SEGMENT REPORTING - Reconciliation of Segment Profit to Net Income Attributable to Stockholders (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Segment Reporting [Abstract]
Total Segments' profit	$ 55,513	$ 49,361	$ 107,279	$ 95,758
General and administrative	(5,396)	(5,131)	(10,963)	(10,213)
Depreciation and amortization	(32,868)	(24,182)	(66,147)	(42,168)
Interest expense	12,688	12,652	26,508	25,983
Other (expense) income, net	(148)	192	61	502
NET INCOME	4,413	7,588	3,722	17,896
Net income attributable to restricted shares	(216)	(61)	(144)	(121)
Net income attributable to unitholders in the Operating Partnership	1,125	2,008	959	4,869
NET INCOME ATTRIBUTABLE TO AMERICAN ASSETS TRUST, INC. STOCKHOLDERS	$ 3,072	$ 5,519	$ 2,619	$ 12,906