EQUITY OF AMERICAN ASSETS TRUST, INC. (Details)					3 Months Ended		9 Months Ended
	Jun. 16, 2015 shares	May. 27, 2015 USD ($) Agent	Mar. 09, 2015 USD ($) $ / shares shares	May. 06, 2013 USD ($) Agent	Sep. 30, 2015 USD ($) shares	Sep. 30, 2014 USD ($) shares	Sep. 30, 2015 USD ($) shares	Sep. 30, 2014 USD ($) shares
Equity [Line Items]
Noncash compensation expense					$ 400,000	$ 1,100,000	$ 2,100,000	$ 2,600,000
Unrecognized compensation expense					$ 1,600,000		$ 1,600,000
Weighted average unvested shares outstanding | shares					168,529	432,311	196,927	423,502
Restricted Stock Units (RSUs)
Equity [Line Items]
Granted, Shares | shares	5,044						5,044
At The Market Equity Program
Equity [Line Items]
Aggregate offering price of common share		$ 250,000,000.0		$ 150,000,000.0
Remaining capacity to issue					$ 216,600,000		$ 216,600,000
Common shares issued (in shares) | shares					466,525		1,612,451
Gross proceeds from issuance of common stock					$ 19,059,000		$ 65,740,000
Private Placement | Explorer Insurance Company | Board of Directors Chairman
Equity [Line Items]
Common shares issued (in shares) | shares			200,000
Share price (in dollars per share) | $ / shares			$ 40.54
Gross proceeds from issuance of common stock			$ 8,100,000
$150.0 Million ATM | At The Market Equity Program
Equity [Line Items]
Number of sales agents | Agent				4
$250.0 Million ATM | At The Market Equity Program
Equity [Line Items]
Number of sales agents | Agent		5