DEBT (Details)				6 Months Ended
	May 02, 2016 USD ($)	Mar. 01, 2016 USD ($)	Jan. 09, 2014 USD ($) Extension_Option	Jun. 30, 2016 USD ($)	Dec. 31, 2015 USD ($)
Debt Instrument [Line Items]
Unsecured line of credit				$ 0	$ 30,000,000
Unsecured term loans, net | Term Loan B | Base Rate
Debt Instrument [Line Items]
Basis spread on federal funds rate		0.50%
Basis spread on Eurodollar rate		1.00%
Unsecured term loans, net | Amended and Restated Credit Facility | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Description of variable rate basis			LIBOR
Unsecured line of credit | Amended and Restated Credit Facility | Base Rate
Debt Instrument [Line Items]
Basis spread on federal funds rate			0.50%
Basis spread on Eurodollar rate			1.00%
American Assets Trust, L.P.
Debt Instrument [Line Items]
Unsecured line of credit				$ 0	$ 30,000,000
American Assets Trust, L.P. | Term Loan B
Debt Instrument [Line Items]
Term of debt instrument		7 years
Face amount of debt		$ 100,000,000
Stated Maturity Date		Mar. 01, 2023
American Assets Trust, L.P. | Term Loan B | Minimum | Base Rate
Debt Instrument [Line Items]
Basis spread on variable rate		0.70%
American Assets Trust, L.P. | Term Loan B | Maximum | Base Rate
Debt Instrument [Line Items]
Basis spread on variable rate		1.35%
American Assets Trust, L.P. | Term Loan B | Interest Rate Swap
Debt Instrument [Line Items]
Derivative fixed interest rate (in percent)				3.15%
American Assets Trust, L.P. | Term Loan C
Debt Instrument [Line Items]
Term of debt instrument	7 years	7 years
Face amount of debt	$ 50,000,000
Stated Maturity Date	Mar. 01, 2023
American Assets Trust, L.P. | Term Loan C | Interest Rate Swap
Debt Instrument [Line Items]
Derivative fixed interest rate (in percent)				3.14%
American Assets Trust, L.P. | Amended and Restated Credit Facility
Debt Instrument [Line Items]
Revolving credit facility borrowing limit, maximum borrowing capacity			$ 350,000,000
Additional borrowing capacity			$ 250,000,000
American Assets Trust, L.P. | Amended and Restated Credit Facility | Minimum | Base Rate | Revolving Credit Facility
Debt Instrument [Line Items]
Basis spread on variable rate			0.35%
American Assets Trust, L.P. | Amended and Restated Credit Facility | Maximum | Base Rate | Revolving Credit Facility
Debt Instrument [Line Items]
Basis spread on variable rate			0.95%
American Assets Trust, L.P. | Unsecured term loans, net | Term Loan B
Debt Instrument [Line Items]
Face amount of debt				$ 100,000,000
Stated Maturity Date				Mar. 01, 2023
American Assets Trust, L.P. | Unsecured term loans, net | Term Loan B | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Description of variable rate basis		LIBOR
American Assets Trust, L.P. | Unsecured term loans, net | Term Loan B | Base Rate
Debt Instrument [Line Items]
Prime rate		prime rate
0% rate		0
Federal funds rate		federal funds rate
Eurodollar rate		Eurodollar
American Assets Trust, L.P. | Unsecured term loans, net | Term Loan B | Minimum | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Basis spread on variable rate		1.70%
American Assets Trust, L.P. | Unsecured term loans, net | Term Loan B | Maximum | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Basis spread on variable rate		2.35%
American Assets Trust, L.P. | Unsecured term loans, net | Term Loan C
Debt Instrument [Line Items]
Face amount of debt				$ 50,000,000
Stated Maturity Date				Mar. 01, 2023
American Assets Trust, L.P. | Unsecured term loans, net | Amended and Restated Credit Facility
Debt Instrument [Line Items]
Revolving credit facility borrowing limit, maximum borrowing capacity			$ 100,000,000
Debt extension options | Extension_Option			3
Extension term			12 months
American Assets Trust, L.P. | Unsecured term loans, net | Amended and Restated Credit Facility | Minimum | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Basis spread on variable rate			1.30%
American Assets Trust, L.P. | Unsecured term loans, net | Amended and Restated Credit Facility | Minimum | Base Rate
Debt Instrument [Line Items]
Basis spread on variable rate			0.30%
American Assets Trust, L.P. | Unsecured term loans, net | Amended and Restated Credit Facility | Maximum | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Basis spread on variable rate			1.90%
American Assets Trust, L.P. | Unsecured term loans, net | Amended and Restated Credit Facility | Maximum | Base Rate
Debt Instrument [Line Items]
Basis spread on variable rate			0.90%
American Assets Trust, L.P. | Unsecured line of credit | Amended and Restated Credit Facility
Debt Instrument [Line Items]
Unsecured line of credit				$ 0
Weighted average interest rate				1.77%
American Assets Trust, L.P. | Unsecured line of credit | Amended and Restated Credit Facility | Revolving Credit Facility
Debt Instrument [Line Items]
Revolving credit facility borrowing limit, maximum borrowing capacity			$ 250,000,000
Debt extension options | Extension_Option			2
Extension term			6 months
American Assets Trust, L.P. | Unsecured line of credit | Amended and Restated Credit Facility | London Interbank Offered Rate (LIBOR) | Revolving Credit Facility
Debt Instrument [Line Items]
Description of variable rate basis			LIBOR
American Assets Trust, L.P. | Unsecured line of credit | Amended and Restated Credit Facility | Base Rate
Debt Instrument [Line Items]
Description of variable rate basis			base rate
Prime rate			prime rate
Federal funds rate			federal funds rate
Eurodollar rate			Eurodollar
American Assets Trust, L.P. | Unsecured line of credit | Amended and Restated Credit Facility | Minimum | London Interbank Offered Rate (LIBOR) | Revolving Credit Facility
Debt Instrument [Line Items]
Basis spread on variable rate			1.35%
American Assets Trust, L.P. | Unsecured line of credit | Amended and Restated Credit Facility | Maximum | London Interbank Offered Rate (LIBOR) | Revolving Credit Facility
Debt Instrument [Line Items]
Basis spread on variable rate			1.95%