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SEGMENT REPORTING - Summary of Net Real Estate and Secured Note Payable Balances by Segments (Details) - USD ($) $ in Thousands | 3 Months Ended | 9 Months Ended |
--- | --- | --- | ---
Sep. 30, 2025 | Sep. 30, 2024 | Sep. 30, 2025 | Sep. 30, 2024 | Dec. 31, 2024
Segment Reporting Information [Line Items] |  |  |  |  |
Net Real Estate | $ 2,626,930 |  | $ 2,626,930 |  | $ 2,587,486
Secured Notes Payable | 75,000 |  | 75,000 |  | 75,000
Debt issuance costs | 162 |  | 162 |  | 648
Capital Expenditures | 19,233 | $ 26,339 | 59,519 | $ 56,763 |
American Assets Trust, L.P. |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |
Net Real Estate | 2,626,930 |  | 2,626,930 |  | 2,587,486
Secured notes payable, net | American Assets Trust, L.P. |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |
Debt issuance costs | 173 |  | 173 |  | 241
Office |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |
Net Real Estate | 1,588,085 |  | 1,588,085 |  | 1,597,458
Secured Notes Payable | 75,000 |  | 75,000 |  | 75,000
Capital Expenditures | 13,185 | 20,261 | 47,354 | 41,930 |
Retail |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |
Net Real Estate | 472,969 |  | 472,969 |  | 478,037
Capital Expenditures | 4,500 | 4,267 | 7,146 | 9,651 |
Multifamily |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |
Net Real Estate | 408,395 |  | 408,395 |  | 351,016
Capital Expenditures | 1,110 | 1,582 | 3,072 | 4,260 |
Mixed-Use |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |
Net Real Estate | 157,481 |  | 157,481 |  | $ 160,975
Capital Expenditures | $ 438 | $ 229 | $ 1,947 | $ 922 |

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- Definition 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://www.xbrl.org/2009/role/commonPracticeRef -Topic 835 -SubTopic 30 -Name Accounting Standards Codification -Section 45 -Paragraph 1A -Publisher FASB -URI https://asc.fasb.org/1943274/2147482925/835-30-45-1A Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 835 -SubTopic 30 -Name Accounting Standards Codification -Section 45 -Paragraph 2 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482925/835-30-45-2 Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 835 -SubTopic 30 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482900/835-30-50-1 Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 470 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1D -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481139/470-20-50-1D + Details
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