DEBT - Narrative (Details)						6 Months Ended
	Jul. 18, 2024 USD ($)	Jan. 05, 2023 USD ($) extension	Jan. 05, 2022 USD ($) extension	Jan. 26, 2021 USD ($)	Oct. 31, 2014 USD ($)	Jun. 30, 2024 USD ($)	Jun. 30, 2023 USD ($)	Jan. 05, 2024	Jul. 30, 2019 USD ($)	Jul. 19, 2017 USD ($)	May 23, 2017 USD ($)	Mar. 01, 2017 USD ($)
Debt Instrument [Line Items]
Repayments of unsecured debt						$ 0	$ 150,000,000
Repayment of unsecured line of credit						0	36,000,000
American Assets Trust, L.P.
Debt Instrument [Line Items]
Repayments of unsecured debt						0	150,000,000
Repayment of unsecured line of credit						$ 0	$ 36,000,000
Unsecured term loans, net | American Assets Trust, L.P. | Secured Overnight Financing Rate
Debt Instrument [Line Items]
Basis spread on variable rate		1.00%
Unsecured term loans, net | American Assets Trust, L.P. | Federal Funds Rate
Debt Instrument [Line Items]
Basis spread on variable rate		0.50%
Unsecured term loans, net | American Assets Trust, L.P. | Base Rate
Debt Instrument [Line Items]
Basis spread on variable rate		0.00%
Unsecured term loans, net | American Assets Trust, L.P. | Minimum | Secured Overnight Financing Rate
Debt Instrument [Line Items]
Basis spread on variable rate		1.20%
Unsecured term loans, net | American Assets Trust, L.P. | Maximum | Secured Overnight Financing Rate
Debt Instrument [Line Items]
Basis spread on variable rate		1.90%
3.375% Senior Notes | Unsecured term loans, net | American Assets Trust, L.P.
Debt Instrument [Line Items]
Stated Interest Rate				3.375%		3.375%
Face amount of debt				$ 500,000,000
Note offering percent				0.98935
Weighted average yield of investment				3.502%
Proceeds from debt, net of issuance costs				$ 489,700,000
Maximum aggregate debt ratio				60.00%
Minimum debt service ratio				1.5
Maximum secured debt ratio				40.00%
Minimum maintenance of total unencumbered assets				150.00%
Senior Guaranteed Notes, Series A | Unsecured term loans, net | American Assets Trust, L.P.
Debt Instrument [Line Items]
Repayments of unsecured debt				$ 150,000,000
Make-whole payment				3,900,000
Second Amended and Restated Credit Facility | Unsecured term loans, net | American Assets Trust, L.P.
Debt Instrument [Line Items]
Repayment of unsecured line of credit				$ 100,000,000
Note Purchase Agreement | Senior Guaranteed Notes | American Assets Trust, L.P.
Debt Instrument [Line Items]
Face amount of debt					$ 350,000,000
Partial debt repayment, minimum percentage of principal					5.00%
Full debt repayment percentage of principal plus a make-whole amount					100.00%
Note Purchase Agreement | Senior Guaranteed Notes, Series A | American Assets Trust, L.P.
Debt Instrument [Line Items]
Stated Interest Rate					4.04%
Face amount of debt					$ 150,000,000
Note Purchase Agreement | Senior Guaranteed Notes, Series B | American Assets Trust, L.P.
Debt Instrument [Line Items]
Stated Interest Rate					4.45%
Face amount of debt					$ 100,000,000
Note Purchase Agreement | Senior Guaranteed Notes, Series C | American Assets Trust, L.P.
Debt Instrument [Line Items]
Stated Interest Rate					4.50%
Face amount of debt					$ 100,000,000
Senior Guaranteed Notes, Series D | Unsecured term loans, net | American Assets Trust, L.P.
Debt Instrument [Line Items]
Stated Interest Rate						4.29%						4.29%
Face amount of debt												$ 250,000,000
Senior Guaranteed Notes, Series E | Unsecured term loans, net | American Assets Trust, L.P.
Debt Instrument [Line Items]
Stated Interest Rate						4.24%					4.24%
Face amount of debt											$ 100,000,000
Senior Guaranteed Notes, Series F | Unsecured term loans, net | Subsequent Event
Debt Instrument [Line Items]
Borrowings	$ 100,000,000
Senior Guaranteed Notes, Series F | Unsecured term loans, net | American Assets Trust, L.P.
Debt Instrument [Line Items]
Stated Interest Rate						3.78%				3.78%
Face amount of debt										$ 100,000,000
Senior Guaranteed Notes, Series F | Unsecured term loans, net | American Assets Trust, L.P. | Subsequent Event
Debt Instrument [Line Items]
Borrowings	$ 100,000,000
Senior Guaranteed Notes, Series G | Unsecured term loans, net | American Assets Trust, L.P.
Debt Instrument [Line Items]
Stated Interest Rate						3.91%			3.91%
Face amount of debt									$ 150,000,000
Third Amended and Restated Credit Facility | American Assets Trust, L.P.
Debt Instrument [Line Items]
Revolving credit facility borrowing limit, maximum borrowing capacity			$ 500,000,000
Third Amended and Restated Credit Facility | American Assets Trust, L.P. | Base Rate
Debt Instrument [Line Items]
Basis spread on variable rate			1.00%
Third Amended and Restated Credit Facility | Unsecured term loans, net | American Assets Trust, L.P.
Debt Instrument [Line Items]
Revolving credit facility borrowing limit, maximum borrowing capacity			$ 100,000,000
Number of extensions available | extension			2
Extension term			6 months
Third Amended and Restated Credit Facility | Unsecured term loans, net | American Assets Trust, L.P. | Secured Overnight Financing Rate
Debt Instrument [Line Items]
Basis spread on variable rate			1.00%
Third Amended and Restated Credit Facility | Unsecured term loans, net | American Assets Trust, L.P. | Federal Funds Rate
Debt Instrument [Line Items]
Basis spread on variable rate			0.50%
Third Amended and Restated Credit Facility | Unsecured term loans, net | American Assets Trust, L.P. | Minimum | Secured Overnight Financing Rate
Debt Instrument [Line Items]
Basis spread on variable rate			1.20%
Third Amended and Restated Credit Facility | Unsecured term loans, net | American Assets Trust, L.P. | Minimum | Base Rate
Debt Instrument [Line Items]
Basis spread on variable rate			0.20%
Third Amended and Restated Credit Facility | Unsecured term loans, net | American Assets Trust, L.P. | Maximum | Secured Overnight Financing Rate
Debt Instrument [Line Items]
Basis spread on variable rate			1.70%
Third Amended and Restated Credit Facility | Unsecured term loans, net | American Assets Trust, L.P. | Maximum | Base Rate
Debt Instrument [Line Items]
Basis spread on variable rate			0.70%
Third Amended and Restated Credit Facility | Unsecured line of credit, net
Debt Instrument [Line Items]
Maximum leverage ratio of revolving credit facility			60.00%
Maximum secured leverage ratio on revolving credit facility			40.00%
Minimum fixed charge coverage ratio covenant threshold			1.50
Minimum interest coverage ratio covenant threshold			1.75
Maximum unsecured leverage ratio (in percentage)			60.00%
Maximum recourse indebtedness of total asset value			15.00%
Percentage annual distributions cannot exceed funds from operations			95.00%
Third Amended and Restated Credit Facility | Unsecured line of credit, net | American Assets Trust, L.P.
Debt Instrument [Line Items]
Debt issuance costs, net, revolving credit facility						$ 970,000
Weighted average interest rate						6.53%
Third Amended and Restated Credit Facility | Unsecured line of credit, net | American Assets Trust, L.P. | Revolving Credit Facility
Debt Instrument [Line Items]
Revolving credit facility borrowing limit, maximum borrowing capacity			$ 400,000,000
Third Amended and Restated Credit Facility | Unsecured line of credit, net | American Assets Trust, L.P. | Revolving Credit Facility | Minimum | Secured Overnight Financing Rate
Debt Instrument [Line Items]
Basis spread on variable rate			1.05%
Third Amended and Restated Credit Facility | Unsecured line of credit, net | American Assets Trust, L.P. | Revolving Credit Facility | Minimum | Base Rate
Debt Instrument [Line Items]
Basis spread on variable rate			0.10%
Third Amended and Restated Credit Facility | Unsecured line of credit, net | American Assets Trust, L.P. | Revolving Credit Facility | Maximum | Secured Overnight Financing Rate
Debt Instrument [Line Items]
Basis spread on variable rate			1.50%
Third Amended and Restated Credit Facility | Unsecured line of credit, net | American Assets Trust, L.P. | Revolving Credit Facility | Maximum | Base Rate
Debt Instrument [Line Items]
Basis spread on variable rate			0.50%
Term Loan A | American Assets Trust, L.P. | Interest Rate Swap
Debt Instrument [Line Items]
Fixed interest rate on derivative						2.70%		2.70%
Term Loan B | American Assets Trust, L.P.
Debt Instrument [Line Items]
Face amount of debt		$ 150,000,000
Term Loan B | Unsecured term loans, net | American Assets Trust, L.P.
Debt Instrument [Line Items]
Face amount of debt		150,000,000
Term Loan C | American Assets Trust, L.P.
Debt Instrument [Line Items]
Face amount of debt		75,000,000
Term Loan C | Unsecured term loans, net | American Assets Trust, L.P.
Debt Instrument [Line Items]
Face amount of debt		$ 75,000,000
Term Loan B & Term Loan C | American Assets Trust, L.P.
Debt Instrument [Line Items]
Number of extensions available | extension		1
Extension term		12 months
Term Loan B & Term Loan C | Unsecured term loans, net | American Assets Trust, L.P.
Debt Instrument [Line Items]
Number of extensions available | extension		1
Extension term		12 months
Term Loan B & Term Loan C | Unsecured term loans, net | American Assets Trust, L.P. | Minimum | Base Rate
Debt Instrument [Line Items]
Basis spread on variable rate		0.20%
Term Loan B & Term Loan C | Unsecured term loans, net | American Assets Trust, L.P. | Maximum | Base Rate
Debt Instrument [Line Items]
Basis spread on variable rate		0.90%
Interest Rate Swap, Year One | Unsecured term loans, net | American Assets Trust, L.P.
Debt Instrument [Line Items]
Fixed interest rate on derivative		5.47%
Interest Rate Swap, Year Two | Unsecured term loans, net | American Assets Trust, L.P.
Debt Instrument [Line Items]
Fixed interest rate on derivative		5.57%