EQUITY OF AMERICAN ASSETS TRUST, INC. - Narrative (Details) $ in Millions		3 Months Ended
	Dec. 03, 2021 USD ($) sales_agent	Mar. 31, 2024 USD ($) shares	Mar. 31, 2023 USD ($) shares
Equity [Line Items]
Noncash compensation expense		$ 1.6	$ 2.0
Unrecognized compensation expense		$ 7.1
Operating Partnership Units | American Assets Trust, L.P.
Equity [Line Items]
Weighted average unvested shares outstanding (in shares) | shares		585,210	573,253
At The Market Equity Program
Equity [Line Items]
Number of sales agents | sales_agent	5
Aggregate offering price of common share	$ 250.0
Common shares issued (in shares) | shares		0
Remaining capacity available for issuance		$ 250.0