Partners Capital of American Assets Trust, L.P. (Details) - shares	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Capital Unit [Line Items]
Noncontrolling common units	17,905,257
Noncontrolling Interest, Ownership Percentage by Parent	70.70%
Percentage of ownership interests classified as noncontrolling	29.30%
Common Stock
Capital Unit [Line Items]
Conversion of operating partnership units (in shares)	11,852	106,326	372,654