EQUITY OF AMERICAN ASSETS TRUST, INC. - Computation of Basic and Diluted EPS (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Equity [Abstract]
Net income from operations	$ 10,721	$ 11,379
Less: Net income attributable to restricted shares	(43)	(43)
Less: Income from continuing operations attributable to unitholders in the Operating Partnership	(3,027)	(3,309)
Net income attributable to common stockholders—basic	7,651	8,027
Income from operations attributable to American Assets Trust, Inc. common stockholders—basic	7,651	8,027
Net income attributable to common stockholders-diluted	$ 10,678	$ 11,336
Weighted average common shares outstanding-basic	45,233,873	43,419,762
Effect of dilutive securities-conversion of Operating Partnership units	17,899,516	17,901,685
Weighted average common shares outstanding - diluted	63,133,389	61,321,447
Earnings per common share, basic (in USD per share)	$ 0.17	$ 0.18
Earnings per common share, diluted (in USD per share)	$ 0.17	$ 0.18