Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
ASSETS
Operating real estate	$ 1,931,698	$ 1,919,015
Construction in progress	195,736	67,389
Held for development	9,390	9,013
Total Real estate, at cost	2,136,824	1,995,417
Accumulated depreciation	(361,424)	(318,581)
Net real estate	1,775,400	1,676,836
Cash and cash equivalents	59,357	48,987	42,479
Restricted cash	10,994	9,124
Accounts receivable, net	6,727	7,295
Deferred rent receivables, net	35,883	32,531
Other assets, net	53,401	57,670
TOTAL ASSETS	1,941,762	1,832,443
LIABILITIES AND EQUITY
Secured notes payable	812,811	952,174
Unsecured notes payable	250,000	0
Unsecured line of credit	0	93,000
Accounts payable and accrued expenses	50,861	37,063
Security deposits payable	5,521	5,163
Other liabilities and deferred credits	55,993	58,465
Total liabilities	1,175,186	1,145,865
Commitments and contingencies (Note 13)
American Assets Trust, Inc. stockholders' equity
Common stock, $0.01 par value, 490,000,000 shares authorized, 43,701,669 and 40,512,563 shares issued and outstanding at December 31, 2014 and 2013, respectively	437	405
Additional paid-in capital	795,065	692,196
Accumulated dividends in excess of net income	(60,291)	(44,090)
Accumulated other comprehensive income	92	0
Total American Assets Trust, Inc. stockholders' equity	735,303	648,511
Noncontrolling interests	31,273	38,067
Total equity	766,576	686,578	685,729
TOTAL LIABILITIES AND EQUITY	1,941,762	1,832,443
American Assets Trust, L.P.
ASSETS
Operating real estate	1,931,698	1,919,015
Construction in progress	195,736	67,389
Held for development	9,390	9,013
Total Real estate, at cost	2,136,824	1,995,417
Accumulated depreciation	(361,424)	(318,581)
Net real estate	1,775,400	1,676,836
Cash and cash equivalents	59,357	48,987	42,479
Restricted cash	10,994	9,124
Accounts receivable, net	6,727	7,295
Deferred rent receivables, net	35,883	32,531
Other assets, net	53,401	57,670
TOTAL ASSETS	1,941,762	1,832,443
LIABILITIES AND EQUITY
Secured notes payable	812,811	952,174
Unsecured notes payable	250,000	0
Unsecured line of credit	0	93,000
Accounts payable and accrued expenses	50,861	37,063
Security deposits payable	5,521	5,163
Other liabilities and deferred credits	55,993	58,465
Total liabilities	1,175,186	1,145,865
American Assets Trust, Inc. stockholders' equity
Accumulated other comprehensive income	130	0
TOTAL LIABILITIES AND EQUITY	1,941,762	1,832,443
Partners' Capital [Abstract]
Limited partners' capital, 17,905,257 and 17,917,109 units issued and outstanding as of December 31, 2014 and December 31, 2013, respectively	31,235	38,067
General partners' capital, 43,701,669 and 40,512,563 units issued and outstanding as of December 31, 2014 and December 31, 2013, respectively	735,211	648,511
Total capital	$ 766,576	$ 686,578	$ 685,729