Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2021	Dec. 31, 2020
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	60,525,580	60,476,292
Common stock, shares outstanding	60,525,580	60,476,292
American Assets Trust, L.P.
Limited Partners' Capital Account, Units Issued	16,181,537	16,181,537
Limited Partners' Capital Account, Units Outstanding	16,181,537	16,181,537
General Partners' Capital Account, Units Issued	60,525,580	60,476,292
General Partners' Capital Account, Units Outstanding	60,525,580	60,476,292