SEGMENT REPORTING - Reconciliation of Segment Profit to Net Income Attributable to Stockholders (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Segment Reporting [Abstract]
Total Segments' profit	$ 43,367us-gaap_GrossProfit	$ 41,334us-gaap_GrossProfit
General and administrative	(5,016)us-gaap_GeneralAndAdministrativeExpense	(4,612)us-gaap_GeneralAndAdministrativeExpense
Depreciation and amortization	(15,107)us-gaap_DepreciationAndAmortization	(16,341)us-gaap_DepreciationAndAmortization
Interest expense	11,795	13,632
Other income (expense), net	(70)us-gaap_OtherNonoperatingIncomeExpense	(91)us-gaap_OtherNonoperatingIncomeExpense
NET INCOME	11,379us-gaap_ProfitLoss	6,658us-gaap_ProfitLoss
Net income attributable to restricted shares	(43)	(70)
Net income attributable to unitholders in the Operating Partnership	3,309	1,986
NET INCOME ATTRIBUTABLE TO AMERICAN ASSETS TRUST, INC. STOCKHOLDERS	$ 8,027us-gaap_NetIncomeLoss	$ 4,602us-gaap_NetIncomeLoss

Interest Expense, Exclude Construction in Progress

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Net income attributable to restricted share.

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The current period expense charged against earnings on long-lived, physical assets not used in production, and which are not intended for resale, to allocate or recognize the cost of such assets over their useful lives; or to record the reduction in book value of an intangible asset over the benefit period of such asset; or to reflect consumption during the period of an asset that is not used in production.

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The aggregate total of expenses of managing and administering the affairs of an entity, including affiliates of the reporting entity, which are not directly or indirectly associated with the manufacture, sale or creation of a product or product line.

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Aggregate revenue less cost of goods and services sold or operating expenses directly attributable to the revenue generation activity.

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The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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Amount after tax of income (loss) attributable to redeemable noncontrolling partner in an operating partnership.

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The net amount of other income and expense amounts, the components of which are not separately disclosed on the income statement, resulting from ancillary business-related activities (that is, excluding major activities considered part of the normal operations of the business) also known as other nonoperating income (expense) recognized for the period. Such amounts may include: (a) dividends, (b) interest on securities, (c) net gains or losses on securities, (d) unusual costs, (e) gains or losses on foreign exchange transactions, and (f) miscellaneous other income and expense items.

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The consolidated profit or loss for the period, net of income taxes, including the portion attributable to the noncontrolling interest.

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