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EQUITY OF AMERICAN ASSETS TRUST, INC. - Narrative (Details) $ in Millions |  | 3 Months Ended | 9 Months Ended
--- | --- | --- | ---
Dec. 03, 2021 USD ($) sales_agent | Sep. 30, 2025 USD ($) shares | Sep. 30, 2024 USD ($) shares | Sep. 30, 2025 USD ($) shares | Sep. 30, 2024 USD ($) shares
Equity [Line Items] |  |  |  |  |
Noncash compensation expense |  | $ 1.8 | $ 2.0 | $ 5.2 | $ 5.3
Unrecognized compensation expense |  | $ 5.4 |  | $ 5.4 |
Operating Partnership Units | American Assets Trust, L.P. |  |  |  |  |
Equity [Line Items] |  |  |  |  |
Weighted average unvested shares outstanding (in shares) | shares |  | 606,062 | 581,314 | 602,093 | 583,247
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 |  | $ 250.0 |

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