v3.19.3
Document and Entity Information - shares
9 Months Ended
Sep. 30, 2019
Oct. 31, 2019
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-Q  
Amendment Flag false  
Document Period End Date Sep. 30, 2019  
Entity File Number 001-34057  
Document Fiscal Year Focus 2019  
Document Fiscal Period Focus Q3  
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   540,917,953
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Entity Shell Company false  
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 7.750% Series B Cumulative Redeemable Preferred Stock [Member]    
Entity Information [Line Items]    
Title of 12(b) Security Depositary shares of 7.750% Series B Cumulative Redeemable Preferred Stock  
Trading Symbol AGNCB  
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