DEBT - Summary of Total Secured Notes Payable Outstanding (Details) - American Assets Trust, L.P. - USD ($) $ in Thousands		9 Months Ended
		Sep. 30, 2015	Dec. 31, 2014
Shops At Kalakaua
Debt Instrument [Line Items]
Stated Interest Rate	[1],[2]	0.00%
Stated Maturity Date	[1],[2]	May 01, 2015
The Land Mark at One Market
Debt Instrument [Line Items]
Stated Interest Rate	[1],[3]	0.00%
Stated Maturity Date	[1],[3]	Jul. 05, 2015
Del Monte Center
Debt Instrument [Line Items]
Stated Interest Rate	[1],[4]	0.00%
Stated Maturity Date	[1],[4]	Jul. 08, 2015
First And Main
Debt Instrument [Line Items]
Stated Interest Rate	[1]	3.97%
Stated Maturity Date	[1]	Jul. 01, 2016
Imperial Beach Gardens
Debt Instrument [Line Items]
Stated Interest Rate	[1]	6.16%
Stated Maturity Date	[1]	Sep. 01, 2016
Mariners Point
Debt Instrument [Line Items]
Stated Interest Rate	[1]	6.09%
Stated Maturity Date	[1]	Sep. 01, 2016
South Bay Marketplace
Debt Instrument [Line Items]
Stated Interest Rate	[1]	5.48%
Stated Maturity Date	[1]	Feb. 10, 2017
Waikiki Beach Walk - Retail
Debt Instrument [Line Items]
Stated Interest Rate	[1]	5.39%
Stated Maturity Date	[1]	Jul. 01, 2017
Solana Beach Corporate Centre Three To Four
Debt Instrument [Line Items]
Stated Interest Rate	[5]	6.39%
Stated Maturity Date	[5]	Aug. 01, 2017
Loma Palisades
Debt Instrument [Line Items]
Stated Interest Rate	[1]	6.09%
Stated Maturity Date	[1]	Jul. 01, 2018
One Beach Street
Debt Instrument [Line Items]
Stated Interest Rate	[1]	3.94%
Stated Maturity Date	[1]	Apr. 01, 2019
Torrey Reserve North Court
Debt Instrument [Line Items]
Stated Interest Rate	[5]	7.22%
Stated Maturity Date	[5]	Jun. 01, 2019
Torrey Reserve
Debt Instrument [Line Items]
Stated Interest Rate	[5]	6.36%
Stated Maturity Date	[5]	Jun. 01, 2020
Solana Beach Corporate Centre One To Two
Debt Instrument [Line Items]
Stated Interest Rate	[5]	5.91%
Stated Maturity Date	[5]	Jun. 01, 2020
Solana Beach Towne Centre
Debt Instrument [Line Items]
Stated Interest Rate	[5]	5.91%
Stated Maturity Date	[5]	Jun. 01, 2020
City Center Bellevue
Debt Instrument [Line Items]
Stated Interest Rate	[1]	3.98%
Stated Maturity Date	[1]	Nov. 01, 2022
Secured Debt
Debt Instrument [Line Items]
Total		$ 584,437	$ 819,983
Unamortized fair value adjustment		(4,988)	(7,172)
Total Debt Outstanding		$ 579,449	812,811
Period of amortization schedule (in years)		30 years
Secured Debt | Shops At Kalakaua
Debt Instrument [Line Items]
Secured notes payable, Principal Balance	[1],[2]	$ 0	19,000
Secured Debt | The Land Mark at One Market
Debt Instrument [Line Items]
Secured notes payable, Principal Balance	[1],[3]	0	133,000
Secured Debt | Del Monte Center
Debt Instrument [Line Items]
Secured notes payable, Principal Balance	[1],[4]	0	82,300
Secured Debt | First And Main
Debt Instrument [Line Items]
Secured notes payable, Principal Balance	[1]	84,500	84,500
Secured Debt | Imperial Beach Gardens
Debt Instrument [Line Items]
Secured notes payable, Principal Balance	[1]	20,000	20,000
Secured Debt | Mariners Point
Debt Instrument [Line Items]
Secured notes payable, Principal Balance	[1]	7,700	7,700
Secured Debt | South Bay Marketplace
Debt Instrument [Line Items]
Secured notes payable, Principal Balance	[1]	23,000	23,000
Secured Debt | Waikiki Beach Walk - Retail
Debt Instrument [Line Items]
Secured notes payable, Principal Balance	[1]	130,310	130,310
Secured Debt | Solana Beach Corporate Centre Three To Four
Debt Instrument [Line Items]
Secured notes payable, Principal Balance	[5]	36,038	36,376
Secured Debt | Loma Palisades
Debt Instrument [Line Items]
Secured notes payable, Principal Balance	[1]	73,744	73,744
Secured Debt | One Beach Street
Debt Instrument [Line Items]
Secured notes payable, Principal Balance	[1]	21,900	21,900
Secured Debt | Torrey Reserve North Court
Debt Instrument [Line Items]
Secured notes payable, Principal Balance	[5]	20,833	21,075
Secured Debt | Torrey Reserve
Debt Instrument [Line Items]
Secured notes payable, Principal Balance	[5]	7,023	7,101
Secured Debt | Solana Beach Corporate Centre One To Two
Debt Instrument [Line Items]
Secured notes payable, Principal Balance	[5]	11,167	11,302
Secured Debt | Solana Beach Towne Centre
Debt Instrument [Line Items]
Secured notes payable, Principal Balance	[5]	37,222	37,675
Secured Debt | City Center Bellevue
Debt Instrument [Line Items]
Secured notes payable, Principal Balance	[1]	$ 111,000	$ 111,000

[1] Interest only.

[2] Loan repaid in full, without premium or penalty, on February 2, 2015.

[3] Loan repaid in full, without premium or penalty, on April 6, 2015.

[4] Loan repaid in full, without premium or penalty, on February 6, 2015.

[5] Principal payments based on a 30-year amortization schedule.