DERIVATIVE AND HEDGING ACTIVITIES (Details) - USD ($)						3 Months Ended
	Jul. 17, 2019	May 11, 2017	Jan. 18, 2017	Sep. 19, 2014	Aug. 19, 2014	Mar. 31, 2021
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Estimated derivative reclassification from Accumulated OCI to Income						$ 1,100,000
American Assets Trust, L.P. | Forward Contracts
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative contract term					7 years
Gain on derivative settlement	$ 500,000	$ 700,000	$ 10,400,000	$ 1,600,000
Designated as Hedging Instrument | Cash Flow Hedging | American Assets Trust, L.P. | Interest Rate Swap, 3/1/2023 | Wells Fargo Bank, N.A.
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional Amount						$ 50,000,000
Effective Date						May 02, 2016
Maturity Date						Mar. 01, 2023
Interest rate swap liability						$ (1,251,000)
Interest Rate Derivative Liabilities, at Fair Value						1,251,000
Designated as Hedging Instrument | Cash Flow Hedging | American Assets Trust, L.P. | Interest Rate Swap, 3/1/2023 | U.S. Bank N.A.
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional Amount						$ 100,000,000
Effective Date						Mar. 01, 2016
Maturity Date						Mar. 01, 2023
Interest rate swap liability						$ (2,533,000)
Interest Rate Derivative Liabilities, at Fair Value						$ 2,533,000