XML 21 R78.htm IDEA: XBRL DOCUMENT v2.4.1.9
Segment Reporting (Details) (USD $)
In Millions, unless otherwise specified
3 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Segment Reporting Information [Line Items]    
Net interest income (loss) $ 5,067us-gaap_InterestIncomeExpenseNet $ 4,738us-gaap_InterestIncomeExpenseNet
Benefit for credit losses 533us-gaap_ProvisionForLoanLeaseAndOtherLosses 774us-gaap_ProvisionForLoanLeaseAndOtherLosses
Net interest income after benefit for credit losses 5,600us-gaap_InterestIncomeExpenseAfterProvisionForLoanLoss 5,512us-gaap_InterestIncomeExpenseAfterProvisionForLoanLoss
Guaranty fee income (expense) 31us-gaap_GuarantyFeeIncome 45us-gaap_GuarantyFeeIncome
Investment gains (losses), net 342us-gaap_GainLossOnInvestmentsExcludingOtherThanTemporaryImpairments 95us-gaap_GainLossOnInvestmentsExcludingOtherThanTemporaryImpairments
Fair value (losses) gains, net (1,919)fnm_FairValueGainsLossesNet (1,190)fnm_FairValueGainsLossesNet
Debt extinguishment gains, net 8us-gaap_GainsLossesOnExtinguishmentOfDebt 0us-gaap_GainsLossesOnExtinguishmentOfDebt
(Losses) gains from partnership investments 207us-gaap_IncomeLossFromEquityMethodInvestments 45us-gaap_IncomeLossFromEquityMethodInvestments
Fee and other income (expense) 277fnm_FeeAndOtherIncome 4,310fnm_FeeAndOtherIncome
Administrative expenses (723)us-gaap_GeneralAndAdministrativeExpense (672)us-gaap_GeneralAndAdministrativeExpense
Foreclosed property (expense) income (473)us-gaap_ForeclosedRealEstateExpense 262us-gaap_ForeclosedRealEstateExpense
TCCA Fees (382)fnm_SingleFamilyGuarantyFeeTemporaryPayrollTaxCutContinuationActOf2011 (322)fnm_SingleFamilyGuarantyFeeTemporaryPayrollTaxCutContinuationActOf2011
Other (expenses) income (210)fnm_OtherNoninterestExpenseExcludingPartnershipLosses (176)fnm_OtherNoninterestExpenseExcludingPartnershipLosses
Income before federal income taxes 2,758us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments 7,909us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments
Provision for federal income taxes (870)us-gaap_IncomeTaxExpenseBenefit (2,584)us-gaap_IncomeTaxExpenseBenefit
Net income attributable to Fannie Mae 1,888us-gaap_NetIncomeLoss 5,325us-gaap_NetIncomeLoss
Single-Family [Member]    
Segment Reporting Information [Line Items]    
Net interest income (loss) 9us-gaap_InterestIncomeExpenseNet
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_SingleFamilyMember
(48)us-gaap_InterestIncomeExpenseNet
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_SingleFamilyMember
Benefit for credit losses 478us-gaap_ProvisionForLoanLeaseAndOtherLosses
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_SingleFamilyMember
745us-gaap_ProvisionForLoanLeaseAndOtherLosses
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_SingleFamilyMember
Net interest income after benefit for credit losses 487us-gaap_InterestIncomeExpenseAfterProvisionForLoanLoss
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_SingleFamilyMember
697us-gaap_InterestIncomeExpenseAfterProvisionForLoanLoss
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_SingleFamilyMember
Guaranty fee income (expense) 3,040us-gaap_GuarantyFeeIncome
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_SingleFamilyMember
2,870us-gaap_GuarantyFeeIncome
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_SingleFamilyMember
Investment gains (losses), net 0us-gaap_GainLossOnInvestmentsExcludingOtherThanTemporaryImpairments
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_SingleFamilyMember
0us-gaap_GainLossOnInvestmentsExcludingOtherThanTemporaryImpairments
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_SingleFamilyMember
Fair value (losses) gains, net (4)fnm_FairValueGainsLossesNet
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_SingleFamilyMember
(5)fnm_FairValueGainsLossesNet
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_SingleFamilyMember
Debt extinguishment gains, net 0us-gaap_GainsLossesOnExtinguishmentOfDebt
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_SingleFamilyMember
0us-gaap_GainsLossesOnExtinguishmentOfDebt
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_SingleFamilyMember
(Losses) gains from partnership investments (5)us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_SingleFamilyMember
0us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_SingleFamilyMember
Fee and other income (expense) 172fnm_FeeAndOtherIncome
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_SingleFamilyMember
144fnm_FeeAndOtherIncome
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_SingleFamilyMember
Administrative expenses (484)us-gaap_GeneralAndAdministrativeExpense
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_SingleFamilyMember
(450)us-gaap_GeneralAndAdministrativeExpense
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_SingleFamilyMember
Foreclosed property (expense) income (485)us-gaap_ForeclosedRealEstateExpense
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_SingleFamilyMember
257us-gaap_ForeclosedRealEstateExpense
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_SingleFamilyMember
Other (expenses) income (227)fnm_OtherNoninterestExpenseExcludingPartnershipLosses
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_SingleFamilyMember
(155)fnm_OtherNoninterestExpenseExcludingPartnershipLosses
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_SingleFamilyMember
Income before federal income taxes 2,112us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_SingleFamilyMember
3,036us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_SingleFamilyMember
Provision for federal income taxes (581)us-gaap_IncomeTaxExpenseBenefit
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_SingleFamilyMember
(927)us-gaap_IncomeTaxExpenseBenefit
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_SingleFamilyMember
Net income attributable to Fannie Mae 1,531us-gaap_NetIncomeLoss
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_SingleFamilyMember
2,109us-gaap_NetIncomeLoss
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_SingleFamilyMember
Multifamily [Member]    
Segment Reporting Information [Line Items]    
Net interest income (loss) (31)us-gaap_InterestIncomeExpenseNet
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_MultifamilyMember
(22)us-gaap_InterestIncomeExpenseNet
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_MultifamilyMember
Benefit for credit losses 55us-gaap_ProvisionForLoanLeaseAndOtherLosses
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_MultifamilyMember
29us-gaap_ProvisionForLoanLeaseAndOtherLosses
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_MultifamilyMember
Net interest income after benefit for credit losses 24us-gaap_InterestIncomeExpenseAfterProvisionForLoanLoss
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_MultifamilyMember
7us-gaap_InterestIncomeExpenseAfterProvisionForLoanLoss
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_MultifamilyMember
Guaranty fee income (expense) 340us-gaap_GuarantyFeeIncome
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_MultifamilyMember
311us-gaap_GuarantyFeeIncome
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_MultifamilyMember
Investment gains (losses), net 9us-gaap_GainLossOnInvestmentsExcludingOtherThanTemporaryImpairments
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_MultifamilyMember
3us-gaap_GainLossOnInvestmentsExcludingOtherThanTemporaryImpairments
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_MultifamilyMember
Fair value (losses) gains, net 0fnm_FairValueGainsLossesNet
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_MultifamilyMember
0fnm_FairValueGainsLossesNet
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_MultifamilyMember
Debt extinguishment gains, net 0us-gaap_GainsLossesOnExtinguishmentOfDebt
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_MultifamilyMember
0us-gaap_GainsLossesOnExtinguishmentOfDebt
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_MultifamilyMember
(Losses) gains from partnership investments 212us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_MultifamilyMember
45us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_MultifamilyMember
Fee and other income (expense) 51fnm_FeeAndOtherIncome
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_MultifamilyMember
24fnm_FeeAndOtherIncome
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_MultifamilyMember
Administrative expenses (88)us-gaap_GeneralAndAdministrativeExpense
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_MultifamilyMember
(73)us-gaap_GeneralAndAdministrativeExpense
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_MultifamilyMember
Foreclosed property (expense) income 12us-gaap_ForeclosedRealEstateExpense
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_MultifamilyMember
5us-gaap_ForeclosedRealEstateExpense
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_MultifamilyMember
Other (expenses) income (7)fnm_OtherNoninterestExpenseExcludingPartnershipLosses
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_MultifamilyMember
(1)fnm_OtherNoninterestExpenseExcludingPartnershipLosses
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_MultifamilyMember
Income before federal income taxes 553us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_MultifamilyMember
321us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_MultifamilyMember
Provision for federal income taxes (70)us-gaap_IncomeTaxExpenseBenefit
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_MultifamilyMember
9us-gaap_IncomeTaxExpenseBenefit
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_MultifamilyMember
Net income attributable to Fannie Mae 483us-gaap_NetIncomeLoss
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_MultifamilyMember
330us-gaap_NetIncomeLoss
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_MultifamilyMember
Capital Markets [Member]    
Segment Reporting Information [Line Items]    
Net interest income (loss) 1,602us-gaap_InterestIncomeExpenseNet
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_CapitalMarketsMember
1,830us-gaap_InterestIncomeExpenseNet
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_CapitalMarketsMember
Benefit for credit losses 0us-gaap_ProvisionForLoanLeaseAndOtherLosses
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_CapitalMarketsMember
0us-gaap_ProvisionForLoanLeaseAndOtherLosses
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_CapitalMarketsMember
Net interest income after benefit for credit losses 1,602us-gaap_InterestIncomeExpenseAfterProvisionForLoanLoss
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_CapitalMarketsMember
1,830us-gaap_InterestIncomeExpenseAfterProvisionForLoanLoss
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_CapitalMarketsMember
Guaranty fee income (expense) (227)us-gaap_GuarantyFeeIncome
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_CapitalMarketsMember
(246)us-gaap_GuarantyFeeIncome
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_CapitalMarketsMember
Investment gains (losses), net 1,509us-gaap_GainLossOnInvestmentsExcludingOtherThanTemporaryImpairments
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_CapitalMarketsMember
1,285us-gaap_GainLossOnInvestmentsExcludingOtherThanTemporaryImpairments
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_CapitalMarketsMember
Fair value (losses) gains, net (1,970)fnm_FairValueGainsLossesNet
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_CapitalMarketsMember
(1,337)fnm_FairValueGainsLossesNet
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_CapitalMarketsMember
Debt extinguishment gains, net 2us-gaap_GainsLossesOnExtinguishmentOfDebt
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_CapitalMarketsMember
(7)us-gaap_GainsLossesOnExtinguishmentOfDebt
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_CapitalMarketsMember
(Losses) gains from partnership investments 0us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_CapitalMarketsMember
0us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_CapitalMarketsMember
Fee and other income (expense) 55fnm_FeeAndOtherIncome
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_CapitalMarketsMember
4,133fnm_FeeAndOtherIncome
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_CapitalMarketsMember
Administrative expenses (151)us-gaap_GeneralAndAdministrativeExpense
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_CapitalMarketsMember
(149)us-gaap_GeneralAndAdministrativeExpense
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_CapitalMarketsMember
Foreclosed property (expense) income 0us-gaap_ForeclosedRealEstateExpense
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_CapitalMarketsMember
0us-gaap_ForeclosedRealEstateExpense
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_CapitalMarketsMember
Other (expenses) income (2)fnm_OtherNoninterestExpenseExcludingPartnershipLosses
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_CapitalMarketsMember
(8)fnm_OtherNoninterestExpenseExcludingPartnershipLosses
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_CapitalMarketsMember
Income before federal income taxes 818us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_CapitalMarketsMember
5,501us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_CapitalMarketsMember
Provision for federal income taxes (219)us-gaap_IncomeTaxExpenseBenefit
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_CapitalMarketsMember
(1,666)us-gaap_IncomeTaxExpenseBenefit
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_CapitalMarketsMember
Net income attributable to Fannie Mae 599us-gaap_NetIncomeLoss
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_CapitalMarketsMember
3,835us-gaap_NetIncomeLoss
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_CapitalMarketsMember
Consolidated Trusts [Member]    
Segment Reporting Information [Line Items]    
Net interest income (loss) 3,216us-gaap_InterestIncomeExpenseNet
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
2,698us-gaap_InterestIncomeExpenseNet
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
Benefit for credit losses 0us-gaap_ProvisionForLoanLeaseAndOtherLosses
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
0us-gaap_ProvisionForLoanLeaseAndOtherLosses
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
Net interest income after benefit for credit losses 3,216us-gaap_InterestIncomeExpenseAfterProvisionForLoanLoss
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
2,698us-gaap_InterestIncomeExpenseAfterProvisionForLoanLoss
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
Guaranty fee income (expense) (1,562)us-gaap_GuarantyFeeIncome
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
(1,427)us-gaap_GuarantyFeeIncome
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
Investment gains (losses), net (202)us-gaap_GainLossOnInvestmentsExcludingOtherThanTemporaryImpairments
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
(58)us-gaap_GainLossOnInvestmentsExcludingOtherThanTemporaryImpairments
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
Fair value (losses) gains, net (2)fnm_FairValueGainsLossesNet
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
48fnm_FairValueGainsLossesNet
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
Debt extinguishment gains, net 6us-gaap_GainsLossesOnExtinguishmentOfDebt
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
7us-gaap_GainsLossesOnExtinguishmentOfDebt
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
(Losses) gains from partnership investments 0us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
0us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
Fee and other income (expense) (79)fnm_FeeAndOtherIncome
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
(76)fnm_FeeAndOtherIncome
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
Administrative expenses 0us-gaap_GeneralAndAdministrativeExpense
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
0us-gaap_GeneralAndAdministrativeExpense
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
Foreclosed property (expense) income 0us-gaap_ForeclosedRealEstateExpense
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
0us-gaap_ForeclosedRealEstateExpense
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
Other (expenses) income 0fnm_OtherNoninterestExpenseExcludingPartnershipLosses
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
0fnm_OtherNoninterestExpenseExcludingPartnershipLosses
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
Income before federal income taxes 1,377us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
1,192us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
Provision for federal income taxes 0us-gaap_IncomeTaxExpenseBenefit
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
0us-gaap_IncomeTaxExpenseBenefit
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
Net income attributable to Fannie Mae 1,377us-gaap_NetIncomeLoss
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
1,192us-gaap_NetIncomeLoss
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
Eliminations/Adjustments [Member]    
Segment Reporting Information [Line Items]    
Net interest income (loss) 271us-gaap_InterestIncomeExpenseNet
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_MaterialReconcilingItemsMember
280us-gaap_InterestIncomeExpenseNet
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_MaterialReconcilingItemsMember
Benefit for credit losses 0us-gaap_ProvisionForLoanLeaseAndOtherLosses
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_MaterialReconcilingItemsMember
0us-gaap_ProvisionForLoanLeaseAndOtherLosses
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_MaterialReconcilingItemsMember
Net interest income after benefit for credit losses 271us-gaap_InterestIncomeExpenseAfterProvisionForLoanLoss
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_MaterialReconcilingItemsMember
280us-gaap_InterestIncomeExpenseAfterProvisionForLoanLoss
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_MaterialReconcilingItemsMember
Guaranty fee income (expense) (1,560)us-gaap_GuarantyFeeIncome
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_MaterialReconcilingItemsMember
(1,463)us-gaap_GuarantyFeeIncome
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_MaterialReconcilingItemsMember
Investment gains (losses), net (974)us-gaap_GainLossOnInvestmentsExcludingOtherThanTemporaryImpairments
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_MaterialReconcilingItemsMember
(1,135)us-gaap_GainLossOnInvestmentsExcludingOtherThanTemporaryImpairments
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_MaterialReconcilingItemsMember
Fair value (losses) gains, net 57fnm_FairValueGainsLossesNet
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_MaterialReconcilingItemsMember
104fnm_FairValueGainsLossesNet
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_MaterialReconcilingItemsMember
Debt extinguishment gains, net 0us-gaap_GainsLossesOnExtinguishmentOfDebt
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_MaterialReconcilingItemsMember
0us-gaap_GainsLossesOnExtinguishmentOfDebt
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_MaterialReconcilingItemsMember
(Losses) gains from partnership investments 0us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_MaterialReconcilingItemsMember
0us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_MaterialReconcilingItemsMember
Fee and other income (expense) 78fnm_FeeAndOtherIncome
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_MaterialReconcilingItemsMember
85fnm_FeeAndOtherIncome
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_MaterialReconcilingItemsMember
Administrative expenses 0us-gaap_GeneralAndAdministrativeExpense
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_MaterialReconcilingItemsMember
0us-gaap_GeneralAndAdministrativeExpense
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_MaterialReconcilingItemsMember
Foreclosed property (expense) income 0us-gaap_ForeclosedRealEstateExpense
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_MaterialReconcilingItemsMember
0us-gaap_ForeclosedRealEstateExpense
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_MaterialReconcilingItemsMember
Other (expenses) income 26fnm_OtherNoninterestExpenseExcludingPartnershipLosses
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_MaterialReconcilingItemsMember
(12)fnm_OtherNoninterestExpenseExcludingPartnershipLosses
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_MaterialReconcilingItemsMember
Income before federal income taxes (2,102)us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_MaterialReconcilingItemsMember
(2,141)us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_MaterialReconcilingItemsMember
Provision for federal income taxes 0us-gaap_IncomeTaxExpenseBenefit
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_MaterialReconcilingItemsMember
0us-gaap_IncomeTaxExpenseBenefit
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_MaterialReconcilingItemsMember
Net income attributable to Fannie Mae (2,102)us-gaap_NetIncomeLoss
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_MaterialReconcilingItemsMember
(2,141)us-gaap_NetIncomeLoss
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_MaterialReconcilingItemsMember
US Treasury [Member]    
Segment Reporting Information [Line Items]    
TCCA Fees (382)fnm_SingleFamilyGuarantyFeeTemporaryPayrollTaxCutContinuationActOf2011
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= fnm_UsTreasuryMember
(322)fnm_SingleFamilyGuarantyFeeTemporaryPayrollTaxCutContinuationActOf2011
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= fnm_UsTreasuryMember
US Treasury [Member] | Single-Family [Member]    
Segment Reporting Information [Line Items]    
TCCA Fees $ (382)fnm_SingleFamilyGuarantyFeeTemporaryPayrollTaxCutContinuationActOf2011
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= fnm_UsTreasuryMember
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_SingleFamilyMember
$ (322)fnm_SingleFamilyGuarantyFeeTemporaryPayrollTaxCutContinuationActOf2011
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= fnm_UsTreasuryMember
/ us-gaap_StatementBusinessSegmentsAxis
= fnm_SingleFamilyMember