EQUITY Computation of Basic and Diluted EPS (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Equity [Abstract]
Income from continuing operations	$ 5,351	$ 4,564	$ 12,009	$ 9,429
Less: Net income attributable to restricted shares	(94)	(133)	(164)	(265)
Less: Income from continuing operations attributable to unitholders in the Operating Partnership	(1,544)	(1,354)	(3,530)	(2,849)
Net income attributable to common stockholders—basic	3,713	3,077	8,315	6,315
Income from operations attributable to American Assets Trust, Inc. common stockholders—basic	3,713	3,077	8,315	6,315
Net income attributable to common stockholders-diluted	$ 5,257	$ 4,431	$ 11,845	$ 9,164
Weighted average common shares outstanding-basic	41,816,379	39,460,086	41,202,993	39,247,729
Effect of dilutive securities-conversion of Operating Partnership units	17,905,257	17,969,751	17,907,457	17,996,445
Weighted average common shares outstanding - diluted	59,721,636	57,429,837	59,110,450	57,244,174
Earnings per common share, basic	$ 0.09	$ 0.08	$ 0.20	$ 0.16
Earnings per common share, diluted	$ 0.09	$ 0.08	$ 0.20	$ 0.16