Equity of American Assets Trust, Inc. Restricted Common Stock Issued (Details) (Restricted Stock, USD $)	0 Months Ended
	Dec. 01, 2014	Jun. 17, 2014	Mar. 25, 2014	Jul. 13, 2013	Jul. 10, 2012	Jan. 19, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted, Weighted Average Grant Date Fair Value		$ 34.10		$ 31.97	$ 25.05
Granted, Shares	98,765	5,864	112,119	5,004	8,015	2,000
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted, Weighted Average Grant Date Fair Value	36.28		28.89			11.91
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted, Weighted Average Grant Date Fair Value	36.32		31.25			12.61