EQUITY Computation of Basic and Diluted EPS (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Equity [Abstract]
Income from continuing operations	$ 6,658	$ 4,865
Less: Net income attributable to restricted shares	(70)	(132)
Less: Income from continuing operations attributable to unitholders in the Operating Partnership	(1,986)	(1,495)
Income from continuing operations attributable to American Assets Trust, Inc. common stockholders-basic	4,602	3,238
Income from continuing operations attributable to American Assets Trust, Inc. common stockholders-basic	4,602	3,238
Net income attributable to common stockholders-diluted	$ 6,588	$ 4,733
Weighted average common shares outstanding-basic	40,582,792	39,033,013
Effect of dilutive securities-conversion of Operating Partnership units	17,909,681	18,023,435
Weighted average common shares outstanding - diluted	58,492,473	57,056,448
Earnings per common share, basic	$ 0.11	$ 0.08
Earnings per common share, diluted	$ 0.11	$ 0.08