SEGMENT REPORTING - Reconciliation of Segment Profit to Net Income Attributable to Stockholders (Details) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019
Segment Reporting [Abstract]
Total segments’ profit	$ 53,675			$ 63,431			$ 172,972	$ 171,920
General and administrative	(6,438)			(6,479)			(19,937)	(18,495)
Depreciation and amortization	(26,914)			(26,568)			(80,869)	(69,733)
Interest expense	(13,302)			(13,734)			(40,105)	(40,212)
Gain on sale of real estate	0			0			0	633
Other (expense) income, net	(531)			(131)			(261)	(410)
NET INCOME	6,490	$ 9,826	$ 15,484	16,519	$ 11,941	$ 15,243	31,800	43,703
Net income attributable to restricted shares	(87)			(92)			(260)	(277)
Net income attributable to unitholders in the Operating Partnership	1,365			3,565			6,778	10,553
NET INCOME ATTRIBUTABLE TO AMERICAN ASSETS TRUST, INC. STOCKHOLDERS	$ 5,038			$ 12,862			$ 24,762	$ 32,873