Consolidated Balance Sheets (Parenthetical) - $ / shares	Jun. 30, 2020	Dec. 31, 2019
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 (shares)	60,073,918	60,068,228
Common stock, shares issued (in shares)	60,073,918	60,068,228
American Assets Trust, L.P.
Limited partners' capital, units issued (in shares)	16,390,548	16,390,548
Limited partners' capital, units outstanding (in shares)	16,390,548	16,390,548
General partners' capital, units issued (in shares)	60,073,918	60,068,228
General partners' capital, units outstanding (in shares)	60,073,918	60,068,228