EQUITY OF AMERICAN ASSETS TRUST, INC. - Computation of Basic and Diluted EPS (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
NUMERATOR
Net income	$ 15,135	$ 16,369	$ 51,198	$ 43,471
Less: Net income attributable to restricted shares	(189)	(155)	(568)	(464)
Less: Income from operations attributable to unitholders in the Operating Partnership	(3,168)	(3,442)	(10,733)	(9,130)
NET INCOME ATTRIBUTABLE TO AMERICAN ASSETS TRUST	11,778	12,772	39,897	33,877
Income from operations attributable to American Assets Trust, Inc. common stockholders—basic	11,778	12,772	39,897	33,877
Plus: Income from operations attributable to unitholders in the Operating Partnership	3,168	3,442	10,733	9,130
Net income attributable to common stockholders—diluted	$ 14,946	$ 16,214	$ 50,630	$ 43,007
DENOMINATOR
Weighted average common shares outstanding—basic (in shares)	60,150,681	60,044,117	60,147,189	60,041,034
Effect of dilutive securities-conversion of Operating Partnership units (in shares)	16,181,537	16,181,537	16,181,537	16,181,537
Weighted average common shares outstanding - diluted (in shares)	76,332,218	76,225,654	76,328,726	76,222,571
Earnings per common share, basic (in USD per share)	$ 0.20	$ 0.21	$ 0.66	$ 0.56
Earnings per common share, diluted (in USD per share)	$ 0.20	$ 0.21	$ 0.66	$ 0.56