EQUITY OF AMERICAN ASSETS TRUST, INC. - ATM Equity Program (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended	6 Months Ended
	Jun. 14, 2019	Jun. 30, 2019	Jun. 30, 2019
Equity [Line Items]
Proceeds from issuance of common stock	$ 472,600		$ 503,014
At The Market Equity Program
Equity [Line Items]
Common shares issued (shares)		519,382	681,913
Weighted average price per share		$ 45.57	$ 45.56
Proceeds, gross		$ 23,671	$ 31,071
Proceeds from issuance of common stock		23,355	30,388
At The Market Equity Program | Sales agent compensation
Equity [Line Items]
Sales agent compensation and offering costs		(237)	(311)
At The Market Equity Program | Other offering costs
Equity [Line Items]
Sales agent compensation and offering costs		$ (79)	$ (372)