SEGMENT REPORTING - Net Real Estate and Secured Note Payable Balances for Each Segment (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2023	Dec. 31, 2022
Segment Reporting Information [Line Items]
Net real estate	$ 2,705,315	$ 2,734,556
Secured Notes Payable	75,000	75,000
Capital Expenditures	89,887	121,155
Office
Segment Reporting Information [Line Items]
Net real estate	1,614,323	1,615,479
Secured Notes Payable	75,000	75,000
Capital Expenditures	71,336	102,443
Retail
Segment Reporting Information [Line Items]
Net real estate	563,532	579,219
Secured Notes Payable	0	0
Capital Expenditures	8,856	12,177
Multifamily
Segment Reporting Information [Line Items]
Net real estate	361,233	370,993
Capital Expenditures	5,902	4,889
Mixed-Use
Segment Reporting Information [Line Items]
Net real estate	166,227	168,865
Capital Expenditures	3,793	1,646
American Assets Trust, L.P.
Segment Reporting Information [Line Items]
Net real estate	2,705,315	2,734,556
Secured notes payable \| American Assets Trust, L.P.
Segment Reporting Information [Line Items]
Debt issuance costs	$ 331	$ 422

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Amount, after accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
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Including the current and noncurrent portions, aggregate carrying amount of all types of notes payable, as of the balance sheet date, with initial maturities beyond one year or beyond the normal operating cycle, if longer.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
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- Definition

Amount of real estate investment property, net of accumulated depreciation, which may include the following: (1) land available-for-sale; (2) land available-for-development; (3) investments in building and building improvements; (4) tenant allowances; (5) developments in-process; (6) rental properties; and (7) other real estate investments.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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-SubTopic 210
-Name Accounting Standards Codification
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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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