Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2019	Dec. 31, 2018
American Assets Trust, L.P.
Limited Partners' Capital Account, Units Issued	16,390,548	17,177,608
Limited Partners' Capital Account, Units Outstanding	16,390,548	17,177,608
General Partners' Capital Account, Units Issued	60,068,228	47,335,409
General Partners' Capital Account, Units Outstanding	60,068,228	47,335,409
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	60,068,228	47,335,409
Common stock, shares outstanding	60,068,228	47,335,409