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, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
NUMERATOR
Net income	$ 16,369	$ 12,895	$ 43,471	$ 26,115
Less: Net income attributable to restricted shares	(155)	(145)	(464)	(417)
Less: Income from operations attributable to unitholders in the Operating Partnership	(3,442)	(2,709)	(9,130)	(5,459)
Net income attributable to American Assets Trust, Inc. stockholders	12,772	10,041	33,877	20,239
Income from operations attributable to American Assets Trust, Inc. common stockholders—basic	12,772	10,041	33,877	20,239
Plus: Income from operations attributable to unitholders in the Operating Partnership	3,442	2,709	9,130	5,459
Net income attributable to common stockholders—diluted	$ 16,214	$ 12,750	$ 43,007	$ 25,698
DENOMINATOR
Weighted average shares of common stock outstanding-basic (in shares)	60,044,117	59,990,343	60,041,034	59,986,844
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)	76,225,654	76,171,880	76,222,571	76,168,381
Earnings per common share, basic (in USD per share)	$ 0.21	$ 0.17	$ 0.56	$ 0.34
Earnings per common share, diluted (in USD per share)	$ 0.21	$ 0.17	$ 0.56	$ 0.34