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 Debt and Equity Securities, FV-NI [Line Items] 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] Original LTV ratio 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] 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 Credit risk transfer SPVs Available-for-Sale Securities Debt Securities [Member] 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] Financing Receivable Portfolio Segment [Domain] Financing Receivable Portfolio Segment [Domain] Recoveries Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Recovery Fair value gains (losses), net Fair Value, Option, Changes in Fair Value, Gain (Loss) After Ten Years Debt Securities, Available-for-Sale, Maturity, Allocated and Single Maturity Date, Rolling after 10 Years, Amortized Cost 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 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 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 Unconsolidated VIEs 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] 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. Derivatives, Offsetting Derivatives, Offsetting Fair Value Amounts, Policy [Policy Text Block] Total stockholders’ equity Equity, Attributable to Parent Measurement Frequency [Axis] Measurement Frequency [Axis] Debt Securities, Available-for-Sale [Table] Debt Securities, Available-for-Sale [Table] 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] 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 Concentrations of Credit Risk Concentration Risk, Credit Risk, Policy [Policy Text Block] LIABILITIES AND EQUITY Liabilities and Equity [Abstract] Cover page. Cover [Abstract] Portion at Fair Value Measurement [Member] Portion at Fair Value Measurement [Member] Maximum Maximum [Member] Fair Value Measurements Using Significant Unobservable Inputs (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] Net unrealized losses on AFS investments Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain (Loss), before Tax 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 (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] Proceeds from 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] Business segments Operating Segments [Member] 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 Consensus, Single Vendor, and Discounted Cash Flow Primarily Discounted Cash Flow, Single Vendor, and Consensus [Member] Primarily Discounted Cash Flow, Single Vendor, and Consensus Texas TEXAS Broker Price Opinion and Appraisal Broker Price Opinion and Appraisal [Member] Broker Price Opinion and Appraisal 15-year or less, amortizing fixed-rate 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 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] Total carrying amount Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, after Allowance for Credit Loss Award Type Award Type [Axis] Fannie Mae Parent Company [Member] 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. 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) Senior fixed 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 Income Statement Location [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 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 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] Total 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 outstanding (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 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] Guaranty 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] 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 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 Preferred stock issued (shares) Preferred Stock, Shares Issued Pension Adjustments Service Cost Pension Adjustments Service Cost [Member] Designated as Hedging Instrument Designated as Hedging Instrument [Member] 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] 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] Commitments and Contingencies Commitments and Contingencies, Policy [Policy Text Block] 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 Total Fair Value 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. Proceeds from sales of available-for-sale securities Proceeds from Sale of Debt Securities, Available-for-Sale Sales Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales Net interest income Net contractual interest income (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 Total Carrying Amount Debt Securities, Available-for-Sale, Amortized Cost, Rolling Maturity [Abstract] Restructured loans, amortized cost, 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 condensed consolidated balance sheets, financial instruments 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 included in net income, tax Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, Tax Number of reportable business segments Number of Reportable Segments Unamortized discounts and premiums, fair value adjustments, hedge-related cost basis 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, at fair value Mortgage loans held for investment, net of allowance for loan losses Loans Receivable, Fair Value Disclosure Senior floating other debt 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. Individual: Individual [Axis] 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, under master netting arrangements, amounts not offset in our condensed 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 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 Delay as a Result of a Payment Deferral (Only) Payment Deferral [Member] Transfers of Financial Assets and Portfolio Securitizations 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 Entity Central Index Key Entity Central Index Key PEO Name PEO Name 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] 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] 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] 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 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 Mortgage Loans Held-for-sale Financing Receivable, Held-for-Sale [Policy Text Block] Accumulated Other Comprehensive Income (Loss) AOCI Attributable to Parent [Member] Internal Credit Assessment [Axis] Internal Credit Assessment [Axis] Interest accruals on 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] Fair Value as of Grant Date Award Grant Date Fair Value Table Footnote [Abstract] 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] Document Quarterly Report Document Quarterly Report 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. Level 3 Assets Measured on Recurring and Nonrecurring Basis Fair Value Measurement Inputs and Valuation Techniques [Table Text Block] Long-term 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] Securities purchased under agreements to resell, under master netting arrangements, amounts not offset in our condensed 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] 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 Total 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] Allowance reversed at time of redesignation Financing Receivable, Transfer to Held-for-Sale, Allowance for Credit Loss, Expense Reversal All Award Types Award Type [Domain] Net revenues Revenues, Net of Interest Expense 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] Estimated Fair Value Estimate of Fair Value Measurement [Member] MNPI Disclosure Timed for Compensation Value MNPI Disclosure Timed for Compensation Value [Flag] Derivative assets, net amount presented in our condensed 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, Option, Quantitative Disclosures [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 condensed 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. Accumulated other comprehensive income (loss) Accumulated Other Comprehensive Income (Loss), Net of Tax Fair Value, Option, Eligible Item or Group [Domain] Financial Instruments [Domain] Financial Instruments [Domain] Purchases Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases 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 income (expense), 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 Minimum Minimum [Member] Limited partnerships, including low income housing tax credit ("LIHTC") investments 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 (loss) 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] Weighted-average common shares outstanding, Diluted (shares) Weighted Average Number of Shares Outstanding, Diluted Short-term debt, weighted-average interest rate (percent) 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 condensed 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 Preferred stock outstanding (shares) Preferred Stock, Shares Outstanding Document Transition Report Document Transition Report Senior fixed other debt 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. 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 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 Net liability position Derivative, Net Liability Position, Aggregate Fair Value Closed portfolio, designated UPB Hedged Asset, Fair Value Hedge, Portfolio Layer Method, Hedged Layer, Amount 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) 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] 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 US 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 After One Year Through Five Years Debt Securities, Available-for-Sale, Maturity, Allocated and Single Maturity Date, Rolling after One Through Five Years, Fair Value Net income (loss) 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 Assessment Expense Legislative Assessment Expense Guarantor Obligation, Nature [Domain] Guarantor Obligations, Nature [Domain] Fair Value Gain (Loss), Net Derivative Instruments, Gain (Loss) [Table Text Block] Derivatives, Methods of Accounting, Hedging Derivatives 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) Shares, Outstanding Core capital (statutory) Banking Regulation, Core Leverage Capital [Abstract] Banking Regulation, Core Leverage Capital Securities purchased under agreements to resell, net amount presented in our condensed consolidated balance sheets Securities Purchased under Agreements to Resell, Not Subject to Master Netting Arrangement Schedule of Related Party Transactions, by Related Party [Table] Related Party Transaction [Table] Earnings per share, Diluted (in usd per share) Earnings Per Share, Diluted Multifamily Multifamily [Member] Loans held for sale, at lower of cost or fair value Financing Receivable, Held-for-Sale Treasury stock at cost (shares) Treasury Stock, Common, Shares Consolidation Items [Domain] Consolidation Items [Domain] Weighted average number of contingently issuable shares (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 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] 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. Long-term debt, unpaid principal balance Long-Term Debt, Gross Changes in net unrealized gains (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. Regulatory Capital Classification Measures Schedule of Compliance with Regulatory Capital Requirements under Banking Regulations [Table Text Block] After Five Years Through Ten Years Debt Securities, Available-for-Sale, Maturity, Allocated and Single Maturity Date, Rolling after 5 through 10 Years, Fair Value Loans held for investment, at amortized cost: 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, Restructured Loans Not Considered TDRs, Percent of Total Financing Receivable 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 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 Weighted-average interest rate, One Year or Less Debt Securities, Available-for-Sale, Maturity, Rolling within One Year, Weighted Average Yield 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] 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 condensed consolidated balance sheets Derivative Liability, Security Sold under Agreement to Repurchase, and Security Loaned, Subject to Master Netting Arrangement, after Offset Eligible Item or Group for Fair Value Option [Axis] Financial Instrument [Axis] Financial Instrument [Axis] 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] 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 Derivative liabilities at fair value Derivative Liability Other noninterest expense Other Noninterest Expense Four fiscal years before Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year 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] Derivative assets not subject to enforceable master netting arrangements 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] 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] Financing Receivable, Past Due Financing Receivable, Past Due [Table Text Block] Greater than 100% 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%. 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 fair value gains (losses), net 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] After Ten Years Debt Securities, Available-for-Sale, Maturity, Allocated and Single Maturity Date, Rolling after 10 Years, Fair Value 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 Retained interests: 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. Summary of Unconsolidated Variable Interest Entities Schedule of Variable Interest Entities [Table Text Block] Net Derivatives Derivative [Member] Common stock issued (shares) Common Stock, Shares, Issued 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] Total allowance for credit losses: Allowance for Loan and Lease Losses [Roll Forward] Agency Mortgage-Backed Security, Issued by US Government-Sponsored Enterprise [Member] Trading Arrangement: Trading Arrangement [Axis] Total Shareholder Return Amount Total Shareholder Return Amount Loss Contingencies [Line Items] Loss Contingencies [Line Items] Real Estate, Type of Property [Axis] Real Estate, Type of Property [Axis] Netting Arrangements Netting Arrangements [Text Block] The entire disclosure for balance sheet offsetting/netting arrangements. Securities purchased under agreements to resell (includes $19,450 and $18,425, respectively, related to consolidated trusts) Securities purchased under agreements to resell Securities Purchased under Agreements to Resell Total risk management derivatives designated as hedging instruments 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 Securitization and resecuritization trusts 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 Total 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 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] Fair Value Inputs Quantitative Information [Table] Fair Value Measurement Inputs and Valuation Techniques [Table] Common Common Stock [Member] Issuances Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Issuances 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, 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] 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 Total interest income recognized Financing Receivable, Nonaccrual, Interest Income Long-term debt, weighted-average interest rate (percent) 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] 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% Pledged Status [Axis] Pledged Status [Axis] Trading Arrangements, by Individual Trading Arrangements, by Individual [Table] Earnings per share, Basic (in usd per share) Earnings Per Share, Basic Liabilities: Liabilities, Fair Value Disclosure [Abstract] Additional collateral Additional Collateral, Aggregate Fair Value Financing Receivable, Nonaccrual [Table] Financing Receivable, Nonaccrual [Table] Securities purchased under agreements to resell, 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, outstanding Short-Term Debt Total gains (losses) realized & unrealized Fair Value, Asset, Recurring Basis, Still Held, Unrealized Gain (Loss) Total UPB of mortgage loans Mortgage Loans on Real Estate, Unpaid Principal Balance Represents principal amount outstanding of mortgage loans. Write-offs Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Writeoff 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, net amount Security Purchased under Agreement to Resell, Including Not Subject to Master Netting Arrangement, after Offset and Deduction Consolidated Trusts Consolidated trusts Variable Interest Entity, Primary Beneficiary [Member] Awarded damages to Fannie Mae 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] Derivative Instruments, Gain (Loss) [Line Items] Derivative Instruments, Gain (Loss) [Line Items] Asset Manager Estimate Asset Manager Estimate [Member] Asset Manager Estimate Segment Reporting, Asset Reconciling Item [Line Items] Segment Reporting, Asset Reconciling Item [Line Items] Hedging Designation [Domain] Hedging Designation [Domain] Accrued interest receivable (includes $11,275 and $11,129, respectively, related to consolidated trusts) Accrued interest receivable, net 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] Derivative assets, under master netting arrangements, amounts not offset in our condensed 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] Weighted-average interest rate, After Ten Years Debt Securities, Available-for-Sale, Maturity, Rolling after 10 Years, Weighted Average Yield 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 Senior Preferred Stock [Member] Senior Preferred Stock is senior in liquidation preference to Fannie Mae common stock and all other series of preferred stock. Total assets, under master netting arrangements, amounts not offset in our condensed 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] 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) Net worth Banking Regulation, Mortgage Banking, Net Worth, Actual 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] Hedged items 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. Schedule of Variable Interest Entities [Table] Variable Interest Entity [Table] Statement of Cash Flows [Abstract] 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] Receive-fixed 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 Long-Term Debt Total assets Total Assets Total assets Assets U.S Government US Government Agency Insured Loans [Member] Financing Receivable, Credit Quality Indicator [Line Items] Financing Receivable, Credit Quality Indicator [Line Items] Geographical [Domain] Geographical [Domain] 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 Proceeds from sales Proceeds from Sale, Loan and Lease, Held-for-Investment Assets: Assets, Fair Value Disclosure [Abstract] Other, tax Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Plan Amendments, Tax Effect After One Year Through Five Years Debt Securities, Available-for-Sale, Maturity, Allocated and Single Maturity Date, Rolling after One Through Five Years, Amortized Cost Variable Interest Entities [Line Items] Variable Interest Entity [Line Items] Minimum Capital Ratio Requirement Banking Regulation, Total Risk-Based Capital Ratio, Capital Adequacy, Minimum Derivative assets, under master netting arrangements, amounts not offset in our condensed consolidated balance sheets, financial instruments Derivative Asset, Subject to Master Netting Arrangement, Deduction of Financial Instrument Not Offset Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Debt Securities, Available-for-sale [Line Items] Debt Securities, Available-for-Sale [Line Items] Significant Other Observable Inputs (Level 2) Fair Value, Inputs, Level 2 [Member] Insider Trading Policies and Procedures Not Adopted Insider Trading Policies and Procedures Not Adopted [Text Block] 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] 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 Investments Classified by Contractual Maturity Date Investments Classified by Contractual Maturity Date [Table Text Block] 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] One Year or Less Debt Securities, Available-for-Sale, Maturity, Allocated and Single Maturity Date, Rolling within One Year, Fair Value 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] 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 and restricted cash Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Continuing Operation Income Statement [Abstract] Income Statement [Abstract] Derivative assets Derivative assets at fair value Derivative Asset Interest Expense Interest Expense [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 Nonrecurring Fair Value, Nonrecurring [Member] 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] Senior fixed 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 (Loss), Including Portion Attributable to Noncontrolling Interest Restatement does not require Recovery Restatement Does Not Require Recovery [Text Block] Total liabilities at fair value Liabilities, Fair Value Disclosure Notional Amount Derivative, Notional Amount Securities received as collateral Securities Received as Collateral City Area Code City Area Code Financing Receivable, Allowance for Credit Loss 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] Debt Securities, Trading, and Equity Securities, FV-NI [Table] Schedule of Trading Securities and Other Trading Assets [Table] Debt Securities, Trading, and Equity Securities, FV-NI [Table] Administrative expenses General and Administrative Expense Cash flows provided by (used in) investing activities: Cash Provided by (Used in) Investing Activity, Including Discontinued Operation [Abstract] 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] 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. 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. Other gains (losses), net Other Noninterest Gains (Losses), Net Other Noninterest Gains (Losses), Net Other liabilities (includes $1,700 and $1,719, respectively, related to consolidated trusts) Other liabilities Other Liabilities Investment gains (losses), net Gain (Loss) on Investments Weighted-average interest rate, After Five Years Through Ten Years Debt Securities, Available-for-Sale, Maturity, Rolling after 5 through 10 Years, Weighted Average Yield 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 Measurement Fair Value Measurement, Policy [Policy Text Block] Related Party [Domain] Related and Nonrelated Parties [Domain] 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, by Nature [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 $26,323 and $22,848, respectively, related to consolidated trusts) Restricted Cash Financial liabilities: Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract] 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] 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 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 Recorded investment in nonaccrual loans Financing Receivable, Nonaccrual 90.01% to 100% Original Loan to Value Ratio, 90.01% to 100% [Member] Original Loan to Value Ratio, 90.01% to 100% 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] Not Designated as Hedging Instrument Not Designated as Hedging Instrument [Member] Debt: Debt and Lease Obligation Increase (Decrease) in Stockholders' Equity [Rollforward] Increase (Decrease) in Stockholders' Equity [Roll Forward] 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] 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. 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, Senior Preferred Stock Purchase Agreement and Related Matters 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] Business Segments [Axis] Segments [Axis] Other (net of taxes) Other Comprehensive Income, Other, Net of Tax Senior floating 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 through the reversal of interest income: Financing Receivable, Accrued Interest, Writeoff Other, net Payment for (Proceeds from) Other Investing Activity ASSETS Assets: Assets [Abstract] 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 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] Derivative liabilities not subject to enforceable master netting arrangements Derivative Liability, Not Subject to Master Netting Arrangement Derivative assets, gross amount Derivative Asset, Subject to Master Netting Arrangement, before Offset 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 Assets, Fair Value Disclosure (Provision) benefit for credit losses (Provision) benefit for credit losses Provision for Loan, Lease, and Other Losses Revision of Prior Period [Domain] Revision of Prior Period [Domain] Total Delinquent Financial Asset, Past Due [Member] Current debt service coverage ratio (higher risk loans) 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 Fair value of loans that are 90 days or more past due Fair Value, Option, Loans Held as Assets, 90 Days or More Past Due Restatement Determination Date: Restatement Determination Date [Axis] Mortgage Loans Held-for-investment Financing Receivable, Held-for-Investment [Policy Text Block] Mortgage Loans Loss Mitigation Financing Receivable, Loss Mitigation [Policy Text Block] Loss Mitigation After Five Years Through Ten Years Debt Securities, Available-for-Sale, Maturity, Allocated and Single Maturity Date, Rolling after 5 through 10 Years, Amortized Cost Other, net Proceeds from (Payment for) Other Financing Activity Name Trading Arrangement, Individual Name Total assets, net amount presented in our condensed 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] Schedule of Short-Term Debt [Table] Short-Term Debt [Table] Prior Financing Receivable, Originated, More than Five Years before Current Fiscal Year, Writeoff Weighted-average interest rate, After One Year Through Five Years Debt Securities, Available-for-Sale, Maturity, Rolling after One Through Five Years, Weighted Average Yield Components of allowance for credit losses: Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss [Abstract] Preferred Preferred Stock [Member] Name Awards Close in Time to MNPI Disclosures, Individual Name 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 Total Fair Value Debt Securities, Available-for-Sale, Maturity, Fair Value, Rolling Maturity [Abstract] Treasury stock, at cost, 150,675,136 shares Treasury Stock, Value Changes in net unrealized gains (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] Segment [Domain] Total Results [Domain] Segments [Domain] Income Statement Location [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] 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 Derivative Liability, Subject to Master Netting Arrangement, Asset Offset Purchases of available-for-sale securities Payments to Acquire Debt Securities, Available-for-Sale Preferred stock, 700,000,000 shares are authorized—555,374,922 shares issued and outstanding Preferred Stock, Value, Issued Accrued interest payable (includes $11,277 and $11,320, respectively, related to consolidated trusts) Accrued interest payable Interest Payable Financial Asset, Period Past Due [Axis] Financial Asset, Aging [Axis] All Executive Categories All Executive Categories [Member] 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 Commitments and contingencies (Note 14) Commitments and Contingencies 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] Original LTV ratio 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%. 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 writeoff Financing Receivable, Revolving, Writeoff 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 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] Derivative liabilities, net amount Derivative Liability, Including Not Subject to Master Netting Arrangement, after Offset and Deduction California CALIFORNIA Derivative Contract Type [Domain] Derivative Contract [Domain] 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 Net transfers Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers, Net Gross realized losses on AFS securities Debt Securities, Available-for-Sale, Realized Loss 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] 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 Financing Receivable, Nonaccrual, No Allowance Prior Financing Receivable, Originated, More than Five Years before Current Fiscal Year 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 Fair Value Hedging Instruments, Statements of Financial Performance and Financial Position, Location 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] 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) One Year or Less Debt Securities, Available-for-Sale, Maturity, Allocated and Single Maturity Date, Rolling within One Year, Amortized Cost 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 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. Weighted-average interest rate Debt Securities, Available-for-Sale, Weighted Average Yield Dividends distributed or amounts attributable to senior preferred stock Preferred Stock Dividends and Other Adjustments Financing Receivable, Allowance for Credit Loss [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] Risk-based capital: Banking Regulation, Risk-based Capital [Abstract] Banking Regulation, Risk-based Capital Measurement Frequency [Domain] Measurement Frequency [Domain] Senior preferred stock (liquidation preference of $230,511 and $226,984, respectively) Senior preferred stock Senior Preferred Stock Value Aggregate stated value of senior preferred stock issued and outstanding 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 Segment Reporting Information [Line Items] Segment Reporting Information [Line Items] Preferred stock authorized (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. Available Capital (Deficit) Banking Regulation, Tier One Risk-Based Capital, Excess (Deficit), Actual Banking Regulation, Tier One Risk-Based Capital, Excess (Deficit), Actual Florida FLORIDA Accumulated deficit Retained Earnings (Accumulated Deficit) Cost basis and fair value adjustments, net Mortgage Loans, Cost Basis and Fair Value Adjustments, Net Mortgage Loans, Cost Basis and Fair Value Adjustments, Net 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] Cash flows provided by (used in) financing activities: Cash Provided by (Used in) Financing Activity, Including Discontinued Operation [Abstract] Total Capital Requirement (including Buffers) Banking Regulation, Core Leverage Capital, Actual Banking Regulation, Core Leverage Capital, Actual All Adjustments to Compensation All Adjustments to Compensation [Member] Derivative liabilities, net amount presented in our condensed 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 Single security, Freddie Mac issued securities backing unconsolidated Fannie Mae securities 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] Discontinued hedge related basis adjustment amortization Discontinued hedge related basis adjustment amortization Discontinued hedge related basis adjustment amortization Allowance for loan losses Allowance for loan losses for HFI loans Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest Pay-fixed 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. Weighted-average common shares outstanding, Basic (shares) Weighted Average Number of Shares Outstanding, Basic Derivative assets, gross Derivative Asset, Gross Asset Including Not Subject to Master Netting Arrangement Segment Reporting [Abstract] Segment Reporting [Abstract] Debt Disclosure [Abstract] Debt Disclosure [Abstract] 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 Proceeds from disposition of acquired property, preforeclosure sales and insurance proceeds Proceeds from Sale of Foreclosed Assets Available Capital (Deficit) (less than in 2026) 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 Obligation, Nature [Axis] Guarantor Obligations, Nature [Axis] Total Capital Requirement (including Buffers) Banking Regulation, Total Capital, Actual Derivative assets, 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 Pension Adjustments Prior Service Cost Pension Adjustments Prior Service Cost [Member] Material Terms of Trading Arrangement Material Terms of Trading Arrangement [Text Block] Available Capital (Deficit) Banking Regulation, Excess (Deficit) Core Leverage Capital, Actual Banking Regulation, Excess (Deficit) Core Leverage Capital, Actual Offsetting Assets [Line Items] Offsetting Assets [Line Items] Derivative liabilities, under master netting arrangements, amounts not offset in our condensed consolidated balance sheets, collateral Derivative Liability, Subject to Master Netting Arrangement, Collateral, Right to Reclaim Security Not Offset US Treasury US Treasury [Member] Represent the company's related transactions with the U.S. Treasury. Consolidation Items [Axis] Consolidation Items [Axis] 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 Collateral posted Collateral Already Posted, Aggregate Fair Value