Derivative, Forward Settlement Value

No definition available.

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

- Definition

government bonds owned and sold short net

+ References

No definition available.

+ Details

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

- Definition

WeightedAverageYieldPercentage

+ References

No definition available.

+ Details

Name:	agnc_WeightedAverageYieldPercentage
Namespace Prefix:	agnc_
Data Type:	dtr-types:percentItemType
Balance Type:	na
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

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

Derivative and Other Hedging Instruments (US Treasury Securities) (Details) - USD ($) $ in Millions	Mar. 31, 2025	Dec. 31, 2024	Mar. 31, 2024	Dec. 31, 2023
Derivative [Line Items]
U.S. Treasury securities, net	$ (13,900)	$ (15,101)
At Par Value [Member]
Derivative [Line Items]
U.S. Treasury securities, net	(14,420)	(16,207)
US Treasury Securities [Member]
Derivative [Line Items]
Derivative, Fair Value, Net	(38)	83
TBA and Forward Settling Agency Securities [Member]
Derivative [Line Items]
Derivative, Notional Amount	7,811	6,955	$ 8,651	$ 5,332
Derivative, Forward Settlement Value	7,429	6,887
Derivative Asset, Fair Value, Gross Asset	7,473	6,861
Derivative, Fair Value, Net	44	(26)
Less Than or Equal to Five Years
Derivative [Line Items]
U.S. Treasury securities, net	(1,056)	956
Greater Than Five Years and Less than or Equal to Seven Years [Member]
Derivative [Line Items]
U.S. Treasury securities, net	(671)	(2,722)
Greater Than Seven Years and Less than or Equal to Ten Years [Member]
Derivative [Line Items]
U.S. Treasury securities, net	(10,910)	(12,659)
Greater Than Ten Years [Member]
Derivative [Line Items]
U.S. Treasury securities, net	(1,783)	(1,782)
Greater Than Ten Years [Member] \| US Treasury Securities [Member]
Derivative [Line Items]
Derivative, Fair Value, Net	(37)	61
Greater Than Five Years and Less than or Equal to Seven Years [Member] \| US Treasury Securities [Member]
Derivative [Line Items]
Derivative, Notional Amount	668
Derivative, Forward Settlement Value	742
Derivative Asset, Fair Value, Gross Asset	743
Derivative, Fair Value, Net	1	13
Greater Than Seven Years and Less than or Equal to Ten Years [Member] \| US Treasury Securities [Member]
Derivative [Line Items]
Derivative, Fair Value, Net	$ (2)	$ 9
Short [Member] \| US Treasury Securities [Member]
Derivative [Line Items]
Weighted Average Yield Percentage	4.06%	3.85%
Short [Member] \| US Treasury Securities [Member]
Derivative [Line Items]
Derivative, Notional Amount	$ 17,636	$ 17,792	12,807	11,347
Derivative, Forward Settlement Value	1,784	4,969
Derivative Asset, Fair Value, Gross Asset	1,822	4,886
Short [Member] \| US Treasury Securities [Member] \| Future [Member]
Derivative [Line Items]
Derivative, Notional Amount	1,523	4,373	$ 3,039	$ 6,429
Short [Member] \| Greater Than Ten Years [Member] \| US Treasury Securities [Member]
Derivative [Line Items]
Derivative, Notional Amount	2,041	2,291
Derivative, Forward Settlement Value	2,357	2,669
Derivative Asset, Fair Value, Gross Asset	2,394	2,608
Short [Member] \| Greater Than Five Years and Less than or Equal to Seven Years [Member] \| US Treasury Securities [Member]
Derivative [Line Items]
Derivative, Notional Amount		1,582
Derivative, Forward Settlement Value		1,734
Derivative Asset, Fair Value, Gross Asset		1,721
Short [Member] \| Greater Than Seven Years and Less than or Equal to Ten Years [Member] \| US Treasury Securities [Member]
Derivative [Line Items]
Derivative, Notional Amount	150	500
Derivative, Forward Settlement Value	169	566
Derivative Asset, Fair Value, Gross Asset	$ 171	$ 557
Long [Member] \| US Treasury Securities [Member]
Derivative [Line Items]
Weighted Average Yield Percentage	4.42%	4.27%
Fair Value Hedging [Member]
Derivative [Line Items]
U.S. Treasury securities, net	$ (13,900)	$ (15,101)
Fair Value Hedging [Member] \| Less Than or Equal to Five Years
Derivative [Line Items]
U.S. Treasury securities, net	(1,058)	956
Fair Value Hedging [Member] \| Greater Than Five Years and Less than or Equal to Seven Years [Member]
Derivative [Line Items]
U.S. Treasury securities, net	(507)	(2,302)
Fair Value Hedging [Member] \| Greater Than Seven Years and Less than or Equal to Ten Years [Member]
Derivative [Line Items]
U.S. Treasury securities, net	(10,526)	(11,999)
Fair Value Hedging [Member] \| Greater Than Ten Years [Member]
Derivative [Line Items]
U.S. Treasury securities, net	(1,809)	(1,756)
Fair Value Hedging [Member] \| Long [Member]
Derivative [Line Items]
U.S. Treasury securities, net	3,300	1,600
At Cost Basis [Member]
Derivative [Line Items]
U.S. Treasury securities, net	(14,070)	(15,882)
At Cost Basis [Member] \| Less Than or Equal to Five Years
Derivative [Line Items]
U.S. Treasury securities, net	(1,053)	961
At Cost Basis [Member] \| Greater Than Five Years and Less than or Equal to Seven Years [Member]
Derivative [Line Items]
U.S. Treasury securities, net	(657)	(2,685)
At Cost Basis [Member] \| Greater Than Seven Years and Less than or Equal to Ten Years [Member]
Derivative [Line Items]
U.S. Treasury securities, net	(10,531)	(12,329)
At Cost Basis [Member] \| Greater Than Ten Years [Member]
Derivative [Line Items]
U.S. Treasury securities, net	$ (1,829)	$ (1,829)