SEGMENT REPORTING - Net Real Estate and Secured Note Payable Balances (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Segment Reporting Information [Line Items]
Real estate, net	$ 2,729,911	$ 2,734,556
Secured Notes Payable	75,000	75,000
Debt issuance costs	1,782	0
American Assets Trust, L.P.
Segment Reporting Information [Line Items]
Real estate, net	2,729,911	2,734,556
Secured notes payable, net \| American Assets Trust, L.P.
Segment Reporting Information [Line Items]
Debt issuance costs	399	422
Office
Segment Reporting Information [Line Items]
Real estate, net	1,617,945	1,615,479
Secured Notes Payable	75,000	75,000
Retail
Segment Reporting Information [Line Items]
Real estate, net	575,148	579,219
Multifamily
Segment Reporting Information [Line Items]
Real estate, net	368,334	370,993
Mixed-use
Segment Reporting Information [Line Items]
Real estate, net	$ 168,484	$ 168,865

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

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
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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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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.

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