v3.5.0.2
Document and Entity Information - shares
9 Months Ended
Sep. 30, 2016
Oct. 31, 2016
Document and Entity Information [Abstract]    
Document Type 10-Q  
Amendment Flag false  
Document Period End Date Sep. 30, 2016  
Document Fiscal Year Focus 2016  
Document Fiscal Period Focus Q3  
Entity Registrant Name AGNC Investment Corp.  
Entity Central Index Key 0001423689  
Entity Filer Category Large Accelerated Filer  
Current Fiscal Year End Date --12-31  
Entity Common Stock, Shares Outstanding   331,046,077
Trading Symbol AGNC