Partners Capital of American Assets Trust, L.P. (Details) - shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Capital Unit [Line Items]
Ownership percent by parent	71.80%
Common Stock
Capital Unit [Line Items]
Conversion of operating partnership units (in shares)	10,694	5,741	11,852
American Assets Trust, L.P.
Capital Unit [Line Items]
Noncontrolling common units (in shares)	17,888,822
Percentage of ownership interests classified as noncontrolling	28.20%
American Assets Trust, L.P. | Common Stock
Capital Unit [Line Items]
Conversion of operating partnership units (in shares)	10,694	5,741	11,852