SEGMENT REPORTING - Reconciliation of Segment Profit to Net Income Attributable to Stockholders (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Segment Reporting [Abstract]
Total Segments' profit	$ 45,628	$ 44,070	$ 132,573	$ 125,974
General and administrative	(6,357)	(4,682)	(16,161)	(13,929)
Depreciation and amortization	(15,761)	(16,352)	(46,154)	(50,902)
Interest expense	11,258	13,325	34,250	40,396
Gain on sale of real estate	7,121	0	7,121	0
Other income (expense), net	(347)	(621)	(440)	352
NET INCOME	19,026	9,090	42,689	21,099
Net income attributable to restricted shares	(32)	(95)	(115)	(259)
Net income attributable to unitholders in the Operating Partnership	5,432	2,578	12,277	6,108
NET INCOME ATTRIBUTABLE TO AMERICAN ASSETS TRUST, INC. STOCKHOLDERS	$ 13,562	$ 6,417	$ 30,297	$ 14,732