Consolidated Balance Sheets (Unaudited) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
ASSETS
Operating real estate	$ 1,938,663	$ 1,931,698
Construction in progress	232,597	195,736
Held for development	9,413	9,390
Total Real estate, at cost	2,180,673	2,136,824
Accumulated depreciation	(373,794)	(361,424)
Net real estate	1,806,879	1,775,400
Cash and cash equivalents	54,639	59,357
Restricted cash	10,252	10,994
Accounts receivable, net	5,772	6,727
Deferred rent receivables, net	36,467	35,883
Other assets, net	52,140	53,401
TOTAL ASSETS	1,966,149	1,941,762
LIABILITIES AND EQUITY
Secured notes payable	711,809	812,811
Unsecured notes payable	350,000	250,000
Unsecured line of credit	20,000	0
Accounts payable and accrued expenses	55,045	50,861
Security deposits payable	5,874	5,521
Other liabilities and deferred credits, net	55,867	55,993
Total liabilities	1,198,595	1,175,186
Commitments and contingencies (Note 11)
American Assets Trust, Inc. stockholders’ equity
Common stock, $0.01 par value, 490,000,000 shares authorized, 43,821,165 and 43,701,669 shares issued and outstanding at March 31, 2015 and December 31, 2014, respectively	438	437
Additional paid-in capital	800,081	795,065
Accumulated dividends in excess of net income	(62,409)	(60,291)
Accumulated other comprehensive (loss) income	(618)	92
Total American Assets Trust, Inc. stockholders’ equity	737,492	735,303
Noncontrolling interests	30,062	31,273
Total equity	767,554	766,576
TOTAL LIABILITIES AND EQUITY	1,966,149	1,941,762
American Assets Trust, L.P.
ASSETS
Operating real estate	1,938,663	1,931,698
Construction in progress	232,597	195,736
Held for development	9,413	9,390
Total Real estate, at cost	2,180,673	2,136,824
Accumulated depreciation	(373,794)	(361,424)
Net real estate	1,806,879	1,775,400
Cash and cash equivalents	54,639	59,357
Restricted cash	10,252	10,994
Accounts receivable, net	5,772	6,727
Deferred rent receivables, net	36,467	35,883
Other assets, net	52,140	53,401
TOTAL ASSETS	1,966,149	1,941,762
LIABILITIES AND EQUITY
Secured notes payable	711,809	812,811
Unsecured notes payable	350,000	250,000
Unsecured line of credit	20,000	0
Accounts payable and accrued expenses	55,045	50,861
Security deposits payable	5,874	5,521
Other liabilities and deferred credits, net	55,867	55,993
Total liabilities	1,198,595	1,175,186
American Assets Trust, Inc. stockholders’ equity
Accumulated other comprehensive (loss) income	(871)	130
TOTAL LIABILITIES AND EQUITY	1,966,149	1,941,762
Partners' Capital [Abstract]
Limited Partners' Capital Account	30,315	31,235
General Partners' Capital Account	738,110	735,211
Partners' Capital	$ 767,554	$ 766,576