SUBSEQUENT EVENTS (Details) - USD ($)	Mar. 31, 2017	Apr. 07, 2016	Mar. 29, 2016	Mar. 23, 2016	Jan. 29, 2016
American Assets Trust, L.P. | Scenario, Forecast | Unsecured term loans, net
Subsequent Event [Line Items]
Term of debt instrument	10 years
Interest Rate Swap | American Assets Trust, L.P.
Subsequent Event [Line Items]
Derivative contract term			10 years
Designated as Hedging Instrument | Interest Rate Swap | Cash Flow Hedging
Subsequent Event [Line Items]
Notional Amount			$ 150,000,000
Derivative fixed interest rate (in percent)			1.88%
Designated as Hedging Instrument | Interest Rate Swap | American Assets Trust, L.P. | Cash Flow Hedging
Subsequent Event [Line Items]
Effective Date			Mar. 31, 2017	May 02, 2016	Mar. 01, 2016
Derivative contract term				7 years	7 years
Notional Amount				$ 50,000,000	$ 100,000,000
Maturity Date			Mar. 31, 2027	Mar. 01, 2023	Mar. 01, 2023
Derivative fixed interest rate (in percent)				1.441%	1.4485%
Subsequent Event | American Assets Trust, L.P. | Scenario, Forecast | Unsecured term loans, net
Subsequent Event [Line Items]
Derivative contract term		10 years
Term of debt instrument		10 years
Subsequent Event | Designated as Hedging Instrument | Interest Rate Swap | Cash Flow Hedging
Subsequent Event [Line Items]
Notional Amount		$ 100,000,000
Derivative fixed interest rate (in percent)		1.748%
Subsequent Event | Designated as Hedging Instrument | Interest Rate Swap | American Assets Trust, L.P. | Cash Flow Hedging
Subsequent Event [Line Items]
Effective Date		Mar. 31, 2017
Maturity Date		Mar. 31, 2027