EQUITY OF AMERICAN ASSETS TRUST, INC. - Computation of Basic and Diluted EPS (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
NUMERATOR
Net income	$ 13,514	$ 1,733
Less: Net income attributable to restricted shares	(155)	(137)
Less: Income from operations attributable to unitholders in the Operating Partnership	(2,836)	(339)
Net income attributable to American Assets Trust, Inc. stockholders	10,523	1,257
Income from operations attributable to American Assets Trust, Inc. common stockholders—basic	10,523	1,257
Plus: Income from operations attributable to unitholders in the Operating Partnership	2,836	339
Net income attributable to common stockholders—diluted	$ 13,359	$ 1,596
DENOMINATOR
Weighted average common shares outstanding-basic (in shares)	60,038,683	59,984,335
Effect of dilutive securities-conversion of Operating Partnership units (in shares)	16,181,537	16,181,537
Weighted average common shares outstanding - diluted (in shares)	76,220,220	76,165,872
Earnings (loss) per common share - basic
Earnings per common share, basic (in USD per share)	$ 0.18	$ 0.02
Earnings (loss) per common share - diluted
Earnings per common share, diluted (in USD per share)	$ 0.18	$ 0.02