PARTNERS CAPITAL OF AMERICAN ASSETS TRUST, L.P. (Details) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Operating Partnership Units
Capital Unit [Line Items]
Antidilutive securities excluded from computation of EPS	168,529	432,311	196,927	423,502
Common Shares
Capital Unit [Line Items]
Conversion of operating partnership units (in shares)			5,741
American Assets Trust, L.P.
Capital Unit [Line Items]
Noncontrolling common units	17,899,516		17,899,516
Percentage of ownership interests classified as noncontrolling	28.40%		28.40%
American Assets Trust, L.P. | Operating Partnership Units
Capital Unit [Line Items]
Antidilutive securities excluded from computation of EPS	168,529	432,311	196,927	423,502
American Assets Trust, L.P. | Common Shares
Capital Unit [Line Items]
Conversion of operating partnership units (in shares)			5,741