DEBT - Narrative (Details)					12 Months Ended
	Jan. 05, 2023 USD ($) extension	Jan. 05, 2022 USD ($) extension	Jan. 26, 2021 USD ($)	Oct. 31, 2014 USD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Jan. 14, 2022	Jul. 30, 2019 USD ($)	Jul. 19, 2017 USD ($)	May 23, 2017 USD ($)	Mar. 01, 2017 USD ($)
Debt Instrument [Line Items]
Repayments of unsecured debt					$ 150,000,000	$ 0	$ 155,375,000
Repayment of unsecured line of credit					36,000,000	0	100,000,000
Third Amended and Restated Credit Facility | Unsecured line of credit
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		175.00%
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					150,000,000	0	155,375,000
Repayment of unsecured line of credit					36,000,000	0	$ 100,000,000
American Assets Trust, L.P. | Secured notes payable
Debt Instrument [Line Items]
Principal balance					75,000,000	75,000,000
American Assets Trust, L.P. | Unsecured Debt
Debt Instrument [Line Items]
Principal balance					$ 1,625,000,000	1,550,000,000
American Assets Trust, L.P. | Unsecured Debt | Base Rate
Debt Instrument [Line Items]
Minimum base rate	0.00%
American Assets Trust, L.P. | Unsecured Debt | Federal Funds Rate
Debt Instrument [Line Items]
Basis spread on variable rate	0.50%
American Assets Trust, L.P. | Unsecured Debt | Secured Overnight Financing Rate
Debt Instrument [Line Items]
Basis spread on variable rate	1.00%
American Assets Trust, L.P. | Unsecured Debt | Secured Overnight Financing Rate | Minimum
Debt Instrument [Line Items]
Basis spread on variable rate	1.20%
American Assets Trust, L.P. | Unsecured Debt | Secured Overnight Financing Rate | Maximum
Debt Instrument [Line Items]
Basis spread on variable rate	1.90%
American Assets Trust, L.P. | 3.375% Senior Unsecured Notes
Debt Instrument [Line Items]
Stated Interest Rate			3.375%		3.375%
Note offering percent			0.98935
Weighted average yield of investment			3.502%
Proceeds from debt, net of issuance costs			$ 489,700,000
American Assets Trust, L.P. | 3.375% Senior Unsecured Notes | Unsecured Debt
Debt Instrument [Line Items]
Stated Interest Rate					3.38%
Face amount of debt			500,000,000
Principal balance					$ 500,000,000	500,000,000
American Assets Trust, L.P. | Senior Guaranteed Notes, Series A | Unsecured Debt
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 line of credit
Debt Instrument [Line Items]
Repayment of unsecured line of credit			$ 100,000,000
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 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, 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 Debt
Debt Instrument [Line Items]
Stated Interest Rate					4.29%							4.29%
Face amount of debt												$ 250,000,000
Principal balance					$ 250,000,000	250,000,000
American Assets Trust, L.P. | Senior Guaranteed Notes, Series E | Unsecured Debt
Debt Instrument [Line Items]
Stated Interest Rate					4.24%						4.24%
Face amount of debt											$ 100,000,000
Principal balance					$ 100,000,000	100,000,000
American Assets Trust, L.P. | Senior Guaranteed Notes, Series F | Unsecured Debt
Debt Instrument [Line Items]
Stated Interest Rate					3.78%					3.78%
Face amount of debt										$ 100,000,000
Principal balance					$ 100,000,000	100,000,000
American Assets Trust, L.P. | Senior Guaranteed Notes, Series G | Unsecured Debt
Debt Instrument [Line Items]
Stated Interest Rate					3.91%				3.91%
Principal balance						150,000,000			$ 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 | Minimum
Debt Instrument [Line Items]
Basis spread on variable rate		0.20%
American Assets Trust, L.P. | Third Amended and Restated Credit Facility | Base Rate | Maximum
Debt Instrument [Line Items]
Basis spread on variable rate		0.70%
American Assets Trust, L.P. | Third Amended and Restated Credit Facility | Unsecured line of credit
Debt Instrument [Line Items]
Debt issuance costs, net, revolving credit facility					$ 1,300,000
Weighted average interest rate					6.17%
American Assets Trust, L.P. | Third Amended and Restated Credit Facility | Unsecured line of credit | 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 | 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 | 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 line of credit | 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 | 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 Debt
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 Debt | Base Rate
Debt Instrument [Line Items]
Minimum base rate		1.00%
American Assets Trust, L.P. | Third Amended and Restated Credit Facility | Unsecured Debt | 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 Debt | 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 Debt | 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 Debt | Secured Overnight Financing Rate | Maximum
Debt Instrument [Line Items]
Basis spread on variable rate		1.70%
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 Debt
Debt Instrument [Line Items]
Face amount of debt	150,000,000
Principal balance					$ 150,000,000	100,000,000
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 Debt
Debt Instrument [Line Items]
Face amount of debt	$ 75,000,000
Principal balance					75,000,000	50,000,000
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 Debt
Debt Instrument [Line Items]
Face amount of debt					225,000,000	150,000,000
Number of extensions available | extension	1
Extension term	12 months
American Assets Trust, L.P. | Term Loan B & Term Loan C | Unsecured Debt | 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 Debt | 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 Debt
Debt Instrument [Line Items]
Fixed interest rate on derivative	5.47%
American Assets Trust, L.P. | Interest Rate Swap, Year Two | Unsecured Debt
Debt Instrument [Line Items]
Fixed interest rate on derivative	5.57%
American Assets Trust, L.P. | Term Loan A | Unsecured Debt
Debt Instrument [Line Items]
Principal balance					$ 100,000,000	$ 100,000,000
Interest Rate Swap | American Assets Trust, L.P. | Term Loan A
Debt Instrument [Line Items]
Fixed interest rate on derivative					2.70%			2.70%