v2.4.0.8
Document and Entity Information
3 Months Ended
Mar. 31, 2015
Apr. 30, 2015
Document and Entity Information [Abstract]    
Document Type 10-Q  
Amendment Flag false  
Document Period End Date Mar. 31, 2015  
Document Fiscal Year Focus 2015  
Document Fiscal Period Focus Q1  
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