DEBT - Narrative (Details)					3 Months Ended
	Jan. 05, 2023 USD ($) extension	Jan. 05, 2022 USD ($) extension	Jan. 26, 2021 USD ($)	Oct. 31, 2014 USD ($)	Mar. 31, 2024 USD ($)	Mar. 31, 2023 USD ($)	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
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%
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
American Assets Trust, L.P. | Unsecured term loans, net | Secured Overnight Financing Rate
Debt Instrument [Line Items]
Basis spread on variable rate	1.00%
American Assets Trust, L.P. | Unsecured term loans, net | Secured Overnight Financing Rate | Minimum
Debt Instrument [Line Items]
Basis spread on variable rate	1.20%
American Assets Trust, L.P. | Unsecured term loans, net | Secured Overnight Financing Rate | Maximum
Debt Instrument [Line Items]
Basis spread on variable rate	1.90%
American Assets Trust, L.P. | Unsecured term loans, net | Federal Funds Rate
Debt Instrument [Line Items]
Basis spread on variable rate	0.50%
American Assets Trust, L.P. | Unsecured term loans, net | Base Rate
Debt Instrument [Line Items]
Basis spread on variable rate	0.00%
American Assets Trust, L.P. | 3.375% Senior Notes | Unsecured term loans, net
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%
American Assets Trust, L.P. | Senior Guaranteed Notes, Series A | Unsecured term loans, net
Debt Instrument [Line Items]
Repayments of unsecured debt			$ 150,000,000
Make-whole payment			3,900,000
American Assets Trust, L.P. | Second Amended and Restated Credit Facility | Unsecured term loans, net
Debt Instrument [Line Items]
Repayment of unsecured line of credit			$ 100,000,000
American Assets Trust, L.P. | Note Purchase Agreement | Senior Guaranteed Notes, Series A
Debt Instrument [Line Items]
Stated Interest Rate				4.04%
Face amount of debt				$ 150,000,000
American Assets Trust, L.P. | Note Purchase Agreement | Senior Guaranteed Notes
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%
American Assets Trust, L.P. | Note Purchase Agreement | Senior Guaranteed Notes, Series B
Debt Instrument [Line Items]
Stated Interest Rate				4.45%
Face amount of debt				$ 100,000,000
American Assets Trust, L.P. | Note Purchase Agreement | Senior Guaranteed Notes, Series C
Debt Instrument [Line Items]
Stated Interest Rate				4.50%
Face amount of debt				$ 100,000,000
American Assets Trust, L.P. | Senior Guaranteed Notes, Series D | Unsecured term loans, net
Debt Instrument [Line Items]
Stated Interest Rate					4.29%						4.29%
Face amount of debt											$ 250,000,000
American Assets Trust, L.P. | Senior Guaranteed Notes, Series E | Unsecured term loans, net
Debt Instrument [Line Items]
Stated Interest Rate					4.24%					4.24%
Face amount of debt										$ 100,000,000
American Assets Trust, L.P. | Senior Guaranteed Notes, Series F | Unsecured term loans, net
Debt Instrument [Line Items]
Stated Interest Rate					3.78%				3.78%
Face amount of debt									$ 100,000,000
American Assets Trust, L.P. | Senior Guaranteed Notes, Series G | Unsecured term loans, net
Debt Instrument [Line Items]
Stated Interest Rate					3.91%			3.91%
Face amount of debt								$ 150,000,000
American Assets Trust, L.P. | Third Amended and Restated Credit Facility
Debt Instrument [Line Items]
Revolving credit facility borrowing limit, maximum borrowing capacity		$ 500,000,000
American Assets Trust, L.P. | Third Amended and Restated Credit Facility | Base Rate
Debt Instrument [Line Items]
Basis spread on variable rate		1.00%
American Assets Trust, L.P. | Third Amended and Restated Credit Facility | Unsecured line of credit, net
Debt Instrument [Line Items]
Debt issuance costs, net, revolving credit facility					$ 1,130,000
Weighted average interest rate					6.54%
American Assets Trust, L.P. | Third Amended and Restated Credit Facility | Unsecured line of credit, net | Revolving Credit Facility
Debt Instrument [Line Items]
Revolving credit facility borrowing limit, maximum borrowing capacity		$ 400,000,000
American Assets Trust, L.P. | Third Amended and Restated Credit Facility | Unsecured line of credit, net | Revolving Credit Facility | Secured Overnight Financing Rate | Minimum
Debt Instrument [Line Items]
Basis spread on variable rate		1.05%
American Assets Trust, L.P. | Third Amended and Restated Credit Facility | Unsecured line of credit, net | Revolving Credit Facility | Secured Overnight Financing Rate | Maximum
Debt Instrument [Line Items]
Basis spread on variable rate		1.50%
American Assets Trust, L.P. | Third Amended and Restated Credit Facility | Unsecured line of credit, net | Revolving Credit Facility | Base Rate | Minimum
Debt Instrument [Line Items]
Basis spread on variable rate		0.10%
American Assets Trust, L.P. | Third Amended and Restated Credit Facility | Unsecured line of credit, net | Revolving Credit Facility | Base Rate | Maximum
Debt Instrument [Line Items]
Basis spread on variable rate		0.50%
American Assets Trust, L.P. | Third Amended and Restated Credit Facility | Unsecured term loans, net
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
American Assets Trust, L.P. | Third Amended and Restated Credit Facility | Unsecured term loans, net | Secured Overnight Financing Rate
Debt Instrument [Line Items]
Basis spread on variable rate		1.00%
American Assets Trust, L.P. | Third Amended and Restated Credit Facility | Unsecured term loans, net | Secured Overnight Financing Rate | Minimum
Debt Instrument [Line Items]
Basis spread on variable rate		1.20%
American Assets Trust, L.P. | Third Amended and Restated Credit Facility | Unsecured term loans, net | Secured Overnight Financing Rate | Maximum
Debt Instrument [Line Items]
Basis spread on variable rate		1.70%
American Assets Trust, L.P. | Third Amended and Restated Credit Facility | Unsecured term loans, net | Federal Funds Rate
Debt Instrument [Line Items]
Basis spread on variable rate		0.50%
American Assets Trust, L.P. | Third Amended and Restated Credit Facility | Unsecured term loans, net | Base Rate | Minimum
Debt Instrument [Line Items]
Basis spread on variable rate		0.20%
American Assets Trust, L.P. | Third Amended and Restated Credit Facility | Unsecured term loans, net | Base Rate | Maximum
Debt Instrument [Line Items]
Basis spread on variable rate		0.70%
American Assets Trust, L.P. | Term Loan B
Debt Instrument [Line Items]
Face amount of debt	$ 150,000,000
American Assets Trust, L.P. | Term Loan B | Unsecured term loans, net
Debt Instrument [Line Items]
Face amount of debt	150,000,000
American Assets Trust, L.P. | Term Loan C
Debt Instrument [Line Items]
Face amount of debt	75,000,000
American Assets Trust, L.P. | Term Loan C | Unsecured term loans, net
Debt Instrument [Line Items]
Face amount of debt	$ 75,000,000
American Assets Trust, L.P. | Term Loan B & Term Loan C
Debt Instrument [Line Items]
Number of extensions available | extension	1
Extension term	12 months
American Assets Trust, L.P. | Term Loan B & Term Loan C | Unsecured term loans, net
Debt Instrument [Line Items]
Number of extensions available | extension	1
Extension term	12 months
American Assets Trust, L.P. | Term Loan B & Term Loan C | Unsecured term loans, net | Base Rate | Minimum
Debt Instrument [Line Items]
Basis spread on variable rate	0.20%
American Assets Trust, L.P. | Term Loan B & Term Loan C | Unsecured term loans, net | Base Rate | Maximum
Debt Instrument [Line Items]
Basis spread on variable rate	0.90%
American Assets Trust, L.P. | Interest Rate Swap, Year One | Unsecured term loans, net
Debt Instrument [Line Items]
Fixed interest rate on derivative	5.47%
American Assets Trust, L.P. | Interest Rate Swap, Year Two | Unsecured term loans, net
Debt Instrument [Line Items]
Fixed interest rate on derivative	5.57%
Interest Rate Swap | American Assets Trust, L.P. | Term Loan A
Debt Instrument [Line Items]
Fixed interest rate on derivative					2.70%		2.70%