Disclosure of Compensation Related Costs, Share-based Payments [Abstract] Share-based Compensation, Allocation and Classification in Financial Statements [Abstract] Grants of common shares and options Allocated Share-based Compensation Expense Capitalized share-based compensation Employee Service Share-based Compensation, Allocation of Recognized Period Costs, Capitalized Amount Share-based compensation expense Share-based Compensation Commitments and Contingencies Disclosure [Abstract] downREIT operating partnership units, outstanding Partners' Capital Account, Units downREIT operating partnership units outstanding, fair value Operating Partnership Units Fair Value Fair value of operating partnership units at the balance sheet date. Noncash or Part Noncash Acquisitions [Table] Noncash or Part Noncash Acquisitions [Table] Business Acquisition [Axis] Business Acquisition [Axis] Business Acquisition, Acquiree [Domain] Business Acquisition, Acquiree [Domain] San Antonio Center San Antonio Center [Member] San Antonio Center Purchase option of non-controlling interest Noncash or Part Noncash Acquisitions [Line Items] Payments to Acquire Outstanding Interest Payments to Acquire Outstanding Interest Payments to acquire outstanding interest in partnership Number of downREIT units issued in connection with purchase option Number of downREIT units issued in connection with purchase option Number of downREIT units issued in connection with purchase option Summary of share-based compensation expense included in net income Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Table Text Block] Components Of Rental Income and Expense [Abstract] Components Of Rental Income And Expense [Abstract] Principal components of rental income Schedule of Component of Rental Income [Table Text Block] Schedule of Component of Rental Income [Table Text Block] Minimum rents Schedule Of Minimum Rents Components [Table TextBlock] Schedule of Minimum Rents Components [Table Text Block] COMMITMENTS AND CONTINGENCIES Commitments and Contingencies Disclosure [Text Block] Schedule of Minimum Rents [Table] Schedule of Minimum Rents [Table] Schedule of Minimum Rents [Table] Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets, Major Class Name [Domain] Finite-Lived Intangible Assets, Major Class Name [Domain] Amortization of above market leases Above Market Leases [Member] Amortization of below market leases BelowMarketLease [Member] BelowMarketLease [Member] Minimum Rent [Line Items] Minimum Rent [Line Items] Minimum Rent [Line Items] Straight-line rents Straight Line Rent Amortization of above and below market leases Amortization of above and below Market Leases Earnings Per Share [Abstract] Weighted average unvested shares outstanding Incremental Common Shares Attributable to Participating Nonvested Shares with Non-forfeitable Dividend Rights Anti-dilutive stock options Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Cumulative convertible preferred shares, dividend rate Preferred Stock, Dividend Rate, Percentage Stockholders' Equity Note [Abstract] Statement [Table] Schedule of Stock by Class [Table] Preferred Units by type [Axis] Preferred Units by Name [Axis] Preferred Units by type Preferred Units, Class [Domain] Depository Shares Depository Shares [Member] Depository Shares Class of Stock [Axis] Class of Stock [Axis] Class of Stock Class of Stock [Domain] 5.0% Series C Cumulative Redeemable Preferred 5.0% Series C Cumulative Redeemable Preferred [Member] Five point Zero Percentage Series C Redeemable Convertible Preferred Stock [Member] Equity Components [Axis] Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] Common Shares Common Stock [Member] Preferred Shares Preferred Stock [Member] Sale of Stock [Axis] Sale of Stock [Axis] Sale of Stock [Domain] Sale of Stock [Domain] At The Market Equity Program At The Market Equity Program [Member] At The Market Equity Program [Member] Stock Issuance Costs by Type [Axis] Stock Issuance Costs by Type [Axis] Stock Issuance Costs by Type [Axis] Stock Issuance Costs by Type [Domain] Stock Issuance Costs by Type [Domain] [Domain] for Stock Issuance Costs by Type [Axis] Commissions Commissions [Member] Commissions [Member] Other offering costs Other Offering Costs [Member] Other Offering Costs [Member] Class of Stock [Line Items] Class of Stock [Line Items] Aggregate offering price of common shares Aggregate Offering Price Of Common Share Maximum aggregate offering price of common shares. Shares issued (in shares) Stock Issued During Period, Shares, New Issues Weighted average price per common share Weighted Average Price Per Common Share Weighted average price per common share Net cash proceeds of common stock Proceeds from Issuance of Common Stock Payments of stock issuance costs Payments of Stock Issuance Costs Remaining capacity to issue Remaining Capacity To Issue Remaining $ Capacity Of Shares To Issue Preferred shares, percentage Preferred shares, par value Preferred Stock, Par or Stated Value Per Share Preferred shares, liquidation preference Preferred Stock, Liquidation Preference Per Share Net cash proceeds of preferred shares Proceeds from Issuance of Preferred Stock and Preference Stock Statement of Cash Flows [Abstract] OPERATING ACTIVITIES Net Cash Provided by (Used in) Operating Activities [Abstract] Net income Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Adjustments to reconcile net income to net cash provided by operating activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Depreciation and amortization Adjustment Depreciation And Amortization The cash flow addback for the non-cash expense of depreciation and amortization including depreciation and amortization related to discontinued operations. Gain on sale of real estate and change in control of interests, net Gain (loss) on change in control of interests and sale of real estate Gain (loss) on change in control of interests and sale of real estate Loss (income) from real estate partnerships Income (Loss) from Equity Method Investments Other, net Other Noncash Income (Expense) Changes in assets and liabilities, net of effects of acquisitions and dispositions: Increase (Decrease) in Operating Capital [Abstract] Increase in accounts receivable, net Increase (Decrease) in Accounts and Other Receivables Increase in prepaid expenses and other assets Increase (Decrease) in Prepaid Expense and Other Assets Increase in accounts payable and accrued expenses Increase (Decrease) in Accounts Payable and Accrued Liabilities Increase (decrease) in security deposits and other liabilities Increase Decrease In Security Deposits And Other Liabilities The net change in Security Deposits And Other Liabilities which includes security deposits, deferred revenue and prepaid rent. Also includes liabilities not individually reported in the financial statements, or not separately disclosed in notes. Net cash provided by operating activities Net Cash Provided by (Used in) Operating Activities INVESTING ACTIVITIES Net Cash Provided by (Used in) Investing Activities [Abstract] Acquisition of real estate Payments to Acquire Real Estate Capital expenditures - development and redevelopment Capital Expenditures Development Redevelopment Payments to develop or redevelop real estate assets is the process of adding improvements on or to a parcel of land. Such improvements may include drainage, utilities, subdividing, access, buildings, and any combination of these elements. In addition, the cash outflow from construction costs to date on capital projects that have not been completed and assets being constructed that are not ready to be placed into service. Capital expenditures - other Payments for Capital Improvements Proceeds from sale of real estate and real estate partnership interests Proceeds from the sale of real estate and real estate partnership interests Proceeds from the sale of real estate and real estate partnership interests Investment in real estate partnerships Payments to Acquire Interest in Subsidiaries and Affiliates Distribution from real estate partnership in excess of earnings Proceeds from Distributions Received from Real Estate Partnerships Leasing costs Increase (Decrease) in Lease Acquisition Costs (Issuance) repayment of mortgage and other notes receivable, net Issuance And Repayments Of Mortgage And Other Notes Receivable Net The cash outflow from the issuance and purchase of receivables arising from the mortgage note on real estate and other notes receivable, net of repayments. Net cash used in investing activities Net Cash Provided by (Used in) Investing Activities FINANCING ACTIVITIES Net Cash Provided by (Used in) Financing Activities [Abstract] Net borrowings (repayment) under revolving credit facility, net of costs Proceeds from (Repayments of) Lines of Credit Issuance of senior notes, net of costs Proceeds from Issuance of Senior Long-term Debt Repayment of mortgages and capital leases Repayments of Long-term Debt, Long-term Capital Lease Obligations, and Capital Securities Issuance of common shares, net of costs Issuance of preferred shares, net of costs Dividends paid to common and preferred shareholders Dividends Paid To Common And Preferred Shareholders The cash outflow from distribution of an entity's earnings to common and preferred stockholders. Shares withheld for employee taxes Payments Related to Tax Withholding for Share-based Compensation Contributions from noncontrolling interests Proceeds from Noncontrolling Interests Distributions to and redemptions of noncontrolling interests PaymentsOfDividendsAndRedemptionsMinorityInterest The cash outflow for the return on capital for noncontrolled interest in the entity and cash outflow during the period for redemptions of noncontrolling interests. Net cash provided by financing activities Net Cash Provided by (Used in) Financing Activities (Decrease) increase in cash and cash equivalents Cash and Cash Equivalents, Period Increase (Decrease) Cash and cash equivalents at beginning of year Cash and Cash Equivalents, at Carrying Value Cash and cash equivalents at end of period Accounting Policies [Abstract] Total interest costs incurred Interest Costs Incurred Interest capitalized Interest Costs Capitalized Interest expense Interest Expense Cash paid for interest, net of amounts capitalized Interest Paid, Net Cash paid for income taxes Income Taxes Paid, Net Mortgage loans refinanced Refinance of mortgage loan Refinance of mortgage loan Mortgage loans assumed with acquisition Noncash or Part Noncash Acquisition, Debt Assumed DownREIT operating partnership units issued with acquisition of noncontrolling interest Value of downREIT Operating Partnership Units Issued With Acq. of Noncontrolling Interest Value of downREIT Operating Partnership Units Issued With Acq. of Noncontrolling Interest DownREIT operating partnership units redeemed for common shares Redemptionofoperatingpartnershipunitsforcommonshares Redemption of operating partnership units for common shares Shares issued under dividend reinvestment plan Dividends Reinvested in Noncash Financing Transaction Dividends reinvested in noncash financing transaction Nature Of Operations [Abstract] Nature Of Operations [Abstract] Number of real estate properties Number of Real Estate Properties Minimum percentage of taxable income distributed to shareholders Minimum Percentage Of Taxable Income Distributed To Shareholders Minimum percentage of taxable income distributed to shareholders. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Significant Accounting Policies [Text Block] Real Estate [Abstract] Schedule of Significant Acquisitions [Table] Schedule of Business Acquisitions, by Acquisition [Table] Debt Instrument [Axis] Debt Instrument [Axis] Debt Instrument Debt Instrument, Name [Domain] Primestor Primestor [Member] Primestor [Member] Long-term Debt, Type [Axis] Long-term Debt, Type [Axis] Long-term Debt, Type Long-term Debt, Type [Domain] Mortgage loan Mortgages [Member] La Alameda La Alameda [Member] La Alameda [Member] Name of Property [Axis] Name of Property [Axis] Name of Property [Domain] Name of Property [Domain] Hastings Ranch Plaza Hastings Ranch Plaza [Member] Hastings Ranch Plaza Riverpoint Center Riverpoint Center [Member] Riverpoint Center [Member] Assembly Row Assembly Square Market Place Assembly Row [Member] Assembly Square Market Place Assembly Row [Member] Mixed-use property located in Berkeley, California 1700-1730 4th Street [Member] 1700-1730 4th Street [Member] Azalea Azalea [Member] Azalea [Member] Bell Gardens Bell Gardens Centers [Member] Bell Gardens Centers [Member] Olivo at Mission Hills Olivo at Mission Hills [Member] Olivo at Mission Hills [Member] Plaza Del Sol Plaza Del Sol [Member] Plaza Del Sol [Member] Plaza Pacoima Plaza Pacoima [Member] Plaza Pacoima [Member] Sylmar Towne Center Sylmar Towne Center [Member] Sylmar Town Center 150 Post Street 150 Post Street [Member] 150 Post Street [Member] North Lake Commons North Lake Commons [Member] North Lake Commons [Member] Balance Sheet Location [Axis] Balance Sheet Location [Axis] Balance Sheet Location [Domain] Balance Sheet Location [Domain] Other Assets Other Assets [Member] Other Liabilities Other Liabilities [Member] Lease intangibles Leases, Acquired-in-Place [Member] Lease liabilities Lease liabilities [Member] Lease Liabilities [Member] Above market leases Legal Entity [Axis] Legal Entity [Axis] Entity [Domain] Entity [Domain] FRIT/Primestor JV FRIT/Primestor JV [Member] FRIT/Primestor JV Property, Plant and Equipment, Type [Axis] Property, Plant and Equipment, Type [Axis] Property, Plant and Equipment, Type [Domain] Property, Plant and Equipment, Type [Domain] Land Land [Member] Condominiums Condominiums [Member] Condominiums [Member] Business Acquisitions and Dispositions Business Acquisition [Line Items] Square footage Area of Real Estate Property Purchase price Purchase price of real estate acquisition Purchase price of real estate acquisition Net assets acquired Finite-lived Intangible Assets Acquired Net assets acquired allocated to below market leases Below Market Lease, Acquired Number of ground lessees Number of Members With Purchase Options Number of Members With Purchase Options Proceeds from sale Sales of Real Estate Gain (Loss) on Sale of Properties Gain (Loss) on Sale of Properties Gain on sale of real estate, net Gain (Loss) on Sale of Properties, Net of Applicable Income Taxes Gross value Real estate acquisition, gross value Real estate acquisition, gross value Ownership interest Variable Interest Entity, Qualitative or Quantitative Information, Ownership Percentage Taxes related to the sale of condominiums Gain (Loss) on Sale of Properties, Applicable Income Taxes Contributions from noncontrolling interests Noncontrolling Interest in Variable Interest Entity Equity Method Investments Equity Method Investment, Ownership Percentage Purchase price of equity method investment Purchase price of equity method investment Purchase price of equity method investment Receivable recognized on the sale of condominiums Accounts Receivable, Gross Mortgage Debt Mortgage Loan on Unconsolidated Real Estate Property Mortgage Loan on Unconsolidated Real Estate Property Our share of mortgage debt Our share of unconsolidated mortgage debt Our share of unconsolidated mortgage debt Asset Acquisitions, Pro Forma depreciation and amortization Asset Acquisitions, Pro Forma depreciation and amortization Asset Acquisitions, Pro Forma depreciation and amortization Asset Acquisitions Pro Forma Revenue Asset Acquisitions Pro Forma Revenue Pro forma revenue as if asset acquisitions happened at the beginning of the period. Asset Acquisitions, Pro Forma Net Inome (Loss) Asset Acquisitions, Pro Forma Net Inome (Loss) Pro Forma net inome (loss) as if the acquisitions had occured at the beginning of the period. Supplemental disclosures related to the Consolidated Statements Of Cash Flows Schedule of Cash Flow, Supplemental Disclosures [Table Text Block] REAL ESTATE Real Estate Acquisitions Dispositions Text Block Disclosure of real estate acquisitions and dispositions, and at year end, a summary of our real estate investments and related encumbrances. Statement of Financial Position [Abstract] Statement [Table] Statement [Table] 5.417% Series 1 Cumulative Convertible Preferred 5.417% Series 1 Cumulative Convertible Preferred [Member] Five point Four One Seven Percentage Series One Cumulative Convertible Preferred Stock [Member] Statement [Line Items] Statement [Line Items] Operating real estate, consolidated variable interest entities Operating Real Estate From Consolidated Variable Interest Entities Operating real estate balances from variable interest entities, or VIEs, for the periods presented. Mortgages payable, consolidated variable interest entities Mortgage Payable From Consolidated Variable Interest Entities Mortgages payable balances from variable interest entities, or VIEs, for the periods presented. Accumulated depreciation and amortization, consolidated variable interest entities Accumulated depreciation and amortization, consolidated variable interest entities Accumulated depreciation and amortization related to real estate, Consolidated Variable Interest Entities. Preferred shares, authorized Preferred Stock, Shares Authorized Preferred shares, shares issued Preferred Stock, Shares Issued Preferred shares, shares outstanding Preferred Stock, Shares Outstanding Common shares of beneficial interest, par value Common Stock, Par or Stated Value Per Share Common shares of beneficial interest, shares authorized Common Stock, Shares Authorized Common shares of beneficial interest, shares issued Common Stock, Shares, Issued Common shares of beneficial interest, shares outstanding Common Stock, Shares, Outstanding Fair Value Disclosures [Abstract] Fair Value Measurements, Recurring and Nonrecurring [Table] Fair Value Measurements, Recurring and Nonrecurring [Table] Derivative Instrument Derivative Instrument [Axis] Derivative, Name [Domain] Derivative Contract [Domain] Interest Rate Swap Interest Rate Swap [Member] Measurement Frequency [Axis] Measurement Frequency [Axis] Fair Value, Measurement Frequency [Domain] Fair Value, Measurement Frequency [Domain] Fair Value, Measurements, Recurring Fair Value, Measurements, Recurring [Member] Fair Value, Hierarchy [Axis] Fair Value, Hierarchy [Axis] Fair Value Hierarchy [Domain] Fair Value Hierarchy [Domain] Level 1 Fair Value, Inputs, Level 1 [Member] Level 2 Fair Value, Inputs, Level 2 [Member] Level 3 Fair Value, Inputs, Level 3 [Member] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Fair value of interest rate swaps Derivative Liability Debt Instruments [Abstract] DEBT Debt Disclosure [Text Block] COMPONENTS OF RENTAL INCOME Operating Leases Revenue And Expense Text Block The principal components of rental income and/or rental expense recognized for the period. Scenario [Axis] Scenario [Axis] Scenario, Unspecified [Domain] Scenario, Unspecified [Domain] INCOME FROM CONTINUING OPERATIONS Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest Less: Preferred share dividends Preferred Stock Dividends, Income Statement Impact Less: Income from continuing operations attributable to noncontrolling interests Net income attributable to noncontrolling interests, net of amounts from gain on real estate Net income attributable to noncontrolling interests, net of amounts from gain on real estate Less: Earnings allocated to unvested shares Earnings Allocated To Unvested Shares Earnings allocated to unvested shares Income from continuing operations available for common shareholders Income Loss From Continuing Operations Available For Common Shareholders This element represents the income or loss from continuing operations attributable to the parent after earnings allocated to unvested shares and adjustments for dividends on preferred stock. Gain on sale of real estate and change in control of interests, net Gain (loss) on change in control of interests and sale of real estate, net Gain (loss) on change in control of interests and sale of real estate, net of noncontrolling interests Net income available for common shareholders, basic and diluted Net income available for common shareholders, basic and diluted Net income after adjustments for dividends on preferred stock and earnings allocated to unvested shares. Weighted average common shares outstanding—basic Weighted Average Number of Shares Outstanding, Basic Stock options Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements Weighted average common shares outstanding—diluted Weighted Average Number of Shares Outstanding, Diluted Earnings Per Common Share, Basic Earnings Per Share, Basic Earnings per common share, diluted Earnings Per Share, Diluted Income from continuing operations attributable to the Trust Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent SHARE-BASED COMPENSATION PLANS Disclosure of Compensation Related Costs, Share-based Payments [Text Block] Summary of carrying amount and fair value of financial instruments Schedule of Carrying Values and Estimated Fair Values of Debt Instruments [Table Text Block] Summary of financial liabilities measured at fair value on a recurring basis Fair Value, Liabilities Measured on Recurring Basis [Table Text Block] Basis of Presentation Basis of Accounting, Policy [Policy Text Block] Principles of Consolidation Consolidation, Policy [Policy Text Block] Use of Estimates Use of Estimates, Policy [Policy Text Block] Revenue Recognition Revenue Recognition, Percentage-of-Completion Method [Policy Text Block] Recently Issued Accounting Pronouncements New Accounting Pronouncements, Policy [Policy Text Block] Recently Adopted Accounting Pronouncements New Accounting Pronouncements and Changes in Accounting Principles [Text Block] BUSINESS AND ORGANIZATION Nature of Operations [Text Block] Components of Rental Income [Table] Components of Rental Income [Table] Components of Rental Income [Table] Property Subject to or Available for Operating Lease Property Subject to or Available for Operating Lease [Axis] Property Subject to or Available for Operating Lease [Domain] Property Subject to or Available for Operating Lease [Domain] Retail and Commercial Commercial Real Estate [Member] Residential Residential Real Estate [Member] Minimum rents Operating Leases, Income Statement, Minimum Lease Revenue Cost reimbursement Tenant Reimbursements Percentage rents Operating Leases, Income Statement, Percentage Revenue Other Other Rental Income This element represents other rental revenue earned during the period. Total rental income Operating Leases, Income Statement, Lease Revenue Income Statement [Abstract] REVENUE Revenues [Abstract] Rental income Other property income Other Real Estate Revenue Mortgage interest income Revenue Mortgage Interest Interest income earned from mortgage notes receivable. Total revenue Revenues EXPENSES Operating Expenses [Abstract] Rental expenses Direct Costs of Leased and Rented Property or Equipment Real estate taxes Real Estate Tax Expense General and administrative General and Administrative Expense Depreciation and amortization Depreciation, Depletion and Amortization, Nonproduction Total operating expenses Operating Expenses OPERATING INCOME Operating Income (Loss) Other interest income Interest Income, Other Interest expense (Loss) income from real estate partnerships INCOME FROM CONTINUING OPERATIONS Gain on sale of real estate and change in control of interests, net NET INCOME Net income attributable to noncontrolling interests Net Income (Loss) Attributable to Noncontrolling Interest NET INCOME ATTRIBUTABLE TO THE TRUST Net Income (Loss) Attributable to Parent Dividends on preferred shares NET INCOME AVAILABLE FOR COMMON SHAREHOLDERS Net Income (Loss) Available to Common Stockholders, Basic EARNINGS PER COMMON SHARE, BASIC: Earnings Per Share, Basic [Abstract] Net income available for common shareholders Weighted average number of common shares EARNINGS PER COMMON SHARE, DILUTED: Earnings Per Share, Diluted [Abstract] Net income available for common shareholders Weighted average number of common shares COMPREHENSIVE INCOME Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest COMPREHENSIVE INCOME ATTRIBUTABLE TO THE TRUST Comprehensive Income (Loss), Net of Tax, Attributable to Parent Debt Disclosure [Abstract] Mortgage Loans Assumed in Acquisition Mortgage loans assumed in acquisition [Table Text Block] Mortgage loans assumed in acquisition [Table Text Block] Dividends [Abstract] Dividends [Abstract] Dividends declared per common share Common Stock, Dividends, Per Share, Declared Dividends paid per common share Common Stock, Dividends, Per Share, Cash Paid Dividends declared per preferred share Preferred Stock, Dividends Per Share, Declared Dividends paid per preferred share Preferred Stock, Dividends, Per Share, Cash Paid SHAREHOLDERS’ EQUITY Stockholders' Equity Note Disclosure [Text Block] Statement of Stockholders' Equity [Abstract] Statement, Equity Components [Axis] Additional Paid-in Capital Additional Paid-in Capital [Member] Accumulated Dividends in Excess of Net Income Accumulated Distributions in Excess of Net Income [Member] Accumulated Other Comprehensive Loss AOCI Attributable to Parent [Member] Noncontrolling Interests Noncontrolling Interest [Member] Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Beginning balance (in shares) Shares, Outstanding Beginning balance Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest January 1, 2017 adoption of new accounting standard - See Note 2 Cumulative Effect on Retained Earnings, Net of Tax Net income, excluding $2,774 attributable to redeemable noncontrolling interests Profit Loss Excluding Redeemable Noncontrolling Interests Net income (loss) excluding portion attributable to redeemable noncontrolling interests. Other comprehensive income - change in fair value of interest rate swaps Other Comprehensive Income (Loss), Net of Tax Dividends declared to common shareholders Dividends, Common Stock, Cash Dividends declared to preferred shareholders Dividends, Preferred Stock, Cash Distributions declared to noncontrolling interests Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders Shares issued (in shares) Shares issued Stock Issued During Period, Value, New Issues Exercise of stock options (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period Exercise of stock options Stock Issued During Period, Value, Stock Options Exercised Shares issued under dividend reinvestment plan (in shares) Stock Issued During Period, Shares, Dividend Reinvestment Plan Shares issued under dividend reinvestment plan Stock Issued During Period, Value, Dividend Reinvestment Plan Share-based compensation expense, net of forfeitures (in shares) Share Based Compensation Expense Net Shares Number of shares issued during the period as a result of our long term incentive, bonus or other share based compensation plans, net of restricted share award forfeitures. Share-based compensation expense, net of forfeitures Share Based Compensation Expense Net Value This element represents the amount of recognized equity-based compensation related to other long-term incentive and bonus plans during the period, that is, the amount recognized as expense in the income statement (or as asset if compensation is capitalized). Shares withheld for employee taxes (in shares) Shares Paid for Tax Withholding for Share Based Compensation Shares withheld for employee taxes Adjustments Related to Tax Withholding for Share-based Compensation Conversion and redemption of OP units (in shares) Conversion and Redemption of Operating Partnership Units in Shares Number of shares issued during the period as a result of the conversion and redemption of operating partnership units into shares Conversion and redemption of OP units Conversion And Redemption Of Operating Partnership Units Decrease in noncontrolling interest as a result of redeeming, purchasing and/or converting to common stock the interests of Operating Partnership Units. Contributions from noncontrolling interests Contributions from noncontrolling interests Contributions from noncontrolling interests Purchase of noncontrolling interest Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests Ending balance (in shares) Ending balance New Accounting Pronouncements or Change in Accounting Principle [Table] New Accounting Pronouncements or Change in Accounting Principle [Table] Range [Axis] Range [Axis] Range [Domain] Range [Domain] Minimum Minimum [Member] Maximum Maximum [Member] New Accounting Pronouncements or Change in Accounting Principle [Line Items] New Accounting Pronouncements or Change in Accounting Principle [Line Items] Cumulative impact to additional paid in capital and retained earnings Payments related to shares withheld for employee taxes Acquisition related costs in the past several years Business Combination, Acquisition Related Costs Schedule of earnings per share Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Summary of dividends declared and paid per share Dividends Declared [Table Text Block] Fair Value, by Balance Sheet Grouping [Table] Fair Value, by Balance Sheet Grouping [Table] Term loan TermLoan [Member] TermLoan [Member] Accounts payable and accrued expenses Accounts Payable and Accrued Liabilities [Member] Accumulated other comprehensive loss Fair Value, Balance Sheet Grouping, Financial Statement Captions Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Number of interest rate swap agreements Number of Interest Rate Derivatives Held Notional amount of interest rate swap agreements Derivative Liability, Notional Amount Term loan Other Notes Payable Interest rate of variable portion of term loan Derivative, Fixed Interest Rate Interest rate cash flow hedge to be reclassified within next 12 months, net Interest Rate Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months, Net Other comprehensive income - change in value of interest rate swaps Interest expense reclassified from other comprehensive loss Interest Rate Cash Flow Hedge Gain (Loss) Reclassified to Earnings, Net Mortgages payable and notes payable Mortgages Payable And Notes Payable [Member] Mortgages Payable And Notes Payable [Member] Senior notes and debentures Senior Notes And Debentures [Member] Senior Notes And Debentures [Member] Measurement Basis [Axis] Measurement Basis [Axis] Fair Value Measurement [Domain] Fair Value Measurement [Domain] Portion at Fair Value Measurement [Member] Portion at Fair Value Measurement [Member] Carrying Value Reported Value Measurement [Member] Fair Value Estimate of Fair Value Measurement [Member] Fair value of long-term debt Long-term Debt, Fair Value Document And Entity Information [Abstract] Document and Entity Information Abstract Entity Registrant Name Entity Registrant Name Entity Central Index Key Entity Central Index Key Current Fiscal Year End Date Current Fiscal Year End Date Entity Filer Category Entity Filer Category Document Type Document Type Document Period End Date Document Period End Date Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Amendment Flag Amendment Flag Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding EARNINGS PER SHARE Earnings Per Share [Text Block] Los Angeles County Shopping Center Acquisition Square Footage of Properties Acquired Schedule of Real Estate Properties [Table Text Block] Pro Forma Information Business Acquisition, Pro Forma Information [Table Text Block] ASSETS Assets [Abstract] Operating (including $1,666,691 and $1,226,918 of consolidated variable interest entities, respectively) Rental Properties Construction-in-progress Construction in Progress, Gross Asset held for sale Real Estate Held-for-sale Real estate, at cost, total Real Estate Investment Property, at Cost Less accumulated depreciation and amortization (including $236,391 and $209,239 of consolidated variable interest entities, respectively) Real Estate Investment Property, Accumulated Depreciation Net real estate Real Estate Investment Property, Net Cash and cash equivalents Accounts and notes receivable, net Accounts and Notes Receivable, Net Mortgage notes receivable, net Mortgage Loans on Real Estate, Commercial and Consumer, Net Investment in real estate partnerships Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures Prepaid expenses and other assets Prepaid Expense and Other Assets TOTAL ASSETS Assets Liabilities Liabilities [Abstract] Mortgages payable (including $461,873 and $439,120 of consolidated variable interest entities, respectively) Secured Debt Capital lease obligations Capital Lease Obligations Notes payable Notes Payable Senior notes and debentures Senior Notes Accounts payable and accrued expenses Accounts Payable and Accrued Liabilities Dividends payable Dividends Payable Security deposits payable Security Deposit Liability Other liabilities and deferred credits Deferred Credits and Other Liabilities Total liabilities Liabilities Commitments and contingencies (Note 6) Commitments and Contingencies Redeemable noncontrolling interests Redeemable Noncontrolling Interest, Equity, Carrying Amount Shareholders’ equity Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract] Preferred shares, authorized 15,000,000 shares, $.01 par Preferred Stock, Value, Issued Common shares of beneficial interest, $.01 par, 100,000,000 shares authorized, 72,542,909 and 71,995,897 shares issued and outstanding, respectively Common Stock, Value, Issued Additional paid-in capital Additional Paid in Capital, Common Stock Accumulated dividends in excess of net income Accumulated Distributions in Excess of Net Income Accumulated other comprehensive loss Accumulated Other Comprehensive Income (Loss), Net of Tax Total shareholders’ equity of the Trust Stockholders' Equity Attributable to Parent Noncontrolling interests Stockholders' Equity Attributable to Noncontrolling Interest Total shareholders’ equity TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY Liabilities and Equity Schedule of Long-term Debt Instruments [Table] Schedule of Long-term Debt Instruments [Table] Senior unsecured notes Senior Notes [Member] Plaza El Segundo Plaza El Segundo [Member] Plaza El Segundo [Member] 3.25% Senior notes 3.25% Senior notes [Member] 3.25% Senior notes [Member] 4.50% Senior notes 4.50% Senior notes [Member] 4.50% Senior notes The Grove at Shrewsbury The Grove at Shrewsbury [Member] The Grove at Shrewsbury [Member] Debt Instrument [Line Items] Debt Instrument [Line Items] Principal amount Long-term Debt, Gross Repayment of mortgage loan at par Repayments of Long-term Debt Stated interest rate Debt Instrument, Interest Rate, Stated Percentage Note offering percent of principal amount Note Offering Percent Note offering percent of principal amount Debt yield to maturity percent Debt Instrument, Interest Rate, Effective Percentage Net proceeds from issuance of senior notes Debt Instrument, Fair Value Disclosure Debt Instrument, Fair Value Disclosure Refinance of mortgage loan Maximum borrowing capacity under revolving credit facility Line of Credit Facility, Maximum Borrowing Capacity Maximum amount outstanding under revolving credit facility Line of Credit Facility, Maximum Amount Outstanding During Period Weighted average interest rate, before amortization of debt fees LineofCreditFacilityWeightedAverageInterestRateBeforeAmortizationOfDebt Fees Line of credit facility weighted average interest rate, before amortization of debt fees. Weighted average borrowings outstanding Line of Credit Facility, Average Outstanding Amount Outstanding balance of revolving credit facility Long-term Line of Credit Assembly Row and Pike & Rose Assembly Row and Pike & Rose [Member] Assembly Row and Pike & Rose [Member] Number of condominium units under construction Number of Units in Real Estate Property FAIR VALUE OF FINANCIAL INSTRUMENTS Fair Value Disclosures [Text Block] Net income attributable to redeemable noncontrolling interests Net Income (Loss) Attributable to Redeemable Noncontrolling Interest