EQUITY OF AMERICAN ASSETS TRUST, INC. - ATM Equity Program (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2017	Sep. 30, 2016
Equity [Line Items]
Proceeds from issuance of common stock	$ 0	$ 30,075	$ 9,665
At The Market Equity Program
Equity [Line Items]
Common shares issued (in shares)	0	700,000
Weighted average price per share		$ 43.46
Proceeds, gross	$ 0	$ 30,425
At The Market Equity Program | Sales agent compensation
Equity [Line Items]
Sales agent compensation and offering costs	0	(304)
At The Market Equity Program | Offering costs
Equity [Line Items]
Sales agent compensation and offering costs	$ 0	$ (46)