SEGMENT REPORTING - Net Real Estate and Secured Note Payable Balances for Each Segment (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Segment Reporting Information [Line Items]
Net Real Estate	$ 2,690,890		$ 2,705,315
Secured Notes Payable	75,000		75,000
Debt issuance costs	1,133		1,295
Capital Expenditures	13,292	$ 25,695
Office
Segment Reporting Information [Line Items]
Net Real Estate	1,608,519		1,614,323
Secured Notes Payable	75,000		75,000
Capital Expenditures	8,986	20,725
Retail
Segment Reporting Information [Line Items]
Net Real Estate	558,801		563,532
Capital Expenditures	2,779	2,525
Multifamily
Segment Reporting Information [Line Items]
Net Real Estate	358,743		361,233
Capital Expenditures	1,200	1,313
Mixed-use
Segment Reporting Information [Line Items]
Net Real Estate	164,827		166,227
Capital Expenditures	327	$ 1,132
American Assets Trust, L.P.
Segment Reporting Information [Line Items]
Net Real Estate	2,690,890		2,705,315
Secured notes payable, net \| American Assets Trust, L.P.
Segment Reporting Information [Line Items]
Debt issuance costs	$ 309		$ 331

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

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