Consolidated Statements of Comprehensive Income (Unaudited) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
REVENUE:
Rental income	$ 62,753	$ 60,482
Other property income	3,282us-gaap_OtherRealEstateRevenue	3,498us-gaap_OtherRealEstateRevenue
Total revenue	66,035us-gaap_Revenues	63,980us-gaap_Revenues
EXPENSES:
Rental expenses	16,620us-gaap_CostOfRealEstateRevenue	16,620us-gaap_CostOfRealEstateRevenue
Real estate taxes	6,048us-gaap_RealEstateTaxExpense	6,026us-gaap_RealEstateTaxExpense
General and administrative	5,016us-gaap_GeneralAndAdministrativeExpense	4,612us-gaap_GeneralAndAdministrativeExpense
Depreciation and amortization	15,107us-gaap_DepreciationAndAmortization	16,341us-gaap_DepreciationAndAmortization
Total operating expenses	42,791us-gaap_OperatingExpenses	43,599us-gaap_OperatingExpenses
OPERATING INCOME	23,244us-gaap_OperatingIncomeLoss	20,381us-gaap_OperatingIncomeLoss
Interest expense	(11,795)	(13,632)
Other income (expense), net	(70)us-gaap_OtherNonoperatingIncomeExpense	(91)us-gaap_OtherNonoperatingIncomeExpense
NET INCOME	11,379us-gaap_ProfitLoss	6,658us-gaap_ProfitLoss
Net income attributable to restricted shares	(43)	(70)
Net income attributable to unitholders in the Operating Partnership	(3,309)	(1,986)
NET INCOME ATTRIBUTABLE TO AMERICAN ASSETS TRUST, INC. STOCKHOLDERS	8,027us-gaap_NetIncomeLoss	4,602us-gaap_NetIncomeLoss
EARNINGS PER COMMON SHARE
Earnings per common share, basic	$ 0.18us-gaap_EarningsPerShareBasic	$ 0.11us-gaap_EarningsPerShareBasic
Weighted average shares of common stock outstanding-basic	43,419,762	40,582,792
EARNINGS PER COMMON SHARE, DILUTED
Earnings per common share, diluted	$ 0.18us-gaap_EarningsPerShareDiluted	$ 0.11us-gaap_EarningsPerShareDiluted
Weighted average shares of common stock outstanding-diluted	61,321,447	58,492,473
Dividends declared per common share	$ 0.2325	$ 0.22
COMPREHENSIVE INCOME
Net income	11,379us-gaap_ProfitLoss	6,658us-gaap_ProfitLoss
Other comprehensive loss - unrealized loss on swap derivative during the period	(943)	(746)
Reclassification of amortization of forward-starting swap included in interest expense	(58)	0
Comprehensive income	10,378	5,912
Comprehensive income attributable to non-controlling interest	(3,018)	(1,761)
Comprehensive income attributable to American Assets Trust, Inc.	7,360us-gaap_ComprehensiveIncomeNetOfTax	4,151us-gaap_ComprehensiveIncomeNetOfTax
American Assets Trust, L.P.
REVENUE:
Rental income	62,753	60,482
Other property income	3,282	3,498
Total revenue	66,035	63,980
EXPENSES:
Rental expenses	16,620	16,620
Real estate taxes	6,048	6,026
General and administrative	5,016	4,612
Depreciation and amortization	15,107	16,341
Total operating expenses	42,791	43,599
OPERATING INCOME	23,244	20,381
Interest expense	(11,795)	(13,632)
Other income (expense), net	(70)	(91)
NET INCOME	11,379	6,658
Net income attributable to restricted shares	(43)	(70)
NET INCOME ATTRIBUTABLE TO AMERICAN ASSETS TRUST, INC. STOCKHOLDERS	11,336	6,588
DISTRIBUTIONS PER UNIT	$ 0.2325	$ 0.22
EARNINGS PER COMMON SHARE
Earnings per common share, basic	$ 0.18	$ 0.11
Weighted average shares of common stock outstanding-basic	61,321,447	58,492,473
EARNINGS PER COMMON SHARE, DILUTED
Earnings per common share, diluted	$ 0.18	$ 0.11
Weighted average shares of common stock outstanding-diluted	61,321,447	58,492,473
COMPREHENSIVE INCOME
Net income	11,379	6,658
Other comprehensive loss - unrealized loss on swap derivative during the period	(943)	(746)
Reclassification of amortization of forward-starting swap included in interest expense	(58)	0
Comprehensive income	10,378	5,912
Limited Partner \| American Assets Trust, L.P.
EXPENSES:
NET INCOME	3,309
COMPREHENSIVE INCOME
Net income	3,309
Comprehensive income attributable to American Assets Trust, Inc.	(3,018)	(1,761)
General Partner \| American Assets Trust, L.P.
EXPENSES:
NET INCOME	8,070
COMPREHENSIVE INCOME
Net income	8,070
Comprehensive income attributable to American Assets Trust, Inc.	$ 7,360	$ 4,151

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