SEGMENT REPORTING - Reconciliation of Segment Profit to Net Income Attributable to Stockholders (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2019	Jun. 30, 2018
Segment Reporting Information [Line Items]
Total Segments' profit	$ 53,012		$ 55,513		$ 108,489	$ 107,279
General and administrative	(5,943)		(5,396)		(12,016)	(10,963)
Depreciation and amortization	(22,582)		(32,868)		(43,165)	(66,147)
Interest expense	(13,129)		(12,688)		(26,478)	(26,508)
Gain on sale of real estate	633		0		633	0
Other (expense) income, net	(50)		(148)		(279)	61
NET INCOME	11,941	$ 15,243	4,413	$ (691)	27,184	3,722
Net income attributable to restricted shares	(92)		(216)		(185)	(144)
Net income attributable to unitholders in the Operating Partnership	2,933		1,125		6,988	959
NET INCOME ATTRIBUTABLE TO AMERICAN ASSETS TRUST, INC. STOCKHOLDERS	$ 8,916		$ 3,072		$ 20,011	$ 2,619