Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2017	Dec. 31, 2016
American Assets Trust, L.P.
Limited Partners' Capital Account, Units Issued	17,194,980	17,888,822
Limited Partners' Capital Account, Units Outstanding	17,194,980	17,888,822
General Partners' Capital Account, Units Issued	47,204,588	45,732,109
General Partners' Capital Account, Units Outstanding	47,204,588	45,732,109
Common Stock
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	490,000,000	490,000,000
Common stock, shares issued	47,204,588	45,732,109
Common stock, shares outstanding	47,204,588	45,732,109