v2.4.0.8
Document and Entity Information
9 Months Ended
Sep. 30, 2014
Oct. 31, 2014
Document and Entity Information [Abstract]    
Document Type 10-Q  
Amendment Flag false  
Document Period End Date Sep. 30, 2014  
Document Fiscal Year Focus 2014  
Document Fiscal Period Focus Q3  
Entity Registrant Name American Capital Agency Corp  
Entity Central Index Key 0001423689  
Entity Filer Category Large Accelerated Filer  
Current Fiscal Year End Date --12-31  
Entity Common Stock, Shares Outstanding   352,788,707
Trading Symbol AGNC  
Entity Well-known Seasoned Issuer Yes  
Entity Voluntary Filers No  
Entity Current Reporting Status Yes