SEGMENT REPORTING - Reconciliation of Segment Profit to Net Income Attributable to Stockholders (Details) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2021	Sep. 30, 2020
Segment Reporting [Abstract]
Total segments’ profit	$ 65,176			$ 53,675			$ 180,555	$ 172,972
General and administrative	(6,827)			(6,438)			(20,574)	(19,937)
Depreciation and amortization	(30,680)			(26,914)			(85,827)	(80,869)
Interest expense	(14,722)			(13,302)			(43,589)	(40,105)
Early extinguishment of debt	0			0			(4,271)	0
Other (expense) income, net	(52)			(531)			(179)	(261)
NET INCOME	12,895	$ 11,487	$ 1,733	6,490	$ 9,826	$ 15,484	26,115	31,800
Net income attributable to restricted shares	(145)			(87)			(417)	(260)
Net income attributable to unitholders in the Operating Partnership	2,709			1,365			5,459	6,778
Net income attributable to American Assets Trust, Inc. stockholders	$ 10,041			$ 5,038			$ 20,239	$ 24,762