Maturity [Member] | 3.0% Coupon [Member] | TBA and Forward Settling Agency Securities [Member]
Derivative [Line Items]
Derivative, Notional Amount	(1,028)	(4,317)
Cost Basis	(981)	(4,303)
Net long TBA position, at fair value	(1,003)	(4,312)
TBA, net carrying value	22	9
30 Year Maturity [Member] | 3.5% Coupon [Member] | TBA and Forward Settling Agency Securities [Member]
Derivative [Line Items]
Derivative, Notional Amount		(3,932)
Cost Basis		(4,027)
Net long TBA position, at fair value		(4,034)
TBA, net carrying value	(34)	7
30 Year Maturity [Member] | 4.0% Coupon [Member] | TBA and Forward Settling Agency Securities [Member]
Derivative [Line Items]
Derivative, Notional Amount	(3,030)	(2,338)
Cost Basis	(3,073)	(2,449)
Net long TBA position, at fair value	(3,089)	(2,446)
TBA, net carrying value	16	(3)
30 Year Maturity [Member] | 4.5% Coupon [Member] | TBA and Forward Settling Agency Securities [Member]
Derivative [Line Items]
Derivative, Notional Amount	(2,450)
Cost Basis	(2,506)
Net long TBA position, at fair value	(2,534)
TBA, net carrying value	28	0
30 Year Maturity [Member] | Short [Member] | 3.5% Coupon [Member] | TBA and Forward Settling Agency Securities [Member]
Derivative [Line Items]
Derivative, Notional Amount	(2,979)
Cost Basis	(2,943)
Net long TBA position, at fair value	(2,977)
30 Year Maturity [Member] | Short [Member] | 4.5% Coupon [Member] | TBA and Forward Settling Agency Securities [Member]
Derivative [Line Items]
Derivative, Notional Amount		(61)
Cost Basis		(65)
Net long TBA position, at fair value		(65)
15 Year Maturity [Member] | TBA and Forward Settling Agency Securities [Member]
Derivative [Line Items]
Derivative, Notional Amount	(3,623)	(4,948)
Cost Basis	(3,635)	(5,025)
Net long TBA position, at fair value	(3,673)	(5,015)
TBA, net carrying value	38	(10)
15 Year Maturity [Member] | 2.5% Coupon [Member] | TBA and Forward Settling Agency Securities [Member]
Derivative [Line Items]
Derivative, Notional Amount	0	(1,373)
Cost Basis	0	(1,372)
Net long TBA position, at fair value	0	(1,370)
TBA, net carrying value	0	(2)
15 Year Maturity [Member] | 3.0% Coupon [Member] | TBA and Forward Settling Agency Securities [Member]
Derivative [Line Items]
Derivative, Notional Amount	(567)	(3,161)
Cost Basis	(557)	(3,225)
Net long TBA position, at fair value	(566)	(3,217)
TBA, net carrying value	9	(8)
15 Year Maturity [Member] | 3.5% Coupon [Member] | TBA and Forward Settling Agency Securities [Member]
Derivative [Line Items]
Derivative, Notional Amount	(1,706)	(414)
Cost Basis	(1,708)	(428)
Net long TBA position, at fair value	(1,726)	(428)
TBA, net carrying value	18	0
15 Year Maturity [Member] | 4.0% Coupon [Member] | TBA and Forward Settling Agency Securities [Member]
Derivative [Line Items]
Derivative, Notional Amount	(1,350)	0
Cost Basis	(1,370)	0
Net long TBA position, at fair value	(1,381)	0
TBA, net carrying value	$ 11	$ 0

Derivative and Other Hedging _9

Derivative and Other Hedging Instruments (Effect Of Derivative Instruments Not Designated As Hedges On Comprehensive Income Statement) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Changes in Derivative and Other Hedge Portfolio [Roll Forward]
Amount Gain/(Loss) Recognized in Income on Derivatives	$ (181)	$ 191	$ (323)
Interest Rate Swaption [Member]
Changes in Derivative and Other Hedge Portfolio [Roll Forward]
Notional Amount	(6,650)
Additions	(1,250)	(6,450)	(500)
Settlement, Expirations or Exercise	4,400	1,000	1,450
Notional Amount	(3,500)	(6,650)
Amount Gain/(Loss) Recognized in Income on Derivatives	90	(66)	(3)
TBA and Forward Settling Agency Securities [Member]
Changes in Derivative and Other Hedge Portfolio [Roll Forward]
Notional Amount	(15,474)	(10,916)	(7,295)
Additions	(194,534)	(237,601)	(116,439)
Settlement, Expirations or Exercise		233,043	112,818
Notional Amount	(7,152)	(15,474)	(10,916)
Amount Gain/(Loss) Recognized in Income on Derivatives	(299)	330	(59)
Derivative, Notional Amount	(7,152)	(15,474)
Purchases Of TBAs And Forward Settling Agency Securities [Member]
Changes in Derivative and Other Hedge Portfolio [Roll Forward]
Settlement, Expirations or Exercise	202,856
Interest Rate Swap [Member]
Changes in Derivative and Other Hedge Portfolio [Roll Forward]
Notional Amount	(43,700)
Additions	(14,350)	(14,825)	(15,650)
Settlement, Expirations or Exercise	6,425	8,300	19,000
Notional Amount	(51,625)	(43,700)
Amount Gain/(Loss) Recognized in Income on Derivatives	140	67	(397)
US Treasury Securities [Member]
Changes in Derivative and Other Hedge Portfolio [Roll Forward]
Amount Gain/(Loss) Recognized in Income on Derivatives	48	0	(5)
Not Designated as Hedging Instrument [Member] | Interest Rate Swaption [Member]
Changes in Derivative and Other Hedge Portfolio [Roll Forward]
Notional Amount	(3,500)
Derivative, Notional Amount		(6,650)	(1,200)	$ (2,150)
Not Designated as Hedging Instrument [Member] | Interest Rate Swap [Member]
Changes in Derivative and Other Hedge Portfolio [Roll Forward]
Notional Amount	(51,625)
Derivative, Notional Amount		(43,700)	(37,175)	(40,525)
Short [Member] | US Treasury Securities [Member]
Changes in Derivative and Other Hedge Portfolio [Roll Forward]
Notional Amount	(10,699)	(8,061)	(1,714)
Additions	19,278	(14,030)	(9,884)
Settlement, Expirations or Exercise	(8,632)	11,392	3,537
Notional Amount	(21,345)	(10,699)	(8,061)
Amount Gain/(Loss) Recognized in Income on Derivatives	(161)	(141)	7
Derivative, Notional Amount	(1,650)	(2,910)
Long [Member]
Changes in Derivative and Other Hedge Portfolio [Roll Forward]
Debt Securities, Trading, and Equity Securities, FV-NI	45
Long [Member] | US Treasury Securities [Member]
Changes in Derivative and Other Hedge Portfolio [Roll Forward]
Amount Gain/(Loss) Recognized in Income on Derivatives	1	1	134
Debt Securities, Trading, and Equity Securities, FV-NI		0	189	$ 25
Trading Securities Added During the Period	1,949	404	961
Notional Amount Of Trading Securities Settlement Expiration During The Period	(1,904)	(593)	(797)
Future [Member] | Short [Member] | US Treasury Securities [Member]
Changes in Derivative and Other Hedge Portfolio [Roll Forward]
Notional Amount	(2,910)	(1,810)	(1,860)
Additions	7,859	(11,340)	(7,840)
Settlement, Expirations or Exercise	(9,119)	10,240	7,890
Notional Amount	$ (1,650)	$ (2,910)	$ (1,810)

Pledged Assets (Narrative) (Det

Pledged Assets (Narrative) (Details)	Dec. 31, 2018
Pledged Assets [Abstract]
Risk Of Repurchase Agreement To Stockholders Equity	4.00%

Pledged Assets Repurchase Agree

Pledged Assets Repurchase Agreements with Counterparties Greater than or Equal to 5% of Equity at Risk (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018USD ($)days	Dec. 31, 2017USD ($)days
Repurchase Agreements with Counterparties Greater than or equal to 5% of Equity at Risk [Line Items]
Document Period End Date	Dec. 31, 2018
Securities Sold under Agreements to Repurchase | $	$ 75,717	$ 50,296
Risk Of Repurchase Agreement To Stockholders Equity	4.00%
Weighted Average Days to Maturity | days	49	116
FICC [Member]
Repurchase Agreements with Counterparties Greater than or equal to 5% of Equity at Risk [Line Items]
Risk Of Repurchase Agreement To Stockholders Equity	8.00%

Pledged Assets (Assets Pledged

Pledged Assets (Assets Pledged as Collateral) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Offsetting Assets and Liabilities [Line Items]
Pledged Financial Instruments, Not Separately Reported, Mortgage-Related Securities Available-for-sale or Held-for-investment	$ 79,182	$ 52,497
Document Period End Date	Dec. 31, 2018
Retained Interests in Consolidated VIE's Pledged as Collateral Under Repurchase Agreements	$ 163	182
Accrued interest on pledged securities	248	158
Restricted cash and cash equivalents	599	317
Total Fair Value of Securities Pledged and Accrued Interest	81,210
Total Fair Value Of Agency Securities Pledged And Accrued Interest		54,559
Repurchase Agreements [Member]
Offsetting Assets and Liabilities [Line Items]
Pledged Financial Instruments, Not Separately Reported, Mortgage-Related Securities Available-for-sale or Held-for-investment	78,997	52,497
Derivative [Member]
Offsetting Assets and Liabilities [Line Items]
Pledged Financial Instruments, Not Separately Reported, Mortgage-Related Securities Available-for-sale or Held-for-investment	174	221
Accrued interest on pledged securities		1
Restricted cash and cash equivalents	522	281
Total Fair Value of Securities Pledged and Accrued Interest	697
Total Fair Value Of Agency Securities Pledged And Accrued Interest		575
Repurchase Agreements [Member]
Offsetting Assets and Liabilities [Line Items]
Accrued interest on pledged securities	246	153
Total Fair Value of Securities Pledged and Accrued Interest	79,943
Total Fair Value Of Agency Securities Pledged And Accrued Interest		52,798
Variable Interest Entity, Primary Beneficiary [Member]
Offsetting Assets and Liabilities [Line Items]
Pledged Financial Instruments, Not Separately Reported, Mortgage-Related Securities Available-for-sale or Held-for-investment	436	662
Accrued interest on pledged securities	1	2
Total Fair Value of Securities Pledged and Accrued Interest	437
Total Fair Value Of Agency Securities Pledged And Accrued Interest		664
Under Prime Broker Agreements [Member]
Offsetting Assets and Liabilities [Line Items]
Pledged Financial Instruments, Not Separately Reported, Mortgage-Related Securities Available-for-sale or Held-for-investment	133	519
Accrued interest on pledged securities	0	2
Total Fair Value of Securities Pledged and Accrued Interest	133
Total Fair Value Of Agency Securities Pledged And Accrued Interest		522
Includes Sold But Not Yet Settled Securities [Member]
Offsetting Assets and Liabilities [Line Items]
Pledged Financial Instruments, Not Separately Reported, Mortgage-Related Securities Available-for-sale or Held-for-investment	79,740	53,899
Credit Risk Transfer Securities [Member]
Offsetting Assets and Liabilities [Line Items]
Pledged Financial Instruments, Not Separately Reported, Mortgage-Related Securities Available-for-sale or Held-for-investment	141	0
Credit Risk Transfer Securities [Member] | Repurchase Agreements [Member]
Offsetting Assets and Liabilities [Line Items]
Pledged Financial Instruments, Not Separately Reported, Mortgage-Related Securities Available-for-sale or Held-for-investment	141
Credit Risk Transfer Securities [Member] | Derivative [Member]
Offsetting Assets and Liabilities [Line Items]
Pledged Financial Instruments, Not Separately Reported, Mortgage-Related Securities Available-for-sale or Held-for-investment	0
Non-Agency [Member]
Offsetting Assets and Liabilities [Line Items]
Pledged Financial Instruments, Not Separately Reported, Mortgage-Related Securities Available-for-sale or Held-for-investment	45
Non-Agency [Member] | Repurchase Agreements [Member]
Offsetting Assets and Liabilities [Line Items]
Pledged Financial Instruments, Not Separately Reported, Mortgage-Related Securities Available-for-sale or Held-for-investment	45
Non-Agency [Member] | Derivative [Member]
Offsetting Assets and Liabilities [Line Items]
Pledged Financial Instruments, Not Separately Reported, Mortgage-Related Securities Available-for-sale or Held-for-investment	0
US Treasury Securities [Member]
Offsetting Assets and Liabilities [Line Items]
Pledged Financial Instruments, Not Separately Reported, Mortgage-Related Securities Available-for-sale or Held-for-investment	437	185
US Treasury Securities [Member] | Repurchase Agreements [Member]
Offsetting Assets and Liabilities [Line Items]
Pledged Financial Instruments, Not Separately Reported, Mortgage-Related Securities Available-for-sale or Held-for-investment	437	113
US Treasury Securities [Member] | Derivative [Member]
Offsetting Assets and Liabilities [Line Items]
Pledged Financial Instruments, Not Separately Reported, Mortgage-Related Securities Available-for-sale or Held-for-investment	0	72
Derivative [Member]
Offsetting Assets and Liabilities [Line Items]
Accrued interest on pledged securities	1
Repurchase Agreements [Member]
Offsetting Assets and Liabilities [Line Items]
Restricted cash and cash equivalents	77	35
Under Prime Broker Agreements [Member]
Offsetting Assets and Liabilities [Line Items]
Restricted cash and cash equivalents	0	1
Excluding Cash Received [Member]
Offsetting Assets and Liabilities [Line Items]
Restricted cash and cash equivalents	$ 599	$ 317

Pledged Assets (Securities Pled

Pledged Assets (Securities Pledged as Collateral) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Offsetting Assets and Liabilities [Line Items]
Document Period End Date	Dec. 31, 2018
Retained Interests in Consolidated VIE's Pledged as Collateral Under Repo	$ 163	$ 182
Security Owned and Pledged as Collateral, Fair Value	79,182	52,497
Agency Securities Pledged As Collateral Amortized Cost	80,386	52,899
Agency Securities Pledged As Collateral Accrued Interest	247	153
Maturity Less than 30 Days [Member]
Offsetting Assets and Liabilities [Line Items]
Security Owned and Pledged as Collateral, Fair Value	49,944	20,162
Agency Securities Pledged As Collateral Amortized Cost	50,654	20,313
Agency Securities Pledged As Collateral Accrued Interest	156	59
Maturity 31 To 59 Days [Member]
Offsetting Assets and Liabilities [Line Items]
Security Owned and Pledged as Collateral, Fair Value	14,586	12,950
Agency Securities Pledged As Collateral Amortized Cost	14,810	13,061
Agency Securities Pledged As Collateral Accrued Interest	46	38
Maturity 60 To 90 Days [Member]
Offsetting Assets and Liabilities [Line Items]
Security Owned and Pledged as Collateral, Fair Value	7,770	4,000
Agency Securities Pledged As Collateral Amortized Cost	7,843	4,013
Agency Securities Pledged As Collateral Accrued Interest	24	11
Maturity over 90 days [Member]
Offsetting Assets and Liabilities [Line Items]
Security Owned and Pledged as Collateral, Fair Value	6,882	15,385
Agency Securities Pledged As Collateral Amortized Cost	7,079	15,512
Agency Securities Pledged As Collateral Accrued Interest	21	45
US Treasury Securities [Member]
Offsetting Assets and Liabilities [Line Items]
Security Owned and Pledged as Collateral, Fair Value	437	$ 185
Securities Received as Collateral, Amount Repledged and Sold	$ 437

Pledged Assets (Assets Pledge_2

Pledged Assets (Assets Pledged from Counterparties) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Offsetting Assets and Liabilities [Line Items]
Document Period End Date	Dec. 31, 2018
Obligation to Return Securities Borrowed Under Reverse Repurchase Agreements at Fair Value	$ 21,431	$ 10,467
Restricted Cash and Cash Equivalents	599	317
Assets Pledged to Us [Member]
Offsetting Assets and Liabilities [Line Items]
Restricted Cash and Cash Equivalents	129	82
Restricted Cash and Securities Pledged	22,077	10,935
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] | Assets Pledged to Us [Member]
Offsetting Assets and Liabilities [Line Items]
Pledged Financial Instruments, Not Separately Reported, Mortgage-Related Securities Available-for-sale or Held-for-investment	37	0
Securities Sold under Agreements to Repurchase [Member] | Assets Pledged to Us [Member]
Offsetting Assets and Liabilities [Line Items]
Pledged Financial Instruments, Not Separately Reported, Mortgage-Related Securities Available-for-sale or Held-for-investment	37	0
Derivative [Member] | Assets Pledged to Us [Member]
Offsetting Assets and Liabilities [Line Items]
Restricted Cash and Securities Pledged	164	82
US Treasury Securities [Member] | Assets Pledged to Us [Member]
Offsetting Assets and Liabilities [Line Items]
Pledged Financial Instruments, Not Separately Reported, Mortgage-Related Securities Available-for-sale or Held-for-investment	21,948	10,853
Reverse Repurchase Agreements [Member] | Assets Pledged to Us [Member]
Offsetting Assets and Liabilities [Line Items]
Pledged Financial Instruments, Not Separately Reported, Mortgage-Related Securities Available-for-sale or Held-for-investment	21,876	10,853
Reverse Repurchase Agreements [Member] | US Treasury Securities [Member] | Assets Pledged to Us [Member]
Offsetting Assets and Liabilities [Line Items]
Pledged Financial Instruments, Not Separately Reported, Mortgage-Related Securities Available-for-sale or Held-for-investment	21,876	10,853
Derivative [Member]
Offsetting Assets and Liabilities [Line Items]
Restricted Cash and Cash Equivalents	522	281
Derivative [Member] | US Treasury Securities [Member] | Assets Pledged to Us [Member]
Offsetting Assets and Liabilities [Line Items]
Pledged Financial Instruments, Not Separately Reported, Mortgage-Related Securities Available-for-sale or Held-for-investment	35	0
Derivative [Member] | Assets Pledged to Us [Member]
Offsetting Assets and Liabilities [Line Items]
Restricted Cash and Cash Equivalents	$ 129	$ 82

Pledged Assets (Offsetting Asse

Pledged Assets (Offsetting Assets and Liabilities) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Offsetting Assets and Liabilities [Line Items]
Document Period End Date	Dec. 31, 2018
Collateral Received	$ (4,733)
Assets [Member]
Offsetting Assets and Liabilities [Line Items]
Gross Amounts of Recognized Assets	22,086	$ 11,147
Gross Amount Offset in the Consolidated Balance Sheets	0
Net Amounts of Assets Presented in the Consolidated Balance Sheets	22,086	11,147
Financial Instruments	(17,276)	(9,705)
Collateral Received		(1,361)
Net Amount	77	81
Assets [Member] | ERROR in label resolution.
Offsetting Assets and Liabilities [Line Items]
Gross Amounts of Recognized Assets	163	156
Net Amounts of Assets Presented in the Consolidated Balance Sheets	163	156
Financial Instruments	0	(1)
Collateral Received	(158)	(82)
Net Amount	5	73
Assets [Member] | TBA and Forward Settling Agency Securities [Member]
Offsetting Assets and Liabilities [Line Items]
Gross Amounts of Recognized Assets	110	30
Net Amounts of Assets Presented in the Consolidated Balance Sheets	110	30
Financial Instruments	(40)	(22)
Net Amount	70	8
Assets [Member] | Reverse Repurchase Agreements [Member]
Offsetting Assets and Liabilities [Line Items]
Net Amount	2
Liability [Member]
Offsetting Assets and Liabilities [Line Items]
Gross Amounts of Recognized Assets	75,757	50,324
Gross Amount Offset in the Consolidated Balance Sheets	0
Net Amounts of Assets Presented in the Consolidated Balance Sheets	75,757	50,324
Financial Instruments	(17,276)	(9,705)
Collateral Received	(58,481)	(40,619)
Net Amount	0
Liability [Member] | Repurchase Agreements [Member]
Offsetting Assets and Liabilities [Line Items]
Net Amount	0	0
Liability [Member] | ERROR in label resolution.
Offsetting Assets and Liabilities [Line Items]
Gross Amounts of Recognized Assets	0	1
Net Amounts of Assets Presented in the Consolidated Balance Sheets	0	1
Financial Instruments	0	(1)
Collateral Received	0	0
Net Amount	0	0
Liability [Member] | TBA and Forward Settling Agency Securities [Member]
Offsetting Assets and Liabilities [Line Items]
Gross Amounts of Recognized Assets	40	27
Net Amounts of Assets Presented in the Consolidated Balance Sheets	40	27
Financial Instruments	(40)	(22)
Collateral Received	0	(5)
Net Amount	0	0
Reverse Repurchase Agreements [Member] | Assets [Member]
Offsetting Assets and Liabilities [Line Items]
Gross Amounts of Recognized Assets	21,813	10,961
Gross Amount Offset in the Consolidated Balance Sheets	0
Net Amounts of Assets Presented in the Consolidated Balance Sheets	21,813	10,961
Financial Instruments	(17,236)	(9,682)
Collateral Received	(4,575)	(1,279)
Repurchase Agreements [Member] | Liability [Member]
Offsetting Assets and Liabilities [Line Items]
Gross Amounts of Recognized Assets	75,717	50,296
Gross Amount Offset in the Consolidated Balance Sheets	0
Net Amounts of Assets Presented in the Consolidated Balance Sheets	75,717	50,296
Financial Instruments	(17,236)	(9,682)
Collateral Received	$ (58,481)	$ (40,614)

Fair Value Measurements (Detail

Fair Value Measurements (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Future [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | US Treasury Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
TBA securities	$ 0	$ 19
Derivative Liability	(44)	0
Interest Rate Swaption [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate swaps	37	75
Interest Rate Swap [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate swaps	126	81
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]
Interest rate swaps	0	1
Purchases Of TBAs And Forward Settling Agency Securities [Member] | 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]
TBA securities	$ 110	30
Document Period End Date	Dec. 31, 2018
Transfers between hierarchy levels	0
Agency securities	$ 82,291	55,506
Agency securities transferred to consolidated VIEs	436	662
Non-Agency Securities, at Fair Value	548	36
Financial Instruments, Owned, Other, at Fair Value	1,012	876
U.S. Treasury securities	46	0
Equity Securities, FV-NI	0	29
TBA securities	273	205
Derivative Liability	84	28
Debt of consolidated variable interest entities, at fair value	275	357
Obligation to return securities borrowed under reverse repurchase agreements, at fair value	21,431	10,467
Interest rate swaps	273	205
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	46	48
Total liabilities	21,387	10,467
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	84,560	57,266
Total liabilities	315	385
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 Liability	$ 40	$ 27

Net Income (Loss) Per Common _2

Net Income (Loss) Per Common Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Weighted Average Number of Shares Outstanding, Basic	504.2	462.3	404.9	391.3	391.3	364.7	346.4	331	441.1	358.6	331.9
Dilutive Securities, Effect on Basic Earnings Per Share, Options and Restrictive Stock Units									$ 0.3	$ 0.1	$ 0
Weighted Average Number of Shares Outstanding, Diluted	504.2	462.7	405.2	391.5	391.5	364.9	346.5	331.1	441.4	358.7	331.9
Net Income (Loss) Available to Common Stockholders, Basic	$ (813)	$ 207	$ 284	$ 415	$ 376	$ 271	$ 17	$ 69	$ 93	$ 733	$ 595
Earnings Per Share, Basic	$ (1.61)	$ 0.45	$ 0.70	$ 1.06	$ 0.96	$ 0.74	$ 0.05	$ 0.21	$ 0.21	$ 2.04	$ 1.79
Earnings Per Share, Diluted									$ 0.21	$ 2.04	$ 1.79

Stockholders' Equity (Preferred

Stockholders' Equity (Preferred Stock) (Details) - USD ($) $ / shares in Units, $ in Millions	Aug. 16, 2017	May 31, 2014	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2012	Sep. 12, 2017	May 05, 2014	Apr. 30, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Document Period End Date			Dec. 31, 2018
Preferred Stock Authorized, but not Issued			10,000,000
Preferred Stock, Shares Authorized			10,000,000
Series A Preferred Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Preferred Stock, Dividend Rate, Percentage					8.00%
Preferred Stock, Liquidation Preference Per Share								$ 25
Payments for Repurchase of Redeemable Preferred Stock	$ 173
Series B Preferred Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Preferred Stock, Percent Interest Per Share		0.10%
Preferred Stock, Capital Shares Reserved for Future Issuance			8,050
Preferred Stock, Dividend Rate, Percentage				7.75%
Preferred Stock, Liquidation Preference Per Share							$ 25
Preferred Stock, Shares Issued			7,000
Series C Preferred Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Preferred Stock, Capital Shares Reserved for Future Issuance			13,800
Preferred Stock, Dividend Rate, Percentage			5.111%	7.00%
Preferred Stock, Liquidation Preference Per Share						$ 25
Preferred Stock, Shares Issued			13,000
Depositary Share [Member] | Series B Preferred Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Preferred Stock, Shares Issued							7,000,000
Depositary Share [Member] | Series C Preferred Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Preferred Stock, Shares Issued						13,000,000

Stockholders' Equity (Common St

Stockholders' Equity (Common Stock Repurchase Program) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Repurchase of common stock shares			(6.5)
Average repurchase price (in dollars per share)			$ 17.89
Repurchase of common stock, value			$ 116
Payments for Repurchase of Common Stock	$ 0	$ 0	$ 116
Common Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Repurchase of common stock shares			(6.5)
Repurchase of common stock, value			$ 0

Stockholders' Equity (Accumulat

Stockholders' Equity (Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Other Comprehensive Income (Loss), Securities, Available-for-Sale, Unrealized Holding Gain (Loss) Arising During Period, after Tax	$ 361	$ (193)	$ (145)	$ (621)	$ (205)	$ 90	$ 121	$ 46	$ (598)	$ 52	$ (370)
Amounts reclassified from accumulated OCI									0	0	39
Agency Securities [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Beginning OCI Balance				$ (345)				$ (397)	(345)	(397)	(66)
Other Comprehensive Income (Loss), Securities, Available-for-Sale, Unrealized Holding Gain (Loss) Arising During Period, after Tax									(677)	(31)	(261)
Amounts reclassified from accumulated OCI									79	83	(109)
Ending OCI Balance	$ (943)				$ (345)				$ (943)	$ (345)	$ (397)

Stockholders' Equity (Follow-On

Stockholders' Equity (Follow-On Equity Offerings) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	Nov. 19, 2018	Aug. 03, 2018	May 29, 2018	Sep. 12, 2017	May 05, 2017	Dec. 31, 2018	Dec. 31, 2017
Class of Stock [Line Items]
Sale of Stock, Price Per Share	$ 17.09	$ 18.68	$ 18.35	$ 20.47	$ 20.51	$ 18.03	$ 20.96
Stock Issued During Period, Shares, New Issues	46	43.7	34.5	28.2	24.5
Stock Issued During Period, Value, New Issues	$ 786	$ 817	$ 633	$ 577	$ 503	$ 2,611	$ 1,238
Follow-On Public Offering [Member]
Class of Stock [Line Items]
Stock Issued During Period, Shares, New Issues						124.2	52.7
Stock Issued During Period, Value, New Issues						$ 2,236	$ 1,080

Stockholders' Equity (At-the-Ma

Stockholders' Equity (At-the-Market Offering Program) (Details) - USD ($) $ / shares in Units, $ in Millions	Nov. 19, 2018	Aug. 03, 2018	May 29, 2018	Sep. 12, 2017	May 05, 2017	Dec. 31, 2018	Dec. 31, 2017	Jun. 14, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, Value of Shares Approved for Future Issuance								$ 1,000
Common Stock, Shares Authorized						$ 660
Stock Issued During Period, Shares, New Issues	46,000,000	43,700,000	34,500,000	28,200,000	24,500,000
Stock Issued During Period, Value, New Issues	$ 786	$ 817	$ 633	$ 577	$ 503	$ 2,611	$ 1,238
Sale of Stock, Price Per Share	$ 17.09	$ 18.68	$ 18.35	$ 20.47	$ 20.51	$ 18.03	$ 20.96
Common Stock At The Market Sale Agreement [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock Issued During Period, Shares, New Issues						20,773,191	7,570,296
Stock Issued During Period, Value, New Issues						$ 375.4	$ 158.7

Stockholders' Equity (Dividend

Stockholders' Equity (Dividend Reinvestment and Direct Stock Purchase Plan) (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Dividends, Preferred Stock		$ 9	$ 14
Preferred Stock, Dividend Rate, Per-Dollar-Amount		$ 1.333	$ 2
Dividends, Common Stock	$ 964	$ 777	$ 763
Common Stock, Dividends, Per Share, Cash Paid	$ 2.16	$ 2.16	$ 2.3
Preferred Class B [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Dividends, Preferred Stock	$ 14	$ 14	$ 14
Preferred Stock, Dividend Rate, Per-Dollar-Amount	$ 1.9375	$ 1.9375	$ 1.9375
Series C Preferred Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Dividends, Preferred Stock	$ 23	$ 9
Preferred Stock, Dividend Rate, Per-Dollar-Amount	$ 1.75	$ 0.69514

Stockholders' Equity Schedule o

Stockholders' Equity Schedule of Dividends Declared (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Dividends, Preferred Stock		$ 9	$ 14
Preferred Stock, Dividend Rate, Per-Dollar-Amount		$ 1.333	$ 2
Dividends, Common Stock	$ 964	$ 777	$ 763
Common Stock, Dividends, Per Share, Cash Paid	$ 2.16	$ 2.16	$ 2.3
Preferred Class B [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Dividends, Preferred Stock	$ 14	$ 14	$ 14
Preferred Stock, Dividend Rate, Per-Dollar-Amount	$ 1.9375	$ 1.9375	$ 1.9375
Series C Preferred Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Dividends, Preferred Stock	$ 23	$ 9
Preferred Stock, Dividend Rate, Per-Dollar-Amount	$ 1.75	$ 0.69514

Equity Incentive Plan Narrative

Equity Incentive Plan Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number		0	0	5,000
Document Period End Date	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value		$ 0	$ 17.49	$ 21.44
Accrued RSU Dividend Equivalents		1,032	3,527
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period			(5,000)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value		$ 16.69	$ 20
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Vest Date Fair Value		$ 20.15	$ 18.99
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized	$ 10,918,000
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition	1 year 7 months 28 days
2016 Equity Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized	10,000,000
Restricted Stock or Unit Expense	$ 185,285
Deferred Compensation Share-based Arrangements, Liability, Current and Noncurrent	300,000
Allocated Share-based Compensation Expense	$ 6,060,000	$ 3,066,000	$ 28,000
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant	7,941,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value	$ 16.08	$ 17.46	$ 17.72
Accrued RSU Dividend Equivalents	56,618	32,498	968
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value	$ 16.52	$ 16.08
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Vest Date Fair Value	$ 18.60	$ 20.42
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period	(546)	(246)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value	$ 16.98	$ 18.29
Director Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense	$ 528,000	$ 455,000	$ 731,000
MTGE Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense	$ 4,859,000	$ 782,224
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number		0	21,435	31,431
Restricted Stock or Unit Expense			$ 625,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period			33,015
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value			$ 18.93
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period		(22,467)	(46,538)
Restricted Stock Units (RSUs) [Member] | 2016 Equity Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number	501,913	335,228	102,375
Restricted Stock or Unit Expense	$ 4,213,000	$ 4,150,000	$ 1,814,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	261,036	238,203	101,407
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 18.05	$ 19.52	$ 17.89
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period	(150,423)	(37,602)
Restricted Stock Units (RSUs) [Member] | MTGE Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted Stock or Unit Expense	$ 2,344,437	$ 2,344,437
Performance Shares [Member] | 2016 Equity Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value	$ 16.08	$ 17.78
Accrued RSU Dividend Equivalents	61,171	22,767
Performance Shares [Member] | Restricted Stock Units (RSUs) [Member] | 2016 Equity Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number	606,775	273,376
Restricted Stock or Unit Expense	$ 4,895,000	$ 4,859,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	272,228	250,609
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 17.98	$ 19.39
Director [Member] | Restricted Stock Units (RSUs) [Member] | 2016 Equity Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted Stock or Unit Expense	$ 500,000	$ 500,000
Share Distribution [Member] | Restricted Stock Units (RSUs) [Member] | MTGE Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted Stock or Unit Expense	$ 3,540,711

Income Taxes (Details)

Income Taxes (Details)	12 Months Ended
	Dec. 31, 2018
Investments, Owned, Federal Income Tax Note [Line Items]
Required Annual Distribution of Taxable Net Income	90.00%

Management Agreement and Rela_2

Management Agreement and Related Party Transactions (Details) - USD ($) $ in Millions	May 02, 2018	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Related Party Transactions [Abstract]
Gain (Loss) on Contract Termination	$ 42
Management fees										$ 0	$ 0	$ 52
Monthly Management Fee Income										12	16	8
Labor and Related Expense		$ 11	$ 14	$ 10	$ 10	$ 12	$ 10	$ 10	$ 10	45	$ 42	$ 19
Indefinite-lived Intangible Assets, Written off Related to Sale of Business Unit										$ 23

Quarterly Results (Details)

Quarterly Results (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Interest income	$ 604	$ 500	$ 414	$ 431	$ 386	$ 318	$ 293	$ 296	$ 1,949	$ 1,293	$ 1,321
Interest expense	418	312	237	206	174	140	112	98	1,173	524	394
Net interest income	186	188	177	225	212	178	181	198	776	769	927
Noninterest Income [Abstract]
Gain (loss) on sale of investment securities, net	(21)	(40)	(74)	(2)	(16)	22	15	(84)	(137)	(63)	109
Unrealized loss on investment securities measured at fair value through net income, net	683	(363)	(94)	(523)	(65)	(31)	9	16	(297)	(71)	(6)
(Loss) gain on derivative instruments and other securities, net	(1,633)	430	298	738	271	131	(169)	(40)	(167)	193	(310)
Management Fee Income	$ 0	$ 46	$ 4	$ 4	$ 4	$ 4	$ 4	$ 4	$ 54	$ 16	$ 8
Weighted Average Number of Shares Outstanding, Diluted	504.2	462.7	405.2	391.5	391.5	364.9	346.5	331.1	441.4	358.7	331.9
Earnings Per Share, Basic	$ (1.61)	$ 0.45	$ 0.70	$ 1.06	$ 0.96	$ 0.74	$ 0.05	$ 0.21	$ 0.21	$ 2.04	$ 1.79
Total other (loss) income, net	$ (971)	$ 73	$ 134	$ 217	$ 194	$ 126	$ (141)	$ (104)	$ (547)	$ 75	$ (199)
Management fees									0	0	52
Labor and Related Expense	11	14	10	10	12	10	10	10	45	42	19
General and administrative expenses	8	31	8	8	9	8	6	8	55	31	34
Total expenses	19	45	18	18	21	18	16	18	100	73	105
Net income (loss)	(804)	216	293	424	385	286	24	76	129	771	623
Dividend on preferred stock	9	9	9	9	9	9	7	7	36	32	28
Net income (loss) available (attributable) to common shareholders	(813)	207	284	415	376	271	17	69	93	733	595
Unrealized Gains and (Losses), Net	$ 361	$ (193)	$ (145)	$ (621)	(205)	90	121	46	(598)	52	(370)
Issuance costs of redeemed preferred stock					$ 0	$ 6	$ 0	$ 0	$ 0	$ 6	$ 0
Weighted Average Number of Shares Outstanding, Basic	504.2	462.3	404.9	391.3	391.3	364.7	346.4	331	441.1	358.6	331.9
Unrealized gain on derivative instruments, net									$ 0	$ 0	$ 39
Other comprehensive (loss) income									(598)	52	(331)
Comprehensive (loss) income	$ (443)	$ 23	$ 148	$ (197)	$ 180	$ 376	$ 145	$ 122	(469)	823	292
Comprehensive (loss) income (attributable) available to common shareholders	$ (452)	$ 14	$ 139	$ (206)	$ 171	$ 361	$ 138	$ 115	$ (505)	$ 785	$ 264
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Common Stock, Dividends, Per Share, Declared	$ 0.54	$ 0.54	$ 0.54	$ 0.54	$ 0.54	$ 0.54	$ 0.54	$ 0.54
Comprehensive income per share - basic and diluted	$ (0.90)	$ 0.03	$ 0.34	$ (0.53)	$ 0.44	$ 0.99	$ 0.40	$ 0.35

Subsequent Event (Details)

Subsequent Event (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	Feb. 12, 2019	Nov. 19, 2018	Aug. 03, 2018	May 29, 2018	May 02, 2018	Sep. 12, 2017	May 05, 2017	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Subsequent Event [Line Items]
Common Stock, Dividends, Per Share, Declared								$ 0.54	$ 0.54	$ 0.54	$ 0.54	$ 0.54	$ 0.54	$ 0.54	$ 0.54
Stock Issued During Period, Shares, New Issues		46	43.7	34.5		28.2	24.5
Stock Issued During Period, Value, New Issues		$ 786	$ 817	$ 633		$ 577	$ 503									$ 2,611	$ 1,238
Gain (Loss) on Contract Termination					$ 42
Sale of Stock, Price Per Share		$ 17.09	$ 18.68	$ 18.35		$ 20.47	$ 20.51	$ 18.03				$ 20.96				$ 18.03	$ 20.96
Subsequent Event [Member]
Subsequent Event [Line Items]
Common Stock, Dividends, Per Share, Declared	$ 0.18
Common Stock [Member]
Subsequent Event [Line Items]
Stock Issued During Period, Shares, New Issues																145	60.3
Stock Issued During Period, Value, New Issues																$ 1	$ 1

Uncategorized Items - agnc-2018

Label	Element	Value
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	$ 2,391,000,000