SEGMENT REPORTING - Reconciliation of Segment Profit to Net Income Attributable to Stockholders (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Segment Reporting [Abstract]
Total Segments' profit	$ 51,766	$ 46,397
General and administrative	(5,567)	(5,082)
Depreciation and amortization	(33,279)	(17,986)
Interest expense	13,820	13,331
Other income, net	209	310
NET (LOSS) INCOME	(691)	10,308
Net loss (income) attributable to restricted shares	72	(60)
Net loss (income) attributable to unitholders in the Operating Partnership	(166)	2,861
NET (LOSS) INCOME ATTRIBUTABLE TO AMERICAN ASSETS TRUST, INC. STOCKHOLDERS	$ (453)	$ 7,387