EQUITY OF AMERICAN ASSETS TRUST, INC. (Details)				3 Months Ended
	Apr. 02, 2019 USD ($) $ / shares shares	Mar. 02, 2018 Agent	May 27, 2015 USD ($) Agent	Mar. 31, 2019 USD ($) $ / shares shares	Mar. 31, 2018 USD ($) shares
Equity [Line Items]
Proceeds from issuance of common stock				$ 7,034,000
Noncash compensation expense				1,100,000	$ 700,000
Unrecognized compensation expense				$ 5,400,000
Weighted average unvested shares outstanding (in shares) | shares				333,275	263,606
At The Market Equity Program
Equity [Line Items]
Number of sales agents | Agent		1	5
Aggregate offering price of common share			$ 250,000,000.0
Common shares issued (in shares) | shares				162,531
Weighted average price per share | $ / shares				$ 45.53
Remaining capacity to issue				$ 168,800,000
Operating Partnership Units
Equity [Line Items]
Antidilutive securities excluded from computation of EPS (in shares) | shares				333,275	17,458,586
Subsequent Event | At The Market Equity Program
Equity [Line Items]
Common shares issued (in shares) | shares	519,382
Weighted average price per share | $ / shares	$ 45.57
Proceeds from issuance of common stock	$ 23,400,000