American Assets Trust (AAT) 10-Q 1 May 15 2015 Q1 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	3 Months Ended
	Mar. 31, 2015	1-May-15
Document Information [Line Items]
Document Type	10-Q
Amendment Flag	FALSE
Document Period End Date	31-Mar-15
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	Q1
Trading Symbol	AAT
Entity Registrant Name	AMERICAN ASSETS TRUST, INC.
Entity Central Index Key	1500217
Current Fiscal Year End Date	-19
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		43,821,165
American Assets Trust, L.P.
Document Information [Line Items]
Document Type	10-Q
Amendment Flag	FALSE
Document Period End Date	31-Mar-15
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	Q1
Entity Registrant Name	AMERICAN ASSETS TRUST, L.P..
Entity Central Index Key	1509570
Current Fiscal Year End Date	-19
Entity Filer Category	Non-accelerated Filer

Consolidated_Balance_Sheets_Un

Consolidated Balance Sheets (Unaudited) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
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

Consolidated_Balance_Sheets_Un1

Consolidated Balance Sheets (Unaudited) (Parenthetical) (USD $)	Mar. 31, 2015	Dec. 31, 2014
Common Shares
Common stock, par value	$0.01	$0.01
Common stock, shares authorized	490,000,000	490,000,000
Common stock, shares outstanding	43,821,165	43,701,669
Common stock, shares issued	43,821,165	43,701,669
American Assets Trust, L.P.
Limited Partners' Capital Account, Units Issued	17,899,516	17,905,257
Limited Partners' Capital Account, Units Outstanding	17,899,516	17,905,257
General Partners' Capital Account, Units Issued	43,821,165	43,701,669
General Partners' Capital Account, Units Outstanding	43,821,165	43,701,669

Consolidated_Statements_of_Com

Consolidated Statements of Comprehensive Income (Unaudited) (USD $)	3 Months Ended
In Thousands, except Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
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 unitholders in the Operating Partnership	-3,309	-1,986
NET INCOME ATTRIBUTABLE TO AMERICAN ASSETS TRUST, INC. STOCKHOLDERS	8,027	4,602
EARNINGS PER COMMON SHARE
Earnings per common share, basic	$0.18	$0.11
Weighted average shares of common stock outstanding-basic	43,419,762	40,582,792
EARNINGS PER COMMON SHARE, DILUTED
Earnings per common share, diluted	$0.18	$0.11
Weighted average shares of common stock outstanding-diluted	61,321,447	58,492,473
Dividends declared per common share	$0.23	$0.22
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
Comprehensive income attributable to non-controlling interest	-3,018	-1,761
Comprehensive income attributable to American Assets Trust, Inc.	7,360	4,151
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	$0.23	$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

Consolidated_Statement_of_Equi

Consolidated Statement of Equity (Unaudited) (USD $)	Total	Common Shares	Additional Paid-in Capital	Accumulated Dividends in Excess of Net Income	Accumulated Other Comprehensive Income (Loss)	Noncontrolling Interests - Unitholders in the Operating Partnership	American Assets Trust, L.P.	American Assets Trust, L.P.	Limited Partner	General Partner	Accumulated Other Comprehensive Income (Loss)
In Thousands, except Share data, unless otherwise specified	USD ($)	USD ($)	USD ($)	USD ($)	USD ($)	USD ($)	USD ($)	Common Shares	American Assets Trust, L.P.	American Assets Trust, L.P.	American Assets Trust, L.P.
									USD ($)	USD ($)	USD ($)
Beginning Partners' Capital Account at Dec. 31, 2014							$766,576		$31,235	$735,211	$130
Beginning Balance at Dec. 31, 2014	766,576	437	795,065	-60,291	92	31,273
Beginning Balance (in shares) at Dec. 31, 2014		43,701,669
Beginning Partners' Capital Account, Units at Dec. 31, 2014									17,905,257	43,701,669
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	11,379			8,070		3,309	11,379		3,309	8,070
Common shares issued (in shares)		253,800
Common shares issued	10,272	2	10,270
Conversion of operating partnership units (in shares)		5,741						5,741
Conversion of operating partnership units	0		67			-67
Dividends declared and paid	-14,350			-10,188		-4,162
Stock-based compensation	890		890
Shares withheld for employee taxes (in shares)		-140,045								-140,045
Shares withheld for employee taxes	-6,212	-1	-6,211				-6,212			-6,212
Other comprehensive loss - change in value of interest rate swap	-943				-669	-274	-943				-943
Reclassification of amortization of forward-starting swap included in interest expense	-58				-41	-17	-58				-58
Increase (Decrease) in Partners' Capital [Roll Forward]
Net income	11,379			8,070		3,309	11,379		3,309	8,070
Partners' Capital Account, Units, Contributed										253,800
Partners' Capital Account, Contributions							10,272			10,272
Partners' Capital Account, Units, Converted									-5,741	5,741
Partners' Capital Account, Exchanges and Conversions									-67	67
Shares withheld for employee taxes (in shares)		-140,045								-140,045
Shares withheld for employee taxes	-6,212	-1	-6,211				-6,212			-6,212
Other comprehensive loss - unrealized loss on swap derivative during the period	-943				-669	-274	-943				-943
Reclassification of amortization of forward-starting swap included in interest expense	-58				-41	-17	-58				-58
Partners' Capital Account, Distributions							-14,350		-4,162	-10,188
Partners' Capital Account, Unit-based Compensation							890			890
Ending Partners' Capital Account at Mar. 31, 2015							767,554		30,315	738,110	-871
Ending Balance at Mar. 31, 2015	$767,554	$438	$800,081	($62,409)	($618)	$30,062
Ending Balance (in shares) at Mar. 31, 2015		43,821,165
Ending Partners' Capital Account, Units at Mar. 31, 2015									17,899,516	43,821,165

Consolidated_Statements_of_Cas

Consolidated Statements of Cash Flows (Unaudited) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
OPERATING ACTIVITIES
Net income	$11,379	$6,658
Adjustments to reconcile net income to net cash provided by operating activities:
Deferred rent revenue and amortization of lease intangibles	-1,353	-1,545
Depreciation and amortization	15,107	16,341
Amortization of debt issuance costs and debt fair value adjustments	1,045	1,015
Stock-based compensation expense	890	519
Other noncash interest expense	-58	0
Other, net	180	-362
Changes in operating assets and liabilities
Change in restricted cash	943	-1,141
Change in accounts receivable	874	1,022
Change in other assets	-1,143	-392
Change in accounts payable and accrued expenses	4,145	4,705
Change in security deposits payable	353	58
Change in other liabilities and deferred credits	148	1,115
Net cash provided by operating activities	32,510	27,993
INVESTING ACTIVITIES
Capital expenditures	-44,125	-30,300
Change in restricted cash	-201	-303
Leasing commissions	-843	-996
Net cash used in investing activities	-45,169	-31,599
FINANCING ACTIVITIES
Repayment of secured notes payable	-101,729	-405
Proceeds from term loan	0	100,000
Proceeds from unsecured line of credit	20,000	0
Repayment of unsecured line of credit	0	-93,000
Proceeds from issuance of unsecured notes payable	100,000	0
Debt issuance costs	-40	-1,957
Proceeds from issuance of common stock, net	10,272	46,926
Dividends paid to common stock and unitholders	-14,350	-13,140
Shares withheld for employee taxes	-6,212	-4,319
Net cash provided by financing activities	7,941	34,105
Net (decrease) increase in cash and cash equivalents	-4,718	30,499
Cash and cash equivalents, beginning of period	59,357	48,987
Cash and cash equivalents, end of period	54,639	79,486
American Assets Trust, L.P.
OPERATING ACTIVITIES
Net income	11,379	6,658
Adjustments to reconcile net income to net cash provided by operating activities:
Deferred rent revenue and amortization of lease intangibles	-1,353	-1,545
Depreciation and amortization	15,107	16,341
Amortization of debt issuance costs and debt fair value adjustments	1,045	1,015
Stock-based compensation expense	890	519
Other noncash interest expense	-58	0
Other, net	180	-362
Changes in operating assets and liabilities
Change in restricted cash	943	-1,141
Change in accounts receivable	874	1,022
Change in other assets	-1,143	-392
Change in accounts payable and accrued expenses	4,145	4,705
Change in security deposits payable	353	58
Change in other liabilities and deferred credits	148	1,115
Net cash provided by operating activities	32,510	27,993
INVESTING ACTIVITIES
Capital expenditures	-44,125	-30,300
Change in restricted cash	-201	-303
Leasing commissions	-843	-996
Net cash used in investing activities	-45,169	-31,599
FINANCING ACTIVITIES
Repayment of secured notes payable	-101,729	-405
Proceeds from term loan	0	100,000
Proceeds from unsecured line of credit	20,000	0
Repayment of unsecured line of credit	0	-93,000
Proceeds from issuance of unsecured notes payable	100,000	0
Debt issuance costs	-40	-1,957
Proceeds from issuance of common stock, net	10,272	46,926
Dividends paid to common stock and unitholders	-14,350	-13,140
Shares withheld for employee taxes	-6,212	-4,319
Net cash provided by financing activities	7,941	34,105
Net (decrease) increase in cash and cash equivalents	-4,718	30,499
Cash and cash equivalents, beginning of period	59,357	48,987
Cash and cash equivalents, end of period	$54,639	$79,486

SUMMARY_OF_SIGNIFICANT_ACCOUNT

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	3 Months Ended
	Mar. 31, 2015
Accounting Policies [Abstract]
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
	Business and Organization
	American Assets Trust, Inc. (which may be referred to in these financial statements as the “Company,” “we,” “us,” or “our”) is a Maryland corporation formed on July 16, 2010 that did not have any operating activity until the consummation of our initial public offering on January 19, 2011. The Company is the sole general partner of American Assets Trust, L.P., a Maryland limited partnership formed on July 16, 2010 (the “Operating Partnership”). The Company’s operations are carried on through our Operating Partnership and its subsidiaries, including our taxable real estate investment trust ("REIT") subsidiary ("TRS"). Since the formation of our Operating Partnership, the Company has controlled our Operating Partnership as its general partner and has consolidated its assets, liabilities and results of operations.
	We are a full service vertically integrated and self-administered REIT with approximately 127 employees providing substantial in-house expertise in asset management, property management, property development, leasing, tenant improvement construction, acquisitions, repositioning, redevelopment and financing.
	As of March 31, 2015, we owned or had a controlling interest in 23 office, retail, multifamily and mixed-use operating properties, the operations of which we consolidate. Additionally, as of March 31, 2015, we owned land at five of our properties that we classify as held for development and/or construction in progress. A summary of the properties owned by us is as follows:
	Retail
	Carmel Country Plaza	Del Monte Center
	Carmel Mountain Plaza	Geary Marketplace
	South Bay Marketplace	The Shops at Kalakaua
	Rancho Carmel Plaza	Waikele Center
	Lomas Santa Fe Plaza	Alamo Quarry Market
	Solana Beach Towne Centre
	Office
	Torrey Reserve Campus	Lloyd District Portfolio
	Solana Beach Corporate Centre	City Center Bellevue
	The Landmark at One Market
	One Beach Street
	First & Main
	Multifamily
	Loma Palisades
	Imperial Beach Gardens
	Mariner's Point
	Santa Fe Park RV Resort
	Mixed-Use
	Waikiki Beach Walk Retail and Embassy Suites™ Hotel
	Held for Development and/or Construction in Progress
	Solana Beach Corporate Centre – Land
	Solana Beach – Highway 101 – Land
	Torrey Point (formerly Sorrento Pointe) – Land
	Torrey Reserve – Land
	Lloyd District Portfolio – Land
	Basis of Presentation
	Our consolidated financial statements include the accounts of the Company, our Operating Partnership and our subsidiaries. The equity interests of other investors in our Operating Partnership are reflected as noncontrolling interests.
	All significant intercompany transactions and balances are eliminated in consolidation.
	The accompanying consolidated financial statements of the Company and the Operating Partnership have been prepared in accordance with the rules applicable to Form 10-Q and include all information and footnotes required for interim financial statement presentation, but do not include all disclosures required under accounting principles generally accepted in the United States (“GAAP”) for annual financial statements. In the opinion of management, all adjustments (consisting of normal recurring adjustments, except as otherwise noted) considered necessary for a fair presentation have been included. These financial statements should be read in conjunction with the audited consolidated financial statements and notes therein included in the Company's and Operating Partnership's annual report on Form 10-K for the year ended December 31, 2014.
	The preparation of financial statements in conformity with GAAP requires us to make estimates and assumptions that in certain circumstances affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities, and revenues and expenses. These estimates are prepared using our best judgment, after considering past, current and expected events and economic conditions. Actual results could differ from these estimates.
	Any reference to the number of properties and square footage are unaudited and outside the scope of our independent registered public accounting firm’s review of our financial statements in accordance with the standards of the United States Public Company Accounting Oversight Board.
	Consolidated Statements of Cash Flows—Supplemental Disclosures
	The following table provides supplemental disclosures related to the Consolidated Statements of Cash Flows (in thousands):
		Three Months Ended March 31,
		2015			2014
	Supplemental cash flow information
	Total interest costs incurred	$	14,128		$	14,467
	Interest capitalized	$	2,333		$	835
	Interest expense	$	11,795		$	13,632
	Cash paid for interest, net of amounts capitalized	$	10,459		$	12,724
	Cash paid for income taxes	$	50		$	—
	Supplemental schedule of noncash investing and financing activities
	Accounts payable and accrued liabilities for construction in progress	$	205		$	(890	)
	Accrued leasing commissions	$	(166	)	$	(630	)
	Significant Accounting Policies
	We describe our significant accounting policies in Note 1 to the consolidated financial statements in Item 8 of our Annual Report on Form 10-K for the year ended December 31, 2014. There have been no changes to our significant accounting policies during the three months ended March 31, 2015.
	Segment Information
	Segment information is prepared on the same basis that our management reviews information for operational decision-making purposes. We operate in four business segments: the acquisition, redevelopment, ownership and management of retail real estate, office real estate, multifamily real estate and mixed-use real estate. The products for our retail segment primarily include rental of retail space and other tenant services, including tenant reimbursements, parking and storage space rental. The products for our office segment primarily include rental of office space and other tenant services, including tenant reimbursements, parking and storage space rental. The products for our multifamily segment include rental of apartments and other tenant services. The products of our mixed-use segment include rental of retail space and other tenant services, including tenant reimbursements, parking and storage space rental and operation of a 369-room all-suite hotel.
	Reclassification
	Certain amounts in the consolidated financial statements for prior periods have been reclassified to conform to current presentations.
	Recent Accounting Pronouncements
	In April 2014, the FASB issued Accounting Standards Update (ASU) 2014-08, Presentation of Financial Statements (Topic 205) and Property, Plant, and Equipment (Topic 360): Reporting Discontinued Operations and Disclosures of Disposals of Components of an Entity. ASU 2014-08 revises the definition of a discontinued operation to a disposal, sale or held-for-sale component or group of components that represents a strategic shift that will have a major effect on an entity's operations and financial results. This pronouncement is effective in 2015, however, calendar year-end companies may early adopt during the first quarter of 2014. We have chosen to early adopt this pronouncement and it became effective for us in the first quarter of 2014. This pronouncement did not have a significant impact on our consolidated financial statements.
	In May 2014, the FASB issued Update No. 2014-09, Revenue from Contracts with Customers. Update No. 2014-09 establishes that companies may recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. This pronouncement is effective for annual reporting periods beginning after December 15, 2016, including interim reporting periods within that reporting period; early adoption is not permitted. We are in the process of evaluating the impact this pronouncement will have on our consolidated financial statements.
	In February 2015, the FASB issued an ASU that requires reporting entities to evaluate whether they should consolidate certain legal entities. The ASU modifies the evaluation of whether limited partnerships and similar legal entities are VIEs or voting interest entities and eliminates the presumption that a general partner should consolidate a limited partnership. This affects the consolidation analysis of reporting entities that are involved with VIEs, particularly those that have fee arrangements and related party relationships. The ASU is effective for fiscal years, and for interim periods within those fiscal years, beginning after December 15, 2015, with early adoption permitted. A reporting entity may apply the amendments in the ASU using: (i) a modified retrospective approach by recording a cumulative-effect adjustment to equity as of the beginning of the fiscal year of adoption; or (ii) by applying the amendments retrospectively. We are in the process of evaluating the impact of adopting this ASU and currently do not expect that the adoption will have a material impact on our consolidated financial statements.
	In April 2015, the FASB issued an ASU that requires reporting entities to present debt issuance cost related to a note as a direct deduction from the face amount of that note presented in the balance sheet. The ASU requires the amortization of debt issuance costs presented as interest expense. The ASU is effective for fiscal years, and for interim periods within those fiscal years, beginning after December 15, 2015, with early adoption permitted. A reporting entity may apply the amendments in the ASU retrospectively to all prior periods. We do not expect that the adoption of this ASU will have a material impact on our consolidated financial statements.

ACQUIRED_INPLACE_LEASES_AND_AB

ACQUIRED IN-PLACE LEASES AND ABOVE/BELOW MARKET LEASES	3 Months Ended
	Mar. 31, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
ACQUIRED IN-PLACE LEASES AND ABOVE/BELOW MARKET LEASES	ACQUIRED IN-PLACE LEASES AND ABOVE/BELOW MARKET LEASES
	The following summarizes our acquired lease intangibles and leasing costs, which are included in other assets and other liabilities and deferred credits, as of March 31, 2015 and December 31, 2014 (in thousands):
		March 31, 2015			December 31, 2014
	In-place leases	$	53,383		$	53,967
	Accumulated amortization	(36,001		)	(35,336		)
	Above market leases	22,291			22,500
	Accumulated amortization	(17,644		)	(17,397		)
	Acquired lease intangible assets, net	$	22,029		$	23,734
	Below market leases	$	70,013		$	70,013
	Accumulated accretion	(28,344		)	(27,161		)
	Acquired lease intangible liabilities, net	$	41,669		$	42,852

FAIR_VALUE_OF_FINANCIAL_INSTRU

FAIR VALUE OF FINANCIAL INSTRUMENTS	3 Months Ended
	Mar. 31, 2015
Fair Value Disclosures [Abstract]
FAIR VALUE OF FINANCIAL INSTRUMENTS	FAIR VALUE OF FINANCIAL INSTRUMENTS
	A fair value measurement is based on the assumptions that market participants would use in pricing an asset or liability. The hierarchy for inputs used in measuring fair value is as follows:
	1	Level 1 Inputs—quoted prices in active markets for identical assets or liabilities
	2	Level 2 Inputs—observable inputs other than quoted prices in active markets for identical assets and liabilities
	3	Level 3 Inputs—unobservable inputs
	Except as disclosed below, the carrying amounts of our financial instruments approximate their fair value. In certain cases, the inputs used to measure fair value may fall into different levels of the fair value hierarchy. In such cases, for disclosure purposes, the level within which the fair value measurement is categorized is based on the lowest level input that is significant to the fair value measurement.
	We measure the fair value of our deferred compensation liability, which is included in other liabilities and deferred credits on the consolidated balance sheet, on a recurring basis using Level 2 inputs. We measure the fair value of this liability based on prices provided by independent market participants that are based on observable inputs using market-based valuation techniques.
	The fair value of the interest rate swap agreement on our term loan of $100 million is based on the estimated amounts we would receive or pay to terminate the contract at the reporting date and are determined using interest rate pricing models and interest rate related observable inputs. The fair value of our swap at March 31, 2015 was a liability of $2.4 million and is included in "other liabilities and deferred credits" on our consolidated balance sheets. For the three months ended March 31, 2015, the change in valuation on our interest rate swap was a decrease of $0.9 million. The effective portion of changes in the fair value of the derivatives that are designated as cash flow hedges are being recorded in accumulated other comprehensive loss and will be subsequently reclassified into earnings during the period in which the hedged forecasted transaction affects earnings.
	We incorporate credit valuation adjustments to appropriately reflect both our own non-performance risk and the respective counterparty’s non-performance risk in the fair value measurements. In adjusting the fair value of our derivative contract for the effect of non-performance risk, we considered the impact of netting and any applicable credit enhancements, such as collateral postings, thresholds, mutual puts, and guarantees.
	Although we have determined that the majority of the inputs used to value our derivatives fall within Level 2 of the fair value hierarchy, the credit valuation adjustments associated with its derivatives utilize Level 3 inputs, such as estimates of current credit spreads to evaluate the likelihood of default by itself and its counterparties. However, as of March 31, 2015 we have assessed the significance of the impact of the credit valuation adjustments on the overall valuation of our derivative position and have determined that the credit valuation adjustments are not significant to the overall valuation of our derivative. As a result, we have determined that our derivative valuation in its entirety is classified in Level 2 of the fair value hierarchy.
	A summary of our financial liabilities that are measured at fair value on a recurring basis, by level within the fair value hierarchy is as follows (in thousands):
		March 31, 2015											December 31, 2014
		Level 1		Level 2			Level 3			Total			Level 1		Level 2		Level 3		Total
	Deferred compensation liability	$	—	$	1,042		$	—		$	1,042		$	—	$	981	$	—	$	981
	Interest rate swap	$	—	$	2,391		$	—		$	2,391		$	—	$	1,448	$	—	$	1,448
	The fair value of our secured notes payable and unsecured senior guaranteed notes are sensitive to fluctuations in interest rates. Discounted cash flow analysis using observable market interest rates (Level 2) is generally used to estimate the fair value of our secured notes payable, using rates ranging from 3.4% to 5.5%.
	Considerable judgment is necessary to estimate the fair value of financial instruments. The estimates of fair value presented herein are not necessarily indicative of the amounts that could be realized upon disposition of the financial instruments. The carrying values of our revolving line of credit and term loan set forth below are deemed to be at fair value since the outstanding debt is directly tied to monthly LIBOR contracts. A summary of the carrying amount and fair value of our secured financial instruments, all of which are based on Level 2 inputs, is as follows (in thousands):
		March 31, 2015							December 31, 2014
		Carrying Value			Fair Value				Carrying Value			Fair Value
	Secured notes payable	$	711,809		$	750,138			$	812,811		$	850,475
	Unsecured term loan	$	100,000		$	100,000			$	100,000		$	100,000
	Unsecured senior guaranteed notes	$	250,000		$	260,019			$	150,000		$	154,560
	Unsecured line of credit	$	20,000		$	20,000			$	—		$	—

DERIVATIVE_AND_HEDGING

DERIVATIVE AND HEDGING	3 Months Ended
	Mar. 31, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
DERIVATIVE AND HEDGING ACTIVITIES	DERIVATIVE AND HEDGING ACTIVITIES
	Our objectives in using interest rate derivatives are to add stability to interest expense and to manage our exposure to interest rate movements.  To accomplish these objectives, we primarily use interest rate swaps as part of our interest rate risk management strategy.  Interest rate swaps designated as cash flow hedges involve the receipt of variable-rate amounts from a counterparty in exchange for us making fixed-rate payments over the life of the agreements without exchange of the underlying notional amount.
	Concurrent with the closing of our amended and restated credit facility, we entered into an interest rate swap agreement that is intended to fix the interest rate associated with the term loan at approximately 3.08% through its maturity date and extension options, subject to adjustments based on our consolidated leverage ratio. The following is a summary of the terms of the interest rate swap as of March 31, 2015 (dollars in thousands):
	Swap Counterparty	Notional Amount		Effective Date	Maturity Date	Fair Value
	Bank of America, N.A.	$	100,000	1/9/14	1/9/19	$	2,391
	The effective portion of changes in the fair value of the derivatives that are designated as cash flow hedges are being recorded in accumulated other comprehensive income and will be subsequently reclassified into earnings during the period in which the hedged forecasted transaction affects earnings.
	The valuation of these instruments is determined using widely accepted valuation techniques including discounted cash flow analysis on the expected cash flows of the derivative.  This analysis reflects the contractual terms of the derivative, including the period to maturity, and uses observable market-based inputs, including interest rate curves, and implied volatilities.  The fair value of the interest rate swap is determined using the market standard methodology of netting the discounted future fixed cash receipts (or payments) and the discounted expected variable cash payments (or receipts).  The variable cash payments (or receipts) are based on an expectation of future interest rates (forward curves) derived from observable market interest rate curves.

OTHER_ASSETS

OTHER ASSETS	3 Months Ended
	Mar. 31, 2015
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
OTHER ASSETS	OTHER ASSETS
	Other assets consist of the following (in thousands):
		March 31, 2015		December 31, 2014
	Leasing commissions, net of accumulated amortization of $21,392 and $20,659 respectively	$	19,197	$	19,484
	Acquired above market leases, net	4,647		5,103
	Acquired in-place leases, net	17,382		18,631
	Lease incentives, net of accumulated amortization of $3,053 and $2,960, respectively	647		740
	Other intangible assets, net of accumulated amortization of $1,612 and $1,590, respectively	411		453
	Debt issuance costs, net of accumulated amortization of $4,416 and $4,147, respectively	5,083		5,361
	Prepaid expenses and other	4,773		3,629
	Total other assets	$	52,140	$	53,401

OTHER_LIABILITIES_AND_DEFERRED

OTHER LIABILITIES AND DEFERRED CREDITS	3 Months Ended
	Mar. 31, 2015
Other Liabilities Disclosure [Abstract]
OTHER LIABILITIES AND DEFERRED CREDITS	OTHER LIABILITIES AND DEFERRED CREDITS
	Other liabilities and deferred credits consist of the following (in thousands):
		March 31, 2015		December 31, 2014
	Acquired below market leases, net	$	41,669	$	42,852
	Prepaid rent and deferred revenue	7,538		7,288
	Interest rate swap liability	2,391		1,448
	Deferred rent expense and lease intangible	511		584
	Deferred compensation	1,042		981
	Deferred tax liability	219		219
	Straight-line rent liability	2,410		2,533
	Other liabilities	87		88
	Total other liabilities and deferred credits, net	$	55,867	$	55,993
	Straight-line rent liability relates to leases which have rental payments that decrease over time or one-time upfront payments for which the rental revenue is deferred and recognized on a straight-line basis.

DEBT

DEBT	3 Months Ended
	Mar. 31, 2015
Debt Disclosure [Abstract]
DEBT	DEBT
	Debt of American Assets Trust, Inc.
	American Assets Trust, Inc. does not hold any indebtedness. All debt is held directly or indirectly by the Operating Partnership; however, American Assets Trust, Inc. has guaranteed the Operating Partnership's obligations under the (i) amended and restated credit facility, (ii) term loan and (iii) senior guaranteed notes. Additionally, American Assets Trust, Inc. has provided carve-out guarantees on certain property-level debt.
	Debt of American Assets Trust, L.P.
	Secured notes payable
	The following is a summary of our total secured notes payable outstanding as of March 31, 2015 and December 31, 2014 (in thousands):
		Principal Balance as of						Stated Interest Rate		Stated Maturity Date
	Description of Debt	March 31, 2015			December 31, 2014			as of March 31, 2015
	The Shops at Kalakaua (1)(2)	$	—		$	19,000		—		May 1, 2015
	The Landmark at One Market (1)(3)	133,000			133,000			5.61	%	July 5, 2015
	Del Monte Center (1)(4)	—			82,300			—		July 8, 2015
	First & Main (1)	84,500			84,500			3.97	%	July 1, 2016
	Imperial Beach Gardens (1)	20,000			20,000			6.16	%	September 1, 2016
	Mariner’s Point (1)	7,700			7,700			6.09	%	September 1, 2016
	South Bay Marketplace (1)	23,000			23,000			5.48	%	February 10, 2017
	Waikiki Beach Walk—Retail (1)	130,310			130,310			5.39	%	July 1, 2017
	Solana Beach Corporate Centre III-IV (5)	36,257			36,376			6.39	%	August 1, 2017
	Loma Palisades (1)	73,744			73,744			6.09	%	July 1, 2018
	One Beach Street (1)	21,900			21,900			3.94	%	April 1, 2019
	Torrey Reserve—North Court (5)	20,995			21,075			7.22	%	June 1, 2019
	Torrey Reserve—VCI, VCII, VCIII (5)	7,074			7,101			6.36	%	June 1, 2020
	Solana Beach Corporate Centre I-II (5)	11,255			11,302			5.91	%	June 1, 2020
	Solana Beach Towne Centre (5)	37,518			37,675			5.91	%	June 1, 2020
	City Center Bellevue (1)	111,000			111,000			3.98	%	November 1, 2022
		718,253			819,983
	Unamortized fair value adjustment	(6,444		)	(7,172		)
	Total Secured Notes Payable Outstanding	$	711,809		$	812,811
	-1	Interest only.
	-2	Loan repaid in full, without premium or penalty, on February 2, 2015.
	-3	Loan repaid in full, without premium or penalty, on April 6, 2015.
	-4	Loan repaid in full, without premium or penalty, on February 6, 2015.
	-5	Principal payments based on a 30-year amortization schedule.
	Certain loans require us to comply with various financial covenants. As of March 31, 2015, the Operating Partnership was in compliance with these financial covenants.
	Unsecured notes payable
	The following is a summary of the Operating Partnership's total unsecured notes payable outstanding as of March 31, 2015 and December 31, 2014 (in thousands):
	Description of Debt	Principal Balance as of						Stated Interest Rate		Stated Maturity Date
		31-Mar-15			31-Dec-14			as of March 31, 2015
	Term Loan	$	100,000		$	100,000		Variable (1)		January 9, 2019 (2)
	Senior Guaranteed Notes, Series A	150,000			150,000			4.04% (3)		October 31, 2021
	Senior Guaranteed Notes, Series B	100,000			—			4.45	%	February 2, 2025
	Total Unsecured Notes Payable	$	350,000		$	250,000
	-1	The Operating Partnership has entered into an interest rate swap agreement that is intended to fix the interest rate associated with the loan term at approximately 3.08% through its maturity date and extension options, subject to adjustments based on our consolidated leverage ratio.
	-2	The Operating Partnership has an option to extend the term loan up to three times, with each such extension for a 12-month period. The foregoing extension options are exercisable by us subject to the satisfaction of certain conditions.
	-3	The Operating Partnership entered into a one-month forward-starting seven-year swap contract on August 19, 2014, which was settled on September 19, 2014 at a gain of approximately $1.6 million. The forward-starting seven-year swap contract was deemed to be a highly effective cash flow hedge, accordingly, the effective interest rate is approximately 3.88% per annum.
	On October 31, 2014, the Operating Partnership entered into a Note Purchase Agreement with a group of institutional purchasers that provided for the private placement of an aggregate of $350 million of senior guaranteed notes, of which (i) $150 million are designated as 4.04% Senior Guaranteed Notes, Series A, due October 31, 2021 (the “Series A Notes”), (ii) $100 million are designated as 4.45% Senior Guaranteed Notes, Series B, due February 2, 2025 (the “Series B Notes”) and (iii) $100 million are designated as 4.50% Senior Guaranteed Notes, Series C, due April 1, 2025 (the “Series C Notes”, and collectively with the Series A Notes and Series B Notes, are referred to herein as, the “Notes”). The Series A Notes were issued on October 31, 2014, the Series B Notes were issued on February 2, 2015 and the Series C Notes were issued on April 2, 2015. The Notes pay interest quarterly on the last day of January, April, July and October until their respective maturities.
	The Operating Partnership may prepay at any time all, or from time to time any part of, the Notes, in an amount not less than 5% of the aggregate principal amount of any series of the Notes then outstanding in the case of a partial prepayment, at 100% of the principal amount so prepaid plus a Make-Whole Amount (as defined in the Note Purchase Agreement).
	The Note Purchase Agreement contains a number of customary financial covenants, including, without limitation, tangible net worth thresholds, secured and unsecured leverage ratios and fixed charge coverage ratios. Subject to the terms of the Note Purchase Agreement and the Notes, upon certain events of default, including, but not limited to, (i) a default in the payment of any principal, Make-Whole Amount or interest under the Notes, and (ii) a default in the payment of certain other indebtedness by us or our subsidiaries, the principal, accrued and unpaid interest, and the Make-Whole Amount on the outstanding Notes will become due and payable at the option of the purchasers.
	The Operating Partnership's obligations under the Notes are fully and unconditionally guaranteed by the Operating Partnership and certain of the Operating Partnership's subsidiaries.
	Credit Facility
	On January 9, 2014, Operating Partnership entered into an amended and restated credit agreement (the "Amended and Restated Credit Facility") which amended and restated the then in-place credit facility. The Amended and Restated Credit Facility provides for aggregate, unsecured borrowing of $350 million, consisting of a revolving line of credit of $250 million (the "Revolver Loan") and a term loan of $100 million (the "Term Loan"). The Amended and Restated Credit Facility has an accordion feature that may allow the Operating Partnership to increase the availability thereunder up to an additional $250 million, subject to meeting specified requirements and obtaining additional commitments from lenders. At March 31, 2015, $20 million was outstanding under the Revolver Loan.
	Borrowings under the Amended and Restated Credit Facility initially bear interest at floating rates equal to, at our option, either (1) LIBOR, plus a spread which ranges from (a) 1.35%-1.95% (with respect to the Revolver Loan) and (b) 1.30% to 1.90% (with respect to the Term Loan), in each case based on our consolidated leverage ratio, or (2) a base rate equal to the highest of (a) the prime rate, (b) the federal funds rate plus 50 bps or (c) the Eurodollar rate plus 100 bps, plus a spread which ranges from (i) 0.35%-0.95% (with respect to the Revolver Loan) and (ii) 0.30% to 0.90% (with respect to the Term Loan), in each case based on our consolidated leverage ratio. If American Assets Trust, Inc. obtains an investment-grade debt rating, under the terms set forth in the Amended and Restated Credit Facility, the spreads will further improve.
	The Revolver Loan initially matures on January 9, 2018, subject to the Operating Partnership's option to extend the Revolver Loan up to two times, with each such extension for a six-month period. The Term Loan initially matures on January 9, 2016, subject to the Operating Partnership's option to extend the Term Loan up to three times, with each such extension for a 12-month period. The foregoing extension options are exercisable by the Operating Partnership's subject to the satisfaction of certain conditions.
	Concurrent with the closing of the Amended and Restated Credit Facility, the Operating Partnership's drew down on the entirety of the $100 million Term Loan and entered into an interest rate swap agreement that is intended to fix the interest rate associated with the Term Loan at approximately 3.08% through its maturity date and extension options, subject to adjustments based on our consolidated leverage ratio.
	Additionally, the Amended and Restated Credit Facility includes a number of customary financial covenants, including:
	•	A maximum leverage ratio (defined as total indebtedness net of certain cash and cash equivalents to total asset value) of 60%,
	•	A maximum secured leverage ratio (defined as total secured debt to secured total asset value) of 45% at any time prior to December 31, 2015, and 40% thereafter,
	•	A minimum fixed charge coverage ratio (defined as consolidated earnings before interest, taxes, depreciation and amortization to consolidated fixed charges) of 1.50x,
	•	A minimum unsecured interest coverage ratio of 1.75x,
	•	A maximum unsecured leverage ratio of 60%,
	•	A minimum tangible net worth of $721.16 million, and 75% of the net proceeds of any additional equity issuances (other than additional equity issuances in connection with any dividend reinvestment program), and
	•	Recourse indebtedness at any time cannot exceed 15% of total asset value.
	The Amended and Restated Credit Facility provides that American Assets Trust, Inc.'s annual distributions may not exceed the greater of (1) 95% of our funds from operations or (2) the amount required for us to (a) qualify and maintain our REIT status and (b) avoid the payment of federal or state income or excise tax. If certain events of default exist or would result from a distribution, we may be precluded from making distributions other than those necessary to qualify and maintain our status as a REIT.
	As of March 31, 2015, the Operating Partnership was in compliance with the Amended and Restated Credit Facility financial covenants.

PARTNERS_CAPITAL_OF_AMERICAN_A

PARTNERS CAPITAL OF AMERICAN ASSETS TRUST, L.P. (Notes)	3 Months Ended
	Mar. 31, 2015
Equity [Abstract]
PARTNERS' CAPITAL OF AMERICAN ASSETS TRUST, L.P.	PARTNERS' CAPITAL OF AMERICAN ASSETS TRUST, L.P.
	Noncontrolling interests in our Operating Partnership are interests in the Operating Partnership that are not owned by us. Noncontrolling interests consisted of 17,899,516 common units (the “noncontrolling common units”), and represented approximately 29.1% of the ownership interests in our Operating Partnership at March 31, 2015. Common units and shares of our common stock have essentially the same economic characteristics in that common units and shares of our common stock share equally in the total net income or loss distributions of our Operating Partnership. Investors who own common units have the right to cause our Operating Partnership to redeem any or all of their common units for cash equal to the then-current market value of one share of our common stock, or, at our election, shares of our common stock on a one-for-one basis.
	During the three months ended March 31, 2015, approximately 5,741 common units were converted into shares of our common stock.

EQUITY_OF_AMERICAN_ASSETS_TRUS

EQUITY OF AMERICAN ASSETS TRUST, INC.	3 Months Ended
	Mar. 31, 2015
Equity [Abstract]
EQUITY OF AMERICAN ASSETS TRUST, INC.	EQUITY OF AMERICAN ASSETS TRUST, INC.
	Stockholders' Equity
	On May 6, 2013, we entered into an at-the-market (“ATM”) equity program with four sales agents in which we may, from time to time, offer and sell shares of our common stock having an aggregate offering price of up to $150.0 million. The sales of shares of our common stock made through the ATM equity program are made in "at-the-market" offerings as defined in Rule 415 of the Securities Act of 1933, as amended. During the three months ended March 31, 2015, the following shares of common stock and related proceeds were sold through the ATM equity program (in thousands, except per share data):
		Three Months Ended March 31, 2015
	Number of shares of common stock issued through ATM program	53,800
	Weighted average price per share	$42.54
	Proceeds, gross	$	2,288
	Sales agent compensation	(23		)
	Offering costs	(101		)
	Proceeds, net	$	2,164
	We intend to use the net proceeds from the ATM equity program to fund our development or redevelopment activities, repay amounts outstanding from time to time under our revolving line of credit or other debt financing obligations, fund potential acquisition opportunities and/or for general corporate purposes. As of March 31, 2015, we had the capacity to issue up to an additional $30.1 million in shares of our common stock under our ATM equity program. Actual future sales will depend on a variety of factors including, but not limited to, market conditions, the trading price of our common stock and our capital needs. We have no obligation to sell the remaining shares available for sale under the ATM equity program.
	On March 9, 2015, we entered into a common stock purchase agreement (the “Purchase Agreement”) with Explorer Insurance Company, a California corporation ("EIC"), an entity owned and controlled by Ernest Rady, the Executive Chairman of our board of directors. The Purchase Agreement provided for the sale by us to EIC, in a private placement, of 200,000 shares of our common stock at a purchase price of $40.54 per share, resulting in gross proceeds to us of approximately $8.1 million. The price per share paid by EIC was equal to the closing price of a share of our common stock on the New York Stock Exchange on the date of the Purchase Agreement. These shares were registered on March 27, 2015 by virtue of our filing of a prospectus supplement to our universal shelf registration statement on Form S-3 filed on February 6, 2015.
	Dividends
	The following table lists the dividends declared and paid on our shares of common stock and noncontrolling common units during the three months ended March 31, 2015:
	Period		Amount  per				Period Covered		Dividend Paid Date
			Share/Unit
	First Quarter 2015		$	0.2325			January 1, 2015 to March 31, 2015		March 27, 2015
	Taxability of Dividends
	Earnings and profits, which determine the taxability of distributions to stockholders and holders of common units, may differ from income reported for financial reporting purposes due to the differences for federal income tax purposes in the treatment of revenue recognition and compensation expense and in the basis of depreciable assets and estimated useful lives used to compute depreciation.
	Stock-Based Compensation
	We follow the FASB guidance related to stock compensation which establishes financial accounting and reporting standards for stock-based employee compensation plans, including all arrangements by which employees receive shares of stock or other equity instruments of the employer, or the employer incurs liabilities to employees in amounts based on the price of the employer's stock.  The guidance also defines a fair value-based method of accounting for an employee stock option or similar equity instrument.
	For the performance-based stock awards, the fair value of the awards were estimated using a Monte Carlo Simulation model. Our stock price, along with the stock prices of a group of peer REITs, is assumed to follow the Multivariate Geometric Brownian Motion Process. Multivariate Geometric Brownian Motion is a common assumption when modeling in financial markets, as it allows the modeled quantity (in this case, the stock price) to vary randomly from its current value and take any value greater than zero. The volatilities of the returns on the stock price of the Company and the group of REITs were estimated based on a three year look-back period. The expected growth rate of the stock prices over the “derived service period” of the employee is determined with consideration of the risk free rate as of the grant date.
	The following table summarizes the activity of restricted stock awards during the three months ended March 31, 2015:
		Units			Weighted Average Grant Date Fair Value
	Nonvested at January 1, 2015	493,539			$	22.01
	Granted	—			—
	Vested	(308,587	)		15.36
	Forfeited	—			—
	Nonvested at March 31, 2015	184,952			$	33.1
	We recognize noncash compensation expense ratably over the vesting period, and accordingly, we recognized $0.9 million and $0.5 million, respectively, in noncash compensation expense for the three months ended March 31, 2015 and 2014, which is included in general and administrative expense on the consolidated statements of comprehensive income. Unrecognized compensation expense was $3.9 million at March 31, 2015.
	Earnings Per Share
	We have calculated earnings per share (“EPS”) under the two-class method. The two-class method is an earnings allocation methodology whereby EPS for each class of common stock and participating security is calculated according to dividends declared and participation rights in undistributed earnings. The weighted average unvested shares outstanding, which are considered participating securities, were 246,672 and 406,856 for the three months ended March 31, 2015 and 2014. Therefore, we have allocated our earnings for basic and diluted EPS between common shares and unvested shares as these unvested shares have nonforfeitable dividend equivalent rights.
	Diluted EPS is calculated by dividing the net income applicable to common stockholders for the period by the weighted average number of common and dilutive instruments outstanding during the period using the treasury stock method. For the three months ended March 31, 2015 and 2014, diluted shares exclude incentive restricted stock as these awards are considered contingently issuable. Additionally, the unvested restricted stock awards subject to time vesting are anti-dilutive for all periods presented, and accordingly, have been excluded from the weighted average common shares used to compute diluted EPS.
	Earnings Per Unit of the Operating Partnership
	Basic earnings (loss) per unit (“EPU”) of the Operating Partnership is computed by dividing income (loss) applicable to unitholders by the weighted average Operating Partnership units outstanding, as adjusted for the effect of participating securities. Operating Partnership units granted in equity-based payment transactions are considered participating securities prior to vesting. The impact of unvested Operating Partnership unit awards on EPU has been calculated using the two-class method whereby earnings are allocated to the unvested Operating Partnership unit awards based on distributions and the unvested Operating Partnership units’ participation rights in undistributed earnings (losses).
	The calculation of diluted earnings per unit for the year ended March 31, 2015 and 2014 does not include the weighted average of 246,672, and 406,856 unvested Operating Partnership units, respectively, as these equity securities are either considered contingently issuable or the effect of including these equity securities was anti-dilutive to income from continuing operations and net income attributable to the unitholders.
	The computation of basic and diluted EPS is presented below (dollars in thousands, except share and per share amounts):
		Three Months Ended March 31,
		2015				2014
	NUMERATOR
	Net income from operations	$	11,379			$	6,658
	Less: Net income attributable to restricted shares	(43		)		(70		)
	Less: Income from operations attributable to unitholders in the Operating Partnership	(3,309		)		(1,986		)
	Net income attributable to common stockholders—basic	$	8,027			$	4,602
	Income from operations attributable to American Assets Trust, Inc. common stockholders—basic	$	8,027			$	4,602
	Plus: Income from operations attributable to unitholders in the Operating Partnership	3,309				1,986
	Net income attributable to common stockholders—diluted	$	11,336			$	6,588
	DENOMINATOR
	Weighted average common shares outstanding—basic	43,419,762				40,582,792
	Effect of dilutive securities—conversion of Operating Partnership units	17,901,685				17,909,681
	Weighted average common shares outstanding—diluted	61,321,447				58,492,473
	Earnings per common share, basic	$	0.18			$	0.11
	Earnings per common share, diluted	$	0.18			$	0.11

INCOME_TAXES

INCOME TAXES	3 Months Ended
	Mar. 31, 2015
Income Tax Disclosure [Abstract]
INCOME TAXES	INCOME TAXES
	We elected to be taxed as a REIT and operate in a manner that allows us to qualify as a REIT for federal income tax purposes commencing with our initial taxable year. As a REIT, we are generally not subject to corporate level income tax on the earnings distributed currently to our stockholders that we derive from our REIT qualifying activities. Taxable income from non-REIT activities managed through our TRS is subject to federal and state income taxes.
	We lease our hotel property to a wholly owned TRS that is subject to federal and state income taxes. We account for income taxes using the asset and liability method, under which deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between GAAP carrying amounts and their respective tax bases. Additionally, we classify certain state taxes as income taxes for financial reporting purposes in accordance with ASC Topic 740, Income Taxes.
	A deferred tax liability of $0.2 million as of March 31, 2015 and December 31, 2014 is included in our consolidated balance sheets in relation to real estate asset basis differences of property subject to the Texas margin tax and certain prepaid expenses of our TRS.
	Income tax expense is recorded in other income (expense), net in our consolidated statements of comprehensive income. For each of the three months ended March 31, 2015 and 2014 we recorded an income tax expense of $0.1 million.

COMMITMENTS_AND_CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	3 Months Ended
	Mar. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	COMMITMENTS AND CONTINGENCIES
	Legal
	We are sometimes involved in various disputes, lawsuits, warranty claims, environmental and other matters arising in the ordinary course of business. Management makes assumptions and estimates concerning the likelihood and amount of any potential loss relating to these matters.
	We are currently a party to various legal proceedings. We accrue a liability for litigation if an unfavorable outcome is probable and the amount of loss can be reasonably estimated. If an unfavorable outcome is probable and a reasonable estimate of the loss is a range, we accrue the best estimate within the range; however, if no amount within the range is a better estimate than any other amount, the minimum within the range is accrued. Legal fees related to litigation are expensed as incurred. We do not believe that the ultimate outcome of these matters, either individually or in the aggregate, could have a material adverse effect on our financial position or overall trends in results of operations; however, litigation is subject to inherent uncertainties. Also, under our leases, tenants are typically obligated to indemnify us from and against all liabilities, costs and expenses imposed upon or asserted against us as owner of the properties due to certain matters relating to the operation of the properties by the tenant.
	Commitments
	At The Landmark at One Market, we lease, as lessee, a building adjacent to The Landmark under an operating lease effective through June 30, 2016, which we have the option to extend until 2031 by way of three five-year extension options.
	At Waikiki Beach Walk, we sublease a portion of the building of which Quiksilver is currently in possession, under an operating lease effective through December 31, 2021, which we have the option to extend at fair rental value in the event the sublessor extends its lease for the space with the master landlord. The lease payments under the lease will increase by approximately 3.4% annually through 2017 and, thereafter, will be equal to fair rental value, as defined in the lease, through lease expiration.
	Current minimum annual payments under the leases are as follows, as of March 31, 2015 (in thousands):
	Year Ending December 31,
	2015 (nine months ending December 31, 2015)	$	1,986
	2016	2,682		(1)
	2017	2,686		(2)
	2018	2,686
	2019	2,686
	Thereafter	23,856
	Total	$	36,582
	-1	Lease payments on The Landmark at One Market lease will be equal to fair rental value from July 2016 through the end of the options lease term. In the table, we have shown the option lease payments for this period based on the stated rate for the month of June 2016 of $162,140.
	-2	Lease payments on the Waikiki Beach Walk lease will be equal to fair rental value from March 2017 through the end of the lease term. In the table, we have shown the lease payments for this period based on the stated rate for the month of February 2017 of $61,690.
	We have management agreements with Outrigger Hotels & Resorts or an affiliate thereof (“Outrigger”) pursuant to which Outrigger manages each of the retail and hotel portions of the Waikiki Beach Walk property. Under the management agreement with Outrigger relating to the retail portion of Waikiki Beach Walk (the “retail management agreement”), we pay Outrigger a monthly management fee of 3.0% of net revenues from the retail portion of Waikiki Beach Walk. Pursuant to the terms of the retail management agreement, if the agreement is terminated in certain instances, including our election not to repair damage or destruction at the property, a condemnation or our failure to make required working capital infusions, we would be obligated to pay Outrigger a termination fee equal to the sum of the management fees paid for the two calendar months immediately preceding the termination date. The retail management agreement may not be terminated by us or by Outrigger without cause. Under our management agreement with Outrigger relating to the hotel portion of Waikiki Beach Walk (the “hotel management agreement”), we pay Outrigger a monthly management fee of 6.0% of the hotel's gross operating profit, as well as 3.0% of the hotel's gross revenues; provided that the aggregate management fee payable to Outrigger for any year shall not exceed 3.5% of the hotel's gross revenues for such fiscal year. Pursuant to the terms of the hotel management agreement, if the agreement is terminated in certain instances, including upon a transfer by us of the hotel or upon a default by us under the hotel management agreement, we would be required to pay a cancellation fee calculated by multiplying (1) the management fees for the previous 12 months by (2) (a) eight, if the agreement is terminated in the first 11 years of its term, or (b) four, three, two or one, if the agreement is terminated in the twelfth, thirteenth, fourteenth or fifteenth year, respectively, of its term. The hotel management agreement may not be terminated by us or by Outrigger without cause.
	A wholly owned subsidiary of our Operating Partnership, WBW Hotel Lessee LLC, entered into a franchise license agreement with Embassy Suites Franchise LLC, the franchisor of the brand “Embassy Suites™,” to obtain the non-exclusive right to operate the hotel under the Embassy SuitesTM brand for 20 years. The franchise license agreement provides that WBW Hotel Lessee LLC must comply with certain management, operational, record keeping, accounting, reporting and marketing standards and procedures. In connection with this agreement, we are also subject to the terms of a product improvement plan pursuant to which we expect to undertake certain actions to ensure that our hotel's infrastructure is maintained in compliance with the franchisor's brand standards. In addition, we must pay to Embassy Suites Franchise LLC a monthly franchise royalty fee equal to 4.0% of the hotel's gross room revenue through December 2021 and 5.0% of the hotel's gross room revenue thereafter, as well as a monthly program fee equal to 4.0% of the hotel's gross room revenue. If the franchise license is terminated due to our failure to make required improvements or to otherwise comply with its terms, we may be liable to the franchisor for a termination payment, which could be as high as $6.6 million based on operating performance through March 31, 2015.
	Our Del Monte Center property has ongoing environmental remediation related to ground water contamination. The environmental issue existed at purchase and remains in remediation. The final stages of the remediation will include routine, long term ground monitoring by the appropriate regulatory agency over the next two to nine years. The work performed is financed through an escrow account funded by the seller upon purchase of the Del Monte Center. We believe the funds in the escrow account are sufficient for the remaining work to be performed. However, if further work is required costing more than the remaining escrow funds, we could be required to pay such overage, although we may have a contractual claim for such costs against the prior owner or our environmental remediation consultant.
	In connection with our initial public offering, we entered into tax protection agreements with certain limited partners of our Operating Partnership. These agreements provide that if we dispose of any interest with respect to Carmel Country Plaza, Carmel Mountain Plaza, Del Monte Center, Loma Palisades, Lomas Santa Fe Plaza, Waikele Center or the ICW Plaza portion of Torrey Reserve Campus, in a taxable transaction during the period from the closing of our initial public offering through January 19, 2018, we will indemnify such limited partners for their tax liabilities attributable to their share of the built-in gain that existed with respect to such property interest as of the time of our initial public offering and tax liabilities incurred as a result of the reimbursement payment. Subject to certain exceptions and limitations, the indemnification rights will terminate for any such protected partner that sells, exchanges or otherwise disposes of more than 50% of his or her common units. We have no present intention to sell or otherwise dispose of the properties or interest therein in taxable transactions during the restriction period. If we were to trigger the tax protection provisions under these agreements, we would be required to pay damages in the amount of the taxes owed by these limited partners (plus additional damages in the amount of the taxes incurred as a result of such payment).
	Concentrations of Credit Risk
	Our properties are located in Southern California, Northern California, Hawaii, Oregon, Texas, and Washington. The ability of the tenants to honor the terms of their respective leases is dependent upon the economic, regulatory and social factors affecting the markets in which the tenants operate. Twelve of our consolidated properties are located in Southern California, which exposes us to greater economic risks than if we owned a more geographically diverse portfolio. Tenants in the retail industry accounted for 36.4% of total revenues for the three months ended March 31, 2015. This makes us susceptible to demand for retail rental space and subject to the risks associated with an investment in real estate with a concentration of tenants in the retail industry. Furthermore, tenants in the office industry accounted for 35.7% of total revenues for the three months ended March 31, 2015. This makes us susceptible to demand for office rental space and subject to the risks associated with an investment in real estate with a concentration of tenants in the office industry. For the three months ended March 31, 2015 and 2014, no tenant accounted for more than 10% of our total rental revenue.

OPERATING_LEASES

OPERATING LEASES	3 Months Ended
	Mar. 31, 2015
Leases [Abstract]
OPERATING LEASES	OPERATING LEASES
	Our leases with office, retail, mixed-use and residential tenants are classified as operating leases. Leases at our office and retail properties and the retail portion of our mixed-use property generally range from three to ten years (certain leases with anchor tenants may be longer), and in addition to minimum rents, usually provide for cost recoveries for the tenant’s share of certain operating costs and also may include percentage rents based on the tenant’s level of sales achieved. Leases on apartments generally range from 7 to 15 months, with a majority having 12-month lease terms. Rooms at the hotel portion of our mixed-use property are rented on a nightly basis.
	As of March 31, 2015, minimum future rentals from noncancelable operating leases, before any reserve for uncollectible amounts and assuming no early lease terminations, at our office and retail properties and the retail portion of our mixed-use property are as follows (in thousands):
	Year Ending December 31,
	2015 (nine months ending December 31, 2015)	$	121,921
	2016	149,336
	2017	133,727
	2018	101,180
	2019	72,885
	Thereafter	197,835
	Total	$	776,884
	The above future minimum rentals exclude residential leases, which typically have a term of 12 months or less, and exclude the hotel, as rooms are rented on a nightly basis.

COMPONENTS_OF_RENTAL_INCOME_AN

COMPONENTS OF RENTAL INCOME AND EXPENSE	3 Months Ended
	Mar. 31, 2015
Operating Leases, Income Statement, Lease Revenue [Abstract]
COMPONENTS OF RENTAL INCOME AND EXPENSE	COMPONENTS OF RENTAL INCOME AND EXPENSE
	The principal components of rental income are as follows (in thousands):
		Three Months Ended March 31,
		2015		2014
	Minimum rents
	Retail	$	18,211	$	17,292
	Office	21,187		20,236
	Multifamily	4,034		3,834
	Mixed-use	2,523		2,470
	Cost reimbursement	7,037		6,804
	Percentage rent	360		425
	Hotel revenue	9,008		9,002
	Other	393		419
	Total rental income	$	62,753	$	60,482
	Minimum rents include $0.7 million and $1.0 million for the three months ended March 31, 2015 and 2014, respectively, to recognize minimum rents on a straight-line basis. In addition, net amortization of above and below market leases included in minimum rents were $0.7 million and $0.6 million for the three months ended March 31, 2015 and 2014, respectively.
	The principal components of rental expenses are as follows (in thousands):
		Three Months Ended March 31,
		2015		2014
	Rental operating	$	6,281	$	6,526
	Hotel operating	5,645		5,553
	Repairs and maintenance	2,251		2,122
	Marketing	385		390
	Rent	614		611
	Hawaii excise tax	986		965
	Management fees	458		453
	Total rental expenses	$	16,620	$	16,620

OTHER_INCOME_EXPENSE_NET

OTHER INCOME (EXPENSE) , NET	3 Months Ended
	Mar. 31, 2015
Other Income and Expenses [Abstract]
OTHER INCOME (EXPENSE), NET	OTHER INCOME (EXPENSE), NET
	The principal components of other income (expense), net, are as follows (in thousands):
		Three Months Ended March 31,
		2015			2014
	Interest and investment income	$	14		$	21
	Income tax benefit (expense)	(84		)	(112		)
	Total other income (expense), net	$	(70	)	$	(91	)

RELATED_PARTY_TRANSACTIONS

RELATED PARTY TRANSACTIONS	3 Months Ended
	Mar. 31, 2015
Related Party Transactions [Abstract]
RELATED PARTY TRANSACTIONS	RELATED PARTY TRANSACTIONS
	At ICW Plaza, we lease space to Insurance Company of the West, a California corporation ("ICW") which is an insurance company majority owned and controlled by Ernest Rady, our Executive Chairman of the Board. Rental revenue recognized on the leases of $0.6 million and $0.5 million for the three months ended March 31, 2015 and 2014, respectively, is included in rental income. Additionally, on July 1, 2014, we entered into a workers' compensation insurance policy with ICW. The policy premium is approximately $0.4 million for the period July 1, 2014 through July 1, 2015.
	On September 12, 2014, we entered into a common stock Purchase Agreement with ICW. The Purchase Agreement provides for the sale by us to ICW, in a private placement, of 400,000 shares of common stock at a price of $33.76 per share, resulting in gross proceeds to us of approximately $13.5 million. The price per share paid by ICW was equal to the closing price of a share of our common stock on the New York Stock Exchange on the date of the Purchase Agreement.
	On March 9, 2015, we entered into a common stock Purchase Agreement with Explorer Insurance Company ("EIC"), an entity owned and controlled by Ernest Rady. The Purchase Agreement provides for the sale by us to EIC, in a private placement, of 200,000 shares of common stock at a price of $40.54 per share, resulting in gross proceeds to us of approximately $8.1 million. The price per share paid by EIC was equal to the closing price of a share of our common stock on the New York Stock Exchange on the date of the Purchase Agreement.
	As of March 31, 2015, Mr. Rady and his affiliates owned approximately 10.1% of our outstanding common stock and 24.1% of our outstanding common units, which together represent an approximate 34.1% beneficial interest in our company on a fully diluted basis.
	The Waikiki Beach Walk entities have a 47.7% investment in WBW CHP LLC, an entity that was formed to, among other things, construct a chilled water plant to provide air conditioning to the property and other adjacent facilities. The operating expenses of WBW CHP LLC are recovered through reimbursements from its members, and reimbursements to WBW CHP LLC of $0.2 million were made for both the three months ended March 31, 2015 and 2014 and are included in rental expenses on the statements of comprehensive income.

SEGMENT_REPORTING

SEGMENT REPORTING	3 Months Ended
	Mar. 31, 2015
Segment Reporting [Abstract]
SEGMENT REPORTING	SEGMENT REPORTING
	Segment information is prepared on the same basis that our management reviews information for operational decision-making purposes. We operate in four business segments: the acquisition, redevelopment, ownership and management of retail real estate, office real estate, multifamily real estate and mixed-use real estate. The products for our retail segment primarily include rental of retail space and other tenant services, including tenant reimbursements, parking and storage space rental. The products for our office segment primarily include rental of office space and other tenant services, including tenant reimbursements, parking and storage space rental. The products for our multifamily segment include rental of apartments and other tenant services. The products of our mixed-use segment include rental of retail space and other tenant services, including tenant reimbursements, parking and storage space rental and operation of a 369-room all-suite hotel.
	We evaluate the performance of our segments based on segment profit, which is defined as property revenue less property expenses. We do not use asset information as a measure to assess performance and make decisions to allocate resources. Therefore, depreciation and amortization expense is not allocated among segments. General and administrative expenses, interest expense, depreciation and amortization expense and other income and expense are not included in segment profit as our internal reporting addresses these items on a corporate level.
	Segment profit is not a measure of operating income or cash flows from operating activities as measured by GAAP, and it is not indicative of cash available to fund cash needs and should not be considered an alternative to cash flows as a measure of liquidity. Not all companies calculate segment profit in the same manner. We consider segment profit to be an appropriate supplemental measure to net income because it assists both investors and management in understanding the core operations of our properties.
	The following table represents operating activity within our reportable segments (in thousands):
		Three Months Ended March 31,
		2015			2014
	Total Retail
	Property revenue	$	24,038		$	22,999
	Property expense	(6,000		)	(6,058		)
	Segment profit	18,038			16,941
	Total Office
	Property revenue	23,577			22,858
	Property expense	(6,821		)	(6,893		)
	Segment profit	16,756			15,965
	Total Multifamily
	Property revenue	4,310			4,130
	Property expense	(1,484		)	(1,427		)
	Segment profit	2,826			2,703
	Total Mixed-Use
	Property revenue	14,110			13,993
	Property expense	(8,363		)	(8,268		)
	Segment profit	5,747			5,725
	Total segments’ profit	$	43,367		$	41,334
	The following table is a reconciliation of segment profit to net income attributable to stockholders (in thousands):
		Three Months Ended March 31,
		2015			2014
	Total segments’ profit	$	43,367		$	41,334
	General and administrative	(5,016		)	(4,612		)
	Depreciation and amortization	(15,107		)	(16,341		)
	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 unitholders in the Operating Partnership	(3,309		)	(1,986		)
	Net income attributable to American Assets Trust, Inc. stockholders	$	8,027		$	4,602
	The following table shows net real estate and secured note payable balances for each of the segments (in thousands):
		March 31, 2015			December 31, 2014
	Net Real Estate
	Retail	$	634,758		$	639,456
	Office	767,271			757,854
	Multifamily	210,569			182,468
	Mixed-Use	194,281			195,622
		$	1,806,879		$	1,775,400
	Secured Notes Payable (1)
	Retail	$	60,518		$	161,975
	Office	425,981			426,254
	Multifamily	101,444			101,444
	Mixed-Use	130,310			130,310
		$	718,253		$	819,983
	-1	Excludes unamortized fair market value adjustments of $6.4 million and $7.2 million as of March 31, 2015 and December 31, 2014, respectively.
	Capital expenditures for each segment for the three months ended March 31, 2015 and 2014 were as follows (in thousands):
		Three Months Ended March 31,
		2015			2014
	Capital Expenditures (1)
	Retail	$	935		$	1,506
	Office	14,714			7,091
	Multifamily	28,948			21,877
	Mixed-Use	371			822
		$	44,968		$	31,296
	-1	Capital expenditures represent cash paid for capital expenditures during the period and include leasing commissions paid.

SUBSEQUENT_EVENTS_Notes

SUBSEQUENT EVENTS (Notes)	3 Months Ended
	Mar. 31, 2015
Subsequent Events [Abstract]
SUBSEQUENT EVENTS	SUBSEQUENT EVENTS
	On April 2, 2015, we closed on and issued our Series C Notes. As of May 1, 2015, $100 million of the Series C Notes was outstanding.
	Additionally, on April 6, 2015, we prepaid in full, without premium or penalty, the secured mortgage encumbering The Landmark at One Market.

SUMMARY_OF_SIGNIFICANT_ACCOUNT1

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	3 Months Ended
	Mar. 31, 2015
Accounting Policies [Abstract]
Business and Organization	Business and Organization
	American Assets Trust, Inc. (which may be referred to in these financial statements as the “Company,” “we,” “us,” or “our”) is a Maryland corporation formed on July 16, 2010 that did not have any operating activity until the consummation of our initial public offering on January 19, 2011. The Company is the sole general partner of American Assets Trust, L.P., a Maryland limited partnership formed on July 16, 2010 (the “Operating Partnership”). The Company’s operations are carried on through our Operating Partnership and its subsidiaries, including our taxable real estate investment trust ("REIT") subsidiary ("TRS"). Since the formation of our Operating Partnership, the Company has controlled our Operating Partnership as its general partner and has consolidated its assets, liabilities and results of operations.
	We are a full service vertically integrated and self-administered REIT with approximately 127 employees providing substantial in-house expertise in asset management, property management, property development, leasing, tenant improvement construction, acquisitions, repositioning, redevelopment and financing.
	As of March 31, 2015, we owned or had a controlling interest in 23 office, retail, multifamily and mixed-use operating properties, the operations of which we consolidate. Additionally, as of March 31, 2015, we owned land at five of our properties that we classify as held for development and/or construction in progress. A summary of the properties owned by us is as follows:
	Retail
	Carmel Country Plaza	Del Monte Center
	Carmel Mountain Plaza	Geary Marketplace
	South Bay Marketplace	The Shops at Kalakaua
	Rancho Carmel Plaza	Waikele Center
	Lomas Santa Fe Plaza	Alamo Quarry Market
	Solana Beach Towne Centre
	Office
	Torrey Reserve Campus	Lloyd District Portfolio
	Solana Beach Corporate Centre	City Center Bellevue
	The Landmark at One Market
	One Beach Street
	First & Main
	Multifamily
	Loma Palisades
	Imperial Beach Gardens
	Mariner's Point
	Santa Fe Park RV Resort
	Mixed-Use
	Waikiki Beach Walk Retail and Embassy Suites™ Hotel
	Held for Development and/or Construction in Progress
	Solana Beach Corporate Centre – Land
	Solana Beach – Highway 101 – Land
	Torrey Point (formerly Sorrento Pointe) – Land
	Torrey Reserve – Land
	Lloyd District Portfolio – Land
Basis of Presentation	Basis of Presentation
	Our consolidated financial statements include the accounts of the Company, our Operating Partnership and our subsidiaries. The equity interests of other investors in our Operating Partnership are reflected as noncontrolling interests.
	All significant intercompany transactions and balances are eliminated in consolidation.
	The accompanying consolidated financial statements of the Company and the Operating Partnership have been prepared in accordance with the rules applicable to Form 10-Q and include all information and footnotes required for interim financial statement presentation, but do not include all disclosures required under accounting principles generally accepted in the United States (“GAAP”) for annual financial statements. In the opinion of management, all adjustments (consisting of normal recurring adjustments, except as otherwise noted) considered necessary for a fair presentation have been included. These financial statements should be read in conjunction with the audited consolidated financial statements and notes therein included in the Company's and Operating Partnership's annual report on Form 10-K for the year ended December 31, 2014.
	The preparation of financial statements in conformity with GAAP requires us to make estimates and assumptions that in certain circumstances affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities, and revenues and expenses. These estimates are prepared using our best judgment, after considering past, current and expected events and economic conditions. Actual results could differ from these estimates.
	Any reference to the number of properties and square footage are unaudited and outside the scope of our independent registered public accounting firm’s review of our financial statements in accordance with the standards of the United States Public Company Accounting Oversight Board.
Significant Accounting Policies	Significant Accounting Policies
	We describe our significant accounting policies in Note 1 to the consolidated financial statements in Item 8 of our Annual Report on Form 10-K for the year ended December 31, 2014. There have been no changes to our significant accounting policies during the three months ended March 31, 2015.
Segment Information	Segment Information
	Segment information is prepared on the same basis that our management reviews information for operational decision-making purposes. We operate in four business segments: the acquisition, redevelopment, ownership and management of retail real estate, office real estate, multifamily real estate and mixed-use real estate. The products for our retail segment primarily include rental of retail space and other tenant services, including tenant reimbursements, parking and storage space rental. The products for our office segment primarily include rental of office space and other tenant services, including tenant reimbursements, parking and storage space rental. The products for our multifamily segment include rental of apartments and other tenant services. The products of our mixed-use segment include rental of retail space and other tenant services, including tenant reimbursements, parking and storage space rental and operation of a 369-room all-suite hotel.
Recent Accounting Pronouncements	Recent Accounting Pronouncements
	In April 2014, the FASB issued Accounting Standards Update (ASU) 2014-08, Presentation of Financial Statements (Topic 205) and Property, Plant, and Equipment (Topic 360): Reporting Discontinued Operations and Disclosures of Disposals of Components of an Entity. ASU 2014-08 revises the definition of a discontinued operation to a disposal, sale or held-for-sale component or group of components that represents a strategic shift that will have a major effect on an entity's operations and financial results. This pronouncement is effective in 2015, however, calendar year-end companies may early adopt during the first quarter of 2014. We have chosen to early adopt this pronouncement and it became effective for us in the first quarter of 2014. This pronouncement did not have a significant impact on our consolidated financial statements.
	In May 2014, the FASB issued Update No. 2014-09, Revenue from Contracts with Customers. Update No. 2014-09 establishes that companies may recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. This pronouncement is effective for annual reporting periods beginning after December 15, 2016, including interim reporting periods within that reporting period; early adoption is not permitted. We are in the process of evaluating the impact this pronouncement will have on our consolidated financial statements.
	In February 2015, the FASB issued an ASU that requires reporting entities to evaluate whether they should consolidate certain legal entities. The ASU modifies the evaluation of whether limited partnerships and similar legal entities are VIEs or voting interest entities and eliminates the presumption that a general partner should consolidate a limited partnership. This affects the consolidation analysis of reporting entities that are involved with VIEs, particularly those that have fee arrangements and related party relationships. The ASU is effective for fiscal years, and for interim periods within those fiscal years, beginning after December 15, 2015, with early adoption permitted. A reporting entity may apply the amendments in the ASU using: (i) a modified retrospective approach by recording a cumulative-effect adjustment to equity as of the beginning of the fiscal year of adoption; or (ii) by applying the amendments retrospectively. We are in the process of evaluating the impact of adopting this ASU and currently do not expect that the adoption will have a material impact on our consolidated financial statements.
	In April 2015, the FASB issued an ASU that requires reporting entities to present debt issuance cost related to a note as a direct deduction from the face amount of that note presented in the balance sheet. The ASU requires the amortization of debt issuance costs presented as interest expense. The ASU is effective for fiscal years, and for interim periods within those fiscal years, beginning after December 15, 2015, with early adoption permitted. A reporting entity may apply the amendments in the ASU retrospectively to all prior periods. We do not expect that the adoption of this ASU will have a material impact on our consolidated financial statements.
Fair Value Measurements	A fair value measurement is based on the assumptions that market participants would use in pricing an asset or liability. The hierarchy for inputs used in measuring fair value is as follows:
	1	Level 1 Inputs—quoted prices in active markets for identical assets or liabilities
	2	Level 2 Inputs—observable inputs other than quoted prices in active markets for identical assets and liabilities
	3	Level 3 Inputs—unobservable inputs
	Except as disclosed below, the carrying amounts of our financial instruments approximate their fair value. In certain cases, the inputs used to measure fair value may fall into different levels of the fair value hierarchy. In such cases, for disclosure purposes, the level within which the fair value measurement is categorized is based on the lowest level input that is significant to the fair value measurement.

SUMMARY_OF_SIGNIFICANT_ACCOUNT2

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)	3 Months Ended
	Mar. 31, 2015
Accounting Policies [Abstract]
Consolidated Statements of Cash Flows-Supplemental Disclosures	The following table provides supplemental disclosures related to the Consolidated Statements of Cash Flows (in thousands):
		Three Months Ended March 31,
		2015			2014
	Supplemental cash flow information
	Total interest costs incurred	$	14,128		$	14,467
	Interest capitalized	$	2,333		$	835
	Interest expense	$	11,795		$	13,632
	Cash paid for interest, net of amounts capitalized	$	10,459		$	12,724
	Cash paid for income taxes	$	50		$	—
	Supplemental schedule of noncash investing and financing activities
	Accounts payable and accrued liabilities for construction in progress	$	205		$	(890	)
	Accrued leasing commissions	$	(166	)	$	(630	)

ACQUIRED_INPLACE_LEASES_AND_AB1

ACQUIRED IN-PLACE LEASES AND ABOVE/BELOW MARKET LEASES (Tables)	3 Months Ended
	Mar. 31, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of acquired lease intangibles included in other assets and other liabilities	The following summarizes our acquired lease intangibles and leasing costs, which are included in other assets and other liabilities and deferred credits, as of March 31, 2015 and December 31, 2014 (in thousands):
		March 31, 2015			December 31, 2014
	In-place leases	$	53,383		$	53,967
	Accumulated amortization	(36,001		)	(35,336		)
	Above market leases	22,291			22,500
	Accumulated amortization	(17,644		)	(17,397		)
	Acquired lease intangible assets, net	$	22,029		$	23,734
	Below market leases	$	70,013		$	70,013
	Accumulated accretion	(28,344		)	(27,161		)
	Acquired lease intangible liabilities, net	$	41,669		$	42,852

FAIR_VALUE_OF_FINANCIAL_INSTRU1

FAIR VALUE OF FINANCIAL INSTRUMENTS (Tables)	3 Months Ended
	Mar. 31, 2015
Fair Value Disclosures [Abstract]
Financial liabilities measured at fair value on recurring basis	A summary of our financial liabilities that are measured at fair value on a recurring basis, by level within the fair value hierarchy is as follows (in thousands):
		March 31, 2015											December 31, 2014
		Level 1		Level 2			Level 3			Total			Level 1		Level 2		Level 3		Total
	Deferred compensation liability	$	—	$	1,042		$	—		$	1,042		$	—	$	981	$	—	$	981
	Interest rate swap	$	—	$	2,391		$	—		$	2,391		$	—	$	1,448	$	—	$	1,448
Carrying amount and fair value of financial instruments	A summary of the carrying amount and fair value of our secured financial instruments, all of which are based on Level 2 inputs, is as follows (in thousands):
		March 31, 2015							December 31, 2014
		Carrying Value			Fair Value				Carrying Value			Fair Value
	Secured notes payable	$	711,809		$	750,138			$	812,811		$	850,475
	Unsecured term loan	$	100,000		$	100,000			$	100,000		$	100,000
	Unsecured senior guaranteed notes	$	250,000		$	260,019			$	150,000		$	154,560
	Unsecured line of credit	$	20,000		$	20,000			$	—		$	—

DERIVATIVE_AND_HEDGING_Tables

DERIVATIVE AND HEDGING (Tables)	3 Months Ended
	Mar. 31, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Interest Rate Derivatives [Table Text Block]	The following is a summary of the terms of the interest rate swap as of March 31, 2015 (dollars in thousands):
	Swap Counterparty	Notional Amount		Effective Date	Maturity Date	Fair Value
	Bank of America, N.A.	$	100,000	1/9/14	1/9/19	$	2,391

OTHER_ASSETS_Tables

OTHER ASSETS (Tables)	3 Months Ended
	Mar. 31, 2015
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Components of Other Assets	Other assets consist of the following (in thousands):
		March 31, 2015		December 31, 2014
	Leasing commissions, net of accumulated amortization of $21,392 and $20,659 respectively	$	19,197	$	19,484
	Acquired above market leases, net	4,647		5,103
	Acquired in-place leases, net	17,382		18,631
	Lease incentives, net of accumulated amortization of $3,053 and $2,960, respectively	647		740
	Other intangible assets, net of accumulated amortization of $1,612 and $1,590, respectively	411		453
	Debt issuance costs, net of accumulated amortization of $4,416 and $4,147, respectively	5,083		5,361
	Prepaid expenses and other	4,773		3,629
	Total other assets	$	52,140	$	53,401

OTHER_LIABILITIES_AND_DEFERRED1

OTHER LIABILITIES AND DEFERRED CREDITS (Tables)	3 Months Ended
	Mar. 31, 2015
Other Liabilities Disclosure [Abstract]
Other liabilities and deferred credits	Other liabilities and deferred credits consist of the following (in thousands):
		March 31, 2015		December 31, 2014
	Acquired below market leases, net	$	41,669	$	42,852
	Prepaid rent and deferred revenue	7,538		7,288
	Interest rate swap liability	2,391		1,448
	Deferred rent expense and lease intangible	511		584
	Deferred compensation	1,042		981
	Deferred tax liability	219		219
	Straight-line rent liability	2,410		2,533
	Other liabilities	87		88
	Total other liabilities and deferred credits, net	$	55,867	$	55,993

DEBT_Tables

DEBT (Tables)	3 Months Ended
	Mar. 31, 2015
Debt Disclosure [Abstract]
Summary of total secured notes payable outstanding	The following is a summary of our total secured notes payable outstanding as of March 31, 2015 and December 31, 2014 (in thousands):
		Principal Balance as of						Stated Interest Rate		Stated Maturity Date
	Description of Debt	March 31, 2015			December 31, 2014			as of March 31, 2015
	The Shops at Kalakaua (1)(2)	$	—		$	19,000		—		May 1, 2015
	The Landmark at One Market (1)(3)	133,000			133,000			5.61	%	July 5, 2015
	Del Monte Center (1)(4)	—			82,300			—		July 8, 2015
	First & Main (1)	84,500			84,500			3.97	%	July 1, 2016
	Imperial Beach Gardens (1)	20,000			20,000			6.16	%	September 1, 2016
	Mariner’s Point (1)	7,700			7,700			6.09	%	September 1, 2016
	South Bay Marketplace (1)	23,000			23,000			5.48	%	February 10, 2017
	Waikiki Beach Walk—Retail (1)	130,310			130,310			5.39	%	July 1, 2017
	Solana Beach Corporate Centre III-IV (5)	36,257			36,376			6.39	%	August 1, 2017
	Loma Palisades (1)	73,744			73,744			6.09	%	July 1, 2018
	One Beach Street (1)	21,900			21,900			3.94	%	April 1, 2019
	Torrey Reserve—North Court (5)	20,995			21,075			7.22	%	June 1, 2019
	Torrey Reserve—VCI, VCII, VCIII (5)	7,074			7,101			6.36	%	June 1, 2020
	Solana Beach Corporate Centre I-II (5)	11,255			11,302			5.91	%	June 1, 2020
	Solana Beach Towne Centre (5)	37,518			37,675			5.91	%	June 1, 2020
	City Center Bellevue (1)	111,000			111,000			3.98	%	November 1, 2022
		718,253			819,983
	Unamortized fair value adjustment	(6,444		)	(7,172		)
	Total Secured Notes Payable Outstanding	$	711,809		$	812,811
	-1	Interest only.
	-2	Loan repaid in full, without premium or penalty, on February 2, 2015.
	-3	Loan repaid in full, without premium or penalty, on April 6, 2015.
	-4	Loan repaid in full, without premium or penalty, on February 6, 2015.
	-5	Principal payments based on a 30-year amortization schedule.

EQUITY_OF_AMERICAN_ASSETS_TRUS1

EQUITY OF AMERICAN ASSETS TRUST, INC. (Tables)	3 Months Ended
	Mar. 31, 2015
Equity [Abstract]
Schedule of At-the-Market Program	During the three months ended March 31, 2015, the following shares of common stock and related proceeds were sold through the ATM equity program (in thousands, except per share data):
		Three Months Ended March 31, 2015
	Number of shares of common stock issued through ATM program	53,800
	Weighted average price per share	$42.54
	Proceeds, gross	$	2,288
	Sales agent compensation	(23		)
	Offering costs	(101		)
	Proceeds, net	$	2,164
Dividends declared and paid on shares of common stock and noncontrolling common units	The following table lists the dividends declared and paid on our shares of common stock and noncontrolling common units during the three months ended March 31, 2015:
	Period		Amount  per				Period Covered		Dividend Paid Date
			Share/Unit
	First Quarter 2015		$	0.2325			January 1, 2015 to March 31, 2015		March 27, 2015
Activity of restricted stock awards	The following table summarizes the activity of restricted stock awards during the three months ended March 31, 2015:
		Units			Weighted Average Grant Date Fair Value
	Nonvested at January 1, 2015	493,539			$	22.01
	Granted	—			—
	Vested	(308,587	)		15.36
	Forfeited	—			—
	Nonvested at March 31, 2015	184,952			$	33.1
Computation of basic and diluted EPS	The computation of basic and diluted EPS is presented below (dollars in thousands, except share and per share amounts):
		Three Months Ended March 31,
		2015				2014
	NUMERATOR
	Net income from operations	$	11,379			$	6,658
	Less: Net income attributable to restricted shares	(43		)		(70		)
	Less: Income from operations attributable to unitholders in the Operating Partnership	(3,309		)		(1,986		)
	Net income attributable to common stockholders—basic	$	8,027			$	4,602
	Income from operations attributable to American Assets Trust, Inc. common stockholders—basic	$	8,027			$	4,602
	Plus: Income from operations attributable to unitholders in the Operating Partnership	3,309				1,986
	Net income attributable to common stockholders—diluted	$	11,336			$	6,588
	DENOMINATOR
	Weighted average common shares outstanding—basic	43,419,762				40,582,792
	Effect of dilutive securities—conversion of Operating Partnership units	17,901,685				17,909,681
	Weighted average common shares outstanding—diluted	61,321,447				58,492,473
	Earnings per common share, basic	$	0.18			$	0.11
	Earnings per common share, diluted	$	0.18			$	0.11

COMMITMENTS_AND_CONTINGENCIES_

COMMITMENTS AND CONTINGENCIES (Tables)	3 Months Ended
	Mar. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Current minimum annual payments under the leases	Current minimum annual payments under the leases are as follows, as of March 31, 2015 (in thousands):
	Year Ending December 31,
	2015 (nine months ending December 31, 2015)	$	1,986
	2016	2,682		(1)
	2017	2,686		(2)
	2018	2,686
	2019	2,686
	Thereafter	23,856
	Total	$	36,582
	-1	Lease payments on The Landmark at One Market lease will be equal to fair rental value from July 2016 through the end of the options lease term. In the table, we have shown the option lease payments for this period based on the stated rate for the month of June 2016 of $162,140.
	-2	Lease payments on the Waikiki Beach Walk lease will be equal to fair rental value from March 2017 through the end of the lease term. In the table, we have shown the lease payments for this period based on the stated rate for the month of February 2017 of $61,690.

OPERATING_LEASES_Tables

OPERATING LEASES (Tables)	3 Months Ended
	Mar. 31, 2015
Leases [Abstract]
Current minimum future rentals under the leases	As of March 31, 2015, minimum future rentals from noncancelable operating leases, before any reserve for uncollectible amounts and assuming no early lease terminations, at our office and retail properties and the retail portion of our mixed-use property are as follows (in thousands):
	Year Ending December 31,
	2015 (nine months ending December 31, 2015)	$	121,921
	2016	149,336
	2017	133,727
	2018	101,180
	2019	72,885
	Thereafter	197,835
	Total	$	776,884

COMPONENTS_OF_RENTAL_INCOME_AN1

COMPONENTS OF RENTAL INCOME AND EXPENSE (Tables)	3 Months Ended
	Mar. 31, 2015
Operating Leases, Income Statement, Lease Revenue [Abstract]
Principal components of rental income	The principal components of rental income are as follows (in thousands):
		Three Months Ended March 31,
		2015		2014
	Minimum rents
	Retail	$	18,211	$	17,292
	Office	21,187		20,236
	Multifamily	4,034		3,834
	Mixed-use	2,523		2,470
	Cost reimbursement	7,037		6,804
	Percentage rent	360		425
	Hotel revenue	9,008		9,002
	Other	393		419
	Total rental income	$	62,753	$	60,482
Principal components of rental expenses	The principal components of rental expenses are as follows (in thousands):
		Three Months Ended March 31,
		2015		2014
	Rental operating	$	6,281	$	6,526
	Hotel operating	5,645		5,553
	Repairs and maintenance	2,251		2,122
	Marketing	385		390
	Rent	614		611
	Hawaii excise tax	986		965
	Management fees	458		453
	Total rental expenses	$	16,620	$	16,620

OTHER_INCOME_EXPENSE_NET_Table

OTHER INCOME (EXPENSE) , NET (Tables)	3 Months Ended
	Mar. 31, 2015
Other Income and Expenses [Abstract]
Principal components of other income (expense), net	The principal components of other income (expense), net, are as follows (in thousands):
		Three Months Ended March 31,
		2015			2014
	Interest and investment income	$	14		$	21
	Income tax benefit (expense)	(84		)	(112		)
	Total other income (expense), net	$	(70	)	$	(91	)

SEGMENT_REPORTING_Tables

SEGMENT REPORTING (Tables)	3 Months Ended
	Mar. 31, 2015
Segment Reporting [Abstract]
Schedule of segments operating activity	The following table represents operating activity within our reportable segments (in thousands):
		Three Months Ended March 31,
		2015			2014
	Total Retail
	Property revenue	$	24,038		$	22,999
	Property expense	(6,000		)	(6,058		)
	Segment profit	18,038			16,941
	Total Office
	Property revenue	23,577			22,858
	Property expense	(6,821		)	(6,893		)
	Segment profit	16,756			15,965
	Total Multifamily
	Property revenue	4,310			4,130
	Property expense	(1,484		)	(1,427		)
	Segment profit	2,826			2,703
	Total Mixed-Use
	Property revenue	14,110			13,993
	Property expense	(8,363		)	(8,268		)
	Segment profit	5,747			5,725
	Total segments’ profit	$	43,367		$	41,334
Reconciliation of segment profit to net income attributable to stockholders	The following table is a reconciliation of segment profit to net income attributable to stockholders (in thousands):
		Three Months Ended March 31,
		2015			2014
	Total segments’ profit	$	43,367		$	41,334
	General and administrative	(5,016		)	(4,612		)
	Depreciation and amortization	(15,107		)	(16,341		)
	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 unitholders in the Operating Partnership	(3,309		)	(1,986		)
	Net income attributable to American Assets Trust, Inc. stockholders	$	8,027		$	4,602
Net real estate and secured note payable balances by segments	The following table shows net real estate and secured note payable balances for each of the segments (in thousands):
		March 31, 2015			December 31, 2014
	Net Real Estate
	Retail	$	634,758		$	639,456
	Office	767,271			757,854
	Multifamily	210,569			182,468
	Mixed-Use	194,281			195,622
		$	1,806,879		$	1,775,400
	Secured Notes Payable (1)
	Retail	$	60,518		$	161,975
	Office	425,981			426,254
	Multifamily	101,444			101,444
	Mixed-Use	130,310			130,310
		$	718,253		$	819,983
	-1	Excludes unamortized fair market value adjustments of $6.4 million and $7.2 million as of March 31, 2015 and December 31, 2014, respectively.
Capital expenditures for each segment	Capital expenditures for each segment for the three months ended March 31, 2015 and 2014 were as follows (in thousands):
		Three Months Ended March 31,
		2015			2014
	Capital Expenditures (1)
	Retail	$	935		$	1,506
	Office	14,714			7,091
	Multifamily	28,948			21,877
	Mixed-Use	371			822
		$	44,968		$	31,296
	-1	Capital expenditures represent cash paid for capital expenditures during the period and include leasing commissions paid.

SUMMARY_OF_SIGNIFICANT_ACCOUNT3

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details)	3 Months Ended
	Mar. 31, 2015
	Segment
	Room
	Employee
	Property
Accounting Policies [Abstract]
Number of employees	127
Office, retail, multifamily, and mixed-use Operating properties	23
Properties held for development	5
Number of operating segments	4
Room in mixed-use segment all-suite hotel	369

SUMMARY_OF_SIGNIFICANT_ACCOUNT4

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Supplement Disclosures Related to Consolidated Statements of Cash Flows (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Accounting Policies [Abstract]
Total interest costs incurred	$14,128	$14,467
Interest capitalized	2,333	835
Interest expense	11,795	13,632
Cash paid for interest, net of amounts capitalized	10,459	12,724
Cash paid for income taxes	50	0
Accounts payable and accrued liabilities for construction in progress	205	-890
Accrued leasing commissions	($166)	($630)

ACQUIRED_INPLACE_LEASES_AND_AB2

ACQUIRED IN-PLACE LEASES AND ABOVE/BELOW MARKET LEASES Acquired Lease Intangibles and Leasing Costs Included in Other Assets and Other Liabilities and Deferred Credits (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Acquired Finite-Lived Intangible Assets [Line Items]
Acquired above market leases, net	$4,647	$5,103
Other intangible assets, accumulated amortization	-1,612	-1,590
Below market leases	70,013	70,013
Below market leases, accumulated amortization	-28,344	-27,161
Acquired lease intangible liabilities, net	41,669	42,852
Leases, Acquired-in-Place
Acquired Finite-Lived Intangible Assets [Line Items]
Acquired above market leases, net	53,383	53,967
Other intangible assets, accumulated amortization	-36,001	-35,336
Above Market Leases
Acquired Finite-Lived Intangible Assets [Line Items]
Acquired above market leases, net	22,291	22,500
Other intangible assets, accumulated amortization	-17,644	-17,397
Lease Agreements
Acquired Finite-Lived Intangible Assets [Line Items]
Acquired lease intangible assets, net	$22,029	$23,734

FAIR_VALUE_OF_FINANCIAL_INSTRU2

FAIR VALUE OF FINANCIAL INSTRUMENTS (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014	Jan. 09, 2014
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Unsecured notes payable	$350,000	$250,000
Fair value of interest rate swap	2,391	1,448
Interest Rate Swap
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Decrease in valuation of interest rate swaps	943
Interest Rate Swap | Deferred Credits and Other Liabilities
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value of interest rate swap	2,391
Amended and Restated Credit Facility
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Unsecured notes payable			100,000
Fair Value, Inputs, Level 2
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value of interest rate swap	$2,391	$1,448
Fair Value, Inputs, Level 2 | Minimum
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value assumptions, interest rate	3.37%
Fair Value, Inputs, Level 2 | Maximum
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value assumptions, interest rate	5.51%

FAIR_VALUE_OF_FINANCIAL_INSTRU3

FAIR VALUE OF FINANCIAL INSTRUMENTS - Financial Liabilities Fair Value Measurement on a Recurring Basis (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Deferred compensation liability	$1,042	$981
Fair value of interest rate swap	2,391	1,448
Fair Value, Inputs, Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Deferred compensation liability	0	0
Fair value of interest rate swap	0	0
Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Deferred compensation liability	1,042	981
Fair value of interest rate swap	2,391	1,448
Fair Value, Inputs, Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Deferred compensation liability	0	0
Fair value of interest rate swap	$0	$0

FAIR_VALUE_OF_FINANCIAL_INSTRU4

FAIR VALUE OF FINANCIAL INSTRUMENTS - Carrying Amount and Fair Value of Financial Instruments (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Secured notes payable | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Fair Value	$711,809	$812,811
Secured notes payable | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Fair Value	750,138	850,475
Unsecured term loan | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Fair Value	100,000	100,000
Unsecured term loan | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Fair Value	100,000	100,000
Unsecured senior guaranteed notes | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Fair Value	250,000	150,000
Unsecured senior guaranteed notes | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Fair Value	260,019	154,560
Unsecured line of credit | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Fair Value	20,000	0
Unsecured line of credit | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Fair Value	$20,000	$0

DERIVATIVE_AND_HEDGING_Details

DERIVATIVE AND HEDGING (Details) (USD $)	3 Months Ended
	Mar. 31, 2015	Dec. 31, 2014
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Fair Value	$2,391,000	$1,448,000
Interest Rate Swap | Designated as Hedging Instrument | Cash Flow Hedging
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative fixed interest rate (in percent)	3.08%
Notional Amount	100,000,000
Effective Date	9-Jan-14
Maturity Date	9-Jan-19
Fair Value	$2,391,000

OTHER_ASSETS_Details

OTHER ASSETS (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Leasing commissions, net of accumulated amortization of $21,392 and $20,659 respectively	$19,197	$19,484
Acquired above market leases, net	4,647	5,103
Acquired in-place leases, net	17,382	18,631
Lease incentives, net of accumulated amortization of $3,053 and $2,960, respectively	647	740
Other intangible assets, net of accumulated amortization of $1,612 and $1,590, respectively	411	453
Debt issuance costs, net of accumulated amortization of $4,416 and $4,147, respectively	5,083	5,361
Prepaid expenses and other	4,773	3,629
Total other assets	$52,140	$53,401

OTHER_ASSETS_Parenthetical_Det

OTHER ASSETS (Parenthetical) (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Leasing commissions, accumulative amortization	$21,392	$20,659
Lease incentives, accumulated amortization	3,053	2,960
Other intangible assets, accumulated amortization	1,612	1,590
Debt issuance costs, accumulated amortization	$4,416	$4,147

OTHER_LIABILITIES_AND_DEFERRED2

OTHER LIABILITIES AND DEFERRED CREDITS (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Other Liabilities Disclosure [Abstract]
Acquired below market leases, net	$41,669	$42,852
Prepaid rent and deferred revenue	7,538	7,288
Interest rate swap liability	2,391	1,448
Deferred rent expense and lease intangible	511	584
Deferred compensation	1,042	981
Deferred tax liability	219	219
Straight-line rent liability	2,410	2,533
Other liabilities	87	88
Total other liabilities and deferred credits, net	$55,867	$55,993

DEBT_Details

DEBT (Details) (USD $)	0 Months Ended
	Jan. 09, 2014	Oct. 31, 2014	Mar. 31, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Unsecured line of credit			$20,000,000	$0
Unsecured line of credit | Amended and Restated Credit Facility
Debt Instrument [Line Items]
Maximum leverage ratio of revolving credit facility (in percent)	60.00%
Maximum Unsecured Leverage Ratio	60.00%
Minimum Tangible Net Worth	721,160,000
Percent of net proceeds of any additional equity issuances in relation to net proceeds as of Offering	75.00%
Maximum Recourse Indebtedness of Total Asset Value	15.00%
Percentage limit on annual distributions in relation to funds from operations	95.00%
Unsecured line of credit | Amended and Restated Credit Facility | Base Rate
Debt Instrument [Line Items]
Debt Instrument, Spread on Variable Rate Basis, Two	0.50%
Debt Instrument, Spread on Variable Rate Basis, Three	1.00%
Unsecured term loan | Amended and Restated Credit Facility | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Debt Instrument, Description of Variable Rate Basis	LIBOR
Future Year Period Two | Unsecured line of credit
Debt Instrument [Line Items]
Minimum fixed charge coverage ratio on revolving credit facility (in percent)	1.5
Minimum Unsecured Interest Coverage Ratio	175.00%
Future Year Period Two | Unsecured line of credit | Amended and Restated Credit Facility
Debt Instrument [Line Items]
Maximum secured leverage ratio on revolving credit facility (in percent)	40.00%
Future Year Period One | Unsecured line of credit | Amended and Restated Credit Facility
Debt Instrument [Line Items]
Maximum secured leverage ratio on revolving credit facility (in percent)	45.00%
American Assets Trust, L.P.
Debt Instrument [Line Items]
Unsecured line of credit			20,000,000	0
American Assets Trust, L.P. | Amended and Restated Credit Facility
Debt Instrument [Line Items]
Revolving credit facility borrowing limit, maximum borrowing capacity	350,000,000
Line of Credit Facility, Allowable Additional Borrowing Capacity	250,000,000
Unsecured line of credit	100,000,000
American Assets Trust, L.P. | Unsecured senior guaranteed notes | Note Purchase Agreement
Debt Instrument [Line Items]
Face amount of debt		350,000,000
Partial debt repayment, minimum percentage of principal (in percent)		5.00%
Full debt repayment percentage of principal plus a Make-Whole Amount (in percent)		100.00%
American Assets Trust, L.P. | Senior Notes, Series A | Note Purchase Agreement
Debt Instrument [Line Items]
Face amount of debt		150,000,000
Stated Interest Rate		4.00%
American Assets Trust, L.P. | Senior Notes, Series B | Note Purchase Agreement
Debt Instrument [Line Items]
Face amount of debt		100,000,000
Stated Interest Rate		4.00%
American Assets Trust, L.P. | Senior Notes, Series C | Note Purchase Agreement
Debt Instrument [Line Items]
Face amount of debt		100,000,000
Stated Interest Rate		5.00%
American Assets Trust, L.P. | Unsecured line of credit | Amended and Restated Credit Facility | Revolving Credit Facility
Debt Instrument [Line Items]
Revolving credit facility borrowing limit, maximum borrowing capacity	250,000,000
Debt extension options	2
Debt Instrument, Extension Term	6 months
American Assets Trust, L.P. | Unsecured line of credit | Amended and Restated Credit Facility | London Interbank Offered Rate (LIBOR) | Revolving Credit Facility
Debt Instrument [Line Items]
Debt Instrument, Description of Variable Rate Basis	LIBOR
American Assets Trust, L.P. | Unsecured line of credit | Amended and Restated Credit Facility | Base Rate
Debt Instrument [Line Items]
Debt Instrument, Description of Variable Rate Basis	base rate
Debt Instrument, Variable Rate Basis, One	prime rate
Debt Instrument, Variable Rate Basis, Two	federal funds rate
Debt Instrument, Variable Rate Basis, Three	Eurodollar
American Assets Trust, L.P. | Unsecured term loan | Amended and Restated Credit Facility
Debt Instrument [Line Items]
Revolving credit facility borrowing limit, maximum borrowing capacity	100,000,000
Debt extension options	3
Debt Instrument, Extension Term	12 months
Unsecured line of credit			$20,000,000
American Assets Trust, L.P. | Minimum | Amended and Restated Credit Facility | Base Rate | Revolving Credit Facility
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.35%
American Assets Trust, L.P. | Minimum | Unsecured line of credit | Amended and Restated Credit Facility | London Interbank Offered Rate (LIBOR) | Revolving Credit Facility
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.35%
American Assets Trust, L.P. | Minimum | Unsecured term loan | Amended and Restated Credit Facility | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.30%
American Assets Trust, L.P. | Minimum | Unsecured term loan | Amended and Restated Credit Facility | Base Rate
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.30%
American Assets Trust, L.P. | Maximum | Amended and Restated Credit Facility | Base Rate | Revolving Credit Facility
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.95%
American Assets Trust, L.P. | Maximum | Unsecured line of credit | Amended and Restated Credit Facility | London Interbank Offered Rate (LIBOR) | Revolving Credit Facility
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.95%
American Assets Trust, L.P. | Maximum | Unsecured term loan | Amended and Restated Credit Facility | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.90%
American Assets Trust, L.P. | Maximum | Unsecured term loan | Amended and Restated Credit Facility | Base Rate
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.90%
American Assets Trust, L.P. | Interest Rate Swap | Cash Flow Hedging
Debt Instrument [Line Items]
Interest rate on derivative	3.08%

DEBT_Summary_of_Total_Secured_

DEBT - Summary of Total Secured Notes Payable Outstanding (Details) (American Assets Trust, L.P., USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015		Dec. 31, 2014
Shops At Kalakaua
Debt Instrument [Line Items]
Stated Interest Rate	0.00%	[1],[2]
Stated Maturity Date	1-May-15	[1],[2]
The Land Mark at One Market
Debt Instrument [Line Items]
Stated Interest Rate	5.61%	[1],[3]
Stated Maturity Date	5-Jul-15	[1],[3]
Del Monte Center
Debt Instrument [Line Items]
Stated Interest Rate	0.00%	[1],[4]
Stated Maturity Date	8-Jul-15	[1],[4]
First And Main
Debt Instrument [Line Items]
Stated Interest Rate	3.97%	[1]
Stated Maturity Date	1-Jul-16	[1]
Imperial Beach Gardens
Debt Instrument [Line Items]
Stated Interest Rate	6.16%	[1]
Stated Maturity Date	1-Sep-16	[1]
Mariners Point
Debt Instrument [Line Items]
Stated Interest Rate	6.09%	[1]
Stated Maturity Date	1-Sep-16	[1]
South Bay Marketplace
Debt Instrument [Line Items]
Stated Interest Rate	5.48%	[1]
Stated Maturity Date	10-Feb-17	[1]
Waikiki Beach Walk - Retail
Debt Instrument [Line Items]
Stated Interest Rate	5.39%	[1]
Stated Maturity Date	1-Jul-17	[1]
Solana Beach Corporate Centre Three To Four
Debt Instrument [Line Items]
Stated Interest Rate	6.39%	[5]
Stated Maturity Date	1-Aug-17	[5]
Loma Palisades
Debt Instrument [Line Items]
Stated Interest Rate	6.09%	[1]
Stated Maturity Date	1-Jul-18	[1]
One Beach Street
Debt Instrument [Line Items]
Stated Interest Rate	3.94%	[1]
Stated Maturity Date	1-Apr-19	[1]
Torrey Reserve North Court
Debt Instrument [Line Items]
Stated Interest Rate	7.22%	[5]
Stated Maturity Date	1-Jun-19	[5]
Torrey Reserve
Debt Instrument [Line Items]
Stated Interest Rate	6.36%	[5]
Stated Maturity Date	1-Jun-20	[5]
Solana Beach Corporate Centre One To Two
Debt Instrument [Line Items]
Stated Interest Rate	5.91%	[5]
Stated Maturity Date	1-Jun-20	[5]
Solana Beach Towne Centre
Debt Instrument [Line Items]
Stated Interest Rate	5.91%	[5]
Stated Maturity Date	1-Jun-20	[5]
City Center Bellevue
Debt Instrument [Line Items]
Stated Interest Rate	3.98%	[1]
Stated Maturity Date	1-Nov-22	[1]
Secured Debt
Debt Instrument [Line Items]
Total	$718,253		$819,983
Unamortized fair value adjustment	-6,444		-7,172
Total Debt Outstanding	711,809		812,811
Period of amortization schedule (in years)	30 years
Secured Debt | Shops At Kalakaua
Debt Instrument [Line Items]
Secured notes payable, Principal Balance	0	[1],[2]	19,000	[1],[2]
Secured Debt | The Land Mark at One Market
Debt Instrument [Line Items]
Secured notes payable, Principal Balance	133,000	[1],[3]	133,000	[1],[3]
Secured Debt | Del Monte Center
Debt Instrument [Line Items]
Secured notes payable, Principal Balance	0	[1],[4]	82,300	[1],[4]
Secured Debt | First And Main
Debt Instrument [Line Items]
Secured notes payable, Principal Balance	84,500	[1]	84,500	[1]
Secured Debt | Imperial Beach Gardens
Debt Instrument [Line Items]
Secured notes payable, Principal Balance	20,000	[1]	20,000	[1]
Secured Debt | Mariners Point
Debt Instrument [Line Items]
Secured notes payable, Principal Balance	7,700	[1]	7,700	[1]
Secured Debt | South Bay Marketplace
Debt Instrument [Line Items]
Secured notes payable, Principal Balance	23,000	[1]	23,000	[1]
Secured Debt | Waikiki Beach Walk - Retail
Debt Instrument [Line Items]
Secured notes payable, Principal Balance	130,310	[1]	130,310	[1]
Secured Debt | Solana Beach Corporate Centre Three To Four
Debt Instrument [Line Items]
Secured notes payable, Principal Balance	36,257	[5]	36,376	[5]
Secured Debt | Loma Palisades
Debt Instrument [Line Items]
Secured notes payable, Principal Balance	73,744	[1]	73,744	[1]
Secured Debt | One Beach Street
Debt Instrument [Line Items]
Secured notes payable, Principal Balance	21,900	[1]	21,900	[1]
Secured Debt | Torrey Reserve North Court
Debt Instrument [Line Items]
Secured notes payable, Principal Balance	20,995	[5]	21,075	[5]
Secured Debt | Torrey Reserve
Debt Instrument [Line Items]
Secured notes payable, Principal Balance	7,074	[5]	7,101	[5]
Secured Debt | Solana Beach Corporate Centre One To Two
Debt Instrument [Line Items]
Secured notes payable, Principal Balance	11,255	[5]	11,302	[5]
Secured Debt | Solana Beach Towne Centre
Debt Instrument [Line Items]
Secured notes payable, Principal Balance	37,518	[5]	37,675	[5]
Secured Debt | City Center Bellevue
Debt Instrument [Line Items]
Secured notes payable, Principal Balance	$111,000	[1]	$111,000	[1]
[1]	Interest only.
[2]	Loan repaid in full, without premium or penalty, on February 2, 201
[3]	Loan repaid in full, without premium or penalty, on April 6, 2015
[4]	Loan repaid in full, without premium or penalty, on February 6, 2015.
[5]	Principal payments based on a 30-year amortization schedule.

DEBT_Summary_of_Total_Unsecure

DEBT - Summary of Total Unsecured Notes Payable Outstanding (Details) (USD $)	3 Months Ended	0 Months Ended	3 Months Ended
	Mar. 31, 2015	Aug. 19, 2014	Mar. 31, 2014	Dec. 31, 2014
	Extension_Option
Debt Instrument [Line Items]
Unsecured notes payable	$350,000,000			$250,000,000
American Assets Trust, L.P.
Debt Instrument [Line Items]
Unsecured notes payable	350,000,000			250,000,000
American Assets Trust, L.P. | Term Loan
Debt Instrument [Line Items]
Unsecured notes payable				100,000,000
Stated Maturity Date	9-Jan-19
Debt extension options	3
American Assets Trust, L.P. | Senior Guaranteed Notes, Series A
Debt Instrument [Line Items]
Unsecured notes payable	150,000,000			150,000,000
Stated Interest Rate	4.04%
Stated Maturity Date	31-Oct-21
American Assets Trust, L.P. | Senior Guaranteed Notes, Series B
Debt Instrument [Line Items]
Unsecured notes payable	100,000,000			0
Stated Interest Rate	4.45%
Stated Maturity Date	2-Feb-25
Interest Rate Swap | American Assets Trust, L.P.
Debt Instrument [Line Items]
Derivative fixed interest rate (in percent)	3.08%
Forward Contracts | American Assets Trust, L.P.
Debt Instrument [Line Items]
Derivative contract term		7 years
Gain on derivative settlement			$1,600,000
Effective rate of debt instrument (in percent)	3.88%

PARTNERS_CAPITAL_OF_AMERICAN_A1

PARTNERS CAPITAL OF AMERICAN ASSETS TRUST, L.P. (Details)	3 Months Ended
	Mar. 31, 2015
Common Shares
Capital Unit [Line Items]
Conversion of operating partnership units (in shares)	5,741
American Assets Trust, L.P.
Capital Unit [Line Items]
Noncontrolling common units	17,899,516
Percentage of ownership interests classified as noncontrolling	29.10%
American Assets Trust, L.P. | Common Shares
Capital Unit [Line Items]
Conversion of operating partnership units (in shares)	5,741

EQUITY_OF_AMERICAN_ASSETS_TRUS2

EQUITY OF AMERICAN ASSETS TRUST, INC. (Details) (USD $)	3 Months Ended		0 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	6-May-13	Mar. 09, 2015	Sep. 12, 2014
			Agent
Equity [Line Items]
Noncash compensation expense	$900,000	$500,000
Unrecognized compensation expense	3,900,000
Weighted average unvested shares outstanding	246,672	406,856
At The Market Equity Program
Equity [Line Items]
Number of sales agents			4
Aggregate offering price of common share			150,000,000
Remaining capacity to issue	30,100,000
Common shares issued (in shares)	53,800
Gross proceeds from issuance of common stock	2,288,000
ICW Inc | Board of Directors Chairman | Private Placement
Equity [Line Items]
Common shares issued (in shares)				200,000	400,000
Share price (in dollars per share)				$40.54	$33.76
Gross proceeds from issuance of common stock				$8,100,000	$13,500,000
Operating Partnership Units
Equity [Line Items]
Antidilutive securities excluded from computation of EPS	246,672	406,856

EQUITY_OF_AMERICAN_ASSETS_TRUS3

EQUITY OF AMERICAN ASSETS TRUST, INC. - ATM Equity Program (Details) (USD $)	3 Months Ended
In Thousands, except Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Equity [Line Items]
Proceeds, net	$10,272	$46,926
At The Market Equity Program
Equity [Line Items]
Number of shares of common stock issued through ATM program	53,800
Weighted average price per share	$42.54
Proceeds, gross	2,288
Proceeds, net	2,164
Commissions | At The Market Equity Program
Equity [Line Items]
Payments of stock issuance costs	-23
Other Offering Costs | At The Market Equity Program
Equity [Line Items]
Payments of stock issuance costs	($101)

EQUITY_OF_AMERICAN_ASSETS_TRUS4

EQUITY OF AMERICAN ASSETS TRUST, INC. - Dividends Declare and Paid on Shares on Common Stock and Noncontrolling Common Units (Details) (USD $)	3 Months Ended
	Mar. 31, 2015
Equity [Abstract]
Dividends Period	First Quarter 2015
Amount per Share/Unit	$0.23
Dividends Period Covered	January 1, 2015 to March 31, 2015
Dividends Payable, Date to be Paid	27-Mar-15

EQUITY_OF_AMERICAN_ASSETS_TRUS5

EQUITY OF AMERICAN ASSETS TRUST, INC. - Summary of Activity of Restricted Stock Awards (Details) (Restricted Stock Units (RSUs), USD $)	3 Months Ended
	Mar. 31, 2015
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Nonvested, Beginning, Shares	493,539
Granted, Shares	0
Vested, Shares	-308,587
Forfeited, Shares	0
Nonvested, End of year, shares	184,952
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Nonvested, Beginning, Weighted Average Grant Date Fair Value	$22.01
Granted, Weighted Average Grant Date Fair Value	$0
Vested, Weighted Average Grant Date Fair Value	$15.36
Forfeited, Weighted Average Grant Date Fair Value	$0
Nonvested, End of Year, Weighted Average Grant Date Fair Value	$33.10

EQUITY_OF_AMERICAN_ASSETS_TRUS6

EQUITY OF AMERICAN ASSETS TRUST, INC. - Computation of Basic and Diluted EPS (Details) (USD $)	3 Months Ended
In Thousands, except Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Equity [Abstract]
Net income from operations	$11,379	$6,658
Less: Net income attributable to restricted shares	-43	-70
Less: Income from continuing operations attributable to unitholders in the Operating Partnership	-3,309	-1,986
Net income attributable to common stockholders—basic	8,027	4,602
Income from operations attributable to American Assets Trust, Inc. common stockholders—basic	8,027	4,602
Net income attributable to common stockholders-diluted	$11,336	$6,588
Weighted average common shares outstanding-basic	43,419,762	40,582,792
Effect of dilutive securities-conversion of Operating Partnership units	17,901,685	17,909,681
Weighted average common shares outstanding - diluted	61,321,447	58,492,473
Earnings per common share, basic	$0.18	$0.11
Earnings per common share, diluted	$0.18	$0.11

INCOME_TAXES_Details

INCOME TAXES (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Deferred tax liability	($219)		($219)
Income tax expense (benefit)	$84	$112

COMMITMENTS_AND_CONTINGENCIES_1

COMMITMENTS AND CONTINGENCIES (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
	Property
Commitment And Contingencies [Line Items]
Termination payment	$6.60
Percentage, partner's common units	50.00%
Number of consolidated properties located in Southern California	12
Maximum percentage of total revenue provided by any single tenant	10.00%	10.00%
The Land Mark at One Market
Commitment And Contingencies [Line Items]
Number of lease extension options	3
Years, lease extension options length (in years)	5 years
Quicksilver
Commitment And Contingencies [Line Items]
Percent annual lease amount increase (in percent)	3.40%
Waikiki Beach Walk - Retail
Commitment And Contingencies [Line Items]
Property management fee, percent (in percent)	3.00%
Outrigger Hotels
Commitment And Contingencies [Line Items]
Property management fee, percent (in percent)	6.00%
Number of calendar months termination fee is based	2 months
Maximum percentage of hotel's fiscal year gross revenues paid for aggregate yearly management fee	3.50%
Previous months of management fees	12 months
Hotel management agreement default penalty factor of previous twelve months of management fees in first 11 years of term	8
Years in hotel management agreement term	11 years
Hotel management agreement default penalty factor of previous twelve months of management fees in twelfth year of term	4
Hotel management agreement default penalty factor of previous twelve months of management fees in thirteenth year of term	3
Hotel management agreement default penalty factor of previous twelve months of management fees in fourteenth year of term	2
Hotel management agreement default penalty factor of previous twelve months of management fees in fifteenth year of term	1
Outrigger Hotels | Future Year Period One
Commitment And Contingencies [Line Items]
Years in hotel management agreement term	15 years
Outrigger Hotels | Future Year Period Two
Commitment And Contingencies [Line Items]
Years in hotel management agreement term	14 years
Outrigger Hotels | Future Year Period Three
Commitment And Contingencies [Line Items]
Years in hotel management agreement term	13 years
Outrigger Hotels | Future Year Period Four
Commitment And Contingencies [Line Items]
Years in hotel management agreement term	12 years
Outrigger Hotels | Maximum
Commitment And Contingencies [Line Items]
Property management fee, percent (in percent)	3.00%
Wbw Hotel Lessee Llc
Commitment And Contingencies [Line Items]
Years of contract	20 years
Percentage of hotel occupancy gross revenue paid for program fee	4.00%
Wbw Hotel Lessee Llc | Future Time Period Prior to 12-31-2021
Commitment And Contingencies [Line Items]
Percentage of hotel occupancy gross revenue paid for franchise royalty fee	4.00%
Wbw Hotel Lessee Llc | Future Time Period After 12-31-2021
Commitment And Contingencies [Line Items]
Percentage of hotel occupancy gross revenue paid for franchise royalty fee	5.00%
Del Monte Center | Maximum
Commitment And Contingencies [Line Items]
Years, environmental remediation length	9 years
Del Monte Center | Minimum
Commitment And Contingencies [Line Items]
Years, environmental remediation length	2 years
Total Revenues | Retail
Commitment And Contingencies [Line Items]
Percentage of total revenue provided by retail tenants	36.40%
Total Revenues | Office
Commitment And Contingencies [Line Items]
Percentage of total revenue provided by retail tenants	35.70%

COMMITMENTS_AND_CONTINGENCIES_2

COMMITMENTS AND CONTINGENCIES - Current Minimum Annual Payments under Leases (Details) (USD $)	Mar. 31, 2015		Jun. 30, 2016	Feb. 28, 2017
Operating Leased Assets [Line Items]
2015 (nine months ending December 31, 2015)	$1,986,000
2016	2,682,000	[1]
2017	2,686,000	[2]
2018	2,686,000
2019	2,686,000
Thereafter	23,856,000
Total	36,582,000
Scenario, Forecast | The Land Mark at One Market
Operating Leased Assets [Line Items]
Stated monthly lease rate			162,140
Scenario, Forecast | Waikiki Beach Walk
Operating Leased Assets [Line Items]
Stated monthly lease rate				$61,690
[1]	Lease payments on The Landmark at One Market lease will be equal to fair rental value from July 2016 through the end of the options lease term. In the table, we have shown the option lease payments for this period based on the stated rate for the month of June 2016 of $162,140.
[2]	Lease payments on the Waikiki Beach Walk lease will be equal to fair rental value from March 2017 through the end of the lease term. In the table, we have shown the lease payments for this period based on the stated rate for the month of February 2017 of $61,690.

OPERATING_LEASES_Details

OPERATING LEASES (Details)	3 Months Ended
	Mar. 31, 2015
	M
Leases [Abstract]
Years, minimum term range of office and retail leases	3 years
Years, maximum term range of office and retail leases	10 years
Months, minimum term of apartment leases	7 months
Months, maximum term of apartment leases	15 months
Future minimum rentals term, maximum	12

OPERATING_LEASES_Minimum_Futur

OPERATING LEASES - Minimum Future Rentals from Noncancelable Operating Leases (Details) (USD $)	Mar. 31, 2015
In Thousands, unless otherwise specified
Leases [Abstract]
2015 (nine months ending December 31, 2015)	$121,921
2016	149,336
2017	133,727
2018	101,180
2019	72,885
Thereafter	197,835
Total	$776,884

COMPONENTS_OF_RENTAL_INCOME_AN2

COMPONENTS OF RENTAL INCOME AND EXPENSE (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Operating Leases, Income Statement, Lease Revenue [Abstract]
Recognition of straight-line rents	$0.70	$1
Recognition of amortization of above and below market leases	$0.70	$0.60

COMPONENTS_OF_RENTAL_INCOME_AN3

COMPONENTS OF RENTAL INCOME AND EXPENSE - Component of Rental Income (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Rental Income [Line Items]
Cost reimbursement	$7,037	$6,804
Percentage rent	360	425
Hotel revenue	9,008	9,002
Other	393	419
Total rental income	62,753	60,482
Total Retail
Rental Income [Line Items]
Minimum rents	18,211	17,292
Total Office
Rental Income [Line Items]
Minimum rents	21,187	20,236
Total Multifamily
Rental Income [Line Items]
Minimum rents	4,034	3,834
Total Mixed-Use
Rental Income [Line Items]
Minimum rents	$2,523	$2,470

COMPONENTS_OF_RENTAL_INCOME_AN4

COMPONENTS OF RENTAL INCOME AND EXPENSE - Components of Rental Expenses (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Operating Leases, Income Statement, Lease Revenue [Abstract]
Rental operating	$6,281	$6,526
Hotel operating	5,645	5,553
Repairs and maintenance	2,251	2,122
Marketing	385	390
Rent	614	611
Hawaii excise tax	986	965
Management fees	458	453
Total rental expenses	$16,620	$16,620

OTHER_INCOME_EXPENSE_NET_Compo

OTHER INCOME (EXPENSE) , NET Components of Other Income (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Other Income and Expenses [Abstract]
Interest and investment income	$14	$21
Income tax benefit (expense)	-84	-112
Total other income (expense), net	($70)	($91)

RELATED_PARTY_TRANSACTIONS_Det

RELATED PARTY TRANSACTIONS (Details) (USD $)	3 Months Ended		0 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Mar. 09, 2015	Sep. 12, 2014	Jul. 01, 2014
Related Party Transaction [Line Items]
Total rental income	$62,753,000	$60,482,000
Investment in WBW CHP LLC (in percent)	47.70%
WBW CHP LLC
Related Party Transaction [Line Items]
Amount Recovered For Reimbursements Of Operating Expense For Related Party	200,000	200,000
Common Shares
Related Party Transaction [Line Items]
Common shares issued (in shares)	253,800
ICW Inc | Board of Directors Chairman
Related Party Transaction [Line Items]
Total rental income	600,000	500,000
Prepaid Insurance					400,000
Percentage of ownership interests classified as noncontrolling	34.10%
ICW Inc | Private Placement | Board of Directors Chairman
Related Party Transaction [Line Items]
Common shares issued (in shares)			200,000	400,000
Share price (in dollars per share)			$40.54	$33.76
Gross proceeds from issuance of common stock			8,100,000	13,500,000
ICW Inc | Common Shares | Board of Directors Chairman
Related Party Transaction [Line Items]
Percentage of ownership interests classified as noncontrolling	10.10%
ICW Inc | Member Units | Board of Directors Chairman
Related Party Transaction [Line Items]
Percentage of ownership interests classified as noncontrolling	24.10%
Explorer Insurance Company | Private Placement | Board of Directors Chairman
Related Party Transaction [Line Items]
Common shares issued (in shares)			200,000
Share price (in dollars per share)			$40.54
Gross proceeds from issuance of common stock			$8,100,000

SEGMENT_REPORTING_Details

SEGMENT REPORTING (Details)	3 Months Ended
	Mar. 31, 2015
	Segment
	Room
Segment Reporting [Abstract]
Number of operating segments	4
Room in mixed-use segment all-suite hotel	369

SEGMENT_REPORTING_Operating_Ac

SEGMENT REPORTING - Operating Activity Within Reportable Segments (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Segment Reporting Information [Line Items]
OPERATING INCOME	$23,244	$20,381
Total Segments' profit	43,367	41,334
Total Retail
Segment Reporting Information [Line Items]
Property revenue	24,038	22,999
Property expense	-6,000	-6,058
OPERATING INCOME	18,038	16,941
Total Office
Segment Reporting Information [Line Items]
Property revenue	23,577	22,858
Property expense	-6,821	-6,893
OPERATING INCOME	16,756	15,965
Total Multifamily
Segment Reporting Information [Line Items]
Property revenue	4,310	4,130
Property expense	-1,484	-1,427
OPERATING INCOME	2,826	2,703
Total Mixed-Use
Segment Reporting Information [Line Items]
Property revenue	14,110	13,993
Property expense	-8,363	-8,268
OPERATING INCOME	$5,747	$5,725

SEGMENT_REPORTING_Reconciliati

SEGMENT REPORTING - Reconciliation of Segment Profit to Net Income Attributable to Stockholders (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Segment Reporting [Abstract]
Total Segments' profit	$43,367	$41,334
General and administrative	-5,016	-4,612
Depreciation and amortization	-15,107	-16,341
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 unitholders in the Operating Partnership	3,309	1,986
NET INCOME ATTRIBUTABLE TO AMERICAN ASSETS TRUST, INC. STOCKHOLDERS	$8,027	$4,602

SEGMENT_REPORTING_Net_Real_Est

SEGMENT REPORTING - Net Real Estate and Secured Note Payable Balances (Details) (USD $)	Mar. 31, 2015		Dec. 31, 2014
In Thousands, unless otherwise specified
Segment Reporting Information [Line Items]
Net Real Estate	$1,806,879		$1,775,400
Secured Notes Payable	718,253	[1]	819,983	[1]
Total Retail
Segment Reporting Information [Line Items]
Net Real Estate	634,758		639,456
Secured Notes Payable	60,518	[1]	161,975	[1]
Total Office
Segment Reporting Information [Line Items]
Net Real Estate	767,271		757,854
Secured Notes Payable	425,981	[1]	426,254	[1]
Total Multifamily
Segment Reporting Information [Line Items]
Net Real Estate	210,569		182,468
Secured Notes Payable	101,444	[1]	101,444	[1]
Total Mixed-Use
Segment Reporting Information [Line Items]
Net Real Estate	194,281		195,622
Secured Notes Payable	$130,310	[1]	$130,310	[1]
[1]	Excludes unamortized fair market value adjustments of $6.4 million and $7.2 million as of March 31, 2015 and December 31, 2014, respectively.

SEGMENT_REPORTING_Capital_Expe

SEGMENT REPORTING - Capital Expenditures (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015		Mar. 31, 2014
Segment Reporting Information [Line Items]
Capital Expenditures	$44,968	[1]	$31,296	[1]
Total Retail
Segment Reporting Information [Line Items]
Capital Expenditures	935	[1]	1,506	[1]
Total Office
Segment Reporting Information [Line Items]
Capital Expenditures	14,714	[1]	7,091	[1]
Total Multifamily
Segment Reporting Information [Line Items]
Capital Expenditures	28,948	[1]	21,877	[1]
Total Mixed-Use
Segment Reporting Information [Line Items]
Capital Expenditures	$371	[1]	$822	[1]
[1]	Capital expenditures represent cash paid for capital expenditures during the period and include leasing commissions paid.

SUBSEQUENT_EVENTS_Details

SUBSEQUENT EVENTS (Details) (Senior Notes, Series C, Note Purchase Agreement, Subsequent Event, USD $)	1-May-15
Senior Notes, Series C | Note Purchase Agreement | Subsequent Event
Subsequent Event [Line Items]
Face amount of debt	$100,000,000