Consolidated Balance Sheets (Unaudited) (Parenthetical) - $ / shares	Sep. 30, 2015	Dec. 31, 2014
Common Shares
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	490,000,000	490,000,000
Common stock, shares outstanding	45,349,121	43,701,669
Common stock, shares issued	45,349,121	43,701,669
American Assets Trust, L.P.
Limited Partners' Capital Account, Units Issued	17,899,516	17,905,257
Limited Partners' Capital Account, Units Outstanding	17,899,516	17,905,257
General Partners' Capital Account, Units Issued	45,349,121	43,701,669
General Partners' Capital Account, Units Outstanding	45,349,121	43,701,669