Document and Entity Information - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Feb. 09, 2023	Jun. 30, 2022
Entity Information [Line Items]
Entity Incorporation, State or Country Code	DE
Document Transition Report	false
Document Quarterly Report	true
Entity Tax Identification Number	26-1701984
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2022
Entity File Number	001-34057
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	FY
Entity Registrant Name	AGNC INVESTMENT CORP.
Entity Address, Address Line One	2 Bethesda Metro Center, 12th Floor
Entity Address, City or Town	Bethesda
Entity Address, State or Province	MD
Entity Address, Postal Zip Code	20814
City Area Code	301
Local Phone Number	968-9315
Entity Central Index Key	0001423689
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Current Fiscal Year End Date	--12-31
Entity Common Stock, Shares Outstanding		574,656,885
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Shell Company	false
ICFR Auditor Attestation Flag	true
Auditor Firm ID	42
Auditor Name	Ernst & Young LLP
Auditor Location	Tysons, Virginia
Entity Public Float			$ 4,800,000
Common Stock [Member]
Entity Information [Line Items]
Title of 12(b) Security	Common Stock, par value $0.01 per share
Trading Symbol	AGNC
Security Exchange Name	NASDAQ
Depository shares each representing a 1/1,000th interest in a share of 7.000% Series C Fixed-to-Floating Rate Cumulative Redeemable Preferred Stock [Member]
Entity Information [Line Items]
Title of 12(b) Security	Depositary shares of 7.000% Series C Fixed-to-Floating Rate Cumulative Redeemable Preferred Stock
Trading Symbol	AGNCN
Security Exchange Name	NASDAQ
Depository shares each representing a 1/1,000th interest in a share of 6.875% Series D Fixed-to-Floating Rate Cumulative Redeemable Preferred Stock [Member]
Entity Information [Line Items]
Title of 12(b) Security	Depositary shares of 6.875% Series D Fixed-to-Floating Rate Cumulative Redeemable Preferred Stock
Trading Symbol	AGNCM
Security Exchange Name	NASDAQ
Depository shares each representing a 1/1000th interest in a share of 6.500% Series E Fixed-to-Floating Rate Cumulative Redeemable Preferred Stock [Member]
Entity Information [Line Items]
Title of 12(b) Security	Depositary shares of 6.50% Series E Fixed-to-Floating Rate Cumulative Redeemable Preferred Stock
Trading Symbol	AGNCO
Security Exchange Name	NASDAQ
Depositary shares each representing a 1/1000th interest in a share of 6.125% Series F Fixed-to-Floating Rate Cumulative Redeemable Preferred Stock [Member]
Entity Information [Line Items]
Title of 12(b) Security	Depositary shares of 6.125% Series F Fixed-to-Floating Rate Cumulative Redeemable Preferred Stock
Trading Symbol	AGNCP
Security Exchange Name	NASDAQ
Depositary shares each representing a 1/1000th interest in a share of 7.75% Series G Fixed Rate Reset Cumulative Redeemable Preferred Stock
Entity Information [Line Items]
Title of 12(b) Security	Depositary shares of 7.75% Series G Fixed-Rate Reset Cumulative Redeemable Preferred Stock
Trading Symbol	AGNCL
Security Exchange Name	NASDAQ