Federal National Mortgage Association (FNMA) 10-Q 2 Aug 18 2018 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information	6 Months Ended
	Jun. 30, 2018shares
Entity [Abstract]
Entity Registrant Name	FEDERAL NATIONAL MORTGAGE ASSOCIATION FANNIE MAE
Entity Central Index Key	310,522
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	Jun. 30, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q2
Amendment Flag	false
Entity Common Stock, Shares Outstanding	1,158,087,567

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Assets:
Cash and cash equivalents	$ 20,853	$ 32,110
Restricted cash (includes $22,774 and $22,132, respectively, related to consolidated trusts)	27,876	28,150
Federal funds sold and securities purchased under agreements to resell or similar arrangements	16,300	19,470
Investments in securities:
Trading, at fair value (includes $3,363 and $747, respectively, pledged as collateral)	42,381	34,679
Available-for-sale, at fair value	3,723	4,843
Total investments in securities	46,104	39,522
Mortgage loans:
Loans held for sale, at lower of cost or fair value	14,323	4,988
Loans held for investment, at amortized cost	3,211,113	3,192,621
Allowance for loan losses	(16,812)	(19,084)
Total loans held for investment, net of allowance	3,194,301	3,173,537
Total mortgage loans	3,208,624	3,178,525
Deferred tax assets, net	15,375	17,350
Accrued interest receivable, net (includes $7,702 and $7,560, respectively, related to consolidated trusts)	8,256	8,133
Acquired property, net	2,816	3,220
Other assets	17,160	19,049
Total assets	3,363,364	3,345,529
Liabilities:
Accrued interest payable (includes $8,751 and $8,598, respectively, related to consolidated trusts)	9,825	9,682
Other liabilities (includes $353 and $492, respectively, related to consolidated trusts)	8,591	9,479
Total liabilities	3,355,905	3,349,215
Commitments and contingencies (Note 14)	0	0
Fannie Mae stockholders’ equity (deficit):
Senior preferred stock, 1,000,000 shares issued and outstanding	120,836	117,149
Preferred stock, 700,000,000 shares are authorized—555,374,922 shares issued and outstanding	19,130	19,130
Common stock, no par value, no maximum authorization—1,308,762,703 shares issued and 1,158,087,567 shares outstanding	687	687
Accumulated deficit	(126,143)	(133,805)
Accumulated other comprehensive income	349	553
Treasury stock, at cost, 150,675,136 shares	(7,400)	(7,400)
Total stockholders’ equity (deficit) (See Note 1: Senior Preferred Stock Purchase Agreement and Senior Preferred Stock for information on our dividend obligation to Treasury)	7,459	(3,686)
Total liabilities and equity (deficit)	3,363,364	3,345,529
Fannie Mae [Member]
Mortgage loans:
Loans held for investment, at amortized cost	140,154	162,809
Liabilities:
Debt (includes $7,558 and $8,186, respectively, of debt of Fannie Mae at fair value and $26,675 and $30,493, respectively, of debt of consolidated trusts, at fair value)	250,690	276,752
Consolidated Trusts [Member]
Assets:
Restricted cash (includes $22,774 and $22,132, respectively, related to consolidated trusts)	22,774	22,132
Mortgage loans:
Loans held for investment, at amortized cost	3,070,959	3,029,812
Accrued interest receivable, net (includes $7,702 and $7,560, respectively, related to consolidated trusts)	7,702	7,560
Liabilities:
Accrued interest payable (includes $8,751 and $8,598, respectively, related to consolidated trusts)	8,751	8,598
Debt (includes $7,558 and $8,186, respectively, of debt of Fannie Mae at fair value and $26,675 and $30,493, respectively, of debt of consolidated trusts, at fair value)	3,086,799	3,053,302
Other liabilities (includes $353 and $492, respectively, related to consolidated trusts)	$ 353	$ 492

Condensed Consolidated Balance3

Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Assets:
Restricted cash (includes $22,774 and $22,132, respectively, related to consolidated trusts)	$ 27,876	$ 28,150
Investments in securities:
Trading, at fair value (includes $3,363 and $747, respectively, pledged as collateral)	3,363	747
Available-for-sale, at fair value	3,723	4,843
Accrued interest receivable, net (includes $7,702 and $7,560, respectively, related to consolidated trusts)	8,256	8,133
Mortgage loans:
Total loans held for investment (includes $9,628 and $10,596, respectively, at fair value)	9,628	10,596
Liabilities:
Accrued interest payable (includes $8,751 and $8,598, respectively, related to consolidated trusts)	9,825	9,682
Other liabilities (includes $353 and $492, respectively, related to consolidated trusts)	$ 8,591	$ 9,479
Fannie Mae stockholders’ equity (deficit):
Senior preferred stock, 1,000,000 shares issued	1,000,000	1,000,000
Senior preferred stock, 1,000,000 shares outstanding	1,000,000	1,000,000
Preferred stock, 700,000,000 shares are authorized	700,000,000	700,000,000
Preferred stock, 555,374,922 shares issued	555,374,922	555,374,922
Preferred stock, 555,374,922 shares outstanding	555,374,922	555,374,922
Common stock, 1,308,762,703 shares issued	1,308,762,703	1,308,762,703
Common stock, 1,158,087,567 shares outstanding	1,158,087,567	1,158,087,567
Treasury stock, at cost, 150,675,136 shares	150,675,136	150,675,136
Consolidated Trusts [Member]
Assets:
Restricted cash (includes $22,774 and $22,132, respectively, related to consolidated trusts)	$ 22,774	$ 22,132
Investments in securities:
Accrued interest receivable, net (includes $7,702 and $7,560, respectively, related to consolidated trusts)	7,702	7,560
Liabilities:
Accrued interest payable (includes $8,751 and $8,598, respectively, related to consolidated trusts)	8,751	8,598
Debt (includes $8,491 and $9,582, respectively, of debt of Fannie Mae at fair value and $32,760 and $36,524, respectively, of debt of consolidated trusts, at fair value)	26,675	30,493
Other liabilities (includes $353 and $492, respectively, related to consolidated trusts)	353	492
Fannie Mae [Member]
Liabilities:
Debt (includes $8,491 and $9,582, respectively, of debt of Fannie Mae at fair value and $32,760 and $36,524, respectively, of debt of consolidated trusts, at fair value)	$ 7,558	$ 8,186

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations and Comprehensive Income (Unaudited) - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Interest income:
Trading securities	$ 318	$ 176	$ 554	$ 318
Available-for-sale securities	50	91	121	192
Mortgage loans (includes $26,521 and $25,033, respectively, for the three months ended and $52,819 and $49,987, respectively, for the six months ended related to consolidated trusts)	28,307	27,011	56,341	54,058
Other	182	115	355	209
Total interest income	28,857	27,393	57,371	54,777
Interest expense:
Short-term debt	(110)	(57)	(217)	(101)
Long-term debt (includes $21,896 and $20,705, respectively, for the three months ended and $43,611 and $41,013, respectively, for the six months ended related to consolidated trusts)	(23,370)	(22,334)	(46,545)	(44,328)
Total interest expense	(23,480)	(22,391)	(46,762)	(44,429)
Net interest income	5,377	5,002	10,609	10,348
Benefit for credit losses	1,296	1,267	1,513	1,663
Net interest income after benefit for credit losses	6,673	6,269	12,122	12,011
Non-interest income (loss):
Investment gains, net	277	385	527	376
Fair value gains (losses), net	229	(691)	1,274	(731)
Fee and other income	239	353	559	602
Non-interest income	745	47	2,360	247
Administrative expenses:
Salaries and employee benefits	(365)	(332)	(746)	(676)
Professional services	(254)	(234)	(497)	(463)
Other administrative expenses	(136)	(120)	(262)	(231)
Total administrative expenses	(755)	(686)	(1,505)	(1,370)
Foreclosed property expense	(139)	(34)	(301)	(251)
Temporary Payroll Tax Cut Continuation Act of 2011 (“TCCA”) fees	(565)	(518)	(1,122)	(1,021)
Other expenses, net	(366)	(291)	(569)	(673)
Total expenses	(1,825)	(1,529)	(3,497)	(3,315)
Income before federal income taxes	5,593	4,787	10,985	8,943
Provision for federal income taxes	(1,136)	(1,587)	(2,267)	(2,970)
Net income	4,457	3,200	8,718	5,973
Other comprehensive income (loss):
Changes in unrealized gains on available-for-sale securities, net of reclassification adjustments and taxes	4	(81)	(316)	(73)
Other	(2)	(2)	(5)	(4)
Total other comprehensive income (loss)	2	(83)	(321)	(77)
Total comprehensive income	4,459	3,117	8,397	5,896
Net income	4,457	3,200	8,718	5,973
Dividends distributed or available for distribution to senior preferred stockholder	(4,459)	(3,117)	(5,397)	(5,896)
Net income (loss) attributable to common stockholders	$ (2)	$ 83	$ 3,321	$ 77
Earnings per share, Basic	$ 0	$ 0.01	$ 0.58	$ 0.01
Earnings per share, Diluted	$ 0	$ 0.01	$ 0.56	$ 0.01
Weighted-average common shares outstanding, Basic	5,762	5,762	5,762	5,762
Weighted-average common shares outstanding, Diluted	5,762	5,893	5,893	5,893

Condensed Consolidated Stateme5

Condensed Consolidated Statements of Operations and Comprehensive Income (Unaudited) (Parenthetical) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Mortgage loans (includes $26,521 and $25,033, respectively, for the three months ended and $52,819 and $49,987, respectively, for the six months ended related to consolidated trusts)	$ 28,307	$ 27,011	$ 56,341	$ 54,058
Long-term debt (includes $21,896 and $20,705, respectively, for the three months ended and $43,611 and $41,013, respectively, for the six months ended related to consolidated trusts)	23,370	22,334	46,545	44,328
Consolidated Trusts [Member]
Mortgage loans (includes $26,521 and $25,033, respectively, for the three months ended and $52,819 and $49,987, respectively, for the six months ended related to consolidated trusts)	26,521	25,033	52,819	49,987
Long-term debt (includes $21,896 and $20,705, respectively, for the three months ended and $43,611 and $41,013, respectively, for the six months ended related to consolidated trusts)	$ 21,896	$ 20,705	$ 43,611	$ 41,013

Condensed Consolidated Stateme6

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Net cash provided by (used in) operating activities
Net cash provided by (used in) operating activities	$ (1,675)	$ (3,626)
Cash flows provided by investing activities:
Proceeds from maturities and paydowns of trading securities held for investment	141	937
Proceeds from sales of trading securities held for investment	96	124
Proceeds from maturities and paydowns of available-for-sale securities	417	1,214
Proceeds from sales of available-for-sale securities	672	922
Purchases of loans held for investment	(86,615)	(90,180)
Advances to lenders	(55,151)	(57,533)
Proceeds from disposition of acquired property and preforeclosure sales	4,848	6,874
Net change in federal funds sold and securities purchased under agreements to resell or similar arrangements	3,170	1,195
Other, net	(495)	(208)
Net cash provided by investing activities	80,506	87,117
Cash flows used in financing activities:
Payments of cash dividends on senior preferred stock to Treasury	(938)	(8,250)
Proceeds from senior preferred stock purchase agreement with Treasury	3,687	0
Other, net	(20)	11
Net cash used in financing activities	(90,362)	(97,765)
Net decrease in cash, cash equivalents and restricted cash	(11,531)	(14,274)
Cash, cash equivalents and restricted cash at beginning of period	60,260	62,177
Cash, cash equivalents and restricted cash at end of period	48,729	47,903
Cash paid during the period for:
Interest	54,408	56,207
Income taxes	460	1,070
Fannie Mae [Member]
Cash flows provided by investing activities:
Proceeds from repayments of loans acquired as held for investment	7,945	12,835
Proceeds from sales of loans acquired as held for investment of Fannie Mae	2,555	2,361
Cash flows used in financing activities:
Proceeds from issuance of debt	473,373	489,301
Payments to redeem debt	(499,674)	(510,340)
Consolidated Trusts [Member]
Cash flows provided by investing activities:
Proceeds from repayments of loans acquired as held for investment	202,923	208,576
Cash flows used in financing activities:
Proceeds from issuance of debt	172,507	181,764
Payments to redeem debt	$ (239,297)	$ (250,251)

Summary of Significant Accounti

Summary of Significant Accounting Policies	6 Months Ended
	Jun. 30, 2018
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies We are a stockholder-owned corporation organized and existing under the Federal National Mortgage Association Charter Act (the “Charter Act” or our “charter”). We are a government-sponsored enterprise and we are subject to government oversight and regulation. Our regulators include the Federal Housing Finance Agency (“FHFA”), the U.S. Department of Housing and Urban Development (“HUD”), the U.S. Securities and Exchange Commission (“SEC”), and the U.S. Department of the Treasury (“Treasury”). The U.S. government does not guarantee our securities or other obligations. We have been under conservatorship, with FHFA acting as conservator, since September 6, 2008. See “Note 1, Summary of Significant Accounting Policies” in our annual report on Form 10-K for the year ended December 31, 2017 (“ 2017 Form 10-K”) for additional information on our conservatorship and the impact of U.S. government support of our business. The unaudited interim condensed consolidated financial statements as of and for the three and six months ended June 30, 2018 , and related notes, should be read in conjunction with our audited consolidated financial statements and related notes included in our 2017 Form 10-K. Basis of Presentation The accompanying unaudited interim condensed consolidated financial statements have been prepared in accordance with generally accepted accounting principles in the United States of America (“GAAP”) for interim financial information and with the SEC’s instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and note disclosures required by GAAP for complete consolidated financial statements. In the opinion of management, all adjustments of a normal recurring nature considered necessary for a fair presentation have been included. The accompanying condensed consolidated financial statements include our accounts as well as the accounts of other entities in which we have a controlling financial interest. All intercompany accounts and transactions have been eliminated. To conform to our current period presentation, we have reclassified certain amounts reported in our prior periods’ condensed consolidated financial statements. Results for the three and six months ended June 30, 2018 may not necessarily be indicative of the results for the year ending December 31, 2018 . Use of Estimates Preparing condensed consolidated financial statements in accordance with GAAP requires management to make estimates and assumptions that affect our reported amounts of assets and liabilities, and disclosure of contingent assets and liabilities as of the dates of our condensed consolidated financial statements, as well as our reported amounts of revenues and expenses during the reporting periods. Management has made significant estimates in a variety of areas including, but not limited to, valuation of certain financial instruments and allowance for loan losses. Actual results could be different from these estimates. Senior Preferred Stock Purchase Agreement and Senior Preferred Stock Treasury has made a commitment under a senior preferred stock purchase agreement to provide funding to us under certain circumstances if we have a net worth deficit. In the first quarter of 2018, we received $3.7 billion from Treasury to eliminate our net worth deficit as of December 31, 2017 . Pursuant to the senior preferred stock purchase agreement, we have received a total of $119.8 billion from Treasury as of June 30, 2018 , and the amount of remaining funding available to us under the agreement was $113.9 billion . Pursuant to the senior preferred stock purchase agreement, we issued shares of senior preferred stock to Treasury in 2008. Acting as successor to the rights, titles, powers and privileges of the Board, our conservator has declared and directed us to pay dividends to Treasury on the senior preferred stock on a quarterly basis for every dividend period for which dividends were payable since we entered into conservatorship in 2008. Effective January 1, 2018, the dividend provisions of the senior preferred stock provide for quarterly dividends consisting of the amount, if any, by which our net worth as of the end of the immediately preceding fiscal quarter exceeds a $3.0 billion capital reserve amount. We refer to this as a “net worth sweep” dividend. On June 30, 2018 , we paid Treasury a dividend of $938 million based on our net worth of $3.9 billion as of March 31, 2018 , less the applicable capital reserve amount of $3.0 billion . Because we had a net worth of $7.5 billion as of June 30, 2018 , we expect to pay Treasury a dividend of $4.5 billion for the third quarter of 2018 by September 30, 2018 . The liquidation preference of the senior preferred stock is subject to adjustment. The aggregate liquidation preference of the senior preferred stock was $123.8 billion as of June 30, 2018 . See “Note 11, Equity (Deficit)” in our 2017 Form 10-K for additional information about the senior preferred stock purchase agreement and the senior preferred stock. Regulatory Capital We submit capital reports to FHFA, which monitors our capital levels. The deficit of core capital over statutory minimum capital was $ 136.3 billion as of June 30, 2018 and $144.4 billion as of December 31, 2017 . Due to the terms of our senior preferred stock described above, we do not expect to eliminate our deficit of core capital over statutory minimum capital. Related Parties As a result of our issuance to Treasury of a warrant to purchase shares of Fannie Mae common stock equal to 79.9% of the total number of shares of Fannie Mae common stock, we and Treasury are deemed related parties. As of June 30, 2018 , Treasury held an investment in our senior preferred stock with an aggregate liquidation preference of $123.8 billion . FHFA’s control of Fannie Mae and Freddie Mac has caused Fannie Mae, FHFA and Freddie Mac to be deemed related parties. In 2013, Fannie Mae and Freddie Mac established Common Securitization Solutions, LLC (“CSS”), a jointly owned limited liability company to operate a common securitization platform; therefore, CSS is deemed a related party. Transactions with Treasury Our administrative expenses were reduced by $6 million and $11 million for the three months ended June 30, 2018 and 2017 , respectively, and $13 million and $23 million for the six months ended June 30, 2018 and 2017 , respectively, due to reimbursements from Treasury and Freddie Mac for expenses incurred as program administrator for Treasury’s Home Affordable Modification Program and other initiatives under Treasury’s Making Home Affordable Program. We made tax payments to the Internal Revenue Service (“IRS”), a bureau of Treasury, of $460 million during the three and six months ended June 30, 2018 . We made tax payments of $1.1 billion during the three and six months ended June 30, 2017 . In 2009, we entered into a memorandum of understanding with Treasury, FHFA and Freddie Mac pursuant to which we agreed to provide assistance to state and local housing finance agencies (“HFAs”) through certain programs, including a new issue bond (“NIB”) program. As of June 30, 2018 , under the NIB program, Fannie Mae and Freddie Mac had $4.7 billion outstanding of pass-through securities backed by single-family and multifamily housing bonds issued by HFAs, which is less than 35% of the total original principal under the program, the amount of losses that Treasury would bear. Accordingly, we do not have a potential risk of loss under the NIB program. The fee revenue and expense related to the TCCA are recorded in “Mortgage loans interest income” and “TCCA fees,” respectively, in our condensed consolidated statements of operations and comprehensive income. We recognized $565 million and $518 million in TCCA fees during the three months ended June 30, 2018 and 2017 , respectively, and $1.1 billion and $1.0 billion for the six months ended June 30, 2018 and 2017 , respectively, of which $565 million had not been remitted to Treasury as of June 30, 2018 . We incurred expenses in connection with certain funding obligations under the Federal Housing Enterprises Financial Safety and Soundness Act of 1992, as amended by the Federal Housing Finance Regulatory Reform Act of 2008 (the “GSE Act”), a portion of which is attributable to Treasury’s Capital Magnet Fund. These expenses, recognized in “Other expenses, net” in our condensed consolidated statements of operations and comprehensive income, were measured as the product of 4.2 basis points and the unpaid principal balance of our total new business purchases for the respective period. We recognized $ 19 million and $ 15 million in “Other expenses, net” in connection with Treasury’s Capital Magnet Fund for the three months ended June 30, 2018 and 2017 , respectively, and $37 million and $30 million for the six months ended June 30, 2018 and 2017 , respectively, of which $37 million had not been remitted as of June 30, 2018 . In addition to the transactions with Treasury mentioned above, we purchase and sell Treasury securities in the normal course of business. As of June 30, 2018 and December 31, 2017 , we held Treasury securities with a fair value of $35.7 billion and $29.2 billion , respectively, and accrued interest receivable of $116 million and $77 million , respectively. We recognized interest income on these securities held by us of $164 million and $86 million for the three months ended June 30, 2018 and 2017 , respectively, and $293 million and $149 million for the six months ended June 30, 2018 and 2017 , respectively. Transactions with Freddie Mac As of June 30, 2018 and December 31, 2017 , we held Freddie Mac mortgage-related securities with a fair value of $543 million and $613 million , respectively, and accrued interest receivable of $2 million . We recognized interest income on these securities held by us of $ 6 million and $ 10 million for the three months ended June 30, 2018 and 2017 , respectively, and $13 million and $23 million for the six months ended June 30, 2018 and 2017 , respectively. In addition, Freddie Mac may be an investor in variable interest entities (“VIEs”) that we have consolidated, and we may be an investor in VIEs that Freddie Mac has consolidated. Freddie Mac may also be an investor in our debt securities. Transactions with FHFA The GSE Act authorizes FHFA to establish an annual assessment for regulated entities, including Fannie Mae, which is payable on a semi-annual basis (April and October), for FHFA’s costs and expenses, as well as to maintain FHFA’s working capital. We recognized FHFA assessment fees, which are recorded in “Administrative expenses” in our condensed consolidated statements of operations and comprehensive income, of $26 million for the three months ended June 30, 2018 and 2017 , respectively, and $55 million and $56 million for the six months ended June 30, 2018 and 2017 , respectively. Transactions with CSS In connection with the company we jointly own with Freddie Mac, we contributed capital to CSS of $ 35 million and $18 million for the three months ended June 30, 2018 and 2017 , respectively, and $76 million and $53 million for the six months ended June 30, 2018 and 2017 , respectively. No other transactions outside of normal business activities have occurred between us and CSS during the three and six months ended June 30, 2018 and 2017 . Income Taxes The decrease in our provision for federal income taxes for the three and six months ended June 30, 2018 as compared to the three and six months ended June 30, 2017 was the result of the Tax Cuts and Jobs Act of 2017, which reduced the federal statutory corporate income tax rate from 35% to 21% effective January 1, 2018. This decline was the primary driver of the reduction in our effective tax rate to 20.3% for the three months ended June 30, 2018 and 20.6% for the six months ended June 30, 2018 , compared with 33.2% for both the three and six months ended June 30, 2017 . Our effective tax rates for all the periods presented were different from the prevailing federal statutory rate primarily due to the benefits of our investments in housing projects eligible for low-income housing tax credits. Earnings (Loss) per Share Earnings (loss) per share (“EPS”) is presented for basic and diluted EPS. We compute basic EPS by dividing net income (loss) attributable to common stockholders by the weighted-average number of shares of common stock outstanding during the period. However, as a result of our conservatorship status and the terms of the senior preferred stock, no amounts are available to distribute as dividends to common or preferred stockholders (other than to Treasury as holder of the senior preferred stock). Weighted average common shares includes 4.6 billion shares for the periods ended June 30, 2018 and 2017 that would be issued upon the full exercise of the warrant issued to Treasury from the date the warrant was issued. The calculation of diluted EPS includes all the components of basic earnings per share, plus the dilutive effect of common stock equivalents such as convertible securities and stock options. Weighted average shares outstanding is increased to include the number of additional common shares that would have been outstanding if the dilutive potential common shares had been issued. For the six months ended June 30, 2018 and 2017 , our diluted EPS weighted average shares outstanding includes shares of common stock that would be issuable upon the conversion of 131 million shares of convertible preferred stock. For the three months ended June 30, 2018 , convertible preferred stock is not included in the calculation because a net loss attributable to common stockholders was incurred and it would have an anti-dilutive effect. New Accounting Guidance The following table updates information about our significant policies that have recently been adopted or are yet to be adopted from the information included in our 2017 Form 10-K. Standard Description Date of Adoption or Planned Adoption Impact on Consolidated Financial Statements Accounting Standards Update (“ASU”) 2016-01 , Recognition and Measurement of Financial Assets and Financial Liabilities (Subtopic 825-10) The amendment addresses certain aspects of recognition, measurement, presentation and disclosure of financial instruments. January 1, 2018 The adoption of the amendments did not have a material impact on our condensed consolidated financial statements. ASU 2016-15 , Statement of Cash Flows (Topic 230), Classification of Certain Cash Receipts and Cash Payments (a consensus of the Emerging Issues Task Force) The main objective of this update is to address the diversity in practice that currently exists in regards to how certain cash receipts and cash payments are presented and classified in the statement of cash flows under Topic 230, Statement of Cash Flows, and other Topics. January 1, 2018 This guidance was applied retrospectively to the statement of cash flows for the prior period presented. The adoption of the amendments did not have a material impact on our condensed consolidated financial statements. ASU 2016-18, Statement of Cash Flows (Topic 230) , Restricted Cash (a consensus of the Financial Accounting Standards Board (“FASB”) Emerging Issues Task Force) The amendments in this update address the diversity in the classification and presentation of changes in restricted cash on the statement of cash flows under Topic 230, Statement of Cash Flows. Specifically, this amendment dictates that the statement of cash flows should explain the change in the period of the total of cash, cash equivalents and restricted cash balances. January 1, 2018 This guidance was applied retrospectively to the statements of cash flows for the prior period presented. As a result of this adoption, the net change in restricted cash that results from transfers between cash, cash equivalents, and restricted cash will no longer be presented as an investing activity in our condensed consolidated statement of cash flows. The adoption of the amendments did not have a material impact on our condensed consolidated financial statements. ASU 2018-02, Income Statement (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income The amendments in this update allow a reclassification from accumulated other comprehensive income to retained earnings for stranded tax effects resulting from the Tax Cuts and Jobs Act. January 1, 2018 The early adoption of this guidance resulted in the reclassification of $117 million in stranded tax amounts from accumulated other comprehensive income to retained earnings. ASU 2016-13 , Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments The amendments in this update replace the incurred loss impairment methodology in current GAAP with a methodology that reflects lifetime expected credit losses and requires consideration of a broader range of reasonable and supportable information to inform credit loss estimates. January 1, 2020 We are continuing to evaluate the impact of this guidance on our condensed consolidated financial statements. We expect the greater impact of the guidance to relate to our accounting for credit losses for loans that are not individually impaired. The adoption of this guidance may increase our allowance for loan losses and decrease, perhaps substantially, our retained earnings.

Consolidations and Transfers of

Consolidations and Transfers of Financial Assets	6 Months Ended
	Jun. 30, 2018
Consolidations and Transfers of Financial Assets [Abstract]
Consolidations and Transfers of Financial Assets	Consolidations and Transfers of Financial Assets We have interests in various entities that are considered to be VIEs. The primary types of entities are securitization trusts and limited partnerships. These interests include investments in securities issued by VIEs, such as Fannie Mae MBS created pursuant to our securitization transactions and our guaranty to the entity. We consolidate the substantial majority of our single-class securitization trusts because our role as guarantor and master servicer provides us with the power to direct matters (primarily the servicing of mortgage loans) that impact the credit risk to which we are exposed. In contrast, we do not consolidate single-class securitization trusts when other organizations have the power to direct these activities. Unconsolidated VIEs We do not consolidate VIEs when we are not deemed to be the primary beneficiary. Our unconsolidated VIEs include securitization trusts and limited partnerships. The following table displays the carrying amount and classification of our assets and liabilities that relate to our involvement with unconsolidated securitization trusts. As of June 30, 2018 December 31, 2017 (Dollars in millions) Assets: Trading securities: Fannie Mae $ 1,640 $ 3,809 Non-Fannie Mae 4,925 1,580 Total trading securities 6,565 5,389 Available-for-sale securities: Fannie Mae 1,825 2,032 Non-Fannie Mae 1,322 2,062 Total available-for-sale securities 3,147 4,094 Other assets 70 74 Other liabilities (104 ) (467 ) Net carrying amount $ 9,678 $ 9,090 Our maximum exposure to loss generally represents the greater of our recorded investment in the entity or the unpaid principal balance of the assets covered by our guaranty. However, our securities issued by Fannie Mae multi-class resecuritization trusts that are not consolidated do not give rise to any additional exposure to loss as we already consolidate the underlying collateral. The maximum exposure to loss related to unconsolidated mortgage-backed trusts was approximately $14 billion and $15 billion as of June 30, 2018 and December 31, 2017 , respectively. The total assets of our unconsolidated securitization trusts were approximately $70 billion as of June 30, 2018 and December 31, 2017 . The maximum exposure to loss for our unconsolidated limited partnerships and similar legal entities, which consist of low-income housing tax credit investments, community investments and other entities, was $103 million and the related carrying value was $81 million as of June 30, 2018 . As of December 31, 2017 , the maximum exposure to loss was $105 million and the related carrying value was $82 million . The total assets of these limited partnership investments were $3.0 billion and $3.2 billion as of June 30, 2018 and December 31, 2017 , respectively. The unpaid principal balance of our multifamily loan portfolio was $275.8 billion as of June 30, 2018 . As our lending relationship does not provide us with a controlling financial interest in the borrower entity, we do not consolidate these borrowers regardless of their status as either a VIE or a voting interest entity. We have excluded these entities from our VIE disclosures. However, the disclosures we have provided in “ Note 3, Mortgage Loans ,” “ Note 4, Allowance for Loan Losses ” and “ Note 6, Financial Guarantees ” with respect to this population are consistent with the FASB’s stated objectives for the disclosures related to unconsolidated VIEs. Transfers of Financial Assets We issue Fannie Mae MBS through portfolio securitization transactions by transferring pools of mortgage loans or mortgage-related securities to one or more trusts or special purpose entities. We are considered to be the transferor when we transfer assets from our own retained mortgage portfolio in a portfolio securitization transaction. For the three months ended June 30, 2018 and 2017 , the unpaid principal balance of portfolio securitizations was $51.6 billion and $69.2 billion , respectively. For the six months ended June 30, 2018 and 2017 , the unpaid principal balance of portfolio securitizations was $115.9 billion and $126.5 billion , respectively. We retain interests from the transfer and sale of mortgage-related securities to unconsolidated single-class and multi-class portfolio securitization trusts. As of June 30, 2018 , the unpaid principal balance of retained interests was $1.6 billion and its related fair value was $2.5 billion . The unpaid principal balance of retained interests was $3.9 billion and its related fair value was $4.7 billion as of December 31, 2017 . For the three months ended June 30, 2018 and 2017 , the principal and interest received on retained interests was $128 million and $303 million , respectively. For the six months ended June 30, 2018 and 2017 , the principal and interest received on retained interests was $354 million and $560 million , respectively. Managed Loans Managed loans are on-balance sheet mortgage loans, as well as mortgage loans that we have securitized in unconsolidated portfolio securitization trusts. The unpaid principal balance of securitized loans in unconsolidated portfolio securitization trusts, which are primarily loans that are guaranteed or insured, in whole or in part, by the U.S. government, was $1.2 billion and $1.3 billion as of June 30, 2018 and December 31, 2017 , respectively. For information on our on-balance sheet mortgage loans, see “ Note 3, Mortgage Loans .”

Mortgage Loans

Mortgage Loans	6 Months Ended
	Jun. 30, 2018
Mortgage Loans on Real Estate [Abstract]
Mortgage Loans	Mortgage Loans We own single-family mortgage loans, which are secured by four or fewer residential dwelling units, and multifamily mortgage loans, which are secured by five or more residential dwelling units. We classify these loans as either held for investment (“HFI”) or held for sale (“HFS”). We report the carrying value of HFI loans at the unpaid principal balance, net of unamortized premiums and discounts, other cost basis adjustments, and an allowance for loan losses. We report the carrying value of HFS loans at the lower of cost or fair value and record valuation changes in “ Investment gains, net ” in our condensed consolidated statements of operations and comprehensive income. We define the recorded investment of HFI loans as unpaid principal balance, net of unamortized premiums and discounts, other cost basis adjustments, and accrued interest receivable. For purposes of the single-family mortgage loan disclosures in this footnote, we define “primary” class as mortgage loans that are not included in other loan classes; “government” class as mortgage loans that are guaranteed or insured, in whole or in part, by the U.S. government or one of its agencies, and that are not Alt-A; and “other” class as loans with higher-risk characteristics, such as interest-only loans and negative-amortizing loans, that are neither government nor Alt-A. The following table displays the carrying value of our mortgage loans. As of June 30, 2018 December 31, 2017 (Dollars in millions) Single-family $ 2,910,803 $ 2,890,634 Multifamily 275,797 265,069 Total unpaid principal balance of mortgage loans 3,186,600 3,155,703 Cost basis and fair value adjustments, net 38,836 41,906 Allowance for loan losses for loans held for investment (16,812 ) (19,084 ) Total mortgage loans $ 3,208,624 $ 3,178,525 The following table displays information about our redesignated mortgage loans. For the Three Months Ended June 30, For the Six Months Ended June 30, 2018 2017 2018 2017 (Dollars in millions) Carrying value of loans redesignated from HFI to HFS $ 6,235 $ 2,879 $ 13,602 $ 5,422 Carrying value of loans redesignated from HFS to HFI 12 17 30 52 Loans sold - unpaid principal balance 3,710 2,947 4,458 3,040 Realized gains on sale of mortgage loans 210 55 208 53 The recorded investment of single-family mortgage loans for which formal foreclosure proceedings are in process was $12.0 billion and $13.0 billion as of June 30, 2018 and December 31, 2017 , respectively. As a result of our various loss mitigation and foreclosure prevention efforts, we expect that a portion of the loans in the process of formal foreclosure proceedings will not ultimately foreclose. Nonaccrual Loans We discontinue accruing interest on loans when we believe collectibility of principal or interest is not reasonably assured, which for a single-family loan we have determined, based on our historical experience, to be when the loan becomes two months or more past due according to its contractual terms. Interest previously accrued but not collected is reversed through interest income at the date a loan is placed on nonaccrual status. We return a non-modified single-family loan to accrual status at the point that the borrower brings the loan current. We return a modified single-family loan to accrual status at the point that the borrower successfully makes all required payments during the trial period (generally three to four months) and the modification is made permanent. We place a multifamily loan on nonaccrual status when the loan becomes three months or more past due according to its contractual terms or is deemed to be individually impaired, unless the loan is well secured such that collectibility of principal and accrued interest is reasonably assured. We return a multifamily loan to accrual status when the borrower cures the delinquency of the loan or we otherwise determine that the loan is well secured such that collectibility is reasonably assured. Aging Analysis The following tables display an aging analysis of the total recorded investment in our HFI mortgage loans by portfolio segment and class, excluding loans for which we have elected the fair value option. As of June 30, 2018 30 - 59 Days Delinquent 60 - 89 Days Delinquent Seriously Delinquent (1) Total Delinquent Current Total Recorded Investment in Loans 90 Days or More Delinquent and Accruing Interest Recorded Investment in Nonaccrual Loans (Dollars in millions) Single-family: Primary $ 28,773 $ 6,876 $ 17,962 $ 53,611 $ 2,776,694 $ 2,830,305 $ 29 $ 28,570 Government (2) 49 17 185 251 24,068 24,319 185 — Alt-A 2,569 876 2,485 5,930 53,395 59,325 4 3,854 Other 935 313 941 2,189 15,901 18,090 3 1,417 Total single-family 32,326 8,082 21,573 61,981 2,870,058 2,932,039 221 33,841 Multifamily (3) 13 N/A 347 360 277,107 277,467 — 619 Total $ 32,339 $ 8,082 $ 21,920 $ 62,341 $ 3,147,165 $ 3,209,506 $ 221 $ 34,460 As of December 31, 2017 30 - 59 Days Delinquent 60 - 89 Days Delinquent Seriously Delinquent (1) Total Delinquent Current Total Recorded Investment in Loans 90 Days or More Delinquent and Accruing Interest Recorded Investment in Nonaccrual Loans (Dollars in millions) Single-family: Primary $ 35,582 $ 10,396 $ 23,999 $ 69,977 $ 2,732,818 $ 2,802,795 $ 87 $ 37,971 Government (2) 55 21 206 282 30,807 31,089 206 — Alt-A 3,186 1,147 3,418 7,751 59,475 67,226 5 5,094 Other 1,185 411 1,252 2,848 19,016 21,864 5 1,834 Total single-family 40,008 11,975 28,875 80,858 2,842,116 2,922,974 303 44,899 Multifamily (3) 26 N/A 276 302 266,699 267,001 — 424 Total $ 40,034 $ 11,975 $ 29,151 $ 81,160 $ 3,108,815 $ 3,189,975 $ 303 $ 45,323 __________ (1) Single-family seriously delinquent loans are loans that are 90 days or more past due or in the foreclosure process. Multifamily seriously delinquent loans are loans that are 60 days or more past due. (2) Primarily consists of reverse mortgages, which due to their nature, are not aged and are included in the current column. (3) Multifamily loans 60 - 89 days delinquent are included in the seriously delinquent column. Credit Quality Indicators The following table displays the total recorded investment in our single-family HFI loans by class and credit quality indicator, excluding loans for which we have elected the fair value option. As of June 30, 2018 (1) December 31, 2017 (1) Primary Alt-A Other Primary Alt-A Other (Dollars in millions) Estimated mark-to-market loan-to-value (“LTV”) ratio: (2) Less than or equal to 80% $ 2,516,133 $ 49,011 $ 14,537 $ 2,439,858 $ 51,903 $ 16,428 Greater than 80% and less than or equal to 90% 218,193 4,846 1,585 238,038 6,680 2,277 Greater than 90% and less than or equal to 100% 83,243 2,675 940 106,076 4,044 1,443 Greater than 100% 12,736 2,793 1,028 18,823 4,599 1,716 Total $ 2,830,305 $ 59,325 $ 18,090 $ 2,802,795 $ 67,226 $ 21,864 __________ (1) Excludes $24.3 billion and $31.1 billion as of June 30, 2018 and December 31, 2017 , respectively, of mortgage loans guaranteed or insured, in whole or in part, by the U.S. government or one of its agencies, that are not Alt-A loans. The segment class is primarily reverse mortgages for which we do not calculate an estimated mark-to-market LTV ratio. (2) The aggregate estimated mark-to-market LTV ratio is based on the unpaid principal balance of the loan as of the end of each reported period divided by the estimated current value of the property, which we calculate using an internal valuation model that estimates periodic changes in home value. The following table displays the total recorded investment in our multifamily HFI loans by credit quality indicator, excluding loans for which we have elected the fair value option. As of June 30, December 31, 2018 2017 (Dollars in millions) Credit risk profile by internally assigned grade: Non-classified $ 273,064 $ 263,416 Classified (1) 4,403 3,585 Total $ 277,467 $ 267,001 _________ (1) Represents loans classified as “Substandard,” which have a well-defined weakness that jeopardizes the timely full repayment. Loans with a weakness that makes collection or liquidation in full highly questionable and improbable based on existing conditions and values are referred to as “Doubtful.” We had no loans classified as doubtful for the periods indicated. Individually Impaired Loans Individually impaired loans include troubled debt restructurings (“TDRs”), acquired credit-impaired loans and multifamily loans that we have assessed as probable that we will not collect all contractual amounts due, regardless of whether we are currently accruing interest; excluding loans classified as HFS. The following tables display the total unpaid principal balance, recorded investment, related allowance, average recorded investment and interest income recognized for individually impaired loans. As of June 30, 2018 December 31, 2017 Unpaid Principal Balance Total Recorded Investment Related Allowance for Loan Losses Unpaid Principal Balance Total Recorded Investment Related Allowance for Loan Losses (Dollars in millions) Individually impaired loans: With related allowance recorded: Single-family: Primary $ 89,828 $ 86,148 $ (11,258 ) $ 91,194 $ 86,864 $ (11,652 ) Government 274 279 (58 ) 276 279 (56 ) Alt-A 19,098 17,475 (3,314 ) 23,077 21,045 (4,046 ) Other 6,900 6,504 (1,252 ) 8,488 8,006 (1,493 ) Total single-family 116,100 110,406 (15,882 ) 123,035 116,194 (17,247 ) Multifamily 229 230 (39 ) 279 280 (42 ) Total individually impaired loans with related allowance recorded 116,329 110,636 (15,921 ) 123,314 116,474 (17,289 ) With no related allowance recorded: (1) Single-family: Primary 15,904 15,086 — 16,027 15,158 — Government 61 56 — 66 60 — Alt-A 2,915 2,608 — 3,253 2,870 — Other 868 803 — 988 909 — Total single-family 19,748 18,553 — 20,334 18,997 — Multifamily 354 356 — 308 310 — Total individually impaired loans with no related allowance recorded 20,102 18,909 — 20,642 19,307 — Total individually impaired loans (2) $ 136,431 $ 129,545 $ (15,921 ) $ 143,956 $ 135,781 $ (17,289 ) For the Three Months Ended June 30, 2018 2017 Average Recorded Investment Total Interest Income Recognized (3) Interest Income Recognized on a Cash Basis Average Recorded Investment Total Interest Income Recognized (3) Interest Income Recognized on a Cash Basis (Dollars in millions) Individually impaired loans: With related allowance recorded: Single-family: Primary $ 88,526 $ 915 $ 109 $ 94,599 $ 955 $ 77 Government 279 9 — 295 2 — Alt-A 19,349 219 16 24,249 240 14 Other 7,265 73 6 9,419 82 5 Total single-family 115,419 1,216 131 128,562 1,279 96 Multifamily 232 1 — 259 4 — Total individually impaired loans with related allowance recorded 115,651 1,217 131 128,821 1,283 96 With no related allowance recorded: (1) Single-family: Primary 14,942 243 32 15,091 273 24 Government 57 2 — 61 1 — Alt-A 2,723 61 5 3,026 67 2 Other 857 15 1 1,016 21 1 Total single-family 18,579 321 38 19,194 362 27 Multifamily 355 1 — 284 7 — Total individually impaired loans with no related allowance recorded 18,934 322 38 19,478 369 27 Total individually impaired loans $ 134,585 $ 1,539 $ 169 $ 148,299 $ 1,652 $ 123 For the Six Months Ended June 30, 2018 2017 Average Recorded Investment Total Interest Income Recognized (3) Interest Income Recognized on a Cash Basis Average Recorded Investment Total Interest Income Recognized (3) Interest Income Recognized on a Cash Basis (Dollars in millions) Individually impaired loans: With related allowance recorded: Single-family: Primary $ 88,342 $ 1,826 $ 216 $ 96,395 $ 1,941 $ 165 Government 278 12 — 298 5 — Alt-A 20,020 431 32 24,896 489 29 Other 7,556 144 11 9,805 169 10 Total single-family 116,196 2,413 259 131,394 2,604 204 Multifamily 248 1 — 280 6 — Total individually impaired loans with related allowance recorded 116,444 2,414 259 131,674 2,610 204 With no related allowance recorded: (1) Single-family: Primary 14,988 486 58 15,050 562 47 Government 58 2 — 61 2 — Alt-A 2,781 119 9 3,056 140 5 Other 878 31 2 1,041 44 2 Total single-family 18,705 638 69 19,208 748 54 Multifamily 340 3 — 278 10 — Total individually impaired loans with no related allowance recorded 19,045 641 69 19,486 758 54 Total individually impaired loans $ 135,489 $ 3,055 $ 328 $ 151,160 $ 3,368 $ 258 __________ (1) The discounted cash flows or collateral value equals or exceeds the carrying value of the loan and, as such, no valuation allowance is required. (2) Includes single-family loans classified as TDRs with a recorded investment of $128.5 billion and $134.7 billion as of June 30, 2018 and December 31, 2017 , respectively. Includes multifamily loans classified as TDRs with a recorded investment of $211 million and $185 million as of June 30, 2018 and December 31, 2017 , respectively. (3) Total single-family interest income recognized of $1.5 billion for the three months ended June 30, 2018 consists of $1.4 billion of contractual interest and $186 million of effective yield adjustments. Total single-family interest income recognized of $1.7 billion for the three months ended June 30, 2017 consists of $1.5 billion of contractual interest and $229 million of effective yield adjustments. Total single-family interest income recognized of $3.1 billion for the six months ended June 30, 2018 consists of $2.7 billion of contractual interest and $352 million of effective yield adjustments. Total single-family interest income recognized of $3.4 billion for the six months ended June 30, 2017 consists of $2.9 billion of contractual interest and $497 million of effective yield adjustments. Troubled Debt Restructurings A modification to the contractual terms of a loan that results in granting a concession to a borrower experiencing financial difficulties is considered a TDR. In addition to formal loan modifications, we also engage in other loss mitigation activities with troubled borrowers, which include repayment plans and forbearance arrangements, both of which represent informal agreements with the borrower that do not result in the legal modification of the loan’s contractual terms. We account for these informal restructurings as a TDR if we defer more than three missed payments. We also classify loans to certain borrowers who have received bankruptcy relief as TDRs. The substantial majority of the loan modifications we complete result in term extensions, interest rate reductions or a combination of both. During the three months ended June 30, 2018 and 2017 , the average term extension of a single-family modified loan was 128 months and 155 months , respectively, and the average interest rate reduction was 0.13 and 0.67 percentage points, respectively. During the six months ended June 30, 2018 and 2017 , the average term extension of a single-family modified loan was 133 months and 154 months , respectively, and the average interest rate reduction was 0.18 and 0.80 percentage points, respectively. The following tables display the number of loans and recorded investment in loans classified as a TDR. For the Three Months Ended June 30, 2018 2017 Number of Loans Recorded Investment Number of Loans Recorded Investment (Dollars in millions) Single-family: Primary 21,820 $ 3,148 14,148 $ 1,945 Government 26 2 45 4 Alt-A 1,538 200 1,328 194 Other 285 52 271 46 Total single-family 23,669 3,402 15,792 2,189 Multifamily 2 19 3 17 Total TDRs 23,671 $ 3,421 15,795 $ 2,206 For the Six Months Ended June 30, 2018 2017 Number of Loans Recorded Investment Number of Loans Recorded Investment (Dollars in millions) Single-family: Primary 63,499 $ 9,672 31,383 $ 4,308 Government 74 6 106 10 Alt-A 3,720 483 2,893 418 Other 730 136 580 99 Total single-family 68,023 10,297 34,962 4,835 Multifamily 10 61 3 17 Total TDRs 68,033 $ 10,358 34,965 $ 4,852 The increase in loans classified as TDRs for the three and six months ended June 30, 2018 compared with the three and six months ended June 30, 2017 was primarily attributable to single-family loan modifications and other forms of loss mitigation in the areas affected by Hurricanes Harvey, Irma and Maria that resulted in a restructuring of the terms of these loans. he following tables display the number of loans and our recorded investment in these loans at the time of payment default. For purposes of this disclosure, we define loans that had a payment default as: single-family and multifamily loans with completed TDRs that liquidated during the period, either through foreclosure, deed-in-lieu of foreclosure, or a short sale; single-family loans with completed modifications that are two or more months delinquent during the period; or multifamily loans with completed modifications that are one or more months delinquent during the period. For the Three Months Ended June 30, 2018 2017 Number of Loans Recorded Investment Number of Loans Recorded Investment (Dollars in millions) Single-family: Primary 3,834 $ 554 4,238 $ 589 Government 15 2 25 3 Alt-A 588 92 616 97 Other 131 26 150 30 Total TDRs that subsequently defaulted 4,568 $ 674 5,029 $ 719 For the Six Months Ended June 30, 2018 2017 Number of Loans Recorded Investment Number of Loans Recorded Investment (Dollars in millions) Single-family: Primary 8,652 $ 1,255 8,717 $ 1,210 Government 29 4 44 5 Alt-A 1,265 201 1,230 193 Other 326 64 351 68 Total single-family 10,272 1,524 10,342 1,476 Multifamily 1 2 1 4 Total TDRs that subsequently defaulted 10,273 $ 1,526 10,343 $ 1,480

Allowance for Loan Losses

Allowance for Loan Losses	6 Months Ended
	Jun. 30, 2018
Receivables [Abstract]
Allowance for Loan Losses	Allowance for Loan Losses We maintain an allowance for loan losses for HFI loans held by Fannie Mae and loans backing Fannie Mae MBS issued from consolidated trusts. When calculating our allowance for loan losses, we consider the unpaid principal balance, net of amortized premiums and discounts, and other cost basis adjustments of HFI loans at the balance sheet date. We record charge-offs as a reduction to our allowance for loan losses at the point of foreclosure, completion of a short sale, upon the redesignation of loans from HFI to HFS or when a loan is determined to be uncollectible. We aggregate single-family HFI loans that are not individually impaired based on similar risk characteristics for purposes of estimating incurred credit losses and establishing a collective single-family loss reserve using an econometric model that derives an overall loss reserve estimate. We base our allowance methodology on historical events and trends, such as loss severity (in event of default), default rates, and recoveries from mortgage insurance contracts and other credit enhancements that provide loan level loss coverage and are either contractually attached to a loan or that were entered into contemporaneously with and in contemplation of a guaranty or loan purchase transaction. We use recent regional historical sales and appraisal information including the sales of our own foreclosed properties, to develop our loss severity estimates for all loan categories. Our allowance calculation also incorporates a loss confirmation period (the anticipated time lag between a credit loss event and the confirmation of the credit loss resulting from that event) to ensure our allowance estimate captures credit losses that have been incurred as of the balance sheet date but have not been confirmed. In addition, management performs a review of the observable data used in its estimate to ensure it is representative of prevailing economic conditions and other events existing as of the balance sheet date. Individually impaired single-family loans currently include those classified as a TDR and acquired credit-impaired loans. We consider a loan to be impaired when, based on current information, it is probable that we will not receive all amounts due, including interest, in accordance with the contractual terms of the loan agreement. When a loan has been restructured, we measure impairment using a cash flow analysis discounted at the loan’s original effective interest rate. If we expect to recover our recorded investment in an individually impaired loan through probable foreclosure of the underlying collateral, we measure impairment based on the fair value of the collateral, reduced by estimated disposal costs and adjusted for estimated proceeds from mortgage, flood, or hazard insurance or similar sources. We establish a collective allowance for all loans in our multifamily guaranty book of business that are not individually measured for impairment using an internal model that applies loss factors to loans in similar risk categories. Our loss factors are developed based on our historical default and loss severity experience. We identify multifamily loans for evaluation for impairment through a credit risk assessment process. If we determine that a multifamily loan is individually impaired, we generally measure impairment on that loan based on the fair value of the underlying collateral less estimated costs to sell the property, as we have concluded that such loans are collateral dependent. We evaluate collectively for impairment smaller-balance homogeneous multifamily loans. The following table displays changes in single-family, multifamily and total allowance for loan losses. For the Three Months Ended June 30, For the Six Months Ended June 30, 2018 2017 2018 2017 (Dollars in millions) Single-family allowance for loan losses: Beginning balance $ (18,523 ) $ (21,938 ) $ (18,849 ) $ (23,283 ) Benefit for loan losses (1) 1,270 1,185 1,192 1,605 Charge-offs 731 689 1,196 1,729 Recoveries (64 ) (146 ) (124 ) (231 ) Other (2) (16 ) (8 ) (17 ) (38 ) Ending balance $ (16,602 ) $ (20,218 ) $ (16,602 ) $ (20,218 ) Multifamily allowance for loan losses: Beginning balance $ (211 ) $ (191 ) $ (235 ) $ (182 ) Benefit for loan losses (1) — 11 20 2 Charge-offs 1 — 5 — Recoveries — (1 ) — (1 ) Ending balance $ (210 ) $ (181 ) $ (210 ) $ (181 ) Total allowance for loan losses: Beginning balance $ (18,734 ) $ (22,129 ) $ (19,084 ) $ (23,465 ) Benefit for loan losses (1) 1,270 1,196 1,212 1,607 Charge-offs 732 689 1,201 1,729 Recoveries (64 ) (147 ) (124 ) (232 ) Other (2) (16 ) (8 ) (17 ) (38 ) Ending balance $ (16,812 ) $ (20,399 ) $ (16,812 ) $ (20,399 ) __________ (1) Benefit for loan losses is included in “ Benefit for credit losses ” in our condensed consolidated statements of operations and comprehensive income. (2) Amounts represent the portion of benefit for loan losses, charge-offs and recoveries that are not a part of the allowance for loan losses. The following table displays the allowance for loan losses and recorded investment in our HFI loans by impairment or allowance methodology and portfolio segment, excluding loans for which we have elected the fair value option. As of June 30, 2018 December 31, 2017 Single-Family Multifamily Total Single-Family Multifamily Total (Dollars in millions) Allowance for loan losses by segment: Individually impaired loans (1) $ (15,882 ) $ (39 ) $ (15,921 ) $ (17,247 ) $ (42 ) $ (17,289 ) Collectively reserved loans (720 ) (171 ) (891 ) (1,602 ) (193 ) (1,795 ) Total allowance for loan losses $ (16,602 ) $ (210 ) $ (16,812 ) $ (18,849 ) $ (235 ) $ (19,084 ) Recorded investment in loans by segment: Individually impaired loans (1) $ 128,959 $ 586 $ 129,545 $ 135,191 $ 590 $ 135,781 Collectively reserved loans 2,803,080 276,881 3,079,961 2,787,783 266,411 3,054,194 Total recorded investment in loans $ 2,932,039 $ 277,467 $ 3,209,506 $ 2,922,974 $ 267,001 $ 3,189,975 __________ (1) Includes acquired credit-impaired loans.

Investments in Securities

Investments in Securities	6 Months Ended
	Jun. 30, 2018
Investments, Debt and Equity Securities [Abstract]
Investments in Securities	Investments in Securities Trading Securities Trading securities are recorded at fair value with subsequent changes in fair value recorded as “ Fair value gains (losses), net ” in our condensed consolidated statements of operations and comprehensive income. The following table displays our investments in trading securities. As of June 30, 2018 December 31, 2017 (Dollars in millions) Mortgage-related securities: Fannie Mae (1) $ 1,696 $ 3,876 Other agency 3,494 1,118 Alt-A and subprime private-label securities (1) 1,430 453 Commercial mortgage-backed securities (“CMBS”) — 9 Mortgage revenue bonds 1 1 Total mortgage-related securities 6,621 5,457 Non-mortgage-related securities: U.S. Treasury securities 35,663 29,222 Other securities 97 — Total non-mortgage-related securities 35,760 29,222 Total trading securities $ 42,381 $ 34,679 __________ (1) The increase in Alt-A and subprime private-label securities and the corresponding decrease in Fannie Mae securities from December 31, 2017 to June 30, 2018 was due to the dissolution of a Fannie Mae-wrapped private-label securities trust in the first quarter of 2018. The following table displays information about our net trading gains (losses). For the Three Months Ended June 30, For the Six Months Ended June 30, 2018 2017 2018 2017 (Dollars in millions) Net trading gains $ 21 $ 18 $ 119 $ 86 Net trading gains (losses) recognized in the period related to securities still held at period end 1 (7 ) 48 71 Available-for-Sale Securities We record available-for-sale (“AFS”) securities at fair value with unrealized gains and losses, recorded net of tax, as a component of “ Other comprehensive income (loss) ” and we recognize realized gains and losses from the sale of AFS securities in “ Investment gains, net ” in our condensed consolidated statements of operations and comprehensive income. The following table displays the gross realized gains and proceeds on sales of AFS securities. For the Three Months For the Six Months Ended June 30, Ended June 30, 2018 2017 2018 2017 (Dollars in millions) Gross realized gains $ — $ 227 $ 363 $ 230 Total proceeds (excludes initial sale of securities from new portfolio securitizations) 6 799 641 894 The following tables display the amortized cost, gross unrealized gains and losses, and fair value by major security type for AFS securities. As of June 30, 2018 Total Amortized Cost (1) Gross Unrealized Gains Gross Unrealized Losses (2) Total Fair Value (Dollars in millions) Fannie Mae $ 1,866 $ 72 $ (34 ) $ 1,904 Other agency 279 19 — 298 Alt-A and subprime private-label securities 357 292 — 649 Mortgage revenue bonds 494 16 (4 ) 506 Other mortgage-related securities 342 24 — 366 Total $ 3,338 $ 423 $ (38 ) $ 3,723 As of December 31, 2017 Total Amortized Cost (1) Gross Unrealized Gains Gross Unrealized Losses (2) Total Fair Value (Dollars in millions) Fannie Mae $ 2,044 $ 102 $ (27 ) $ 2,119 Other agency 332 25 — 357 Alt-A and subprime private-label securities 662 652 — 1,314 CMBS 15 — — 15 Mortgage revenue bonds 655 20 (4 ) 671 Other mortgage-related securities 350 17 — 367 Total $ 4,058 $ 816 $ (31 ) $ 4,843 __________ (1) Amortized cost consists of unpaid principal balance, unamortized premiums, discounts and other cost basis adjustments, as well as net other-than-temporary impairments (“OTTI”) recognized in “ Investment gains, net ” in our condensed consolidated statements of operations and comprehensive income. (2) Represents the gross unrealized losses on securities for which we have not recognized OTTI, as well as the noncredit component of OTTI and cumulative changes in fair value of securities for which we previously recognized the credit component of OTTI in “ Accumulated other comprehensive income ” in our condensed consolidated balance sheets. The following tables display additional information regarding gross unrealized losses and fair value by major security type for AFS securities in an unrealized loss position. As of June 30, 2018 Less Than 12 Consecutive Months 12 Consecutive Months or Longer Gross Unrealized Losses Fair Value Gross Unrealized Losses Fair Value (Dollars in millions) Fannie Mae $ (5 ) $ 190 $ (29 ) $ 419 Mortgage revenue bonds (1 ) 29 (3 ) 3 Total $ (6 ) $ 219 $ (32 ) $ 422 As of December 31, 2017 Less Than 12 Consecutive Months 12 Consecutive Months or Longer Gross Unrealized Losses Fair Value Gross Unrealized Losses Fair Value (Dollars in millions) Fannie Mae $ (1 ) $ 134 $ (26 ) $ 461 Mortgage revenue bonds — — (4 ) 3 Total $ (1 ) $ 134 $ (30 ) $ 464 Other-Than-Temporary Impairments The balance of the unrealized credit loss component of AFS debt securities held by us and recognized in our condensed consolidated statements of operations and comprehensive income was $733 million , $729 million and $1.1 billion as of June 30, 2018 , March 31, 2018 and December 31, 2017 , respectively. The decrease in the six months ended June 30, 2018 was primarily driven by securities no longer held in our portfolio at period end. The balance of the unrealized credit loss component of AFS debt securities held by us and recognized in our condensed consolidated statements of operations and comprehensive income was $1.8 billion as of June 30, 2017 and March 31, 2017 , and $1.9 billion as of December 31, 2016 . The decrease in the six months ended June 30, 2017 was primarily driven by securities no longer held in our portfolio at period end. Maturity Information The following table displays the amortized cost and fair value of our AFS securities by major security type and remaining contractual maturity, assuming no principal prepayments. The contractual maturity of mortgage-backed securities is not a reliable indicator of their expected life because borrowers generally have the right to prepay their obligations at any time. As of June 30, 2018 Total Amortized Cost Total Fair Value One Year or Less After One Year Through Five Years After Five Years Through Ten Years After Ten Years Amortized Cost Fair Value Amortized Cost Fair Value Amortized Cost Fair Value Amortized Cost Fair Value (Dollars in millions) Fannie Mae $ 1,866 $ 1,904 $ — $ — $ 12 $ 12 $ 80 $ 85 $ 1,774 $ 1,807 Other agency 279 298 2 2 11 11 44 47 222 238 Alt-A and subprime private-label securities 357 649 — — — — — — 357 649 Mortgage revenue bonds 494 506 4 4 33 33 61 61 396 408 Other mortgage-related securities 342 366 — — — — 6 6 336 360 Total $ 3,338 $ 3,723 $ 6 $ 6 $ 56 $ 56 $ 191 $ 199 $ 3,085 $ 3,462

Financial Guarantees

Financial Guarantees	6 Months Ended
	Jun. 30, 2018
Guarantees [Abstract]
Financial Guarantees	Financial Guarantees We recognize a guaranty obligation for our obligation to stand ready to perform on our guarantees to unconsolidated trusts and other guaranty arrangements. These off-balance sheet guarantees expose us to credit losses primarily relating to the unpaid principal balance of our unconsolidated Fannie Mae MBS and other financial guarantees. The remaining contractual terms of our guarantees range from 1 day to 34 years ; however, the actual term of each guaranty may be significantly less than the contractual term based on the prepayment characteristics of the related mortgage loans. The following table displays our maximum exposure, guaranty obligation recognized in our condensed consolidated balance sheets, and the maximum potential recovery from third parties through available credit enhancements and recourse related to our financial guarantees. As of June 30, 2018 December 31, 2017 Maximum Exposure Guaranty Obligation Maximum Recovery (1) Maximum Exposure Guaranty Obligation Maximum Recovery (1) (Dollars in millions) Unconsolidated Fannie Mae MBS $ 7,680 $ 30 $ 7,054 $ 10,876 $ 127 $ 7,340 Other guaranty arrangements (2) 13,824 133 2,320 14,265 131 2,404 Total $ 21,504 $ 163 $ 9,374 $ 25,141 $ 258 $ 9,744 __________ (1) Recoverability of such credit enhancements and recourse is subject to, among other factors, our mortgage insurers’ and financial guarantors’ ability to meet their obligations to us. For information on our mortgage insurers and financial guarantors, see “Note 13, Concentrations of Credit Risk” in our 2017 Form 10-K and “ Note 11, Concentrations of Credit Risk ” in this report. (2) Primarily consists of credit enhancements and long-term standby commitments.

Short-Term and Long-Term Debt

Short-Term and Long-Term Debt	6 Months Ended
	Jun. 30, 2018
Debt Disclosure [Abstract]
Short-Term and Long-Term Debt	Short-Term and Long-Term Debt Short-Term Debt The following table displays our outstanding short-term debt (debt with an original contractual maturity of one year or less) and weighted-average interest rates of this debt. As of June 30, 2018 December 31, 2017 Outstanding Weighted- Average Interest Rate (1) Outstanding Weighted- Average Interest Rate (1) (Dollars in millions) Short-term debt of Fannie Mae $ 25,726 1.86 % $ 33,377 1.18 % Debt of consolidated trusts 339 1.88 379 1.11 Total short-term debt $ 26,065 1.86 % $ 33,756 1.18 % __________ (1) Includes the effects of discounts, premiums and other cost basis adjustments. Intraday Line of Credit We use a secured intraday funding line of credit provided by a large financial institution. We post collateral which, in some circumstances, the secured party has the right to repledge to third parties. As this line of credit is an uncommitted intraday loan facility, we may be unable to draw on it if and when needed. The line of credit under this facility was $15.0 billion as of June 30, 2018 and December 31, 2017 . Long-Term Debt Long-term debt represents debt with an original contractual maturity of greater than one year. The following table displays our outstanding long-term debt. As of June 30, 2018 December 31, 2017 Maturities Outstanding Weighted- Average Interest Rate (1) Maturities Outstanding Weighted- Average Interest Rate (1) (Dollars in millions) Senior fixed: Benchmark notes and bonds 2018 - 2030 $ 116,563 2.28 % 2018 - 2030 $ 123,541 2.11 % Medium-term notes (2) 2018 - 2026 69,986 1.46 2018 - 2026 75,901 1.41 Other (3) 2018 - 2038 6,876 4.66 2018 - 2038 7,421 4.84 Total senior fixed 193,425 2.06 206,863 1.95 Senior floating: Medium-term notes (2) 2019 - 2020 1,175 1.86 2018 - 2020 8,425 1.36 Connecticut Avenue Securities (4) 2023 - 2030 24,589 5.66 2023 - 2030 22,527 5.18 Other (5) 2020 - 2037 354 9.00 2020 - 2037 376 6.36 Total senior floating 26,118 5.54 31,328 4.14 Subordinated debentures 2019 5,357 9.96 2019 5,106 9.93 Secured borrowings (6) 2021 - 2022 64 1.66 2021 - 2022 78 1.70 Total long-term debt of Fannie Mae (7) 224,964 2.66 243,375 2.40 Debt of consolidated trusts 2018 - 2057 3,086,460 2.84 2018 - 2057 3,052,923 2.80 Total long-term debt $ 3,311,424 2.83 % $ 3,296,298 2.77 % __________ (1) Includes the effects of discounts, premiums and other cost basis adjustments. (2) Includes long-term debt with an original contractual maturity of greater than 1 year and up to 10 years, excluding zero-coupon debt. (3) Includes other long-term debt with an original contractual maturity of greater than 10 years and foreign exchange bonds. (4) Credit risk-sharing securities that transfer a portion of the credit risk on specified pools of single-family mortgage loans to the investors in these securities, a portion of which is reported at fair value. (5) Consists of structured debt instruments that are reported at fair value. (6) Represents our remaining liability resulting from the transfer of financial assets from our condensed consolidated balance sheets that did not qualify as a sale under the accounting guidance for the transfer of financial instruments. (7) Includes unamortized discounts and premiums, other cost basis adjustments and fair value adjustments of $517 million and $752 million as of June 30, 2018 and December 31, 2017 , respectively.

Derivative Instruments

Derivative Instruments	6 Months Ended
	Jun. 30, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments	Derivative Instruments Derivative instruments are an integral part of our strategy in managing interest rate risk. Derivative instruments may be privately-negotiated, bilateral contracts, or they may be listed and traded on an exchange. We refer to our derivative transactions made pursuant to bilateral contracts as our over-the-counter (“OTC”) derivative transactions and our derivative transactions accepted for clearing by a derivatives clearing organization as our cleared derivative transactions. We typically do not settle the notional amount of our risk management derivatives; rather, notional amounts provide the basis for calculating actual payments or settlement amounts. The derivatives we use for interest rate risk management purposes consist primarily of interest rate swaps and interest rate options. We enter into various forms of credit risk sharing agreements, including credit risk transfer transactions, swap credit enhancements and mortgage insurance contracts, that we account for as derivatives. The majority of our credit-related derivatives are credit risk transfer transactions, whereby a portion of the credit risk associated with losses on a reference pool of mortgage loans is transferred to a third party. We enter into forward purchase and sale commitments that lock in the future delivery of mortgage loans and mortgage-related securities at a fixed price or yield. Certain commitments to purchase mortgage loans and purchase or sell mortgage-related securities meet the criteria of a derivative. We typically settle the notional amount of our mortgage commitments that are accounted for as derivatives. We recognize all derivatives as either assets or liabilities in our condensed consolidated balance sheets at their fair value on a trade date basis. Fair value amounts, which are netted to the extent a legal right of offset exists and is enforceable by law at the counterparty level and are inclusive of the right or obligation associated with the cash collateral posted or received, are recorded in “Other assets” or “Other liabilities” in our condensed consolidated balance sheets. See “ Note 13, Fair Value ” for additional information on derivatives recorded at fair value. We present cash flows from derivatives as operating activities in our condensed consolidated statements of cash flows. Notional and Fair Value Position of our Derivatives The following table displays the notional amount and estimated fair value of our asset and liability derivative instruments. As of June 30, 2018 As of December 31, 2017 Asset Derivatives Liability Derivatives Asset Derivatives Liability Derivatives Notional Amount Estimated Fair Value Notional Amount Estimated Fair Value Notional Amount Estimated Fair Value Notional Amount Estimated Fair Value (Dollars in millions) Risk management derivatives: Swaps: Pay-fixed $ 93,391 $ 723 $ 19,845 $ (674 ) $ 52,732 $ 772 $ 70,211 $ (2,120 ) Receive-fixed 106,673 1,123 63,209 (1,296 ) 31,671 2,391 138,852 (1,764 ) Basis 273 98 600 — 873 124 — — Foreign currency 229 37 231 (59 ) 234 59 236 (56 ) Swaptions: Pay-fixed 11,525 254 600 (2 ) 9,750 95 4,000 (20 ) Receive-fixed 500 19 7,375 (336 ) 250 13 9,250 (304 ) Other (1) 24,716 20 — (1 ) 13,240 22 7,315 (1 ) Total gross risk management derivatives 237,307 2,274 91,860 (2,368 ) 108,750 3,476 229,864 (4,265 ) Accrued interest receivable (payable) — 418 — (438 ) — 835 — (814 ) Netting adjustment (2) — (2,608 ) — 2,756 — (4,272 ) — 4,979 Total net risk management derivatives $ 237,307 $ 84 $ 91,860 $ (50 ) $ 108,750 $ 39 $ 229,864 $ (100 ) Mortgage commitment derivatives: Mortgage commitments to purchase whole loans $ 6,025 $ 20 $ 1,506 $ (1 ) $ 4,143 $ 9 $ 1,570 $ (2 ) Forward contracts to purchase mortgage-related securities 80,636 263 11,060 (16 ) 45,925 108 21,099 (21 ) Forward contracts to sell mortgage-related securities 5,498 5 134,031 (537 ) 19,320 15 85,556 (205 ) Total mortgage commitment derivatives 92,159 288 146,597 (554 ) 69,388 132 108,225 (228 ) Derivatives at fair value $ 329,466 $ 372 $ 238,457 $ (604 ) $ 178,138 $ 171 $ 338,089 $ (328 ) __________ (1) Includes credit risk transfer transactions, futures, swap credit enhancements and mortgage insurance contracts that we account for as derivatives. (2) The netting adjustment represents the effect of the legal right to offset under legally enforceable master netting arrangements to settle with the same counterparty on a net basis, including cash collateral posted and received. Cash collateral posted was $742 million and $1.4 billion as of June 30, 2018 and December 31, 2017 , respectively. Cash collateral received was $594 million and $649 million as of June 30, 2018 and December 31, 2017 , respectively. We record all derivative gains and losses, including accrued interest, in “ Fair value gains (losses), net ” in our condensed consolidated statements of operations and comprehensive income. The following table displays, by type of derivative instrument, the fair value gains and losses, net on our derivatives. For the Three Months For the Six Months Ended June 30, Ended June 30, 2018 2017 2018 2017 (Dollars in millions) Risk management derivatives: Swaps: Pay-fixed $ 967 $ (691 ) $ 3,750 $ — Receive-fixed (597 ) 639 (2,984 ) 322 Basis (3 ) 16 (26 ) 23 Foreign currency (41 ) 11 (25 ) 23 Swaptions: Pay-fixed 36 (48 ) 165 (48 ) Receive-fixed (22 ) (8 ) (38 ) (26 ) Other (16 ) 3 (4 ) (5 ) Net accrual of periodic settlements (286 ) (224 ) (501 ) (479 ) Total risk management derivatives fair value gains (losses), net 38 (302 ) 337 (190 ) Mortgage commitment derivatives fair value gains (losses), net (76 ) (192 ) 488 (272 ) Total derivatives fair value gains (losses), net $ (38 ) $ (494 ) $ 825 $ (462 ) Derivative Counterparty Credit Exposure Our derivative counterparty credit exposure relates principally to interest rate derivative contracts. We are exposed to the risk that a counterparty in a derivative transaction will default on payments due to us, which may require us to seek a replacement derivative from a different counterparty. This replacement may be at a higher cost, or we may be unable to find a suitable replacement. We manage our derivative counterparty credit exposure relating to our risk management derivative transactions mainly through enforceable master netting arrangements, which allow us to net derivative assets and liabilities with the same counterparty or clearing organization and clearing member. For our OTC derivative transactions, we require counterparties to post collateral, which may include cash, U.S. Treasury securities, agency debt and agency mortgage-related securities. See “ Note 12, Netting Arrangements ” for information on our rights to offset assets and liabilities.

Segment Reporting

Segment Reporting	6 Months Ended
	Jun. 30, 2018
Segment Reporting [Abstract]
Segment Reporting	Segment Reporting We have two reportable business segments: Single-Family and Multifamily. Results of our two business segments are intended to reflect each segment as if it were a stand-alone business. The sum of the results for our two business segments equals our condensed consolidated results of operations. The following table displays our segment results. For the Three Months Ended June 30, 2018 2017 Single-Family Multifamily Total Single-Family Multifamily Total (Dollars in millions) Net interest income (1) $ 4,723 $ 654 $ 5,377 $ 4,366 $ 636 $ 5,002 Fee and other income (2) 69 170 239 111 242 353 Net revenues 4,792 824 5,616 4,477 878 5,355 Investment gains, net (3) 252 25 277 321 64 385 Fair value gains (losses), net (4) 278 (49 ) 229 (685 ) (6 ) (691 ) Administrative expenses (649 ) (106 ) (755 ) (600 ) (86 ) (686 ) Credit-related income (expense) (5) Benefit for credit losses 1,295 1 1,296 1,255 12 1,267 Foreclosed property expense (136 ) (3 ) (139 ) (32 ) (2 ) (34 ) Total credit-related income (expense) 1,159 (2 ) 1,157 1,223 10 1,233 TCCA fees (6) (565 ) — (565 ) (518 ) — (518 ) Other expenses, net (270 ) (96 ) (366 ) (155 ) (136 ) (291 ) Income before federal income taxes 4,997 596 5,593 4,063 724 4,787 Provision for federal income taxes (1,044 ) (92 ) (1,136 ) (1,401 ) (186 ) (1,587 ) Net income $ 3,953 $ 504 $ 4,457 $ 2,662 $ 538 $ 3,200 For the Six Months Ended June 30, 2018 2017 Single-Family Multifamily Total Single-Family Multifamily Total (Dollars in millions) Net interest income (1) $ 9,284 $ 1,325 $ 10,609 $ 9,122 $ 1,226 $ 10,348 Fee and other income (2) 227 332 559 187 415 602 Net revenues 9,511 1,657 11,168 9,309 1,641 10,950 Investment gains, net (3) 494 33 527 271 105 376 Fair value gains (losses), net (4) 1,312 (38 ) 1,274 (697 ) (34 ) (731 ) Administrative expenses (1,292 ) (213 ) (1,505 ) (1,201 ) (169 ) (1,370 ) Credit-related income (expense) (5) Benefit for credit losses 1,491 22 1,513 1,655 8 1,663 Foreclosed property expense (298 ) (3 ) (301 ) (248 ) (3 ) (251 ) Total credit-related income 1,193 19 1,212 1,407 5 1,412 TCCA fees (6) (1,122 ) — (1,122 ) (1,021 ) — (1,021 ) Other expenses, net (402 ) (167 ) (569 ) (411 ) (262 ) (673 ) Income before federal income taxes 9,694 1,291 10,985 7,657 1,286 8,943 Provision for federal income taxes (2,060 ) (207 ) (2,267 ) (2,653 ) (317 ) (2,970 ) Net income $ 7,634 $ 1,084 $ 8,718 $ 5,004 $ 969 $ 5,973 __________ (1) Net interest income primarily consists of guaranty fees received as compensation for assuming and managing the credit risk on loans underlying Fannie Mae MBS held by third parties for the respective business segment, and the difference between the interest income earned on the respective business segment’s mortgage assets in our retained mortgage portfolio and the interest expense associated with the debt funding those assets. Revenues from single-family guaranty fees include revenues generated by the 10 basis point increase in guaranty fees pursuant to TCCA. (2) Single-Family fee and other income primarily consists of compensation for engaging in structured transactions and providing other lender services, and income resulting from settlement agreements resolving certain claims relating to private-label securities we purchased or that we have guaranteed. Multifamily fee and other income consists of fees associated with multifamily business activities, including yield maintenance income. (3) Investment gains and losses primarily consists of gains and losses on the sale of mortgage assets for the respective business segment. (4) Single-Family fair value gains and losses primarily consist of fair value gains and losses on risk management and mortgage commitment derivatives, trading securities and other financial instruments associated with our single-family total book of business. Multifamily fair value gains and losses primarily consist of fair value gains and losses on MBS commitment derivatives, trading securities and other financial instruments associated with our multifamily total book of business. (5) Credit-related income or expense is based on the guaranty book of business of the respective business segment and consists of the applicable segment’s benefit or provision for credit losses and foreclosed property expense on loans underlying the segment’s guaranty book of business. (6) Consists of the portion of our single-family guaranty fees that is remitted to Treasury pursuant to the TCCA.

Equity

Equity	6 Months Ended
	Jun. 30, 2018
Equity [Abstract]
Equity	Equity The following table displays the activity in other comprehensive income (loss) , net of tax, by major categories. For the Three Months Ended June 30, For the Six Months Ended June 30, 2018 2017 2018 2017 (Dollars in millions) Net income $ 4,457 $ 3,200 $ 8,718 $ 5,973 Other comprehensive income (loss), net of tax effect: Changes in net unrealized gains (losses) on AFS securities (net of tax of $1 and $6, respectively, for the three months ended and net of tax of $14 and $11, respectively, for the six months ended) 4 11 (53 ) 20 Reclassification adjustments for gains on AFS securities and other-than-temporary impairment (“OTTI”) recognized in net income (net of tax of $0 and $50, respectively, for the three months ended and $70 and $51, respectively, for the six months ended) — (92 ) (263 ) (93 ) Other (2 ) (2 ) (5 ) (4 ) Total other comprehensive income (loss) 2 (83 ) (321 ) (77 ) Total comprehensive income $ 4,459 $ 3,117 $ 8,397 $ 5,896 The following table displays our accumulated other comprehensive income , net of tax, by major categories. As of June 30, December 31, 2018 2017 (Dollars in millions) Net unrealized gains on AFS securities for which we have not recorded OTTI $ 50 $ 87 Net unrealized gains on AFS securities for which we have recorded OTTI 254 423 Other 45 43 Accumulated other comprehensive income $ 349 $ 553 The following table displays changes in accumulated other comprehensive income , net of tax. For the Three Months Ended June 30, For the Six Months Ended June 30, 2018 2017 2018 2017 AFS (1) Other Total AFS (1) Other Total AFS (1) Other Total AFS (1) Other Total (Dollars in millions) Beginning balance $ 300 $ 47 $ 347 $ 724 $ 41 $ 765 $ 510 $ 43 $ 553 $ 716 $ 43 $ 759 Reclassification of accumulated other comprehensive income to retained earnings resulting from the enactment of the Tax Cuts and Jobs Act (2) — — — — — — 110 7 117 — — — Other comprehensive income (loss) before reclassifications 4 — 4 11 — 11 (53 ) — (53 ) 20 — 20 Amounts reclassified from other comprehensive income (loss) — (2 ) (2 ) (92 ) (2 ) (94 ) (263 ) (5 ) (268 ) (93 ) (4 ) (97 ) Net other comprehensive income (loss) 4 (2 ) 2 (81 ) (2 ) (83 ) (316 ) (5 ) (321 ) (73 ) (4 ) (77 ) Ending balance $ 304 $ 45 $ 349 $ 643 $ 39 $ 682 $ 304 $ 45 $ 349 $ 643 $ 39 $ 682 __________ (1) The amounts reclassified from accumulated other comprehensive income represent the gain or loss recognized in earnings due to a sale of an AFS security or the recognition of a net impairment recognized in earnings, which are recorded in “ Investment gains, net ” in our condensed consolidated statements of operations and comprehensive income. (2) Reclassification from accumulated other comprehensive income to retained earnings of the tax effects resulting from the enactment of tax legislation on December 22, 2017 that reduced the federal corporate income tax rate from 35% to 21% effective January 1, 2018 . This amount is not included in Net other comprehensive income (loss) for the period ending June 30, 2018 .

Concentrations of Credit Risk

Concentrations of Credit Risk	6 Months Ended
	Jun. 30, 2018
Risks and Uncertainties [Abstract]
Concentrations of Credit Risk	Concentrations of Credit Risk Risk Characteristics of our Guaranty Book of Business One of the measures by which we gauge our performance risk under our guaranty is the delinquency status of the mortgage loans we hold in our retained mortgage portfolio, or in the case of mortgage-backed securities, the mortgage loans underlying the related securities. For single-family loans, management monitors the serious delinquency rate, which is the percentage of single-family loans 90 days or more past due or in the foreclosure process, and loans that have higher risk characteristics, such as high mark-to-market LTV ratios. For multifamily loans, management monitors the serious delinquency rate, which is the percentage of multifamily loans, based on unpaid principal balance, that are 60 days or more past due, and other loans that have higher risk characteristics, to determine our overall credit quality indicator. Higher risk characteristics include, but are not limited to, current debt service coverage ratio (“DSCR”) below 1.0 and high original LTV ratios. We stratify multifamily loans into different internal risk categories based on the credit risk inherent in each individual loan. For single-family and multifamily loans, we use this information, in conjunction with housing market and economic conditions, to structure our pricing and our eligibility and underwriting criteria to reflect the current risk of loans with these higher-risk characteristics, and in some cases we decide to significantly reduce our participation in riskier loan product categories. Management also uses this data together with other credit risk measures to identify key trends that guide the development of our loss mitigation strategies. The following tables display the delinquency status and serious delinquency rates for specified loan categories of our single-family conventional and total multifamily guaranty book of business. As of June 30, 2018 (1) December 31, 2017 (1) 30 Days Delinquent 60 Days Delinquent Seriously Delinquent (2) 30 Days Delinquent 60 Days Delinquent Seriously Delinquent (2) Percentage of single-family conventional guaranty book of business (3) 1.14 % 0.29 % 0.90 % 1.42 % 0.43 % 1.15 % Percentage of single-family conventional loans (4) 1.34 0.34 0.97 1.63 0.50 1.24 As of June 30, 2018 (1) December 31, 2017 (1) Percentage of Single-Family Conventional Guaranty Book of Business (3) Seriously Delinquent Rate (2) Percentage of Single-Family Conventional Guaranty Book of Business (3) Seriously Delinquent Rate (2) Estimated mark-to-market loan-to-value ratio: Greater than 100% 1 % 11.41 % 1 % 11.70 % Geographical distribution: California 19 0.36 19 0.42 Florida 6 2.51 6 3.71 New Jersey 4 1.68 4 2.15 New York 5 1.66 5 2.02 All other states 66 0.88 66 1.09 Product distribution: Alt-A 2 4.21 2 4.95 Vintages: 2004 and prior 3 3.00 4 3.28 2005-2008 6 5.54 6 6.55 2009-2018 91 0.41 90 0.53 __________ (1) Consists of the portion of our single-family conventional guaranty book of business for which we have detailed loan level information, which constituted approximately 99% of our total single-family conventional guaranty book of business as of June 30, 2018 and December 31, 2017 . (2) Consists of single-family conventional loans that were 90 days or more past due or in the foreclosure process as of June 30, 2018 and December 31, 2017 . (3) Calculated based on the aggregate unpaid principal balance of single-family conventional loans for each category divided by the aggregate unpaid principal balance of loans in our single-family conventional guaranty book of business. (4) Calculated based on the number of single-family conventional loans that were delinquent divided by the total number of loans in our single-family conventional guaranty book of business. As of June 30, 2018 (1)(2) December 31, 2017 (1)(2) 30 Days Delinquent Seriously Delinquent (3) 30 Days Delinquent Seriously Delinquent (3) Percentage of multifamily guaranty book of business 0.01 % 0.10 % 0.03 % 0.11 % As of June 30, 2018 December 31, 2017 Percentage of Multifamily Guaranty Book of Business (2) Percentage Seriously Delinquent (3)(4) Percentage of Multifamily Guaranty Book of Business (2) Percentage Seriously Delinquent (3)(4) Original LTV ratio: Greater than 80% 1 % 0.19 % 2 % 0.21 % Less than or equal to 80% 99 0.10 98 0.11 Current DSCR less than 1.0 (5) 2 3.25 2 1.96 __________ (1) Consists of the portion of our multifamily guaranty book of business for which we have detailed loan level information, which constituted approximately 99% of our total multifamily guaranty book of business as of June 30, 2018 and December 31, 2017 , excluding loans that have been defeased. (2) Calculated based on the aggregate unpaid principal balance of multifamily loans for each category divided by the aggregate unpaid principal balance of loans in our multifamily guaranty book of business. (3) Consists of multifamily loans that were 60 days or more past due as of the dates indicated. (4) Calculated based on the unpaid principal balance of multifamily loans that were seriously delinquent divided by the aggregate unpaid principal balance of multifamily loans for each category included in our guaranty book of business. (5) Our estimates of current DSCRs are based on the latest available income information for these properties. Although we use the most recently available results of our multifamily borrowers, there is a lag in reporting, which typically can range from 3 to 6 months but in some cases may be longer. Other Concentrations Mortgage Insurers. Mortgage insurance “risk in force” refers to our maximum potential loss recovery under the applicable mortgage insurance policies in force and is generally based on the loan level insurance coverage percentage and, if applicable, any aggregate pool loss limit, as specified in the policy. The following table displays our total mortgage insurance risk in force by primary and pool insurance, as well as the total risk in force mortgage insurance coverage as a percentage of the single-family guaranty book of business. As of June 30, 2018 December 31, 2017 Risk in Force Percentage of Single-Family Guaranty Book of Business Risk in Force Percentage of Single-Family Guaranty Book of Business (Dollars in millions) Mortgage insurance risk in force: Primary mortgage insurance $ 144,023 $ 137,941 Pool mortgage insurance 432 519 Total mortgage insurance risk in force $ 144,455 5% $ 138,460 5% The table below displays our mortgage insurer counterparties that provided approximately 10% or more of the risk in force mortgage insurance coverage on the single-family loans in our guaranty book of business. Percentage of Total Risk in Force Mortgage Insurance Coverage As of June 30, 2018 December 31, 2017 Counterparty: (1) Arch Capital Group Ltd. (2) 25 % 25 % Radian Guaranty, Inc. 21 21 Mortgage Guaranty Insurance Corp. 19 19 Genworth Mortgage Insurance Corp. 15 15 Essent Guaranty, Inc. 11 11 Others 9 9 Total 100 % 100 % __________ (1) Insurance coverage amounts provided for each counterparty may include coverage provided by affiliates and subsidiaries of the counterparty. (2) Arch Capital Group Ltd. is the parent company of Arch Mortgage Insurance Co. and United Guaranty Residential Insurance Co. Three of our mortgage insurer counterparties that are currently not approved to write new business are in run-off: PMI Mortgage Insurance Co. (“PMI”), Triad Guaranty Insurance Corporation (“Triad”) and Republic Mortgage Insurance Company (”RMIC”). Entering run-off may close off a source of profits and liquidity that may have otherwise assisted a mortgage insurer in paying claims under insurance policies, and could also cause the quality and speed of its claims processing to deteriorate. These three mortgage insurers provided a combined $5.4 billion , or 4% , of our risk in force mortgage insurance coverage of our single-family guaranty book of business as of June 30, 2018 . PMI and Triad have been paying only a portion of policyholder claims and deferring the remaining portion. PMI is currently paying 72.5% of claims under its mortgage insurance policies in cash and is deferring the remaining 27.5% , and Triad is currently paying 75% of claims in cash and deferring the remaining 25% . It is uncertain whether PMI or Triad will be permitted in the future to pay any remaining deferred policyholder claims and/or increase or decrease the amount of cash they pay on claims. RMIC is no longer deferring payments on policyholder claims and has paid us its previously outstanding deferred payment obligations as well as interest on those obligations; however, RMIC remains in run-off. We have counterparty credit risk relating to the potential insolvency of, or non-performance by, mortgage insurers that insure single-family loans we purchase or guarantee. There is risk that these counterparties may fail to fulfill their obligations to pay our claims under insurance policies. If we determine that it is probable that we will not collect all of our claims from one or more of our mortgage insurer counterparties, it could increase our loss reserves, which could adversely affect our results of operations, liquidity, financial condition and net worth. When we estimate the credit losses that are inherent in our mortgage loans and under the terms of our guaranty obligations we also consider the recoveries that we will receive on primary mortgage insurance, as mortgage insurance recoveries would reduce the severity of the loss associated with defaulted loans. We evaluate the financial condition of our mortgage insurer counterparties and adjust the contractually due recovery amounts to ensure that only probable losses as of the balance sheet date are included in our loss reserve estimate. As a result, if our assessment of one or more of our mortgage insurer counterparties’ ability to fulfill their respective obligations to us worsens, it could increase our combined loss reserves. As of June 30, 2018 and December 31, 2017 , the amount by which our estimated benefit from mortgage insurance reduced our combined loss reserves was $833 million and $989 million , respectively. We had outstanding receivables of $792 million recorded in “Other assets” in our condensed consolidated balance sheets as of June 30, 2018 and $858 million as of December 31, 2017 related to amounts claimed on insured, defaulted loans excluding government-insured loans. Of this amount, $47 million as of June 30, 2018 and $75 million as of December 31, 2017 was due from our mortgage servicers or sellers. We assessed the total outstanding receivables for collectibility, and they are recorded net of a valuation allowance of $568 million as of June 30, 2018 and $593 million as of December 31, 2017 . The valuation allowance reduces our claim receivable to the amount which is considered probable of collection as of June 30, 2018 and December 31, 2017 . Mortgage Servicers and Sellers. Mortgage servicers collect mortgage and escrow payments from borrowers, pay taxes and insurance costs from escrow accounts, monitor and report delinquencies, and perform other required activities on our behalf. Our mortgage servicers and sellers may also be obligated to repurchase loans or foreclosed properties, reimburse us for losses or provide other remedies under certain circumstances, such as if it is determined that the mortgage loan did not meet our underwriting or eligibility requirements, if certain loan representations and warranties are violated or if mortgage insurers rescind coverage. However, under our revised representation and warranty framework, we no longer require repurchase for loans that have breaches of certain selling representations and warranties if they have met specified criteria for relief. Our business with mortgage servicers is concentrated. The table below displays the percentage of our single-family guaranty book of business serviced by our top five depository single-family mortgage servicers and top five non-depository single-family mortgage servicers, and identifies one servicer that serviced more than 10% of our single-family guaranty book of business. Percentage of Single-Family Guaranty Book of Business As of June 30, 2018 December 31, 2017 Wells Fargo Bank, N.A. (together with its affiliates) 18 % 18 % Remaining top five depository servicers 16 17 Top five non-depository servicers 21 20 Total 55 % 55 % The table below displays the percentage of our multifamily guaranty book of business serviced by our top five multifamily mortgage servicers, and identifies two servicers that serviced 10% or more of our multifamily guaranty book of business. Percentage of Multifamily Guaranty Book of Business As of June 30, 2018 December 31, 2017 Wells Fargo Bank, N.A. (together with its affiliates) 14 % 14 % Walker & Dunlop, LLC 11 12 Remaining top five servicers 23 22 Total 48 % 48 % If a significant mortgage servicer or seller counterparty, or a number of mortgage servicers or sellers, fails to meet their obligations to us, it could increase our credit losses and credit-related expense, and adversely affect our results of operations and financial condition. For information on credit risk associated with our derivative transactions and repurchase agreements see “ Note 8, Derivative Instruments ” and “ Note 12, Netting Arrangements .”

Netting Arrangements

Netting Arrangements	6 Months Ended
	Jun. 30, 2018
Offsetting [Abstract]
Netting Arrangements	Netting Arrangements We use master netting arrangements, which allow us to offset certain financial instruments and collateral with the same counterparty, to minimize counterparty credit exposure. The tables below display information related to derivatives, securities purchased under agreements to resell or similar arrangements, and securities sold under agreements to repurchase or similar arrangements, which are subject to an enforceable master netting arrangement or similar agreement that are either offset or not offset in our condensed consolidated balance sheets. As of June 30, 2018 Gross Amount Offset (1) Net Amount Presented in our Condensed Consolidated Balance Sheets Amounts Not Offset in our Condensed Consolidated Balance Sheets Gross Amount Financial Instruments (2) Collateral (3) Net Amount (Dollars in millions) Assets: OTC risk management derivatives $ 2,672 $ (2,630 ) $ 42 $ — $ — $ 42 Cleared risk management derivatives — 22 22 — — 22 Mortgage commitment derivatives 288 — 288 (196 ) — 92 Total derivative assets 2,960 (2,608 ) 352 (4) (196 ) — 156 Securities purchased under agreements to resell or similar arrangements (5) 27,350 — 27,350 — (27,350 ) — Total assets $ 30,310 $ (2,608 ) $ 27,702 $ (196 ) $ (27,350 ) $ 156 Liabilities: OTC risk management derivatives $ (2,805 ) $ 2,757 $ (48 ) $ — $ — $ (48 ) Cleared risk management derivatives — (1 ) (1 ) — 1 — Mortgage commitment derivatives (554 ) — (554 ) 196 325 (33 ) Total derivative liabilities (3,359 ) 2,756 (603 ) (4) 196 326 (81 ) Total liabilities $ (3,359 ) $ 2,756 $ (603 ) $ 196 $ 326 $ (81 ) As of December 31, 2017 Gross Amount Offset (1) Net Amount Presented in our Condensed Consolidated Balance Sheets Amounts Not Offset in our Condensed Consolidated Balance Sheets Gross Amount Financial Instruments (2) Collateral (3) Net Amount (Dollars in millions) Assets: OTC risk management derivatives $ 2,479 $ (2,464 ) $ 15 $ — $ — $ 15 Cleared risk management derivatives 1,811 (1,808 ) 3 — — 3 Mortgage commitment derivatives 132 — 132 (117 ) (1 ) 14 Total derivative assets 4,422 (4,272 ) 150 (4) (117 ) (1 ) 32 Securities purchased under agreements to resell or similar arrangements (5) 44,670 — 44,670 — (44,670 ) — Total assets $ 49,092 $ (4,272 ) $ 44,820 $ (117 ) $ (44,671 ) $ 32 Liabilities: OTC risk management derivatives $ (3,045 ) $ 2,957 $ (88 ) $ — $ — $ (88 ) Cleared risk management derivatives (2,033 ) 2,022 (11 ) — 11 — Mortgage commitment derivatives (228 ) — (228 ) 117 93 (18 ) Total derivative liabilities (5,306 ) 4,979 (327 ) (4) 117 104 (106 ) Total liabilities $ (5,306 ) $ 4,979 $ (327 ) $ 117 $ 104 $ (106 ) __________ (1) Represents the effect of the right to offset under legally enforceable master netting arrangements to settle with the same counterparty on a net basis, including cash collateral posted and received and accrued interest. (2) Mortgage commitment derivative amounts reflect where we have recognized both an asset and a liability with the same counterparty under an enforceable master netting arrangement but we have not elected to offset the related amounts in our condensed consolidated balance sheets. (3) Represents collateral received or posted that has not been offset in our condensed consolidated balance sheets. Does not include collateral held or posted in excess of our exposure. The fair value of non-cash collateral we pledged was $2.2 billion and $747 million as of June 30, 2018 and December 31, 2017 , respectively, which the counterparty was permitted to sell or repledge. The fair value of non-cash collateral received was $27.4 billion and $44.7 billion , of which $24.9 billion and $42.5 billion could be sold or repledged as of June 30, 2018 and December 31, 2017 , respectively. None of the underlying collateral was sold or repledged as of June 30, 2018 or December 31, 2017 . (4) Excludes derivative assets of $20 million and $21 million as of June 30, 2018 and December 31, 2017 , respectively, and derivative liabilities of $1 million as of June 30, 2018 and December 31, 2017 , recognized in our condensed consolidated balance sheets that are not subject to enforceable master netting arrangements. (5) Includes $11.1 billion and $25.2 billion in securities purchased under agreements to resell classified as “Cash and cash equivalents” in our condensed consolidated balance sheets as of June 30, 2018 and December 31, 2017 . Derivative instruments are recorded at fair value and securities purchased under agreements to resell or similar arrangements are recorded at amortized cost in our condensed consolidated balance sheets. For how we determine our rights to offset the assets and liabilities presented above with the same counterparty, including collateral posted or received, see “Note 14, Netting Arrangements” in our 2017 Form 10-K.

Fair Value

Fair Value	6 Months Ended
	Jun. 30, 2018
Fair Value Disclosures [Abstract]
Fair Value	Fair Value We use fair value measurements for the initial recording of certain assets and liabilities and periodic remeasurement of certain assets and liabilities on a recurring or nonrecurring basis. Fair Value Measurement Fair value measurement guidance defines fair value, establishes a framework for measuring fair value, and sets forth disclosures around fair value measurements. This guidance applies whenever other accounting guidance requires or permits assets or liabilities to be measured at fair value. The guidance establishes a three-level fair value hierarchy that prioritizes the inputs into the valuation techniques used to measure fair value. The fair value hierarchy gives the highest priority, Level 1, to measurements based on unadjusted quoted prices in active markets for identical assets or liabilities. The next priority, Level 2, is given to measurements of assets and liabilities based on limited observable inputs or observable inputs for similar assets and liabilities. The lowest priority, Level 3, is given to measurements based on unobservable inputs. Recurring Changes in Fair Value The following tables display our assets and liabilities measured in our condensed consolidated balance sheets at fair value on a recurring basis subsequent to initial recognition, including instruments for which we have elected the fair value option. Fair Value Measurements as of June 30, 2018 Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Netting Adjustment (1) Estimated Fair Value (Dollars in millions) Recurring fair value measurements: Assets: Cash equivalents (2) $ 498 $ — $ — $ — $ 498 Trading securities: Mortgage-related securities: Fannie Mae — 1,617 79 — 1,696 Other agency — 3,494 — — 3,494 Alt-A and subprime private-label securities — 1,430 — — 1,430 Mortgage revenue bonds — — 1 — 1 Non-mortgage-related securities: U.S. Treasury securities 35,663 — — — 35,663 Other securities — 97 — — 97 Total trading securities 35,663 6,638 80 — 42,381 Available-for-sale securities: Mortgage-related securities: Fannie Mae — 1,700 204 — 1,904 Other agency — 298 — — 298 Alt-A and subprime private-label securities — 623 26 — 649 Mortgage revenue bonds — — 506 — 506 Other — 9 357 — 366 Total available-for-sale securities — 2,630 1,093 — 3,723 Mortgage loans — 8,610 1,018 — 9,628 Other assets: Risk management derivatives: Swaps — 2,291 108 — 2,399 Swaptions — 273 — — 273 Other — — 20 — 20 Netting adjustment — — — (2,608 ) (2,608 ) Mortgage commitment derivatives — 287 1 — 288 Total other assets — 2,851 129 (2,608 ) 372 Total assets at fair value $ 36,161 $ 20,729 $ 2,320 $ (2,608 ) $ 56,602 Fair Value Measurements as of June 30, 2018 Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Netting Adjustment (1) Estimated Fair Value (Dollars in millions) Liabilities: Long-term debt: Of Fannie Mae: Senior floating $ — $ 7,204 $ 354 $ — $ 7,558 Total of Fannie Mae — 7,204 354 — 7,558 Of consolidated trusts — 26,356 319 — 26,675 Total long-term debt — 33,560 673 — 34,233 Other liabilities: Risk management derivatives: Swaps — 2,466 1 — 2,467 Swaptions — 338 — — 338 Other — — 1 — 1 Netting adjustment — — — (2,756 ) (2,756 ) Mortgage commitment derivatives — 544 10 — 554 Total other liabilities — 3,348 12 (2,756 ) 604 Total liabilities at fair value $ — $ 36,908 $ 685 $ (2,756 ) $ 34,837 Fair Value Measurements as of December 31, 2017 Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Netting Adjustment (1) Estimated Fair Value (Dollars in millions) Recurring fair value measurements: Assets: Trading securities: Mortgage-related securities: Fannie Mae $ — $ 2,905 $ 971 $ — $ 3,876 Other agency — 1,083 35 — 1,118 Alt-A and subprime private-label securities — 259 194 — 453 CMBS — 9 — — 9 Mortgage revenue bonds — — 1 — 1 Non-mortgage-related securities: U.S. Treasury securities 29,222 — — — 29,222 Total trading securities 29,222 4,256 1,201 — 34,679 Available-for-sale securities: Mortgage-related securities: Fannie Mae — 1,911 208 — 2,119 Other agency — 357 — — 357 Alt-A and subprime private-label securities — 1,237 77 — 1,314 CMBS — 15 — — 15 Mortgage revenue bonds — — 671 — 671 Other — 10 357 — 367 Total available-for-sale securities — 3,530 1,313 — 4,843 Mortgage loans — 9,480 1,116 — 10,596 Other assets: Risk management derivatives: Swaps — 4,035 146 — 4,181 Swaptions — 108 — — 108 Other — — 22 — 22 Netting adjustment — — — (4,272 ) (4,272 ) Mortgage commitment derivatives — 131 1 — 132 Total other assets — 4,274 169 (4,272 ) 171 Total assets at fair value $ 29,222 $ 21,540 $ 3,799 $ (4,272 ) $ 50,289 Fair Value Measurements as of December 31, 2017 Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Netting Adjustment (1) Estimated Fair Value (Dollars in millions) Liabilities: Long-term debt: Of Fannie Mae: Senior floating $ — $ 7,810 $ 376 $ — $ 8,186 Total of Fannie Mae — 7,810 376 — 8,186 Of consolidated trusts — 29,911 582 — 30,493 Total long-term debt — 37,721 958 — 38,679 Other liabilities: Risk management derivatives: Swaps — 4,721 33 — 4,754 Swaptions — 324 — — 324 Other — — 1 — 1 Netting adjustment — — — (4,979 ) (4,979 ) Mortgage commitment derivatives — 227 1 — 228 Total other liabilities — 5,272 35 (4,979 ) 328 Total liabilities at fair value $ — $ 42,993 $ 993 $ (4,979 ) $ 39,007 __________ (1) Derivative contracts are reported on a gross basis by level. The netting adjustment represents the effect of the legal right to offset under legally enforceable master netting arrangements to settle with the same counterparty on a net basis, including cash collateral posted and received. (2) Cash equivalent are comprised of U.S. Treasuries that have a maturity at the date of acquisition of three months or less. The following tables display a reconciliation of all assets and liabilities measured at fair value on a recurring basis using significant unobservable inputs (Level 3). The tables also display gains and losses due to changes in fair value, including realized and unrealized gains and losses, recognized in our condensed consolidated statements of operations and comprehensive income for Level 3 assets and liabilities. When assets and liabilities are transferred between levels, we recognize the transfer as of the end of the period. Fair Value Measurements Using Significant Unobservable Inputs (Level 3) For the Three Months Ended June 30, 2018 Net Unrealized Gains (Losses) Included in Net Income Related to Assets and Liabilities Still Held as of June 30, 2018 (5)(6) Total Gains (Losses) (Realized/Unrealized) Balance, March 31, 2018 Included in Net Income Included in Total Other Comprehensive Income (Loss) (1) Purchases Sales Issues (3) Settlements (3) Transfers out of Level 3 Transfers into Level 3 Balance, June 30, 2018 (Dollars in millions) Trading securities: Mortgage-related: Fannie Mae $ 83 $ (5 ) $ — $ — $ — $ — $ — $ — $ 1 $ 79 $ 3 Mortgage revenue bonds 1 — — — — — — — — 1 — Total trading securities $ 84 $ (5 ) (6)(7) $ — $ — $ — $ — $ — $ — $ 1 $ 80 $ 3 Available-for-sale securities: Mortgage-related: Fannie Mae $ 202 $ 1 $ 4 $ — $ — $ — $ (3 ) $ — $ — $ 204 $ — Alt-A and subprime private-label securities 27 — — — — — (1 ) — — 26 — Mortgage revenue bonds 539 (11 ) 10 — (7 ) — (25 ) — — 506 — Other 351 7 10 — — — (11 ) — — 357 — Total available-for-sale securities $ 1,119 $ (3 ) (7)(8) $ 24 $ — $ (7 ) $ — $ (40 ) $ — $ — $ 1,093 $ — Mortgage loans $ 1,102 $ 11 (6)(7) $ — $ — $ — $ — $ (79 ) $ (51 ) $ 35 $ 1,018 $ 8 Net derivatives 133 (28 ) (6) — — — — 12 — — 117 (14 ) Long-term debt: Of Fannie Mae: Senior floating $ (357 ) $ 3 $ — $ — $ — $ — $ — $ — $ — $ (354 ) $ 3 Of consolidated trusts (462 ) 4 — — — — 21 177 (59 ) (319 ) (1 ) Total long-term debt $ (819 ) $ 7 (6) $ — $ — $ — $ — $ 21 $ 177 $ (59 ) $ (673 ) $ 2 Fair Value Measurements Using Significant Unobservable Inputs (Level 3) For the Six Months Ended June 30, 2018 Net Unrealized Gains (Losses) Included in Net Income Related to Assets and Liabilities Still Held as of June 30, 2018 (5)(6) Total Gains (Losses) (Realized/Unrealized) Balance, December 31, 2017 Included in Net Income Included in Total Other Comprehensive Income (Loss) (1) Purchases (2) Sales (2) Issues (3) Settlements (3) Transfers out of Level 3 Transfers into Level 3 Balance, June 30, 2018 (Dollars in millions) Trading securities: Mortgage-related: Fannie Mae $ 971 $ 166 $ — $ 1 $ (1,060 ) $ — $ — $ — $ 1 $ 79 $ 3 Other agency 35 (1 ) — — — — (1 ) (33 ) — — — Alt-A and subprime private-label securities 194 (85 ) — — — — (5 ) (104 ) — — — Mortgage revenue bonds 1 — — — — — — — — 1 — Total trading securities $ 1,201 $ 80 (6)(7) $ — $ 1 $ (1,060 ) $ — $ (6 ) $ (137 ) $ 1 $ 80 $ 3 Available-for-sale securities: Mortgage-related: Fannie Mae $ 208 $ 1 $ — $ — $ — $ — $ (5 ) $ — $ — $ 204 $ — Alt-A and subprime private-label securities 77 — (45 ) — — — (2 ) (4 ) — 26 — Mortgage revenue bonds 671 — (3 ) — (18 ) — (144 ) — — 506 — Other 357 14 8 — — — (22 ) — — 357 — Total available-for-sale securities $ 1,313 $ 15 (7)(8) $ (40 ) $ — $ (18 ) $ — $ (173 ) $ (4 ) $ — $ 1,093 $ — Mortgage loans $ 1,116 $ 28 (6)(7) $ — $ — $ — $ — $ (127 ) $ (87 ) $ 88 $ 1,018 $ 16 Net derivatives 134 (86 ) (6) — — — — 16 53 — 117 (37 ) Long-term debt: Of Fannie Mae: Senior floating $ (376 ) $ 22 $ — $ — $ — $ — $ — $ — $ — $ (354 ) $ 22 Of consolidated trusts (582 ) 7 — — — 1 31 331 (107 ) (319 ) (1 ) Total long-term debt $ (958 ) $ 29 (6) $ — $ — $ — $ 1 $ 31 $ 331 $ (107 ) $ (673 ) $ 21 Fair Value Measurements Using Significant Unobservable Inputs (Level 3) For the Three Months Ended June 30, 2017 Net Unrealized Gains (Losses) Included in Net Income Related to Assets and Liabilities Still Held as of June 30, 2017 (5)(6) Total Gains (Losses) (Realized/Unrealized) Balance, March 31, 2017 Included in Net Income Included in Total Other Comprehensive Income (Loss) (1) Purchases (2) Sales (2) Issues (3) Settlements (3) Transfers out of Level 3 Transfers into Level 3 (4) Balance, June 30, 2017 (Dollars in millions) Trading securities: Mortgage-related: Fannie Mae $ 856 $ 1 $ — $ 63 $ — $ — $ (2 ) $ (21 ) $ 974 $ 1,871 $ — Alt-A and subprime private-label securities 272 3 — — — — (11 ) — — 264 2 Mortgage revenue bonds 20 3 — — (21 ) — (1 ) — — 1 — Total trading securities $ 1,148 $ 7 (6)(7) $ — $ 63 $ (21 ) $ — $ (14 ) $ (21 ) $ 974 $ 2,136 $ 2 Available-for-sale securities: Mortgage-related: Fannie Mae $ 232 $ — $ (3 ) $ — $ — $ — $ (2 ) $ (21 ) $ — $ 206 $ — Alt-A and subprime private-label securities 205 — (21 ) — — — (6 ) — — 178 — Mortgage revenue bonds 1,185 34 (11 ) — (312 ) — (23 ) — — 873 — Other 417 — (19 ) — — — (18 ) — — 380 — Total available-for-sale securities $ 2,039 $ 34 (7)(8) $ (54 ) $ — $ (312 ) $ — $ (49 ) $ (21 ) $ — $ 1,637 $ — Mortgage loans $ 1,149 $ 24 (6)(7) $ — $ — $ — $ — $ (55 ) $ (21 ) $ 22 $ 1,119 $ 19 Net derivatives 113 27 (6) — — — — (16 ) — — 124 9 Long-term debt: Of Fannie Mae: Senior floating $ (350 ) $ (15 ) $ — $ — $ — $ — $ — $ — $ — $ (365 ) $ (14 ) Of consolidated trusts (214 ) (5 ) — — — — 12 22 (575 ) (760 ) (5 ) Total long-term debt $ (564 ) $ (20 ) (6) $ — $ — $ — $ — $ 12 $ 22 $ (575 ) $ (1,125 ) $ (19 ) Fair Value Measurements Using Significant Unobservable Inputs (Level 3) For the Six Months Ended June 30, 2017 Net Unrealized Gains (Losses) Included in Net Income Related to Assets and Liabilities Still Held as of June 30, 2017 (5)(6) Total Gains (Losses) (Realized/Unrealized) Balance, December 31, 2016 Included in Net Income Included in Total Other Comprehensive Income (Loss) (1) Purchases (2) Sales (2) Issues (3) Settlements (3) Transfers out of Level 3 Transfers into Level 3 (4) Balance, June 30, 2017 (Dollars in millions) Trading securities: Mortgage-related: Fannie Mae $ 835 $ 4 $ — $ 63 $ — $ — $ (5 ) $ (22 ) $ 996 $ 1,871 $ 2 Alt-A and subprime private-label securities 271 11 — — — — (18 ) — — 264 11 Mortgage revenue bonds 21 3 — — (21 ) — (2 ) — — 1 — Total trading securities $ 1,127 $ 18 (6)(7) $ — $ 63 $ (21 ) $ — $ (25 ) $ (22 ) $ 996 $ 2,136 $ 13 Available-for-sale securities: Mortgage-related: Fannie Mae $ 230 $ 1 $ (2 ) $ — $ — $ — $ (6 ) $ (47 ) $ 30 $ 206 $ — Other agency 5 — — — (1 ) — — (4 ) — — — Alt-A and subprime private-label securities 217 — (15 ) — — — (24 ) — — 178 — Mortgage revenue bonds 1,272 35 (12 ) — (324 ) — (98 ) — — 873 — Other 429 — (14 ) — — — (35 ) — — 380 — Total available-for-sale securities $ 2,153 $ 36 (7)(8) $ (43 ) $ — $ (325 ) $ — $ (163 ) $ (51 ) $ 30 $ 1,637 $ — Mortgage loans $ 1,197 $ 32 (6)(7) $ — $ — $ — $ — $ (117 ) $ (67 ) $ 74 $ 1,119 $ 16 Net derivatives 44 100 (6) — — — — (24 ) 5 (1 ) 124 — Long-term debt: Of Fannie Mae: Senior floating $ (347 ) $ (18 ) $ — $ — $ — $ — $ — $ — $ — $ (365 ) $ (18 ) Of consolidated trusts (241 ) (4 ) — — — (2 ) 19 88 (620 ) (760 ) (4 ) Total long-term debt $ (588 ) $ (22 ) (6) $ — $ — $ — $ (2 ) $ 19 $ 88 $ (620 ) $ (1,125 ) $ (22 ) __________ (1) Gains (losses) included in other comprehensive income (loss) are included in “Changes in unrealized gains on AFS securities, net of reclassification adjustments and taxes” in our condensed consolidated statements of operations and comprehensive income. (2) Purchases and sales include activity related to the consolidation and deconsolidation of assets of securitization trusts. For the first half of 2018 , includes the dissolution of a Fannie Mae-wrapped private-label securities trust. (3) Issues and settlements include activity related to the consolidation and deconsolidation of liabilities of securitization trusts. (4) Transfers of Fannie Mae trading securities into Level 3 during the second quarter and first half of 2017 consisted primarily of a Fannie Mae security backed by private-label mortgage-related securities. Prices for this security were based on inputs that were not readily available. Transfers of long-term debt of consolidated trusts into Level 3 during the second quarter and first half of 2017 consisted of securities for which prices were estimated using inputs that were not readily available. (5) Amount represents temporary changes in fair value. Amortization, accretion and OTTI are not considered unrealized and are not included in this amount. (6) Gains (losses) are included in “ Fair value gains (losses), net ” in our condensed consolidated statements of operations and comprehensive income. (7) Gains (losses) are included in “ Net interest income ” in our condensed consolidated statements of operations and comprehensive income. (8) Gains (losses) are included in “ Investment gains, net ” in our condensed consolidated statements of operations and comprehensive income. The following tables display valuation techniques and the range and the weighted average of significant unobservable inputs for our Level 3 assets and liabilities measured at fair value on a recurring basis. Fair Value Measurements as of June 30, 2018 Fair Value Significant Valuation Techniques Significant Unobservable Inputs (1) Range (1) Weighted - Average (1) (Dollars in millions) Recurring fair value measurements: Trading securities: Mortgage-related securities: Agency (2) $ 79 Various Mortgage revenue bonds 1 Various Total trading securities $ 80 Available-for-sale securities: Mortgage-related securities: Agency (2) $ 204 Various Alt-A and subprime private-label securities 26 Various Mortgage revenue bonds 389 Single Vendor Spreads (bps) 1.5 - 320.4 51.0 117 Various Total mortgage revenue bonds 506 Other 305 Discounted Cash Flow Default Rate (%) 3.8 3.8 Prepayment Speed (%) 6.5 6.5 Severity (%) 95.0 95.0 Spreads (bps) 68.5 - 400.0 399.0 52 Various Total other 357 Total available-for-sale securities $ 1,093 Net derivatives $ 107 Dealer Mark 10 Various Total net derivatives $ 117 Fair Value Measurements as of December 31, 2017 Fair Value Significant Valuation Techniques Significant Unobservable Inputs (1) Range (1) Weighted - Average (1) (Dollars in millions) Recurring fair value measurements: Trading securities: Mortgage-related securities: Agency (2) $ 971 Single Vendor Prepayment Speed (%) 0.0 - 177.0 160.0 Spreads (bps) 51.5 - 375.0 200.1 35 Various Total agency 1,006 Alt-A and subprime private-label securities 154 Consensus 40 Various Total Alt-A and subprime private-label securities 194 Mortgage revenue bonds 1 Various Total trading securities $ 1,201 Available-for-sale securities: Mortgage-related securities: Agency (2) $ 112 Single Vendor Prepayment Speed (%) 0.0 - 175.7 147.1 Spreads (bps) 150.0 - 210.0 182.3 96 Various Total agency 208 Alt-A and subprime private-label securities 77 Various Mortgage revenue bonds 475 Single Vendor Spreads (bps) (17.0 ) - 248.0 39.0 196 Various Total mortgage revenue bonds 671 Other 325 Discounted Cash Flow Prepayment Speed (%) 1.6 - 2.5 2.5 Severity (%) 50.0 - 88.0 86.6 Spreads (bps) 84.8 - 607.0 577.9 32 Various Total other 357 Total available-for-sale securities $ 1,313 Net derivatives $ 113 Dealer Mark 21 Various Total net derivatives $ 134 _________ (1) Valuation techniques for which no unobservable inputs are disclosed generally reflect the use of third-party pricing services or dealers, and the range of unobservable inputs applied by these sources is not readily available or cannot be reasonably estimated. Where we have disclosed unobservable inputs for consensus and single vendor techniques, those inputs are based on our validations performed at the security level using discounted cash flows. The prepayment speed used for trading agency securities and available-for-sale agency securities is the Public Securities Association prepayment speed, which can be greater than 100%. For all other securities, the Conditional Prepayment Rate is used as the prepayment speed, which can be between 0% and 100%. (2) Includes Fannie Mae and Freddie Mac securities. In our condensed consolidated balance sheets certain assets and liabilities are measured at fair value on a nonrecurring basis; that is, the instruments are not measured at fair value on an ongoing basis but are subject to fair value adjustments in certain circumstances (for example, when we evaluate loans for impairment). We had no Level 1 assets or liabilities held as of June 30, 2018 or December 31, 2017 that were measured at fair value on a nonrecurring basis. We held $298 million and $14 million in Level 2 assets, comprised of mortgage loans held for sale, and no Level 2 liabilities that were measured at fair value on a nonrecurring basis as of June 30, 2018 and December 31, 2017 , respectively. The following table displays valuation techniques for our Level 3 assets measured at fair value on a nonrecurring basis. The significant unobservable inputs related to these techniques primarily relate to collateral dependent valuations. The related ranges and weighted averages are not meaningful when aggregated as they vary significantly from property to property. Fair Value Measurements as of Valuation Techniques June 30, 2018 December 31, 2017 (Dollars in millions) Nonrecurring fair value measurements: Mortgage loans held for sale, at lower of cost or fair value Single Vendor $ 618 $ 1,880 Consensus 4,427 1,113 Various 1 — Total mortgage loans held for sale, at lower of cost or fair value 5,046 2,993 Single-family mortgage loans held for investment, at amortized cost Internal Model 790 1,623 Multifamily mortgage loans held for investment, at amortized cost Asset Manager Estimate 131 163 Various 24 32 Total multifamily mortgage loans held for investment, at amortized cost 155 195 Acquired property, net: (1) Single-family Accepted Offers 181 218 Appraisals 386 438 Walk Forwards 154 222 Internal Model 211 319 Various 38 113 Total single-family 970 1,310 Multifamily Various 16 19 Other assets Various 1 2 Total nonrecurring assets at fair value $ 6,978 $ 6,142 __________ (1) The most commonly used techniques in our valuation of acquired property are proprietary home price model and third-party valuations (both current and walk forward). Based on the number of properties measured as of June 30, 2018 , these methodologies comprised approximately 76% of our valuations, while accepted offers comprised approximately 19% of our valuations. Based on the number of properties measured as of December 31, 2017 , these methodologies comprised approximately 77% of our valuations, while accepted offers comprised approximately 18% of our valuations. We use valuation techniques that maximize the use of observable inputs and minimize the use of unobservable inputs. See “Note 15, Fair Value” in our 2017 Form 10-K for information on the valuation control processes and the valuation techniques we use for fair value measurement and disclosure as well as our basis for classifying these measurements as Level 1, Level 2 or Level 3 of the valuation hierarchy in more specific situations. We made no material changes to the valuation control processes or the valuation techniques for the six months ended June 30, 2018 . Fair Value of Financial Instruments The following table displays the carrying value and estimated fair value of our financial instruments. The fair value of financial instruments we disclose includes commitments to purchase multifamily and single-family mortgage loans that we do not record in our condensed consolidated balance sheets. The fair values of these commitments are included as “Mortgage loans held for investment, net of allowance for loan losses.” The disclosure excludes all non-financial instruments; therefore, the fair value of our financial assets and liabilities does not represent the underlying fair value of our total consolidated assets and liabilities. As of June 30, 2018 Carrying Quoted Prices in Active Markets for Identical Assets Significant Other Observable Inputs Significant Unobservable Inputs Netting Adjustment Estimated (Dollars in millions) Financial assets: Cash and cash equivalents and restricted cash $ 48,729 $ 37,679 $ 11,050 $ — $ — $ 48,729 Federal funds sold and securities purchased under agreements to resell or similar arrangements 16,300 — 16,300 — — 16,300 Trading securities 42,381 35,663 6,638 80 — 42,381 Available-for-sale securities 3,723 — 2,630 1,093 — 3,723 Mortgage loans held for sale 14,323 — 1,436 13,894 — 15,330 Mortgage loans held for investment, net of allowance for loan losses 3,194,301 — 2,917,541 231,082 — 3,148,623 Advances to lenders 3,901 — 3,899 2 — 3,901 Derivative assets at fair value 372 — 2,851 129 (2,608 ) 372 Guaranty assets and buy-ups 151 — — 370 — 370 Total financial assets $ 3,324,181 $ 73,342 $ 2,962,345 $ 246,650 $ (2,608 ) $ 3,279,729 Financial liabilities: Short-term debt: Of Fannie Mae $ 25,726 $ — $ 25,730 $ — $ — $ 25,730 Of consolidated trusts 339 — — 338 — 338 Long-term debt: Of Fannie Mae 224,964 — 228,853 791 — 229,644 Of consolidated trusts 3,086,460 — 2,973,785 40,988 — 3,014,773 Derivative liabilities at fair value 604 — 3,348 12 (2,756 ) 604 Guaranty obligations 163 — — 121 — 121 Total financial liabilities $ 3,338,256 $ — $ 3,231,716 $ 42,250 $ (2,756 ) $ 3,271,210 As of December 31, 2017 Carrying Quoted Prices in Active Markets for Identical Assets Significant Other Observable Inputs Significant Unobservable Inputs Netting Adjustment Estimated (Dollars in millions) Financial assets: Cash and cash equivalents and restricted cash $ 60,260 $ 35,060 $ 25,200 $ — $ — $ 60,260 Federal funds sold and securities purchased under agreements to resell or similar arrangements 19,470 — 19,470 — — 19,470 Trading securities 34,679 29,222 4,256 1,201 — 34,679 Available-for-sale securities 4,843 — 3,530 1,313 — 4,843 Mortgage loans held for sale 4,988 — 101 5,333 — 5,434 Mortgage loans held for investment, net of allowance for loan losses 3,173,537 — 2,886,470 315,719 — 3,202,189 Advances to lenders 4,938 — 4,936 2 — 4,938 Derivative assets at fair value 171 — 4,274 169 (4,272 ) 171 Guaranty assets and buy-ups 149 — — 436 — 436 Total financial assets $ 3,303,035 $ 64,282 $ 2,948,237 $ 324,173 $ (4,272 ) $ 3,332,420 Financial liabilities: Short-term debt: Of Fannie Mae $ 33,377 $ — $ 33,379 $ — $ — $ 33,379 Of consolidated trusts 379 — — 378 — 378 Long-term debt: Of Fannie Mae 243,375 — 249,780 837 — 250,617 Of consolidated trusts 3,052,923 — 3,014,250 40,683 — 3,054,933 Derivative liabilities at fair value 328 — 5,272 35 (4,979 ) 328 Guaranty obligations 258 — — 456 — 456 Total financial liabilities $ 3,330,640 $ — $ 3,302,681 $ 42,389 $ (4,979 ) $ 3,340,091 For a detailed description and classification of our financial instruments, see “Note 15, Fair Value” in our 2017 Form 10-K. Fair Value Option We elected the fair value option for our credit risk sharing debt securities issued under our CAS series issued prior to January 1, 2016 and certain loans and debt that contain embedded derivatives that would otherwise require bifurcation. Under the fair value option, we elected to carry these instruments at fair value instead of bifurcating the embedded derivative from such instruments. We elected the fair value option for all long-term structured debt instruments that are issued in response to specific investor demand and have interest rates that are based on a calculated index or formula and are economically hedged with derivatives at the time of issuance. By electing the fair value option for these instruments, we are able to eliminate the volatility in our results of operations that would otherwise result from the accounting asymmetry created by recording these structured debt instruments at cost while recording the related derivatives at fair value. Interest income for the mortgage loans is recorded in “Interest income—Mortgage loans” and interest expense for the debt instruments is recorded in “Interest expense—Long-term debt” in our condensed consolidated statements of operations and comprehensive income. The following table displays the fair value and unpaid principal balance of the financial instruments for which we have made fair value elections. As of June 30, 2018 December 31, 2017 Loans (1) Long-Term Debt of Fannie Mae Long-Term Debt of Consolidated Trusts Loans (1) Long-Term Debt of Fannie Mae Long-Term Debt of Consolidated Trusts (Dollars in millions) Fair value $ 9,628 $ 7,558 $ 26,675 $ 10,596 $ 8,186 $ 30,493 Unpaid principal balance 9,510 6,780 24,695 10,246 7,368 27,717 __________ (1) Includes nonaccrual loans with a fair value of $181 million and $227 million as of June 30, 2018 and December 31, 2017 , respectively. The difference between unpaid principal balance and the fair value of these nonaccrual loans as of June 30, 2018 and December 31, 2017 was $28 million and $46 million , respectively. Includes loans that are 90 days or more past due with a fair value of $131 million and $159 million as of June 30, 2018 and December 31, 2017 , respectively. The difference between unpaid principal balance and the fair value of these 90 or more days past due loans as of June 30, 2018 and December 31, 2017 was $22 million and $34 million , respectively. Changes in Fair Value under the Fair Value Option Election We recorded losses of $27 million and $176 million for the three and six months ended June 30, 2018 , respectively, and gains of $94 million and $136 million for the three and six months ended June 30, 2017 , respectively, from changes in the fair value of loans recorded at fair value in “Fair value gains (losses), net” in our condensed consolidated statements of operations and comprehensive income. We recorded gains of $247 million and $501 million for the three and six months ended June 30, 2018 , respectively, and losses of $288 million and $457 million for the three and six months ended June 30, 2017 , respectively, from changes in the fair value of long-term debt recorded at fair value in “Fair value gains (losses), net” in our condensed consolidated statements of operations and comprehensive income.

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies We are party to various types of legal actions and proceedings, including actions brought on behalf of various classes of claimants. We also are subject to regulatory examinations, inquiries and investigations, and other information gathering requests. In some of the matters, indeterminate amounts are sought. Modern pleading practice in the U.S. permits considerable variation in the assertion of monetary damages or other relief. Jurisdictions may permit claimants not to specify the monetary damages sought or may permit claimants to state only that the amount sought is sufficient to invoke the jurisdiction of the trial court. This variability in pleadings, together with our and our counsel’s actual experience in litigating or settling claims, leads us to conclude that the monetary relief that may be sought by plaintiffs bears little relevance to the merits or disposition value of claims. On a quarterly basis, we review relevant information about all pending legal actions and proceedings for the purpose of evaluating and revising our contingencies, accruals and disclosures. We have substantial and valid defenses to the claims in the proceedings described below and intend to defend these matters vigorously. However, legal actions and proceedings of all types are subject to many uncertain factors that generally cannot be predicted with assurance. Accordingly, the outcome of any given matter and the amount or range of potential loss at particular points in time is frequently difficult to ascertain. Uncertainties can include how fact finders will evaluate documentary evidence and the credibility and effectiveness of witness testimony, and how courts will apply the law. Disposition valuations are also subject to the uncertainty of how opposing parties and their counsel may view the evidence and applicable law. We establish an accrual only for matters when a loss is probable and we can reasonably estimate the amount of such loss. We are often unable to estimate the possible losses or ranges of losses, particularly for proceedings that are in their early stages of development, where plaintiffs seek indeterminate or unspecified damages, where there may be novel or unsettled legal questions relevant to the proceedings, or where settlement negotiations have not occurred or progressed. Given the uncertainties involved in any action or proceeding, regardless of whether we have established an accrual, the ultimate resolution of certain of these matters may be material to our operating results for a particular period, depending on, among other factors, the size of the loss or liability imposed and the level of our net income or loss for that period. In addition to the matters specifically described below, we are involved in a number of legal and regulatory proceedings that arise in the ordinary course of business that we do not expect will have a material impact on our business or financial condition. We have also advanced fees and expenses of certain current and former officers and directors in connection with various legal proceedings pursuant to our bylaws and indemnification agreements. Senior Preferred Stock Purchase Agreements Litigation A consolidated class action and three non-class action lawsuits filed by Fannie Mae and Freddie Mac shareholders are pending in the U.S. District Court for the District of Columbia against us, FHFA as our conservator, and Freddie Mac that challenge the August 2012 amendment to each company’s senior preferred stock purchase agreement with Treasury. In the consolidated class action (“ In re Fannie Mae/Freddie Mac Senior Preferred Stock Purchase Agreement Class Action Litigations ”), plaintiffs filed an amended complaint on November 1, 2017 that alleges the net worth sweep dividend provisions of the senior preferred stock that were implemented pursuant to the August 2012 amendments nullified certain of the shareholders’ rights, particularly the right to receive dividends. Plaintiffs allege claims for breach of contract, breach of the implied covenant of good faith and fair dealing, breach of fiduciary duties, and violations of Delaware and Virginia corporate law against us, FHFA and Freddie Mac, and breach of fiduciary duties claims derivatively on our and Freddie Mac’s behalf against FHFA. Plaintiffs seek to represent several classes of preferred and/or common shareholders of Fannie Mae and/or Freddie Mac who held stock as of the public announcement of the August 2012 amendments. Plaintiffs seek unspecified damages, equitable and injunctive relief, and costs and expenses, including attorneys’ fees. The defendants moved to dismiss the amended complaint on January 10, 2018. In two of the non-class action suits, Arrowood Indemnity Company v. Fannie Mae and Fairholme Funds v. FHFA , the plaintiffs, Fannie Mae and Freddie Mac preferred shareholders, filed amended complaints on November 1, 2017 against us, FHFA as our conservator, the Director of FHFA (in his official capacity) and Freddie Mac alleging that the net worth sweep dividend provisions nullified certain rights of the preferred shareholders, particularly the right to receive dividends, and exceeded FHFA’s statutory authority. Plaintiffs bring claims for breach of contract, breach of the implied covenant of good faith and fair dealing, breach of fiduciary duties and violations of Delaware and Virginia corporate law. They also assert claims for violation of the Administrative Procedure Act against FHFA. Plaintiffs seek damages, equitable and injunctive relief, and costs and expenses, including attorneys’ fees. Defendants moved to dismiss both amended complaints on January 10, 2018. On May 21, 2018, another Fannie Mae and Freddie Mac shareholder filed a pro se complaint for declaratory relief and compensatory damages against Fannie Mae (including certain members of its Board of Directors), Freddie Mac (including certain members of its Board of Directors) and FHFA, as conservator. Plaintiff in that case, Angel v. Federal Home Loan Mortgage Corporation , asserts claims for breach of contract, breach of implied covenants of good faith and fair dealing, and aiding and abetting the federal government in avoiding an alleged implicit guarantee of dividend payments. Defendants moved to dismiss the complaint on July 12, 2018. On August 2, 2017, shareholder David J. Voacolo filed a lawsuit, Voacolo v. Fannie Mae , in the U.S. District Court for the District of New Jersey against Fannie Mae and the United States alleging that the net worth sweep dividend provisions of the senior preferred stock that were implemented pursuant to the August 2012 amendments to the senior preferred stock purchase agreements were a violation of due process and an illegal exaction. Plaintiff seeks damages only. Defendants filed motions to dismiss on March 26, 2018. On May 4, 2018, the court granted defendants’ motions to dismiss. Given the stage of these lawsuits, the substantial and novel legal questions that remain, and our substantial defenses, we are currently unable to estimate the reasonably possible loss or range of loss arising from this litigation.

Summary of Significant Accoun21

Summary of Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2018
Accounting Policies [Abstract]
Basis of Presentation [Policy Text Block]	Basis of Presentation The accompanying unaudited interim condensed consolidated financial statements have been prepared in accordance with generally accepted accounting principles in the United States of America (“GAAP”) for interim financial information and with the SEC’s instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and note disclosures required by GAAP for complete consolidated financial statements. In the opinion of management, all adjustments of a normal recurring nature considered necessary for a fair presentation have been included. The accompanying condensed consolidated financial statements include our accounts as well as the accounts of other entities in which we have a controlling financial interest. All intercompany accounts and transactions have been eliminated. To conform to our current period presentation, we have reclassified certain amounts reported in our prior periods’ condensed consolidated financial statements. Results for the three and six months ended June 30, 2018 may not necessarily be indicative of the results for the year ending December 31, 2018 .
Use of Estimates, Policy [Policy Text Block]	Use of Estimates Preparing condensed consolidated financial statements in accordance with GAAP requires management to make estimates and assumptions that affect our reported amounts of assets and liabilities, and disclosure of contingent assets and liabilities as of the dates of our condensed consolidated financial statements, as well as our reported amounts of revenues and expenses during the reporting periods. Management has made significant estimates in a variety of areas including, but not limited to, valuation of certain financial instruments and allowance for loan losses. Actual results could be different from these estimates.
Earnings Per Share, Policy [Policy Text Block]	Earnings (loss) per share (“EPS”) is presented for basic and diluted EPS. We compute basic EPS by dividing net income (loss) attributable to common stockholders by the weighted-average number of shares of common stock outstanding during the period. However, as a result of our conservatorship status and the terms of the senior preferred stock, no amounts are available to distribute as dividends to common or preferred stockholders (other than to Treasury as holder of the senior preferred stock). Weighted average common shares includes 4.6 billion shares for the periods ended June 30, 2018 and 2017 that would be issued upon the full exercise of the warrant issued to Treasury from the date the warrant was issued. The calculation of diluted EPS includes all the components of basic earnings per share, plus the dilutive effect of common stock equivalents such as convertible securities and stock options. Weighted average shares outstanding is increased to include the number of additional common shares that would have been outstanding if the dilutive potential common shares had been issued. For the six months ended June 30, 2018 and 2017 , our diluted EPS weighted average shares outstanding includes shares of common stock that would be issuable upon the conversion of 131 million shares of convertible preferred stock. For the three months ended June 30, 2018 , convertible preferred stock is not included in the calculation because a net loss attributable to common stockholders was incurred and it would have an anti-dilutive effect.
New Accounting Pronouncements, Policy [Policy Text Block]	New Accounting Guidance The following table updates information about our significant policies that have recently been adopted or are yet to be adopted from the information included in our 2017 Form 10-K. Standard Description Date of Adoption or Planned Adoption Impact on Consolidated Financial Statements Accounting Standards Update (“ASU”) 2016-01 , Recognition and Measurement of Financial Assets and Financial Liabilities (Subtopic 825-10) The amendment addresses certain aspects of recognition, measurement, presentation and disclosure of financial instruments. January 1, 2018 The adoption of the amendments did not have a material impact on our condensed consolidated financial statements. ASU 2016-15 , Statement of Cash Flows (Topic 230), Classification of Certain Cash Receipts and Cash Payments (a consensus of the Emerging Issues Task Force) The main objective of this update is to address the diversity in practice that currently exists in regards to how certain cash receipts and cash payments are presented and classified in the statement of cash flows under Topic 230, Statement of Cash Flows, and other Topics. January 1, 2018 This guidance was applied retrospectively to the statement of cash flows for the prior period presented. The adoption of the amendments did not have a material impact on our condensed consolidated financial statements. ASU 2016-18, Statement of Cash Flows (Topic 230) , Restricted Cash (a consensus of the Financial Accounting Standards Board (“FASB”) Emerging Issues Task Force) The amendments in this update address the diversity in the classification and presentation of changes in restricted cash on the statement of cash flows under Topic 230, Statement of Cash Flows. Specifically, this amendment dictates that the statement of cash flows should explain the change in the period of the total of cash, cash equivalents and restricted cash balances. January 1, 2018 This guidance was applied retrospectively to the statements of cash flows for the prior period presented. As a result of this adoption, the net change in restricted cash that results from transfers between cash, cash equivalents, and restricted cash will no longer be presented as an investing activity in our condensed consolidated statement of cash flows. The adoption of the amendments did not have a material impact on our condensed consolidated financial statements. ASU 2018-02, Income Statement (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income The amendments in this update allow a reclassification from accumulated other comprehensive income to retained earnings for stranded tax effects resulting from the Tax Cuts and Jobs Act. January 1, 2018 The early adoption of this guidance resulted in the reclassification of $117 million in stranded tax amounts from accumulated other comprehensive income to retained earnings. ASU 2016-13 , Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments The amendments in this update replace the incurred loss impairment methodology in current GAAP with a methodology that reflects lifetime expected credit losses and requires consideration of a broader range of reasonable and supportable information to inform credit loss estimates. January 1, 2020 We are continuing to evaluate the impact of this guidance on our condensed consolidated financial statements. We expect the greater impact of the guidance to relate to our accounting for credit losses for loans that are not individually impaired. The adoption of this guidance may increase our allowance for loan losses and decrease, perhaps substantially, our retained earnings.

Consolidations and Transfers 22

Consolidations and Transfers of Financial Assets (Policies)	6 Months Ended
	Jun. 30, 2018
Consolidations and Transfers of Financial Assets [Abstract]
Consolidations, Policy [Policy Text Block]	We have interests in various entities that are considered to be VIEs. The primary types of entities are securitization trusts and limited partnerships. These interests include investments in securities issued by VIEs, such as Fannie Mae MBS created pursuant to our securitization transactions and our guaranty to the entity. We consolidate the substantial majority of our single-class securitization trusts because our role as guarantor and master servicer provides us with the power to direct matters (primarily the servicing of mortgage loans) that impact the credit risk to which we are exposed. In contrast, we do not consolidate single-class securitization trusts when other organizations have the power to direct these activities. Unconsolidated VIEs We do not consolidate VIEs when we are not deemed to be the primary beneficiary. Our unconsolidated VIEs include securitization trusts and limited partnerships.
Transfers and Servicing of Financial Assets, Policy [Policy Text Block]	Transfers of Financial Assets We issue Fannie Mae MBS through portfolio securitization transactions by transferring pools of mortgage loans or mortgage-related securities to one or more trusts or special purpose entities. We are considered to be the transferor when we transfer assets from our own retained mortgage portfolio in a portfolio securitization transaction.

Mortgage Loans (Policies)

Mortgage Loans (Policies)	6 Months Ended
	Jun. 30, 2018
Mortgage Loans on Real Estate [Abstract]
Finance, Loan and Lease Receivables, Held-for-investment, Policy [Policy Text Block]	We report the carrying value of HFI loans at the unpaid principal balance, net of unamortized premiums and discounts, other cost basis adjustments, and an allowance for loan losses. We define the recorded investment of HFI loans as unpaid principal balance, net of unamortized premiums and discounts, other cost basis adjustments, and accrued interest receivable.
Finance, Loan and Lease Receivables, Held-for-sale, Policy [Policy Text Block]	We report the carrying value of HFS loans at the lower of cost or fair value and record valuation changes in “ Investment gains, net ” in our condensed consolidated statements of operations and comprehensive income.
Nonaccrual Loans [Policy Text Block]	We discontinue accruing interest on loans when we believe collectibility of principal or interest is not reasonably assured, which for a single-family loan we have determined, based on our historical experience, to be when the loan becomes two months or more past due according to its contractual terms. Interest previously accrued but not collected is reversed through interest income at the date a loan is placed on nonaccrual status. We return a non-modified single-family loan to accrual status at the point that the borrower brings the loan current. We return a modified single-family loan to accrual status at the point that the borrower successfully makes all required payments during the trial period (generally three to four months) and the modification is made permanent. We place a multifamily loan on nonaccrual status when the loan becomes three months or more past due according to its contractual terms or is deemed to be individually impaired, unless the loan is well secured such that collectibility of principal and accrued interest is reasonably assured. We return a multifamily loan to accrual status when the borrower cures the delinquency of the loan or we otherwise determine that the loan is well secured such that collectibility is reasonably assured.
Troubled Debt Restructurings [Policy Text Block]	A modification to the contractual terms of a loan that results in granting a concession to a borrower experiencing financial difficulties is considered a TDR.

Allowance for Loan Losses (Poli

Allowance for Loan Losses (Policies)	6 Months Ended
	Jun. 30, 2018
Receivables [Abstract]
Allowance for Loan Losses [Policy Text Block]	We maintain an allowance for loan losses for HFI loans held by Fannie Mae and loans backing Fannie Mae MBS issued from consolidated trusts. When calculating our allowance for loan losses, we consider the unpaid principal balance, net of amortized premiums and discounts, and other cost basis adjustments of HFI loans at the balance sheet date. We record charge-offs as a reduction to our allowance for loan losses at the point of foreclosure, completion of a short sale, upon the redesignation of loans from HFI to HFS or when a loan is determined to be uncollectible. We aggregate single-family HFI loans that are not individually impaired based on similar risk characteristics for purposes of estimating incurred credit losses and establishing a collective single-family loss reserve using an econometric model that derives an overall loss reserve estimate. We base our allowance methodology on historical events and trends, such as loss severity (in event of default), default rates, and recoveries from mortgage insurance contracts and other credit enhancements that provide loan level loss coverage and are either contractually attached to a loan or that were entered into contemporaneously with and in contemplation of a guaranty or loan purchase transaction. We use recent regional historical sales and appraisal information including the sales of our own foreclosed properties, to develop our loss severity estimates for all loan categories. Our allowance calculation also incorporates a loss confirmation period (the anticipated time lag between a credit loss event and the confirmation of the credit loss resulting from that event) to ensure our allowance estimate captures credit losses that have been incurred as of the balance sheet date but have not been confirmed. In addition, management performs a review of the observable data used in its estimate to ensure it is representative of prevailing economic conditions and other events existing as of the balance sheet date. Individually impaired single-family loans currently include those classified as a TDR and acquired credit-impaired loans. We consider a loan to be impaired when, based on current information, it is probable that we will not receive all amounts due, including interest, in accordance with the contractual terms of the loan agreement. When a loan has been restructured, we measure impairment using a cash flow analysis discounted at the loan’s original effective interest rate. If we expect to recover our recorded investment in an individually impaired loan through probable foreclosure of the underlying collateral, we measure impairment based on the fair value of the collateral, reduced by estimated disposal costs and adjusted for estimated proceeds from mortgage, flood, or hazard insurance or similar sources. We establish a collective allowance for all loans in our multifamily guaranty book of business that are not individually measured for impairment using an internal model that applies loss factors to loans in similar risk categories. Our loss factors are developed based on our historical default and loss severity experience. We identify multifamily loans for evaluation for impairment through a credit risk assessment process. If we determine that a multifamily loan is individually impaired, we generally measure impairment on that loan based on the fair value of the underlying collateral less estimated costs to sell the property, as we have concluded that such loans are collateral dependent. We evaluate collectively for impairment smaller-balance homogeneous multifamily loans.

Investment in Securities (Polic

Investment in Securities (Policies)	6 Months Ended
	Jun. 30, 2018
Investments, Debt and Equity Securities [Abstract]
Trading Securities, Policy [Policy Text Block]	Trading Securities Trading securities are recorded at fair value with subsequent changes in fair value recorded as “ Fair value gains (losses), net ” in our condensed consolidated statements of operations and comprehensive income.
Available-for-sale Securities, Policy [Policy Text Block]	Available-for-Sale Securities We record available-for-sale (“AFS”) securities at fair value with unrealized gains and losses, recorded net of tax, as a component of “ Other comprehensive income (loss) ” and we recognize realized gains and losses from the sale of AFS securities in “ Investment gains, net ” in our condensed consolidated statements of operations and comprehensive income.

Derivative Instruments (Policie

Derivative Instruments (Policies)	6 Months Ended
	Jun. 30, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivatives, Policy [Policy Text Block]	We recognize all derivatives as either assets or liabilities in our condensed consolidated balance sheets at their fair value on a trade date basis. Fair value amounts, which are netted to the extent a legal right of offset exists and is enforceable by law at the counterparty level and are inclusive of the right or obligation associated with the cash collateral posted or received, are recorded in “Other assets” or “Other liabilities” in our condensed consolidated balance sheets. See “ Note 13, Fair Value ” for additional information on derivatives recorded at fair value. We present cash flows from derivatives as operating activities in our condensed consolidated statements of cash flows.

Segment Reporting (Policies)

Segment Reporting (Policies)	6 Months Ended
	Jun. 30, 2018
Segment Reporting [Abstract]
Segment Reporting, Policy [Policy Text Block]	We have two reportable business segments: Single-Family and Multifamily. Results of our two business segments are intended to reflect each segment as if it were a stand-alone business.

Netting Arrangements (Policies)

Netting Arrangements (Policies)	6 Months Ended
	Jun. 30, 2018
Offsetting [Abstract]
Derivatives, Offsetting Policy [Policy Text Block]	Derivative instruments are recorded at fair value and securities purchased under agreements to resell or similar arrangements are recorded at amortized cost in our condensed consolidated balance sheets. For how we determine our rights to offset the assets and liabilities presented above with the same counterparty, including collateral posted or received, see “Note 14, Netting Arrangements” in our 2017 Form 10-K.

Fair Value (Policies)

Fair Value (Policies)	6 Months Ended
	Jun. 30, 2018
Fair Value Disclosures [Abstract]
Fair Value Measurement, Policy [Policy Text Block]	Fair Value Measurement Fair value measurement guidance defines fair value, establishes a framework for measuring fair value, and sets forth disclosures around fair value measurements. This guidance applies whenever other accounting guidance requires or permits assets or liabilities to be measured at fair value. The guidance establishes a three-level fair value hierarchy that prioritizes the inputs into the valuation techniques used to measure fair value. The fair value hierarchy gives the highest priority, Level 1, to measurements based on unadjusted quoted prices in active markets for identical assets or liabilities. The next priority, Level 2, is given to measurements of assets and liabilities based on limited observable inputs or observable inputs for similar assets and liabilities. The lowest priority, Level 3, is given to measurements based on unobservable inputs. Fair Value Option We elected the fair value option for our credit risk sharing debt securities issued under our CAS series issued prior to January 1, 2016 and certain loans and debt that contain embedded derivatives that would otherwise require bifurcation. Under the fair value option, we elected to carry these instruments at fair value instead of bifurcating the embedded derivative from such instruments. We elected the fair value option for all long-term structured debt instruments that are issued in response to specific investor demand and have interest rates that are based on a calculated index or formula and are economically hedged with derivatives at the time of issuance. By electing the fair value option for these instruments, we are able to eliminate the volatility in our results of operations that would otherwise result from the accounting asymmetry created by recording these structured debt instruments at cost while recording the related derivatives at fair value. Interest income for the mortgage loans is recorded in “Interest income—Mortgage loans” and interest expense for the debt instruments is recorded in “Interest expense—Long-term debt” in our condensed consolidated statements of operations and comprehensive income.

Commitments and Contingencies (

Commitments and Contingencies (Policies)	6 Months Ended
	Jun. 30, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies, Policy [Policy Text Block]	We establish an accrual only for matters when a loss is probable and we can reasonably estimate the amount of such loss. On a quarterly basis, we review relevant information about all pending legal actions and proceedings for the purpose of evaluating and revising our contingencies, accruals and disclosures.

Consolidations and Transfers 31

Consolidations and Transfers of Financial Assets (Tables)	6 Months Ended
	Jun. 30, 2018
Consolidations and Transfers of Financial Assets [Abstract]
Unconsolidated Variable Interest Entities [Table Text Block]	The following table displays the carrying amount and classification of our assets and liabilities that relate to our involvement with unconsolidated securitization trusts. As of June 30, 2018 December 31, 2017 (Dollars in millions) Assets: Trading securities: Fannie Mae $ 1,640 $ 3,809 Non-Fannie Mae 4,925 1,580 Total trading securities 6,565 5,389 Available-for-sale securities: Fannie Mae 1,825 2,032 Non-Fannie Mae 1,322 2,062 Total available-for-sale securities 3,147 4,094 Other assets 70 74 Other liabilities (104 ) (467 ) Net carrying amount $ 9,678 $ 9,090

Mortgage Loans (Tables)

Mortgage Loans (Tables)	6 Months Ended
	Jun. 30, 2018
Mortgage Loans on Real Estate [Line Items]
Loans in Mortgage Portfolio [Table Text Block]	The following table displays the carrying value of our mortgage loans. As of June 30, 2018 December 31, 2017 (Dollars in millions) Single-family $ 2,910,803 $ 2,890,634 Multifamily 275,797 265,069 Total unpaid principal balance of mortgage loans 3,186,600 3,155,703 Cost basis and fair value adjustments, net 38,836 41,906 Allowance for loan losses for loans held for investment (16,812 ) (19,084 ) Total mortgage loans $ 3,208,624 $ 3,178,525 The following table displays information about our redesignated mortgage loans. For the Three Months Ended June 30, For the Six Months Ended June 30, 2018 2017 2018 2017 (Dollars in millions) Carrying value of loans redesignated from HFI to HFS $ 6,235 $ 2,879 $ 13,602 $ 5,422 Carrying value of loans redesignated from HFS to HFI 12 17 30 52 Loans sold - unpaid principal balance 3,710 2,947 4,458 3,040 Realized gains on sale of mortgage loans 210 55 208 53 The following table displays the allowance for loan losses and recorded investment in our HFI loans by impairment or allowance methodology and portfolio segment, excluding loans for which we have elected the fair value option. As of June 30, 2018 December 31, 2017 Single-Family Multifamily Total Single-Family Multifamily Total (Dollars in millions) Allowance for loan losses by segment: Individually impaired loans (1) $ (15,882 ) $ (39 ) $ (15,921 ) $ (17,247 ) $ (42 ) $ (17,289 ) Collectively reserved loans (720 ) (171 ) (891 ) (1,602 ) (193 ) (1,795 ) Total allowance for loan losses $ (16,602 ) $ (210 ) $ (16,812 ) $ (18,849 ) $ (235 ) $ (19,084 ) Recorded investment in loans by segment: Individually impaired loans (1) $ 128,959 $ 586 $ 129,545 $ 135,191 $ 590 $ 135,781 Collectively reserved loans 2,803,080 276,881 3,079,961 2,787,783 266,411 3,054,194 Total recorded investment in loans $ 2,932,039 $ 277,467 $ 3,209,506 $ 2,922,974 $ 267,001 $ 3,189,975 __________ (1) Includes acquired credit-impaired loans.
Aging Analysis [Table Text Block]	The following tables display an aging analysis of the total recorded investment in our HFI mortgage loans by portfolio segment and class, excluding loans for which we have elected the fair value option. As of June 30, 2018 30 - 59 Days Delinquent 60 - 89 Days Delinquent Seriously Delinquent (1) Total Delinquent Current Total Recorded Investment in Loans 90 Days or More Delinquent and Accruing Interest Recorded Investment in Nonaccrual Loans (Dollars in millions) Single-family: Primary $ 28,773 $ 6,876 $ 17,962 $ 53,611 $ 2,776,694 $ 2,830,305 $ 29 $ 28,570 Government (2) 49 17 185 251 24,068 24,319 185 — Alt-A 2,569 876 2,485 5,930 53,395 59,325 4 3,854 Other 935 313 941 2,189 15,901 18,090 3 1,417 Total single-family 32,326 8,082 21,573 61,981 2,870,058 2,932,039 221 33,841 Multifamily (3) 13 N/A 347 360 277,107 277,467 — 619 Total $ 32,339 $ 8,082 $ 21,920 $ 62,341 $ 3,147,165 $ 3,209,506 $ 221 $ 34,460 As of December 31, 2017 30 - 59 Days Delinquent 60 - 89 Days Delinquent Seriously Delinquent (1) Total Delinquent Current Total Recorded Investment in Loans 90 Days or More Delinquent and Accruing Interest Recorded Investment in Nonaccrual Loans (Dollars in millions) Single-family: Primary $ 35,582 $ 10,396 $ 23,999 $ 69,977 $ 2,732,818 $ 2,802,795 $ 87 $ 37,971 Government (2) 55 21 206 282 30,807 31,089 206 — Alt-A 3,186 1,147 3,418 7,751 59,475 67,226 5 5,094 Other 1,185 411 1,252 2,848 19,016 21,864 5 1,834 Total single-family 40,008 11,975 28,875 80,858 2,842,116 2,922,974 303 44,899 Multifamily (3) 26 N/A 276 302 266,699 267,001 — 424 Total $ 40,034 $ 11,975 $ 29,151 $ 81,160 $ 3,108,815 $ 3,189,975 $ 303 $ 45,323 __________ (1) Single-family seriously delinquent loans are loans that are 90 days or more past due or in the foreclosure process. Multifamily seriously delinquent loans are loans that are 60 days or more past due. (2) Primarily consists of reverse mortgages, which due to their nature, are not aged and are included in the current column. (3) Multifamily loans 60 - 89 days delinquent are included in the seriously delinquent column.
Individually Impaired Loans [Table Text Block]	The following tables display the total unpaid principal balance, recorded investment, related allowance, average recorded investment and interest income recognized for individually impaired loans. As of June 30, 2018 December 31, 2017 Unpaid Principal Balance Total Recorded Investment Related Allowance for Loan Losses Unpaid Principal Balance Total Recorded Investment Related Allowance for Loan Losses (Dollars in millions) Individually impaired loans: With related allowance recorded: Single-family: Primary $ 89,828 $ 86,148 $ (11,258 ) $ 91,194 $ 86,864 $ (11,652 ) Government 274 279 (58 ) 276 279 (56 ) Alt-A 19,098 17,475 (3,314 ) 23,077 21,045 (4,046 ) Other 6,900 6,504 (1,252 ) 8,488 8,006 (1,493 ) Total single-family 116,100 110,406 (15,882 ) 123,035 116,194 (17,247 ) Multifamily 229 230 (39 ) 279 280 (42 ) Total individually impaired loans with related allowance recorded 116,329 110,636 (15,921 ) 123,314 116,474 (17,289 ) With no related allowance recorded: (1) Single-family: Primary 15,904 15,086 — 16,027 15,158 — Government 61 56 — 66 60 — Alt-A 2,915 2,608 — 3,253 2,870 — Other 868 803 — 988 909 — Total single-family 19,748 18,553 — 20,334 18,997 — Multifamily 354 356 — 308 310 — Total individually impaired loans with no related allowance recorded 20,102 18,909 — 20,642 19,307 — Total individually impaired loans (2) $ 136,431 $ 129,545 $ (15,921 ) $ 143,956 $ 135,781 $ (17,289 ) For the Three Months Ended June 30, 2018 2017 Average Recorded Investment Total Interest Income Recognized (3) Interest Income Recognized on a Cash Basis Average Recorded Investment Total Interest Income Recognized (3) Interest Income Recognized on a Cash Basis (Dollars in millions) Individually impaired loans: With related allowance recorded: Single-family: Primary $ 88,526 $ 915 $ 109 $ 94,599 $ 955 $ 77 Government 279 9 — 295 2 — Alt-A 19,349 219 16 24,249 240 14 Other 7,265 73 6 9,419 82 5 Total single-family 115,419 1,216 131 128,562 1,279 96 Multifamily 232 1 — 259 4 — Total individually impaired loans with related allowance recorded 115,651 1,217 131 128,821 1,283 96 With no related allowance recorded: (1) Single-family: Primary 14,942 243 32 15,091 273 24 Government 57 2 — 61 1 — Alt-A 2,723 61 5 3,026 67 2 Other 857 15 1 1,016 21 1 Total single-family 18,579 321 38 19,194 362 27 Multifamily 355 1 — 284 7 — Total individually impaired loans with no related allowance recorded 18,934 322 38 19,478 369 27 Total individually impaired loans $ 134,585 $ 1,539 $ 169 $ 148,299 $ 1,652 $ 123 For the Six Months Ended June 30, 2018 2017 Average Recorded Investment Total Interest Income Recognized (3) Interest Income Recognized on a Cash Basis Average Recorded Investment Total Interest Income Recognized (3) Interest Income Recognized on a Cash Basis (Dollars in millions) Individually impaired loans: With related allowance recorded: Single-family: Primary $ 88,342 $ 1,826 $ 216 $ 96,395 $ 1,941 $ 165 Government 278 12 — 298 5 — Alt-A 20,020 431 32 24,896 489 29 Other 7,556 144 11 9,805 169 10 Total single-family 116,196 2,413 259 131,394 2,604 204 Multifamily 248 1 — 280 6 — Total individually impaired loans with related allowance recorded 116,444 2,414 259 131,674 2,610 204 With no related allowance recorded: (1) Single-family: Primary 14,988 486 58 15,050 562 47 Government 58 2 — 61 2 — Alt-A 2,781 119 9 3,056 140 5 Other 878 31 2 1,041 44 2 Total single-family 18,705 638 69 19,208 748 54 Multifamily 340 3 — 278 10 — Total individually impaired loans with no related allowance recorded 19,045 641 69 19,486 758 54 Total individually impaired loans $ 135,489 $ 3,055 $ 328 $ 151,160 $ 3,368 $ 258 __________ (1) The discounted cash flows or collateral value equals or exceeds the carrying value of the loan and, as such, no valuation allowance is required. (2) Includes single-family loans classified as TDRs with a recorded investment of $128.5 billion and $134.7 billion as of June 30, 2018 and December 31, 2017 , respectively. Includes multifamily loans classified as TDRs with a recorded investment of $211 million and $185 million as of June 30, 2018 and December 31, 2017 , respectively. (3) Total single-family interest income recognized of $1.5 billion for the three months ended June 30, 2018 consists of $1.4 billion of contractual interest and $186 million of effective yield adjustments. Total single-family interest income recognized of $1.7 billion for the three months ended June 30, 2017 consists of $1.5 billion of contractual interest and $229 million of effective yield adjustments. Total single-family interest income recognized of $3.1 billion for the six months ended June 30, 2018 consists of $2.7 billion of contractual interest and $352 million of effective yield adjustments. Total single-family interest income recognized of $3.4 billion for the six months ended June 30, 2017 consists of $2.9 billion of contractual interest and $497 million of effective yield adjustments.
Troubled Debt Restructurings Activity [Table Text Block]	The following tables display the number of loans and recorded investment in loans classified as a TDR. For the Three Months Ended June 30, 2018 2017 Number of Loans Recorded Investment Number of Loans Recorded Investment (Dollars in millions) Single-family: Primary 21,820 $ 3,148 14,148 $ 1,945 Government 26 2 45 4 Alt-A 1,538 200 1,328 194 Other 285 52 271 46 Total single-family 23,669 3,402 15,792 2,189 Multifamily 2 19 3 17 Total TDRs 23,671 $ 3,421 15,795 $ 2,206 For the Six Months Ended June 30, 2018 2017 Number of Loans Recorded Investment Number of Loans Recorded Investment (Dollars in millions) Single-family: Primary 63,499 $ 9,672 31,383 $ 4,308 Government 74 6 106 10 Alt-A 3,720 483 2,893 418 Other 730 136 580 99 Total single-family 68,023 10,297 34,962 4,835 Multifamily 10 61 3 17 Total TDRs 68,033 $ 10,358 34,965 $ 4,852 the following tables display the number of loans and our recorded investment in these loans at the time of payment default. For purposes of this disclosure, we define loans that had a payment default as: single-family and multifamily loans with completed TDRs that liquidated during the period, either through foreclosure, deed-in-lieu of foreclosure, or a short sale; single-family loans with completed modifications that are two or more months delinquent during the period; or multifamily loans with completed modifications that are one or more months delinquent during the period. For the Three Months Ended June 30, 2018 2017 Number of Loans Recorded Investment Number of Loans Recorded Investment (Dollars in millions) Single-family: Primary 3,834 $ 554 4,238 $ 589 Government 15 2 25 3 Alt-A 588 92 616 97 Other 131 26 150 30 Total TDRs that subsequently defaulted 4,568 $ 674 5,029 $ 719 For the Six Months Ended June 30, 2018 2017 Number of Loans Recorded Investment Number of Loans Recorded Investment (Dollars in millions) Single-family: Primary 8,652 $ 1,255 8,717 $ 1,210 Government 29 4 44 5 Alt-A 1,265 201 1,230 193 Other 326 64 351 68 Total single-family 10,272 1,524 10,342 1,476 Multifamily 1 2 1 4 Total TDRs that subsequently defaulted 10,273 $ 1,526 10,343 $ 1,480
Single-family [Member]
Mortgage Loans on Real Estate [Line Items]
Credit Quality Indicators [Table Text Block]	The following table displays the total recorded investment in our single-family HFI loans by class and credit quality indicator, excluding loans for which we have elected the fair value option. As of June 30, 2018 (1) December 31, 2017 (1) Primary Alt-A Other Primary Alt-A Other (Dollars in millions) Estimated mark-to-market loan-to-value (“LTV”) ratio: (2) Less than or equal to 80% $ 2,516,133 $ 49,011 $ 14,537 $ 2,439,858 $ 51,903 $ 16,428 Greater than 80% and less than or equal to 90% 218,193 4,846 1,585 238,038 6,680 2,277 Greater than 90% and less than or equal to 100% 83,243 2,675 940 106,076 4,044 1,443 Greater than 100% 12,736 2,793 1,028 18,823 4,599 1,716 Total $ 2,830,305 $ 59,325 $ 18,090 $ 2,802,795 $ 67,226 $ 21,864 __________ (1) Excludes $24.3 billion and $31.1 billion as of June 30, 2018 and December 31, 2017 , respectively, of mortgage loans guaranteed or insured, in whole or in part, by the U.S. government or one of its agencies, that are not Alt-A loans. The segment class is primarily reverse mortgages for which we do not calculate an estimated mark-to-market LTV ratio. (2) The aggregate estimated mark-to-market LTV ratio is based on the unpaid principal balance of the loan as of the end of each reported period divided by the estimated current value of the property, which we calculate using an internal valuation model that estimates periodic changes in home value.
Multifamily [Member]
Mortgage Loans on Real Estate [Line Items]
Credit Quality Indicators [Table Text Block]	The following table displays the total recorded investment in our multifamily HFI loans by credit quality indicator, excluding loans for which we have elected the fair value option. As of June 30, December 31, 2018 2017 (Dollars in millions) Credit risk profile by internally assigned grade: Non-classified $ 273,064 $ 263,416 Classified (1) 4,403 3,585 Total $ 277,467 $ 267,001 _________ (1) Represents loans classified as “Substandard,” which have a well-defined weakness that jeopardizes the timely full repayment. Loans with a weakness that makes collection or liquidation in full highly questionable and improbable based on existing conditions and values are referred to as “Doubtful.” We had no loans classified as doubtful for the periods indicated.

Allowance for Loan Losses (Tabl

Allowance for Loan Losses (Tables)	6 Months Ended
	Jun. 30, 2018
Receivables [Abstract]
Allowance for Loan Losses Rollforward by Segment [Table Text Block]	The following table displays changes in single-family, multifamily and total allowance for loan losses. For the Three Months Ended June 30, For the Six Months Ended June 30, 2018 2017 2018 2017 (Dollars in millions) Single-family allowance for loan losses: Beginning balance $ (18,523 ) $ (21,938 ) $ (18,849 ) $ (23,283 ) Benefit for loan losses (1) 1,270 1,185 1,192 1,605 Charge-offs 731 689 1,196 1,729 Recoveries (64 ) (146 ) (124 ) (231 ) Other (2) (16 ) (8 ) (17 ) (38 ) Ending balance $ (16,602 ) $ (20,218 ) $ (16,602 ) $ (20,218 ) Multifamily allowance for loan losses: Beginning balance $ (211 ) $ (191 ) $ (235 ) $ (182 ) Benefit for loan losses (1) — 11 20 2 Charge-offs 1 — 5 — Recoveries — (1 ) — (1 ) Ending balance $ (210 ) $ (181 ) $ (210 ) $ (181 ) Total allowance for loan losses: Beginning balance $ (18,734 ) $ (22,129 ) $ (19,084 ) $ (23,465 ) Benefit for loan losses (1) 1,270 1,196 1,212 1,607 Charge-offs 732 689 1,201 1,729 Recoveries (64 ) (147 ) (124 ) (232 ) Other (2) (16 ) (8 ) (17 ) (38 ) Ending balance $ (16,812 ) $ (20,399 ) $ (16,812 ) $ (20,399 ) __________ (1) Benefit for loan losses is included in “ Benefit for credit losses ” in our condensed consolidated statements of operations and comprehensive income. (2) Amounts represent the portion of benefit for loan losses, charge-offs and recoveries that are not a part of the allowance for loan losses.
Allowance for Loan Losses and Total Recorded Investment in HFI Loans [Table Text Block]	The following table displays the carrying value of our mortgage loans. As of June 30, 2018 December 31, 2017 (Dollars in millions) Single-family $ 2,910,803 $ 2,890,634 Multifamily 275,797 265,069 Total unpaid principal balance of mortgage loans 3,186,600 3,155,703 Cost basis and fair value adjustments, net 38,836 41,906 Allowance for loan losses for loans held for investment (16,812 ) (19,084 ) Total mortgage loans $ 3,208,624 $ 3,178,525 The following table displays information about our redesignated mortgage loans. For the Three Months Ended June 30, For the Six Months Ended June 30, 2018 2017 2018 2017 (Dollars in millions) Carrying value of loans redesignated from HFI to HFS $ 6,235 $ 2,879 $ 13,602 $ 5,422 Carrying value of loans redesignated from HFS to HFI 12 17 30 52 Loans sold - unpaid principal balance 3,710 2,947 4,458 3,040 Realized gains on sale of mortgage loans 210 55 208 53 The following table displays the allowance for loan losses and recorded investment in our HFI loans by impairment or allowance methodology and portfolio segment, excluding loans for which we have elected the fair value option. As of June 30, 2018 December 31, 2017 Single-Family Multifamily Total Single-Family Multifamily Total (Dollars in millions) Allowance for loan losses by segment: Individually impaired loans (1) $ (15,882 ) $ (39 ) $ (15,921 ) $ (17,247 ) $ (42 ) $ (17,289 ) Collectively reserved loans (720 ) (171 ) (891 ) (1,602 ) (193 ) (1,795 ) Total allowance for loan losses $ (16,602 ) $ (210 ) $ (16,812 ) $ (18,849 ) $ (235 ) $ (19,084 ) Recorded investment in loans by segment: Individually impaired loans (1) $ 128,959 $ 586 $ 129,545 $ 135,191 $ 590 $ 135,781 Collectively reserved loans 2,803,080 276,881 3,079,961 2,787,783 266,411 3,054,194 Total recorded investment in loans $ 2,932,039 $ 277,467 $ 3,209,506 $ 2,922,974 $ 267,001 $ 3,189,975 __________ (1) Includes acquired credit-impaired loans.

Investments in Securities (Tabl

Investments in Securities (Tables)	6 Months Ended
	Jun. 30, 2018
Investments, Debt and Equity Securities [Abstract]
Investments In Trading Securities [Table Text Block]	The following table displays our investments in trading securities. As of June 30, 2018 December 31, 2017 (Dollars in millions) Mortgage-related securities: Fannie Mae (1) $ 1,696 $ 3,876 Other agency 3,494 1,118 Alt-A and subprime private-label securities (1) 1,430 453 Commercial mortgage-backed securities (“CMBS”) — 9 Mortgage revenue bonds 1 1 Total mortgage-related securities 6,621 5,457 Non-mortgage-related securities: U.S. Treasury securities 35,663 29,222 Other securities 97 — Total non-mortgage-related securities 35,760 29,222 Total trading securities $ 42,381 $ 34,679 __________ (1) The increase in Alt-A and subprime private-label securities and the corresponding decrease in Fannie Mae securities from December 31, 2017 to June 30, 2018 was due to the dissolution of a Fannie Mae-wrapped private-label securities trust in the first quarter of 2018.
Schedule of Trading Securities Gains (Losses), Net [Table Text Block]	The following table displays information about our net trading gains (losses). For the Three Months Ended June 30, For the Six Months Ended June 30, 2018 2017 2018 2017 (Dollars in millions) Net trading gains $ 21 $ 18 $ 119 $ 86 Net trading gains (losses) recognized in the period related to securities still held at period end 1 (7 ) 48 71
Schedule of Realized Gain (Loss) [Table Text Block]	The following table displays the gross realized gains and proceeds on sales of AFS securities. For the Three Months For the Six Months Ended June 30, Ended June 30, 2018 2017 2018 2017 (Dollars in millions) Gross realized gains $ — $ 227 $ 363 $ 230 Total proceeds (excludes initial sale of securities from new portfolio securitizations) 6 799 641 894
Schedule of Available-for-sale Securities Reconciliation [Table Text Block]	The following tables display the amortized cost, gross unrealized gains and losses, and fair value by major security type for AFS securities. As of June 30, 2018 Total Amortized Cost (1) Gross Unrealized Gains Gross Unrealized Losses (2) Total Fair Value (Dollars in millions) Fannie Mae $ 1,866 $ 72 $ (34 ) $ 1,904 Other agency 279 19 — 298 Alt-A and subprime private-label securities 357 292 — 649 Mortgage revenue bonds 494 16 (4 ) 506 Other mortgage-related securities 342 24 — 366 Total $ 3,338 $ 423 $ (38 ) $ 3,723 As of December 31, 2017 Total Amortized Cost (1) Gross Unrealized Gains Gross Unrealized Losses (2) Total Fair Value (Dollars in millions) Fannie Mae $ 2,044 $ 102 $ (27 ) $ 2,119 Other agency 332 25 — 357 Alt-A and subprime private-label securities 662 652 — 1,314 CMBS 15 — — 15 Mortgage revenue bonds 655 20 (4 ) 671 Other mortgage-related securities 350 17 — 367 Total $ 4,058 $ 816 $ (31 ) $ 4,843 __________ (1) Amortized cost consists of unpaid principal balance, unamortized premiums, discounts and other cost basis adjustments, as well as net other-than-temporary impairments (“OTTI”) recognized in “ Investment gains, net ” in our condensed consolidated statements of operations and comprehensive income. (2) Represents the gross unrealized losses on securities for which we have not recognized OTTI, as well as the noncredit component of OTTI and cumulative changes in fair value of securities for which we previously recognized the credit component of OTTI in “ Accumulated other comprehensive income ” in our condensed consolidated balance sheets.
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Table Text Block]	The following tables display additional information regarding gross unrealized losses and fair value by major security type for AFS securities in an unrealized loss position. As of June 30, 2018 Less Than 12 Consecutive Months 12 Consecutive Months or Longer Gross Unrealized Losses Fair Value Gross Unrealized Losses Fair Value (Dollars in millions) Fannie Mae $ (5 ) $ 190 $ (29 ) $ 419 Mortgage revenue bonds (1 ) 29 (3 ) 3 Total $ (6 ) $ 219 $ (32 ) $ 422 As of December 31, 2017 Less Than 12 Consecutive Months 12 Consecutive Months or Longer Gross Unrealized Losses Fair Value Gross Unrealized Losses Fair Value (Dollars in millions) Fannie Mae $ (1 ) $ 134 $ (26 ) $ 461 Mortgage revenue bonds — — (4 ) 3 Total $ (1 ) $ 134 $ (30 ) $ 464
Investments Classified by Contractual Maturity Date [Table Text Block]	The following table displays the amortized cost and fair value of our AFS securities by major security type and remaining contractual maturity, assuming no principal prepayments. The contractual maturity of mortgage-backed securities is not a reliable indicator of their expected life because borrowers generally have the right to prepay their obligations at any time. As of June 30, 2018 Total Amortized Cost Total Fair Value One Year or Less After One Year Through Five Years After Five Years Through Ten Years After Ten Years Amortized Cost Fair Value Amortized Cost Fair Value Amortized Cost Fair Value Amortized Cost Fair Value (Dollars in millions) Fannie Mae $ 1,866 $ 1,904 $ — $ — $ 12 $ 12 $ 80 $ 85 $ 1,774 $ 1,807 Other agency 279 298 2 2 11 11 44 47 222 238 Alt-A and subprime private-label securities 357 649 — — — — — — 357 649 Mortgage revenue bonds 494 506 4 4 33 33 61 61 396 408 Other mortgage-related securities 342 366 — — — — 6 6 336 360 Total $ 3,338 $ 3,723 $ 6 $ 6 $ 56 $ 56 $ 191 $ 199 $ 3,085 $ 3,462

Financial Guarantees (Tables)

Financial Guarantees (Tables)	6 Months Ended
	Jun. 30, 2018
Guarantees [Abstract]
Financial Guarantees and Maximum Recovery [Table Text Block]	The following table displays our maximum exposure, guaranty obligation recognized in our condensed consolidated balance sheets, and the maximum potential recovery from third parties through available credit enhancements and recourse related to our financial guarantees. As of June 30, 2018 December 31, 2017 Maximum Exposure Guaranty Obligation Maximum Recovery (1) Maximum Exposure Guaranty Obligation Maximum Recovery (1) (Dollars in millions) Unconsolidated Fannie Mae MBS $ 7,680 $ 30 $ 7,054 $ 10,876 $ 127 $ 7,340 Other guaranty arrangements (2) 13,824 133 2,320 14,265 131 2,404 Total $ 21,504 $ 163 $ 9,374 $ 25,141 $ 258 $ 9,744 __________ (1) Recoverability of such credit enhancements and recourse is subject to, among other factors, our mortgage insurers’ and financial guarantors’ ability to meet their obligations to us. For information on our mortgage insurers and financial guarantors, see “Note 13, Concentrations of Credit Risk” in our 2017 Form 10-K and “ Note 11, Concentrations of Credit Risk ” in this report. (2) Primarily consists of credit enhancements and long-term standby commitments.

Short-Term and Long-Term Debt (

Short-Term and Long-Term Debt (Tables)	6 Months Ended
	Jun. 30, 2018
Debt Disclosure [Abstract]
Short-Term Debt [Table Text Block]	The following table displays our outstanding short-term debt (debt with an original contractual maturity of one year or less) and weighted-average interest rates of this debt. As of June 30, 2018 December 31, 2017 Outstanding Weighted- Average Interest Rate (1) Outstanding Weighted- Average Interest Rate (1) (Dollars in millions) Short-term debt of Fannie Mae $ 25,726 1.86 % $ 33,377 1.18 % Debt of consolidated trusts 339 1.88 379 1.11 Total short-term debt $ 26,065 1.86 % $ 33,756 1.18 % __________ (1) Includes the effects of discounts, premiums and other cost basis adjustments.
Long-Term Debt [Table Text Block]	The following table displays our outstanding long-term debt. As of June 30, 2018 December 31, 2017 Maturities Outstanding Weighted- Average Interest Rate (1) Maturities Outstanding Weighted- Average Interest Rate (1) (Dollars in millions) Senior fixed: Benchmark notes and bonds 2018 - 2030 $ 116,563 2.28 % 2018 - 2030 $ 123,541 2.11 % Medium-term notes (2) 2018 - 2026 69,986 1.46 2018 - 2026 75,901 1.41 Other (3) 2018 - 2038 6,876 4.66 2018 - 2038 7,421 4.84 Total senior fixed 193,425 2.06 206,863 1.95 Senior floating: Medium-term notes (2) 2019 - 2020 1,175 1.86 2018 - 2020 8,425 1.36 Connecticut Avenue Securities (4) 2023 - 2030 24,589 5.66 2023 - 2030 22,527 5.18 Other (5) 2020 - 2037 354 9.00 2020 - 2037 376 6.36 Total senior floating 26,118 5.54 31,328 4.14 Subordinated debentures 2019 5,357 9.96 2019 5,106 9.93 Secured borrowings (6) 2021 - 2022 64 1.66 2021 - 2022 78 1.70 Total long-term debt of Fannie Mae (7) 224,964 2.66 243,375 2.40 Debt of consolidated trusts 2018 - 2057 3,086,460 2.84 2018 - 2057 3,052,923 2.80 Total long-term debt $ 3,311,424 2.83 % $ 3,296,298 2.77 % __________ (1) Includes the effects of discounts, premiums and other cost basis adjustments. (2) Includes long-term debt with an original contractual maturity of greater than 1 year and up to 10 years, excluding zero-coupon debt. (3) Includes other long-term debt with an original contractual maturity of greater than 10 years and foreign exchange bonds. (4) Credit risk-sharing securities that transfer a portion of the credit risk on specified pools of single-family mortgage loans to the investors in these securities, a portion of which is reported at fair value. (5) Consists of structured debt instruments that are reported at fair value. (6) Represents our remaining liability resulting from the transfer of financial assets from our condensed consolidated balance sheets that did not qualify as a sale under the accounting guidance for the transfer of financial instruments. (7) Includes unamortized discounts and premiums, other cost basis adjustments and fair value adjustments of $517 million and $752 million as of June 30, 2018 and December 31, 2017 , respectively.

Derivative Instruments (Tables)

Derivative Instruments (Tables)	6 Months Ended
	Jun. 30, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Notional and Fair Value Position [Table Text Block]	The following table displays the notional amount and estimated fair value of our asset and liability derivative instruments. As of June 30, 2018 As of December 31, 2017 Asset Derivatives Liability Derivatives Asset Derivatives Liability Derivatives Notional Amount Estimated Fair Value Notional Amount Estimated Fair Value Notional Amount Estimated Fair Value Notional Amount Estimated Fair Value (Dollars in millions) Risk management derivatives: Swaps: Pay-fixed $ 93,391 $ 723 $ 19,845 $ (674 ) $ 52,732 $ 772 $ 70,211 $ (2,120 ) Receive-fixed 106,673 1,123 63,209 (1,296 ) 31,671 2,391 138,852 (1,764 ) Basis 273 98 600 — 873 124 — — Foreign currency 229 37 231 (59 ) 234 59 236 (56 ) Swaptions: Pay-fixed 11,525 254 600 (2 ) 9,750 95 4,000 (20 ) Receive-fixed 500 19 7,375 (336 ) 250 13 9,250 (304 ) Other (1) 24,716 20 — (1 ) 13,240 22 7,315 (1 ) Total gross risk management derivatives 237,307 2,274 91,860 (2,368 ) 108,750 3,476 229,864 (4,265 ) Accrued interest receivable (payable) — 418 — (438 ) — 835 — (814 ) Netting adjustment (2) — (2,608 ) — 2,756 — (4,272 ) — 4,979 Total net risk management derivatives $ 237,307 $ 84 $ 91,860 $ (50 ) $ 108,750 $ 39 $ 229,864 $ (100 ) Mortgage commitment derivatives: Mortgage commitments to purchase whole loans $ 6,025 $ 20 $ 1,506 $ (1 ) $ 4,143 $ 9 $ 1,570 $ (2 ) Forward contracts to purchase mortgage-related securities 80,636 263 11,060 (16 ) 45,925 108 21,099 (21 ) Forward contracts to sell mortgage-related securities 5,498 5 134,031 (537 ) 19,320 15 85,556 (205 ) Total mortgage commitment derivatives 92,159 288 146,597 (554 ) 69,388 132 108,225 (228 ) Derivatives at fair value $ 329,466 $ 372 $ 238,457 $ (604 ) $ 178,138 $ 171 $ 338,089 $ (328 ) __________ (1) Includes credit risk transfer transactions, futures, swap credit enhancements and mortgage insurance contracts that we account for as derivatives. (2) The netting adjustment represents the effect of the legal right to offset under legally enforceable master netting arrangements to settle with the same counterparty on a net basis, including cash collateral posted and received. Cash collateral posted was $742 million and $1.4 billion as of June 30, 2018 and December 31, 2017 , respectively. Cash collateral received was $594 million and $649 million as of June 30, 2018 and December 31, 2017 , respectively.
Fair Value Gain (Loss), Net [Table Text Block]	The following table displays, by type of derivative instrument, the fair value gains and losses, net on our derivatives. For the Three Months For the Six Months Ended June 30, Ended June 30, 2018 2017 2018 2017 (Dollars in millions) Risk management derivatives: Swaps: Pay-fixed $ 967 $ (691 ) $ 3,750 $ — Receive-fixed (597 ) 639 (2,984 ) 322 Basis (3 ) 16 (26 ) 23 Foreign currency (41 ) 11 (25 ) 23 Swaptions: Pay-fixed 36 (48 ) 165 (48 ) Receive-fixed (22 ) (8 ) (38 ) (26 ) Other (16 ) 3 (4 ) (5 ) Net accrual of periodic settlements (286 ) (224 ) (501 ) (479 ) Total risk management derivatives fair value gains (losses), net 38 (302 ) 337 (190 ) Mortgage commitment derivatives fair value gains (losses), net (76 ) (192 ) 488 (272 ) Total derivatives fair value gains (losses), net $ (38 ) $ (494 ) $ 825 $ (462 )

Segment Reporting (Tables)

Segment Reporting (Tables)	6 Months Ended
	Jun. 30, 2018
Segment Reporting [Abstract]
Segment results [Table Text Block]	The following table displays our segment results. For the Three Months Ended June 30, 2018 2017 Single-Family Multifamily Total Single-Family Multifamily Total (Dollars in millions) Net interest income (1) $ 4,723 $ 654 $ 5,377 $ 4,366 $ 636 $ 5,002 Fee and other income (2) 69 170 239 111 242 353 Net revenues 4,792 824 5,616 4,477 878 5,355 Investment gains, net (3) 252 25 277 321 64 385 Fair value gains (losses), net (4) 278 (49 ) 229 (685 ) (6 ) (691 ) Administrative expenses (649 ) (106 ) (755 ) (600 ) (86 ) (686 ) Credit-related income (expense) (5) Benefit for credit losses 1,295 1 1,296 1,255 12 1,267 Foreclosed property expense (136 ) (3 ) (139 ) (32 ) (2 ) (34 ) Total credit-related income (expense) 1,159 (2 ) 1,157 1,223 10 1,233 TCCA fees (6) (565 ) — (565 ) (518 ) — (518 ) Other expenses, net (270 ) (96 ) (366 ) (155 ) (136 ) (291 ) Income before federal income taxes 4,997 596 5,593 4,063 724 4,787 Provision for federal income taxes (1,044 ) (92 ) (1,136 ) (1,401 ) (186 ) (1,587 ) Net income $ 3,953 $ 504 $ 4,457 $ 2,662 $ 538 $ 3,200 For the Six Months Ended June 30, 2018 2017 Single-Family Multifamily Total Single-Family Multifamily Total (Dollars in millions) Net interest income (1) $ 9,284 $ 1,325 $ 10,609 $ 9,122 $ 1,226 $ 10,348 Fee and other income (2) 227 332 559 187 415 602 Net revenues 9,511 1,657 11,168 9,309 1,641 10,950 Investment gains, net (3) 494 33 527 271 105 376 Fair value gains (losses), net (4) 1,312 (38 ) 1,274 (697 ) (34 ) (731 ) Administrative expenses (1,292 ) (213 ) (1,505 ) (1,201 ) (169 ) (1,370 ) Credit-related income (expense) (5) Benefit for credit losses 1,491 22 1,513 1,655 8 1,663 Foreclosed property expense (298 ) (3 ) (301 ) (248 ) (3 ) (251 ) Total credit-related income 1,193 19 1,212 1,407 5 1,412 TCCA fees (6) (1,122 ) — (1,122 ) (1,021 ) — (1,021 ) Other expenses, net (402 ) (167 ) (569 ) (411 ) (262 ) (673 ) Income before federal income taxes 9,694 1,291 10,985 7,657 1,286 8,943 Provision for federal income taxes (2,060 ) (207 ) (2,267 ) (2,653 ) (317 ) (2,970 ) Net income $ 7,634 $ 1,084 $ 8,718 $ 5,004 $ 969 $ 5,973 __________ (1) Net interest income primarily consists of guaranty fees received as compensation for assuming and managing the credit risk on loans underlying Fannie Mae MBS held by third parties for the respective business segment, and the difference between the interest income earned on the respective business segment’s mortgage assets in our retained mortgage portfolio and the interest expense associated with the debt funding those assets. Revenues from single-family guaranty fees include revenues generated by the 10 basis point increase in guaranty fees pursuant to TCCA. (2) Single-Family fee and other income primarily consists of compensation for engaging in structured transactions and providing other lender services, and income resulting from settlement agreements resolving certain claims relating to private-label securities we purchased or that we have guaranteed. Multifamily fee and other income consists of fees associated with multifamily business activities, including yield maintenance income. (3) Investment gains and losses primarily consists of gains and losses on the sale of mortgage assets for the respective business segment. (4) Single-Family fair value gains and losses primarily consist of fair value gains and losses on risk management and mortgage commitment derivatives, trading securities and other financial instruments associated with our single-family total book of business. Multifamily fair value gains and losses primarily consist of fair value gains and losses on MBS commitment derivatives, trading securities and other financial instruments associated with our multifamily total book of business. (5) Credit-related income or expense is based on the guaranty book of business of the respective business segment and consists of the applicable segment’s benefit or provision for credit losses and foreclosed property expense on loans underlying the segment’s guaranty book of business. (6) Consists of the portion of our single-family guaranty fees that is remitted to Treasury pursuant to the TCCA.

Equity (Tables)

Equity (Tables)	6 Months Ended
	Jun. 30, 2018
Equity [Abstract]
Schedule of Other Comprehensive Income (Loss) [Table Text Block]	The following table displays the activity in other comprehensive income (loss) , net of tax, by major categories. For the Three Months Ended June 30, For the Six Months Ended June 30, 2018 2017 2018 2017 (Dollars in millions) Net income $ 4,457 $ 3,200 $ 8,718 $ 5,973 Other comprehensive income (loss), net of tax effect: Changes in net unrealized gains (losses) on AFS securities (net of tax of $1 and $6, respectively, for the three months ended and net of tax of $14 and $11, respectively, for the six months ended) 4 11 (53 ) 20 Reclassification adjustments for gains on AFS securities and other-than-temporary impairment (“OTTI”) recognized in net income (net of tax of $0 and $50, respectively, for the three months ended and $70 and $51, respectively, for the six months ended) — (92 ) (263 ) (93 ) Other (2 ) (2 ) (5 ) (4 ) Total other comprehensive income (loss) 2 (83 ) (321 ) (77 ) Total comprehensive income $ 4,459 $ 3,117 $ 8,397 $ 5,896
Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block]	The following table displays our accumulated other comprehensive income , net of tax, by major categories. As of June 30, December 31, 2018 2017 (Dollars in millions) Net unrealized gains on AFS securities for which we have not recorded OTTI $ 50 $ 87 Net unrealized gains on AFS securities for which we have recorded OTTI 254 423 Other 45 43 Accumulated other comprehensive income $ 349 $ 553 The following table displays changes in accumulated other comprehensive income , net of tax. For the Three Months Ended June 30, For the Six Months Ended June 30, 2018 2017 2018 2017 AFS (1) Other Total AFS (1) Other Total AFS (1) Other Total AFS (1) Other Total (Dollars in millions) Beginning balance $ 300 $ 47 $ 347 $ 724 $ 41 $ 765 $ 510 $ 43 $ 553 $ 716 $ 43 $ 759 Reclassification of accumulated other comprehensive income to retained earnings resulting from the enactment of the Tax Cuts and Jobs Act (2) — — — — — — 110 7 117 — — — Other comprehensive income (loss) before reclassifications 4 — 4 11 — 11 (53 ) — (53 ) 20 — 20 Amounts reclassified from other comprehensive income (loss) — (2 ) (2 ) (92 ) (2 ) (94 ) (263 ) (5 ) (268 ) (93 ) (4 ) (97 ) Net other comprehensive income (loss) 4 (2 ) 2 (81 ) (2 ) (83 ) (316 ) (5 ) (321 ) (73 ) (4 ) (77 ) Ending balance $ 304 $ 45 $ 349 $ 643 $ 39 $ 682 $ 304 $ 45 $ 349 $ 643 $ 39 $ 682 __________ (1) The amounts reclassified from accumulated other comprehensive income represent the gain or loss recognized in earnings due to a sale of an AFS security or the recognition of a net impairment recognized in earnings, which are recorded in “ Investment gains, net ” in our condensed consolidated statements of operations and comprehensive income. (2) Reclassification from accumulated other comprehensive income to retained earnings of the tax effects resulting from the enactment of tax legislation on December 22, 2017 that reduced the federal corporate income tax rate from 35% to 21% effective January 1, 2018 . This amount is not included in Net other comprehensive income (loss) for the period ending June 30, 2018 .

Concentrations of Credit Risk (

Concentrations of Credit Risk (Tables)	6 Months Ended
	Jun. 30, 2018
Single-family [Member]
Concentration Risk [Line Items]
Schedule of Delinquency Status Guaranty Book of Business [Table Text Block]	The following tables display the delinquency status and serious delinquency rates for specified loan categories of our single-family conventional and total multifamily guaranty book of business. As of June 30, 2018 (1) December 31, 2017 (1) 30 Days Delinquent 60 Days Delinquent Seriously Delinquent (2) 30 Days Delinquent 60 Days Delinquent Seriously Delinquent (2) Percentage of single-family conventional guaranty book of business (3) 1.14 % 0.29 % 0.90 % 1.42 % 0.43 % 1.15 % Percentage of single-family conventional loans (4) 1.34 0.34 0.97 1.63 0.50 1.24
Schedule of Risk Characteristics Guaranty Book of Business [Table Text Block]	As of June 30, 2018 (1) December 31, 2017 (1) Percentage of Single-Family Conventional Guaranty Book of Business (3) Seriously Delinquent Rate (2) Percentage of Single-Family Conventional Guaranty Book of Business (3) Seriously Delinquent Rate (2) Estimated mark-to-market loan-to-value ratio: Greater than 100% 1 % 11.41 % 1 % 11.70 % Geographical distribution: California 19 0.36 19 0.42 Florida 6 2.51 6 3.71 New Jersey 4 1.68 4 2.15 New York 5 1.66 5 2.02 All other states 66 0.88 66 1.09 Product distribution: Alt-A 2 4.21 2 4.95 Vintages: 2004 and prior 3 3.00 4 3.28 2005-2008 6 5.54 6 6.55 2009-2018 91 0.41 90 0.53 __________ (1) Consists of the portion of our single-family conventional guaranty book of business for which we have detailed loan level information, which constituted approximately 99% of our total single-family conventional guaranty book of business as of June 30, 2018 and December 31, 2017 . (2) Consists of single-family conventional loans that were 90 days or more past due or in the foreclosure process as of June 30, 2018 and December 31, 2017 . (3) Calculated based on the aggregate unpaid principal balance of single-family conventional loans for each category divided by the aggregate unpaid principal balance of loans in our single-family conventional guaranty book of business. (4) Calculated based on the number of single-family conventional loans that were delinquent divided by the total number of loans in our single-family conventional guaranty book of business.
Schedule of Risk in Force Mortgage Insurance Coverage [Table Text Block]	The following table displays our total mortgage insurance risk in force by primary and pool insurance, as well as the total risk in force mortgage insurance coverage as a percentage of the single-family guaranty book of business. As of June 30, 2018 December 31, 2017 Risk in Force Percentage of Single-Family Guaranty Book of Business Risk in Force Percentage of Single-Family Guaranty Book of Business (Dollars in millions) Mortgage insurance risk in force: Primary mortgage insurance $ 144,023 $ 137,941 Pool mortgage insurance 432 519 Total mortgage insurance risk in force $ 144,455 5% $ 138,460 5%
Schedule of Risk in Force Mortgage Insurance Coverage, by Counterparty [Table Text Block]	The table below displays our mortgage insurer counterparties that provided approximately 10% or more of the risk in force mortgage insurance coverage on the single-family loans in our guaranty book of business. Percentage of Total Risk in Force Mortgage Insurance Coverage As of June 30, 2018 December 31, 2017 Counterparty: (1) Arch Capital Group Ltd. (2) 25 % 25 % Radian Guaranty, Inc. 21 21 Mortgage Guaranty Insurance Corp. 19 19 Genworth Mortgage Insurance Corp. 15 15 Essent Guaranty, Inc. 11 11 Others 9 9 Total 100 % 100 % __________ (1) Insurance coverage amounts provided for each counterparty may include coverage provided by affiliates and subsidiaries of the counterparty. (2) Arch Capital Group Ltd. is the parent company of Arch Mortgage Insurance Co. and United Guaranty Residential Insurance Co.
Schedules of Concentration of Risk, by Risk Factor [Table Text Block]	The table below displays the percentage of our single-family guaranty book of business serviced by our top five depository single-family mortgage servicers and top five non-depository single-family mortgage servicers, and identifies one servicer that serviced more than 10% of our single-family guaranty book of business. Percentage of Single-Family Guaranty Book of Business As of June 30, 2018 December 31, 2017 Wells Fargo Bank, N.A. (together with its affiliates) 18 % 18 % Remaining top five depository servicers 16 17 Top five non-depository servicers 21 20 Total 55 % 55 %
Multifamily [Member]
Concentration Risk [Line Items]
Schedule of Delinquency Status Guaranty Book of Business [Table Text Block]	As of June 30, 2018 (1)(2) December 31, 2017 (1)(2) 30 Days Delinquent Seriously Delinquent (3) 30 Days Delinquent Seriously Delinquent (3) Percentage of multifamily guaranty book of business 0.01 % 0.10 % 0.03 % 0.11 %
Schedule of Risk Characteristics Guaranty Book of Business [Table Text Block]	As of June 30, 2018 December 31, 2017 Percentage of Multifamily Guaranty Book of Business (2) Percentage Seriously Delinquent (3)(4) Percentage of Multifamily Guaranty Book of Business (2) Percentage Seriously Delinquent (3)(4) Original LTV ratio: Greater than 80% 1 % 0.19 % 2 % 0.21 % Less than or equal to 80% 99 0.10 98 0.11 Current DSCR less than 1.0 (5) 2 3.25 2 1.96 __________ (1) Consists of the portion of our multifamily guaranty book of business for which we have detailed loan level information, which constituted approximately 99% of our total multifamily guaranty book of business as of June 30, 2018 and December 31, 2017 , excluding loans that have been defeased. (2) Calculated based on the aggregate unpaid principal balance of multifamily loans for each category divided by the aggregate unpaid principal balance of loans in our multifamily guaranty book of business. (3) Consists of multifamily loans that were 60 days or more past due as of the dates indicated. (4) Calculated based on the unpaid principal balance of multifamily loans that were seriously delinquent divided by the aggregate unpaid principal balance of multifamily loans for each category included in our guaranty book of business. (5) Our estimates of current DSCRs are based on the latest available income information for these properties. Although we use the most recently available results of our multifamily borrowers, there is a lag in reporting, which typically can range from 3 to 6 months but in some cases may be longer.
Schedules of Concentration of Risk, by Risk Factor [Table Text Block]	The table below displays the percentage of our multifamily guaranty book of business serviced by our top five multifamily mortgage servicers, and identifies two servicers that serviced 10% or more of our multifamily guaranty book of business. Percentage of Multifamily Guaranty Book of Business As of June 30, 2018 December 31, 2017 Wells Fargo Bank, N.A. (together with its affiliates) 14 % 14 % Walker & Dunlop, LLC 11 12 Remaining top five servicers 23 22 Total 48 % 48 %

Netting Arrangements (Tables)

Netting Arrangements (Tables)	6 Months Ended
	Jun. 30, 2018
Offsetting [Abstract]
Offsetting [Table Text Block]	The tables below display information related to derivatives, securities purchased under agreements to resell or similar arrangements, and securities sold under agreements to repurchase or similar arrangements, which are subject to an enforceable master netting arrangement or similar agreement that are either offset or not offset in our condensed consolidated balance sheets. As of June 30, 2018 Gross Amount Offset (1) Net Amount Presented in our Condensed Consolidated Balance Sheets Amounts Not Offset in our Condensed Consolidated Balance Sheets Gross Amount Financial Instruments (2) Collateral (3) Net Amount (Dollars in millions) Assets: OTC risk management derivatives $ 2,672 $ (2,630 ) $ 42 $ — $ — $ 42 Cleared risk management derivatives — 22 22 — — 22 Mortgage commitment derivatives 288 — 288 (196 ) — 92 Total derivative assets 2,960 (2,608 ) 352 (4) (196 ) — 156 Securities purchased under agreements to resell or similar arrangements (5) 27,350 — 27,350 — (27,350 ) — Total assets $ 30,310 $ (2,608 ) $ 27,702 $ (196 ) $ (27,350 ) $ 156 Liabilities: OTC risk management derivatives $ (2,805 ) $ 2,757 $ (48 ) $ — $ — $ (48 ) Cleared risk management derivatives — (1 ) (1 ) — 1 — Mortgage commitment derivatives (554 ) — (554 ) 196 325 (33 ) Total derivative liabilities (3,359 ) 2,756 (603 ) (4) 196 326 (81 ) Total liabilities $ (3,359 ) $ 2,756 $ (603 ) $ 196 $ 326 $ (81 ) As of December 31, 2017 Gross Amount Offset (1) Net Amount Presented in our Condensed Consolidated Balance Sheets Amounts Not Offset in our Condensed Consolidated Balance Sheets Gross Amount Financial Instruments (2) Collateral (3) Net Amount (Dollars in millions) Assets: OTC risk management derivatives $ 2,479 $ (2,464 ) $ 15 $ — $ — $ 15 Cleared risk management derivatives 1,811 (1,808 ) 3 — — 3 Mortgage commitment derivatives 132 — 132 (117 ) (1 ) 14 Total derivative assets 4,422 (4,272 ) 150 (4) (117 ) (1 ) 32 Securities purchased under agreements to resell or similar arrangements (5) 44,670 — 44,670 — (44,670 ) — Total assets $ 49,092 $ (4,272 ) $ 44,820 $ (117 ) $ (44,671 ) $ 32 Liabilities: OTC risk management derivatives $ (3,045 ) $ 2,957 $ (88 ) $ — $ — $ (88 ) Cleared risk management derivatives (2,033 ) 2,022 (11 ) — 11 — Mortgage commitment derivatives (228 ) — (228 ) 117 93 (18 ) Total derivative liabilities (5,306 ) 4,979 (327 ) (4) 117 104 (106 ) Total liabilities $ (5,306 ) $ 4,979 $ (327 ) $ 117 $ 104 $ (106 ) __________ (1) Represents the effect of the right to offset under legally enforceable master netting arrangements to settle with the same counterparty on a net basis, including cash collateral posted and received and accrued interest. (2) Mortgage commitment derivative amounts reflect where we have recognized both an asset and a liability with the same counterparty under an enforceable master netting arrangement but we have not elected to offset the related amounts in our condensed consolidated balance sheets. (3) Represents collateral received or posted that has not been offset in our condensed consolidated balance sheets. Does not include collateral held or posted in excess of our exposure. The fair value of non-cash collateral we pledged was $2.2 billion and $747 million as of June 30, 2018 and December 31, 2017 , respectively, which the counterparty was permitted to sell or repledge. The fair value of non-cash collateral received was $27.4 billion and $44.7 billion , of which $24.9 billion and $42.5 billion could be sold or repledged as of June 30, 2018 and December 31, 2017 , respectively. None of the underlying collateral was sold or repledged as of June 30, 2018 or December 31, 2017 . (4) Excludes derivative assets of $20 million and $21 million as of June 30, 2018 and December 31, 2017 , respectively, and derivative liabilities of $1 million as of June 30, 2018 and December 31, 2017 , recognized in our condensed consolidated balance sheets that are not subject to enforceable master netting arrangements. (5) Includes $11.1 billion and $25.2 billion in securities purchased under agreements to resell classified as “Cash and cash equivalents” in our condensed consolidated balance sheets as of June 30, 2018 and December 31, 2017 .

Fair Value (Tables)

Fair Value (Tables)	6 Months Ended
	Jun. 30, 2018
Fair Value Disclosures [Abstract]
Recurring Changes in Fair Value [Table Text Block]	The following tables display our assets and liabilities measured in our condensed consolidated balance sheets at fair value on a recurring basis subsequent to initial recognition, including instruments for which we have elected the fair value option. Fair Value Measurements as of June 30, 2018 Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Netting Adjustment (1) Estimated Fair Value (Dollars in millions) Recurring fair value measurements: Assets: Cash equivalents (2) $ 498 $ — $ — $ — $ 498 Trading securities: Mortgage-related securities: Fannie Mae — 1,617 79 — 1,696 Other agency — 3,494 — — 3,494 Alt-A and subprime private-label securities — 1,430 — — 1,430 Mortgage revenue bonds — — 1 — 1 Non-mortgage-related securities: U.S. Treasury securities 35,663 — — — 35,663 Other securities — 97 — — 97 Total trading securities 35,663 6,638 80 — 42,381 Available-for-sale securities: Mortgage-related securities: Fannie Mae — 1,700 204 — 1,904 Other agency — 298 — — 298 Alt-A and subprime private-label securities — 623 26 — 649 Mortgage revenue bonds — — 506 — 506 Other — 9 357 — 366 Total available-for-sale securities — 2,630 1,093 — 3,723 Mortgage loans — 8,610 1,018 — 9,628 Other assets: Risk management derivatives: Swaps — 2,291 108 — 2,399 Swaptions — 273 — — 273 Other — — 20 — 20 Netting adjustment — — — (2,608 ) (2,608 ) Mortgage commitment derivatives — 287 1 — 288 Total other assets — 2,851 129 (2,608 ) 372 Total assets at fair value $ 36,161 $ 20,729 $ 2,320 $ (2,608 ) $ 56,602 Fair Value Measurements as of June 30, 2018 Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Netting Adjustment (1) Estimated Fair Value (Dollars in millions) Liabilities: Long-term debt: Of Fannie Mae: Senior floating $ — $ 7,204 $ 354 $ — $ 7,558 Total of Fannie Mae — 7,204 354 — 7,558 Of consolidated trusts — 26,356 319 — 26,675 Total long-term debt — 33,560 673 — 34,233 Other liabilities: Risk management derivatives: Swaps — 2,466 1 — 2,467 Swaptions — 338 — — 338 Other — — 1 — 1 Netting adjustment — — — (2,756 ) (2,756 ) Mortgage commitment derivatives — 544 10 — 554 Total other liabilities — 3,348 12 (2,756 ) 604 Total liabilities at fair value $ — $ 36,908 $ 685 $ (2,756 ) $ 34,837 Fair Value Measurements as of December 31, 2017 Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Netting Adjustment (1) Estimated Fair Value (Dollars in millions) Recurring fair value measurements: Assets: Trading securities: Mortgage-related securities: Fannie Mae $ — $ 2,905 $ 971 $ — $ 3,876 Other agency — 1,083 35 — 1,118 Alt-A and subprime private-label securities — 259 194 — 453 CMBS — 9 — — 9 Mortgage revenue bonds — — 1 — 1 Non-mortgage-related securities: U.S. Treasury securities 29,222 — — — 29,222 Total trading securities 29,222 4,256 1,201 — 34,679 Available-for-sale securities: Mortgage-related securities: Fannie Mae — 1,911 208 — 2,119 Other agency — 357 — — 357 Alt-A and subprime private-label securities — 1,237 77 — 1,314 CMBS — 15 — — 15 Mortgage revenue bonds — — 671 — 671 Other — 10 357 — 367 Total available-for-sale securities — 3,530 1,313 — 4,843 Mortgage loans — 9,480 1,116 — 10,596 Other assets: Risk management derivatives: Swaps — 4,035 146 — 4,181 Swaptions — 108 — — 108 Other — — 22 — 22 Netting adjustment — — — (4,272 ) (4,272 ) Mortgage commitment derivatives — 131 1 — 132 Total other assets — 4,274 169 (4,272 ) 171 Total assets at fair value $ 29,222 $ 21,540 $ 3,799 $ (4,272 ) $ 50,289 Fair Value Measurements as of December 31, 2017 Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Netting Adjustment (1) Estimated Fair Value (Dollars in millions) Liabilities: Long-term debt: Of Fannie Mae: Senior floating $ — $ 7,810 $ 376 $ — $ 8,186 Total of Fannie Mae — 7,810 376 — 8,186 Of consolidated trusts — 29,911 582 — 30,493 Total long-term debt — 37,721 958 — 38,679 Other liabilities: Risk management derivatives: Swaps — 4,721 33 — 4,754 Swaptions — 324 — — 324 Other — — 1 — 1 Netting adjustment — — — (4,979 ) (4,979 ) Mortgage commitment derivatives — 227 1 — 228 Total other liabilities — 5,272 35 (4,979 ) 328 Total liabilities at fair value $ — $ 42,993 $ 993 $ (4,979 ) $ 39,007 __________ (1) Derivative contracts are reported on a gross basis by level. The netting adjustment represents the effect of the legal right to offset under legally enforceable master netting arrangements to settle with the same counterparty on a net basis, including cash collateral posted and received. (2) Cash equivalent are comprised of U.S. Treasuries that have a maturity at the date of acquisition of three months or less.
Fair Value Measurements Using Significant Unobservable Inputs (Level 3) [Table Text Block]	The following tables display a reconciliation of all assets and liabilities measured at fair value on a recurring basis using significant unobservable inputs (Level 3). The tables also display gains and losses due to changes in fair value, including realized and unrealized gains and losses, recognized in our condensed consolidated statements of operations and comprehensive income for Level 3 assets and liabilities. When assets and liabilities are transferred between levels, we recognize the transfer as of the end of the period. Fair Value Measurements Using Significant Unobservable Inputs (Level 3) For the Three Months Ended June 30, 2018 Net Unrealized Gains (Losses) Included in Net Income Related to Assets and Liabilities Still Held as of June 30, 2018 (5)(6) Total Gains (Losses) (Realized/Unrealized) Balance, March 31, 2018 Included in Net Income Included in Total Other Comprehensive Income (Loss) (1) Purchases Sales Issues (3) Settlements (3) Transfers out of Level 3 Transfers into Level 3 Balance, June 30, 2018 (Dollars in millions) Trading securities: Mortgage-related: Fannie Mae $ 83 $ (5 ) $ — $ — $ — $ — $ — $ — $ 1 $ 79 $ 3 Mortgage revenue bonds 1 — — — — — — — — 1 — Total trading securities $ 84 $ (5 ) (6)(7) $ — $ — $ — $ — $ — $ — $ 1 $ 80 $ 3 Available-for-sale securities: Mortgage-related: Fannie Mae $ 202 $ 1 $ 4 $ — $ — $ — $ (3 ) $ — $ — $ 204 $ — Alt-A and subprime private-label securities 27 — — — — — (1 ) — — 26 — Mortgage revenue bonds 539 (11 ) 10 — (7 ) — (25 ) — — 506 — Other 351 7 10 — — — (11 ) — — 357 — Total available-for-sale securities $ 1,119 $ (3 ) (7)(8) $ 24 $ — $ (7 ) $ — $ (40 ) $ — $ — $ 1,093 $ — Mortgage loans $ 1,102 $ 11 (6)(7) $ — $ — $ — $ — $ (79 ) $ (51 ) $ 35 $ 1,018 $ 8 Net derivatives 133 (28 ) (6) — — — — 12 — — 117 (14 ) Long-term debt: Of Fannie Mae: Senior floating $ (357 ) $ 3 $ — $ — $ — $ — $ — $ — $ — $ (354 ) $ 3 Of consolidated trusts (462 ) 4 — — — — 21 177 (59 ) (319 ) (1 ) Total long-term debt $ (819 ) $ 7 (6) $ — $ — $ — $ — $ 21 $ 177 $ (59 ) $ (673 ) $ 2 Fair Value Measurements Using Significant Unobservable Inputs (Level 3) For the Six Months Ended June 30, 2018 Net Unrealized Gains (Losses) Included in Net Income Related to Assets and Liabilities Still Held as of June 30, 2018 (5)(6) Total Gains (Losses) (Realized/Unrealized) Balance, December 31, 2017 Included in Net Income Included in Total Other Comprehensive Income (Loss) (1) Purchases (2) Sales (2) Issues (3) Settlements (3) Transfers out of Level 3 Transfers into Level 3 Balance, June 30, 2018 (Dollars in millions) Trading securities: Mortgage-related: Fannie Mae $ 971 $ 166 $ — $ 1 $ (1,060 ) $ — $ — $ — $ 1 $ 79 $ 3 Other agency 35 (1 ) — — — — (1 ) (33 ) — — — Alt-A and subprime private-label securities 194 (85 ) — — — — (5 ) (104 ) — — — Mortgage revenue bonds 1 — — — — — — — — 1 — Total trading securities $ 1,201 $ 80 (6)(7) $ — $ 1 $ (1,060 ) $ — $ (6 ) $ (137 ) $ 1 $ 80 $ 3 Available-for-sale securities: Mortgage-related: Fannie Mae $ 208 $ 1 $ — $ — $ — $ — $ (5 ) $ — $ — $ 204 $ — Alt-A and subprime private-label securities 77 — (45 ) — — — (2 ) (4 ) — 26 — Mortgage revenue bonds 671 — (3 ) — (18 ) — (144 ) — — 506 — Other 357 14 8 — — — (22 ) — — 357 — Total available-for-sale securities $ 1,313 $ 15 (7)(8) $ (40 ) $ — $ (18 ) $ — $ (173 ) $ (4 ) $ — $ 1,093 $ — Mortgage loans $ 1,116 $ 28 (6)(7) $ — $ — $ — $ — $ (127 ) $ (87 ) $ 88 $ 1,018 $ 16 Net derivatives 134 (86 ) (6) — — — — 16 53 — 117 (37 ) Long-term debt: Of Fannie Mae: Senior floating $ (376 ) $ 22 $ — $ — $ — $ — $ — $ — $ — $ (354 ) $ 22 Of consolidated trusts (582 ) 7 — — — 1 31 331 (107 ) (319 ) (1 ) Total long-term debt $ (958 ) $ 29 (6) $ — $ — $ — $ 1 $ 31 $ 331 $ (107 ) $ (673 ) $ 21 Fair Value Measurements Using Significant Unobservable Inputs (Level 3) For the Three Months Ended June 30, 2017 Net Unrealized Gains (Losses) Included in Net Income Related to Assets and Liabilities Still Held as of June 30, 2017 (5)(6) Total Gains (Losses) (Realized/Unrealized) Balance, March 31, 2017 Included in Net Income Included in Total Other Comprehensive Income (Loss) (1) Purchases (2) Sales (2) Issues (3) Settlements (3) Transfers out of Level 3 Transfers into Level 3 (4) Balance, June 30, 2017 (Dollars in millions) Trading securities: Mortgage-related: Fannie Mae $ 856 $ 1 $ — $ 63 $ — $ — $ (2 ) $ (21 ) $ 974 $ 1,871 $ — Alt-A and subprime private-label securities 272 3 — — — — (11 ) — — 264 2 Mortgage revenue bonds 20 3 — — (21 ) — (1 ) — — 1 — Total trading securities $ 1,148 $ 7 (6)(7) $ — $ 63 $ (21 ) $ — $ (14 ) $ (21 ) $ 974 $ 2,136 $ 2 Available-for-sale securities: Mortgage-related: Fannie Mae $ 232 $ — $ (3 ) $ — $ — $ — $ (2 ) $ (21 ) $ — $ 206 $ — Alt-A and subprime private-label securities 205 — (21 ) — — — (6 ) — — 178 — Mortgage revenue bonds 1,185 34 (11 ) — (312 ) — (23 ) — — 873 — Other 417 — (19 ) — — — (18 ) — — 380 — Total available-for-sale securities $ 2,039 $ 34 (7)(8) $ (54 ) $ — $ (312 ) $ — $ (49 ) $ (21 ) $ — $ 1,637 $ — Mortgage loans $ 1,149 $ 24 (6)(7) $ — $ — $ — $ — $ (55 ) $ (21 ) $ 22 $ 1,119 $ 19 Net derivatives 113 27 (6) — — — — (16 ) — — 124 9 Long-term debt: Of Fannie Mae: Senior floating $ (350 ) $ (15 ) $ — $ — $ — $ — $ — $ — $ — $ (365 ) $ (14 ) Of consolidated trusts (214 ) (5 ) — — — — 12 22 (575 ) (760 ) (5 ) Total long-term debt $ (564 ) $ (20 ) (6) $ — $ — $ — $ — $ 12 $ 22 $ (575 ) $ (1,125 ) $ (19 ) Fair Value Measurements Using Significant Unobservable Inputs (Level 3) For the Six Months Ended June 30, 2017 Net Unrealized Gains (Losses) Included in Net Income Related to Assets and Liabilities Still Held as of June 30, 2017 (5)(6) Total Gains (Losses) (Realized/Unrealized) Balance, December 31, 2016 Included in Net Income Included in Total Other Comprehensive Income (Loss) (1) Purchases (2) Sales (2) Issues (3) Settlements (3) Transfers out of Level 3 Transfers into Level 3 (4) Balance, June 30, 2017 (Dollars in millions) Trading securities: Mortgage-related: Fannie Mae $ 835 $ 4 $ — $ 63 $ — $ — $ (5 ) $ (22 ) $ 996 $ 1,871 $ 2 Alt-A and subprime private-label securities 271 11 — — — — (18 ) — — 264 11 Mortgage revenue bonds 21 3 — — (21 ) — (2 ) — — 1 — Total trading securities $ 1,127 $ 18 (6)(7) $ — $ 63 $ (21 ) $ — $ (25 ) $ (22 ) $ 996 $ 2,136 $ 13 Available-for-sale securities: Mortgage-related: Fannie Mae $ 230 $ 1 $ (2 ) $ — $ — $ — $ (6 ) $ (47 ) $ 30 $ 206 $ — Other agency 5 — — — (1 ) — — (4 ) — — — Alt-A and subprime private-label securities 217 — (15 ) — — — (24 ) — — 178 — Mortgage revenue bonds 1,272 35 (12 ) — (324 ) — (98 ) — — 873 — Other 429 — (14 ) — — — (35 ) — — 380 — Total available-for-sale securities $ 2,153 $ 36 (7)(8) $ (43 ) $ — $ (325 ) $ — $ (163 ) $ (51 ) $ 30 $ 1,637 $ — Mortgage loans $ 1,197 $ 32 (6)(7) $ — $ — $ — $ — $ (117 ) $ (67 ) $ 74 $ 1,119 $ 16 Net derivatives 44 100 (6) — — — — (24 ) 5 (1 ) 124 — Long-term debt: Of Fannie Mae: Senior floating $ (347 ) $ (18 ) $ — $ — $ — $ — $ — $ — $ — $ (365 ) $ (18 ) Of consolidated trusts (241 ) (4 ) — — — (2 ) 19 88 (620 ) (760 ) (4 ) Total long-term debt $ (588 ) $ (22 ) (6) $ — $ — $ — $ (2 ) $ 19 $ 88 $ (620 ) $ (1,125 ) $ (22 ) __________ (1) Gains (losses) included in other comprehensive income (loss) are included in “Changes in unrealized gains on AFS securities, net of reclassification adjustments and taxes” in our condensed consolidated statements of operations and comprehensive income. (2) Purchases and sales include activity related to the consolidation and deconsolidation of assets of securitization trusts. For the first half of 2018 , includes the dissolution of a Fannie Mae-wrapped private-label securities trust. (3) Issues and settlements include activity related to the consolidation and deconsolidation of liabilities of securitization trusts. (4) Transfers of Fannie Mae trading securities into Level 3 during the second quarter and first half of 2017 consisted primarily of a Fannie Mae security backed by private-label mortgage-related securities. Prices for this security were based on inputs that were not readily available. Transfers of long-term debt of consolidated trusts into Level 3 during the second quarter and first half of 2017 consisted of securities for which prices were estimated using inputs that were not readily available. (5) Amount represents temporary changes in fair value. Amortization, accretion and OTTI are not considered unrealized and are not included in this amount. (6) Gains (losses) are included in “ Fair value gains (losses), net ” in our condensed consolidated statements of operations and comprehensive income. (7) Gains (losses) are included in “ Net interest income ” in our condensed consolidated statements of operations and comprehensive income. (8) Gains (losses) are included in “ Investment gains, net ” in our condensed consolidated statements of operations and comprehensive income.
Valuation Techniques and Significant Unobservable Inputs for Level 3 Assets and Liabilities [Table Text Block]	The following tables display valuation techniques and the range and the weighted average of significant unobservable inputs for our Level 3 assets and liabilities measured at fair value on a recurring basis. Fair Value Measurements as of June 30, 2018 Fair Value Significant Valuation Techniques Significant Unobservable Inputs (1) Range (1) Weighted - Average (1) (Dollars in millions) Recurring fair value measurements: Trading securities: Mortgage-related securities: Agency (2) $ 79 Various Mortgage revenue bonds 1 Various Total trading securities $ 80 Available-for-sale securities: Mortgage-related securities: Agency (2) $ 204 Various Alt-A and subprime private-label securities 26 Various Mortgage revenue bonds 389 Single Vendor Spreads (bps) 1.5 - 320.4 51.0 117 Various Total mortgage revenue bonds 506 Other 305 Discounted Cash Flow Default Rate (%) 3.8 3.8 Prepayment Speed (%) 6.5 6.5 Severity (%) 95.0 95.0 Spreads (bps) 68.5 - 400.0 399.0 52 Various Total other 357 Total available-for-sale securities $ 1,093 Net derivatives $ 107 Dealer Mark 10 Various Total net derivatives $ 117 Fair Value Measurements as of December 31, 2017 Fair Value Significant Valuation Techniques Significant Unobservable Inputs (1) Range (1) Weighted - Average (1) (Dollars in millions) Recurring fair value measurements: Trading securities: Mortgage-related securities: Agency (2) $ 971 Single Vendor Prepayment Speed (%) 0.0 - 177.0 160.0 Spreads (bps) 51.5 - 375.0 200.1 35 Various Total agency 1,006 Alt-A and subprime private-label securities 154 Consensus 40 Various Total Alt-A and subprime private-label securities 194 Mortgage revenue bonds 1 Various Total trading securities $ 1,201 Available-for-sale securities: Mortgage-related securities: Agency (2) $ 112 Single Vendor Prepayment Speed (%) 0.0 - 175.7 147.1 Spreads (bps) 150.0 - 210.0 182.3 96 Various Total agency 208 Alt-A and subprime private-label securities 77 Various Mortgage revenue bonds 475 Single Vendor Spreads (bps) (17.0 ) - 248.0 39.0 196 Various Total mortgage revenue bonds 671 Other 325 Discounted Cash Flow Prepayment Speed (%) 1.6 - 2.5 2.5 Severity (%) 50.0 - 88.0 86.6 Spreads (bps) 84.8 - 607.0 577.9 32 Various Total other 357 Total available-for-sale securities $ 1,313 Net derivatives $ 113 Dealer Mark 21 Various Total net derivatives $ 134 _________ (1) Valuation techniques for which no unobservable inputs are disclosed generally reflect the use of third-party pricing services or dealers, and the range of unobservable inputs applied by these sources is not readily available or cannot be reasonably estimated. Where we have disclosed unobservable inputs for consensus and single vendor techniques, those inputs are based on our validations performed at the security level using discounted cash flows. The prepayment speed used for trading agency securities and available-for-sale agency securities is the Public Securities Association prepayment speed, which can be greater than 100%. For all other securities, the Conditional Prepayment Rate is used as the prepayment speed, which can be between 0% and 100%. (2) Includes Fannie Mae and Freddie Mac securities.
Level 3 Assets Measured on Nonrecurring Basis [Table Text Block]	The following table displays valuation techniques for our Level 3 assets measured at fair value on a nonrecurring basis. The significant unobservable inputs related to these techniques primarily relate to collateral dependent valuations. The related ranges and weighted averages are not meaningful when aggregated as they vary significantly from property to property. Fair Value Measurements as of Valuation Techniques June 30, 2018 December 31, 2017 (Dollars in millions) Nonrecurring fair value measurements: Mortgage loans held for sale, at lower of cost or fair value Single Vendor $ 618 $ 1,880 Consensus 4,427 1,113 Various 1 — Total mortgage loans held for sale, at lower of cost or fair value 5,046 2,993 Single-family mortgage loans held for investment, at amortized cost Internal Model 790 1,623 Multifamily mortgage loans held for investment, at amortized cost Asset Manager Estimate 131 163 Various 24 32 Total multifamily mortgage loans held for investment, at amortized cost 155 195 Acquired property, net: (1) Single-family Accepted Offers 181 218 Appraisals 386 438 Walk Forwards 154 222 Internal Model 211 319 Various 38 113 Total single-family 970 1,310 Multifamily Various 16 19 Other assets Various 1 2 Total nonrecurring assets at fair value $ 6,978 $ 6,142 __________ (1) The most commonly used techniques in our valuation of acquired property are proprietary home price model and third-party valuations (both current and walk forward). Based on the number of properties measured as of June 30, 2018 , these methodologies comprised approximately 76% of our valuations, while accepted offers comprised approximately 19% of our valuations. Based on the number of properties measured as of December 31, 2017 , these methodologies comprised approximately 77% of our valuations, while accepted offers comprised approximately 18% of our valuations.
Fair Value of Financial Instruments [Table Text Block]	The following table displays the carrying value and estimated fair value of our financial instruments. The fair value of financial instruments we disclose includes commitments to purchase multifamily and single-family mortgage loans that we do not record in our condensed consolidated balance sheets. The fair values of these commitments are included as “Mortgage loans held for investment, net of allowance for loan losses.” The disclosure excludes all non-financial instruments; therefore, the fair value of our financial assets and liabilities does not represent the underlying fair value of our total consolidated assets and liabilities. As of June 30, 2018 Carrying Quoted Prices in Active Markets for Identical Assets Significant Other Observable Inputs Significant Unobservable Inputs Netting Adjustment Estimated (Dollars in millions) Financial assets: Cash and cash equivalents and restricted cash $ 48,729 $ 37,679 $ 11,050 $ — $ — $ 48,729 Federal funds sold and securities purchased under agreements to resell or similar arrangements 16,300 — 16,300 — — 16,300 Trading securities 42,381 35,663 6,638 80 — 42,381 Available-for-sale securities 3,723 — 2,630 1,093 — 3,723 Mortgage loans held for sale 14,323 — 1,436 13,894 — 15,330 Mortgage loans held for investment, net of allowance for loan losses 3,194,301 — 2,917,541 231,082 — 3,148,623 Advances to lenders 3,901 — 3,899 2 — 3,901 Derivative assets at fair value 372 — 2,851 129 (2,608 ) 372 Guaranty assets and buy-ups 151 — — 370 — 370 Total financial assets $ 3,324,181 $ 73,342 $ 2,962,345 $ 246,650 $ (2,608 ) $ 3,279,729 Financial liabilities: Short-term debt: Of Fannie Mae $ 25,726 $ — $ 25,730 $ — $ — $ 25,730 Of consolidated trusts 339 — — 338 — 338 Long-term debt: Of Fannie Mae 224,964 — 228,853 791 — 229,644 Of consolidated trusts 3,086,460 — 2,973,785 40,988 — 3,014,773 Derivative liabilities at fair value 604 — 3,348 12 (2,756 ) 604 Guaranty obligations 163 — — 121 — 121 Total financial liabilities $ 3,338,256 $ — $ 3,231,716 $ 42,250 $ (2,756 ) $ 3,271,210 As of December 31, 2017 Carrying Quoted Prices in Active Markets for Identical Assets Significant Other Observable Inputs Significant Unobservable Inputs Netting Adjustment Estimated (Dollars in millions) Financial assets: Cash and cash equivalents and restricted cash $ 60,260 $ 35,060 $ 25,200 $ — $ — $ 60,260 Federal funds sold and securities purchased under agreements to resell or similar arrangements 19,470 — 19,470 — — 19,470 Trading securities 34,679 29,222 4,256 1,201 — 34,679 Available-for-sale securities 4,843 — 3,530 1,313 — 4,843 Mortgage loans held for sale 4,988 — 101 5,333 — 5,434 Mortgage loans held for investment, net of allowance for loan losses 3,173,537 — 2,886,470 315,719 — 3,202,189 Advances to lenders 4,938 — 4,936 2 — 4,938 Derivative assets at fair value 171 — 4,274 169 (4,272 ) 171 Guaranty assets and buy-ups 149 — — 436 — 436 Total financial assets $ 3,303,035 $ 64,282 $ 2,948,237 $ 324,173 $ (4,272 ) $ 3,332,420 Financial liabilities: Short-term debt: Of Fannie Mae $ 33,377 $ — $ 33,379 $ — $ — $ 33,379 Of consolidated trusts 379 — — 378 — 378 Long-term debt: Of Fannie Mae 243,375 — 249,780 837 — 250,617 Of consolidated trusts 3,052,923 — 3,014,250 40,683 — 3,054,933 Derivative liabilities at fair value 328 — 5,272 35 (4,979 ) 328 Guaranty obligations 258 — — 456 — 456 Total financial liabilities $ 3,330,640 $ — $ 3,302,681 $ 42,389 $ (4,979 ) $ 3,340,091
Fair Value Option [Table Text Block]	The following table displays the fair value and unpaid principal balance of the financial instruments for which we have made fair value elections. As of June 30, 2018 December 31, 2017 Loans (1) Long-Term Debt of Fannie Mae Long-Term Debt of Consolidated Trusts Loans (1) Long-Term Debt of Fannie Mae Long-Term Debt of Consolidated Trusts (Dollars in millions) Fair value $ 9,628 $ 7,558 $ 26,675 $ 10,596 $ 8,186 $ 30,493 Unpaid principal balance 9,510 6,780 24,695 10,246 7,368 27,717 __________ (1) Includes nonaccrual loans with a fair value of $181 million and $227 million as of June 30, 2018 and December 31, 2017 , respectively. The difference between unpaid principal balance and the fair value of these nonaccrual loans as of June 30, 2018 and December 31, 2017 was $28 million and $46 million , respectively. Includes loans that are 90 days or more past due with a fair value of $131 million and $159 million as of June 30, 2018 and December 31, 2017 , respectively. The difference between unpaid principal balance and the fair value of these 90 or more days past due loans as of June 30, 2018 and December 31, 2017 was $22 million and $34 million , respectively.

Summary of Significant Accoun43

Summary of Significant Accounting Policies Regulatory Capital (Details) - USD ($) $ in Billions	Jun. 30, 2018	Dec. 31, 2017
Accounting Policies [Abstract]
Deficit of core capital over statutory minimum capital requirement	$ 136.3	$ 144.4

Summary of Significant Accoun44

Summary of Significant Accounting Policies Related Parties (Details) - USD ($) shares in Millions, $ in Millions	3 Months Ended				6 Months Ended		12 Months Ended
	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016
Related Parties [Line Items]
Net worth		$ 7,459	$ 3,900		$ 7,459		$ (3,686)
Payments of cash dividends on senior preferred stock to Treasury		938	0		938	$ 8,250
Income Taxes Paid		$ 460		$ 1,100	$ 460	$ 1,070
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent					21.00%		35.00%
Effective Income Tax Rate Reconciliation, Percent		20.30%		33.20%	20.60%	33.20%
Weighted Average Number of Shares, Contingently Issuable					4,600	4,600
Unpaid principal balance guaranteed by a related party		$ 4,700			$ 4,700
Temporary Payroll Tax Cut Continuation Act of 2011 (“TCCA”) fees		$ 565		$ 518	$ 1,122	$ 1,021
Basis Points of Each Dollar of Unpaid Principal Balance		0.042%			0.042%
Trading, at fair value (includes $3,363 and $747, respectively, pledged as collateral)		$ 42,381			$ 42,381		$ 34,679
Interest Receivable		8,256			8,256		8,133
Interest income recognized on Treasury securities		$ 318		176	$ 554	$ 318
Incremental Common Shares Attributable to Dilutive Effect of Conversion of Preferred Stock		0			131	131
Scenario, Forecast [Member]
Related Parties [Line Items]
Expected undeclared dividends payable on senior preferred stock for the next quarter	$ 4,500
US Treasury [Member]
Related Parties [Line Items]
Aggregate Funding Received From US Treasury Pursuant To the Senior Preferred Stock Purchase Agreement During Period			3,700
Aggregate funding received from US Treasury pursuant to the senior preferred stock purchase agreement		$ 119,800			$ 119,800
Total available funding from US Treasury pursuant to the senior preferred stock agreement		113,900			113,900
Capital Reserve Amount, current year, Senior Preferred Stock Purchase Agreement, Amendment		3,000			3,000
Aggregate liquidation preference of senior preferred stock		$ 123,800			$ 123,800
Percentage of common shares attributable to warrants issued to US Treasury as percentage to total diluted common shares		79.90%			79.90%
Home Affordable Modification Program administrative expense reimbursements from Treasury and Freddie Mac		$ 6		11	$ 13	$ 23
Percentage of initial principal loss US Treasury will bear for New Issue Bond Program		35.00%			35.00%
Temporary Payroll Tax Cut Continuation Act of 2011 (“TCCA”) fees		$ 565		518	$ 1,122	1,021
US Treasury [Member] | Single-family [Member]
Related Parties [Line Items]
Recognized TCCA fees that had not been remitted to Treasury as of period end		565			565
Freddie Mac [Member] | Freddie Mac [Member]
Related Parties [Line Items]
Interest Receivable		2			2		2
Fair value of mortgage-related securities		543			543		613
Interest income recognized on mortgage-related securities		6		10	13	23
Federal Housing Finance Agency [Member]
Related Parties [Line Items]
FHFA assessment fees		26		26	55	56
Common Securitization Solutions [Member]
Related Parties [Line Items]
Payments to Acquire or Advance to Equity Method Investments		35		18	76	53
U.S. Treasury securities [Member]
Related Parties [Line Items]
Trading, at fair value (includes $3,363 and $747, respectively, pledged as collateral)		35,663			35,663		29,222
U.S. Treasury securities [Member] | US Treasury [Member]
Related Parties [Line Items]
Trading, at fair value (includes $3,363 and $747, respectively, pledged as collateral)		35,700			35,700		29,200
Interest Receivable		116			116		77
Interest income recognized on Treasury securities		164		86	293	149
Other Expense [Member] | US Treasury [Member]
Related Parties [Line Items]
Affordable Housing Program Assessments		19		15	37	30
Recognized affordable housing program expenses that had not been remitted to Treasury as of period end		37			37
Accumulated other comprehensive income [Member]
Related Parties [Line Items]
Tax Cuts and Jobs Act, Reclassification from AOCI to Retained Earnings, Tax Effect		0		0	117	0
Net worth		$ 349	$ 347	$ 682	$ 349	$ 682	$ 553	$ 765	$ 759

Consolidations and Transfers 45

Consolidations and Transfers of Financial Assets Unconsolidated VIEs (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Variable Interest Entities [Line Items]
Trading, at fair value	$ 42,381	$ 34,679
Available-for-sale, at fair value	3,723	4,843
Other assets	17,160	19,049
Other liabilities	(8,591)	(9,479)
Unpaid principal balance of mortgage loans	3,186,600	3,155,703
Multifamily [Member]
Variable Interest Entities [Line Items]
Unpaid principal balance of mortgage loans	275,797	265,069
Unconsolidated VIEs [Member] | Mortgage-related securities [Member]
Variable Interest Entities [Line Items]
Trading, at fair value	6,565	5,389
Available-for-sale, at fair value	3,147	4,094
Other assets	70	74
Other liabilities	(104)	(467)
Net carrying amount	9,678	9,090
Maximum exposure to loss	14,000	15,000
Total unconsolidated assets	70,000	70,000
Unconsolidated VIEs [Member] | Partnership interest [Member]
Variable Interest Entities [Line Items]
Net carrying amount	81	82
Maximum exposure to loss	103	105
Total unconsolidated assets	3,000	3,200
Unconsolidated VIEs [Member] | Fannie Mae Securities [Member]
Variable Interest Entities [Line Items]
Trading, at fair value	1,640	3,809
Available-for-sale, at fair value	1,825	2,032
Unconsolidated VIEs [Member] | Non-Fannie Mae Securities [Member]
Variable Interest Entities [Line Items]
Trading, at fair value	4,925	1,580
Available-for-sale, at fair value	$ 1,322	$ 2,062

Consolidations and Transfers 46

Consolidations and Transfers of Financial Assets Transfers of Financial Assets (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Transfers of Financial Assets [Line Items]
Portfolio securitizations: unpaid principal balance	$ 51,600	$ 69,200	$ 115,900	$ 126,500
Unconsolidated VIEs [Member]
Transfers of Financial Assets [Line Items]
Retained interests: principal and interest received	128	$ 303	354	$ 560
Unconsolidated VIEs [Member] | Single Class MBS, REMIC & Megas [Member]
Transfers of Financial Assets [Line Items]
Retained interests: unpaid principal balance	1,600		1,600		$ 3,900
Retained interests: fair value	$ 2,500		$ 2,500		$ 4,700

Consolidations and Transfers 47

Consolidations and Transfers of Financial Assets Managed Loans (Details) - USD ($) $ in Billions	Jun. 30, 2018	Dec. 31, 2017
Consolidations and Transfers of Financial Assets [Abstract]
Principal Amount Outstanding on Loans Securitized or Asset-backed Financing Arrangement	$ 1.2	$ 1.3

Mortgage Loans Loans in Mortgag

Mortgage Loans Loans in Mortgage Portfolio (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016
Loans in Mortgage Portfolio [Line Items]
Unpaid principal balance of mortgage loans	$ 3,186,600		$ 3,186,600			$ 3,155,703
Cost basis and fair value adjustments, net	38,836		38,836			41,906
Allowance for loan losses for loans held for investment	(16,812)	$ (20,399)	(16,812)	$ (20,399)	$ (18,734)	(19,084)	$ (22,129)	$ (23,465)
Total mortgage loans	3,208,624		3,208,624			3,178,525
Carrying value of loans redesignated from HFI to HFS	6,235	2,879	13,602	5,422
Carrying value of loans redesignated from HFS to HFI	12	17	30	52
Loans sold - unpaid principal balance	3,710	2,947	4,458	3,040
Realized gains on sale of mortgage loans	210	$ 55	208	$ 53
Single-family [Member]
Loans in Mortgage Portfolio [Line Items]
Unpaid principal balance of mortgage loans	2,910,803		2,910,803			2,890,634
Mortgage Loans in Process of Foreclosure, Amount	12,000		12,000			13,000
Multifamily [Member]
Loans in Mortgage Portfolio [Line Items]
Unpaid principal balance of mortgage loans	$ 275,797		$ 275,797			$ 265,069

Mortgage Loans Aging (Details)

Mortgage Loans Aging (Details) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Financing Receivable, Recorded Investment, Past Due [Line Items]
Days delinquent	$ 62,341	$ 81,160
Current	3,147,165	3,108,815
Total recorded investment in loans	3,209,506	3,189,975
Recorded investment in loans 90 days or more delinquent and accruing interest	221	303
Recorded investment in nonaccrual loans	34,460	45,323
30 to 59 Days Delinquent [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Days delinquent	32,339	40,034
60 to 89 Days Delinquent [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Days delinquent	8,082	11,975
Seriously Delinquent [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Days delinquent	21,920	29,151
Single-family [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Days delinquent	61,981	80,858
Current	2,870,058	2,842,116
Total recorded investment in loans	2,932,039	2,922,974
Recorded investment in loans 90 days or more delinquent and accruing interest	221	303
Recorded investment in nonaccrual loans	$ 33,841	$ 44,899
Single-family [Member] | Minimum [Member]
Table Footnote [Abstract]
Serious delinquency, days past due	90 days	90 days
Single-family [Member] | 30 to 59 Days Delinquent [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Days delinquent	$ 32,326	$ 40,008
Single-family [Member] | 60 to 89 Days Delinquent [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Days delinquent	8,082	11,975
Single-family [Member] | Seriously Delinquent [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Days delinquent	21,573	28,875
Single-family [Member] | Primary [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Days delinquent	53,611	69,977
Current	2,776,694	2,732,818
Total recorded investment in loans	2,830,305	2,802,795
Recorded investment in loans 90 days or more delinquent and accruing interest	29	87
Recorded investment in nonaccrual loans	28,570	37,971
Single-family [Member] | Primary [Member] | 30 to 59 Days Delinquent [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Days delinquent	28,773	35,582
Single-family [Member] | Primary [Member] | 60 to 89 Days Delinquent [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Days delinquent	6,876	10,396
Single-family [Member] | Primary [Member] | Seriously Delinquent [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Days delinquent	17,962	23,999
Single-family [Member] | Government [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Days delinquent	251	282
Current	24,068	30,807
Total recorded investment in loans	24,319	31,089
Recorded investment in loans 90 days or more delinquent and accruing interest	185	206
Recorded investment in nonaccrual loans	0	0
Single-family [Member] | Government [Member] | 30 to 59 Days Delinquent [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Days delinquent	49	55
Single-family [Member] | Government [Member] | 60 to 89 Days Delinquent [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Days delinquent	17	21
Single-family [Member] | Government [Member] | Seriously Delinquent [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Days delinquent	185	206
Single-family [Member] | Alt-A [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Days delinquent	5,930	7,751
Current	53,395	59,475
Total recorded investment in loans	59,325	67,226
Recorded investment in loans 90 days or more delinquent and accruing interest	4	5
Recorded investment in nonaccrual loans	3,854	5,094
Single-family [Member] | Alt-A [Member] | 30 to 59 Days Delinquent [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Days delinquent	2,569	3,186
Single-family [Member] | Alt-A [Member] | 60 to 89 Days Delinquent [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Days delinquent	876	1,147
Single-family [Member] | Alt-A [Member] | Seriously Delinquent [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Days delinquent	2,485	3,418
Single-family [Member] | Other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Days delinquent	2,189	2,848
Current	15,901	19,016
Total recorded investment in loans	18,090	21,864
Recorded investment in loans 90 days or more delinquent and accruing interest	3	5
Recorded investment in nonaccrual loans	1,417	1,834
Single-family [Member] | Other [Member] | 30 to 59 Days Delinquent [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Days delinquent	935	1,185
Single-family [Member] | Other [Member] | 60 to 89 Days Delinquent [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Days delinquent	313	411
Single-family [Member] | Other [Member] | Seriously Delinquent [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Days delinquent	941	1,252
Multifamily [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Days delinquent	360	302
Current	277,107	266,699
Total recorded investment in loans	277,467	267,001
Recorded investment in loans 90 days or more delinquent and accruing interest	0	0
Recorded investment in nonaccrual loans	$ 619	$ 424
Multifamily [Member] | Minimum [Member]
Table Footnote [Abstract]
Serious delinquency, days past due	60 days	60 days
Multifamily [Member] | Maximum [Member]
Table Footnote [Abstract]
Serious delinquency, days past due	89 days	89 days
Multifamily [Member] | 30 to 59 Days Delinquent [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Days delinquent	$ 13	$ 26
Multifamily [Member] | Seriously Delinquent [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Days delinquent	$ 347	$ 276

Mortgage Loans Credit Quality I

Mortgage Loans Credit Quality Indicators - SF (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Financing Receivable, Recorded Investment [Line Items]
Total recorded investment in loans	$ 3,209,506	$ 3,189,975
Single-family [Member]
Financing Receivable, Recorded Investment [Line Items]
Total recorded investment in loans	2,932,039	2,922,974
Single-family [Member] | Primary [Member]
Financing Receivable, Recorded Investment [Line Items]
Total recorded investment in loans	2,830,305	2,802,795
Single-family [Member] | Primary [Member] | Estimated mark-to-market loan-to-value ratio less than or equal to 80% [Member]
Financing Receivable, Recorded Investment [Line Items]
Total recorded investment in loans	2,516,133	2,439,858
Single-family [Member] | Primary [Member] | Estimated mark-to-market loan-to-value ratio greater than 80% and less than or equal to 90% [Member]
Financing Receivable, Recorded Investment [Line Items]
Total recorded investment in loans	218,193	238,038
Single-family [Member] | Primary [Member] | Estimated mark-to-market loan-to-value ratio greater than 90% and less than or equal to 100% [Member]
Financing Receivable, Recorded Investment [Line Items]
Total recorded investment in loans	83,243	106,076
Single-family [Member] | Primary [Member] | Estimated mark-to-market loan-to-value ratio greater than 100% [Member]
Financing Receivable, Recorded Investment [Line Items]
Total recorded investment in loans	12,736	18,823
Single-family [Member] | Alt-A [Member]
Financing Receivable, Recorded Investment [Line Items]
Total recorded investment in loans	59,325	67,226
Single-family [Member] | Alt-A [Member] | Estimated mark-to-market loan-to-value ratio less than or equal to 80% [Member]
Financing Receivable, Recorded Investment [Line Items]
Total recorded investment in loans	49,011	51,903
Single-family [Member] | Alt-A [Member] | Estimated mark-to-market loan-to-value ratio greater than 80% and less than or equal to 90% [Member]
Financing Receivable, Recorded Investment [Line Items]
Total recorded investment in loans	4,846	6,680
Single-family [Member] | Alt-A [Member] | Estimated mark-to-market loan-to-value ratio greater than 90% and less than or equal to 100% [Member]
Financing Receivable, Recorded Investment [Line Items]
Total recorded investment in loans	2,675	4,044
Single-family [Member] | Alt-A [Member] | Estimated mark-to-market loan-to-value ratio greater than 100% [Member]
Financing Receivable, Recorded Investment [Line Items]
Total recorded investment in loans	2,793	4,599
Single-family [Member] | Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Total recorded investment in loans	18,090	21,864
Single-family [Member] | Other [Member] | Estimated mark-to-market loan-to-value ratio less than or equal to 80% [Member]
Financing Receivable, Recorded Investment [Line Items]
Total recorded investment in loans	14,537	16,428
Single-family [Member] | Other [Member] | Estimated mark-to-market loan-to-value ratio greater than 80% and less than or equal to 90% [Member]
Financing Receivable, Recorded Investment [Line Items]
Total recorded investment in loans	1,585	2,277
Single-family [Member] | Other [Member] | Estimated mark-to-market loan-to-value ratio greater than 90% and less than or equal to 100% [Member]
Financing Receivable, Recorded Investment [Line Items]
Total recorded investment in loans	940	1,443
Single-family [Member] | Other [Member] | Estimated mark-to-market loan-to-value ratio greater than 100% [Member]
Financing Receivable, Recorded Investment [Line Items]
Total recorded investment in loans	1,028	1,716
Single-family [Member] | Government [Member]
Financing Receivable, Recorded Investment [Line Items]
Total recorded investment in loans	$ 24,319	$ 31,089

Mortgage Loans Credit Quality51

Mortgage Loans Credit Quality Indicators - MF (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Financing Receivable, Recorded Investment [Line Items]
Total recorded investment in loans	$ 3,209,506	$ 3,189,975
Multifamily [Member]
Financing Receivable, Recorded Investment [Line Items]
Total recorded investment in loans	277,467	267,001
Multifamily [Member] | Non-Classified [Member]
Financing Receivable, Recorded Investment [Line Items]
Total recorded investment in loans	273,064	263,416
Multifamily [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Total recorded investment in loans	$ 4,403	$ 3,585

Mortgage Loans Individually Imp

Mortgage Loans Individually Impaired Loans (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	$ 115,651	$ 128,821	$ 116,444	$ 131,674
Individually impaired loans with related allowance recorded: unpaid principal balance	116,329		116,329		$ 123,314
Individually impaired loans with related allowance recorded: total recorded investment	110,636		110,636		116,474
Related allowance for loan losses	(15,921)		(15,921)		(17,289)
Individually impaired loans with no related allowance recorded: unpaid principal balance	20,102		20,102		20,642
Individually impaired loans with no related allowance recorded: total recorded investment	18,909		18,909		19,307
Total individually impaired loans: unpaid principal balance	136,431		136,431		143,956
Total individually impaired loans: total recorded investment	129,545		129,545		135,781
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method	1,217	1,283	2,414	2,610
Impaired Financing Receivable, with Related Allowance, Interest Income, Cash Basis Method	131	96	259	204
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	18,934	19,478	19,045	19,486
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method	322	369	641	758
Impaired Financing Receivable, with No Related Allowance, Interest Income, Cash Basis Method	38	27	69	54
Impaired Financing Receivable, Average Recorded Investment	134,585	148,299	135,489	151,160
Impaired Financing Receivable, Interest Income, Accrual Method	1,539	1,652	3,055	3,368
Impaired Financing Receivable, Interest Income, Cash Basis Method	169	123	328	258
Single-family [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	115,419	128,562	116,196	131,394
Individually impaired loans with related allowance recorded: unpaid principal balance	116,100		116,100		123,035
Individually impaired loans with related allowance recorded: total recorded investment	110,406		110,406		116,194
Related allowance for loan losses	(15,882)		(15,882)		(17,247)
Individually impaired loans with no related allowance recorded: unpaid principal balance	19,748		19,748		20,334
Individually impaired loans with no related allowance recorded: total recorded investment	18,553		18,553		18,997
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method	1,216	1,279	2,413	2,604
Impaired Financing Receivable, with Related Allowance, Interest Income, Cash Basis Method	131	96	259	204
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	18,579	19,194	18,705	19,208
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method	321	362	638	748
Impaired Financing Receivable, with No Related Allowance, Interest Income, Cash Basis Method	38	27	69	54
Impaired Financing Receivable, Interest Income, Accrual Method	1,500	1,700	3,100	3,400
Single-family [Member] | Primary [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	88,526	94,599	88,342	96,395
Individually impaired loans with related allowance recorded: unpaid principal balance	89,828		89,828		91,194
Individually impaired loans with related allowance recorded: total recorded investment	86,148		86,148		86,864
Related allowance for loan losses	(11,258)		(11,258)		(11,652)
Individually impaired loans with no related allowance recorded: unpaid principal balance	15,904		15,904		16,027
Individually impaired loans with no related allowance recorded: total recorded investment	15,086		15,086		15,158
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method	915	955	1,826	1,941
Impaired Financing Receivable, with Related Allowance, Interest Income, Cash Basis Method	109	77	216	165
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	14,942	15,091	14,988	15,050
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method	243	273	486	562
Impaired Financing Receivable, with No Related Allowance, Interest Income, Cash Basis Method	32	24	58	47
Single-family [Member] | Government [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	279	295	278	298
Individually impaired loans with related allowance recorded: unpaid principal balance	274		274		276
Individually impaired loans with related allowance recorded: total recorded investment	279		279		279
Related allowance for loan losses	(58)		(58)		(56)
Individually impaired loans with no related allowance recorded: unpaid principal balance	61		61		66
Individually impaired loans with no related allowance recorded: total recorded investment	56		56		60
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method	9	2	12	5
Impaired Financing Receivable, with Related Allowance, Interest Income, Cash Basis Method	0	0	0	0
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	57	61	58	61
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method	2	1	2	2
Impaired Financing Receivable, with No Related Allowance, Interest Income, Cash Basis Method	0	0	0	0
Single-family [Member] | Alt-A [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	19,349	24,249	20,020	24,896
Individually impaired loans with related allowance recorded: unpaid principal balance	19,098		19,098		23,077
Individually impaired loans with related allowance recorded: total recorded investment	17,475		17,475		21,045
Related allowance for loan losses	(3,314)		(3,314)		(4,046)
Individually impaired loans with no related allowance recorded: unpaid principal balance	2,915		2,915		3,253
Individually impaired loans with no related allowance recorded: total recorded investment	2,608		2,608		2,870
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method	219	240	431	489
Impaired Financing Receivable, with Related Allowance, Interest Income, Cash Basis Method	16	14	32	29
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	2,723	3,026	2,781	3,056
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method	61	67	119	140
Impaired Financing Receivable, with No Related Allowance, Interest Income, Cash Basis Method	5	2	9	5
Single-family [Member] | Other [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	7,265	9,419	7,556	9,805
Individually impaired loans with related allowance recorded: unpaid principal balance	6,900		6,900		8,488
Individually impaired loans with related allowance recorded: total recorded investment	6,504		6,504		8,006
Related allowance for loan losses	(1,252)		(1,252)		(1,493)
Individually impaired loans with no related allowance recorded: unpaid principal balance	868		868		988
Individually impaired loans with no related allowance recorded: total recorded investment	803		803		909
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method	73	82	144	169
Impaired Financing Receivable, with Related Allowance, Interest Income, Cash Basis Method	6	5	11	10
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	857	1,016	878	1,041
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method	15	21	31	44
Impaired Financing Receivable, with No Related Allowance, Interest Income, Cash Basis Method	1	1	2	2
Multifamily [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	232	259	248	280
Individually impaired loans with related allowance recorded: unpaid principal balance	229		229		279
Individually impaired loans with related allowance recorded: total recorded investment	230		230		280
Related allowance for loan losses	(39)		(39)		(42)
Individually impaired loans with no related allowance recorded: unpaid principal balance	354		354		308
Individually impaired loans with no related allowance recorded: total recorded investment	356		356		$ 310
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method	1	4	1	6
Impaired Financing Receivable, with Related Allowance, Interest Income, Cash Basis Method	0	0	0	0
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	355	284	340	278
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method	1	7	3	10
Impaired Financing Receivable, with No Related Allowance, Interest Income, Cash Basis Method	$ 0	$ 0	$ 0	$ 0

Mortgage Loans Individually I53

Mortgage Loans Individually Impaired Loans - 2 (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Financing Receivable, Impaired [Line Items]
Individually impaired loans with related allowance recorded: average recorded investment	$ 115,651	$ 128,821	$ 116,444	$ 131,674
Individually impaired loans with related allowance recorded: total interest income recognized	1,217	1,283	2,414	2,610
Individually impaired loans with related allowance recorded: interest income recognized on a cash basis	131	96	259	204
Individually impaired loans with no related allowance recorded: average recorded investment	18,934	19,478	19,045	19,486
Individually impaired loans with no related allowance recorded: total interest income recognized	322	369	641	758
Individually impaired loans with no related allowance recorded: interest income recognized on a cash basis	38	27	69	54
Individually impaired loans: average recorded investment	134,585	148,299	135,489	151,160
Individually impaired loans: total interest income recognized	1,539	1,652	3,055	3,368
Individually impaired loans: interest income recognized on a cash basis	169	123	328	258
Table Footnote [Abstract]
Individually impaired loans: total interest income recognized	1,539	1,652	3,055	3,368
Single-family [Member]
Financing Receivable, Impaired [Line Items]
Individually impaired loans with related allowance recorded: average recorded investment	115,419	128,562	116,196	131,394
Individually impaired loans with related allowance recorded: total interest income recognized	1,216	1,279	2,413	2,604
Individually impaired loans with related allowance recorded: interest income recognized on a cash basis	131	96	259	204
Individually impaired loans with no related allowance recorded: average recorded investment	18,579	19,194	18,705	19,208
Individually impaired loans with no related allowance recorded: total interest income recognized	321	362	638	748
Individually impaired loans with no related allowance recorded: interest income recognized on a cash basis	38	27	69	54
Individually impaired loans: total interest income recognized	1,500	1,700	3,100	3,400
Table Footnote [Abstract]
Troubled debt restructuring recorded investment	128,500		128,500		$ 134,700
Individually impaired loans: total interest income recognized	1,500	1,700	3,100	3,400
Individually impaired loans: contractual interest income	1,400	1,500	2,700	2,900
Individually impaired loans: effective yield adjustments	186	229	352	497
Single-family [Member] | Primary [Member]
Financing Receivable, Impaired [Line Items]
Individually impaired loans with related allowance recorded: average recorded investment	88,526	94,599	88,342	96,395
Individually impaired loans with related allowance recorded: total interest income recognized	915	955	1,826	1,941
Individually impaired loans with related allowance recorded: interest income recognized on a cash basis	109	77	216	165
Individually impaired loans with no related allowance recorded: average recorded investment	14,942	15,091	14,988	15,050
Individually impaired loans with no related allowance recorded: total interest income recognized	243	273	486	562
Individually impaired loans with no related allowance recorded: interest income recognized on a cash basis	32	24	58	47
Single-family [Member] | Government [Member]
Financing Receivable, Impaired [Line Items]
Individually impaired loans with related allowance recorded: average recorded investment	279	295	278	298
Individually impaired loans with related allowance recorded: total interest income recognized	9	2	12	5
Individually impaired loans with related allowance recorded: interest income recognized on a cash basis	0	0	0	0
Individually impaired loans with no related allowance recorded: average recorded investment	57	61	58	61
Individually impaired loans with no related allowance recorded: total interest income recognized	2	1	2	2
Individually impaired loans with no related allowance recorded: interest income recognized on a cash basis	0	0	0	0
Single-family [Member] | Alt-A [Member]
Financing Receivable, Impaired [Line Items]
Individually impaired loans with related allowance recorded: average recorded investment	19,349	24,249	20,020	24,896
Individually impaired loans with related allowance recorded: total interest income recognized	219	240	431	489
Individually impaired loans with related allowance recorded: interest income recognized on a cash basis	16	14	32	29
Individually impaired loans with no related allowance recorded: average recorded investment	2,723	3,026	2,781	3,056
Individually impaired loans with no related allowance recorded: total interest income recognized	61	67	119	140
Individually impaired loans with no related allowance recorded: interest income recognized on a cash basis	5	2	9	5
Single-family [Member] | Other [Member]
Financing Receivable, Impaired [Line Items]
Individually impaired loans with related allowance recorded: average recorded investment	7,265	9,419	7,556	9,805
Individually impaired loans with related allowance recorded: total interest income recognized	73	82	144	169
Individually impaired loans with related allowance recorded: interest income recognized on a cash basis	6	5	11	10
Individually impaired loans with no related allowance recorded: average recorded investment	857	1,016	878	1,041
Individually impaired loans with no related allowance recorded: total interest income recognized	15	21	31	44
Individually impaired loans with no related allowance recorded: interest income recognized on a cash basis	1	1	2	2
Multifamily [Member]
Financing Receivable, Impaired [Line Items]
Individually impaired loans with related allowance recorded: average recorded investment	232	259	248	280
Individually impaired loans with related allowance recorded: total interest income recognized	1	4	1	6
Individually impaired loans with related allowance recorded: interest income recognized on a cash basis	0	0	0	0
Individually impaired loans with no related allowance recorded: average recorded investment	355	284	340	278
Individually impaired loans with no related allowance recorded: total interest income recognized	1	7	3	10
Individually impaired loans with no related allowance recorded: interest income recognized on a cash basis	0	$ 0	0	$ 0
Table Footnote [Abstract]
Troubled debt restructuring recorded investment	$ 211		$ 211		$ 185

Mortgage Loans TDRs (Details)

Mortgage Loans TDRs (Details) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018USD ($)contracts	Jun. 30, 2017USD ($)contracts	Jun. 30, 2018USD ($)contracts	Jun. 30, 2017USD ($)contracts
Financing Receivable, Modifications [Line Items]
Average term extension of a single-family modified loan	128 months	155 months	133 months	154 months
Average interest rate reduction of a single-family modified loan	0.13%	0.67%	0.18%	0.80%
Number of loans troubled debt restructurings activity | contracts	23,671	15,795	68,033	34,965
Recorded investment troubled debt restructurings activity | $	$ 3,421	$ 2,206	$ 10,358	$ 4,852
Single-family [Member]
Financing Receivable, Modifications [Line Items]
Number of loans troubled debt restructurings activity | contracts	23,669	15,792	68,023	34,962
Recorded investment troubled debt restructurings activity | $	$ 3,402	$ 2,189	$ 10,297	$ 4,835
Single-family [Member] | Primary [Member]
Financing Receivable, Modifications [Line Items]
Number of loans troubled debt restructurings activity | contracts	21,820	14,148	63,499	31,383
Recorded investment troubled debt restructurings activity | $	$ 3,148	$ 1,945	$ 9,672	$ 4,308
Single-family [Member] | Government [Member]
Financing Receivable, Modifications [Line Items]
Number of loans troubled debt restructurings activity | contracts	26	45	74	106
Recorded investment troubled debt restructurings activity | $	$ 2	$ 4	$ 6	$ 10
Single-family [Member] | Alt-A [Member]
Financing Receivable, Modifications [Line Items]
Number of loans troubled debt restructurings activity | contracts	1,538	1,328	3,720	2,893
Recorded investment troubled debt restructurings activity | $	$ 200	$ 194	$ 483	$ 418
Single-family [Member] | Other [Member]
Financing Receivable, Modifications [Line Items]
Number of loans troubled debt restructurings activity | contracts	285	271	730	580
Recorded investment troubled debt restructurings activity | $	$ 52	$ 46	$ 136	$ 99
Multifamily [Member]
Financing Receivable, Modifications [Line Items]
Number of loans troubled debt restructurings activity | contracts	2	3	10	3
Recorded investment troubled debt restructurings activity | $	$ 19	$ 17	$ 61	$ 17

Mortgage Loans TDRs with Sub De

Mortgage Loans TDRs with Sub Defaults (Details) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018USD ($)contracts	Jun. 30, 2017USD ($)contracts	Jun. 30, 2018USD ($)contracts	Jun. 30, 2017USD ($)contracts
Financing Receivable, Modifications [Line Items]
Number of loans troubled debt restructurings subsequent default | contracts	4,568	5,029	10,273	10,343
Recorded investment troubled debt restructurings subsequent default | $	$ 674	$ 719	$ 1,526	$ 1,480
Single-family [Member]
Financing Receivable, Modifications [Line Items]
Number of loans troubled debt restructurings subsequent default | contracts			10,272	10,342
Recorded investment troubled debt restructurings subsequent default | $			$ 1,524	$ 1,476
Single-family [Member] | Primary [Member]
Financing Receivable, Modifications [Line Items]
Number of loans troubled debt restructurings subsequent default | contracts	3,834	4,238	8,652	8,717
Recorded investment troubled debt restructurings subsequent default | $	$ 554	$ 589	$ 1,255	$ 1,210
Single-family [Member] | Government [Member]
Financing Receivable, Modifications [Line Items]
Number of loans troubled debt restructurings subsequent default | contracts	15	25	29	44
Recorded investment troubled debt restructurings subsequent default | $	$ 2	$ 3	$ 4	$ 5
Single-family [Member] | Alt-A [Member]
Financing Receivable, Modifications [Line Items]
Number of loans troubled debt restructurings subsequent default | contracts	588	616	1,265	1,230
Recorded investment troubled debt restructurings subsequent default | $	$ 92	$ 97	$ 201	$ 193
Single-family [Member] | Other [Member]
Financing Receivable, Modifications [Line Items]
Number of loans troubled debt restructurings subsequent default | contracts	131	150	326	351
Recorded investment troubled debt restructurings subsequent default | $	$ 26	$ 30	$ 64	$ 68
Multifamily [Member]
Financing Receivable, Modifications [Line Items]
Number of loans troubled debt restructurings subsequent default | contracts			1	1
Recorded investment troubled debt restructurings subsequent default | $			$ 2	$ 4

Allowance for Loan Losses Rollf

Allowance for Loan Losses Rollforward by Segment (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Allowance for Loan Losses [Roll Forward]
Beginning balance	$ (18,734)	$ (22,129)	$ (19,084)	$ (23,465)
Benefit for loan losses	1,270	1,196	1,212	1,607
Charge-offs	732	689	1,201	1,729
Recoveries	(64)	(147)	(124)	(232)
Other	(16)	(8)	(17)	(38)
Ending balance	(16,812)	(20,399)	(16,812)	(20,399)
Single-family [Member]
Allowance for Loan Losses [Roll Forward]
Beginning balance	(18,523)	(21,938)	(18,849)	(23,283)
Benefit for loan losses	1,270	1,185	1,192	1,605
Charge-offs	731	689	1,196	1,729
Recoveries	(64)	(146)	(124)	(231)
Other	(16)	(8)	(17)	(38)
Ending balance	(16,602)	(20,218)	(16,602)	(20,218)
Multifamily [Member]
Allowance for Loan Losses [Roll Forward]
Beginning balance	(211)	(191)	(235)	(182)
Benefit for loan losses	0	11	20	2
Charge-offs	1	0	5	0
Recoveries	0	(1)	0	(1)
Ending balance	$ (210)	$ (181)	$ (210)	$ (181)

Allowance for Loan Losses and T

Allowance for Loan Losses and Total Recorded Investment in HFI Loans (Details) - USD ($) $ in Millions	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses for individually impaired loans	$ (15,921)		$ (17,289)
Allowance for loan losses for collectively reserved loans	(891)		(1,795)
Total allowance for loan losses	(16,812)	$ (18,734)	(19,084)	$ (20,399)	$ (22,129)	$ (23,465)
Recorded investment in individually impaired loans	129,545		135,781
Recorded investment in collectively reserved loans	3,079,961		3,054,194
Total recorded investment in loans	3,209,506		3,189,975
Single-family [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses for individually impaired loans	(15,882)		(17,247)
Allowance for loan losses for collectively reserved loans	(720)		(1,602)
Total allowance for loan losses	(16,602)	(18,523)	(18,849)	(20,218)	(21,938)	(23,283)
Recorded investment in individually impaired loans	128,959		135,191
Recorded investment in collectively reserved loans	2,803,080		2,787,783
Total recorded investment in loans	2,932,039		2,922,974
Multifamily [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses for individually impaired loans	(39)		(42)
Allowance for loan losses for collectively reserved loans	(171)		(193)
Total allowance for loan losses	(210)	$ (211)	(235)	$ (181)	$ (191)	$ (182)
Recorded investment in individually impaired loans	586		590
Recorded investment in collectively reserved loans	276,881		266,411
Total recorded investment in loans	$ 277,467		$ 267,001

Investments in Securities Tradi

Investments in Securities Trading 1 (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	$ 42,381	$ 34,679
Mortgage-related securities [Member]
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	6,621	5,457
Fannie Mae [Member]
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	1,696	3,876
Other agency [Member]
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	3,494	1,118
Alt-A and subprime private-label securities [Member]
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	1,430	453
CMBS [Member]
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	0	9
Mortgage revenue bonds [Member]
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	1	1
Non-mortgage-related securities [Member]
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	35,760	29,222
U.S. Treasury securities [Member]
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	35,663	29,222
Other securities [Member]
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	$ 97	$ 0

Investments in Securities Tra59

Investments in Securities Trading 2 (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Schedule of Trading Securities and Other Trading Assets [Line Items]
Net trading gains	$ 21	$ 18	$ 119	$ 86
Net trading gains (losses) recognized in the period related to securities still held at period end	$ 1	$ (7)	$ 48	$ 71

Investments in Securities Avail

Investments in Securities Available-for-sale Securities 1 (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Investments, Debt and Equity Securities [Abstract]
Gross realized gains	$ 0	$ 227	$ 363	$ 230
Total proceeds (excludes initial sale of securities from new portfolio securitizations)	$ 6	$ 799	$ 641	$ 894

Investments in Securities Ava61

Investments in Securities Available-for-sale Securities 2 (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Schedule of Available-for-sale Securities [Line Items]
Total amortized cost	$ 3,338	$ 4,058
Gross unrealized gains	423	816
Gross unrealized losses	(38)	(31)
Total fair value	3,723	4,843
Fannie Mae [Member]
Schedule of Available-for-sale Securities [Line Items]
Total amortized cost	1,866	2,044
Gross unrealized gains	72	102
Gross unrealized losses	(34)	(27)
Total fair value	1,904	2,119
Other agency [Member]
Schedule of Available-for-sale Securities [Line Items]
Total amortized cost	279	332
Gross unrealized gains	19	25
Gross unrealized losses	0	0
Total fair value	298	357
Alt-A and subprime private-label securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Total amortized cost	357	662
Gross unrealized gains	292	652
Gross unrealized losses	0	0
Total fair value	649	1,314
CMBS [Member]
Schedule of Available-for-sale Securities [Line Items]
Total amortized cost		15
Gross unrealized gains		0
Gross unrealized losses		0
Total fair value		15
Mortgage revenue bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Total amortized cost	494	655
Gross unrealized gains	16	20
Gross unrealized losses	(4)	(4)
Total fair value	506	671
Other mortgage-related securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Total amortized cost	342	350
Gross unrealized gains	24	17
Gross unrealized losses	0	0
Total fair value	$ 366	$ 367

Investments in Securities Ava62

Investments in Securities Available-for-sale Securities 3 (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Consecutive Months, Gross Unrealized Losses	$ (6)	$ (1)
Less than 12 Consecutive Months, Fair Value	219	134
12 Consecutive Months or Longer, Gross Unrealized Losses	(32)	(30)
12 Consecutive Months or Longer, Fair Value	422	464
Fannie Mae [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Consecutive Months, Gross Unrealized Losses	(5)	(1)
Less than 12 Consecutive Months, Fair Value	190	134
12 Consecutive Months or Longer, Gross Unrealized Losses	(29)	(26)
12 Consecutive Months or Longer, Fair Value	419	461
Mortgage revenue bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Consecutive Months, Gross Unrealized Losses	(1)	0
Less than 12 Consecutive Months, Fair Value	29	0
12 Consecutive Months or Longer, Gross Unrealized Losses	(3)	(4)
12 Consecutive Months or Longer, Fair Value	$ 3	$ 3

Investments in Securities Other

Investments in Securities Other-than-temporary Impairments (Details) - USD ($) $ in Millions	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016
Available-for-sale securities [Member]
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Balance of the unrealized credit loss component of AFS debt securities held by us	$ 733	$ 729	$ 1,100	$ 1,800	$ 1,800	$ 1,900

Investments in Securities Matur

Investments in Securities Maturity Information (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Available-for-sale Securities, Debt Maturities, Single Maturity Date, Rolling Maturity
Total amortized cost	$ 3,338	$ 4,058
Total fair value	3,723	4,843
One Year or Less, Amortized Cost	6
One Year or Less, Fair Value	6
After One Year through Five Years, Amortized Cost	56
After One Year through Five Years, Fair Value	56
After Five Years through Ten Years, Amortized Cost	191
After Five Years through Ten Years, Fair Value	199
After Ten Years, Amortized Cost	3,085
After Ten Years, Fair Value	3,462
Fannie Mae [Member]
Available-for-sale Securities, Debt Maturities, Single Maturity Date, Rolling Maturity
Total amortized cost	1,866	2,044
Total fair value	1,904	2,119
One Year or Less, Amortized Cost	0
One Year or Less, Fair Value	0
After One Year through Five Years, Amortized Cost	12
After One Year through Five Years, Fair Value	12
After Five Years through Ten Years, Amortized Cost	80
After Five Years through Ten Years, Fair Value	85
After Ten Years, Amortized Cost	1,774
After Ten Years, Fair Value	1,807
Other agency [Member]
Available-for-sale Securities, Debt Maturities, Single Maturity Date, Rolling Maturity
Total amortized cost	279	332
Total fair value	298	357
One Year or Less, Amortized Cost	2
One Year or Less, Fair Value	2
After One Year through Five Years, Amortized Cost	11
After One Year through Five Years, Fair Value	11
After Five Years through Ten Years, Amortized Cost	44
After Five Years through Ten Years, Fair Value	47
After Ten Years, Amortized Cost	222
After Ten Years, Fair Value	238
Alt-A and subprime private-label securities [Member]
Available-for-sale Securities, Debt Maturities, Single Maturity Date, Rolling Maturity
Total amortized cost	357	662
Total fair value	649	1,314
One Year or Less, Amortized Cost	0
One Year or Less, Fair Value	0
After One Year through Five Years, Amortized Cost	0
After One Year through Five Years, Fair Value	0
After Five Years through Ten Years, Amortized Cost	0
After Five Years through Ten Years, Fair Value	0
After Ten Years, Amortized Cost	357
After Ten Years, Fair Value	649
CMBS [Member]
Available-for-sale Securities, Debt Maturities, Single Maturity Date, Rolling Maturity
Total amortized cost		15
Total fair value		15
Mortgage revenue bonds [Member]
Available-for-sale Securities, Debt Maturities, Single Maturity Date, Rolling Maturity
Total amortized cost	494	655
Total fair value	506	671
One Year or Less, Amortized Cost	4
One Year or Less, Fair Value	4
After One Year through Five Years, Amortized Cost	33
After One Year through Five Years, Fair Value	33
After Five Years through Ten Years, Amortized Cost	61
After Five Years through Ten Years, Fair Value	61
After Ten Years, Amortized Cost	396
After Ten Years, Fair Value	408
Other mortgage-related securities [Member]
Available-for-sale Securities, Debt Maturities, Single Maturity Date, Rolling Maturity
Total amortized cost	342	350
Total fair value	366	$ 367
One Year or Less, Amortized Cost	0
One Year or Less, Fair Value	0
After One Year through Five Years, Amortized Cost	0
After One Year through Five Years, Fair Value	0
After Five Years through Ten Years, Amortized Cost	6
After Five Years through Ten Years, Fair Value	6
After Ten Years, Amortized Cost	336
After Ten Years, Fair Value	$ 360

Financial Guarantees Financial

Financial Guarantees Financial Guarantees and Maximum Recovery (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Financial Guarantees and Maximum Recovery [Line Items]
Maximum Exposure	$ 21,504	$ 25,141
Guaranty Obligation	163	258
Maximum Recovery	9,374	9,744
Unconsolidated VIEs [Member] | Unconsolidated Fannie Mae MBS [Member]
Financial Guarantees and Maximum Recovery [Line Items]
Maximum Exposure	7,680	10,876
Guaranty Obligation	30	127
Maximum Recovery	7,054	7,340
Unconsolidated VIEs [Member] | Other guaranty arrangements [Member]
Financial Guarantees and Maximum Recovery [Line Items]
Maximum Exposure	13,824	14,265
Guaranty Obligation	133	131
Maximum Recovery	$ 2,320	$ 2,404
Minimum [Member]
Financial Guarantees and Maximum Recovery [Line Items]
Contractual terms of our guarantees	1 day
Maximum [Member]
Financial Guarantees and Maximum Recovery [Line Items]
Contractual terms of our guarantees	34 years

Short-Term and Long-Term Debt S

Short-Term and Long-Term Debt Short-Term Debt (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Short-Term Debt [Line Items]
Short-term debt, outstanding	$ 26,065	$ 33,756
Short-term debt, weighted-average interest rate	1.86%	1.18%
Intraday line of credit [Member]
Short-Term Debt [Line Items]
Line of credit maximum borrowing capacity	$ 15,000	$ 15,000
Consolidated Trusts [Member]
Short-Term Debt [Line Items]
Short-term debt, outstanding	$ 339	$ 379
Short-term debt, weighted-average interest rate	1.88%	1.11%
Fannie Mae [Member]
Short-Term Debt [Line Items]
Short-term debt, outstanding	$ 25,726	$ 33,377
Short-term debt, weighted-average interest rate	1.86%	1.18%

Short-Term and Long-Term Debt L

Short-Term and Long-Term Debt Long-Term Debt (Details) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Long-Term Debt [Line Items]
Long-term debt, outstanding	$ 3,311,424	$ 3,296,298
Long-term debt, weighted-average interest rate	2.83%	2.77%
Consolidated Trusts [Member]
Long-Term Debt [Line Items]
Long-term debt, outstanding	$ 3,086,460	$ 3,052,923
Long-term debt, weighted-average interest rate	2.84%	2.80%
Fannie Mae [Member]
Long-Term Debt [Line Items]
Long-term debt, outstanding	$ 224,964	$ 243,375
Long-term debt, weighted-average interest rate	2.66%	2.40%
Unamortized discounts and premiums, other cost basis adjustments and fair value adjustments	$ 517	$ 752
Fannie Mae [Member] | Minimum [Member]
Long-Term Debt [Line Items]
Medium-term notes original contractual maturity	1 year	1 year
Long-term debt original contractual maturity greater than 10 years	10 years	10 years
Fannie Mae [Member] | Maximum [Member]
Long-Term Debt [Line Items]
Medium-term notes original contractual maturity	10 years	10 years
Fannie Mae [Member] | Senior Fixed [Member]
Long-Term Debt [Line Items]
Long-term debt, outstanding	$ 193,425	$ 206,863
Long-term debt, weighted-average interest rate	2.06%	1.95%
Fannie Mae [Member] | Senior fixed benchmark notes and bonds [Member]
Long-Term Debt [Line Items]
Long-term debt, outstanding	$ 116,563	$ 123,541
Long-term debt, weighted-average interest rate	2.28%	2.11%
Fannie Mae [Member] | Senior fixed medium-term notes [Member]
Long-Term Debt [Line Items]
Long-term debt, outstanding	$ 69,986	$ 75,901
Long-term debt, weighted-average interest rate	1.46%	1.41%
Fannie Mae [Member] | Senior fixed other debt [Member]
Long-Term Debt [Line Items]
Long-term debt, outstanding	$ 6,876	$ 7,421
Long-term debt, weighted-average interest rate	4.66%	4.84%
Fannie Mae [Member] | Senior floating [Member]
Long-Term Debt [Line Items]
Long-term debt, outstanding	$ 26,118	$ 31,328
Long-term debt, weighted-average interest rate	5.54%	4.14%
Fannie Mae [Member] | Senior floating medium-term notes [Member]
Long-Term Debt [Line Items]
Long-term debt, outstanding	$ 1,175	$ 8,425
Long-term debt, weighted-average interest rate	1.86%	1.36%
Fannie Mae [Member] | Senior floating Connecticut Avenue Securities [Member]
Long-Term Debt [Line Items]
Long-term debt, outstanding	$ 24,589	$ 22,527
Long-term debt, weighted-average interest rate	5.66%	5.18%
Fannie Mae [Member] | Senior floating other debt [Member]
Long-Term Debt [Line Items]
Long-term debt, outstanding	$ 354	$ 376
Long-term debt, weighted-average interest rate	9.00%	6.36%
Fannie Mae [Member] | Subordinated debentures [Member]
Long-Term Debt [Line Items]
Long-term debt, outstanding	$ 5,357	$ 5,106
Long-term debt, weighted-average interest rate	9.96%	9.93%
Fannie Mae [Member] | Secured borrowings [Member]
Long-Term Debt [Line Items]
Long-term debt, outstanding	$ 64	$ 78
Long-term debt, weighted-average interest rate	1.66%	1.70%

Derivative Instruments Derivati

Derivative Instruments Derivatives 1 - Notional and FV Position (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Asset Derivatives [Abstract]
Notional amount	$ 329,466	$ 178,138
Derivative asset, estimated fair value	372	171
Netting adjustment	(2,608)	(4,272)
Liability Derivatives [Abstract]
Notional amount	238,457	338,089
Derivative liability, estimated fair value	(604)	(328)
Netting adjustment	2,756	4,979
Table Footnote [Abstract]
Cash collateral posted for derivative instruments	742	1,400
Cash collateral received for derivative instruments	594	649
Risk Management Derivatives
Asset Derivatives [Abstract]
Notional amount	237,307	108,750
Derivative asset, estimated fair value	2,274	3,476
Accrued interest receivable (payable)	418	835
Netting adjustment	(2,608)	(4,272)
Total net risk management derivatives	84	39
Liability Derivatives [Abstract]
Notional amount	91,860	229,864
Derivative liability, estimated fair value	(2,368)	(4,265)
Accrued interest receivable (payable)	(438)	(814)
Netting adjustment	2,756	4,979
Total net risk management derivatives	(50)	(100)
Mortgage commitment derivatives
Asset Derivatives [Abstract]
Notional amount	92,159	69,388
Derivative asset, estimated fair value	288	132
Netting adjustment	0	0
Liability Derivatives [Abstract]
Notional amount	146,597	108,225
Derivative liability, estimated fair value	(554)	(228)
Netting adjustment	0	0
Pay-fixed Swap
Asset Derivatives [Abstract]
Notional amount	93,391	52,732
Derivative asset, estimated fair value	723	772
Liability Derivatives [Abstract]
Notional amount	19,845	70,211
Derivative liability, estimated fair value	(674)	(2,120)
Receive-fixed Swap
Asset Derivatives [Abstract]
Notional amount	106,673	31,671
Derivative asset, estimated fair value	1,123	2,391
Liability Derivatives [Abstract]
Notional amount	63,209	138,852
Derivative liability, estimated fair value	(1,296)	(1,764)
Basis Swap
Asset Derivatives [Abstract]
Notional amount	273	873
Derivative asset, estimated fair value	98	124
Liability Derivatives [Abstract]
Notional amount	600	0
Derivative liability, estimated fair value	0	0
Foreign Currency Swap
Asset Derivatives [Abstract]
Notional amount	229	234
Derivative asset, estimated fair value	37	59
Liability Derivatives [Abstract]
Notional amount	231	236
Derivative liability, estimated fair value	(59)	(56)
Pay-fixed Swaption
Asset Derivatives [Abstract]
Notional amount	11,525	9,750
Derivative asset, estimated fair value	254	95
Liability Derivatives [Abstract]
Notional amount	600	4,000
Derivative liability, estimated fair value	(2)	(20)
Receive-fixed Swaption
Asset Derivatives [Abstract]
Notional amount	500	250
Derivative asset, estimated fair value	19	13
Liability Derivatives [Abstract]
Notional amount	7,375	9,250
Derivative liability, estimated fair value	(336)	(304)
Other
Asset Derivatives [Abstract]
Notional amount	24,716	13,240
Derivative asset, estimated fair value	20	22
Liability Derivatives [Abstract]
Notional amount	0	7,315
Derivative liability, estimated fair value	(1)	(1)
Mortgage commitments to purchase whole loans
Asset Derivatives [Abstract]
Notional amount	6,025	4,143
Derivative asset, estimated fair value	20	9
Liability Derivatives [Abstract]
Notional amount	1,506	1,570
Derivative liability, estimated fair value	(1)	(2)
Forward contracts to purchase mortgage-related securities
Asset Derivatives [Abstract]
Notional amount	80,636	45,925
Derivative asset, estimated fair value	263	108
Liability Derivatives [Abstract]
Notional amount	11,060	21,099
Derivative liability, estimated fair value	(16)	(21)
Forward contracts to sell mortgage-related securities
Asset Derivatives [Abstract]
Notional amount	5,498	19,320
Derivative asset, estimated fair value	5	15
Liability Derivatives [Abstract]
Notional amount	134,031	85,556
Derivative liability, estimated fair value	$ (537)	$ (205)

Derivative Instruments Deriva69

Derivative Instruments Derivatives 2 - FV Gains and Losses (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Derivative Instruments, Gain (Loss) [Line Items]
Derivative fair value gains (losses), net	$ (38)	$ (494)	$ 825	$ (462)
Net accrual of periodic settlements	5,377	5,002	10,609	10,348
Pay-fixed Swap
Derivative Instruments, Gain (Loss) [Line Items]
Derivative fair value gains (losses), net	967	(691)	3,750	0
Receive-fixed Swap
Derivative Instruments, Gain (Loss) [Line Items]
Derivative fair value gains (losses), net	(597)	639	(2,984)	322
Basis Swap
Derivative Instruments, Gain (Loss) [Line Items]
Derivative fair value gains (losses), net	(3)	16	(26)	23
Foreign Currency Swap
Derivative Instruments, Gain (Loss) [Line Items]
Derivative fair value gains (losses), net	(41)	11	(25)	23
Pay-fixed Swaption
Derivative Instruments, Gain (Loss) [Line Items]
Derivative fair value gains (losses), net	36	(48)	165	(48)
Receive-fixed Swaption
Derivative Instruments, Gain (Loss) [Line Items]
Derivative fair value gains (losses), net	(22)	(8)	(38)	(26)
Other
Derivative Instruments, Gain (Loss) [Line Items]
Derivative fair value gains (losses), net	(16)	3	(4)	(5)
Risk Management Derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Derivative fair value gains (losses), net	38	(302)	337	(190)
Net accrual of periodic settlements	(286)	(224)	(501)	(479)
Mortgage commitment derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Derivative fair value gains (losses), net	$ (76)	$ (192)	$ 488	$ (272)

Segment Reporting Narrative (De

Segment Reporting Narrative (Details)	6 Months Ended
	Jun. 30, 2018segments
Segment Reporting [Abstract]
Number of Reportable Segments	2

Segment Reporting (Details)

Segment Reporting (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Segment Reporting Information [Line Items]
Net interest income	$ 5,377	$ 5,002	$ 10,609	$ 10,348
Fee and other income	239	353	559	602
Net revenues	5,616	5,355	11,168	10,950
Investment gains (losses), net	277	385	527	376
Fair value gains (losses), net	229	(691)	1,274	(731)
Administrative expenses	(755)	(686)	(1,505)	(1,370)
Benefit (provision) for credit losses	1,296	1,267	1,513	1,663
Foreclosed property income (expense)	(139)	(34)	(301)	(251)
Total credit-related income (expense)	1,157	1,233	1,212	1,412
Temporary Payroll Tax Cut Continuation Act of 2011 (“TCCA”) fees	(565)	(518)	(1,122)	(1,021)
Other expenses, net	(366)	(291)	(569)	(673)
Income before federal income taxes	5,593	4,787	10,985	8,943
Provision for federal income taxes	(1,136)	(1,587)	(2,267)	(2,970)
Net income	4,457	3,200	8,718	5,973
US Treasury [Member]
Segment Reporting Information [Line Items]
Temporary Payroll Tax Cut Continuation Act of 2011 (“TCCA”) fees	(565)	(518)	(1,122)	(1,021)
Business Segments [Member] | Single-family [Member]
Segment Reporting Information [Line Items]
Net interest income	4,723	4,366	9,284	9,122
Fee and other income	69	111	227	187
Net revenues	4,792	4,477	9,511	9,309
Investment gains (losses), net	252	321	494	271
Fair value gains (losses), net	278	(685)	1,312	(697)
Administrative expenses	(649)	(600)	(1,292)	(1,201)
Benefit (provision) for credit losses	1,295	1,255	1,491	1,655
Foreclosed property income (expense)	(136)	(32)	(298)	(248)
Total credit-related income (expense)	1,159	1,223	1,193	1,407
Other expenses, net	(270)	(155)	(402)	(411)
Income before federal income taxes	4,997	4,063	9,694	7,657
Provision for federal income taxes	(1,044)	(1,401)	(2,060)	(2,653)
Net income	3,953	2,662	7,634	5,004
Business Segments [Member] | Single-family [Member] | US Treasury [Member]
Segment Reporting Information [Line Items]
Temporary Payroll Tax Cut Continuation Act of 2011 (“TCCA”) fees	(565)	(518)	(1,122)	(1,021)
Business Segments [Member] | Multifamily [Member]
Segment Reporting Information [Line Items]
Net interest income	654	636	1,325	1,226
Fee and other income	170	242	332	415
Net revenues	824	878	1,657	1,641
Investment gains (losses), net	25	64	33	105
Fair value gains (losses), net	(49)	(6)	(38)	(34)
Administrative expenses	(106)	(86)	(213)	(169)
Benefit (provision) for credit losses	1	12	22	8
Foreclosed property income (expense)	(3)	(2)	(3)	(3)
Total credit-related income (expense)	(2)	10	19	5
Other expenses, net	(96)	(136)	(167)	(262)
Income before federal income taxes	596	724	1,291	1,286
Provision for federal income taxes	(92)	(186)	(207)	(317)
Net income	$ 504	$ 538	$ 1,084	$ 969

Equity Activity in OCI (Details

Equity Activity in OCI (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Equity [Abstract]
Net income	$ 4,457	$ 3,200	$ 8,718	$ 5,973
Other comprehensive income (loss), net of tax effect:
Changes in net unrealized gains (losses) on AFS securities (net of tax of $1 and $6, respectively, for the three months ended and net of tax of $14 and $11, respectively, for the six months ended)	4	11	(53)	20
Reclassification adjustments for gains on AFS securities and other-than-temporary impairment (“OTTI”) recognized in net income (net of tax of $0 and $50, respectively, for the three months ended and $70 and $51, respectively, for the six months ended)	0	(92)	(263)	(93)
Other	(2)	(2)	(5)	(4)
Total other comprehensive income (loss)	2	(83)	(321)	(77)
Total comprehensive income	4,459	3,117	8,397	5,896
Other Comprehensive Income (Loss), Tax, Parenthetical Disclosures [Abstract]
Changes in net unrealized gains (losses) on AFS securities (net of tax of $1 and $6, respectively, for the three months ended and net of tax of $14 and $11, respectively, for the six months ended )	1	6	(14)	11
Reclassification adjustments for gains on AFS securities and other-than-temporary impairment (“OTTI”) recognized in net income (net of tax of $0 and $50, respectively, for the three months ended and $70 and $51, respectively, for the six months ended)	$ 0	$ (50)	$ (70)	$ (51)

Equity AOCI (Details)

Equity AOCI (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Equity [Abstract]
Net unrealized gains on AFS securities for which we have not recorded OTTI	$ 50	$ 87
Net unrealized gains on AFS securities for which we have recorded OTTI	254	423
Other	45	43
Accumulated other comprehensive income	$ 349	$ 553

Equity Changes in AOCI (Details

Equity Changes in AOCI (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Increase (Decrease) in Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	$ 3,900		$ (3,686)
Total other comprehensive income (loss)	2	$ (83)	(321)	$ (77)
Ending balance	7,459		$ 7,459		$ (3,686)
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent			21.00%		35.00%
Accumulated net unrealized investment gain (loss), AFS securities [Member]
Increase (Decrease) in Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	300	724	$ 510	716	$ 716
Reclassification of accumulated other comprehensive income to retained earnings resulting from the enactment of the Tax Cuts and Jobs Act	0	0	110	0
Other comprehensive income (loss) before reclassifications	4	11	(53)	20
Amounts reclassified from other comprehensive income (loss)	0	(92)	(263)	(93)
Total other comprehensive income (loss)	4	(81)	(316)	(73)
Ending balance	304	643	304	643	510
Accumulated other comprehensive income (loss), Other [Member]
Increase (Decrease) in Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	47	41	43	43	43
Reclassification of accumulated other comprehensive income to retained earnings resulting from the enactment of the Tax Cuts and Jobs Act	0	0	7	0
Other comprehensive income (loss) before reclassifications	0	0	0	0
Amounts reclassified from other comprehensive income (loss)	(2)	(2)	(5)	(4)
Total other comprehensive income (loss)	(2)	(2)	(5)	(4)
Ending balance	45	39	45	39	43
Accumulated other comprehensive income [Member]
Increase (Decrease) in Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	347	765	553	759	759
Reclassification of accumulated other comprehensive income to retained earnings resulting from the enactment of the Tax Cuts and Jobs Act	0	0	117	0
Other comprehensive income (loss) before reclassifications	4	11	(53)	20
Amounts reclassified from other comprehensive income (loss)	(2)	(94)	(268)	(97)
Total other comprehensive income (loss)	2	(83)	(321)	(77)
Ending balance	$ 349	$ 682	$ 349	$ 682	$ 553

Concentrations of Credit Risk S

Concentrations of Credit Risk SF Risk Characteristics (Details) - Single-family [Member]	6 Months Ended	12 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Guaranty Book of Business [Member] | Conventional Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
30 days delinquent (percentage of book of business)	1.14%	1.42%
60 days delinquent (percentage of book of business)	0.29%	0.43%
Seriously delinquent (percentage of book of business)	0.90%	1.15%
30 days delinquent (percentage of conventional loans)	1.34%	1.63%
60 days delinquent (percentage of conventional loans)	0.34%	0.50%
Seriously delinquent (percentage of conventional loans)	0.97%	1.24%
Percentage of loans with detailed loan level information	99.00%	99.00%
Guaranty Book of Business [Member] | Conventional Loan [Member] | California
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of book of business	19.00%	19.00%
Seriously delinquent (percentage of conventional loans)	0.36%	0.42%
Guaranty Book of Business [Member] | Conventional Loan [Member] | Florida
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of book of business	6.00%	6.00%
Seriously delinquent (percentage of conventional loans)	2.51%	3.71%
Guaranty Book of Business [Member] | Conventional Loan [Member] | New Jersey
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of book of business	4.00%	4.00%
Seriously delinquent (percentage of conventional loans)	1.68%	2.15%
Guaranty Book of Business [Member] | Conventional Loan [Member] | New York
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of book of business	5.00%	5.00%
Seriously delinquent (percentage of conventional loans)	1.66%	2.02%
Guaranty Book of Business [Member] | Conventional Loan [Member] | All other states
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of book of business	66.00%	66.00%
Seriously delinquent (percentage of conventional loans)	0.88%	1.09%
Guaranty Book of Business [Member] | Conventional Loan [Member] | Estimated mark-to-market loan-to-value ratio greater than 100%
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of book of business	1.00%	1.00%
Seriously delinquent (percentage of conventional loans)	11.41%	11.70%
Guaranty Book of Business [Member] | Conventional Loan [Member] | Alt-A [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of book of business	2.00%	2.00%
Seriously delinquent (percentage of conventional loans)	4.21%	4.95%
Guaranty Book of Business [Member] | Conventional Loan [Member] | 2004 and prior
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of book of business	3.00%	4.00%
Seriously delinquent (percentage of conventional loans)	3.00%	3.28%
Guaranty Book of Business [Member] | Conventional Loan [Member] | 2005-2008
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of book of business	6.00%	6.00%
Seriously delinquent (percentage of conventional loans)	5.54%	6.55%
Guaranty Book of Business [Member] | Conventional Loan [Member] | 2009-2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of book of business	91.00%	90.00%
Seriously delinquent (percentage of conventional loans)	0.41%	0.53%
Minimum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Serious delinquency, days past due	90 days	90 days

Concentrations of Credit Risk M

Concentrations of Credit Risk MF Risk Characteristics (Details) - Multifamily [Member]	6 Months Ended	12 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Minimum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Serious delinquency, days past due	60 days	60 days
Current debt service coverage ratio reporting lag	3 months	3 months
Maximum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current debt service coverage ratio (higher risk loans)	1	1
Serious delinquency, days past due	89 days	89 days
Current debt service coverage ratio reporting lag	6 months	6 months
Guaranty Book of Business [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
30 days delinquent (percentage of book of business)	0.01%	0.03%
Seriously delinquent (percentage of book of business)	0.10%	0.11%
Percentage of loans with detailed loan level information	99.00%	99.00%
Guaranty Book of Business [Member] | Original LTV ratio greater than 80% [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of book of business	1.00%	2.00%
Loans seriously delinquent, percentage by unpaid principal balance	0.19%	0.21%
Guaranty Book of Business [Member] | Original LTV ratio less than or equal to 80% [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of book of business	99.00%	98.00%
Loans seriously delinquent, percentage by unpaid principal balance	0.10%	0.11%
Guaranty Book of Business [Member] | Current DSCR less than 100% [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of book of business	2.00%	2.00%
Loans seriously delinquent, percentage by unpaid principal balance	3.25%	1.96%

Concentrations of Credit Risk O

Concentrations of Credit Risk Other Concentrations (Details) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2018USD ($)insurers	Dec. 31, 2017USD ($)
Concentration Risk [Line Items]
Estimated benefit included in total loss reserves	$ 833	$ 989
Receivable from claims on insured, defaulted loans excluding government insured loans	792	858
Allowance for mortgage insurance receivable	568	593
Mortgage Sellers and Servicers [Member]
Concentration Risk [Line Items]
Receivable from claims on insured, defaulted loans excluding government insured loans	$ 47	75
PMI Mortgage Insurance Company [Member]
Concentration Risk [Line Items]
Mortgage insurance coverage risk in force percentage to be paid in cash	72.50%
Mortgage insurance coverage risk in force percentage to be deferred	27.50%
Triad Guaranty Insurance Corporation 1 [Member]
Concentration Risk [Line Items]
Mortgage insurance coverage risk in force percentage to be paid in cash	75.00%
Mortgage insurance coverage risk in force percentage to be deferred	25.00%
Single-family [Member]
Concentration Risk [Line Items]
Number of mortgage Insurers publicly disclosed credit quality deterioration | insurers	3
Single-family [Member] | Guaranty Book of Business [Member]
Concentration Risk [Line Items]
Mortgage insurance coverage risk in force	$ 144,455	$ 138,460
Mortgage insurance coverage risk in force as percentage	5.00%	5.00%
Primary mortgage insurance coverage risk in force	$ 144,023	$ 137,941
Pool mortgage insurance coverage risk in force	$ 432	$ 519
Single-family [Member] | Guaranty Book of Business [Member] | Credit Concentration Risk [Member] | Group of Largest Mortgage Servicers including Affiliates [Member]
Concentration Risk [Line Items]
Percentage of Total Risk in Force Mortgage Insurance Coverage	55.00%	55.00%
Single-family [Member] | Guaranty Book of Business [Member] | Credit Concentration Risk [Member] | Group of Largest Mortgage Servicers including Affiliates [Member] | Non-Depository Servicer [Member]
Concentration Risk [Line Items]
Percentage of Total Risk in Force Mortgage Insurance Coverage	21.00%	20.00%
Single-family [Member] | Guaranty Book of Business [Member] | Credit Concentration Risk [Member] | Wells Fargo Bank N.A. [Member] | Depository Servicer [Member]
Concentration Risk [Line Items]
Percentage of Total Risk in Force Mortgage Insurance Coverage	18.00%	18.00%
Single-family [Member] | Guaranty Book of Business [Member] | Credit Concentration Risk [Member] | Other Servicers [Member] | Depository Servicer [Member]
Concentration Risk [Line Items]
Percentage of Total Risk in Force Mortgage Insurance Coverage	16.00%	17.00%
Single-family [Member] | Guaranty Book of Business [Member] | Insurance Service Provider Concentration Risk [Member]
Concentration Risk [Line Items]
Percentage of Total Risk in Force Mortgage Insurance Coverage	100.00%	100.00%
Single-family [Member] | Guaranty Book of Business [Member] | Insurance Service Provider Concentration Risk [Member] | Arch Capital Group Ltd. [Member]
Concentration Risk [Line Items]
Percentage of Total Risk in Force Mortgage Insurance Coverage	25.00%	25.00%
Single-family [Member] | Guaranty Book of Business [Member] | Insurance Service Provider Concentration Risk [Member] | Radian Guaranty, Inc [Member]
Concentration Risk [Line Items]
Percentage of Total Risk in Force Mortgage Insurance Coverage	21.00%	21.00%
Single-family [Member] | Guaranty Book of Business [Member] | Insurance Service Provider Concentration Risk [Member] | Mortgage Guaranty Insurance Corp. [Member]
Concentration Risk [Line Items]
Percentage of Total Risk in Force Mortgage Insurance Coverage	19.00%	19.00%
Single-family [Member] | Guaranty Book of Business [Member] | Insurance Service Provider Concentration Risk [Member] | Genworth Mortgage Insurance Corp. [Member]
Concentration Risk [Line Items]
Percentage of Total Risk in Force Mortgage Insurance Coverage	15.00%	15.00%
Single-family [Member] | Guaranty Book of Business [Member] | Insurance Service Provider Concentration Risk [Member] | Essent Guaranty, Inc [Member]
Concentration Risk [Line Items]
Percentage of Total Risk in Force Mortgage Insurance Coverage	11.00%	11.00%
Single-family [Member] | Guaranty Book of Business [Member] | Insurance Service Provider Concentration Risk [Member] | Other counterparties [Member]
Concentration Risk [Line Items]
Percentage of Total Risk in Force Mortgage Insurance Coverage	9.00%	9.00%
Single-family [Member] | Guaranty Book of Business [Member] | Insurance Service Provider with Credit Quality Deterioration Concentration Risk [Member]
Concentration Risk [Line Items]
Percentage of Total Risk in Force Mortgage Insurance Coverage	4.00%
Mortgage insurance coverage risk in force for insurers with credit quality deterioration	$ 5,400
Multifamily [Member] | Guaranty Book of Business [Member] | Credit Concentration Risk [Member] | Group of Largest Mortgage Servicers including Affiliates [Member]
Concentration Risk [Line Items]
Percentage of Total Risk in Force Mortgage Insurance Coverage	48.00%	48.00%
Multifamily [Member] | Guaranty Book of Business [Member] | Credit Concentration Risk [Member] | Wells Fargo Bank N.A. [Member]
Concentration Risk [Line Items]
Percentage of Total Risk in Force Mortgage Insurance Coverage	14.00%	14.00%
Multifamily [Member] | Guaranty Book of Business [Member] | Credit Concentration Risk [Member] | Walker & Dunlop, LLC [Member]
Concentration Risk [Line Items]
Percentage of Total Risk in Force Mortgage Insurance Coverage	11.00%	12.00%
Multifamily [Member] | Guaranty Book of Business [Member] | Credit Concentration Risk [Member] | Other Servicers [Member]
Concentration Risk [Line Items]
Percentage of Total Risk in Force Mortgage Insurance Coverage	23.00%	22.00%

Netting Arrangements (Details)

Netting Arrangements (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Assets:
Derivative assets, gross amount	$ 2,960	$ 4,422
Derivative assets, gross amount offset	(2,608)	(4,272)
Derivative assets, net amount presented in our condensed consolidated balance sheets	352	150
Derivative assets, under master netting arrangements, amounts not offset in our condensed consolidated balance sheets, financial instruments	(196)	(117)
Derivative assets, under master netting arrangements, amounts not offset in our condensed consolidated balance sheets, collateral	0	(1)
Derivative assets, net amount	156	32
Securities purchased under agreements to resell or similar arrangements, gross amount	27,350	44,670
Securities purchased under agreements to resell or similar arrangements, gross amount offset	0	0
Securities Purchased under Agreements to Resell, Not Subject to Master Netting Arrangement	27,350	44,670
Securities purchased under agreements to resell or similar arrangements, under master netting arrangements, amounts not offset in our condensed consolidated balance sheets, financial instruments	0	0
Securities purchased under agreements to resell or similar arrangements, under master netting arrangements, amounts not offset in our condensed consolidated balance sheets, collateral	(27,350)	(44,670)
Securities purchased under agreements to resell or similar arrangements, net amount	0	0
Total assets, gross amount	30,310	49,092
Total assets, gross amount offset	(2,608)	(4,272)
Total assets, net amount presented in our condensed consolidated balance sheets	27,702	44,820
Total assets, under master netting arrangements, amounts not offset in our condensed consolidated balance sheets, financial instruments	(196)	(117)
Total assets, under master netting arrangements, amounts not offset in our condensed consolidated balance sheets, collateral	(27,350)	(44,671)
Total assets, net amount	156	32
Liabilities:
Derivative liabilities, gross amount	(3,359)	(5,306)
Derivative liabilities, gross amount offset	2,756	4,979
Derivative liabilities, net amount presented in our condensed consolidated balance sheets	(603)	(327)
Derivative liabilities, under master netting arrangements, amounts not offset in our condensed consolidated balance sheets, financial instruments	196	117
Derivative liabilities, under master netting arrangements, amounts not offset in our condensed consolidated balance sheets, collateral	326	104
Derivative liabilities, net amount	(81)	(106)
Total liabilities, gross amount	(3,359)	(5,306)
Total liabilities, gross amount offset	2,756	4,979
Total liabilities, net amount presented in our condensed consolidated balance sheets	(603)	(327)
Total liabilities, under master netting arrangements, amounts not offset in our condensed consolidated balance sheets, financial instruments	196	117
Total liabilities, under master netting arrangements, amounts not offset in our condensed consolidated balance sheets, collateral	326	104
Total liabilities, net amount	(81)	(106)
Risk Management Derivatives
Assets:
Derivative assets, gross amount offset	(2,608)	(4,272)
Liabilities:
Derivative liabilities, gross amount offset	2,756	4,979
Mortgage commitment derivatives
Assets:
Derivative assets, gross amount	288	132
Derivative assets, gross amount offset	0	0
Derivative assets, net amount presented in our condensed consolidated balance sheets	288	132
Derivative assets, under master netting arrangements, amounts not offset in our condensed consolidated balance sheets, financial instruments	(196)	(117)
Derivative assets, under master netting arrangements, amounts not offset in our condensed consolidated balance sheets, collateral	0	(1)
Derivative assets, net amount	92	14
Liabilities:
Derivative liabilities, gross amount	(554)	(228)
Derivative liabilities, gross amount offset	0	0
Derivative liabilities, net amount presented in our condensed consolidated balance sheets	(554)	(228)
Derivative liabilities, under master netting arrangements, amounts not offset in our condensed consolidated balance sheets, financial instruments	196	117
Derivative liabilities, under master netting arrangements, amounts not offset in our condensed consolidated balance sheets, collateral	325	93
Derivative liabilities, net amount	(33)	(18)
Over the Counter [Member] | Risk Management Derivatives
Assets:
Derivative assets, gross amount	2,672	2,479
Derivative assets, gross amount offset	(2,630)	(2,464)
Derivative assets, net amount presented in our condensed consolidated balance sheets	42	15
Derivative assets, under master netting arrangements, amounts not offset in our condensed consolidated balance sheets, financial instruments	0	0
Derivative assets, under master netting arrangements, amounts not offset in our condensed consolidated balance sheets, collateral	0	0
Derivative assets, net amount	42	15
Liabilities:
Derivative liabilities, gross amount	(2,805)	(3,045)
Derivative liabilities, gross amount offset	2,757	2,957
Derivative liabilities, net amount presented in our condensed consolidated balance sheets	(48)	(88)
Derivative liabilities, under master netting arrangements, amounts not offset in our condensed consolidated balance sheets, financial instruments	0	0
Derivative liabilities, under master netting arrangements, amounts not offset in our condensed consolidated balance sheets, collateral	0	0
Derivative liabilities, net amount	(48)	(88)
Exchange Cleared [Member] | Risk Management Derivatives
Assets:
Derivative assets, gross amount	0	1,811
Derivative assets, gross amount offset	22	(1,808)
Derivative assets, net amount presented in our condensed consolidated balance sheets	22	3
Derivative assets, under master netting arrangements, amounts not offset in our condensed consolidated balance sheets, financial instruments	0	0
Derivative assets, under master netting arrangements, amounts not offset in our condensed consolidated balance sheets, collateral	0	0
Derivative assets, net amount	22	3
Liabilities:
Derivative liabilities, gross amount	0	(2,033)
Derivative liabilities, gross amount offset	(1)	2,022
Derivative liabilities, net amount presented in our condensed consolidated balance sheets	(1)	(11)
Derivative liabilities, under master netting arrangements, amounts not offset in our condensed consolidated balance sheets, financial instruments	0	0
Derivative liabilities, under master netting arrangements, amounts not offset in our condensed consolidated balance sheets, collateral	1	11
Derivative liabilities, net amount	$ 0	$ 0

Netting Arrangements Narratives

Netting Arrangements Narratives (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Derivative [Line Items]
Fair value of non-cash collateral we pledged	$ 2,200	$ 747
Fair value of non-cash collateral received	27,400	44,700
Fair value of non-cash collateral received that can be resold or repledged	24,900	42,500
Fair value of securities received as collateral that have been resold or repledge	0	0
Derivative assets not subject to enforceable master netting arrangements	20	21
Derivative liabilities not subject to enforceable master netting arrangements	(1)	(1)
Cash and Cash Equivalents [Member]
Derivative [Line Items]
Securities purchased under agreements to resell	$ 11,100	$ 25,200

Fair Value Levels Hierarchy (De

Fair Value Levels Hierarchy (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Assets [Abstract]
Mortgage loans held for investment, at fair value	$ 9,628	$ 10,596
Other assets [Abstract]
Derivative assets, gross amount offset	(2,608)	(4,272)
Other liabilities [Abstract]
Derivative liabilities, gross amount offset	(2,756)	(4,979)
Mortgage commitment derivatives
Other assets [Abstract]
Derivative assets, gross amount offset	0	0
Other liabilities [Abstract]
Derivative liabilities, gross amount offset	0	0
Fannie Mae [Member]
Liabilities [Abstract]
Long-term debt, fair value	7,558	8,186
Consolidated Trusts [Member]
Liabilities [Abstract]
Long-term debt, fair value	26,675	30,493
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Assets [Abstract]
Trading securities	35,663	29,222
Available-for-sale securities	0	0
Mortgage loans held for investment, at fair value	0	0
Other assets [Abstract]
Derivatives assets at fair value	0	0
Total assets at fair value	73,342	64,282
Other liabilities [Abstract]
Derivative liabilities at fair value	0	0
Total liabilities at fair value	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Fannie Mae [Member]
Liabilities [Abstract]
Long-term debt, fair value	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Consolidated Trusts [Member]
Liabilities [Abstract]
Long-term debt, fair value	0	0
Significant Other Observable Inputs (Level 2) [Member]
Assets [Abstract]
Trading securities	6,638	4,256
Available-for-sale securities	2,630	3,530
Mortgage loans held for investment, at fair value	2,917,541	2,886,470
Other assets [Abstract]
Derivatives assets at fair value	2,851	4,274
Total assets at fair value	2,962,345	2,948,237
Other liabilities [Abstract]
Derivative liabilities at fair value	3,348	5,272
Total liabilities at fair value	3,231,716	3,302,681
Significant Other Observable Inputs (Level 2) [Member] | Fannie Mae [Member]
Liabilities [Abstract]
Long-term debt, fair value	228,853	249,780
Significant Other Observable Inputs (Level 2) [Member] | Consolidated Trusts [Member]
Liabilities [Abstract]
Long-term debt, fair value	2,973,785	3,014,250
Significant Unobservable Inputs (Level 3) [Member]
Assets [Abstract]
Trading securities	80	1,201
Available-for-sale securities	1,093	1,313
Mortgage loans held for investment, at fair value	231,082	315,719
Other assets [Abstract]
Derivatives assets at fair value	129	169
Total assets at fair value	246,650	324,173
Other liabilities [Abstract]
Derivative liabilities at fair value	12	35
Total liabilities at fair value	42,250	42,389
Significant Unobservable Inputs (Level 3) [Member] | Fannie Mae [Member]
Liabilities [Abstract]
Long-term debt, fair value	791	837
Significant Unobservable Inputs (Level 3) [Member] | Consolidated Trusts [Member]
Liabilities [Abstract]
Long-term debt, fair value	40,988	40,683
Recurring Fair Value Measurements [Member]
Assets [Abstract]
Cash equivalents	498
Trading securities	42,381	34,679
Available-for-sale securities	3,723	4,843
Mortgage loans held for investment, at fair value	9,628	10,596
Other assets [Abstract]
Derivatives assets at fair value	372	171
Derivative assets, gross amount offset	(2,608)	(4,272)
Total assets at fair value	56,602	50,289
Liabilities [Abstract]
Long-term debt, fair value	34,233	38,679
Other liabilities [Abstract]
Derivative liabilities at fair value	604	328
Derivative liabilities, gross amount offset	(2,756)	(4,979)
Total liabilities at fair value	34,837	39,007
Recurring Fair Value Measurements [Member] | Swaps [Member]
Other assets [Abstract]
Derivatives assets at fair value	2,399	4,181
Other liabilities [Abstract]
Derivative liabilities at fair value	2,467	4,754
Recurring Fair Value Measurements [Member] | Swaptions [Member]
Other assets [Abstract]
Derivatives assets at fair value	273	108
Other liabilities [Abstract]
Derivative liabilities at fair value	338	324
Recurring Fair Value Measurements [Member] | Other [Member]
Other assets [Abstract]
Derivatives assets at fair value	20	22
Other liabilities [Abstract]
Derivative liabilities at fair value	1	1
Recurring Fair Value Measurements [Member] | Mortgage commitment derivatives
Other assets [Abstract]
Derivatives assets at fair value	288	132
Other liabilities [Abstract]
Derivative liabilities at fair value	554	228
Recurring Fair Value Measurements [Member] | Fannie Mae [Member]
Liabilities [Abstract]
Long-term debt, fair value	7,558	8,186
Recurring Fair Value Measurements [Member] | Fannie Mae [Member] | Senior floating [Member]
Liabilities [Abstract]
Long-term debt, fair value	7,558	8,186
Recurring Fair Value Measurements [Member] | Consolidated Trusts [Member]
Liabilities [Abstract]
Long-term debt, fair value	26,675	30,493
Recurring Fair Value Measurements [Member] | Fannie Mae [Member]
Assets [Abstract]
Trading securities	1,696	3,876
Available-for-sale securities	1,904	2,119
Recurring Fair Value Measurements [Member] | Other agency [Member]
Assets [Abstract]
Trading securities	3,494	1,118
Available-for-sale securities	298	357
Recurring Fair Value Measurements [Member] | Alt-A and subprime private-label securities [Member]
Assets [Abstract]
Trading securities	1,430	453
Available-for-sale securities	649	1,314
Recurring Fair Value Measurements [Member] | CMBS [Member]
Assets [Abstract]
Trading securities		9
Available-for-sale securities		15
Recurring Fair Value Measurements [Member] | Mortgage revenue bonds [Member]
Assets [Abstract]
Trading securities	1	1
Available-for-sale securities	506	671
Recurring Fair Value Measurements [Member] | Other [Member]
Assets [Abstract]
Available-for-sale securities	366	367
Recurring Fair Value Measurements [Member] | U.S. Treasury securities [Member]
Assets [Abstract]
Trading securities	35,663	29,222
Recurring Fair Value Measurements [Member] | Other securities [Member]
Assets [Abstract]
Trading securities	97
Recurring Fair Value Measurements [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Assets [Abstract]
Cash equivalents	498
Trading securities	35,663	29,222
Available-for-sale securities	0	0
Mortgage loans held for investment, at fair value	0	0
Other assets [Abstract]
Derivatives assets at fair value	0	0
Total assets at fair value	36,161	29,222
Liabilities [Abstract]
Long-term debt, fair value	0	0
Other liabilities [Abstract]
Derivative liabilities at fair value	0	0
Total liabilities at fair value	0	0
Recurring Fair Value Measurements [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Swaps [Member]
Other assets [Abstract]
Derivatives assets at fair value	0	0
Other liabilities [Abstract]
Derivative liabilities at fair value	0	0
Recurring Fair Value Measurements [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Swaptions [Member]
Other assets [Abstract]
Derivatives assets at fair value	0	0
Other liabilities [Abstract]
Derivative liabilities at fair value	0	0
Recurring Fair Value Measurements [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Other [Member]
Other assets [Abstract]
Derivatives assets at fair value	0	0
Other liabilities [Abstract]
Derivative liabilities at fair value	0	0
Recurring Fair Value Measurements [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Mortgage commitment derivatives
Other assets [Abstract]
Derivatives assets at fair value	0	0
Other liabilities [Abstract]
Derivative liabilities at fair value	0	0
Recurring Fair Value Measurements [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Fannie Mae [Member]
Liabilities [Abstract]
Long-term debt, fair value	0	0
Recurring Fair Value Measurements [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Fannie Mae [Member] | Senior floating [Member]
Liabilities [Abstract]
Long-term debt, fair value	0	0
Recurring Fair Value Measurements [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Consolidated Trusts [Member]
Liabilities [Abstract]
Long-term debt, fair value	0	0
Recurring Fair Value Measurements [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Fannie Mae [Member]
Assets [Abstract]
Trading securities	0	0
Available-for-sale securities	0	0
Recurring Fair Value Measurements [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Other agency [Member]
Assets [Abstract]
Trading securities	0	0
Available-for-sale securities	0	0
Recurring Fair Value Measurements [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Alt-A and subprime private-label securities [Member]
Assets [Abstract]
Trading securities	0	0
Available-for-sale securities	0	0
Recurring Fair Value Measurements [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | CMBS [Member]
Assets [Abstract]
Trading securities		0
Available-for-sale securities		0
Recurring Fair Value Measurements [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Mortgage revenue bonds [Member]
Assets [Abstract]
Trading securities	0	0
Available-for-sale securities	0	0
Recurring Fair Value Measurements [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Other [Member]
Assets [Abstract]
Available-for-sale securities	0	0
Recurring Fair Value Measurements [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | U.S. Treasury securities [Member]
Assets [Abstract]
Trading securities	35,663	29,222
Recurring Fair Value Measurements [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Other securities [Member]
Assets [Abstract]
Trading securities	0
Recurring Fair Value Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member]
Assets [Abstract]
Cash equivalents	0
Trading securities	6,638	4,256
Available-for-sale securities	2,630	3,530
Mortgage loans held for investment, at fair value	8,610	9,480
Other assets [Abstract]
Derivatives assets at fair value	2,851	4,274
Total assets at fair value	20,729	21,540
Liabilities [Abstract]
Long-term debt, fair value	33,560	37,721
Other liabilities [Abstract]
Derivative liabilities at fair value	3,348	5,272
Total liabilities at fair value	36,908	42,993
Recurring Fair Value Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member] | Swaps [Member]
Other assets [Abstract]
Derivatives assets at fair value	2,291	4,035
Other liabilities [Abstract]
Derivative liabilities at fair value	2,466	4,721
Recurring Fair Value Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member] | Swaptions [Member]
Other assets [Abstract]
Derivatives assets at fair value	273	108
Other liabilities [Abstract]
Derivative liabilities at fair value	338	324
Recurring Fair Value Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member] | Other [Member]
Other assets [Abstract]
Derivatives assets at fair value	0	0
Other liabilities [Abstract]
Derivative liabilities at fair value	0	0
Recurring Fair Value Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member] | Mortgage commitment derivatives
Other assets [Abstract]
Derivatives assets at fair value	287	131
Other liabilities [Abstract]
Derivative liabilities at fair value	544	227
Recurring Fair Value Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member] | Fannie Mae [Member]
Liabilities [Abstract]
Long-term debt, fair value	7,204	7,810
Recurring Fair Value Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member] | Fannie Mae [Member] | Senior floating [Member]
Liabilities [Abstract]
Long-term debt, fair value	7,204	7,810
Recurring Fair Value Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member] | Consolidated Trusts [Member]
Liabilities [Abstract]
Long-term debt, fair value	26,356	29,911
Recurring Fair Value Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member] | Fannie Mae [Member]
Assets [Abstract]
Trading securities	1,617	2,905
Available-for-sale securities	1,700	1,911
Recurring Fair Value Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member] | Other agency [Member]
Assets [Abstract]
Trading securities	3,494	1,083
Available-for-sale securities	298	357
Recurring Fair Value Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member] | Alt-A and subprime private-label securities [Member]
Assets [Abstract]
Trading securities	1,430	259
Available-for-sale securities	623	1,237
Recurring Fair Value Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member] | CMBS [Member]
Assets [Abstract]
Trading securities		9
Available-for-sale securities		15
Recurring Fair Value Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member] | Mortgage revenue bonds [Member]
Assets [Abstract]
Trading securities	0	0
Available-for-sale securities	0	0
Recurring Fair Value Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member] | Other [Member]
Assets [Abstract]
Available-for-sale securities	9	10
Recurring Fair Value Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member] | U.S. Treasury securities [Member]
Assets [Abstract]
Trading securities	0	0
Recurring Fair Value Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member] | Other securities [Member]
Assets [Abstract]
Trading securities	97
Recurring Fair Value Measurements [Member] | Significant Unobservable Inputs (Level 3) [Member]
Assets [Abstract]
Cash equivalents	0
Trading securities	80	1,201
Available-for-sale securities	1,093	1,313
Mortgage loans held for investment, at fair value	1,018	1,116
Other assets [Abstract]
Derivatives assets at fair value	129	169
Total assets at fair value	2,320	3,799
Liabilities [Abstract]
Long-term debt, fair value	673	958
Other liabilities [Abstract]
Derivative liabilities at fair value	12	35
Total liabilities at fair value	685	993
Recurring Fair Value Measurements [Member] | Significant Unobservable Inputs (Level 3) [Member] | Swaps [Member]
Other assets [Abstract]
Derivatives assets at fair value	108	146
Other liabilities [Abstract]
Derivative liabilities at fair value	1	33
Recurring Fair Value Measurements [Member] | Significant Unobservable Inputs (Level 3) [Member] | Swaptions [Member]
Other assets [Abstract]
Derivatives assets at fair value	0	0
Other liabilities [Abstract]
Derivative liabilities at fair value	0	0
Recurring Fair Value Measurements [Member] | Significant Unobservable Inputs (Level 3) [Member] | Other [Member]
Other assets [Abstract]
Derivatives assets at fair value	20	22
Other liabilities [Abstract]
Derivative liabilities at fair value	1	1
Recurring Fair Value Measurements [Member] | Significant Unobservable Inputs (Level 3) [Member] | Mortgage commitment derivatives
Other assets [Abstract]
Derivatives assets at fair value	1	1
Other liabilities [Abstract]
Derivative liabilities at fair value	10	1
Recurring Fair Value Measurements [Member] | Significant Unobservable Inputs (Level 3) [Member] | Fannie Mae [Member]
Liabilities [Abstract]
Long-term debt, fair value	354	376
Recurring Fair Value Measurements [Member] | Significant Unobservable Inputs (Level 3) [Member] | Fannie Mae [Member] | Senior floating [Member]
Liabilities [Abstract]
Long-term debt, fair value	354	376
Recurring Fair Value Measurements [Member] | Significant Unobservable Inputs (Level 3) [Member] | Consolidated Trusts [Member]
Liabilities [Abstract]
Long-term debt, fair value	319	582
Recurring Fair Value Measurements [Member] | Significant Unobservable Inputs (Level 3) [Member] | Fannie Mae [Member]
Assets [Abstract]
Trading securities	79	971
Available-for-sale securities	204	208
Recurring Fair Value Measurements [Member] | Significant Unobservable Inputs (Level 3) [Member] | Other agency [Member]
Assets [Abstract]
Trading securities	0	35
Available-for-sale securities	0	0
Recurring Fair Value Measurements [Member] | Significant Unobservable Inputs (Level 3) [Member] | Alt-A and subprime private-label securities [Member]
Assets [Abstract]
Trading securities	0	194
Available-for-sale securities	26	77
Recurring Fair Value Measurements [Member] | Significant Unobservable Inputs (Level 3) [Member] | CMBS [Member]
Assets [Abstract]
Trading securities		0
Available-for-sale securities		0
Recurring Fair Value Measurements [Member] | Significant Unobservable Inputs (Level 3) [Member] | Mortgage revenue bonds [Member]
Assets [Abstract]
Trading securities	1	1
Available-for-sale securities	506	671
Recurring Fair Value Measurements [Member] | Significant Unobservable Inputs (Level 3) [Member] | Other [Member]
Assets [Abstract]
Available-for-sale securities	357	357
Recurring Fair Value Measurements [Member] | Significant Unobservable Inputs (Level 3) [Member] | U.S. Treasury securities [Member]
Assets [Abstract]
Trading securities	0	$ 0
Recurring Fair Value Measurements [Member] | Significant Unobservable Inputs (Level 3) [Member] | Other securities [Member]
Assets [Abstract]
Trading securities	$ 0

Fair Value Level 3 Rollforward

Fair Value Level 3 Rollforward (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Trading securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)	$ 3	$ 2	$ 3	$ 13
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	84	1,148	1,201	1,127
Total gains (losses) (realized/unrealized) Included in Net Income	(5)	7	80	18
Total gains (losses) (realized/unrealized) Included in Other Comprehensive Income (Loss)	0	0	0	0
Purchases	0	63	1	63
Sales	0	(21)	(1,060)	(21)
Issues	0	0	0	0
Settlements	0	(14)	(6)	(25)
Transfers out of Level 3	0	(21)	(137)	(22)
Transfers into Level 3	1	974	1	996
Ending Balance	80	2,136	80	2,136
Trading securities [Member] | Fannie Mae [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)	3	0	3	2
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	83	856	971	835
Total gains (losses) (realized/unrealized) Included in Net Income	(5)	1	166	4
Total gains (losses) (realized/unrealized) Included in Other Comprehensive Income (Loss)	0	0	0	0
Purchases	0	63	1	63
Sales	0	0	(1,060)	0
Issues	0	0	0	0
Settlements	0	(2)	0	(5)
Transfers out of Level 3	0	(21)	0	(22)
Transfers into Level 3	1	974	1	996
Ending Balance	79	1,871	79	1,871
Trading securities [Member] | Other agency [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)			0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance			35
Total gains (losses) (realized/unrealized) Included in Net Income			(1)
Total gains (losses) (realized/unrealized) Included in Other Comprehensive Income (Loss)			0
Purchases			0
Sales			0
Issues			0
Settlements			(1)
Transfers out of Level 3			(33)
Transfers into Level 3			0
Ending Balance	0		0
Trading securities [Member] | Alt-A and subprime private-label securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		2	0	11
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance		272	194	271
Total gains (losses) (realized/unrealized) Included in Net Income		3	(85)	11
Total gains (losses) (realized/unrealized) Included in Other Comprehensive Income (Loss)		0	0	0
Purchases		0	0	0
Sales		0	0	0
Issues		0	0	0
Settlements		(11)	(5)	(18)
Transfers out of Level 3		0	(104)	0
Transfers into Level 3		0	0	0
Ending Balance	0	264	0	264
Trading securities [Member] | Mortgage revenue bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)	0	0	0	0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	1	20	1	21
Total gains (losses) (realized/unrealized) Included in Net Income	0	3	0	3
Total gains (losses) (realized/unrealized) Included in Other Comprehensive Income (Loss)	0	0	0	0
Purchases	0	0	0	0
Sales	0	(21)	0	(21)
Issues	0	0	0	0
Settlements	0	(1)	0	(2)
Transfers out of Level 3	0	0	0	0
Transfers into Level 3	0	0	0	0
Ending Balance	1	1	1	1
Available-for-sale securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)	0	0	0	0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	1,119	2,039	1,313	2,153
Total gains (losses) (realized/unrealized) Included in Net Income	(3)	34	15	36
Total gains (losses) (realized/unrealized) Included in Other Comprehensive Income (Loss)	24	(54)	(40)	(43)
Purchases	0	0	0	0
Sales	(7)	(312)	(18)	(325)
Issues	0	0	0	0
Settlements	(40)	(49)	(173)	(163)
Transfers out of Level 3	0	(21)	(4)	(51)
Transfers into Level 3	0	0	0	30
Ending Balance	1,093	1,637	1,093	1,637
Available-for-sale securities [Member] | Fannie Mae [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)	0	0	0	0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	202	232	208	230
Total gains (losses) (realized/unrealized) Included in Net Income	1	0	1	1
Total gains (losses) (realized/unrealized) Included in Other Comprehensive Income (Loss)	4	(3)	0	(2)
Purchases	0	0	0	0
Sales	0	0	0	0
Issues	0	0	0	0
Settlements	(3)	(2)	(5)	(6)
Transfers out of Level 3	0	(21)	0	(47)
Transfers into Level 3	0	0	0	30
Ending Balance	204	206	204	206
Available-for-sale securities [Member] | Other agency [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)				0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance				5
Total gains (losses) (realized/unrealized) Included in Net Income				0
Total gains (losses) (realized/unrealized) Included in Other Comprehensive Income (Loss)				0
Purchases				0
Sales				(1)
Issues				0
Settlements				0
Transfers out of Level 3				(4)
Transfers into Level 3				0
Ending Balance		0		0
Available-for-sale securities [Member] | Alt-A and subprime private-label securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)	0	0	0	0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	27	205	77	217
Total gains (losses) (realized/unrealized) Included in Net Income	0	0	0	0
Total gains (losses) (realized/unrealized) Included in Other Comprehensive Income (Loss)	0	(21)	(45)	(15)
Purchases	0	0	0	0
Sales	0	0	0	0
Issues	0	0	0	0
Settlements	(1)	(6)	(2)	(24)
Transfers out of Level 3	0	0	(4)	0
Transfers into Level 3	0	0	0	0
Ending Balance	26	178	26	178
Available-for-sale securities [Member] | Mortgage revenue bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)	0	0	0	0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	539	1,185	671	1,272
Total gains (losses) (realized/unrealized) Included in Net Income	(11)	34	0	35
Total gains (losses) (realized/unrealized) Included in Other Comprehensive Income (Loss)	10	(11)	(3)	(12)
Purchases	0	0	0	0
Sales	(7)	(312)	(18)	(324)
Issues	0	0	0	0
Settlements	(25)	(23)	(144)	(98)
Transfers out of Level 3	0	0	0	0
Transfers into Level 3	0	0	0	0
Ending Balance	506	873	506	873
Available-for-sale securities [Member] | Other [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)	0	0	0	0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	351	417	357	429
Total gains (losses) (realized/unrealized) Included in Net Income	7	0	14	0
Total gains (losses) (realized/unrealized) Included in Other Comprehensive Income (Loss)	10	(19)	8	(14)
Purchases	0	0	0	0
Sales	0	0	0	0
Issues	0	0	0	0
Settlements	(11)	(18)	(22)	(35)
Transfers out of Level 3	0	0	0	0
Transfers into Level 3	0	0	0	0
Ending Balance	357	380	357	380
Mortgage loans [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)	8	19	16	16
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	1,102	1,149	1,116	1,197
Total gains (losses) (realized/unrealized) Included in Net Income	11	24	28	32
Total gains (losses) (realized/unrealized) Included in Other Comprehensive Income (Loss)	0	0	0	0
Purchases	0	0	0	0
Sales	0	0	0	0
Issues	0	0	0	0
Settlements	(79)	(55)	(127)	(117)
Transfers out of Level 3	(51)	(21)	(87)	(67)
Transfers into Level 3	35	22	88	74
Ending Balance	1,018	1,119	1,018	1,119
Net derivatives [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)	(14)	9	(37)	0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	133	113	134	44
Total gains (losses) (realized/unrealized) Included in Net Income	(28)	27	(86)	100
Total gains (losses) (realized/unrealized) Included in Other Comprehensive Income (Loss)	0	0	0	0
Purchases	0	0	0	0
Sales	0	0	0	0
Issues	0	0	0	0
Settlements	12	(16)	16	(24)
Transfers out of Level 3	0	0	53	5
Transfers into Level 3	0	0	0	(1)
Ending Balance	117	124	117	124
Long-term debt [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Liabilities Measured on Recurring Basis, Change in Unrealized Gain (Loss)	2	(19)	21	(22)
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	(819)	(564)	(958)	(588)
Total gains (losses) (realized/unrealized) Included in Net Income	7	(20)	29	(22)
Total gains (losses) (realized/unrealized) Included in Other Comprehensive Income (Loss)	0	0	0	0
Purchases	0	0	0	0
Sales	0	0	0	0
Issues	0	0	1	(2)
Settlements	21	12	31	19
Transfers out of Level 3	177	22	331	88
Transfers into Level 3	(59)	(575)	(107)	(620)
Ending Balance	(673)	(1,125)	(673)	(1,125)
Long-term debt [Member] | Consolidated Trusts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Liabilities Measured on Recurring Basis, Change in Unrealized Gain (Loss)	(1)	(5)	(1)	(4)
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	(462)	(214)	(582)	(241)
Total gains (losses) (realized/unrealized) Included in Net Income	4	(5)	7	(4)
Total gains (losses) (realized/unrealized) Included in Other Comprehensive Income (Loss)	0	0	0	0
Purchases	0	0	0	0
Sales	0	0	0	0
Issues	0	0	1	(2)
Settlements	21	12	31	19
Transfers out of Level 3	177	22	331	88
Transfers into Level 3	(59)	(575)	(107)	(620)
Ending Balance	(319)	(760)	(319)	(760)
Long-term debt [Member] | Senior floating [Member] | Fannie Mae [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Liabilities Measured on Recurring Basis, Change in Unrealized Gain (Loss)	3	(14)	22	(18)
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	(357)	(350)	(376)	(347)
Total gains (losses) (realized/unrealized) Included in Net Income	3	(15)	22	(18)
Total gains (losses) (realized/unrealized) Included in Other Comprehensive Income (Loss)	0	0	0	0
Purchases	0	0	0	0
Sales	0	0	0	0
Issues	0	0	0	0
Settlements	0	0	0	0
Transfers out of Level 3	0	0	0	0
Transfers into Level 3	0	0	0	0
Ending Balance	$ (354)	$ (365)	$ (354)	$ (365)

Fair Value Level 3 Valuation In

Fair Value Level 3 Valuation Inputs (Details) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Fair Value Inputs, Quantitative Information [Line Items]
Derivatives	$ 352	$ 150
Recurring Fair Value Measurements [Member]
Fair Value Inputs, Quantitative Information [Line Items]
Trading securities	42,381	34,679
Available-for-sale securities	3,723	4,843
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair Value Inputs, Quantitative Information [Line Items]
Trading securities	35,663	29,222
Available-for-sale securities	0	0
Assets, Fair Value Disclosure, Nonrecurring	0
Mortgage loans held-for-sale, at lower of cost or fair value	0	0
Liabilities, Fair Value Disclosure, Nonrecurring	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Recurring Fair Value Measurements [Member]
Fair Value Inputs, Quantitative Information [Line Items]
Trading securities	35,663	29,222
Available-for-sale securities	0	0
Significant Other Observable Inputs (Level 2) [Member]
Fair Value Inputs, Quantitative Information [Line Items]
Trading securities	6,638	4,256
Available-for-sale securities	2,630	3,530
Mortgage loans held-for-sale, at lower of cost or fair value	1,436	101
Liabilities, Fair Value Disclosure, Nonrecurring	0	0
Significant Other Observable Inputs (Level 2) [Member] | Recurring Fair Value Measurements [Member]
Fair Value Inputs, Quantitative Information [Line Items]
Trading securities	6,638	4,256
Available-for-sale securities	2,630	3,530
Significant Other Observable Inputs (Level 2) [Member] | Fair Value, Measurements, Nonrecurring [Member]
Fair Value Inputs, Quantitative Information [Line Items]
Mortgage loans held-for-sale, at lower of cost or fair value	298	14
Significant Unobservable Inputs (Level 3) [Member]
Fair Value Inputs, Quantitative Information [Line Items]
Trading securities	80	1,201
Available-for-sale securities	1,093	1,313
Mortgage loans held-for-sale, at lower of cost or fair value	13,894	5,333
Significant Unobservable Inputs (Level 3) [Member] | Recurring Fair Value Measurements [Member]
Fair Value Inputs, Quantitative Information [Line Items]
Trading securities	80	1,201
Available-for-sale securities	1,093	1,313
Derivatives	117	134
Significant Unobservable Inputs (Level 3) [Member] | Recurring Fair Value Measurements [Member] | Various Valuation Technique without Inputs [Member]
Fair Value Inputs, Quantitative Information [Line Items]
Derivatives	10	21
Significant Unobservable Inputs (Level 3) [Member] | Recurring Fair Value Measurements [Member] | Dealer Mark [Member]
Fair Value Inputs, Quantitative Information [Line Items]
Derivatives	107	113
Significant Unobservable Inputs (Level 3) [Member] | Fair Value, Measurements, Nonrecurring [Member]
Fair Value Inputs, Quantitative Information [Line Items]
Mortgage loans held-for-sale, at lower of cost or fair value	5,046	2,993
Significant Unobservable Inputs (Level 3) [Member] | Fair Value, Measurements, Nonrecurring [Member] | Single Vendor Without Inputs [Member]
Fair Value Inputs, Quantitative Information [Line Items]
Mortgage loans held-for-sale, at lower of cost or fair value	618	1,880
Significant Unobservable Inputs (Level 3) [Member] | Fair Value, Measurements, Nonrecurring [Member] | Various Valuation Technique without Inputs [Member]
Fair Value Inputs, Quantitative Information [Line Items]
Mortgage loans held-for-sale, at lower of cost or fair value	1	0
Significant Unobservable Inputs (Level 3) [Member] | Fair Value, Measurements, Nonrecurring [Member] | Consensus Without Inputs [Member]
Fair Value Inputs, Quantitative Information [Line Items]
Mortgage loans held-for-sale, at lower of cost or fair value	4,427	1,113
Agency | Significant Unobservable Inputs (Level 3) [Member] | Recurring Fair Value Measurements [Member]
Fair Value Inputs, Quantitative Information [Line Items]
Trading securities		1,006
Available-for-sale securities		208
Agency | Significant Unobservable Inputs (Level 3) [Member] | Recurring Fair Value Measurements [Member] | Single Vendor With Inputs [Member]
Fair Value Inputs, Quantitative Information [Line Items]
Trading securities		971
Available-for-sale securities		$ 112
Agency | Significant Unobservable Inputs (Level 3) [Member] | Recurring Fair Value Measurements [Member] | Single Vendor With Inputs [Member] | Trading securities [Member] | Minimum [Member]
Fair Value Inputs, Quantitative Information [Line Items]
Prepayment Speed (%)		0.00%
Spreads (%)		0.515%
Agency | Significant Unobservable Inputs (Level 3) [Member] | Recurring Fair Value Measurements [Member] | Single Vendor With Inputs [Member] | Trading securities [Member] | Maximum [Member]
Fair Value Inputs, Quantitative Information [Line Items]
Prepayment Speed (%)		177.00%
Spreads (%)		3.75%
Agency | Significant Unobservable Inputs (Level 3) [Member] | Recurring Fair Value Measurements [Member] | Single Vendor With Inputs [Member] | Trading securities [Member] | Weighted Average [Member]
Fair Value Inputs, Quantitative Information [Line Items]
Prepayment Speed (%)		160.00%
Spreads (%)		2.001%
Agency | Significant Unobservable Inputs (Level 3) [Member] | Recurring Fair Value Measurements [Member] | Single Vendor With Inputs [Member] | Available-for-sale securities [Member] | Minimum [Member]
Fair Value Inputs, Quantitative Information [Line Items]
Prepayment Speed (%)		0.00%
Spreads (%)		1.50%
Agency | Significant Unobservable Inputs (Level 3) [Member] | Recurring Fair Value Measurements [Member] | Single Vendor With Inputs [Member] | Available-for-sale securities [Member] | Maximum [Member]
Fair Value Inputs, Quantitative Information [Line Items]
Prepayment Speed (%)		175.70%
Spreads (%)		2.10%
Agency | Significant Unobservable Inputs (Level 3) [Member] | Recurring Fair Value Measurements [Member] | Single Vendor With Inputs [Member] | Available-for-sale securities [Member] | Weighted Average [Member]
Fair Value Inputs, Quantitative Information [Line Items]
Prepayment Speed (%)		147.10%
Spreads (%)		1.823%
Agency | Significant Unobservable Inputs (Level 3) [Member] | Recurring Fair Value Measurements [Member] | Various Valuation Technique without Inputs [Member]
Fair Value Inputs, Quantitative Information [Line Items]
Trading securities	79	$ 35
Available-for-sale securities	204	96
Alt-A and subprime private-label securities [Member] | Recurring Fair Value Measurements [Member]
Fair Value Inputs, Quantitative Information [Line Items]
Trading securities	1,430	453
Available-for-sale securities	649	1,314
Alt-A and subprime private-label securities [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Recurring Fair Value Measurements [Member]
Fair Value Inputs, Quantitative Information [Line Items]
Trading securities	0	0
Available-for-sale securities	0	0
Alt-A and subprime private-label securities [Member] | Significant Other Observable Inputs (Level 2) [Member] | Recurring Fair Value Measurements [Member]
Fair Value Inputs, Quantitative Information [Line Items]
Trading securities	1,430	259
Available-for-sale securities	623	1,237
Alt-A and subprime private-label securities [Member] | Significant Unobservable Inputs (Level 3) [Member] | Recurring Fair Value Measurements [Member]
Fair Value Inputs, Quantitative Information [Line Items]
Trading securities	0	194
Available-for-sale securities	26	77
Alt-A and subprime private-label securities [Member] | Significant Unobservable Inputs (Level 3) [Member] | Recurring Fair Value Measurements [Member] | Various Valuation Technique without Inputs [Member]
Fair Value Inputs, Quantitative Information [Line Items]
Trading securities		40
Available-for-sale securities	26	77
Alt-A and subprime private-label securities [Member] | Significant Unobservable Inputs (Level 3) [Member] | Recurring Fair Value Measurements [Member] | Consensus Without Inputs [Member]
Fair Value Inputs, Quantitative Information [Line Items]
Trading securities		154
Mortgage revenue bonds [Member] | Recurring Fair Value Measurements [Member]
Fair Value Inputs, Quantitative Information [Line Items]
Trading securities	1	1
Available-for-sale securities	506	671
Mortgage revenue bonds [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Recurring Fair Value Measurements [Member]
Fair Value Inputs, Quantitative Information [Line Items]
Trading securities	0	0
Available-for-sale securities	0	0
Mortgage revenue bonds [Member] | Significant Other Observable Inputs (Level 2) [Member] | Recurring Fair Value Measurements [Member]
Fair Value Inputs, Quantitative Information [Line Items]
Trading securities	0	0
Available-for-sale securities	0	0
Mortgage revenue bonds [Member] | Significant Unobservable Inputs (Level 3) [Member] | Recurring Fair Value Measurements [Member]
Fair Value Inputs, Quantitative Information [Line Items]
Trading securities	1	1
Available-for-sale securities	506	671
Mortgage revenue bonds [Member] | Significant Unobservable Inputs (Level 3) [Member] | Recurring Fair Value Measurements [Member] | Single Vendor With Inputs [Member]
Fair Value Inputs, Quantitative Information [Line Items]
Available-for-sale securities	$ 389	$ 475
Mortgage revenue bonds [Member] | Significant Unobservable Inputs (Level 3) [Member] | Recurring Fair Value Measurements [Member] | Single Vendor With Inputs [Member] | Available-for-sale securities [Member] | Minimum [Member]
Fair Value Inputs, Quantitative Information [Line Items]
Spreads (%)	0.015%	(0.17%)
Mortgage revenue bonds [Member] | Significant Unobservable Inputs (Level 3) [Member] | Recurring Fair Value Measurements [Member] | Single Vendor With Inputs [Member] | Available-for-sale securities [Member] | Maximum [Member]
Fair Value Inputs, Quantitative Information [Line Items]
Spreads (%)	3.204%	2.48%
Mortgage revenue bonds [Member] | Significant Unobservable Inputs (Level 3) [Member] | Recurring Fair Value Measurements [Member] | Single Vendor With Inputs [Member] | Available-for-sale securities [Member] | Weighted Average [Member]
Fair Value Inputs, Quantitative Information [Line Items]
Spreads (%)	0.51%	0.39%
Mortgage revenue bonds [Member] | Significant Unobservable Inputs (Level 3) [Member] | Recurring Fair Value Measurements [Member] | Various Valuation Technique without Inputs [Member]
Fair Value Inputs, Quantitative Information [Line Items]
Trading securities	$ 1	$ 1
Available-for-sale securities	117	196
Other [Member] | Recurring Fair Value Measurements [Member]
Fair Value Inputs, Quantitative Information [Line Items]
Available-for-sale securities	366	367
Other [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Recurring Fair Value Measurements [Member]
Fair Value Inputs, Quantitative Information [Line Items]
Available-for-sale securities	0	0
Other [Member] | Significant Other Observable Inputs (Level 2) [Member] | Recurring Fair Value Measurements [Member]
Fair Value Inputs, Quantitative Information [Line Items]
Available-for-sale securities	9	10
Other [Member] | Significant Unobservable Inputs (Level 3) [Member] | Recurring Fair Value Measurements [Member]
Fair Value Inputs, Quantitative Information [Line Items]
Available-for-sale securities	357	357
Other [Member] | Significant Unobservable Inputs (Level 3) [Member] | Recurring Fair Value Measurements [Member] | Various Valuation Technique without Inputs [Member]
Fair Value Inputs, Quantitative Information [Line Items]
Available-for-sale securities	52	32
Other [Member] | Significant Unobservable Inputs (Level 3) [Member] | Recurring Fair Value Measurements [Member] | Discounted Cash Flow with Inputs [Member]
Fair Value Inputs, Quantitative Information [Line Items]
Available-for-sale securities	$ 305	$ 325
Other [Member] | Significant Unobservable Inputs (Level 3) [Member] | Recurring Fair Value Measurements [Member] | Discounted Cash Flow with Inputs [Member] | Available-for-sale securities [Member] | Minimum [Member]
Fair Value Inputs, Quantitative Information [Line Items]
Default Rate (%)	3.80%
Prepayment Speed (%)	6.50%	1.60%
Severity (%)	95.00%	50.00%
Spreads (%)	0.685%	0.848%
Other [Member] | Significant Unobservable Inputs (Level 3) [Member] | Recurring Fair Value Measurements [Member] | Discounted Cash Flow with Inputs [Member] | Available-for-sale securities [Member] | Maximum [Member]
Fair Value Inputs, Quantitative Information [Line Items]
Default Rate (%)	3.80%
Prepayment Speed (%)	6.50%	2.50%
Severity (%)	95.00%	88.00%
Spreads (%)	4.00%	6.07%
Other [Member] | Significant Unobservable Inputs (Level 3) [Member] | Recurring Fair Value Measurements [Member] | Discounted Cash Flow with Inputs [Member] | Available-for-sale securities [Member] | Weighted Average [Member]
Fair Value Inputs, Quantitative Information [Line Items]
Default Rate (%)	3.80%
Prepayment Speed (%)	6.50%	2.50%
Severity (%)	95.00%	86.60%
Spreads (%)	3.99%	5.779%

Fair Value Level 3 Valuation -

Fair Value Level 3 Valuation - Nonrecurring (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Fair Value Inputs, Quantitative Information [Line Items]
Mortgage loans held for investment, at fair value	$ 9,628	$ 10,596
Significant Other Observable Inputs (Level 2) [Member]
Fair Value Inputs, Quantitative Information [Line Items]
Mortgage loans held-for-sale, at lower of cost or fair value	1,436	101
Mortgage loans held for investment, at fair value	2,917,541	2,886,470
Total assets at fair value	2,962,345	2,948,237
Significant Unobservable Inputs (Level 3) [Member]
Fair Value Inputs, Quantitative Information [Line Items]
Mortgage loans held-for-sale, at lower of cost or fair value	13,894	5,333
Mortgage loans held for investment, at fair value	231,082	315,719
Total assets at fair value	246,650	324,173
Fair Value, Measurements, Nonrecurring [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value Inputs, Quantitative Information [Line Items]
Mortgage loans held-for-sale, at lower of cost or fair value	298	14
Fair Value, Measurements, Nonrecurring [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value Inputs, Quantitative Information [Line Items]
Mortgage loans held-for-sale, at lower of cost or fair value	5,046	2,993
Total assets at fair value	6,978	6,142
Fair Value, Measurements, Nonrecurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Single Vendor Without Inputs [Member]
Fair Value Inputs, Quantitative Information [Line Items]
Mortgage loans held-for-sale, at lower of cost or fair value	618	1,880
Fair Value, Measurements, Nonrecurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Consensus Without Inputs [Member]
Fair Value Inputs, Quantitative Information [Line Items]
Mortgage loans held-for-sale, at lower of cost or fair value	4,427	1,113
Fair Value, Measurements, Nonrecurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Various Valuation Technique without Inputs [Member]
Fair Value Inputs, Quantitative Information [Line Items]
Mortgage loans held-for-sale, at lower of cost or fair value	1	0
Other assets	$ 1	$ 2
Fair Value, Measurements, Nonrecurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Accepted Offers [Member]
Fair Value Inputs, Quantitative Information [Line Items]
Number of Acquired Properties Valuated, Percentage	19.00%	18.00%
Fair Value, Measurements, Nonrecurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Proprietary Home Price Model and Appraisals [Member]
Fair Value Inputs, Quantitative Information [Line Items]
Number of Acquired Properties Valuated, Percentage	76.00%	77.00%
Fair Value, Measurements, Nonrecurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Single-family [Member]
Fair Value Inputs, Quantitative Information [Line Items]
Acquired property, net	$ 970	$ 1,310
Fair Value, Measurements, Nonrecurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Single-family [Member] | Various Valuation Technique without Inputs [Member]
Fair Value Inputs, Quantitative Information [Line Items]
Acquired property, net	38	113
Fair Value, Measurements, Nonrecurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Single-family [Member] | Internal Model [Member]
Fair Value Inputs, Quantitative Information [Line Items]
Mortgage loans held for investment, at fair value	790	1,623
Acquired property, net	211	319
Fair Value, Measurements, Nonrecurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Single-family [Member] | Accepted Offers [Member]
Fair Value Inputs, Quantitative Information [Line Items]
Acquired property, net	181	218
Fair Value, Measurements, Nonrecurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Single-family [Member] | Appraisals [Member]
Fair Value Inputs, Quantitative Information [Line Items]
Acquired property, net	386	438
Fair Value, Measurements, Nonrecurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Single-family [Member] | Walk Forwards [Member]
Fair Value Inputs, Quantitative Information [Line Items]
Acquired property, net	154	222
Fair Value, Measurements, Nonrecurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Multifamily [Member]
Fair Value Inputs, Quantitative Information [Line Items]
Mortgage loans held for investment, at fair value	155	195
Fair Value, Measurements, Nonrecurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Multifamily [Member] | Various Valuation Technique without Inputs [Member]
Fair Value Inputs, Quantitative Information [Line Items]
Mortgage loans held for investment, at fair value	24	32
Acquired property, net	16	19
Fair Value, Measurements, Nonrecurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Multifamily [Member] | Asset Manager Estimate [Member]
Fair Value Inputs, Quantitative Information [Line Items]
Mortgage loans held for investment, at fair value	$ 131	$ 163

Fair Value Fair Value of Financ

Fair Value Fair Value of Financial Instruments (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Fair Value Measurement [Domain]
Financial assets [Abstract]
Derivative assets, gross amount offset	$ (2,608)	$ (4,272)
Financial liabilities [Abstract]
Derivative liabilities, gross amount offset	(2,756)	(4,979)
Mortgage loans held for investment, at fair value	9,628	10,596
Derivative assets, gross amount offset	(2,608)	(4,272)
Derivative liabilities, gross amount offset	(2,756)	(4,979)
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Financial assets [Abstract]
Cash and cash equivalents and restricted cash	37,679	35,060
Federal funds sold and securities purchased under agreements to resell or similar arrangements	0	0
Trading securities	35,663	29,222
Available-for-sale securities	0	0
Mortgage loans held for sale	0	0
Mortgage loans held for investment, at fair value	0	0
Advances to lenders	0	0
Derivatives assets at fair value	0	0
Guaranty assets and buy-ups	0	0
Total financial assets	73,342	64,282
Financial liabilities [Abstract]
Derivative liabilities at fair value	0	0
Guaranty obligations	0	0
Total financial liabilities	0	0
Significant Other Observable Inputs (Level 2) [Member]
Financial assets [Abstract]
Cash and cash equivalents and restricted cash	11,050	25,200
Federal funds sold and securities purchased under agreements to resell or similar arrangements	16,300	19,470
Trading securities	6,638	4,256
Available-for-sale securities	2,630	3,530
Mortgage loans held for sale	1,436	101
Mortgage loans held for investment, at fair value	2,917,541	2,886,470
Advances to lenders	3,899	4,936
Derivatives assets at fair value	2,851	4,274
Guaranty assets and buy-ups	0	0
Total financial assets	2,962,345	2,948,237
Financial liabilities [Abstract]
Derivative liabilities at fair value	3,348	5,272
Guaranty obligations	0	0
Total financial liabilities	3,231,716	3,302,681
Significant Unobservable Inputs (Level 3) [Member]
Financial assets [Abstract]
Cash and cash equivalents and restricted cash	0	0
Federal funds sold and securities purchased under agreements to resell or similar arrangements	0	0
Trading securities	80	1,201
Available-for-sale securities	1,093	1,313
Mortgage loans held for sale	13,894	5,333
Mortgage loans held for investment, at fair value	231,082	315,719
Advances to lenders	2	2
Derivatives assets at fair value	129	169
Guaranty assets and buy-ups	370	436
Total financial assets	246,650	324,173
Financial liabilities [Abstract]
Derivative liabilities at fair value	12	35
Guaranty obligations	121	456
Total financial liabilities	42,250	42,389
Fannie Mae [Member]
Financial liabilities [Abstract]
Long-term debt	7,558	8,186
Fannie Mae [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Financial liabilities [Abstract]
Short-term debt	0	0
Long-term debt	0	0
Fannie Mae [Member] | Significant Other Observable Inputs (Level 2) [Member]
Financial liabilities [Abstract]
Short-term debt	25,730	33,379
Long-term debt	228,853	249,780
Fannie Mae [Member] | Significant Unobservable Inputs (Level 3) [Member]
Financial liabilities [Abstract]
Short-term debt	0	0
Long-term debt	791	837
Consolidated Trusts [Member]
Financial liabilities [Abstract]
Long-term debt	26,675	30,493
Consolidated Trusts [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Financial liabilities [Abstract]
Short-term debt	0	0
Long-term debt	0	0
Consolidated Trusts [Member] | Significant Other Observable Inputs (Level 2) [Member]
Financial liabilities [Abstract]
Short-term debt	0	0
Long-term debt	2,973,785	3,014,250
Consolidated Trusts [Member] | Significant Unobservable Inputs (Level 3) [Member]
Financial liabilities [Abstract]
Short-term debt	338	378
Long-term debt	40,988	40,683
Carrying Value [Member]
Financial assets [Abstract]
Cash and cash equivalents and restricted cash	48,729	60,260
Federal funds sold and securities purchased under agreements to resell or similar arrangements	16,300	19,470
Trading securities	42,381	34,679
Available-for-sale securities	3,723	4,843
Mortgage loans held for sale	14,323	4,988
Mortgage loans held for investment, at fair value	3,194,301	3,173,537
Advances to lenders	3,901	4,938
Derivatives assets at fair value	372	171
Guaranty assets and buy-ups	151	149
Total financial assets	3,324,181	3,303,035
Financial liabilities [Abstract]
Derivative liabilities at fair value	604	328
Guaranty obligations	163	258
Total financial liabilities	3,338,256	3,330,640
Carrying Value [Member] | Fannie Mae [Member]
Financial liabilities [Abstract]
Short-term debt	25,726	33,377
Long-term debt	224,964	243,375
Carrying Value [Member] | Consolidated Trusts [Member]
Financial liabilities [Abstract]
Short-term debt	339	379
Long-term debt	3,086,460	3,052,923
Estimated of Fair Value [Member]
Financial assets [Abstract]
Cash and cash equivalents and restricted cash	48,729	60,260
Federal funds sold and securities purchased under agreements to resell or similar arrangements	16,300	19,470
Trading securities	42,381	34,679
Available-for-sale securities	3,723	4,843
Mortgage loans held for sale	15,330	5,434
Mortgage loans held for investment, at fair value	3,148,623	3,202,189
Advances to lenders	3,901	4,938
Derivatives assets at fair value	372	171
Guaranty assets and buy-ups	370	436
Total financial assets	3,279,729	3,332,420
Financial liabilities [Abstract]
Derivative liabilities at fair value	604	328
Guaranty obligations	121	456
Total financial liabilities	3,271,210	3,340,091
Estimated of Fair Value [Member] | Fannie Mae [Member]
Financial liabilities [Abstract]
Short-term debt	25,730	33,379
Long-term debt	229,644	250,617
Estimated of Fair Value [Member] | Consolidated Trusts [Member]
Financial liabilities [Abstract]
Short-term debt	338	378
Long-term debt	$ 3,014,773	$ 3,054,933

Fair Value Fair Value Option (D

Fair Value Fair Value Option (Details) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Fair Value, Option, Quantitative Disclosures [Line Items]
Mortgage loans held for investment, at fair value	$ 9,628	$ 10,596
Fair value of nonaccrual loans	181	227
Difference between unpaid principal balance and the fair value of nonaccrual loans	28	46
Fair value of loans that are 90 days or more past due	131	159
Difference between unpaid principal balance and the fair value of these 90 days or more past due loans	$ 22	$ 34
Single-family [Member] | Minimum [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Serious delinquency, days past due	90 days	90 days
Fannie Mae [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Long-term debt, fair value	$ 7,558	$ 8,186
Consolidated Trusts [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Long-term debt, fair value	26,675	30,493
Loans [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Loans, unpaid principal balance	9,510	10,246
Long-term debt [Member] | Fannie Mae [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Long-term debt, fair value	7,558	8,186
Long-term debt, unpaid principal balance	6,780	7,368
Long-term debt [Member] | Consolidated Trusts [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Long-term debt, fair value	26,675	30,493
Long-term debt, unpaid principal balance	$ 24,695	$ 27,717

Fair Value Changes in FV under

Fair Value Changes in FV under the FV Option (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Loans [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair value (gains) losses, net	$ 27	$ (94)	$ 176	$ (136)
Long-term debt [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Changes in instrument-specific credit risk - Long-Term Debt	$ (247)	$ 288	$ (501)	$ 457