Financing Receivable, before Allowance for Credit Loss, by Origination Year [Abstract] Financing Receivable, before Allowance for Credit Loss, by Origination Year [Abstract] Revision of Prior Period [Axis] Revision of Prior Period [Axis] Single-Family Single Family Segment [Member] Single Family Segment Schedule of Investments in Trading Securities [Line Items] Debt and Equity Securities, FV-NI [Line Items] Short-Term Debt Schedule of Short-Term Debt [Table Text Block] Cash collateral posted for derivative instruments Derivative Asset, Subject to Master Netting Arrangement, Collateral, Obligation to Return Cash, Offset Against Derivative Asset Award Timing Predetermined Award Timing Predetermined [Flag] Less than or equal to 80% Original Loan to Value Ratio Less than or Equal to Eighty Percent [Member] Represents loans with an original loan-to-value ratio less than or equal to 80%. Entity File Number Entity File Number Reclassification adjustment for gains (losses) included in net income, net of taxes Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, Net of Tax Tabular List, Table Tabular List [Table Text Block] Interest Rate Risk On Debt Interest Rate Risk On Debt [Member] Interest rate risk on debt New Accounting Guidance New Accounting Pronouncements, Policy [Policy Text Block] Schedule of Related Party Transactions Schedule of Related Party Transactions [Table Text Block] Secured Overnight Financing Rate (SOFR) Secured Overnight Financing Rate (SOFR) [Member] Fair Value of Financial Instruments Fair Value, by Balance Sheet Grouping [Table Text Block] Forward contracts to sell mortgage-related securities Forward Contracts to Sell Mortgage-related Securities [Member] Represents forward contract/commitment to sell mortgage-related securities. Fair Value Measurements Using Significant Unobservable Inputs (Level3) [Table] Fair Value Assets and Liabilities Measured on Recurring Basis Unobservable Input Reconciliation Table [Table] Summarization of information required and determined to be provided for purposes of reconciling beginning and ending balances of fair value measurements of assets and liabilities using significant unobservable inputs (Level 3). Such reconciliation, separately presenting changes during the period, at a minimum, may include: (1) total gains or losses for the period (realized and unrealized), segregating those gains or losses included in earnings (or changes in net assets or liabilities), and a description of where those gains or losses included in earnings (or changes in net assets or liabilities) are reported in the statement of income (or activities); (2) purchases, sales, issuances, and settlements (net); and (3) transfers in and transfers out of Level 3 (for example, transfers due to changes in the observability of significant inputs). Maximum Exposure Guarantor Obligations, Maximum Exposure, Undiscounted Available-for-Sale Securities Debt Securities [Member] Research and development Effective Income Tax Rate Reconciliation, Tax Credit, Research, Amount Guaranty obligations Guarantees, Fair Value Disclosure Loans held for investment, excluding fair value option Financing Receivable, Excluding Fair Value Option, before Allowance for Credit Loss Financing Receivable, Excluding Fair Value Option, before Allowance for Credit Loss Measurement Basis [Axis] Measurement Basis [Axis] Adjustment to Compensation: Adjustment to Compensation [Axis] Named Executive Officers, Footnote Named Executive Officers, Footnote [Text Block] Convertible Series 2004-1 Convertible Series 2004-1 Preferred Stock [Member] Outstanding Convertible Series 2004-1 Preferred Stock, convertible at any time, at the option of holders, into shares of Fannie Mae common stock. The conversion price is adjustable, as necessary, to maintain the stated conversion rate into common stock. Financing Receivable Portfolio Segment [Domain] Financing Receivable Portfolio Segment [Domain] Recoveries Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Recovery Stock, Class of Stock [Table] Stock, Class of Stock [Table] Fair value gains (losses), net Changes in fair value, gain (loss) Fair Value, Option, Changes in Fair Value, Gain (Loss) Cash collateral received for derivative instruments Derivative Liability, Subject to Master Netting Arrangement, Collateral, Right to Reclaim Cash Offset Minimum Capital Ratio Requirement Banking Regulation, Common Equity Tier 1 Risk-Based Capital Ratio, Capital Adequacy, Minimum Current income tax benefit (provision) Current Income Tax Expense (Benefit) TCCA, increase of guarantee fee rate Increase of Guarantee Fee Rate Resulting from the Temporary Payroll Tax Cut Continuation Act of 2011. Increase in guaranty fee on single-family residential mortgages required by the Temporary Payroll Tax Cut Continuation Act of 2011. Schedule of Delinquency Status Guaranty Book of Business Schedule Of Delinquency Status Guaranty Book of Business [Table Text Block] Tabular disclosure of current delinquency status of our single-family conventional and total multifamily guaranty book of business. Adjustment to Compensation, Amount Adjustment to Compensation Amount Concentration risk, percentage Concentration Risk, Percentage Borrowings that have an original maturity of three months or less, net Proceeds from (Repayments of) Short-Term Debt, Maturing in Three Months or Less Principles of Consolidation Consolidation, Policy [Policy Text Block] Internal Model and Walk Forward Internal Model and Walk Forward [Member] Internal Model and Walk Forward Employee Stock Option Share-Based Payment Arrangement, Option [Member] Cash and Restricted Cash Cash and Cash Equivalents, Policy [Policy Text Block] Series 2008-2 Senior Preferred Stock Series 2008-2 Senior Preferred Stock [Member] Series 2008-2 Senior Preferred Stock -issued on September 8, 2008 one million of variable liquidation preference senior preferred stock with an aggregate stated value of $1.0 billion agreement with Treasury. Senior preferred stock ranks senior to all other series of preferred stock as both dividends and distribution upon dissolution, liquidation or winding up the company. Effective Income Tax Rate Reconciliation, Percent Effective Income Tax Rate Reconciliation, Percent [Abstract] Derivatives, Offsetting Derivatives, Offsetting Fair Value Amounts, Policy [Policy Text Block] Total stockholders’ equity Equity, Attributable to Parent Measurement Frequency [Axis] Measurement Frequency [Axis] Other comprehensive income, net of tax effect: Other Comprehensive Income (Loss), Net of Tax [Abstract] Insider Trading Policies and Procedures [Line Items] New York NEW YORK Financial assets: Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract] Stock issued (in shares) Stock Issued During Period, Shares, New Issues Recurring Fair Value, Recurring [Member] Financing Receivable, Allowance for Credit Loss, Writeoff, by Origination Year [Abstract] Financing Receivable, Allowance for Credit Loss, Writeoff, by Origination Year [Abstract] Single family loans redesignated from HFI to HFS, lower of cost or fair value adjustment at time of redesignation Financing Receivable, Transfer to Held-for-Sale, Allowance for Credit Loss, Adjustment, Other Financing Receivable, Transfer to Held-for-Sale, Allowance for Credit Loss, Adjustment, Other Risk Characteristics of our Guaranty Book of Business Concentration Risk, Credit Risk, Policy [Policy Text Block] LIABILITIES AND EQUITY Liabilities and Equity [Abstract] Cover [Abstract] Cover [Abstract] Portion at Fair Value Measurement [Member] Portion at Fair Value Measurement [Member] Transfers from mortgage loans to other assets Real Estate Owned, Transfer to Real Estate Owned Maximum Maximum [Member] Fair Value Measurements Using Significant Unobservable Input (Level 3) Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block] Tabular disclosure of the fair value measurement of assets and liabilities using significant unobservable inputs (Level 3), a reconciliation of the beginning and ending balances, separately presenting changes during the period attributable to the following: (1) total gains or losses for the period (realized and unrealized), segregating those gains or losses included in earnings (or changes in net assets) and gains or losses recognized in other comprehensive income (loss), and a description of where those gains or losses included in earnings (or changes in net assets) are reported in the statement of income (or activities); (2) purchases, sales, issues, and settlements (each type disclosed separately); and (3) transfers in and transfers out of Level 3 (for example, transfers due to changes in the observability of significant inputs), by class of asset and liability. Non-PEO NEO Average Total Compensation Amount Non-PEO NEO Average Total Compensation Amount Total gains (losses) realized & unrealized Fair Value, Liability, Recurring Basis, Still Held, Unrealized Gain (Loss) Long-Term Debt [Line Items] Debt Instrument [Line Items] Concentrations of Credit Risk Concentration Risk Disclosure [Text Block] Financial Guarantees Off-Balance-Sheet Credit Exposure, Policy [Policy Text Block] Adjustment to Non-PEO NEO Compensation Footnote Adjustment to Non-PEO NEO Compensation Footnote [Text Block] Financing Receivable, Credit Quality Indicator [Table] Financing Receivable, Credit Quality Indicator [Table] Forgone Recovery due to Disqualification of Tax Benefits, Amount Forgone Recovery due to Disqualification of Tax Benefits, Amount Three fiscal years, writeoff Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year, Writeoff Non-Rule 10b5-1 Arrangement Terminated Non-Rule 10b5-1 Arrangement Terminated [Flag] Income before federal income taxes Income before U.S. federal income taxes Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Entity Shell Company Entity Shell Company Total Capital Requirement Ratio (including Buffers) Banking Regulation, Tier 1 Leverage Capital Ratio, Actual Schedule of Long-term Debt Instruments [Table] Schedule of Long-Term Debt Instruments [Table] Single family loans redesignated from HFS to HFI, amortized cost Financing Receivable Reclassification To Be Held For Investment Financing Receivable Reclassification To Be Held For Investment Proceeds from the issuance of debt Proceeds from Issuance of Debt Hedged liability, discontinued fair value, remaining adjustments Hedged Liability, Discontinued Fair Value Hedge, Cumulative Increase (Decrease) Statement of Stockholders' Equity [Abstract] Statement of Stockholders' Equity [Abstract] Operating Segments Operating Segments [Member] Schedule of Non-Cash Activities Schedule of Cash Flow, Supplemental Disclosures [Table Text Block] Award Timing MNPI Considered Award Timing MNPI Considered [Flag] Total interest expense Interest Expense, Operating Pay-fixed Pay-fixed Swap [Member] Represents an agreement under which we pay a predetermined fixed rate of interest based upon a set notional principal amount and receive a variable interest payment based upon a stated index, with the index resetting at regular intervals over a specified period of time. These contracts generally increase in value as interest rates rise and decrease in value interest rates fall. Primarily Discounted Cash Flow, Single Vendor, and Consensus Primarily Discounted Cash Flow, Single Vendor, and Consensus [Member] Primarily Discounted Cash Flow, Single Vendor, and Consensus Texas TEXAS Series P Series P Preferred Stock [Member] Outstanding Series P Preferred Stock classified within stockholders' equity has no par value, is non-participating, is non-voting and has a liquidation preference equal to the stated value per share. 15-year or less, amortizing fixed-rate 15-year or less, amortizing fixed-rate (less than) Fixed Rate Residential Mortgage 15 Year [Member] Loan to purchase or refinance residential real estate such as a home, in which the real estate itself serves as collateral for the loan and in which the interest rate and the amount of each payment remain constant throughout the life of the loan (15 year) Document Fiscal Period Focus Document Fiscal Period Focus Senior preferred stock authorized (in shares) Senior Preferred Stock, Share Authorized Senior Preferred Stock, Share Authorized Fair Value Option Fair Value Option, Disclosures [Table Text Block] Investments in securities and other Interest Income, Debt Securities, Operating Award Timing Method Award Timing Method [Text Block] Litigation Case [Domain] Litigation Case [Domain] Award Type Award Type [Axis] Fannie Mae Parent Company [Member] Callable Callable [Member] A debt security whose issuer has the right to redeem the security at a specified price on or after a specified date, prior to its stated final maturity. 30 days delinquent (percentage of conventional loans) Number of Loans 30 to 59 Days Past Due, Percentage Represents the percentage of loans that are 30 to 59 days past due. Calculated based on the number of loans in the delinquency bucket indicated, divided by the total number of loans in the respective category. Single-family loans sold, unpaid principal balance Financing Receivable, Sale and Reclassification to Held-for-Sale Valuation allowance Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Percent Long-term debt Interest Expense: Long-Term Debt Interest Expense, Long-Term Debt Credit enhancement derivatives Credit Enhancement [Member] Credit Enhancement Entity Address, City or Town Entity Address, City or Town Qualitative and Quantitative Information, Transferor's Continuing Involvement in Transferred Financial Assets, Transfer or Transferee [Domain] Qualitative and Quantitative Information, Transferor's Continuing Involvement in Transferred Financial Assets, Transfer or Transferee [Domain] Seriously delinquent (percentage of book of business) Loans Seriously Delinquent, Percentage of Unpaid Principal Balance Represents the percentage unpaid principal balance comprised of single-family loans greater than or equal to 90 days past due or multifamily loans greater than or equal to 60 days past due. Calculated based on the aggregate unpaid principal balance for the category indicated, divided by the respective book of business. Net trading gains (losses) recognized in the period related to securities still held at period end Debt Securities, Trading, Unrealized Gain (Loss) Medium-term notes Senior Fixed Medium-term Notes [Member] Senior fixed medium-term notes represent debt instruments with original contractual maturities ranging from one to ten years, excluding zero-coupon debt. Senior fixed rate debt takes priority over other debt instruments sold by the company. In the event the company goes bankrupt, senior fixed rate debt holders receive priority for repayment prior to junior or unsecured general creditors. Class of Financing Receivable [Axis] Class of Financing Receivable [Axis] Class of Financing Receivable [Axis] Non-PEO NEO Average Compensation Actually Paid Amount Non-PEO NEO Average Compensation Actually Paid Amount Statement of Income Location, Balance [Domain] Statement of Income Location, Balance [Domain] Single Class MBS, REMIC & Megas Single Class MBS, REMIC & Megas [Member] Fannie Mae Single-class Mortgage-Backed Securities (MBS) are MBS in which the investors receive principal and interest payments in proportion to their percentage ownership of the MBS issuance. Fannie Mae Megas are large pools of Fannie Mae MBS backed by smaller pools of Fannie Mae MBS or by other Fannie Mae-backed Megas. Real Estate Mortgage Investment Conduit (REMIC) refers to a type of mortgage-related security in which interest and principal payments from mortgages or mortgage-related securities are structured into separately traded securities. Stripped Mortgage-Backed Securities (SMBS) are created by "stripping" or separating the principal and interest payments from the underlying pool of mortgages into two classes of securities, with each receiving a different proportion of the principal and interest payments. Compensation Actually Paid vs. Other Measure Compensation Actually Paid vs. Other Measure [Text Block] Short-term debt Interest Expense, Short-Term Borrowings Entity Emerging Growth Company Entity Emerging Growth Company 2028 Long-Term Debt, Maturity, Year Three Consolidations and Transfers of Financial Assets [Abstract] Consolidations and Transfers of Financial Assets [Abstract] Total Capital Requirement Ratio (including Buffers) Banking Regulation, Common Equity Tier 1 Risk-Based Capital Ratio, Actual Other adjustments, amount Effective Income Tax Rate Reconciliation, Other Reconciling Items, Amount [Abstract] Change in Fair Value as of Vesting Date of Prior Year Equity Awards Vested in Covered Year Change in Fair Value as of Vesting Date of Prior Year Equity Awards Vested in Covered Year [Member] Debt instruments Deferred Tax Liabilities, Deferred Expense, Debt Issuance Costs Total risk management derivatives fair value gains (losses), net Derivative, Gain (Loss) on Derivative, Net Purchases Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Purchases Non-interest income Noninterest Income Common stock, shares outstanding (in shares) Common Stock, Shares, Outstanding Loans in Mortgage Portfolio [Line Items] Loans In Mortgage Portfolio [Line Items] Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. Net change in securities purchased under agreements to resell Proceeds from (Payments for) Federal Funds Sold and Securities Purchased under Agreements to Resell, Net Series Q Series Q Preferred Stock [Member] Outstanding Series Q Preferred Stock. This stock has no par value, is non-participating, is non-voting and has a liquidation preference equal to the stated value per share. Non-interest expense: Noninterest Expense [Abstract] Adjusted total capital Banking Regulation, Adjusted Total Capital [Abstract] Banking Regulation, Adjusted Total Capital Class of Financing Receivable [Domain] Class of Financing Receivable [Domain] Class of Financing Receivable [Domain] Mortgage loans Mortgage loans [Member] Mortgage loans Dividends or Other Earnings Paid on Equity Awards not Otherwise Reflected in Total Compensation for Covered Year Dividends or Other Earnings Paid on Equity Awards not Otherwise Reflected in Total Compensation for Covered Year [Member] Guarantor obligation Guarantor Obligations, Current Carrying Value Current fiscal year, writeoff Financing Receivable, Year One, Originated, Current Fiscal Year, Writeoff Derivative Instruments and Hedging Activities Disclosure [Abstract] Derivative Instruments and Hedging Activities Disclosure [Abstract] Effective interest rate Debt Instrument, Interest Rate, Effective Percentage Pledged Status [Domain] Pledged Status [Domain] Entity Address, Postal Zip Code Entity Address, Postal Zip Code Restatement Determination Date Restatement Determination Date Incremental common shares attributable to dilutive effect of conversion of preferred stock (in shares) Incremental Common Shares Attributable to Dilutive Effect of Conversion of Preferred Stock Provision for federal income taxes Provision for federal income taxes Provision for U.S. federal income taxes and effective tax rate Income Tax Expense (Benefit) Trading Securities Trading Assets, Excluding Debt and Equity Securities [Member] Other assets Other Assets Beginning Balance Ending Balance Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value Document Information [Line Items] Document Information [Line Items] Preferred stock, shares issued (in shares) Preferred Stock, Shares Issued Pension Adjustments Service Cost Pension Adjustments Service Cost [Member] Risk management derivatives designated as hedging instruments: Designated as Hedging Instrument [Member] Conversion price per share (in dollars per share) Convertible Stock, Conversion Price The price per share of the conversion of the convertible series 2004-1 preferred stock to Fannie Mae common stock. Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Single Vendor Primarily Consensus [Member] Primarily Consensus Risk-weighted assets Banking Regulation, Risk-Weighted Assets, Actual Offsetting [Abstract] Offsetting [Abstract] Single-family Single Family [Member] Compensation Actually Paid vs. Company Selected Measure Compensation Actually Paid vs. Company Selected Measure [Text Block] Tier 1 capital Banking Regulation, Tier 1 Risk-Based Capital [Abstract] Ten-year Constant Maturity U.S. Treasury Rate Ten-year Maturity U.S. Treasury Rate [Member] An index based on the average yield of a range of Treasury securities, adjusted to the equivalent of a 10-year maturity. Summary of Prior Period Adjustments Schedule of Error Corrections and Prior Period Adjustments [Table Text Block] All Trading Arrangements All Trading Arrangements [Member] Equity Awards Adjustments, Footnote Equity Awards Adjustments, Footnote [Text Block] Total Shareholder Return Vs Peer Group Total Shareholder Return Vs Peer Group [Text Block] Series I Series I Preferred Stock [Member] Outstanding Series I Preferred Stock. This stock has no par value, is non-participating, is non-voting and has a liquidation preference equal to the stated value per share. Commitments and Contingencies Commitments and Contingencies, Policy [Policy Text Block] Other Effective Income Tax Rate Reconciliation, Other Adjustments, Amount Deferred tax liabilities: Deferred Tax Liabilities, Gross [Abstract] Fee and other income Noninterest Income, Other Operating Income Total Capital Requirement Ratio (including Buffers) Banking Regulation, Adjusted Total Risk-Based Capital Ratio, Actual Banking Regulation, Adjusted Total Risk-Based Capital Ratio, Actual Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Disclosure [Abstract] Available Capital (Deficit) Ratio Banking Regulation, Excess (Deficit) Core Leverage Capital Ratio, Actual Banking Regulation, Excess (Deficit) Core Leverage Capital Ratio, Actual Net cash provided by (used in) operating activities Cash Provided by (Used in) Operating Activity, Including Discontinued Operation Contractual maturity term Debt Instrument, Term Total available-for-sale securities Available-for-sale securities Debt Securities, Available-for-Sale, Excluding Accrued Interest Loans in Mortgage Portfolio [Table] Loans In Mortgage Portfolio [Table] Schedule detailing Single-family and Multifamily mortgage loans, including loans held for investment and loans held for sale of Fannie Mae and Consolidated Trusts, as of the end of the period. In addition, we report the related allowance for loan losses for loans held for investment as of the end of the period. Sales Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales Preferred stock, stated value per share (in dollars per share) Preferred Stock, Par or Stated Value Per Share Net interest income Net contractual interest expense on interest-rate swaps Net interest income Interest Income (Expense), Operating Equity Valuation Assumption Difference, Footnote Equity Valuation Assumption Difference, Footnote [Text Block] PEO Total Compensation Amount PEO Total Compensation Amount Total Capital Requirement (including buffers) Banking Regulation, Tier 1 Risk-Based Capital, Actual Long-term Debt, Type [Axis] Long-Term Debt, Type [Axis] Derivative liabilities, gross amount Derivative Liability, Subject to Master Netting Arrangement, before Offset Trial Modification and Repayment Plans Trial Modification and Repayment Plans [Member] Trial Modification and Repayment Plans FHFA debt limit FHFA Debt Limit FHFA Debt Limit Restructured loans, subsequent default Financing Receivable, Restructured Loans Not Considered TDRs, Amortized Cost, Subsequent Default Financing Receivable, Restructured Loans Not Considered TDRs, Amortized Cost, Subsequent Default Equity Components [Axis] Equity Components [Axis] Non-Rule 10b5-1 Arrangement Adopted Non-Rule 10b5-1 Arrangement Adopted [Flag] Total liabilities, under master netting arrangements, amounts not offset in our consolidated balance sheets, financial statements Derivative Liability, Security Sold under Agreement to Repurchase, and Security Loaned, Subject to Master Netting Arrangement, Deduction of Financial Instrument Not Offset Reclassification adjustment for gains (losses) included in net loss, tax Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, Tax Number of reportable segments Number of Reportable Segments Net unamortized discount, fair value adjustments and other cost basis adjustments Debt Instrument, Unamortized Discount (Premium), Net Entity Address, State or Province Entity Address, State or Province Substandard Substandard [Member] Total interest income Interest and Dividend Income, Operating Special Mention Special Mention [Member] Financial Asset, Period Past Due [Domain] Financial Asset, Aging [Domain] Appraisal Appraisals [Member] An appraisal is a valuation techniques to estimate the fair value of a specific acquired property, other asset or collateral underlying a loan by a certified or licensed appraiser, in accordance with the Uniform Standards of Professional Appraisal Practice. Consolidations and Transfers of Financial Assets Consolidations And Transfers Of Financial Assets [Text Block] The entire disclosure for consolidation of the reporting entity. Provides users with an understanding of (1) the significant judgments and assumptions made by an enterprise in determining whether it must consolidate a VIE and/or disclose information about its involvement with a VIE, (2) the nature of restrictions on a consolidated VIE's assets reported by an enterprise in its statement of financial position, including the carrying amounts of such assets, (3) the nature of, and changes in, the risks associated with an enterprise's involvement with the VIE, and (4) how an enterprise's involvement with the VIE affects the enterprise's financial position, financial performance, and cash flows. The entire disclosure for a transferor's continuing involvement in financial assets that it has transferred in a securitization or asset-backed financing arrangement, the nature of any restrictions on assets reported by an entity in its statement of financial position that relate to a transferred financial asset (including the carrying amounts of such assets), how servicing assets and servicing liabilities are reported, and (for securitization or asset-backed financing arrangements accounted for as sales) when a transferor has continuing involvement with the transferred financial assets and transfers of financial assets accounted for as secured borrowings, how the transfer of financial assets affects an entity's financial position, financial performance, and cash flows. Total loans held for investment, fair value Total multifamily mortgage loans held for investment, at amortized cost Loans Receivable, Fair Value Disclosure Other Senior Floating Other Debt [Member] Senior floating other with interest rates that are subject to adjustment represents debt instruments with original contractual maturities greater than one year that is not included in other senior floating rate debt categories. Includes a portion of structured debt instruments that is reported at fair value. Senior floating debt takes priority over other debt instruments sold by the company. In the event the company goes bankrupt, senior floating debt holders receive priority for repayment prior to junior or unsecured general creditors. Affordable Housing Program obligation Affordable Housing Program Obligation, Portion Affordable Housing Program Obligation, Portion Individual: Individual [Axis] Document Annual Report Document Annual Report Maximum Exposure to Loss Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount Professional services, technology, and occupancy Professional and Contract Services Expense Forgone Recovery, Explanation of Impracticability Forgone Recovery, Explanation of Impracticability [Text Block] Minimum Capital Requirement Banking Regulation, Tier 1 Risk-Based Capital, Capital Adequacy, Minimum Three fiscal years before Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year Entity Interactive Data Current Entity Interactive Data Current Two fiscal years, writeoff Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year, Writeoff Interest income: Interest and Dividend Income, Operating [Abstract] Securities purchased under agreements to resell or similar arrangements, under master netting arrangements, amounts not offset in our consolidated balance sheets, collateral Security Purchased under Agreement to Resell, Subject to Master Netting Arrangement, Collateral, Obligation to Return Security Not Offset Total non-interest expense Total non-interest expense Noninterest Expense Securities purchased under agreements to resell Federal Funds Sold and Securities Borrowed or Purchased under Agreements to Resell, Fair Value Disclosure Investments in securities, at fair value Marketable Securities Payment Deferral Payment Deferral [Member] Transfers of Financial Assets Transfers and Servicing of Financial Assets, Policy [Policy Text Block] Allowance for Credit Losses Allowance for Credit Losses [Text Block] Current fiscal year Financing Receivable, Year One, Originated, Current Fiscal Year Series D Series D Preferred Stock [Member] Entity Central Index Key Entity Central Index Key Southwest Southwest United States [Member] Southwest includes AZ, AR, CO, KS, LA, MO, NM, OK, TX, UT PEO Name PEO Name Long-Term Debt by Year of Maturity Schedule of Maturities of Long-Term Debt [Table Text Block] Error Correction [Table] Error Correction [Table] Prior Year End Fair Value of Equity Awards Granted in Any Prior Year that Fail to Meet Applicable Vesting Conditions During Covered Year Prior Year End Fair Value of Equity Awards Granted in Any Prior Year that Fail to Meet Applicable Vesting Conditions During Covered Year [Member] Financial Instruments [Line Items] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Allowance for mortgage insurance receivable Allowance for Mortgage Insurance Receivable The amount of the valuation allowance recorded as of the balance sheet date pertaining to the specified mortgage insurance receivable for which an assessment was made that a portion of such mortgage insurance receivable will not be collected. Foreign currency Currency Swap [Member] Credit Quality Indicators Financing Receivable Credit Quality Indicators [Table Text Block] Senior preferred stock, liquidation preference Senior Preferred Stock, Liquidation Preference, Value Senior Preferred Stock, Liquidation Preference, Value Outstanding Aggregate Erroneous Compensation Amount Outstanding Aggregate Erroneous Compensation Amount Beginning Balance Ending Balance Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability Value Minimum Capital Requirement Banking Regulation, Tier 1 Leverage Capital, Capital Adequacy, Minimum Segment Results [Table] Schedule of Segment Reporting Information, by Segment [Table] Pool mortgage insurance coverage risk in force Pool Mortgage Insurance Coverage Risk in Force Represents our maximum potential loss recovery under the applicable pool mortgage insurance policies. Other Mortgage-Backed Securities, Other [Member] Common stock warrant exercise price (in dollars per share) Class of Warrant or Right, Exercise Price of Warrants or Rights Exercise Price Award Exercise Price Entity Filer Category Entity Filer Category Minimum Capital Ratio Requirement Banking Regulation, Tier 1 Risk-Based Capital Ratio, Capital Adequacy, Minimum Class of Stock [Domain] Class of Stock [Domain] U.S. federal statutory corporate tax rate Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent Partnership and other equity investments Deferred Tax Assets, Equity Method Investments Hedged asset, total basis adjustments Hedged Asset, Fair Value Hedge, Cumulative Increase (Decrease) Fair Value Option, Disclosures [Table] Fair Value Option, Disclosures [Table] Acquired property, net Real Estate Acquired Through Foreclosure Total mortgage loans Financing Receivable, before Allowance for Credit Loss Available Capital (Deficit) Ratio Banking Regulation, Tier One Risk-Based Capital Ratio, Excess (Deficit), Actual Banking Regulation, Tier One Risk-Based Capital Ratio, Excess (Deficit), Actual Vesting Date Fair Value of Equity Awards Granted and Vested in Covered Year Vesting Date Fair Value of Equity Awards Granted and Vested in Covered Year [Member] Entity Address, Address Line One Entity Address, Address Line One Loans Held for Sale Financing Receivable, Held-for-Sale [Policy Text Block] Accumulated Other Comprehensive Income AOCI Attributable to Parent [Member] Internal Credit Assessment [Axis] Internal Credit Assessment [Axis] Interest accruals on derivative hedging instruments Interest Accruals On Hedging Instruments Interest Accruals On Hedging Instruments Internal Credit Assessment [Domain] Internal Credit Assessment [Domain] Derivative Instruments Derivative Instruments and Hedging Activities Disclosure [Text Block] Schedule of Preferred Stock Schedule of Stock by Class [Table Text Block] Fair Value as of Grant Date Award Grant Date Fair Value Table Footnote Table Footnote [Abstract] Represents a tabular schedule for the footnotes to a table. Loans seriously delinquent, percentage by unpaid principal balance Loans Seriously Delinquent, Unpaid Principal Balance, Percentage by Category Represents the percentage of loans that were seriously delinquent greater than 60 days. The percentage is calculated based on the unpaid principal balance of loans that were seriously delinquent divided by the aggregate unpaid principal balance of loans for each category included in our guaranty book of business. Long-Term Debt Schedule of Long-Term Debt Instruments [Table Text Block] Salaries and employee benefits Labor and Related Expense Minimum Capital Ratio Requirement Banking Regulation, Tier 1 Leverage Capital Ratio, Capital Adequacy, Minimum Total assets, gross amount offset Derivative Asset, Security Purchased under Agreement to Resell, and Security Borrowed, Subject to Master Netting Arrangement, Liability Offset Related Parties [Line Items] Related Party Transaction [Line Items] Top five non-depository servicers Group of Largest Mortgage Servicers including Affiliates [Member] Represents the number of our largest mortgage servicers, including their affiliates. Total Capital Requirement Ratio (including Buffers) Banking Regulation, Tier 1 Risk-Based Capital Ratio, Actual Internal Model Internal Model [Member] Internal Model is a valuation technique to estimate the fair value of loans, acquired property and other assets using the value of the underlying collateral. The inputs into this internal model include property level data such as prior sales prices, tax assessment values, property characteristics, and historical foreclosure sales data. Derivatives use an internal model that is based on market data adjusted for market movement. Deferred income tax expense (benefit) Deferred Income Taxes and Tax Credits Fair Value Measurement Inputs and Valuation Techniques Fair Value Measurement Inputs and Valuation Techniques [Table Text Block] Long-term debt Debt: Long-Term Debt, Fair Value Changed Peer Group, Footnote Changed Peer Group, Footnote [Text Block] Counterparty Name [Domain] Counterparty Name [Domain] Financing Receivable, Nonaccrual Financing Receivable, Nonaccrual [Table Text Block] Financial Guarantees Guarantees [Text Block] Broker-Dealer, Net Capital Requirement, SEC Regulation [Abstract] Broker-Dealer, Net Capital Requirement, SEC Regulation [Abstract] Securities purchased under agreements to resell, under master netting arrangement, amounts not offset in our consolidated balance sheets, financial instruments Security Purchased under Agreement to Resell, Subject to Master Netting Arrangement, Deduction of Financial Instrument Not Offset Adjustment To PEO Compensation, Footnote Adjustment To PEO Compensation, Footnote [Text Block] Arch Capital Group Ltd. Arch Capital Group Ltd. [Member] Represents one of our largest mortgage insurer counterparties, Arch Capital Group Ltd. Title Trading Arrangement, Individual Title Peer Group Total Shareholder Return Amount Peer Group Total Shareholder Return Amount Restructured loans, paid off, repurchased or sold during period Financing Receivable, Modified in Period, Loans Paid Off, Repurchased Or Sold During Period Financing Receivable, Modified in Period, Loans Paid Off, Repurchased Or Sold During Period Senior floating Senior Floating Debt [Member] Senior debt instruments with interest rates that are subject to periodic adjustment based on an index or formula with original contractual maturities greater than one year. Senior floating rate debt takes priority over other debt instruments sold by the company. In the event the company goes bankrupt, senior floating rate debt holders receive priority for repayment prior to junior or unsecured general creditors. Non-PEO NEO Non-PEO NEO [Member] Related allowance Financing Receivable, Transfer to Held-for-Sale, Allowance for Credit Loss, Expense Reversal Preferred stock, annual dividend rate Preferred Stock, Dividend Rate, Percentage Net impact of hedged mortgage assets and debt Gain (Loss) on Hedging Activity All Award Types Award Type [Domain] Net revenues Revenues, Net of Interest Expense Series S Series S Preferred Stock [Member] 7.75% fixed to floating rate non-cumulative Preferred Series S Stock. Advances to lenders Payments For Advances To Lenders Advances to lenders represent payments of cash in exchange for the receipt of mortgage loans from lenders in a transfer that is accounted for as a secured lending arrangement. Equity Awards Adjustments Equity Awards Adjustments [Member] Pension Benefits Adjustments, Footnote Pension Benefits Adjustments, Footnote [Text Block] Compensation Amount Outstanding Recovery Compensation Amount Consensus Consensus Without Inputs [Member] Valuation methodology used to estimate the fair value of certain securities, loans and debt. This methodology uses multiple vendor prices (active market participants) to estimate fair value. These fair values are not validated at the security level therefore inputs have not been disclosed. Recovery of Erroneously Awarded Compensation Disclosure [Line Items] Estimate of fair value Estimate of Fair Value Measurement [Member] Commitments to Purchase and Sell Mortgage Loans and Securities Commitments to Purchase and Sell Mortgage Loans and Securities [Policy Text Block] Disclosure of accounting policy for commitments to purchase and sell mortgage- backed securities and to purchase single-family and multifamily mortgage loans. MNPI Disclosure Timed for Compensation Value MNPI Disclosure Timed for Compensation Value [Flag] Derivative assets, net amount presented in our consolidated balance sheets Net derivatives Derivative Asset, Subject to Master Netting Arrangement, before Offset of Collateral Fair Value Inputs, Quantitative Information [Line Items] Fair Value Inputs, Quantitative Information [Line Items] Fair Value, Option, Quantitative Disclosures [Line Items] Minimum Capital Requirement Banking Regulation, Adjusted Total Risk-Based Capital, Capital Adequacy, Minimum Banking Regulation, Adjusted Total Risk-Based Capital, Capital Adequacy, Minimum Purchase of HFI loans: Financing Receivable, Purchase Weighted-Average Interest Rate Reduction Financing Receivable, Restructured Loans Not Considered TDRs, Weighted-Average Interest Rate Reduction Financing Receivable, Restructured Loans Not Considered TDRs, Weighted-Average Interest Rate Reduction Financing Receivable, Past Due [Line Items] Financing Receivable, Past Due [Line Items] Derivative liabilities, under master netting arrangements, amounts not offset in our consolidated balance sheets, financial instruments Derivative Liability, Subject to Master Netting Arrangement, Deduction of Financial Instrument Not Offset Cash, including restricted cash Cash and Restricted Cash, Fair Value Disclosure This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item includes currency on hand as well as demand deposits with banks or financial institutions. It also includes other kinds of accounts that have the general characteristics of demand deposits in that the Company may deposit additional funds at any time and also effectively may withdraw funds at any time without prior notice or penalty. Cash equivalents, excluding items classified as marketable securities, include short-term, highly liquid investments that are both readily convertible to known amounts of cash, and so near their maturity that they present minimal risk of changes in value because of changes in interest rates. Generally, only investments with original maturities of three months or less qualify under that definition. Original maturity means original maturity to the entity holding the investment. For example, both a three-month US Treasury bill and a three-year Treasury note purchased three months from maturity qualify as cash equivalents. However, a Treasury note purchased three years ago does not become a cash equivalent when its remaining maturity is three months. The carrying amounts of cash and cash equivalent items which are restricted as to withdrawal or usage. Restrictions may include legally restricted deposits held as compensating balances against borrowing arrangements, contracts entered into with others, or entity statements of intention with regard to particular deposits; however, time deposits and short-term certificates of deposit are not generally included in legally restricted deposits. Excludes compensating balance arrangements that are not agreements which legally restrict the use of cash amounts shown on the balance sheet. This element is for unclassified presentations; for classified presentations there is a separate and distinct element. Tax credits, amount Effective Income Tax Rate Reconciliation, Tax Credit, Amount [Abstract] Accumulated other comprehensive income Accumulated Other Comprehensive Income (Loss), Net of Tax 2026 Long-Term Debt, Maturity, Year One Financial Instruments [Domain] Fair Value, Option, Eligible Item or Group [Domain] Financial Instruments [Domain] Purchases Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases 2030 Long-Term Debt, Maturity, Year Five Total Capital Requirement (including buffers) Banking Regulation, Adjusted Total Capital, Actual Banking Regulation, Adjusted Total Capital, Actual Aggregate Pension Adjustments Service Cost Aggregate Pension Adjustments Service Cost [Member] Other expenses, net Other Noninterest Expense, Excluding Change In Expected Credit Enhancement Recoveries Other Noninterest Expense, Excluding Change In Expected Credit Enhancement Recoveries Proceeds from repayments Proceeds from Principal Repayment, Loan and Lease, Held-for-Investment Other adjustments, percent Effective Income Tax Rate Reconciliation, Other Reconciling Items, Percent [Abstract] Minimum Minimum [Member] Partnership interest Partnership Interest [Member] Accounts, Notes, Loans and Financing Receivable [Line Items] Accounts, Notes, Loans and Financing Receivable [Line Items] Company Selected Measure Name Company Selected Measure Name Fair Value Measurement [Domain] Fair Value Measurement [Domain] Minimum Capital Requirement Banking Regulation, Total Risk-Based Capital, Capital Adequacy, Minimum Short-Term and Long-Term Debt Debt Disclosure [Text Block] Aggregate Available Trading Arrangement, Securities Aggregate Available Amount Stock Appreciation Rights (SARs) Stock Appreciation Rights (SARs) [Member] Net income attributable to common stockholders, diluted Net Income (Loss) Available to Common Stockholders, Diluted Loans 90 Days or More Delinquent and Accruing Interest Financing Receivable, 90 Days or More Past Due, Still Accruing Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Diluted (in shares) Weighted Average Number of Shares Outstanding, Diluted Short-term debt of Fannie Mae, weighted-average interest rate Short-Term Debt, Weighted Average Interest Rate, at Point in Time Segment Reporting Segment Reporting, Policy [Policy Text Block] Total liabilities, under master netting arrangements, amounts not offset in our consolidated balance sheets, collateral Derivative Liability, Security Sold under Agreement to Repurchase, and Security Loaned, Subject to Master Netting Arrangement, Collateral, Right to Reclaim Security Not Offset Non-GAAP Measure Description Non-GAAP Measure Description [Text Block] Reconciliation of Assets from Segment to Consolidated [Table] Reconciliation of Assets from Segment to Consolidated [Table] Derivative [Table] Derivative [Table] Entity Small Business Entity Small Business Income Tax Disclosure [Abstract] Income Tax Disclosure [Abstract] Preferred stock, shares outstanding (in shares) Preferred Stock, Shares Outstanding Document Transition Report Document Transition Report Other Senior Fixed Other Debt [Member] Senior fixed other represent debt instruments with original contractual maturities greater than one year that are not included in other senior fixed rate debt categories. Includes a portion of structured debt instruments that is reported at fair value. Senior fixed rate debt takes priority over other debt instruments sold by the company. In the event the company goes bankrupt, senior fixed rate debt holders receive priority for repayment prior to junior or unsecured general creditors. Schedules of Concentration of Risk, by Risk Factor Schedules of Concentration of Risk, by Risk Factor [Table Text Block] Long-term Debt Long-Term Debt [Member] Underlying Securities Award Underlying Securities Amount Equity Component [Domain] Equity Component [Domain] Document Period End Date Document Period End Date Income Taxes Income Tax Disclosure [Text Block] Awards Close in Time to MNPI Disclosures, Table Awards Close in Time to MNPI Disclosures [Table Text Block] Total liabilities, gross amount offset Derivative Liability, Security Sold under Agreement to Repurchase, and Security Loaned, Subject to Master Netting Arrangement, Asset Offset Derivative liability Derivative, Net Liability Position, Aggregate Fair Value Closed portfolio, designated UPB Hedged Asset, Fair Value Hedge, Portfolio Layer Method, Hedged Layer, Amount Series O Series O Preferred Stock [Member] Outstanding Series O Preferred Stock. This stock has no par value, is non-participating, is non-voting and has a redemption price of $50 to $52.50 depending on the year of redemption. Derivative assets, net amount Derivative Asset, Including Not Subject to Master Netting Arrangement, after Offset and Deduction Beginning balance Ending balance Equity, Including Portion Attributable to Noncontrolling Interest Risks and Uncertainties [Abstract] Risks and Uncertainties [Abstract] Total mortgage loans Mortgage Loans on Real Estate, Commercial and Consumer, Net Document Type Document Type Significant Unobservable Inputs (Level 3) Fair Value, Inputs, Level 3 [Member] Schedule of Assets by Segment Reconciliation of Assets from Segment to Consolidated [Table Text Block] Name Outstanding Recovery, Individual Name Loss Contingencies [Table] Loss Contingencies [Table] Product and Service [Axis] Product and Service [Axis] Service Providers [Axis] Service Providers [Axis] Represents service providers by type. Leverage capital: Banking Regulation, Leverage Capital [Abstract] Banking Regulation, Leverage Capital Litigation Status [Domain] Litigation Status [Domain] Retained interests: principal and interest received Cash Flows Between Transferor and Transferee, Beneficial Interest Statistical Measurement [Axis] Statistical Measurement [Axis] Litigation interest Litigation Settlement Interest Aggregate Erroneous Compensation Amount Aggregate Erroneous Compensation Amount Total available funding from treasury pursuant to the senior preferred stock agreement Total Available Funding From Treasury Pursuant To The Senior Preferred Stock Agreement Represents total available funding from U.S. Treasury pursuant to the senior preferred stock agreement after 2012 if we do not have a positive net worth as of December 31, 2012. In the event we have a positive net worth as of December 31, 2012, then the amount of funding available after 2012 under the amended senior preferred stock purchase agreement will depend on the size of that positive net worth relative to the cumulative draws for net worth deficiencies attributable to periods during 2010, 2011, and 2012, as follows: 1) If our positive net worth as of December 31, 2012 is less than the cumulative draws for net worth deficiencies attributable to periods during 2010, 2011, and 2012, then the amount of available funding will be $124.8 billion less our positive net worth as of December 31, 2012. 2) If our positive net worth as of December 31, 2012 is greater than the cumulative draws for net worth deficiencies attributable to periods during 2010, 2011, and 2012, then the amount of available funding will be $124.8 billion less the cumulative draws attributable to periods during 2010, 2011, and 2012. Peer Group Issuers, Footnote Peer Group Issuers, Footnote [Text Block] Available Capital (Deficit) Banking Regulation, Adjusted Total Risk-Based Capital, Excess (Deficit), Actual Banking Regulation, Adjusted Total Risk-Based Capital, Excess (Deficit), Actual Net income attributable to common stockholders, basic Net Income (Loss) Available to Common Stockholders, Basic Credit enhancement expense Credit Enhancement Expense Credit Enhancement Expense Legislative assessments Legislative assessments Legislative Assessment Expense Legislative Assessment Expense Guarantor Obligations, Nature [Domain] Guarantor Obligations, Nature [Domain] Schedule of Derivative Fair Value Gain (Loss), Net Derivative Instruments, Gain (Loss) [Table Text Block] Derivatives, Hedging Derivatives, Methods of Accounting, Hedging Derivatives [Policy Text Block] Multifamily Multifamily Segment [Member] Multifamily Segment Quoted Prices in Active Markets for Identical Assets (Level 1) Fair Value, Inputs, Level 1 [Member] Beginning balance (shares) Ending balance (shares) Senior preferred stock outstanding (in shares) Shares, Outstanding Core capital (statutory) Banking Regulation, Core Leverage Capital [Abstract] Banking Regulation, Core Leverage Capital Securities purchased under agreements to resell or similar arrangements, net amount presented in our consolidated balance sheets Securities Purchased under Agreements to Resell, Not Subject to Master Netting Arrangement Insurance Service Provider Concentration Risk Insurance Service Provider Concentration Risk [Member] Reflects the concentration risk of mortgage insurance coverage by mortgage insurers as a percentage. Preferred stock, redemption price (in dollars per share) Preferred Stock, Redemption Price Per Share Related Party Transaction [Table] Related Party Transaction [Table] Diluted (in dollars per share) Earnings Per Share, Diluted Multifamily Multifamily (less than) Multifamily [Member] Zero-coupon debt Zero-Coupon Debt [Member] Represents a debt security that doesn't pay interest (a coupon)but is traded/sold at a deep discount, rendering profit at maturity when the bond is redeemed for its full face value. Loans held for sale, at lower of cost or fair value Financing Receivable, Held-for-Sale Treasury stock at cost (in shares) Treasury Stock, Common, Shares Consolidation Items [Domain] Consolidation Items [Domain] Weighted average number of shares, contingently issuable (in shares) Weighted Average Number of Shares, Contingently Issuable Investments, Debt and Equity Securities [Abstract] Investments, Debt and Equity Securities [Abstract] Purchases Payment for Acquisition, Loan, Held-for-Investment Auditor Location Auditor Location Radian Guaranty, Inc. Radian Guaranty, Inc [Member] Represents one of our largest mortgage insurer counterparties, Radian Guaranty, Inc. Unconsolidated VIEs Variable Interest Entity, Not Primary Beneficiary [Member] Guaranty Book of Business Guaranty Book of Business [Member] Represents the sum of the unpaid principal balance of: (1) mortgage loans held in our mortgage portfolio; (2) Fannie Mae MBS held in our mortgage portfolio; (3) Fannie Mae MBS held by third parties; and (4) other credit enhancements that we provide on mortgage assets. It excludes non-Fannie Mae mortgage-related securities held in our investment portfolio for which we do not provide a guaranty. Financing Receivable Portfolio Segment [Axis] Financing Receivable Portfolio Segment [Axis] Two-year Constant Maturity U.S. Treasury Rate Two-year Maturity U.S. Treasury Rate [Member] An index based on the average yield of a range of Treasury securities, adjusted to the equivalent of a two-year maturity. Schedule of Risk in Force Mortgage Insurance Coverage Schedule Of Risk In Force Mortgage Insurance Coverage [Table Text Block] Tabular disclosure of risk in force mortgage insurance coverage. Federal income taxes, net of refunds Income Taxes Paid, Net Total assets, under the master netting arrangements, not offset in our consolidated balance sheets, financial instruments Derivative Asset, Security Purchased under Agreement to Resell, and Security Borrowed, Subject to Master Netting Arrangement, Deduction of Financial Instrument Not Offset OTC risk management derivatives Over-the-Counter [Member] Mortgage commitments to purchase whole loans Mortgage Commitments to Purchase Whole Loans [Member] Represent forward contract/commitments to purchase single-family mortgage whole loans. Outstanding debt Debt, unpaid principal balance Long-Term Debt, Gross Entity Well-known Seasoned Issuer Entity Well-known Seasoned Issuer Mortgage insurance coverage risk in force Mortgage Insurance Coverage Risk In Force Mortgage Insurance Coverage 'risk in force' represents our maximum potential loss recovery under the applicable mortgage insurance policies. Changes in net unrealized losses on available-for-sale securities, net of taxes OCI, Debt Securities, Available-for-Sale, Unrealized Holding Gain (Loss), before Adjustment, after Tax 60 days delinquent (percentage of conventional loans) Number of Loans 60 to 89 Days Past Due, Percentage Represents the percentage of loans that are 60 to 89 days past due. Calculated based on the number of loans in the delinquency bucket indicated, divided by the total number of loans in the respective category. Five Major Lenders Five Major Lenders [Member] Five Major Lenders Regulatory Capital Classification Measures Schedule of Compliance with Regulatory Capital Requirements under Banking Regulations [Table Text Block] Net change in servicer advances Increase (decrease) in servicer advances Increase (decrease) in servicer advances Total loans held for investment Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss Restructured loans, percent of total financing receivable (* less than) Financing Receivable, Restructured Loans Not Considered TDRs, Percent of Total Financing Receivable Financing Receivable, Modified In Period, To Total Financing Receivables, Percentage Expiration Date Trading Arrangement Expiration Date Total liabilities, net amount Derivative Liability, Security Sold under Agreement to Repurchase, and Security Loaned, Including Not Subject to Master Netting Arrangement, after Offset and Deduction One fiscal year, writeoff Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year, Writeoff Dealer Mark and Discounted Cash Flow Dealer Mark and Discounted Cash Flow [Member] Dealer Mark and Discounted Cash Flow Geographic Concentration Risk Geographic Concentration Risk [Member] Compensation Actually Paid vs. Net Income Compensation Actually Paid vs. Net Income [Text Block] Less than or equal to 80% Estimated Mark To Market Loan To Value Ratio Less Than or Equal to 80 Percent [Member] Represents the recorded investment in loans with an estimated mark-to-market loan-to-value ratio less than or equal to 80%. Available Capital (Deficit) Banking Regulation, Excess (Deficit) Tier One Leverage Capital, Actual Banking Regulation, Excess (Deficit) Tier One Leverage Capital, Actual Entity Current Reporting Status Entity Current Reporting Status Receivables [Abstract] Receivables [Abstract] Derivative [Line Items] Derivative [Line Items] Awards Close in Time to MNPI Disclosures Awards Close in Time to MNPI Disclosures [Table] Schedule of Risk Characteristics Guaranty Book of Business Schedule Of Risk Characteristics Guaranty Book Of Business [Table Text Block] Tabular disclosure of certain higher risk characteristics of our single-family conventional and total multifamily guarantee book of business. Consolidated Entities [Domain] Consolidated Entities [Domain] U.S. federal statutory corporate tax rate Effective Income Tax Rate Reconciliation at Federal Statutory Income Tax Rate, Amount Mortgage loans received by consolidated trusts to satisfy advances to lenders Net Transfers From Advances to Lenders to Loans Held for Investment of Consolidated Trusts1 Represents net transfers of MBS securities created as a result of the Early Lender sale program to loans held for investment of consolidated trusts. Advances to lenders Advance to Lender Advance to Lender Derivative liabilities, gross Derivative Liability, Gross Liability Including Not Subject to Master Netting Arrangement Transaction [Domain] Transaction [Domain] Total liabilities, net amount presented in our consolidated balance sheets Derivative Liability, Security Sold under Agreement to Repurchase, and Security Loaned, Subject to Master Netting Arrangement, after Offset Financial Instrument [Axis] Eligible Item or Group for Fair Value Option [Axis] Financial Instrument [Axis] Deferred tax assets: Deferred Tax Assets, Gross [Abstract] Statement of Financial Position [Abstract] Statement of Financial Position [Abstract] Executive Category: Executive Category [Axis] Nonaccrual Loans and Allowance for Loan Losses Financing Receivable [Policy Text Block] Payments to redeem debt Repayments of Debt Comprehensive income: Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest [Abstract] LIHTC investments Effective Income Tax Rate Reconciliation, Tax Credit, Investment, Amount Current Fiscal Year End Date Current Fiscal Year End Date Payment Delay and Term Extension Payment Deferral and Extended Maturity [Member] Payment Deferral and Extended Maturity Loans in Mortgage Portfolio Schedule of Accounts, Notes, Loans and Financing Receivable [Table Text Block] Schedule of Guarantor Obligations Schedule of Guarantor Obligations [Table Text Block] Derivatives liabilities at fair value Derivative liabilities at fair value Derivative Liability Four fiscal years before Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year Other income (expense), net Other expense, net Other Noninterest Expense Walker & Dunlop, LLC Walker & Dunlop, LLC [Member] Represents one of our largest mortgage servicer counterparties, Walker & Dunlop, LLC Equity Awards Adjustments, Excluding Value Reported in Compensation Table Equity Awards Adjustments, Excluding Value Reported in the Compensation Table [Member] Loan Restructuring Modification [Axis] Loan Restructuring Modification [Axis] Pass Pass [Member] Risk management derivatives Interest Rate Contract [Member] Fair value of the warrant at issuance Adjustments to Additional Paid in Capital, Warrant Issued Derivative asset, not subject to master netting arrangement Derivative Asset, Not Subject to Master Netting Arrangement Greater than 100% Estimated Mark To Market Loan To Value Ratio Greater Than 100 Percent, Loans Recorded Investment [Member] Estimated Mark To Market Loan To Value Ratio Greater Than 100 Percent, Loans Recorded Investment [Member] Recurring Changes in Fair Value Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block] Preferred stock, redemption terms Preferred Stock, Redemption Terms Weighted-average common shares outstanding: Weighted Average Number of Shares Outstanding, Diluted [Abstract] Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] Fair Value of Financial Instruments [Table] Fair Value, by Balance Sheet Grouping [Table] 2027 Long-Term Debt, Maturity, Year Two Aging Analysis Financing Receivable, Past Due [Table Text Block] Greater than 100% (less than) Estimated Mark to Market Loan to Value Ratio Greater Than One Hundred Percent [Member] Represents the percentage of loans with an estimated mark-to-market loan-to-value ratio greater than 100%. Interest-only securities Deferred Tax Assets, Investments Net cash provided by (used in) financing activities Cash Provided by (Used in) Financing Activity, Including Discontinued Operation Measure: Measure [Axis] Valuation Approach and Technique [Axis] Valuation Approach and Technique [Axis] Tier 1 capital Banking Regulation, Tier 1 Leverage Capital [Abstract] Mortgage commitment derivatives Mortgage Commitment Derivatives [Member] Represents a forward-based arrangement to purchase or sell mortgages-related securities and to purchase single-family mortgages in the secondary market. Pay vs Performance Disclosure, Table Pay vs Performance [Table Text Block] Total capital (statutory) Banking Regulation, Total Capital [Abstract] Forgone Recovery due to Violation of Home Country Law, Amount Forgone Recovery due to Violation of Home Country Law, Amount Entity Tax Identification Number Entity Tax Identification Number Advances to lenders Advances, Fair Value Disclosure Preferred stock covenant maximum fair market value of assets and properties per transaction Preferred Stock Covenant Maximum Fair Market Value of assets and properties per transaction Preferred Stock Covenant Maximum Fair Market Value of assets and properties per transaction or series of transactions in which Fannie Mae may sell without written consent of Treasury. Retained interest: fair value Fair Value Securities Retained Unconsolidated Portfolio Securitization Trusts Represents the fair value of securities retained in unconsolidated portfolio securitization trusts as of the period end. Schedule of Unconsolidated Variable Interest Entities Schedule of Variable Interest Entities [Table Text Block] Audit Information [Abstract] Audit Information [Abstract] Net Derivatives Derivative [Member] Net transfers from mortgage loans of Fannie Mae to mortgage loans of consolidated trusts Transfers From Loans Held For Investment Of Parent Company To Loans Held For Investment Of Consolidated Trusts Represents net transfers to (from) mortgage loans held for investment of consolidated trusts from (to) mortgage loans held for investment of Fannie Mae. Common stock, shares issued (in shares) Common Stock, Shares, Issued 2029 Long-Term Debt, Maturity, Year Four Schedule of Assumptions for Fair Value as of Balance Sheet Date of Assets or Liabilities that relate to Transferor's Continuing Involvement [Table] Qualitative and Quantitative Information, Transferor's Continuing Involvement [Table] Allowance for Loan Losses [Roll Forward] Allowance for Loan and Lease Losses [Roll Forward] Agency Mortgage-Backed Security, Issued by US Government-Sponsored Enterprise [Member] Entity Public Float Entity Public Float Trading Arrangement: Trading Arrangement [Axis] Total Shareholder Return Amount Total Shareholder Return Amount Proportional amortization, net of other tax benefits, on LIHTC investments Effective Income Tax Rate Reconciliation, Proportional Amortization on Investments, Net of Other Tax Benefits, Percent Effective Income Tax Rate Reconciliation, Proportional Amortization on Investments, Net of Other Tax Benefits, Percent Loss Contingencies [Line Items] Loss Contingencies [Line Items] Real Estate, Type of Property [Axis] Real Estate, Type of Property [Axis] Securities Purchased Under Agreements to Resell Repurchase and Resale Agreements Policy [Policy Text Block] Series E Series E Preferred Stock [Member] Netting Arrangements Netting Arrangements [Text Block] The entire disclosure for balance sheet offsetting/netting arrangements. Securities purchased under agreements to resell (includes $18,425 and $14,899, respectively, related to consolidated trusts) Securities purchased under agreements to resell Securities Purchased under Agreements to Resell Total risk management derivatives portfolio Total risk management derivatives portfolio [Member] Total risk management derivatives portfolio Available Capital (Deficit) Banking Regulation, Common Equity Tier One Risk-Based Capital, Excess (Deficit), Actual Banking Regulation, Common Equity Tier One Risk-Based Capital, Excess (Deficit), Actual Available Capital (Deficit) Ratio Banking Regulation, Total Risk-Based Capital Ratio, Excess (Deficit), Actual Banking Regulation, Total Risk-Based Capital Ratio, Excess (Deficit), Actual Mortgage-related securities Collateralized Mortgage-Backed Securities [Member] Mortgage Loans Financing Receivables [Text Block] Available Capital (Deficit) Ratio Banking Regulation, Common Equity Tier One Risk-Based Capital Ratio, Excess (Deficit), Actual Banking Regulation, Common Equity Tier One Risk-Based Capital Ratio, Excess (Deficit), Actual Senior Fixed Senior Fixed Debt [Member] Senior fixed rate debt instruments with an original contractual maturity of greater than one year. Senior fixed rate debt takes priority over other debt securities sold by the company. In the event the company goes bankrupt, senior fixed rate debt holders receive priority for repayment prior to junior or unsecured general creditors. Net trading gains (losses) Debt Securities, Trading, Gain (Loss) Fair Value by Asset Class [Domain] Asset Class [Domain] Statement [Line Items] Statement [Line Items] Payment Delay, Term Extension, Interest Rate Reduction and Other Payment Delay, Term Extension, Interest Rate Reduction, and Other Payment Deferral, Extended Maturity, and Contractual Interest Rate Reduction [Member] Payment Deferral, Extended Maturity, and Contractual Interest Rate Reduction Hedged asset, carrying amount Hedged Asset, Fair Value Hedge Rule 10b5-1 Arrangement Adopted Rule 10b5-1 Arrangement Adopted [Flag] Preferred stock, covenant, maximum mortgage assets Preferred Stock, Covenant, Maximum Mortgage Assets The maximum mortgage assets amount, as of the end of the current period, allowed per the covenant in the Senior Preferred Stock Agreement. Common Stock Common Stock [Member] Issues Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Issuances Summary Of Stock Purchase Agreement Summary Of Stock Purchase Agreement [Table Text Block] Summary Of Stock Purchase Agreement Interest Rate Risk On Held-for-Investment Mortgage Loan Interest Rate Risk On Held-for-Investment Mortgage Loan [Member] Interest rate risk on held for investment mortgage loan Securities purchased under agreements to resell or similar arrangements, gross amount offset Security Purchased under Agreement to Resell, Subject to Master Netting Arrangement, Liability Offset Financial Guarantees and Maximum Recovery [Line Items] Financial Guarantees and Maximum Recovery [Line Items] [Line Items] for Financial Guarantees and Maximum Recovery [Table] Treasury’s Capital Magnet Fund Treasury Capital Management Fund [Member] Treasury Capital Management Fund Summary of Significant Accounting Policies Significant Accounting Policies [Text Block] Statistical Measurement [Domain] Statistical Measurement [Domain] Amortized cost Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, before Allowance for Credit Loss Underlying Asset Class [Axis] Underlying Asset Class [Axis] Short-term debt: Short-Term Debt, Fair Value Southeast Southeast United States [Member] Southeast includes AL, DC, FL, GA, KY, MD, NC, MS, SC, TN, VA, WV Interest income recognized, nonaccrual loans Financing Receivable, Nonaccrual, Interest Income Related Party Transaction [Axis] Related Party Transaction [Axis] Long-term debt, weighted-average interest rate Long-Term Debt, Weighted Average Interest Rate, at Point in Time Judicial Ruling Judicial Ruling [Member] Real Estate [Domain] Real Estate [Domain] Asset Class [Axis] Asset Class [Axis] Valuation Approach and Technique [Domain] Valuation Approach and Technique [Domain] Tax Jurisdiction of Domicile [Extensible Enumeration] Tax Jurisdiction of Domicile [Extensible Enumeration] Debt Debt, Policy [Policy Text Block] One fiscal year before Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year 80.01% to 90% Original Loan to Value Ratio, 80.01% to 90% [Member] Original Loan to Value Ratio, 80.01% to 90% Valuation (gains) losses Valuation Loss (Gain) Includes the following non-cash items that flow through Investment gains (losses): (1) lower cost or market adjustment on whole loans; (2) the impact of securities and loan derecognition under a sale; (3) realized gains (losses) on securitizations; and (4) the impact of consolidation, deconsolidation and other-than-temporary impairment of available-for-sale securities. Additionally, this line includes fair value losses (gains) on trading securities, debt and derivatives. Schedule of Risk in Force Mortgage Insurance Coverage, by Counterparty Schedule Of Risk In Force Mortgage Insurance Coverage, By Counterparty [Table Text Block] Tabular disclosure of risk in force mortgage mortgage insurance coverage by counterparty. Pledged Status [Axis] Pledged Status [Axis] Trading Arrangements, by Individual Trading Arrangements, by Individual [Table] Basic (in dollars per share) Earnings Per Share, Basic Essent Guaranty, Inc. Essent Guaranty, Inc [Member] Represents one of our largest mortgage insurer counterparties, Essent Guaranty, Inc. Liabilities: Liabilities, Fair Value Disclosure [Abstract] Maximum additional collateral Additional Collateral, Aggregate Fair Value Financing Receivable, Nonaccrual [Table] Financing Receivable, Nonaccrual [Table] Total deferred tax assets Deferred Tax Assets, Gross Securities purchased under agreements to resell, or similar arrangements, gross amount Security Purchased under Agreement to Resell, Subject to Master Netting Arrangement, before Offset Other comprehensive income (loss) Other Comprehensive Income (Loss), Net of Tax Schedule of Segment Reporting Schedule of Segment Reporting Information, by Segment [Table Text Block] Short-term debt of Fannie Mae, outstanding Short-Term Debt Net change in accrued interest receivable Increase (Decrease) in Accrued Interest Receivable, Net Debt Instrument, Redemption, Period [Axis] Debt Instrument, Redemption, Period [Axis] Total gains (losses) realized & unrealized Fair Value, Asset, Recurring Basis, Still Held, Unrealized Gain (Loss) Unpaid principal balance of mortgage loans Mortgage Loans on Real Estate, Unpaid Principal Balance Represents principal amount outstanding of mortgage loans. Treasury & Freddie Mac US Treasury and Freddie Mac [Member] US Treasury and Freddie Mac Write-offs Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Writeoff Agency US Government Corporations and Agencies Securities [Member] Portfolio securitizations: unpaid principal balance Unpaid Principal Balance of Portfolio Securitizations We are considered to be the transferor when we transfer assets from our portfolio in a portfolio securitization transaction and the following represents the unpaid principal balance of portfolio securitizations which occurred during the period. Award Timing MNPI Disclosure Award Timing MNPI Disclosure [Text Block] Securities purchased under agreements to resell or similar arrangements, net amount Security Purchased under Agreement to Resell, Including Not Subject to Master Netting Arrangement, after Offset and Deduction Consolidated Trusts Variable Interest Entity, Primary Beneficiary [Member] Awarded damages Litigation Settlement, Amount Awarded from Other Party Trading securities Debt Securities, Trading, and Equity Securities, FV-NI Allowance for loan losses and total recorded investment in HFI loans [Table] Accounts and Financing Receivables [Table] Contributions for equity investments Payments to Acquire Equity Method Investments Derivative Instruments, Gain (Loss) [Line Items] Derivative Instruments, Gain (Loss) [Line Items] Asset Manager Estimate Asset Manager Estimate [Member] Valuation technique uses the net operating income and tax assessments of the specific acquired property, other asset, or collateral underlying the loan as well as MSA-specific market capitalization rates and average per unit sales values to estimate property fair value. Segment Reporting, Asset Reconciling Item [Line Items] Segment Reporting, Asset Reconciling Item [Line Items] Hedging Designation [Domain] Hedging Designation [Domain] Accrued interest receivable (includes $11,129 and $10,666, respectively, related to consolidated trusts) Accrued interest receivable related to consolidated trusts Financing Receivable, Accrued Interest, after Allowance for Credit Loss Offsetting [Table] Offsetting [Table] Disclosure of information about derivative, financial assets and liabilities that are subject to offsetting, including enforceable master netting arrangements. Total liabilities and equity Liabilities and Equity Total Capital Requirement Ratio (including Buffers) Banking Regulation, Core Leverage Capital Ratio, Actual Banking Regulation, Core Leverage Capital Ratio, Actual Concentration Risk Benchmark [Axis] Concentration Risk Benchmark [Axis] Derivative Instruments, Gain (Loss) by Hedging Relationship, by Income Statement Location, by Derivative Instrument Risk [Table] Derivative Instruments, Gain (Loss) [Table] Northeast Northeast United States [Member] Northeast includes CT, DE, ME, MA, NH, NJ, NY, PA, PR, RI, VT, VI Other, net Deferred Tax Assets, Other Mortgage and mortgage-related assets Mortgage And Mortgage Related Assets Including Acquired Credit Impaired Loans Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences derived from fair value adjustments, cost basis adjustments and impairments of loans and securities. Derivative assets, under master netting arrangements, amounts not offset in our consolidated balance sheets, collateral Derivative Asset, Subject to Master Netting Arrangement, Collateral, Obligation to Return Security Not Offset Guarantees [Abstract] Guarantees [Abstract] Accounting Policies [Abstract] Accounting Policies [Abstract] Schedule of Offsetting Offsetting [Table Text Block] Tabular disclosure of derivative, other financial assets and liabilities that are subject to offsetting, including master netting arrangements. Senior Preferred Stock Senior Preferred Stock [Member] Senior Preferred Stock is senior in liquidation preference to Fannie Mae common stock and all other series of preferred stock. Concentration Risk Type [Domain] Concentration Risk Type [Domain] Total assets, under master netting arrangements, not offset in our consolidated balance sheets, collateral Derivative Asset, Security Purchased under Agreement to Resell, and Security Borrowed, Subject to Master Netting Arrangement, Collateral, Obligation to Return Security Not Offset Treasury Stock Treasury Stock, Common [Member] Series L Series L Preferred Stock [Member] Outstanding Series L Preferred Stock. This stock has no par value, is non-participating, is non-voting and has a liquidation preference equal to the stated value per share. Pay vs Performance Disclosure [Line Items] Forward contracts to purchase mortgage-related securities Forward Contracts to Purchase Mortgage-related Securities [Member] Represents forward contract/commitment to purchase mortgage-related securities. Seriously Delinquent Financial Asset, Equal to or Greater than 90 Days Past Due [Member] Liabilities: Liabilities [Abstract] Non-mortgage-related securities Non-mortgage-related securities [Member] Represents non-mortgage-related securities in our trading securities, which includes our U.S. Treasury securities and other securities that currently contains domestic corporate debt securities. SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Abstract] SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Abstract] Total financial liabilities Financial Liabilities Fair Value Disclosure Other income (expense), net Other Noninterest Income (Expense) Other Noninterest Income (Expense) Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] Debt Instrument, Redemption, Period [Domain] Debt Instrument, Redemption, Period [Domain] Net impact of hedged mortgage assets and debt Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge Regulatory Capital Requirements Regulatory Capital Requirements under Banking Regulations [Text Block] Serious delinquency: days past due Serious Delinquency Days past due 1 Represents the number of days past due required for a loan to be considered seriously delinquent. Variable Interest Entity [Table] Variable Interest Entity [Table] Condensed Consolidated Statements of Cash Flows Statement of Cash Flows [Abstract] Company Selected Measure Amount Company Selected Measure Amount Cash Cash Total comprehensive income Comprehensive Income (Loss), Net of Tax, Attributable to Parent Name Measure Name Issuances Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Issuances Financing Receivable, Nonaccrual [Line Items] Financing Receivable, Nonaccrual [Line Items] Class of Stock [Line Items] Class of Stock [Line Items] Receive-fixed swaption Receive-fixed Swaption [Member] Represents an option on interest rate received-fixed swaps in the form of contracts granting an option to one party and creating a corresponding commitment from the counterparty to enter into specified interest rate receive-fixed swaps in the future. Swaptions are traded in the over-the-counter market and not through an exchange. Futures Future [Member] Restructured loans, amortized cost Financing Receivable, Restructured Loans Not Considered TDRs, Amortized Cost Financing Receivable, Restructured Loans Not Considered TDRs, Amortized Cost Unconsolidated Fannie Mae MBS Non-consolidated FannieMae securities [Member] Maximum potential exposure of guarantees comprised of UPB of underlying mortgage loans that are both recognized and not recognized in our balance sheets. Population primarily consist of MBS, PLS and WL REMICS. Adjustment for Change in Accounting Principle Revision of Prior Period, Adjustment [Member] Long-term debt, outstanding Total long-term debt Long-Term Debt Total assets Total Assets Total assets Assets Government US Government Agency Insured Loans [Member] Allowance for loan losses and basis in acquired property, net Deferred Tax Asset, Tax Deferred Expense, Reserve and Accrual, Financing Receivable, Allowance for Credit Loss Financing Receivable, Credit Quality Indicator [Line Items] Financing Receivable, Credit Quality Indicator [Line Items] Geographical [Domain] Geographical [Domain] Income Taxes Income Tax, Policy [Policy Text Block] West West United States [Member] West includes AK, CA, GU, HI, ID, MT, NV, OR, WA and WY. Other Other Mortgage Loan [Member] Includes mortgage loans with higher-risk characteristics, such as interest-only loans and negative-amortizing loans that are neither government nor Alt-A. Total investments in securities Debt Securities Cash flows provided by (used in) operating activities: Cash Provided by (Used in) Operating Activity, Including Discontinued Operation [Abstract] Research and development Effective Income Tax Rate Reconciliation, Tax Credit, Research, Percent Concentration Risk Type [Axis] Concentration Risk Type [Axis] Proceeds from sales Proceeds from Sale, Loan and Lease, Held-for-Investment Preferred stock dividend rate, basis spread on variable rate Preferred Stock, Dividend Rate, Basis Spread on Variable Rate The percentage points added to the reference rate to compute the variable dividend rate on the annual dividend rate. Assets: Assets, Fair Value Disclosure [Abstract] Other, tax Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Plan Amendments, Tax Effect Variable Interest Entities [Line Items] Variable Interest Entity [Line Items] Derivative assets, under master netting arrangements, amounts not offset in our consolidated balance sheets, financial instruments Derivative Asset, Subject to Master Netting Arrangement, Deduction of Financial Instrument Not Offset Minimum Capital Ratio Requirement Banking Regulation, Total Risk-Based Capital Ratio, Capital Adequacy, Minimum Variable Interest Entity Consolidation, Variable Interest Entity, Policy [Policy Text Block] Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Significant Other Observable Inputs (Level 2) Fair Value, Inputs, Level 2 [Member] Document Financial Statement Error Correction [Flag] Document Financial Statement Error Correction [Flag] Insider Trading Policies and Procedures Not Adopted Insider Trading Policies and Procedures Not Adopted [Text Block] Mortgage Guaranty Insurance Corp. Mortgage Guaranty Insurance Corp. [Member] Represents one of our largest mortgage insurer counterparties, Mortgage Guaranty Insurance Corp. Forbearance Plan Forbearance Plan [Member] Short-term Loss Mitigation Options Related Party Related Party [Member] Collateral Repurchase Agreements, Collateral, Policy [Policy Text Block] Pledged as collateral Asset Pledged as Collateral [Member] Schedule of Components of Income Tax Expense (Benefit) Schedule of Components of Income Tax Expense (Benefit) [Table Text Block] Document Information [Table] Document Information [Table] PEO PEO [Member] Total Capital Requirement (including buffers) Banking Regulation, Tier 1 Leverage Capital, Actual Investment in securities, trading, at fair value Total trading securities Debt Securities, Trading Hedged asset, discontinued fair value, remaining adjustments Hedged Asset, Discontinued Fair Value Hedge, Cumulative Increase (Decrease) Financial Guarantees and Maximum Recovery [Table] Financial Guarantees and Maximum Recovery [Table] Financial Guarantees and Maximum Recovery [Table] Total Capital Requirement (including buffers) Banking Regulation, Common Equity Tier 1 Risk-Based Capital, Actual Common equity tier 1 capital Banking Regulation, Common Equity Tier 1 Risk-Based Capital [Abstract] Valuation allowance Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount Conversion rate Conversion Stock, Conversion Rate Rate of conversion to common stock associated with each share of series 2004-1 preferred stock. Accumulated Deficit Retained Earnings [Member] Percentage of book of business Percentage of Unpaid Principal Balance of Loans Represents the percentage of unpaid principal balance of loans, by category. Cash and restricted cash at beginning of period Cash and restricted cash at end of period Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Continuing Operation Income Statement [Abstract] Derivative assets Derivative assets at fair value Derivative Asset Interest Expense Interest Expense [Member] Nonrecurring Fair Value, Nonrecurring [Member] Available Capital (Deficit) Ratio Banking Regulation, Excess (Deficit) Tier One Leverage Capital Ratio, Actual Banking Regulation, Excess (Deficit) Tier One Leverage Capital Ratio, Actual Net change in accrued interest payable Increase (Decrease) in Interest Payable, Net Minimum Capital Requirement Banking Regulation, Common Equity Tier 1 Risk-Based Capital, Capital Adequacy, Minimum Fee and other income Noninterest Income, Other Product and Service [Domain] Product and Service [Domain] Benchmark notes and bonds Senior Fixed Benchmark Notes and Bonds [Member] Senior fixed benchmark bonds represent noncallable fixed rate debt instruments with original contractual maturities greater than ten years. Senior fixed benchmark notes are regularly issued non-callable fixed rate debt instruments with original maturities from two to ten years. Senior fixed rate debt takes priority over other debt instruments sold by the company. In the event the company goes bankrupt, senior fixed rate debt holders receive priority for repayment prior to junior or unsecured general creditors. Contractual terms of our guarantees Guarantor Obligation, Term Net income Net income Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Restatement does not require Recovery Restatement Does Not Require Recovery [Text Block] Total financial liabilities Liabilities, Fair Value Disclosure Notional amount Derivative, Notional Amount Organization, Consolidation and Presentation of Financial Statements [Abstract] Series H Series H Preferred Stock [Member] Top five depository servicers Top 5 Depository Servicers [Member] Represents a servicer who is a depository institution. Securities received as collateral Securities Received as Collateral Title of 12(g) Security Title of 12(g) Security City Area Code City Area Code Allowance for Loan Losses Roll Forward by Segment Financing Receivable, Allowance for Credit Loss [Table Text Block] Award Timing, How MNPI Considered Award Timing, How MNPI Considered [Text Block] Mortgage Loans Mortgages [Member] Settlements Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Settlements Basis Basis Swap [Member] Schedule of Trading Securities and Other Trading Assets [Table] Debt Securities, Trading, and Equity Securities, FV-NI [Table] Administrative expense General and Administrative Expense Cash flows provided by (used in) investing activities: Cash Provided by (Used in) Investing Activity, Including Discontinued Operation [Abstract] Depository Servicer Depository Servicer [Member] Represents a servicer who is a depository institution. Total assets, gross amount Derivative Asset, Security Purchased under Agreement to Resell, and Security Borrowed, Subject to Master Netting Arrangement, before Offset Pay vs Performance Disclosure Pay vs Performance Disclosure [Table] Derivative Asset Statement Of Financial Position Extensible Enumeration Not Disclosed Flag Derivative Asset Statement Of Financial Position Extensible Enumeration Not Disclosed Flag Derivative Asset Statement Of Financial Position Extensible Enumeration Not Disclosed Flag Retained interests: unpaid principal balance Unpaid Principal Balance Securities Retained Unconsolidated Portfolio Securitization Trusts Represents the unpaid principal balance of securities retained in unconsolidated portfolio securitization trusts as of the period end. Series T Series T Preferred Stock [Member] Outstanding Series T Preferred Stock. This stock has no par value, is non-participating, is non-voting and has a liquidation preference equal to the stated value per share. Percentage of common shares attributable to warrants Percentage Of Common Shares Attributable to Warrants Issued to Treasury as Percentage to Total Diluted Common Shares Represents a percentage of common shares warrants issued to U.S. Treasury as a percentage of the total number of the company's diluted common shares. Primary mortgage insurance coverage risk in force Primary Mortgage Insurance Coverage Risk in Force Represents our maximum potential loss recovery under the applicable primary mortgage insurance policies. Hedged Liability Statement Of Financial Position Extensible Enumeration Not Disclosed Flag Hedged Liability Statement Of Financial Position Extensible Enumeration Not Disclosed Flag Hedged Liability Statement Of Financial Position Extensible Enumeration Not Disclosed Flag Other gains (losses), net Other Noninterest Gains (Losses), Net Other Noninterest Gains (Losses), Net Other liabilities (includes $1,719 and $1,699, respectively, related to consolidated trusts) Other liabilities Other Liabilities Investment gains (losses), net Gain (Loss) on Investments Auditor Name Auditor Name Series M Series M Preferred Stock [Member] Outstanding Series M Preferred Stock. This stock has no par value, is non-participating, is non-voting and has a liquidation preference equal to the stated value per share. Concentration Risk [Table] Concentration Risk [Table] Guaranty assets Guaranty Assets Other Performance Measure, Amount Other Performance Measure, Amount Investments in Securities Marketable Securities, Policy [Policy Text Block] Fair Value Measurements Fair Value Measurement, Policy [Policy Text Block] Related Party [Domain] Related and Nonrelated Parties [Domain] Effective Income Tax Rate Reconciliation, Amount Income Tax Expense (Benefit), Effective Income Tax Rate Reconciliation, Amount [Abstract] Credit Concentration Risk Credit Concentration Risk [Member] Net increase (decrease) in cash and restricted cash Net increase (decrease) in cash and restricted cash Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Period Increase (Decrease), Excluding Exchange Rate Effect, Including Discontinued Operation Litigation Status [Axis] Litigation Status [Axis] Derivative Instrument [Axis] Derivative Instrument [Axis] Adjusted total assets Banking Regulation, Adjusted Assets, Actual Banking Regulation, Adjusted Assets, Actual Fair Value of Financial Instruments Fair Value of Financial Instruments, Policy [Policy Text Block] Restricted cash (includes $22,848 and $16,994, respectively, related to consolidated trusts) Restricted cash Restricted Cash Financial liabilities: Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract] Basis points of each dollar of unpaid principal balance Basis Points Of Each Dollar Of Unpaid Principal Balance Represents the number of basis points for each dollar of the unpaid principal balance of its total new business purchases that Fannie Mae must set aside to fund the Housing Trust Fund and Capital Magnet Fund as required by the Federal Housing Finance Regulatory Reform Act of 2008, which was enacted on July 30, 2008. National Mortgage Insurance Corp. National Mortgage Insurance Corporation [Member] National Mortgage Insurance Corporation Mr. Cooper and Rocket Mortgage, LLC Mr. Cooper and Rocket Mortgage, LLC [Member] Mr. Cooper and Rocket Mortgage, LLC Net cash provided by (used in) investing activities Net cash provided by (used in) investing activities Cash Provided by (Used in) Investing Activity, Including Discontinued Operation Aggregate Change in Present Value of Accumulated Benefit for All Pension Plans Reported in Summary Compensation Table Aggregate Change in Present Value of Accumulated Benefit for All Pension Plans Reported in Summary Compensation Table [Member] Interest Interest Paid, Excluding Capitalized Interest, Operating Activity Document Fiscal Year Focus Document Fiscal Year Focus Basis of Presentation Basis of Accounting, Policy [Policy Text Block] Provision for U.S. federal income taxes and effective tax rate Effective Income Tax Rate Reconciliation, Percent Carrying value Reported Value Measurement [Member] Mortgage loans held for investment, net of allowance for loan losses Loans Receivable Including Mortgage Commitments, Fair Value Disclosure Loans Receivable Including Mortgage Commitments, Fair Value Disclosure Valuation allowance Deferred Tax Assets, Valuation Allowance Equity: Equity [Abstract] Net transfers Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Transfers, Net Securities purchased under agreements to resell Interest Income, Securities Purchased under Agreements to Resell Amortized cost, nonaccrual loans Financing Receivable, Nonaccrual Unconditional commitments Purchase Obligation 90.01% to 100% Original Loan to Value Ratio, 90.01% to 100% [Member] Original Loan to Value Ratio, 90.01% to 100% Derivative Instruments Derivatives, Policy [Policy Text Block] Segment Reporting Segment Reporting Disclosure [Text Block] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Risk management derivatives not designated as hedging instruments: Not Designated as Hedging Instrument [Member] Debt Debt and Lease Obligation Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] U.S. FinTech & Freddie Mac Common Securitization Solutions and Freddie Mac [Member] Common Securitization Solutions and Freddie Mac Doubtful Doubtful [Member] Compensation Actually Paid vs. Total Shareholder Return Compensation Actually Paid vs. Total Shareholder Return [Text Block] Fair Value Measurements, Recurring [Table] Fair Value, Recurring and Nonrecurring [Table] Adjustable-rate Adjustable Rate Residential Mortgage [Member] Loans Loans Receivable [Member] Total mortgage loans held for sale, at lower of cost or fair value Mortgage loans held for sale Loan, Mortgage, Held-for-Sale, Fair Value Disclosure Loans, unpaid principal balance Principal Amount Outstanding Of Loans Held For Investment Represents principal amount outstanding of loans held for investment. Assuming Callable Debt Redeemed at Next Available Call Date Earlier of Contractual Maturity or Next Call Date [Member] Long-term debt shown as the earlier of maturity date or next call date. Deferred tax assets, net Deferred Income Tax Assets, Net Minimum Capital Ratio Requirement Banking Regulation, Adjusted Total Risk-Based Capital Ratio, Capital Adequacy, Minimum Banking Regulation, Adjusted Total Risk-Based Capital Ratio, Capital Adequacy, Minimum Greater than 90% and less than or equal to 100% Estimated Mark To Market Loan To Value Ratio Greater Than 90 Percent and Less Than or Equal to 100 Percent [Member] Represents the recorded investment in loans with an estimated mark-to-market loan-to-value ratio greater than 90% and less than or equal to 100%. Conservatorship, Preferred Stock Agreements, And Related Parties Conservatorship, Preferred Stock Agreements, And Related Parties [Text Block] Conservatorship, Preferred Stock Agreements, And Related Parties Arrangement Duration Trading Arrangement Duration Investments In Trading Securities Debt Securities, Trading, and Equity Securities, FV-NI [Table Text Block] Segments [Axis] Segments [Axis] Other, net of taxes Other Comprehensive Income, Other, Net of Tax Derivative instruments Deferred Tax Assets, Derivative Instruments Medium-term notes Senior Floating Medium-term Notes [Member] Senior floating medium-term notes with interest rates that are subject to adjustment represent debt instruments with original contractual maturity dates ranging from one to ten years, excluding zero-coupon debt. Senior floating debt takes priority over other debt instruments sold by the company. In the event the company goes bankrupt, senior floating debt holders receive priority for repayment prior to junior or unsecured general creditors. Local Phone Number Local Phone Number Additional 402(v) Disclosure Additional 402(v) Disclosure [Text Block] Accrued interest receivable written off Financing Receivable, Accrued Interest, Writeoff Other, net Payment for (Proceeds from) Other Investing Activity Other, net Adjustment to Reconcile Net Income to Cash Provided by (Used in) Operating Activity, Other Item Non-Depository Servicer Non-Depository Servicer [Member] Represents a servicer who is a non-depository institution. Thereafter Long-Term Debt, Maturity, after Year Five Series F Series F Preferred Stock [Member] ASSETS Assets: Assets [Abstract] Credit enhancement derivatives Other derivatives Other Contract [Member] Underlying Security Market Price Change Underlying Security Market Price Change, Percent Fair Value Fair Value Disclosures [Text Block] Fannie Mae stockholders’ equity: Equity, Attributable to Parent [Abstract] Other Financing Receivable, Allowance for Credit Loss, Other, Including Accrued Interest Financing Receivable, Allowance for Credit Loss, Other, Including Accrued Interest Related Parties Related Parties [Policy Text Block] Related Parties Fair value of nonaccrual loans Fair Value, Option, Loans Held as Assets, Aggregate Amount in Nonaccrual Status 30-59 Days Delinquent Financial Asset, 30 to 59 Days Past Due [Member] Entity Voluntary Filers Entity Voluntary Filers Condensed Consolidated Balance Sheets Balance Sheet Related Disclosures [Abstract] TCCA fees Single-Family Guaranty Fee, Temporary Payroll Tax Cut Continuation Act of 2011 [Member] Single-Family Guaranty Fee, Temporary Payroll Tax Cut Continuation Act of 2011 Derivative liability, not subject to master netting arrangement Derivative Liability, Not Subject to Master Netting Arrangement Derivative assets, gross amount Derivative Asset, Subject to Master Netting Arrangement, before Offset Net gains related to the disposition of acquired property and preforeclosure sales, including credit enhancements Net Gains Related To The Disposition of Acquired Property and Preforeclosure Sales, Including Credit Enhancements Represents Net Gains Related To The Disposition of Acquired Property and Preforeclosure Sales, Including Credit Enhancements which are reconciling items to operating income which are included in the proceeds from dispositions of acquired property and preforeclosure sales within the investing section. Amortization of cost basis adjustments Depreciation, Amortization and Accretion, Net Entity Registrant Name Entity Registrant Name Stock Price or TSR Estimation Method Stock Price or TSR Estimation Method [Text Block] Closed portfolio, amortized cost Financial Asset, Closed Portfolio and Beneficial Interest, Portfolio Layer Method, Amortized Cost Conservatorship Conservatorship, Policy [Policy Text Block] Conservatorship, Policy Total assets at fair value Total nonrecurring assets at fair value Assets, Fair Value Disclosure (Provision) benefit for credit losses Provision (benefit) for credit losses Provision for Loan, Lease, and Other Losses Top five depository servicers Other Top Servicers [Member] Represents remaining top servicers not presented separately in the table. Revision of Prior Period [Domain] Revision of Prior Period [Domain] Total Delinquent Financial Asset, Past Due [Member] DSCR ratio Current Debt Service Coverage Ratio, Higher Risk Loans1 A multifamily loan with the current debt service ratio ('DSCR') below 1.0 is considered one of the higher risk characteristics by our management. Acquired property, net: Real Estate Acquired through Foreclosure, Fair Value Disclosure Carrying amount as of the balance sheet date of real estate owned and foreclosed assets. Foreclosed assets include all assets obtained in full or partial satisfaction of a debt arrangement through foreclosure proceedings. Related Party [Axis] Related and Nonrelated Parties [Axis] Beginning balance Ending balance Total Financing Receivable, Allowance for Credit Loss and Other, Including Accrued Interest Financing Receivable, Allowance for Credit Loss and Other, Including Accrued Interest Tax credits, percent Effective Income Tax Rate Reconciliation, Tax Credit, Percent [Abstract] Fair value of loans that are 90 days past due Fair Value, Option, Loans Held as Assets, 90 Days or More Past Due Restatement Determination Date: Restatement Determination Date [Axis] Accounts Receivable Accounts Receivable [Member] Loans Held for Investment Financing Receivable, Held-for-Investment [Policy Text Block] Financing Receivable, Loss Mitigation Financing Receivable, Loss Mitigation [Policy Text Block] Loss Mitigation Other, net Proceeds from (Payment for) Other Financing Activity Name Trading Arrangement, Individual Name Total assets, net amount presented in the consolidated balance sheets Derivative Asset, Security Purchased under Agreement to Resell, and Security Borrowed, Subject to Master Netting Arrangement, after Offset Underlying Asset Class [Domain] Underlying Asset Class [Domain] As Previously Reported Previously Reported [Member] Schedule of Short-Term Borrowings [Table] Short-Term Debt [Table] Prior Financing Receivable, Originated, More than Five Years before Current Fiscal Year, Writeoff Receivable from claims on insured, defaulted loans excluding government insured loans Receivable from Claims on defaulted loans from Mortgage Insurers Sellers and Servicers Amount due in settlement of a claim for reimbursement from an insurance company (insurers) and sellers/servicers when the Company has suffered a loss covered under the terms of an insurance policy or a seller/servicer contract. Face amount Debt Instrument, Face Amount Components of allowance for credit losses Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss [Abstract] Preferred Stock Preferred Stock [Member] Name Awards Close in Time to MNPI Disclosures, Individual Name Early lender funding advances, maximum term Early Lender Funding Advances, Maximum Term Represent the maximum number of days the lenders have when we provide early funding to lenders for loans that they will subsequently either sell to us or securitize into a Fannie Mae MBS that they will deliver to us. Advances to Lenders Advances to Lenders [Policy Text Block] Disclosure of accounting policy for cash payments made in exchange for the receipt of mortgage loans from lenders in a transfer that is accounted for as a secured lending arrangement. These transfers primarily occur when we provide early funding to lenders for loans that they will subsequently either sell to us or securitize into a Fannie Mae MBS that they will deliver to us. We individually negotiate early lender funding advances with our lender customers. Early lender funding advances have terms up to 60 days and earn a short-term market rate of interest. Cash paid during the period for: Payments for Operating Activities [Abstract] Aggregate Erroneous Compensation Not Yet Determined Aggregate Erroneous Compensation Not Yet Determined [Text Block] Broker Price Opinion Broker Price Opinion [Member] Broker Price Opinion ICFR Auditor Attestation Flag ICFR Auditor Attestation Flag Treasury stock, at cost, $150,675,136 shares Treasury Stock, Value Changes in net unrealized losses on available-for-sale securities, tax OCI, Debt Securities, Available-for-Sale, Unrealized Holding Gain (Loss), before Adjustment, Tax Transfers of Financial Assets [Line Items] Assumption for Fair Value as of Balance Sheet Date of Assets or Liabilities that relate to Transferor's Continuing Involvement [Line Items] Litigation Case [Axis] Litigation Case [Axis] Auditor Firm ID Auditor Firm ID Segment [Domain] Total Results [Domain] Segments [Domain] Statement of Income Location, Balance [Axis] Statement of Income Location, Balance [Axis] Investments in Securities Investments in Debt and Marketable Equity Securities (and Certain Trading Assets) Disclosure [Text Block] Fair Value, Measurements, Fair Value Hierarchy [Domain] Fair Value Hierarchy and NAV [Domain] Mortgage loans: Mortgage Loans on Real Estate, Commercial and Consumer, Net, (Investment Based Operations Presentation) [Abstract] FHFA Federal Housing Finance Agency [Member] Conservator to Government sponsored agencies. Estimated benefit included in combined loss reserves Insurance Loss Reserves, Contractual Mortgage Insurance Benefit, Net Estimated benefit included in total loss reserves is the contractual mortgage insurance benefits under mortgage insurance policies net of the adjustment for collectability for our mortgage insurer counterparties' inability to fully pay the contractual mortgage insurance claims. Asset Derivatives Derivative Asset [Abstract] Interest expense: Interest Expense, Operating and Nonoperating [Abstract] Earnings per Share Earnings Per Share, Policy [Policy Text Block] Netting adjustment Derivative liabilities, gross amount offset Derivative liabilities, gross amount offset Netting Adjustment Derivative Liability, Subject to Master Netting Arrangement, Asset Offset Preferred stock, $700,000,000 shares are authorized—$555,374,922 shares issued and outstanding Preferred stock Preferred Stock, Value, Issued Accrued interest payable (includes $11,320 and $10,858, respectively, related to consolidated trusts) Accrued interest payable related to consolidated trusts Interest Payable Financial Asset, Period Past Due [Axis] Financial Asset, Aging [Axis] All Executive Categories All Executive Categories [Member] Schedule of Deferred Tax Assets and Liabilities Schedule of Deferred Tax Assets and Liabilities [Table Text Block] Common stock, no par value, no maximum authorization—$1,308,762,703 shares issued and $1,158,087,567 shares outstanding Common Stock, Value, Issued Mortgage loans Interest and Fee Income, Loans and Leases Derivatives designated as hedging instruments Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments Summary of Gains (Losses) on Investments Realized Gain (Loss) on Investments [Table Text Block] Commitments and contingencies (Note 17) Commitments and Contingencies Liquidation preference Preferred Stock, Liquidation Preference, Value Total comprehensive income Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest Cleared risk management derivatives Exchange Cleared [Member] Financing Receivable, Loan Modification Financing Receivable, Loan Modification [Table Text Block] Financing Receivable, Loan Modification Interest Income Interest Income [Member] Greater than 80% Original Loan to Value Ratio Greater than Eighty Percent [Member] Represents loans with an original loan-to-value ratio greater than 80%. Midwest Midwest United States [Member] Midwest includes IL, IN, IA, MI, MN, NE, ND, OH, SD, WI. Mortgage loans in process of foreclosure Mortgage Loans in Process of Foreclosure, Amount Short-Term Debt [Line Items] Short-Term Debt [Line Items] Concentration Risk [Line Items] Concentration Risk [Line Items] Total writeoffs Financing Receivable, Revolving, Writeoff Deferred tax assets, net Deferred Tax Assets, Net 60 days delinquent (percentage of book of business) Loans 60 to 89 Days Past Due, Percentage of Unpaid Principal Balance Represents the percentage of unpaid principal balance comprised of loans 60 to 89 days past due. Calculated based on the aggregate unpaid principal balance for the category indicated, divided by the respective book of business. Hedged liability, total basis adjustments Hedged Liability, Fair Value Hedge, Cumulative Increase (Decrease) PEO Actually Paid Compensation Amount PEO Actually Paid Compensation Amount Hedged liability, carrying amount Hedged Liability, Fair Value Hedge Series N Series N Preferred Stock [Member] Outstanding Series N Preferred Stock. This stock has no par value, is non-participating, is non-voting and has a liquidation preference equal to the stated value per share. Average amount capitalized as a result of a payment delay Financing Receivable, Restructured Loans Not Considered TDRs, Average Capitalized Amount Financing Receivable, Restructured Loans Not Considered TDRs, Average Capitalized Amount 60 - 89 Days Delinquent Financial Asset, 60 to 89 Days Past Due [Member] Hedging Designation [Axis] Hedging Designation [Axis] Scenario [Axis] Scenario [Axis] Mortgage insurance coverage risk in force as a percentage of book of business Total Mortgage Insurance Coverage Risk in Force as Percentage of Unpaid Principal Balance in Guaranty Book of Business Represents mortgage insurance coverage risk in force as a percentage of unpaid principal balance. Derivative liabilities, net amount Derivative Liability, Including Not Subject to Master Netting Arrangement, after Offset and Deduction California CALIFORNIA Derivative Contract [Domain] Derivative Contract [Domain] Proceeds from issuance of common stock Proceeds from Issuance of Common Stock Allowance Rollforward [Table] Financing Receivable, Allowance for Credit Loss [Table] Available Capital (Deficit) Ratio Banking Regulation, Adjusted Total Risk-Based Capital Ratio, Excess (Deficit), Actual Banking Regulation, Adjusted Total Risk-Based Capital Ratio, Excess (Deficit), Actual Series R Series R Preferred Stock [Member] Outstanding Series R Preferred Stock. This stock has no par value, is non-participating, is non-voting and has a liquidation preference equal to the stated value per share. Net transfers Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers, Net Minimum Capital Ratio Requirement Banking Regulation, Core Leverage Capital Ratio, Capital Adequacy, Minimum Banking Regulation, Core Leverage Capital Ratio, Capital Adequacy, Minimum All Individuals All Individuals [Member] Long-term Debt, Type [Domain] Long-Term Debt, Type [Domain] Fair Value Disclosures [Abstract] Fair Value Disclosures [Abstract] Name Forgone Recovery, Individual Name Year-over-Year Change in Fair Value of Equity Awards Granted in Prior Years That are Outstanding and Unvested Year-over-Year Change in Fair Value of Equity Awards Granted in Prior Years That are Outstanding and Unvested [Member] Acquired Property, Net Financing Receivable, Real Estate Acquired Through Foreclosure [Policy Text Block] Top five non-depository servicers Top 5 Non-Depository Servicers [Member] Represents a servicer who is a non-depository institution. Seriously delinquent (percentage of conventional loans) Number of Loans Seriously Delinquent, Percentage by Category Represents the percentage of single-family loans greater than or equal to 90 days past due or multifamily loans greater than or equal to 60 days past due, included in each category. Calculated based on the number of loans in the delinquency bucket indicated, divided by the total number of loans in the respective category. Nonaccrual Loans with No Allowance(2) Financing Receivable, Nonaccrual, No Allowance LIHTC investments Effective Income Tax Rate Reconciliation, Tax Credit, Investment, Percent Error Corrections and Prior Period Adjustments Restatement [Line Items] Error Corrections and Prior Period Adjustments Restatement [Line Items] Prior Financing Receivable, Originated, More than Five Years before Current Fiscal Year Schedule of Notional and Fair Value Position Schedule of Derivative Instruments [Table Text Block] Other guaranty arrangements Guarantee Type, Other [Member] Erroneous Compensation Analysis Erroneous Compensation Analysis [Text Block] Weighted-Average Term Extension (in Months) Financing Receivable, Restructured Loans Not Considered TDRs, Weighted-Average Term Extension Financing Receivable, Restructured Loans Not Considered TDRs, Weighted-Average Term Extension Mortgage loans acquired held for investment: Proceeds From (Payments For) Loans, Held-For-Investment [Abstract] Proceeds From (Payments For) Loans, Held-For-Investment Geographical [Axis] Geographical [Axis] Senior Preferred Stock Purchase Agreements Litigation Senior Preferred Stock Purchase Agreements Litigation [Member] Senior Preferred Stock Purchase Agreements Litigation Schedule of Effect of Fair Value Hedge Accounting Schedule of Fair Value Hedging Instruments, Statements of Financial Performance and Financial Position, Location [Table Text Block] Transaction Type [Axis] Transaction Type [Axis] Liability Derivatives Derivative Liability [Abstract] Conservatorship, Preferred Stock Agreements, And Related Parties [Abstract] Conservatorship, Preferred Stock Agreements, And Related Parties Rule 10b5-1 Arrangement Terminated Rule 10b5-1 Arrangement Terminated [Flag] Hedged Asset Statement Of Financial Position Extensible Enumeration Not Disclosed Flag Hedged Asset Statement Of Financial Position Extensible Enumeration Not Disclosed Flag Hedged Asset Statement Of Financial Position Extensible Enumeration Not Disclosed Flag 20- and 30-year or more, amortizing fixed-rate Fixed Rate Residential Mortgage [Member] Forbearance and Repayment Plans and Trial Modification Forbearance and Repayment Plans and Trial Modification [Member] Forbearance and Repayment Plans and Trial Modification Current-year write-offs Unlikely to be Collected Financing Receivable [Member] Forecast Forecast [Member] Erroneously Awarded Compensation Recovery Erroneously Awarded Compensation Recovery [Table] Concentration Risk Benchmark [Domain] Concentration Risk Benchmark [Domain] (Provision) benefit for credit losses Financing Receivable, Excluding Accrued Interest, Credit Loss Expense (Reversal) Long-Term Debt by Year of Maturity [Abstract] Long-Term Debt, Fiscal Year Maturity [Abstract] Earnings per share: Earnings Per Share [Abstract] Litigation interest rate Litigation Settlement Interest Rate Litigation Settlement Interest Rate Minimum Capital Requirement Banking Regulation, Core Leverage Capital, Capital Adequacy, Minimum Banking Regulation, Core Leverage Capital, Capital Adequacy, Minimum Mortgage loans acquired by assuming debt Noncash or Part Noncash Acquisition, Debt Assumed Enact Mortgage Insurance Corp. Genworth Mortgage Insurance Corp. [Member] Represents one of our largest mortgage insurer counterparties, Genworth Mortgage Insurance Corp. Gains (losses) recognized in net interest income on fair value hedging relationships Gain (Loss) on Fair Value Hedges Recognized in Earnings Maximum recovery Maximum Recovery Represents the maximum amount we could recover through available credit enhancements and recourse with third parties on guarantees recognized in our on and off balance sheets. 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. Value assigned to Treasury's commitment and recorded as a reduction to additional paid-in-capital Adjustments to Additional Paid in Capital, Other Percentage of Then-current liquidation preference of senior preferred stock Dividends Due To Treasury, Annual Rate On Then-Current Liquidation Preference Of The Senior Preferred Stock Dividends Due To Treasury, Annual Rate On Then-Current Liquidation Preference Of The Senior Preferred Stock Dividends distributed or amounts attributable to senior preferred stock Preferred Stock Dividends and Other Adjustments Allowance for Loan Losses [Line Items] Financing Receivable, Allowance for Credit Loss [Line Items] Greater than 80% and less than or equal to 90% Estimated Mark To Market Loan To Value Ratio Greater Than 80 Percent and Less Than or Equal to 90 Percent [Member] Represents the recorded investment in loans with an estimated mark-to-market loan-to-value ratio greater than 80% and less than or equal to 90%. Schedule of Trading Securities Gains (Losses), Net Schedule of Trading Securities Gains (Losses), Net [Table Text Block] Represents a tabular disclosure of net trading gains and losses that have been recognized in earnings (statement of operations and comprehensive income) and net trading gains and losses recorded in the period related to securities held at period end. Award Timing Disclosures [Line Items] Measurement Frequency [Domain] Measurement Frequency [Domain] Risk-based capital: Banking Regulation, Risk-based Capital [Abstract] Banking Regulation, Risk-based Capital Senior preferred stock (liquidation preference of $226,984 and $212,029, respectively) Senior preferred stock value Senior Preferred Stock Value Aggregate stated value of senior preferred stock issued and outstanding Equity Equity [Text Block] Four fiscal years, writeoff Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year, Writeoff Loan Restructuring Modification [Domain] Loan Restructuring Modification [Domain] Total loans held for investment, net of allowance Financing Receivable, Excluding Accrued Interest, after Allowance for Credit Loss Two fiscal years before Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year Illinois ILLINOIS Qualitative and Quantitative Information, Transferor's Continuing Involvement, Transferred Financial Assets, by Transfer or Transferee [Axis] Qualitative and Quantitative Information, Transferor's Continuing Involvement, Transferred Financial Assets, by Transfer or Transferee [Axis] Net income Net income Net Income (Loss) Attributable to Parent Total Capital Requirement Ratio (including Buffers) Banking Regulation, Total Risk-Based Capital Ratio, Actual Single-family loans sold, realized gain, net Gain (Loss) on Sale of Mortgage Loans Schedule of Effective Income Tax Rate Reconciliation Schedule of Effective Income Tax Rate Reconciliation [Table Text Block] Other Effective Income Tax Rate Reconciliation, Other Adjustments, Percent Maximum potential loss recovery from lenders under risk sharing agreements Loss Contingency, Related Receivable, Maximum Represent maximum loss recovery from lenders under risk share agreements. Segment Reporting Information [Line Items] Segment Reporting Information [Line Items] Preferred stock, shares authorized (in shares) Preferred Stock, Shares Authorized Adoption Date Trading Arrangement Adoption Date All other states Other States [Member] Represents all other states not presented separately in the table. Receive-fixed Receive-fixed Swap [Member] Represents an agreement under which we make a variable interest payment based upon a stated index, with the index resetting at regular intervals, and receive a predetermined fixed rate of interest based upon a set notional amount and over a specified period of time. These contracts generally increase in value as interest rates fall and decrease in value interest rates rise. Financing Receivable, Past Due [Table] Financing Receivable, Past Due [Table] Current DSCR below 1.0 Current Debt Service Coverage Ratio Less than One Hundred Percent [Member] Represents loans with a current debt service coverage ratio of less than 1.0. Florida FLORIDA Available Capital (Deficit) Banking Regulation, Tier One Risk-Based Capital, Excess (Deficit), Actual Banking Regulation, Tier One Risk-Based Capital, Excess (Deficit), Actual Accumulated deficit Retained Earnings (Accumulated Deficit) Cost basis and fair value adjustments, net Mortgage Loans, Cost Basis and Fair Value Adjustments, Net Represents premiums over or discounts from face amounts of loans that are being amortized into income as an adjustment to yield and fair value adjustments. Year-end Fair Value of Equity Awards Granted in Covered Year that are Outstanding and Unvested Year-end Fair Value of Equity Awards Granted in Covered Year that are Outstanding and Unvested [Member] Class of Stock [Axis] Class of Stock [Axis] Total liabilities, gross amount Derivative Liability, Security Sold under Agreement to Repurchase, and Security Loaned, Subject to Master Netting Arrangement, before Offset Aggregate Grant Date Fair Value of Equity Award Amounts Reported in Summary Compensation Table Aggregate Grant Date Fair Value of Equity Award Amounts Reported in Summary Compensation Table [Member] Statement [Table] Statement [Table] Deferred income tax provision (provision) Deferred Income Tax Expense (Benefit) Reconciliation of net income to net cash provided by (used in) operating activities: Adjustment to Reconcile Net Income to Cash Provided by (Used in) Operating Activity [Abstract] Cash flows provided by (used in) financing activities: Cash Provided by (Used in) Financing Activity, Including Discontinued Operation [Abstract] Senior preferred stock issued (in shares) Shares, Issued Total Capital Requirement (including buffers) Banking Regulation, Core Leverage Capital, Actual Banking Regulation, Core Leverage Capital, Actual Variable Rate [Domain] Variable Rate [Domain] Senior preferred stock, stated value per share (in dollars per share) Senior Preferred Stock, Liquidation Preference Per Share Senior Preferred Stock, Liquidation Preference Per Share Net change in trading securities Increase (Decrease) in Debt Securities, Trading, and Equity Securities, FV-NI Derivative Gain Loss Statement Of Income Or Comprehensive Income Extensible Enumeration Not Disclosed Flag Derivative Gain Loss Statement Of Income Or Comprehensive Income Extensible Enumeration Not Disclosed Flag Derivative Gain Loss Statement Of Income Or Comprehensive Income Extensible Enumeration Not Disclosed Flag All Adjustments to Compensation All Adjustments to Compensation [Member] Derivative liabilities, net amount presented in our consolidated balance sheets Derivative Liability, Subject to Master Netting Arrangement, before Offset of Collateral Amendment Flag Amendment Flag Sales Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Sales Total assets, net amount Derivative Asset, Security Purchased under Agreement to Resell, and Security Borrowed, Including Not Subject to Master Netting Arrangement, after Offset and Deduction Termination Date Trading Arrangement Termination Date Amortized cost Financing Receivable, Reclassification to Held-for-Sale Freddie Mac collateral included in Fannie Mae commingled security Freddie Mac Collateral Included In Fannie Mae Commingled Security Portion of Freddie Mac securities backing commingled Fannie Mae-issued structured securities. Insider Trading Policies and Procedures Adopted Insider Trading Policies and Procedures Adopted [Flag] Service Providers [Domain] Service Providers [Domain] Represents service providers. Discontinued hedge-related basis adjustment amortization Discontinued hedge related basis adjustment amortization Discontinued hedge related basis adjustment amortization Allowance for loan losses Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest Pay-fixed swaption Pay-fixed Swaption [Member] Represents an option on interest rate pay-fixed swaps in the form of contracts granting an option to one party and creating a corresponding commitment from the counterparty to enter into specified interest rate pay-fixed swaps in the future. Swaptions are traded in the over-the-counter market and not through an exchange. Total financial assets Financial Assets Fair Value Disclosure Financial Assets Fair Value Disclosure Net carrying amount Net Assets Aggregate funding received from US Treasury pursuant to the senior preferred stock purchase agreement Aggregate Funding Received From US Treasury Pursuant To the Senior Preferred Stock Purchase Agreement Represents the aggregated funding received to date from U.S. Treasury under the terms of the senior preferred stock purchase agreement. Basic (in shares) Weighted Average Number of Shares Outstanding, Basic Derivative assets, gross Derivative Asset, Gross Asset Including Not Subject to Master Netting Arrangement Related Party Transaction [Domain] Related Party Transaction [Domain] Segment Reporting [Abstract] Segment Reporting [Abstract] Debt Disclosure [Abstract] Debt Disclosure [Abstract] Increase in net worth Net Worth, Increase (Decrease) Net Worth, Increase (Decrease) 30 days delinquent (percentage of book of business) Loans 30 to 59 Days Past Due, Percentage of Unpaid Principal Balance Represents the percentage of unpaid principal balance comprised of loans 30 to 59 days past due. Calculated based on the aggregate unpaid principal balance for the category indicated, divided by the respective book of business. Scenario [Domain] Scenario [Domain] Accepted Offer and Appraisal Accepted Offer and Appraisal [Member] Accepted Offer and Appraisal Proportional amortization, net of other tax benefits, on LIHTC investments Effective Income Tax Rate Reconciliation, Proportional Amortization on Investments, Net of Other Tax Benefits, Amount Effective Income Tax Rate Reconciliation, Proportional Amortization on Investments, Net of Other Tax Benefits, Amount Proceeds from disposition of acquired property, preforeclosure sales and insurance proceeds Proceeds from Sale of Foreclosed Assets Available Capital (Deficit) Banking Regulation, Total Risk-Based Capital, Excess (Deficit), Actual Banking Regulation, Total Risk-Based Capital, Excess (Deficit), Actual Forgone Recovery due to Expense of Enforcement, Amount Forgone Recovery due to Expense of Enforcement, Amount Consolidated Entities [Axis] Consolidated Entities [Axis] Fair Value Inputs Quantitative Information [Table] Fair Value Inputs Quantitative Information [Table] Schedule of the inputs used in the fair value measurement of assets and liabilities. This disclosure may include, but is not limited to, the fair value of the asset and liability, valuation technique used to measure fair value, the inputs used to measure fair value, the ranges of the inputs, and the weighted averages of the inputs. Use of Estimates Use of Estimates, Policy [Policy Text Block] Settlements Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements Guarantor Obligations, Nature [Axis] Guarantor Obligations, Nature [Axis] Total Capital Requirement (including buffers) Banking Regulation, Total Capital, Actual Netting Adjustment Derivative asset, gross amount offset Derivative Asset, Subject to Master Netting Arrangement, Liability Offset Insider Trading Arrangements [Line Items] Current Financial Asset, Not Past Due [Member] Total liabilities Liabilities Aggregate liquidation preference of senior preferred stock Aggregate Liquidation Preference of Senior Preferred Stock Represents the aggregated liquidation preference of senior preferred stock issued and outstanding held by U.S. Treasury. Series G Series G Preferred Stock [Member] Pension Adjustments Prior Service Cost Pension Adjustments Prior Service Cost [Member] Material Terms of Trading Arrangement Material Terms of Trading Arrangement [Text Block] Offsetting Assets [Line Items] Offsetting Assets [Line Items] Available Capital (Deficit) Banking Regulation, Excess (Deficit) Core Leverage Capital, Actual Banking Regulation, Excess (Deficit) Core Leverage Capital, Actual Derivative liabilities, under master netting arrangements, amounts not offset in our consolidated balance sheets, collateral Derivative Liability, Subject to Master Netting Arrangement, Collateral, Right to Reclaim Security Not Offset Treasury US Treasury [Member] Represent the company's related transactions with the U.S. Treasury. Variable Rate [Axis] Variable Rate [Axis] Consolidation Items [Axis] Consolidation Items [Axis] Derivative Liability Statement Of Financial Position Extensible Enumeration Not Disclosed Flag Derivative Liability Statement Of Financial Position Extensible Enumeration Not Disclosed Flag Derivative Liability Statement Of Financial Position Extensible Enumeration Not Disclosed Flag Counterparty Name [Axis] Counterparty Name [Axis] Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code Non-NEOs Non-NEOs [Member] Fair value of securities received as collateral that can be resold or repledged Fair Value of Securities Received as Collateral that Can be Resold or Repledged Posted collateral Collateral Already Posted, Aggregate Fair Value UNITED STATES