Derivative, Forward Settlement Value

No definition available.

Name:	agnc_DerivativeForwardSettlementValue
Namespace Prefix:	agnc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Fair value, before effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets elected not to be offset. Excludes assets not subject to a master netting arrangement.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 815
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 7A
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480434/815-10-50-7A

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Topic 210
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 22
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483444/210-20-55-22

Reference 3: http://www.xbrl.org/2003/role/exampleRef
-Topic 210
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 21
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483444/210-20-55-21

Reference 4: http://www.xbrl.org/2003/role/exampleRef
-Topic 210
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 20
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483444/210-20-55-20

Reference 5: http://www.xbrl.org/2003/role/exampleRef
-Topic 210
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 15
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483444/210-20-55-15

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 210
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483466/210-20-50-3

Reference 7: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 50
-Paragraph 4D
-Subparagraph (c)(2)
-SubTopic 20
-Topic 860
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481326/860-20-50-4D

+ Details

Name:	us-gaap_DerivativeFairValueOfDerivativeAsset
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Fair value of the assets less the liabilities of a derivative or group of derivatives.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 825
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 10
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482907/825-10-50-10

+ Details

Name:	us-gaap_DerivativeFairValueOfDerivativeNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Fair value as of the balance sheet date of derivative instrument not designated as hedging instrument and classified as a liability.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 815
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 182
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480401/815-10-55-182

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 815
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 4B
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480434/815-10-50-4B

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 815
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 4B
-Subparagraph (c)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480434/815-10-50-4B

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 815
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 4B
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480434/815-10-50-4B

+ Details

Name:	us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsLiabilityAtFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

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.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 815
-SubTopic 20
-Name Accounting Standards Codification
-Section 25
-Paragraph 6A
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480682/815-20-25-6A

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 815
-SubTopic 40
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480237/815-40-50-5

+ Details

Name:	us-gaap_DerivativeLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Nominal or face amount used to calculate payment on derivative.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 815
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 181
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480401/815-10-55-181

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 815
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1B
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480434/815-10-50-1B

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 815
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1A
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480434/815-10-50-1A

+ Details

Name:	us-gaap_DerivativeNotionalAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=agnc_TBAAndForwardSettlingSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=agnc_SOFRFuturesContractsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	agnc_DerivativeByMaturityYearsAxis=agnc_A30YearMaturityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	agnc_DerivativePositionAxis=agnc_A6.5CouponMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	agnc_DerivativePositionAxis=agnc_A5.5CouponMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	agnc_DerivativePositionAxis=agnc_A5.0CouponMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	agnc_DerivativePositionAxis=agnc_A3.0CouponMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	agnc_DerivativePositionAxis=agnc_A3.5CouponMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	agnc_DerivativePositionAxis=agnc_A4.0CouponMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	agnc_DerivativePositionAxis=agnc_A4.5CouponMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	agnc_DerivativePositionAxis=agnc_A60CouponMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PositionAxis=us-gaap_ShortMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Derivative and Other Hedging Instruments (TBA Securities by Coupon and Issuer) (Details) - USD ($) $ in Millions	Mar. 31, 2025	Dec. 31, 2024	Mar. 31, 2024	Dec. 31, 2023
Derivative [Line Items]
Derivative liability, fair value	$ (70)	$ (94)
TBA and Forward Settling Agency Securities [Member]
Derivative [Line Items]
Derivative, Notional Amount	(7,811)	(6,955)	$ (8,651)	$ (5,332)
Cost Basis	(7,429)	(6,887)
Net long TBA position, at fair value	(7,473)	(6,861)
TBA, net carrying value	44	(26)
SOFR Futures Contracts
Derivative [Line Items]
Derivative, Notional Amount	(1,200)	(1,200)
Derivative liability, fair value	0	(7)
30 Year Maturity [Member] \| 6.5% Coupon \| TBA and Forward Settling Agency Securities [Member]
Derivative [Line Items]
Derivative, Notional Amount	(164)	(499)
Cost Basis	(168)	(508)
Net long TBA position, at fair value	(168)	(509)
TBA, net carrying value	0	1
30 Year Maturity [Member] \| 5.5% Coupon \| TBA and Forward Settling Agency Securities [Member]
Derivative [Line Items]
TBA, net carrying value	11	(30)
30 Year Maturity [Member] \| 5.0% Coupon \| TBA and Forward Settling Agency Securities [Member]
Derivative [Line Items]
Derivative, Notional Amount	(4,517)	(2,780)
Cost Basis	(4,417)	(2,703)
Net long TBA position, at fair value	(4,421)	(2,700)
TBA, net carrying value	4	(3)
30 Year Maturity [Member] \| 3.0% Coupon [Member] \| TBA and Forward Settling Agency Securities [Member]
Derivative [Line Items]
Derivative, Notional Amount	(50)
Cost Basis	(41)
Net long TBA position, at fair value	(38)
TBA, net carrying value	(3)	7
30 Year Maturity [Member] \| 3.5% Coupon [Member] \| TBA and Forward Settling Agency Securities [Member]
Derivative [Line Items]
Derivative, Notional Amount	(200)	0
Cost Basis	(181)	(2)
Net long TBA position, at fair value	(180)	0
TBA, net carrying value	(1)	(2)
30 Year Maturity [Member] \| 4.0% Coupon [Member] \| TBA and Forward Settling Agency Securities [Member]
Derivative [Line Items]
Derivative, Notional Amount	(972)	(122)
Cost Basis	(906)	(112)
Net long TBA position, at fair value	(904)	(111)
TBA, net carrying value	(2)	(1)
30 Year Maturity [Member] \| 4.5% Coupon [Member] \| TBA and Forward Settling Agency Securities [Member]
Derivative [Line Items]
Derivative, Notional Amount	(3,736)	(2,342)
Cost Basis	(3,549)	(2,210)
Net long TBA position, at fair value	(3,570)	(2,204)
TBA, net carrying value	21	(6)
30 Year Maturity [Member] \| 6.0% Coupon \| TBA and Forward Settling Agency Securities [Member]
Derivative [Line Items]
Derivative, Notional Amount	(365)	(2,033)
Cost Basis	(356)	(2,036)
Net long TBA position, at fair value	(370)	(2,044)
TBA, net carrying value	14	8
30 Year Maturity [Member] \| Short [Member] \| 5.5% Coupon \| TBA and Forward Settling Agency Securities [Member]
Derivative [Line Items]
Derivative, Notional Amount	(2,193)	(235)
Cost Basis	(2,189)	(180)
Net long TBA position, at fair value	$ (2,178)	(210)
30 Year Maturity [Member] \| Short [Member] \| 3.0% Coupon [Member] \| TBA and Forward Settling Agency Securities [Member]
Derivative [Line Items]
Derivative, Notional Amount		(586)
Cost Basis		(504)
Net long TBA position, at fair value		$ (497)