0001423689-25-000056 | 10-Q | XBRL Viewer

Pledged Assets (Narrative) (Details) - USD ($) $ in Millions	Mar. 31, 2025	Dec. 31, 2024
Pledged Assets [Abstract]
Retained Interests in Consolidated VIE's Pledged as Collateral Under Repurchase Agreements	$ 33	$ 33

Label	Element	Value
Available For Sale Securities Par	agnc_AvailableForSaleSecuritiesPar	$ 4,313,000,000
Available For Sale Securities Par	agnc_AvailableForSaleSecuritiesPar	4,313,000,000
Available For Sale Securities Par	agnc_AvailableForSaleSecuritiesPar	4,447,000,000
Available For Sale Securities Par	agnc_AvailableForSaleSecuritiesPar	4,447,000,000
government bonds owned and sold short net	agnc_Governmentbondsownedandsoldshortnet	(13,900,000,000)
government bonds owned and sold short net	agnc_Governmentbondsownedandsoldshortnet	(15,101,000,000)
government bonds owned and sold short net	agnc_Governmentbondsownedandsoldshortnet	(1,056,000,000)
government bonds owned and sold short net	agnc_Governmentbondsownedandsoldshortnet	(1,058,000,000)
government bonds owned and sold short net	agnc_Governmentbondsownedandsoldshortnet	956,000,000
government bonds owned and sold short net	agnc_Governmentbondsownedandsoldshortnet	956,000,000
government bonds owned and sold short net	agnc_Governmentbondsownedandsoldshortnet	(671,000,000)
government bonds owned and sold short net	agnc_Governmentbondsownedandsoldshortnet	(507,000,000)
government bonds owned and sold short net	agnc_Governmentbondsownedandsoldshortnet	(2,722,000,000)
government bonds owned and sold short net	agnc_Governmentbondsownedandsoldshortnet	(2,302,000,000)
government bonds owned and sold short net	agnc_Governmentbondsownedandsoldshortnet	(10,910,000,000)
government bonds owned and sold short net	agnc_Governmentbondsownedandsoldshortnet	(10,526,000,000)
government bonds owned and sold short net	agnc_Governmentbondsownedandsoldshortnet	(12,659,000,000)
government bonds owned and sold short net	agnc_Governmentbondsownedandsoldshortnet	(11,999,000,000)
government bonds owned and sold short net	agnc_Governmentbondsownedandsoldshortnet	(1,783,000,000)
government bonds owned and sold short net	agnc_Governmentbondsownedandsoldshortnet	(1,809,000,000)
government bonds owned and sold short net	agnc_Governmentbondsownedandsoldshortnet	(1,782,000,000)
government bonds owned and sold short net	agnc_Governmentbondsownedandsoldshortnet	(1,756,000,000)
government bonds owned and sold short net	agnc_Governmentbondsownedandsoldshortnet	(14,420,000,000)
government bonds owned and sold short net	agnc_Governmentbondsownedandsoldshortnet	(13,900,000,000)
government bonds owned and sold short net	agnc_Governmentbondsownedandsoldshortnet	(16,207,000,000)
government bonds owned and sold short net	agnc_Governmentbondsownedandsoldshortnet	(15,101,000,000)
government bonds owned and sold short net	agnc_Governmentbondsownedandsoldshortnet	3,300,000,000
government bonds owned and sold short net	agnc_Governmentbondsownedandsoldshortnet	1,600,000,000
Debt Securities, Trading and Available-for-sale, Amortized Cost Basis	agnc_DebtSecuritiesTradingandAvailableforsaleAmortizedCostBasis	70,307,000,000
Debt Securities, Trading and Available-for-sale, Amortized Cost Basis	agnc_DebtSecuritiesTradingandAvailableforsaleAmortizedCostBasis	67,139,000,000
Debt Securities, Trading and Available-for-sale, Amortized Cost Basis	agnc_DebtSecuritiesTradingandAvailableforsaleAmortizedCostBasis	783,000,000
Debt Securities, Trading and Available-for-sale, Amortized Cost Basis	agnc_DebtSecuritiesTradingandAvailableforsaleAmortizedCostBasis	796,000,000
Debt Securities, Trading and Available-for-sale, Amortized Cost Basis	agnc_DebtSecuritiesTradingandAvailableforsaleAmortizedCostBasis	96,000,000
Debt Securities, Trading and Available-for-sale, Amortized Cost Basis	agnc_DebtSecuritiesTradingandAvailableforsaleAmortizedCostBasis	102,000,000
Debt Securities, Trading and Available-for-sale, Amortized Cost Basis	agnc_DebtSecuritiesTradingandAvailableforsaleAmortizedCostBasis	82,000,000
Debt Securities, Trading and Available-for-sale, Amortized Cost Basis	agnc_DebtSecuritiesTradingandAvailableforsaleAmortizedCostBasis	60,000,000
Debt Securities, Trading and Available-for-sale, Amortized Cost Basis	agnc_DebtSecuritiesTradingandAvailableforsaleAmortizedCostBasis	1,033,000,000
Debt Securities, Trading and Available-for-sale, Amortized Cost Basis	agnc_DebtSecuritiesTradingandAvailableforsaleAmortizedCostBasis	485,000,000
Debt Securities, Trading and Available-for-sale, Amortized Cost Basis	agnc_DebtSecuritiesTradingandAvailableforsaleAmortizedCostBasis	72,301,000,000
Debt Securities, Trading and Available-for-sale, Amortized Cost Basis	agnc_DebtSecuritiesTradingandAvailableforsaleAmortizedCostBasis	68,582,000,000
Debt Securities, Trading and Available-for-sale, Amortized Cost Basis	agnc_DebtSecuritiesTradingandAvailableforsaleAmortizedCostBasis	17,000,000
Debt Securities, Trading and Available-for-sale, Amortized Cost Basis	agnc_DebtSecuritiesTradingandAvailableforsaleAmortizedCostBasis	17,000,000
Debt Securities, Trading and Available-for-sale, Amortized Cost Basis	agnc_DebtSecuritiesTradingandAvailableforsaleAmortizedCostBasis	235,000,000
Debt Securities, Trading and Available-for-sale, Amortized Cost Basis	agnc_DebtSecuritiesTradingandAvailableforsaleAmortizedCostBasis	264,000,000
Debt Securities, Trading and Available-for-sale, Amortized Cost Basis	agnc_DebtSecuritiesTradingandAvailableforsaleAmortizedCostBasis	595,000,000
Debt Securities, Trading and Available-for-sale, Amortized Cost Basis	agnc_DebtSecuritiesTradingandAvailableforsaleAmortizedCostBasis	583,000,000
Debt Securities, Trading and Available-for-sale, Amortized Cost Basis	agnc_DebtSecuritiesTradingandAvailableforsaleAmortizedCostBasis	73,148,000,000
Debt Securities, Trading and Available-for-sale, Amortized Cost Basis	agnc_DebtSecuritiesTradingandAvailableforsaleAmortizedCostBasis	69,446,000,000
Available For Sale Securities Weighted Average Life Amortized Cost	agnc_AvailableForSaleSecuritiesWeightedAverageLifeAmortizedCost	548,000,000
Available For Sale Securities Weighted Average Life Amortized Cost	agnc_AvailableForSaleSecuritiesWeightedAverageLifeAmortizedCost	530,000,000
Available For Sale Securities Weighted Average Life Amortized Cost	agnc_AvailableForSaleSecuritiesWeightedAverageLifeAmortizedCost	5,611,000,000
Available For Sale Securities Weighted Average Life Amortized Cost	agnc_AvailableForSaleSecuritiesWeightedAverageLifeAmortizedCost	2,066,000,000
Available For Sale Securities Weighted Average Life Amortized Cost	agnc_AvailableForSaleSecuritiesWeightedAverageLifeAmortizedCost	63,212,000,000
Available For Sale Securities Weighted Average Life Amortized Cost	agnc_AvailableForSaleSecuritiesWeightedAverageLifeAmortizedCost	59,479,000,000
Available For Sale Securities Weighted Average Life Amortized Cost	agnc_AvailableForSaleSecuritiesWeightedAverageLifeAmortizedCost	3,777,000,000
Available For Sale Securities Weighted Average Life Amortized Cost	agnc_AvailableForSaleSecuritiesWeightedAverageLifeAmortizedCost	7,371,000,000
Available For Sale Securities Weighted Average Life Amortized Cost	agnc_AvailableForSaleSecuritiesWeightedAverageLifeAmortizedCost	73,148,000,000
Available For Sale Securities Weighted Average Life Amortized Cost	agnc_AvailableForSaleSecuritiesWeightedAverageLifeAmortizedCost	69,446,000,000
Derivative, Forward Settlement Value	agnc_DerivativeForwardSettlementValue	1,784,000,000
Derivative, Forward Settlement Value	agnc_DerivativeForwardSettlementValue	4,969,000,000
Derivative, Forward Settlement Value	agnc_DerivativeForwardSettlementValue	7,429,000,000
Derivative, Forward Settlement Value	agnc_DerivativeForwardSettlementValue	6,887,000,000
Debt Securities, Trading Securities, Unamortized Discount	agnc_DebtSecuritiesTradingSecuritiesUnamortizedDiscount	380,000,000
Debt Securities, Trading Securities, Unamortized Discount	agnc_DebtSecuritiesTradingSecuritiesUnamortizedDiscount	3,000,000
Debt Securities, Trading Securities, Unamortized Discount	agnc_DebtSecuritiesTradingSecuritiesUnamortizedDiscount	5,000,000
Debt Securities, Trading Securities, Unamortized Discount	agnc_DebtSecuritiesTradingSecuritiesUnamortizedDiscount	399,000,000
Debt Securities, Trading Securities, Unamortized Discount	agnc_DebtSecuritiesTradingSecuritiesUnamortizedDiscount	374,000,000
Debt Securities, Trading Securities, Unamortized Discount	agnc_DebtSecuritiesTradingSecuritiesUnamortizedDiscount	3,000,000
Debt Securities, Trading Securities, Unamortized Discount	agnc_DebtSecuritiesTradingSecuritiesUnamortizedDiscount	8,000,000
Debt Securities, Trading Securities, Unamortized Discount	agnc_DebtSecuritiesTradingSecuritiesUnamortizedDiscount	396,000,000
Common stock, Value of Shares Remaining for Future Issuance	agnc_CommonstockValueofSharesRemainingforFutureIssuance	700,000,000
Common stock, Value of Shares Remaining for Future Issuance	agnc_CommonstockValueofSharesRemainingforFutureIssuance	1,500,000,000
Loss On Derivative Instruments And Trading Securities Net	agnc_LossOnDerivativeInstrumentsAndTradingSecuritiesNet	1,019,000,000
Loss On Derivative Instruments And Trading Securities Net	agnc_LossOnDerivativeInstrumentsAndTradingSecuritiesNet	(1,059,000,000)
Trading Securities Par	agnc_TradingSecuritiesPar	66,974,000,000
Trading Securities Par	agnc_TradingSecuritiesPar	19,000,000
Trading Securities Par	agnc_TradingSecuritiesPar	238,000,000
Trading Securities Par	agnc_TradingSecuritiesPar	67,817,000,000
Trading Securities Par	agnc_TradingSecuritiesPar	63,119,000,000
Trading Securities Par	agnc_TradingSecuritiesPar	19,000,000
Trading Securities Par	agnc_TradingSecuritiesPar	270,000,000
Trading Securities Par	agnc_TradingSecuritiesPar	63,984,000,000
Trading Securities Par	agnc_TradingSecuritiesPar	1,975,000,000
Trading Securities Par	agnc_TradingSecuritiesPar	307,000,000
Trading Securities Par	agnc_TradingSecuritiesPar	93,000,000
Trading Securities Par	agnc_TradingSecuritiesPar	93,000,000
Notional Amount Of Trading Securities Settlement Expiration During The Period	agnc_NotionalAmountOfTradingSecuritiesSettlementExpirationDuringThePeriod	(3,757,000,000)
Notional Amount Of Trading Securities Settlement Expiration During The Period	agnc_NotionalAmountOfTradingSecuritiesSettlementExpirationDuringThePeriod	(1,346,000,000)
Notional Amount Of Derivatives Not Designated As Hedging Instruments Additions During The Period	agnc_NotionalAmountOfDerivativesNotDesignatedAsHedgingInstrumentsAdditionsDuringPeriod	27,967,000,000
Notional Amount Of Derivatives Not Designated As Hedging Instruments Additions During The Period	agnc_NotionalAmountOfDerivativesNotDesignatedAsHedgingInstrumentsAdditionsDuringPeriod	8,150,000,000
Notional Amount Of Derivatives Not Designated As Hedging Instruments Additions During The Period	agnc_NotionalAmountOfDerivativesNotDesignatedAsHedgingInstrumentsAdditionsDuringPeriod	1,500,000,000
Notional Amount Of Derivatives Not Designated As Hedging Instruments Additions During The Period	agnc_NotionalAmountOfDerivativesNotDesignatedAsHedgingInstrumentsAdditionsDuringPeriod	0
Notional Amount Of Derivatives Not Designated As Hedging Instruments Additions During The Period	agnc_NotionalAmountOfDerivativesNotDesignatedAsHedgingInstrumentsAdditionsDuringPeriod	3,821,000,000
Notional Amount Of Derivatives Not Designated As Hedging Instruments Additions During The Period	agnc_NotionalAmountOfDerivativesNotDesignatedAsHedgingInstrumentsAdditionsDuringPeriod	(1,441,000,000)
Notional Amount Of Derivatives Not Designated As Hedging Instruments Additions During The Period	agnc_NotionalAmountOfDerivativesNotDesignatedAsHedgingInstrumentsAdditionsDuringPeriod	25,390,000,000
Notional Amount Of Derivatives Not Designated As Hedging Instruments Additions During The Period	agnc_NotionalAmountOfDerivativesNotDesignatedAsHedgingInstrumentsAdditionsDuringPeriod	5,170,000,000
Notional Amount Of Derivatives Not Designated As Hedging Instruments Additions During The Period	agnc_NotionalAmountOfDerivativesNotDesignatedAsHedgingInstrumentsAdditionsDuringPeriod	0
Notional Amount Of Derivatives Not Designated As Hedging Instruments Additions During The Period	agnc_NotionalAmountOfDerivativesNotDesignatedAsHedgingInstrumentsAdditionsDuringPeriod	0
Notional Amount Of Derivatives Not Designated As Hedging Instruments Additions During The Period	agnc_NotionalAmountOfDerivativesNotDesignatedAsHedgingInstrumentsAdditionsDuringPeriod	0
Notional Amount Of Derivatives Not Designated As Hedging Instruments Additions During The Period	agnc_NotionalAmountOfDerivativesNotDesignatedAsHedgingInstrumentsAdditionsDuringPeriod	0
Notional Amount Of Derivatives Not Designated As Hedging Instruments Additions During The Period	agnc_NotionalAmountOfDerivativesNotDesignatedAsHedgingInstrumentsAdditionsDuringPeriod	3,101,000,000
Notional Amount Of Derivatives Not Designated As Hedging Instruments Additions During The Period	agnc_NotionalAmountOfDerivativesNotDesignatedAsHedgingInstrumentsAdditionsDuringPeriod	3,384,000,000
Proceeds from Sale of Debt Securities, Trading	agnc_ProceedsFromSaleOfDebtSecuritiesTrading	3,160,000,000
Proceeds from Sale of Debt Securities, Trading	agnc_ProceedsFromSaleOfDebtSecuritiesTrading	5,127,000,000
Non-Agency Securities, at Fair Value	agnc_NonAgencySecuritiesatFairValue	290,000,000
Non-Agency Securities, at Fair Value	agnc_NonAgencySecuritiesatFairValue	315,000,000
Available For Sale Securities Weighted Average Life Fair Value	agnc_AvailableForSaleSecuritiesWeightedAverageLifeFairValue	536,000,000
Available For Sale Securities Weighted Average Life Fair Value	agnc_AvailableForSaleSecuritiesWeightedAverageLifeFairValue	539,000,000
Available For Sale Securities Weighted Average Life Fair Value	agnc_AvailableForSaleSecuritiesWeightedAverageLifeFairValue	5,660,000,000
Available For Sale Securities Weighted Average Life Fair Value	agnc_AvailableForSaleSecuritiesWeightedAverageLifeFairValue	2,026,000,000
Available For Sale Securities Weighted Average Life Fair Value	agnc_AvailableForSaleSecuritiesWeightedAverageLifeFairValue	61,379,000,000
Available For Sale Securities Weighted Average Life Fair Value	agnc_AvailableForSaleSecuritiesWeightedAverageLifeFairValue	56,551,000,000
Available For Sale Securities Weighted Average Life Fair Value	agnc_AvailableForSaleSecuritiesWeightedAverageLifeFairValue	3,750,000,000
Available For Sale Securities Weighted Average Life Fair Value	agnc_AvailableForSaleSecuritiesWeightedAverageLifeFairValue	7,232,000,000
Available For Sale Securities Weighted Average Life Fair Value	agnc_AvailableForSaleSecuritiesWeightedAverageLifeFairValue	71,325,000,000
Available For Sale Securities Weighted Average Life Fair Value	agnc_AvailableForSaleSecuritiesWeightedAverageLifeFairValue	66,348,000,000
Proceeds from Sale of Debt Securities	agnc_ProceedsFromSaleOfDebtSecurities	3,160,000,000
Proceeds from Sale of Debt Securities	agnc_ProceedsFromSaleOfDebtSecurities	5,127,000,000
Debt Securities, Available-for-Sale, Unamortized Discount	agnc_DebtSecuritiesAvailableForSaleUnamortizedDiscount	1,000,000
Debt Securities, Available-for-Sale, Unamortized Discount	agnc_DebtSecuritiesAvailableForSaleUnamortizedDiscount	1,000,000
Debt Securities, Available-for-Sale, Unamortized Discount	agnc_DebtSecuritiesAvailableForSaleUnamortizedDiscount	1,000,000
Debt Securities, Available-for-Sale, Unamortized Discount	agnc_DebtSecuritiesAvailableForSaleUnamortizedDiscount	$ 1,000,000
Weighted Average Number of Shares Outstanding	agnc_WeightedAverageNumberofSharesOutstanding	916,100,000
Weighted Average Number of Shares Outstanding	agnc_WeightedAverageNumberofSharesOutstanding	700,100,000
Notional Amount Of Derivatives Not Designated As Hedging Instruments Settlement Expiration During The Period	agnc_NotionalAmountOfDerivativesNotDesignatedAsHedgingInstrumentsSettlementExpirationDuringPeriod	$ (27,111,000,000)
Notional Amount Of Derivatives Not Designated As Hedging Instruments Settlement Expiration During The Period	agnc_NotionalAmountOfDerivativesNotDesignatedAsHedgingInstrumentsSettlementExpirationDuringPeriod	0
Notional Amount Of Derivatives Not Designated As Hedging Instruments Settlement Expiration During The Period	agnc_NotionalAmountOfDerivativesNotDesignatedAsHedgingInstrumentsSettlementExpirationDuringPeriod	(1,500,000,000)
Notional Amount Of Derivatives Not Designated As Hedging Instruments Settlement Expiration During The Period	agnc_NotionalAmountOfDerivativesNotDesignatedAsHedgingInstrumentsSettlementExpirationDuringPeriod	0
Notional Amount Of Derivatives Not Designated As Hedging Instruments Settlement Expiration During The Period	agnc_NotionalAmountOfDerivativesNotDesignatedAsHedgingInstrumentsSettlementExpirationDuringPeriod	(3,977,000,000)
Notional Amount Of Derivatives Not Designated As Hedging Instruments Settlement Expiration During The Period	agnc_NotionalAmountOfDerivativesNotDesignatedAsHedgingInstrumentsSettlementExpirationDuringPeriod	4,291,000,000
Notional Amount Of Derivatives Not Designated As Hedging Instruments Settlement Expiration During The Period	agnc_NotionalAmountOfDerivativesNotDesignatedAsHedgingInstrumentsSettlementExpirationDuringPeriod	(22,071,000,000)
Notional Amount Of Derivatives Not Designated As Hedging Instruments Settlement Expiration During The Period	agnc_NotionalAmountOfDerivativesNotDesignatedAsHedgingInstrumentsSettlementExpirationDuringPeriod	(5,250,000,000)
Notional Amount Of Derivatives Not Designated As Hedging Instruments Settlement Expiration During The Period	agnc_NotionalAmountOfDerivativesNotDesignatedAsHedgingInstrumentsSettlementExpirationDuringPeriod	0
Notional Amount Of Derivatives Not Designated As Hedging Instruments Settlement Expiration During The Period	agnc_NotionalAmountOfDerivativesNotDesignatedAsHedgingInstrumentsSettlementExpirationDuringPeriod	0
Notional Amount Of Derivatives Not Designated As Hedging Instruments Settlement Expiration During The Period	agnc_NotionalAmountOfDerivativesNotDesignatedAsHedgingInstrumentsSettlementExpirationDuringPeriod	(1,250,000,000)
Notional Amount Of Derivatives Not Designated As Hedging Instruments Settlement Expiration During The Period	agnc_NotionalAmountOfDerivativesNotDesignatedAsHedgingInstrumentsSettlementExpirationDuringPeriod	0
Notional Amount Of Derivatives Not Designated As Hedging Instruments Settlement Expiration During The Period	agnc_NotionalAmountOfDerivativesNotDesignatedAsHedgingInstrumentsSettlementExpirationDuringPeriod	(1,641,000,000)
Notional Amount Of Derivatives Not Designated As Hedging Instruments Settlement Expiration During The Period	agnc_NotionalAmountOfDerivativesNotDesignatedAsHedgingInstrumentsSettlementExpirationDuringPeriod	$ (6,774,000,000)
Weighted Average Number of Fully Vested Restricted Stock Units and Performance Share Units Outstanding	agnc_WeightedAverageNumberofFullyVestedRestrictedStockUnitsandPerformanceShareUnitsOutstanding	2,200,000
Weighted Average Number of Fully Vested Restricted Stock Units and Performance Share Units Outstanding	agnc_WeightedAverageNumberofFullyVestedRestrictedStockUnitsandPerformanceShareUnitsOutstanding	2,100,000
Payments to Acquire U.S. Treasury securities	agnc_PaymentsToAcquireUSTreasurySecurities	$ 9,578,000,000
Payments to Acquire U.S. Treasury securities	agnc_PaymentsToAcquireUSTreasurySecurities	3,387,000,000
Debt Securities, Available-for-Sale, Unamortized Premium	agnc_DebtSecuritiesAvailableForSaleUnamortizedPremium	260,000,000
Debt Securities, Available-for-Sale, Unamortized Premium	agnc_DebtSecuritiesAvailableForSaleUnamortizedPremium	260,000,000
Debt Securities, Available-for-Sale, Unamortized Premium	agnc_DebtSecuritiesAvailableForSaleUnamortizedPremium	265,000,000
Debt Securities, Available-for-Sale, Unamortized Premium	agnc_DebtSecuritiesAvailableForSaleUnamortizedPremium	265,000,000
Net unrealized gain (loss) on investment securities measured at fair value through net income	agnc_Netunrealizedgainlossoninvestmentsecuritiesmeasuredatfairvaluethroughnetincome	(1,183,000,000)
Net unrealized gain (loss) on investment securities measured at fair value through net income	agnc_Netunrealizedgainlossoninvestmentsecuritiesmeasuredatfairvaluethroughnetincome	471,000,000
Principal collections on credit risk transfer and non-Agency securities	agnc_PrincipalcollectionsoncreditrisktransferandnonAgencysecurities	6,000,000
Principal collections on credit risk transfer and non-Agency securities	agnc_PrincipalcollectionsoncreditrisktransferandnonAgencysecurities	12,000,000
Cost of Sale of Investment Securities	agnc_CostofSaleofInvestmentSecurities	3,405,000,000
Cost of Sale of Investment Securities	agnc_CostofSaleofInvestmentSecurities	5,218,000,000
Net Fair Value of Interest Rate Swaps Excluding the Recognition of Variation Margin Settlements as a Reduction of Carrying Value	agnc_NetFairValueOfInterestRateSwapsExcludingTheRecognitionOfVariationMarginSettlementsAsAReductionOfCarryingValue	1,400,000,000
Net Fair Value of Interest Rate Swaps Excluding the Recognition of Variation Margin Settlements as a Reduction of Carrying Value	agnc_NetFairValueOfInterestRateSwapsExcludingTheRecognitionOfVariationMarginSettlementsAsAReductionOfCarryingValue	2,300,000,000
Debt Securities, Trading Securities, Unamortized Premium	agnc_DebtSecuritiesTradingSecuritiesUnamortizedPremium	1,135,000,000
Debt Securities, Trading Securities, Unamortized Premium	agnc_DebtSecuritiesTradingSecuritiesUnamortizedPremium	1,000,000
Debt Securities, Trading Securities, Unamortized Premium	agnc_DebtSecuritiesTradingSecuritiesUnamortizedPremium	2,000,000
Debt Securities, Trading Securities, Unamortized Premium	agnc_DebtSecuritiesTradingSecuritiesUnamortizedPremium	1,158,000,000
Debt Securities, Trading Securities, Unamortized Premium	agnc_DebtSecuritiesTradingSecuritiesUnamortizedPremium	1,126,000,000
Debt Securities, Trading Securities, Unamortized Premium	agnc_DebtSecuritiesTradingSecuritiesUnamortizedPremium	1,000,000
Debt Securities, Trading Securities, Unamortized Premium	agnc_DebtSecuritiesTradingSecuritiesUnamortizedPremium	2,000,000
Debt Securities, Trading Securities, Unamortized Premium	agnc_DebtSecuritiesTradingSecuritiesUnamortizedPremium	$ 1,147,000,000
Transfers Between Hierarchy Levels	agnc_TransfersBetweenHierarchyLevels	no
Preferred Stock D, Liquidation Preference, Value	agnc_PreferredStockDLiquidationPreferenceValue	$ 235,000,000
Preferred Stock D, Value, Issued	agnc_PreferredStockDValueIssued	227,000,000
Debt Securities, Trading Securities, Gross Unrealized Losses	agnc_DebtSecuritiesTradingSecuritiesGrossUnrealizedLosses	1,721,000,000
Debt Securities, Trading Securities, Gross Unrealized Losses	agnc_DebtSecuritiesTradingSecuritiesGrossUnrealizedLosses	2,000,000
Debt Securities, Trading Securities, Gross Unrealized Losses	agnc_DebtSecuritiesTradingSecuritiesGrossUnrealizedLosses	26,000,000
Debt Securities, Trading Securities, Gross Unrealized Losses	agnc_DebtSecuritiesTradingSecuritiesGrossUnrealizedLosses	1,749,000,000
Debt Securities, Trading Securities, Gross Unrealized Losses	agnc_DebtSecuritiesTradingSecuritiesGrossUnrealizedLosses	2,620,000,000
Debt Securities, Trading Securities, Gross Unrealized Losses	agnc_DebtSecuritiesTradingSecuritiesGrossUnrealizedLosses	2,000,000
Debt Securities, Trading Securities, Gross Unrealized Losses	agnc_DebtSecuritiesTradingSecuritiesGrossUnrealizedLosses	32,000,000
Debt Securities, Trading Securities, Gross Unrealized Losses	agnc_DebtSecuritiesTradingSecuritiesGrossUnrealizedLosses	2,654,000,000
Preferred Stock F, Value, Issued	agnc_PreferredStockFValueIssued	557,000,000
Comprehensive income available to common shareholders	agnc_ComprehensiveIncomeAvailableToCommonShareholders	108,000,000
Comprehensive income available to common shareholders	agnc_ComprehensiveIncomeAvailableToCommonShareholders	335,000,000
Proceeds From Principal Collection Of Mortgage Backed Securities Categorized As Available For Sale	agnc_ProceedsFromPrincipalCollectionOfMortgageBackedSecuritiesCategorizedAsAvailableForSale	1,538,000,000
Proceeds From Principal Collection Of Mortgage Backed Securities Categorized As Available For Sale	agnc_ProceedsFromPrincipalCollectionOfMortgageBackedSecuritiesCategorizedAsAvailableForSale	1,065,000,000
Trading Securities Added During the Period	agnc_TradingSecuritiesAddedDuringthePeriod	5,388,000,000
Trading Securities Added During the Period	agnc_TradingSecuritiesAddedDuringthePeriod	$ 1,669,000,000
Weighted Average Forward Start Days	agnc_WeightedAverageForwardStartDays	1
Weighted Average Forward Start Days	agnc_WeightedAverageForwardStartDays	2
Debt Securities, Available-for-Sale, Gross Unrealized Gains	agnc_DebtSecuritiesAvailableForSaleGrossUnrealizedGains	$ 1,000,000
Debt Securities, Available-for-Sale, Gross Unrealized Gains	agnc_DebtSecuritiesAvailableForSaleGrossUnrealizedGains	1,000,000
Debt Securities, Available-for-Sale, Gross Unrealized Gains	agnc_DebtSecuritiesAvailableForSaleGrossUnrealizedGains	0
Debt Securities, Available-for-Sale, Gross Unrealized Gains	agnc_DebtSecuritiesAvailableForSaleGrossUnrealizedGains	0
Unrealized gain (loss) on investment securities measured at fair value through net income, net	agnc_Unrealizedgainlossoninvestmentsecuritiesmeasuredatfairvaluethroughnetincomenet	1,183,000,000
Unrealized gain (loss) on investment securities measured at fair value through net income, net	agnc_Unrealizedgainlossoninvestmentsecuritiesmeasuredatfairvaluethroughnetincomenet	(471,000,000)
Gain (loss) on derivative instruments and other securities, net	agnc_Gainlossonderivativeinstrumentsandothersecuritiesnet	(1,019,000,000)
Gain (loss) on derivative instruments and other securities, net	agnc_Gainlossonderivativeinstrumentsandothersecuritiesnet	1,059,000,000
Debt Securities, Available-for-Sale, Gross Unrealized Losses	agnc_DebtSecuritiesAvailableForSaleGrossUnrealizedLosses	499,000,000
Debt Securities, Available-for-Sale, Gross Unrealized Losses	agnc_DebtSecuritiesAvailableForSaleGrossUnrealizedLosses	499,000,000
Debt Securities, Available-for-Sale, Gross Unrealized Losses	agnc_DebtSecuritiesAvailableForSaleGrossUnrealizedLosses	591,000,000
Debt Securities, Available-for-Sale, Gross Unrealized Losses	agnc_DebtSecuritiesAvailableForSaleGrossUnrealizedLosses	591,000,000
Total Agency Securities	agnc_TotalAgencySecurities	70,458,000,000
Total Agency Securities	agnc_TotalAgencySecurities	65,464,000,000
Proceeds from sale of Credit Risk Transfer and non-Agency securities	agnc_ProceedsfromsaleofCreditRiskTransferandnonAgencysecurities	52,000,000
Proceeds from sale of Credit Risk Transfer and non-Agency securities	agnc_ProceedsfromsaleofCreditRiskTransferandnonAgencysecurities	62,000,000
Receivable Under Reverse Repurchase Agreements	agnc_ReceivableUnderReverseRepurchaseAgreements	17,604,000,000
Receivable Under Reverse Repurchase Agreements	agnc_ReceivableUnderReverseRepurchaseAgreements	17,137,000,000
Other Comprehensive Income Reclassification Adjustment For Sale Of Security Reversal Of Prior Period Unrealized Gain And Losses On Realization	agnc_OtherComprehensiveIncomeReclassificationAdjustmentForSaleOfSecurityReversalOfPriorPeriodUnrealizedGainAndLossesOnRealization	0
Other Comprehensive Income Reclassification Adjustment For Sale Of Security Reversal Of Prior Period Unrealized Gain And Losses On Realization	agnc_OtherComprehensiveIncomeReclassificationAdjustmentForSaleOfSecurityReversalOfPriorPeriodUnrealizedGainAndLossesOnRealization	0
Preferred Stock C, Liquidation Preference, Value	agnc_PreferredStockCLiquidationPreferenceValue	325,000,000
Proceeds from Sale of U.S. Treasury securities	agnc_ProceedsFromSaleOfUSTreasurySecurities	7,818,000,000
Proceeds from Sale of U.S. Treasury securities	agnc_ProceedsFromSaleOfUSTreasurySecurities	4,446,000,000
Preferred Stock E, Liquidation Preference, Value	agnc_PreferredStockELiquidationPreferenceValue	403,000,000
Preferred Stock C, Value, Issued	agnc_PreferredStockCValueIssued	315,000,000
Debt Securities, Trading Securities, Gross Unrealized Gains	agnc_DebtSecuritiesTradingSecuritiesGrossUnrealizedGains	376,000,000
Debt Securities, Trading Securities, Gross Unrealized Gains	agnc_DebtSecuritiesTradingSecuritiesGrossUnrealizedGains	0
Debt Securities, Trading Securities, Gross Unrealized Gains	agnc_DebtSecuritiesTradingSecuritiesGrossUnrealizedGains	3,000,000
Debt Securities, Trading Securities, Gross Unrealized Gains	agnc_DebtSecuritiesTradingSecuritiesGrossUnrealizedGains	424,000,000
Debt Securities, Trading Securities, Gross Unrealized Gains	agnc_DebtSecuritiesTradingSecuritiesGrossUnrealizedGains	93,000,000
Debt Securities, Trading Securities, Gross Unrealized Gains	agnc_DebtSecuritiesTradingSecuritiesGrossUnrealizedGains	0
Debt Securities, Trading Securities, Gross Unrealized Gains	agnc_DebtSecuritiesTradingSecuritiesGrossUnrealizedGains	4,000,000
Debt Securities, Trading Securities, Gross Unrealized Gains	agnc_DebtSecuritiesTradingSecuritiesGrossUnrealizedGains	147,000,000
Preferred Stock E, Value, Issued	agnc_PreferredStockEValueIssued	390,000,000
Mortgage Credit Investment Fund Limited Partnership	agnc_MortgageCreditInvestmentFundLimitedPartnership	63,000,000
Mortgage Credit Investment Fund Limited Partnership	agnc_MortgageCreditInvestmentFundLimitedPartnership	64,000,000
Payments To Acquire Non- Agency Mortgage Backed Securities	agnc_PaymentsToAcquireNonAgencyMortgageBackedSecurities	41,000,000
Payments To Acquire Non- Agency Mortgage Backed Securities	agnc_PaymentsToAcquireNonAgencyMortgageBackedSecurities	84,000,000
Preferred Stock G, Value, Issued	agnc_PreferredStockGValueIssued	145,000,000
Principal Payments Received on Available-For-Sale securities	agnc_PrincipalPaymentsReceivedOnAvailableForSaleSecurities	134,000,000
Principal Payments Received on Available-For-Sale securities	agnc_PrincipalPaymentsReceivedOnAvailableForSaleSecurities	143,000,000
Agency securities transferred to consolidated variable interest entities, at fair value	agnc_Agencysecuritiestransferredtoconsolidatedvariableinterestentitiesatfairvalue	95,000,000
Agency securities transferred to consolidated variable interest entities, at fair value	agnc_Agencysecuritiestransferredtoconsolidatedvariableinterestentitiesatfairvalue	97,000,000
Cost Of Sale Of Available For Sale Secuities	agnc_CostOfSaleOfAvailableForSaleSecuities	0
Cost Of Sale Of Available For Sale Secuities	agnc_CostOfSaleOfAvailableForSaleSecuities	0
Cost of Sale of Fair Value Option Securities	agnc_CostofSaleofFairValueOptionSecurities	3,405,000,000
Cost of Sale of Fair Value Option Securities	agnc_CostofSaleofFairValueOptionSecurities	5,218,000,000
Credit Risk Transfer Securities [Member]
Debt Securities, Trading Securities, Unamortized Discount	agnc_DebtSecuritiesTradingSecuritiesUnamortizedDiscount	11,000,000
Debt Securities, Trading Securities, Unamortized Discount	agnc_DebtSecuritiesTradingSecuritiesUnamortizedDiscount	11,000,000
Trading Securities Par	agnc_TradingSecuritiesPar	586,000,000
Trading Securities Par	agnc_TradingSecuritiesPar	576,000,000
Debt Securities, Trading Securities, Unamortized Premium	agnc_DebtSecuritiesTradingSecuritiesUnamortizedPremium	20,000,000
Debt Securities, Trading Securities, Unamortized Premium	agnc_DebtSecuritiesTradingSecuritiesUnamortizedPremium	18,000,000
Debt Securities, Trading Securities, Gross Unrealized Losses	agnc_DebtSecuritiesTradingSecuritiesGrossUnrealizedLosses	0
Debt Securities, Trading Securities, Gross Unrealized Losses	agnc_DebtSecuritiesTradingSecuritiesGrossUnrealizedLosses	0
Debt Securities, Trading Securities, Gross Unrealized Gains	agnc_DebtSecuritiesTradingSecuritiesGrossUnrealizedGains	45,000,000
Debt Securities, Trading Securities, Gross Unrealized Gains	agnc_DebtSecuritiesTradingSecuritiesGrossUnrealizedGains	50,000,000
Greater Than Ten Years [Member]
Derivative, Forward Settlement Value	agnc_DerivativeForwardSettlementValue	2,357,000,000
Derivative, Forward Settlement Value	agnc_DerivativeForwardSettlementValue	2,669,000,000
Greater Than Five Years and Less than or Equal to Seven Years [Member]
Derivative, Forward Settlement Value	agnc_DerivativeForwardSettlementValue	742,000,000
Derivative, Forward Settlement Value	agnc_DerivativeForwardSettlementValue	$ 1,734,000,000
Greater Than One Year and Less Than or Equal to Two Years [Member]
Cash Flow Hedges Derivative Instruments Not Designated As Hedging Instruments Average Months To Expiration	agnc_CashFlowHedgesDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsAverageMonthsToExpiration	8
Options At Cost	agnc_OptionsAtCost	$ 3,000,000
Less Than or Equal to One Year [Member]
Cash Flow Hedges Derivative Instruments Not Designated As Hedging Instruments Average Months To Expiration	agnc_CashFlowHedgesDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsAverageMonthsToExpiration	10
Cash Flow Hedges Derivative Instruments Not Designated As Hedging Instruments Average Months To Expiration	agnc_CashFlowHedgesDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsAverageMonthsToExpiration	5
Cash Flow Hedges Derivative Instruments Not Designated As Hedging Instruments Average Months To Expiration	agnc_CashFlowHedgesDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsAverageMonthsToExpiration	11
Options At Cost	agnc_OptionsAtCost	$ 34,000,000
Options At Cost	agnc_OptionsAtCost	23,000,000
Options At Cost	agnc_OptionsAtCost	3,000,000
Greater Than Seven Years and Less than or Equal to Ten Years [Member]
Derivative, Forward Settlement Value	agnc_DerivativeForwardSettlementValue	169,000,000
Derivative, Forward Settlement Value	agnc_DerivativeForwardSettlementValue	566,000,000
At Cost Basis [Member]
government bonds owned and sold short net	agnc_Governmentbondsownedandsoldshortnet	(1,053,000,000)
government bonds owned and sold short net	agnc_Governmentbondsownedandsoldshortnet	961,000,000
government bonds owned and sold short net	agnc_Governmentbondsownedandsoldshortnet	(657,000,000)
government bonds owned and sold short net	agnc_Governmentbondsownedandsoldshortnet	(2,685,000,000)
government bonds owned and sold short net	agnc_Governmentbondsownedandsoldshortnet	(10,531,000,000)
government bonds owned and sold short net	agnc_Governmentbondsownedandsoldshortnet	(12,329,000,000)
government bonds owned and sold short net	agnc_Governmentbondsownedandsoldshortnet	(1,829,000,000)
government bonds owned and sold short net	agnc_Governmentbondsownedandsoldshortnet	(1,829,000,000)
government bonds owned and sold short net	agnc_Governmentbondsownedandsoldshortnet	(14,070,000,000)
government bonds owned and sold short net	agnc_Governmentbondsownedandsoldshortnet	(15,882,000,000)
30 Year Maturity [Member] \| 6.0% Coupon [Member]
Derivative, Forward Settlement Value	agnc_DerivativeForwardSettlementValue	356,000,000
Derivative, Forward Settlement Value	agnc_DerivativeForwardSettlementValue	2,036,000,000
30 Year Maturity [Member] \| 6.5% Coupon [Member]
Derivative, Forward Settlement Value	agnc_DerivativeForwardSettlementValue	168,000,000
Derivative, Forward Settlement Value	agnc_DerivativeForwardSettlementValue	508,000,000
30 Year Maturity [Member] \| 5.0% Coupon [Member]
Derivative, Forward Settlement Value	agnc_DerivativeForwardSettlementValue	4,417,000,000
Derivative, Forward Settlement Value	agnc_DerivativeForwardSettlementValue	2,703,000,000
30 Year Maturity [Member] \| 3.5% Coupon [Member]
Derivative, Forward Settlement Value	agnc_DerivativeForwardSettlementValue	181,000,000
Derivative, Forward Settlement Value	agnc_DerivativeForwardSettlementValue	2,000,000
30 Year Maturity [Member] \| 5.5% Coupon [Member]
Derivative, Forward Settlement Value	agnc_DerivativeForwardSettlementValue	2,189,000,000
Derivative, Forward Settlement Value	agnc_DerivativeForwardSettlementValue	180,000,000
30 Year Maturity [Member] \| 4.5% Coupon [Member]
Derivative, Forward Settlement Value	agnc_DerivativeForwardSettlementValue	3,549,000,000
Derivative, Forward Settlement Value	agnc_DerivativeForwardSettlementValue	2,210,000,000
30 Year Maturity [Member] \| 3.0% Coupon [Member]
Derivative, Forward Settlement Value	agnc_DerivativeForwardSettlementValue	41,000,000
Derivative, Forward Settlement Value	agnc_DerivativeForwardSettlementValue	504,000,000
30 Year Maturity [Member] \| 4.0% Coupon [Member]
Derivative, Forward Settlement Value	agnc_DerivativeForwardSettlementValue	906,000,000
Derivative, Forward Settlement Value	agnc_DerivativeForwardSettlementValue	$ 112,000,000

Pledged Assets (Assets Pledged as Collateral) (Details) - USD ($) $ in Millions	Mar. 31, 2025	Dec. 31, 2024
Offsetting Assets and Liabilities [Line Items]
Accrued interest on pledged securities	$ 305	$ 280
Total Fair Value of Securities Pledged and Accrued Interest	69,916	1,059
Total Fair Value Of Agency Securities Pledged And Accrued Interest		63,989
Security Owned and Pledged as Collateral, Fair Value	67,750	62,168
Retained Interests in Consolidated VIE's Pledged as Collateral Under Repurchase Agreements	$ 33	$ 33

Pledged Assets (Assets Pledged from Counterparties) (Details) - USD ($) $ in Thousands	Mar. 31, 2025	Dec. 31, 2024
Offsetting Assets and Liabilities [Line Items]
Pledged Financial Instruments, Not Separately Reported, Mortgage-Related Securities Available-for-sale or Held-for-investment	$ (23,000)	$ (55,000)
Obligation to Return Securities Borrowed Under Reverse Repurchase Agreements at Fair Value	4,100,000	3,900,000
Restricted Cash and Securities Pledged	$ 17,517,000	$ 16,968,000

Pledged Assets (Offsetting Assets and Liabilities) (Details) - USD ($) $ in Millions	Mar. 31, 2025	Dec. 31, 2024
Offsetting Assets and Liabilities [Line Items]
Gross Amounts of Recognized Assets	$ 66,169	$ 60,885
Gross Amount Offset in the Consolidated Balance Sheets	0
Net Amounts of Assets Presented in the Consolidated Balance Sheets	66,169	60,885
Financial Instruments	(13,019)	(11,741)
Collateral Received	(53,150)	(49,144)
Net Amount	$ 0	$ 0

Pledged Assets (Securities Pledged as Collateral) (Details) - USD ($) $ in Millions	Mar. 31, 2025	Dec. 31, 2024
Offsetting Assets and Liabilities [Line Items]
Security Owned and Pledged as Collateral, Fair Value	$ 67,750	$ 62,168
Agency Securities Pledged As Collateral Amortized Cost	69,482	64,882
Agency Securities Pledged As Collateral Accrued Interest	$ 296	$ 279

Pledged Assets Repurchase Agreements with Counterparties Greater than or Equal to 5% of Equity at Risk (Details) - days	Mar. 31, 2025	Dec. 31, 2024
Repurchase Agreements with Counterparties Greater than or equal to 5% of Equity at Risk [Line Items]
Weighted Average Days to Maturity	18	11