Consolidated Balance Sheets (Unaudited) (Parenthetical) - $ / shares	Sep. 30, 2016	Dec. 31, 2015
Common Shares
Common stock, par value (in USD per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	490,000,000	490,000,000
Common stock, shares outstanding (in shares)	45,640,980	45,407,719
Common stock, shares issued (in shares)	45,640,980	45,407,719
American Assets Trust, L.P.
Limited partners' capital, units issued (in shares)	17,888,822	17,899,516
Limited partners' capital, units outstanding (in shares)	17,888,822	17,899,516
General partners' capital, units issued (in shares)	45,640,980	45,407,719
General partners' capital, units outstanding (in shares)	45,640,980	45,407,719