Accounting Policies [Abstract] Total interest costs incurred Interest Costs Incurred Interest capitalized Interest Costs Capitalized Adjustment 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 loan refinanced Refinance of mortgage loan Refinance of mortgage loan 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 Real Estate [Abstract] 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. Disclosure of Compensation Related Costs, Share-based Payments [Abstract] SHARE-BASED COMPENSATION PLANS Disclosure of Compensation Related Costs, Share-based Payments [Text Block] Earnings Per Share [Abstract] EARNINGS PER SHARE Earnings Per Share [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] Dividends [Abstract] Dividends Payable [Table] Dividends Payable [Table] Class of Stock [Axis] Class of Stock [Axis] Class of Stock Class of Stock [Domain] 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] 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] Dividends Dividends Payable [Line Items] Dividends declared per common share Common Stock, Dividends, Per Share, Declared Dividends paid per common share Common Stock, Dividends, Per Share, Cash Paid Preferred shares, percentage Preferred Stock, Dividend Rate, Percentage Dividends declared per preferred shares Preferred Stock, Dividends Per Share, Declared Dividends paid per preferred share Preferred Stock, Dividends, Per Share, Cash Paid 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 Fair Value Disclosures [Abstract] Fair Value, by Balance Sheet Grouping [Table] Fair Value, by Balance Sheet Grouping [Table] Derivative Instrument Derivative Instrument [Axis] Derivative, Name [Domain] Derivative Contract [Domain] Interest Rate Swap Interest Rate Swap [Member] Measurement Frequency [Axis] Fair Value, Measurement Frequency [Domain] Fair Value, Measurements, Recurring Fair Value, Measurements, Recurring [Member] Debt Instrument [Axis] Debt Instrument [Axis] Debt Instrument Debt Instrument, Name [Domain] Term loan TermLoan [Member] TermLoan [Member] Balance Sheet Location [Axis] Balance Sheet Location [Axis] Balance Sheet Location [Domain] Balance Sheet Location [Domain] Prepaid expenses and other assets prepaid expenses and other assets [Member] prepaid expenses and other assets Fair Value, Hierarchy [Axis] Fair Value Hierarchy [Domain] Level 2 Fair Value, Inputs, Level 2 [Member] Equity Components [Axis] Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] Accumulated other comprehensive income AOCI Attributable to Parent [Member] 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 Fair value of interest rate swaps Derivative Liability (Decrease) increase in our derivative asset Other Comprehensive Income (Loss), Net of Tax Interest expense reclassified from other comprehensive income Interest Rate Cash Flow Hedge Gain (Loss) Reclassified to Earnings, Net 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] Recently Adopted Accounting Pronouncements New Accounting Pronouncements and Changes in Accounting Principles [Text Block] Statement of Stockholders' Equity [Abstract] Statement [Table] Statement [Table] Preferred Shares Preferred Stock [Member] Common Shares Common Stock [Member] 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 Income Noncontrolling Interests Noncontrolling Interest [Member] Statement [Line Items] Statement [Line Items] 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, 2018 adoption of new accounting standard - See Note 2 Cumulative Effect on Retained Earnings, Net of Tax Net income, excluding $1,998 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 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) Stock Issued During Period, Shares, New Issues 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 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 Ending balance (in shares) Ending balance Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract] Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Restricted cash Restricted Cash and Cash Equivalents Total cash, cash equivalents, and restricted cash Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents Commitments and Contingencies Disclosure [Abstract] COMMITMENTS AND CONTINGENCIES Commitments and Contingencies Disclosure [Text Block] 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] Stockholders' Equity Note [Abstract] Schedule of Stock by Class [Table] Schedule of Stock by Class [Table] 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] Subsequent Event Type [Axis] Subsequent Event Type [Axis] Subsequent Event Type [Domain] Subsequent Event Type [Domain] Subsequent Event Subsequent Event [Member] Class of Stock [Line Items] Class of Stock [Line Items] Aggregate offering price of common share Aggregate Offering Price Of Common Share Maximum aggregate offering price of common shares. Shares sold Common shares sold prior to the period end, but subsequently settled Common shares sold and settled Common shares sold before the end of current period, but subsequently settled. 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 Commissions related to sales of common shares Payments of Stock Issuance Costs Remaining capacity to issue Remaining Capacity To Issue Remaining $ Capacity Of Shares To Issue Supplemental disclosures related to the Consolidated Statements Of Cash Flows Schedule of Cash Flow, Supplemental Disclosures [Table Text Block] Reconciliation of cash, cash equivalents, and restricted cash Schedule of Cash and Cash Equivalents [Table Text Block] Fair Value Measurements, Recurring and Nonrecurring [Table] Fair Value Measurements, Recurring and Nonrecurring [Table] Measurement Frequency [Axis] Fair Value, Measurement Frequency [Domain] Fair Value, Hierarchy [Axis] Fair Value Hierarchy [Domain] Level 1 Fair Value, Inputs, Level 1 [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] Schedule of Significant Acquisitions [Table] Schedule of Business Acquisitions, by Acquisition [Table] Name of Property [Axis] Name of Property [Axis] Name of Property [Domain] Name of Property [Domain] Jordan Downs Plaza Jordan Downs Plaza [Member] Jordan Downs Plaza [Member] Assembly Row and Pike & Rose Assembly Row and Pike & Rose [Member] Assembly Row and Pike & Rose [Member] Property, Plant and Equipment, Type [Axis] Property, Plant and Equipment, Type [Axis] Property, Plant and Equipment, Type [Domain] Property, Plant and Equipment, Type [Domain] Condominiums Condominiums [Member] Condominiums [Member] Significant Acquisition and Dispositions Business Acquisition [Line Items] Square footage of real estate property Area of Real Estate Property Construction pre-funding investment Construction pre-funding investment Investment to pre-fund construction due to funding requirement. Controlling interest percentage Variable Interest Entity, Qualitative or Quantitative Information, Ownership Percentage Land parcel acre on which the shopping center will be constructed Area of Land Contributions from a third party bank Contribution from third party bank Contribution from third party bank Strike price of put option Strike price of put option Strike price of put option Direct and incremental costs of structuring the NMTC transaction Direct and incremental costs of structuring the NMTC transaction Direct and incremental costs of structuring the NMTC transaction Cash in escrow to be used for development Restricted Cash Number of condominium units sold Number of condominium units sold Number of condominium units sold Proceeds from sale Sales of Real Estate Gain on sale Gain (Loss) on Sale of Properties Taxes related to the sale of condominiums Gain (Loss) on Sale of Properties, Applicable Income Taxes Assets held for sale Real Estate Held-for-sale 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. Schedule of earnings per share Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] FAIR VALUE OF FINANCIAL INSTRUMENTS Fair Value Disclosures [Text Block] BUSINESS AND ORGANIZATION Nature of Operations [Text Block] 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, net Gain (Loss) on Sale of Properties, Net of Applicable Income Taxes Loss 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] Proceeds from new market tax credit transaction, net of deferred costs Proceeds from new market tax credit transaction, net of deferred costs Proceeds from new market tax credit transaction, net of deferred costs (Increase) decrease in accounts receivable, net Increase (Decrease) in Accounts and Other Receivables Decrease in prepaid expenses and other assets Increase (Decrease) in Prepaid Expense and Other Assets (Decrease) increase in accounts payable and accrued expenses Increase (Decrease) in Accounts Payable and Accrued Liabilities Increase 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 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 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 (used in) provided by financing activities Net Cash Provided by (Used in) Financing Activities Increase (decrease) in cash, cash equivalents and restricted cash Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect Cash, cash equivalents, and restricted cash at beginning of year Cash, cash equivalents, and restricted cash at end of period SHAREHOLDERS’ EQUITY Stockholders' Equity Note Disclosure [Text Block] Statement of Financial Position [Abstract] 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. Construction-in-progress, consolidated variable interest entities Constructioninprogresofconsolidatedvariableieestentity Construction-in-progress oc consolidated variable interest entity 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. 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. Preferred shares, authorized Preferred Stock, Shares Authorized Preferred shares, par value Preferred Stock, Par or Stated Value Per Share Preferred shares, liquidation preference Preferred Stock, Liquidation Preference Per Share 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 5.0% Series C Cumulative Redeemable Preferred Shares, (stated at liquidation preference $25,000 per share), 6,000 shares issued and outstanding 5.417% Series 1 Cumulative Convertible Preferred Shares, (stated at liquidation preference $25 per share), 399,896 shares issued and outstanding ASSETS Assets [Abstract] Operating (including $1,660,403 and $1,639,486 of consolidated variable interest entities, respectively) Rental Properties Construction-in-progress (including $47,251 and $43,393 of consolidated variable interest entities, respectively) Construction in Progress, Gross Real estate, at cost, total Real Estate Investment Property, at Cost Less accumulated depreciation and amortization (including $268,723 and $247,410 of consolidated variable interest entities, respectively) Real Estate Investment Property, Accumulated Depreciation Net real estate Real Estate Investment Property, Net 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, net (including $447,246 and $460,372 of consolidated variable interest entities, respectively) Secured Debt Capital lease obligations Capital Lease Obligations Notes payable, net Notes Payable Senior notes and debentures, net 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, 73,434,943 and 73,090,877 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 income 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 Debt Instruments [Abstract] Schedule of Long-term Debt Instruments [Table] Schedule of Long-term Debt Instruments [Table] Long-term Debt, Type [Axis] Long-term Debt, Type [Axis] Long-term Debt, Type Long-term Debt, Type [Domain] Mortgage loan Mortgages [Member] The Grove at Shrewsbury (West) The Grove at Shrewsbury (West) [Member] The Grove at Shrewsbury (West) Debt Instrument [Line Items] Debt Instrument [Line Items] Principal amount of mortgage loan repayment Repayments of Secured Debt 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 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. Document And Entity Information [Abstract] Document and Entity Information Abstract 6/30/2018 Document Period End Date 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 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 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 New Accounting Pronouncements or Change in Accounting Principle [Table] New Accounting Pronouncements or Change in Accounting Principle [Table] Customer [Axis] Customer [Axis] Customer [Domain] Customer [Domain] Condominium sales Condominium sales [Member] Condominium sales Additional cumulative effect Additional cumulative effect [Member] Additional cumulative effect [Member] Adjustments for New Accounting Pronouncements [Axis] Adjustments for New Accounting Pronouncements [Axis] Type of Adoption [Domain] Type of Adoption [Domain] ASU 2016-18 Accounting Standards Update 2016-18 [Member] Scenario [Axis] Scenario [Axis] Scenario, Unspecified [Domain] Scenario, Unspecified [Domain] Before adoption of standard Scenario, Previously Reported [Member] After adoption of standard Restatement Adjustment [Member] New Accounting Pronouncements or Change in Accounting Principle [Line Items] New Accounting Pronouncements or Change in Accounting Principle [Line Items] Cumulative impact to accumulated dividends in excess of net income, net of tax Cumulative impact to accumulated dividends in excess of net income, tax Cumulative Effect on Retained Earnings, Tax Net cash provided by operating activities Net cash used in investing activities Properties subject to ground leases Number of Properties Subject to Ground Leases Capital leases Capital Leased Assets, Number of Units Capitalized internal leasing and external legal leasing costs Capitalized internal leasing and external legal leasing costs Internal leasing and external leasing costs that have been capitalized during the period 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] 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, net Gain on sale of real estate, net Gain (loss) on 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 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 Net income attributable to redeemable noncontrolling interests Net Income (Loss) Attributable to Redeemable Noncontrolling Interest 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 Below Market Lease [Member] Below Market Lease [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 Summary of dividends declared and paid per share Dividends Declared [Table Text Block] 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 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] DEBT Debt Disclosure [Text Block] 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 from real estate partnerships INCOME FROM CONTINUING OPERATIONS Gain on sale of real estate, 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