PARTNERS CAPITAL OF AMERICAN ASSETS TRUST, L.P. (Details) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Operating Partnership Units
Capital Unit [Line Items]
Antidilutive securities excluded from computation of EPS (in shares)	231,977	169,963	232,041	171,760
Common Shares
Capital Unit [Line Items]
Conversion of operating partnership units (in shares)			693,842
American Assets Trust, L.P.
Capital Unit [Line Items]
Noncontrolling common units (in shares)	17,194,980		17,194,980
Percentage of ownership interests classified as noncontrolling	26.80%		26.80%
American Assets Trust, L.P. | Operating Partnership Units
Capital Unit [Line Items]
Antidilutive securities excluded from computation of EPS (in shares)	231,977	169,963	232,041	171,760
Limited Partner | American Assets Trust, L.P.
Capital Unit [Line Items]
Common unit conversion ratio			1