Partners Capital of American Assets Trust, L.P. (Details) - shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Capital Unit [Line Items]
Noncontrolling Interest, Ownership Percentage by Parent	71.70%
Common Stock
Capital Unit [Line Items]
Conversion of operating partnership units (in shares)	5,741	11,852	106,326
American Assets Trust, L.P.
Capital Unit [Line Items]
Noncontrolling common units	17,899,516
Percentage of ownership interests classified as noncontrolling	28.30%
American Assets Trust, L.P. | Common Stock
Capital Unit [Line Items]
Conversion of operating partnership units (in shares)	5,741	11,852	106,326