v3.5.0.2
Document and Entity Information - shares
6 Months Ended
Jun. 30, 2016
Jul. 29, 2016
Document Information [Line Items]    
Document Type 10-Q  
Amendment Flag false  
Document Period End Date Jun. 30, 2016  
Document Fiscal Year Focus 2016  
Document Fiscal Period Focus Q2  
Trading Symbol AAT  
Entity Registrant Name AMERICAN ASSETS TRUST, INC.  
Entity Central Index Key 0001500217  
Current Fiscal Year End Date --12-31  
Entity Filer Category Large Accelerated Filer  
Entity Common Stock, Shares Outstanding   45,410,806
American Assets Trust, L.P.    
Document Information [Line Items]    
Document Type 10-Q  
Amendment Flag false  
Document Period End Date Jun. 30, 2016  
Document Fiscal Year Focus 2016  
Document Fiscal Period Focus Q2  
Entity Registrant Name AMERICAN ASSETS TRUST, L.P.  
Entity Central Index Key 0001509570  
Current Fiscal Year End Date --12-31  
Entity Filer Category Non-accelerated Filer