Construction-in-progress, consolidated variable interest entities Constructioninprogresofconsolidatedvariableieestentity Construction-in-progress oc consolidated variable interest entity Acquired lease assets, Accumulated Amortization Finite-Lived Intangible Assets, Accumulated Amortization Laurel Laurel [Member] Laurel [Member] Entity Listings, Exchange [Axis] Entity Listings, Exchange [Axis] Award Timing Predetermined Award Timing Predetermined [Flag] Entity File Number Entity File Number Additional Paid-in Capital Additional Paid-in Capital [Member] Line of credit facility, annual facility fee Line of credit facility, annual facility fee Line of credit facility, annual facility fee Tabular List, Table Tabular List [Table Text Block] 3.25% exchangeable notes 3.25% Exchangeable senior notes [Member] 3.25% Exchangeable senior notes Fourth Quarter Quarter [Member] Quarter Common units issued under dividend reinvestment plan Common units issued under dividend reinvestment plan Common units issued under dividend reinvestment plan Mortgages payable, consolidated variable interest entities Mortgage Payable From Consolidated Variable Interest Entities Mortgage Payable From Consolidated Variable Interest Entities Mortgages payable balances from variable interest entities, or VIEs, for the periods presented. Principal Amount of Loans Subject to delinquent Principal or Interest SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate, Principal Amount of Delinquent Loans Grants of common shares and options Share-Based Payment Arrangement [Member] Linden Square Linden Square [Member] Linden Square [Member] Measurement Basis [Axis] Measurement Basis [Axis] Adjustment to Compensation: Adjustment to Compensation [Axis] Named Executive Officers, Footnote Named Executive Officers, Footnote [Text Block] Darien Commons Darien [Member] Darien [Member] Contractual Obligation [Axis] Contractual Obligation [Axis] Contractual Obligation [Axis] Operating lease, term Operating Lease, Term Operating Lease, Term Willow Lawn Willow Lawn [Member] Willow Lawn [Member] Gross amount at which carried at close of period, Buildings and Improvements SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Building and Improvements, Amount Stock, Class of Stock [Table] Stock, Class of Stock [Table] Number of mortgage receivables SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate, Number of Loans 3.25% notes 3.25% Senior notes [Member] 3.25% Senior notes [Member] Reconcilition of cash, cash equivalents, and restricted cash Schedule of Cash and Cash Equivalents [Table Text Block] Square footage of real estate property Area of Real Estate Property Weighted average unvested shares outstanding Incremental Common Shares Attributable to Participating Nonvested Shares with Non-forfeitable Dividend Rights Mortgage loans refinanced Refinance of mortgage loan Refinance of mortgage loan Adjustment to Compensation, Amount Adjustment to Compensation Amount Forward Sales Contracts Forward Sales Contracts [Member] Forward Sales Contracts Net unamortized debt issuance costs and premium Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net Principles of Consolidation Consolidation, Policy [Policy Text Block] Share-based compensation expense Share-Based Payment Arrangement, Noncash Expense Sales price of real estate Sales price of real estate The gross sales price of real estate sold. Options Share-Based Payment Arrangement, Option [Member] Weighted average interest rate, before amortization of debt fees LineofCreditFacilityWeightedAverageInterestRateBeforeAmortizationOfDebt Fees Line of credit facility weighted average interest rate, before amortization of debt fees. Property, Plant and Equipment [Table] Property, Plant and Equipment [Table] Mortgage receivable, net of valuation allowances Financing Receivable, after Allowance for Credit Loss Cash and Cash Equivalents Cash and Cash Equivalents, Policy [Policy Text Block] Long Lived Assets and Impairment Property, Plant and Equipment, Impairment [Policy Text Block] $750M Term Loan $750M Term Loan [Member] $750M Term Loan Dividends declared to common shareholders Dividends, Common Stock, Cash Impairment charge Impairment charge Impairment Charge Asset Impairment Charges Total shareholders’ equity of the Trust Equity, Attributable to Parent Measurement Frequency [Axis] Measurement Frequency [Axis] Insider Trading Policies and Procedures [Line Items] Repayment of mortgages, finance leases, and notes payable Repayment of mortgages, finance leases, and notes payable Repayment of mortgages, finance leases, and notes payable Common shares of beneficial interest, shares authorized Common Stock, Shares Authorized Crow Canyon Commons Crow Canyon [Member] Crow Canyon [Member] Common units, 86,266,009 and 85,666,220 units issued and outstanding, respectively Common Units Capital Accounts Common Units Capital Accounts Value Common shares issued, net (in shares) Shares issued Stock Issued During Period, Shares, New Issues Fair Value, Measurements, Recurring Fair Value, Recurring [Member] Finite-Lived Intangible Liabilities By Major Class [Axis] Finite-Lived Intangible Liabilities By Major Class [Axis] Finite-Lived Intangible Liabilities By Major Class [Axis] Below Market Lease Below Market Lease [Member] Below Market Lease [Member] Cover [Abstract] Cover [Abstract] Portion at Fair Value Measurement Portion at Fair Value Measurement [Member] Common unit, outstanding Common Unit, Outstanding Maximum Maximum [Member] Exercisable at the end of the year, Weighted-Average Exercise Price (in dollars per share) Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Exercisable, Weighted Average Exercise Price The Shoppes At Nottingham Square Shoppes At Nottingham Square [Member] Shoppes At Nottingham Square [Member] Net income attributable to noncontrolling interests Less: Income from operations attributable to noncontrolling interests Net Income (Loss) Attributable to Noncontrolling Interest Troy Hills Troy [Member] Troy [Member] Total future amortization expense from acquired lease assets Finite-Lived Intangible Assets, Net Restricted Stock Restricted Stock [Member] Non-PEO NEO Average Total Compensation Amount Non-PEO NEO Average Total Compensation Amount Real Estate and Accumulated Depreciation, by Property [Table] SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, by Property [Table] Debt Instrument [Line Items] Debt Instrument [Line Items] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Share-Based Compensation Arrangements by Share-Based Payment Award [Table] Cost Capitalized Subsequent to Acquisition SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Cost Capitalized Subsequent to Acquisition, Cost Summary of restricted share activity Share-Based Payment Arrangement, Restricted Stock and Restricted Stock Unit, Activity [Table Text Block] CocoWalk CocoWalk [Member] CocoWalk Adjustment to Non-PEO NEO Compensation Footnote Adjustment to Non-PEO NEO Compensation Footnote [Text Block] New market tax credit income, net of income attributable to noncontrolling interest New market tax credit income, net of income attributable to noncontrolling interest New market tax credit income, net of income attributable to noncontrolling interest Forgone Recovery due to Disqualification of Tax Benefits, Amount Forgone Recovery due to Disqualification of Tax Benefits, Amount Other Assets Other Assets [Member] Tower Shops Tower Shops January 19 2011 [Member] Tower Shops 1/19/11 [Member] Non-Rule 10b5-1 Arrangement Terminated Non-Rule 10b5-1 Arrangement Terminated [Flag] Entity Shell Company Entity Shell Company Summary of carrying amount and fair value of financial instruments Schedule of Carrying Values and Estimated Fair Values of Debt Instruments [Table Text Block] Schedule of Long-term Debt Instruments [Table] Schedule of Long-Term Debt Instruments [Table] Proceeds from issuance of debt Proceeds from Issuance of Debt Reconciliation of Real Estate Accumulated Depreciation [Roll Forward] SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation [Roll Forward] Andorra Andorra Shopping Center [Member] Andorra Shopping Center [Member] Statement of Stockholders' Equity [Abstract] Statement of Stockholders' Equity [Abstract] Capitalized share-based compensation Share-Based Payment Arrangement, Amount Capitalized Other Postretirement Benefits, Individual Contracts, Type of Deferred Compensation [Axis] Other Postretirement Benefits, Individual Contracts, Type of Deferred Compensation [Axis] Schedule of supplemental disclosures related to the Consolidated Statements Of Cash Flows Schedule of Cash Flow, Supplemental Disclosures [Table Text Block] Comprehensive income attributable to noncontrolling interests Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest Award Timing MNPI Considered Award Timing MNPI Considered [Flag] Option Indexed to Issuer's Equity, Type [Domain] Option Indexed to Issuer's Equity, Type [Domain] Debt conversion Debt Conversion, Name [Domain] Summary of share-based compensation expense Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Table Text Block] Management fees and costs Management Fee Expense Finance Lease, interest on lease liabilities Finance Lease, Interest Expense Document Fiscal Period Focus Document Fiscal Period Focus Return of capital, common shares Common shares, return of capital Common shares, return of capital Payments from reserves Standard and Extended Product Warranty Accrual, Decrease for Payments Real estate taxes Real Estate Tax Expense Derivatives, Fair Value [Line Items] Derivatives, Fair Value [Line Items] Award Timing Method Award Timing Method [Text Block] Award Type [Axis] Award Type [Axis] Minimum percentage of taxable income distributed to shareholders Minimum Percentage Of Taxable Income Distributed To Shareholders Minimum percentage of taxable income distributed to shareholders. Share Based Compensation Share-Based Payment Arrangement [Policy Text Block] Accumulated Dividends in Excess of Net Income Accumulated Distributions in Excess of Net Income [Member] At The Market Equity Program At The Market Equity Program [Member] At The Market Equity Program [Member] Trading Symbol Trading Symbol 2029 Lessee, Operating Lease, Liability, to be Paid, Year Four Purchase price of real estate acquisition Purchase price of fee interest in real estate Purchase price of fee interest in real estate Entity Address, City Entity Address, City or Town Weighted-average discount rate - finance leases Finance Lease, Weighted Average Discount Rate, Percent Put Option Put Option [Member] Preferred Units by Name [Axis] Preferred Units by Name [Axis] ACQUIRED IN-PLACE LEASES Intangible Assets Disclosure [Text Block] Freedom Plaza Jordan Downs Plaza [Member] Jordan Downs Plaza [Member] Non-PEO NEO Average Compensation Actually Paid Amount Non-PEO NEO Average Compensation Actually Paid Amount Restricted stock units Restricted Stock Units (RSUs) [Member] Per $1,000 principal amount Per $1,000 principal amount [Member] Per $1,000 principal amount Bell Gardens Bell Gardens [Member] Bell Gardens [Member] Depositary Shares Depository Shares [Member] Depository Shares [Member] Compensation Actually Paid vs. Other Measure Compensation Actually Paid vs. Other Measure [Text Block] Georgetowne Shopping Center Georgetowne Shopping Center [Member] Georgetowne Shopping Center Entity Emerging Growth Company Entity Emerging Growth Company 2028 Long-Term Debt, Maturity, Year Three Weighted-average remaining lease term - finance leases Finance Lease, Weighted Average Remaining Lease Term Outstanding at the beginning of year (in shares) Outstanding at the end of year (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Number Change in Fair Value as of Vesting Date of Prior Year Equity Awards Vested in Covered Year Change in Fair Value as of Vesting Date of Prior Year Equity Awards Vested in Covered Year [Member] Minimum redemption exchange price Minimum redemption exchange price Minimum redemption exchange price Net unamortized debt issuance costs Debt Issuance Costs, Net Other notes payable Other Notes Payable Restricted cash Restricted Cash and Cash Equivalent Acquired lease costs Leases, Acquired-in-Place [Member] Less amount representing interest Finance Lease, Liability, Undiscounted Excess Amount Net income available for common shareholders, basic Net income available for common shareholders, basic Net income available for common shareholders, basic Debt Conversion Description [Axis] Debt Conversion Description [Axis] Common shares of beneficial interest, shares outstanding Common Stock, Shares, Outstanding Commissions Commissions [Member] Commissions [Member] Issuance and extension of mortgages and notes payable, net of costs Issuance of mortgages and notes payable, net of costs Issuance of mortgages and notes payable, net of costs Issuance of senior notes, net of costs Proceeds from Issuance of Senior Long-Term Debt Initial cost to company, Buildings and Improvements SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Building and Improvements Dividends or Other Earnings Paid on Equity Awards not Otherwise Reflected in Total Compensation for Covered Year Dividends or Other Earnings Paid on Equity Awards not Otherwise Reflected in Total Compensation for Covered Year [Member] Amortization for acquired leases during the next five years and thereafter Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block] Accounts payable and accrued expenses Accounts Payable and Accrued Liabilities Option By Type [Domain] Option By Type [Domain] Option By Type [Domain] Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward] Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward] Effective interest rate Debt Instrument, Interest Rate, Effective Percentage Savings and Retirement Plans [Abstract] Savings and Retirement Plans [Abstract] Savings and Retirement Plans [Abstract] Entity Address, Postal Zip Code Entity Address, Postal Zip Code Restatement Determination Date Restatement Determination Date Unvested restricted stock shares Unvested performance shares Unvested performance shares Unvested performance shares Life on  which depreciation in latest income statements is computed SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Life Used for Depreciation Basis spread Debt Instrument, Basis Spread on Variable Rate Conversion and redemption of downREIT OP units Partners' Capital Account, Exchanges and Conversions Mortgages payable and notes payable Mortgages Payable And Notes Payable [Member] Mortgages Payable And Notes Payable [Member] Montrose Crossing Montrose Crossing [Member] Montrose Crossing [Member] Statement of Financial Position Location, Activity, Capitalization [Axis] Statement of Financial Position Location, Activity, Capitalization [Axis] Preferred shares, issued Preferred Stock, Shares Issued Senior notes and debentures, net Unsecured Debt Pension Adjustments Service Cost Pension Adjustments Service Cost [Member] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Amortization of above market leases, lessee Amortization Of Intangible Liability Amortization Of Intangible Liability 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. Below Market Leases, Lessee BelowMarketLeasesLessee [Member] Below Market Leases, Lessee Notes Payable Notes Payable, Other Payables [Member] OTHER INCOME/(EXPENSE) Other Income and Expenses [Abstract] Compensation Actually Paid vs. Company Selected Measure Compensation Actually Paid vs. Company Selected Measure [Text Block] Building and major improvements Building and Building Improvements [Member] All Trading Arrangements All Trading Arrangements [Member] Equity Awards Adjustments, Footnote Equity Awards Adjustments, Footnote [Text Block] Total Shareholder Return Vs Peer Group Total Shareholder Return Vs Peer Group [Text Block] Note offering percent Debt Instrument, Redemption Price, Percentage Dividends on preferred shares Less: Preferred share dividends Preferred Stock Dividends, Income Statement Impact SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation Disclosure [Abstract] SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation Disclosure [Abstract] Colorado Blvd Colorado Blvd [Member] Colorado Blvd [Member] Unvested at the beginning of year (in shares) Unvested at the end of year (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Number Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Disclosure [Abstract] 2026 Below Market Lease, Amortization Income, Year One Graham Park Plaza Graham Park [Member] Graham Park 3.50% notes 3.5% Senior Note [Member] 3.5% Senior Note Net cash provided by operating activities Cash Provided by (Used in) Operating Activity, Including Discontinued Operation Estimated useful lives Property, Plant and Equipment, Useful Life Preferred shares, par value Preferred shares, par value Preferred Stock, Par or Stated Value Per Share Subsequent Event Subsequent Event [Member] Summary of weighted average assumptions used to value options granted Schedule of Share-Based Payment Award, Stock Options, Valuation Assumptions [Table Text Block] Equity Valuation Assumption Difference, Footnote Equity Valuation Assumption Difference, Footnote [Text Block] PEO Total Compensation Amount PEO Total Compensation Amount Long-term Debt, Type [Axis] Long-Term Debt, Type [Axis] 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. 2029 Finance Lease, Liability, to be Paid, Year Four Del Mar Village Del Mar Village [Member] Del Mar Village [Member] Equity Components Equity Components [Axis] EARNINGS PER COMMON UNIT, DILUTED EARNINGS PER COMMON UNIT, DILUTED [Abstract] EARNINGS PER COMMON UNIT, DILUTED Property, Plant and Equipment [Line Items] Property, Plant and Equipment [Line Items] Exchangeable Senior Notes Convertible Debt [Member] A residential building at our Santana Row property and Courthouse Center property A residential building at Santana Row and Courthouse Center [Member] A residential building at Santana Row and Courthouse Center Aggregate tax basis for Federal tax purposes SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate, Federal Income Tax Basis Non-Rule 10b5-1 Arrangement Adopted Non-Rule 10b5-1 Arrangement Adopted [Flag] Weighted average number of common units Weighted average common units outstanding—basic Weighted Average Limited Partnership and General Partnership Units Outstanding, Basic Number of segments Number of Reportable Segments Schedule of Operating Leased Assets [Table] Schedule of Operating Leased Assets [Table] Mount Vernon/South Valley/7770 Richmond Hwy. Mount Vernon [Member] Mount Vernon [Member] Commercial Commercial Real Estate [Member] Lancaster Lancaster [Member] Lancaster [Member] Entity Address, State or Province Entity Address, State or Province Financing cash flows for finance leases Finance Lease, Principal Payments Acquisitions SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Other Acquisition Debt Instrument, Unused Borrowing Capacity, Amount Debt Instrument, Unused Borrowing Capacity, Amount Operating Leased Assets [Line Items] Operating Leased Assets [Line Items] EARNINGS PER COMMON UNIT, BASIC EARNINGS PER COMMON UNIT, BASIC [Abstract] EARNINGS PER COMMON UNIT, BASIC Individual: Individual [Axis] Operating Leases, Future Minimum Payments Lessor, Operating Lease, Payment to be Received, Fiscal Year Maturity [Abstract] Document Annual Report Document Annual Report Distributions to and acquisition/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. Entities [Table] Entities [Table] 401(k) Maximum annual contribution per employee Defined Contribution Plan, Maximum Annual Contributions Per Employee, Amount Amortization of below market leases, lessor Amortization of Below Market Lease Contributions from noncontrolling interests Proceeds from Noncontrolling Interests Maximum exposure to loss in variable interest entity Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount Forgone Recovery, Explanation of Impracticability Forgone Recovery, Explanation of Impracticability [Text Block] Option By Type [Axis] Option By Type [Axis] Option By Type [Axis] Repayment of mortgage loan Repayments of Long-Term Debt Entity Interactive Data Current Entity Interactive Data Current Common units issued as a result of common stock issued by Parent Company, net of issuance costs Partners' Capital Account, Contributions 2028 Below Market Lease, Amortization Income, Year Three 2027 Below Market Lease, Amortization Income, Year Two Lawrence Park Lawrence Park [Member] Lawrence Park [Member] 3.25% notes Senior 3 Point 25 Percent Notes [Member] Senior 3 Point 25 Percent Notes Exercisable at the end of year, Aggregate Intrinsic Value Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Exercisable, Intrinsic Value Schedule of common shares awarded under various compensation plans Disclosure of Share-Based Compensation Arrangements by Share-Based Payment Award [Table Text Block] Property, Plant and Equipment, Type [Axis] Long-Lived Tangible Asset [Axis] Change in redemption value Temporary Equity, Other Changes Wildwood Wildwood [Member] Wildwood [Member] Ownership [Domain] Ownership [Domain] Initial cost to company, Land SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Land Stock Issuance Costs by Type [Domain] Stock Issuance Costs by Type [Domain] [Domain] for Stock Issuance Costs by Type [Axis] 2027 Finance Lease, Liability, to be Paid, Year Two Schedule of minimum future commercial property rentals from noncancelable operating leases Lessor, Operating Lease, Payment to be Received, Maturity [Table Text Block] Entity Central Index Key Entity Central Index Key PEO Name PEO Name Exchange price Debt Instrument, Convertible, Conversion Price Total future amortization expense from acquired below market leases Below Market Lease, Net Schedule of principal payments on mortgages payable, notes payable, senior notes and debentures Schedule of Maturities of Long-Term Debt [Table Text Block] Total revenue Revenues Prior Year End Fair Value of Equity Awards Granted in Any Prior Year that Fail to Meet Applicable Vesting Conditions During Covered Year Prior Year End Fair Value of Equity Awards Granted in Any Prior Year that Fail to Meet Applicable Vesting Conditions During Covered Year [Member] Fair Value, Balance Sheet Grouping, Financial Statement Captions Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Investment in partnerships Payments to Acquire Interest in Subsidiaries and Affiliates Outstanding Aggregate Erroneous Compensation Amount Outstanding Aggregate Erroneous Compensation Amount Preferred Units 5.417% Series 1 Cumulative Convertible Preferred Units Preferred Units [Member] Preferred Units Sylmar Towne Center Sylmar Towne Center [Member] Sylmar Town Center Minor improvements, furniture and equipment Minor Improvements, Furniture and Equipment [Member] Minor Improvements, Furniture and Equipment [Member] Exchangeable Senior Notes [Line Items] Exchangeable Senior Notes [Line Items] Exchangeable Senior Notes Increase in prepaid expenses and other assets Increase (Decrease) in Prepaid Expense and Other Assets SEC Schedule, 12-29, Real Estate Companies, Investment in Movement in Mortgage Loans on Real Estate [Roll Forward] SEC Schedule, 12-29, Real Estate Companies, Investment in Movement in Mortgage Loans on Real Estate [Roll Forward] Exercise Price Award Exercise Price Entity Filer Category Entity Filer Category Class of Stock Class of Stock [Domain] COMPONENTS OF RENTAL EXPENSE Operating Leases Revenue And Expense Text Block [Text Block] The principal components of rental income and/or rental expense recognized for the period. Subsequent Event Type [Axis] Subsequent Event Type [Axis] Plaza Del Mercado Plaza Del Mercado [Member] Plaza Del Mercado 2028 Finite-Lived Intangible Asset, Expected Amortization, Year Three Statement of Financial Position Location, Balance [Axis] Statement of Financial Position Location, Balance [Axis] Contractual Obligation [Domain] Contractual Obligation [Domain] Contractual Obligation [Domain] Acquired lease assets, Cost Finite-Lived Intangible Assets, Gross Vesting Date Fair Value of Equity Awards Granted and Vested in Covered Year Vesting Date Fair Value of Equity Awards Granted and Vested in Covered Year [Member] Net income available for common unit holders Net Income (Loss), Per Outstanding Limited Partnership and General Partnership Unit, Diluted, Net of Tax Net Income (Loss), Per Outstanding Limited Partnership and General Partnership Unit, Diluted, Net of Tax Number of states in which entity has properties Number of States in which Entity Operates Entity Address, Address Entity Address, Address Line One Accumulated Other Comprehensive Income (loss) Accumulated Other Comprehensive (loss) income AOCI Attributable to Parent [Member] Common Shares Of Beneficial Interest Common Shares Of Beneficial Interest [Member] Common Shares Of Beneficial Interest [Member] Shares withheld for employee taxes (in shares) Share-Based Payment Arrangement, Shares Withheld for Tax Withholding Obligation Redeemable noncontrolling interests Beginning balance Ending balance Redeemable Noncontrolling Interest, Equity, Carrying Amount Providence Place (formerly Pan Am) Pan Am Shopping Center [Member] Pan Am Shopping Center [Member] Ownership [Axis] Ownership [Axis] Other Liabilities Other Liabilities [Member] Village Pointe Village Pointe [Member] Village Pointe Name of Property Name of Property [Domain] Fair Value as of Grant Date Award Grant Date Fair Value East Bay Bridge East Bay Bridge [Member] EastBayBridge [Member] Number of leases Number Of Leases Number Of Leases Unvested restricted stock units Unvested performance units Unvested performance units Unvested performance units Preferred Units, Class [Domain] Preferred Units, Class [Domain] Estimated maximum liability upon exercise of the put option Estimated Liability Upon Exercise Of Option Estimated Liability Upon Exercise Of Option Payments of ordinary dividends, common stock Common Stock, Ordinary Dividends, Per Share, Cash Paid Common Stock, Ordinary Dividends, Per Share, Cash Paid Granted (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period Title and Position [Domain] Title and Position [Domain] Total unrecognized compensation cost related to unvested share-based compensation arrangements Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount Forfeited (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Forfeited in Period Valuation adjustments Valuation adjustments Mortgage loans on real estate valuation adjustments Fair value of long-term debt Long-Term Debt, Fair Value Changed Peer Group, Footnote Changed Peer Group, Footnote [Text Block] Brick Plaza Brick Plaza [Member] Brick Plaza [Member] 2027 Lessee, Operating Lease, Liability, to be Paid, Year Two Fair Values Derivatives, Balance Sheet Location, by Derivative Contract Type [Table] Fair Values Derivatives, Balance Sheet Location, by Derivative Contract Type [Table] Adjustment To PEO Compensation, Footnote Adjustment To PEO Compensation, Footnote [Text Block] Outstanding at the end of year, Weighted-Average Remaining Contractual Term (in years) Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term Title Trading Arrangement, Individual Title Peer Group Total Shareholder Return Amount Peer Group Total Shareholder Return Amount Prepaid expenses and other assets Prepaid Expense and Other Assets Non-PEO NEO Non-PEO NEO [Member] Outstanding at the end of year, Aggregate Intrinsic Value Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Intrinsic Value Letters of credit outstanding, amount Letters of Credit Outstanding, Amount Other interest income Interest Income, Other Preferred shares, percentage Preferred Stock, Dividend Rate, Percentage Subsidiary, Sale of Stock [Axis] Sale of Stock [Axis] Award Type [Domain] Award Type [Domain] 2026 Lessee, Operating Lease, Liability, to be Paid, Year One Remaining capacity to issue Remaining Capacity To Issue Remaining $ Capacity Of Shares To Issue Noncontrolling interests Equity, Attributable to Noncontrolling Interest Equity Awards Adjustments Equity Awards Adjustments [Member] Other, net Other Noncash Income (Expense) Thereafter Below Market Lease, Amortization Income, after Year Five Other liabilities and deferred credits Deferred Credits and Other Liabilities Pension Benefits Adjustments, Footnote Pension Benefits Adjustments, Footnote [Text Block] Various Hoboken (12 Buildings) Hoboken 14 Buildings [Member] Hoboken 14 Buildings [Member] [Member] Conversion price per share Convertible Preferred Stock, Conversion Price Per Share Convertible Preferred Stock, Conversion Price Per Share Perring Plaza Perring Plaza [Member] Perring Plaza [Member] Decrease (increase) in accounts receivable, net Increase (Decrease) in Accounts and Other Receivables Compensation Amount Outstanding Recovery Compensation Amount Debt Instrument Debt Instrument, Name [Domain] Expected dividend yield Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Dividend Rate Real Estate Disclosure Real Estate Disclosure [Text Block] Straight-line rent Straight Line Rent Recovery of Erroneously Awarded Compensation Disclosure [Line Items] Fair Value Estimate of Fair Value Measurement [Member] Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract] Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract] MNPI Disclosure Timed for Compensation Value MNPI Disclosure Timed for Compensation Value [Flag] Capitalized lease costs amortization range Capitalized lease costs amortization range Capitalized lease costs amortization range Greenwich Avenue Greenwich Avenue [Member] Greenwich Avenue [Member] REVENUE Revenues [Abstract] Encumbrances SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Amount of Encumbrances Accumulated other comprehensive income Accumulated Other Comprehensive Income (Loss), Net of Tax Interest Rate Two Interest Rate Two [Member] Interest Rate Two [Member] 1.25% notes 1.25% Senior Note [Member] 1.25% Senior Note Pike 7 Plaza Pike 7 [Member] Pike 7 [Member] 2026 Long-Term Debt, Maturity, Year One Langhorne Square Langhorne Square [Member] Langhorne Square [Member] 2030 Long-Term Debt, Maturity, Year Five Aggregate Pension Adjustments Service Cost Aggregate Pension Adjustments Service Cost [Member] Wynnewood Wynnewood [Member] Wynnewood [Member] Various Various Notes Payable [Member] Various Notes Payable [Member] Real Estate Investments by Property Type [Axis] Real Estate Investments by Property Type [Axis] Real Estate Investments by Property Type [Axis] Effect of Fourth Quarter Events, Type [Domain] Effect of Fourth Quarter Events, Type [Domain] Statement of Financial Position Location, Activity, Capitalization [Domain] Statement of Financial Position Location, Activity, Capitalization [Domain] Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets by Major Class [Axis] Minimum Minimum [Member] Distribution equivalent rights Disribution equivalent rights Disribution equivalent rights THE AVENUE at White Marsh THE AVENUE at White Marsh [Member] THE AVENUE at White Marsh [Member] 5.375 Senior notes 5.375 Senior notes [Member] 5.375 Senior notes Federal Realty OP LP Partnership Interest [Member] Garden Market Garden Market [Member] Garden Market [Member] Company Selected Measure Name Company Selected Measure Name Capital Improvement, Development, and Redevelopment Projects Capital Improvement, Development, And Redevelopment Projects [Member] Capital Improvement, Development, And Redevelopment Projects [Member] Distributions & redemptions Redeemable noncontrolling interest, Decrease from Distributions and Purchases to redeemable noncontrolling interest holders Redeemable noncontrolling interest, Decrease from Distributions and Purchases to redeemable noncontrolling interest holders Portion at Fair Value Measurement Fair Value Measurement [Domain] Preferred units, issued Preferred Units, Issued Debt Disclosure [Text Block] Debt Disclosure [Text Block] Aggregate Available Trading Arrangement, Securities Aggregate Available Amount Stock Issuance Costs by Type [Axis] Stock Issuance Costs by Type [Axis] Stock Issuance Costs by Type [Axis] Operating cash flows for operating leases Operating Lease, Payments Limited liability company ownership interest Limited Liability Company (LLC) or Limited Partnership (LP), Managing Member or General Partner, Ownership Interest Stock Appreciation Rights (SARs) Stock Appreciation Rights (SARs) [Member] Dividends payable Dividends Payable Additional borrowings exercised additional borrowings exercised additional borrowings exercised Westgate Center Westgate Mall [Member] Westgate Mall [Member] Stockholders' Equity Note [Abstract] Stockholders' Equity Note [Abstract] Repayment of senior notes Repayments of Senior Debt COMMITMENTS AND CONTINGENCIES Commitments and Contingencies Disclosure [Text Block] Weighted average number of common shares Weighted average common shares outstanding—diluted Weighted Average Number of Shares Outstanding, Diluted Segment Information Segment Reporting, Policy [Policy Text Block] Conversion and redemption of downREIT OP units (in shares) Stock Issued During Period, Shares, Conversion of Units Non-GAAP Measure Description Non-GAAP Measure Description [Text Block] Distributions declared to common unit holders Distributions declared to common unit holders Distributions declared to common unit holders Annapolis Town Center Annapolis Town Center [Member] Annapolis Town Center Entity Small Business Entity Small Business Commissions related to sales of common shares Payments of Stock Issuance Costs Net income attributable to redeemable noncontrolling interests Net income Net Income (Loss) Attributable to Redeemable Noncontrolling Interest Second mortgage on a retail shopping center in Baltimore, MD Second mortgage on a retail shopping center in Baltimore, MD [Member] Second mortgage on a retail shopping center in Baltimore, MD Weighted average common units outstanding—diluted weighted average number partnership units outstanding, diluted weighted average number partnership units outstanding, diluted Rental expenses Other Cost and Expense, Operating Subsidiary of LLC or LP [Table] Subsidiary of LLC or LP [Table] Preferred shares, outstanding Preferred Stock, Shares Outstanding Preferred Stock, Shares Outstanding 2030 Below Market Lease, Amortization Income, Year Five Document Transition Report Document Transition Report Total interest costs incurred Interest Costs Incurred Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items] Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items] Total future minimum finance lease payments Finance Lease, Liability, to be Paid Underlying Securities Award Underlying Securities Amount Statement of Partners' Capital [Abstract] Equity Component [Domain] Equity Component [Domain] Document Period End Date Document Period End Date Share type [Axis] Share type [Axis] Share type Contractual obligations Contractual Obligation Awards Close in Time to MNPI Disclosures, Table Awards Close in Time to MNPI Disclosures [Table Text Block] Cash in excess of the FDIC insured limit Cash, Uninsured Amount Net income, excluding amount attributable to redeemable noncontrolling interests Profit Loss Excluding Redeemable Noncontrolling Interests Net income (loss) excluding portion attributable to redeemable noncontrolling interests. Exercisable at the end of year, Weighted-Average Remaining Contractual Term (in years) Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term Total shareholders’ equity Beginning balance Ending balance Equity, Including Portion Attributable to Noncontrolling Interest Mortgage notes receivable, net Mortgage Loans on Real Estate, Commercial and Consumer, Net Document Type Document Type Fair Value, Inputs, Level 3 Fair Value, Inputs, Level 3 [Member] EARNINGS PER SHARE Earnings Per Share [Text Block] Name Outstanding Recovery, Individual Name Loss Contingencies [Table] Loss Contingencies [Table] Notes payable, net Total notes payable, net Notes Payable Variable lease cost Variable Lease, Cost Above market leases Finite-Lived Intangible Assets Acquired Statistical Measurement [Axis] Statistical Measurement [Axis] Pike & Rose Pike & Rose [Member] Pike & Rose Forfeited or Expired, Weighted-Average Exercise Price (in dollars per share) Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Forfeitures and Expirations in Period, Weighted Average Exercise Price Share repurchase program, shares approved (in shares) Share Repurchase Program, Authorized, Amount Mercer One One (formerly known as Mercer Mall) Mercer Mall [Member] Mercer Mall [Member] Fixed interest rate of derivative instrument Fixed interest rate of derivative instrument Derivative, Fixed Interest Rate Aggregate Erroneous Compensation Amount Aggregate Erroneous Compensation Amount Face Amount of Mortgages SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate, Face Amount of Mortgages Senior notes and debentures Senior Notes And Debentures [Member] Senior Notes And Debentures [Member] Shares issued under dividend reinvestment plan Dividends Reinvested in Noncash Financing Transaction Dividends reinvested in noncash financing transaction Shares withheld for employee taxes Payment, Tax Withholding, Share-Based Payment Arrangement Purchase of capped calls Purchase of capped calls Capped call premium Capped call premium Net real estate assets of consolidated VIEs VariableInterestEntity, net Real Estate Assets VariableInterestEntity, net Real Estate Assets Mortgage interest income Revenue Mortgage Interest Interest income earned from mortgage notes receivable. Peer Group Issuers, Footnote Peer Group Issuers, Footnote [Text Block] NET INCOME AVAILABLE FOR COMMON SHAREHOLDERS Net Income (Loss) Available to Common Stockholders, Basic Entity Information [Line Items] Entity Information [Line Items] Preferred units, percentage Preferred unit distribution rate percentage Preferred unit distribution rate percentage Reconciliation of property operating income to consolidated net income Reconciliation of Operating Profit (Loss) from Segments to Consolidated [Table Text Block] Tower Shopping Center Tower [Member] Tower [Member] Total operating expenses Operating Expenses 401(k) Employer match Deferred Compensation Arrangement with Individual, Employer Contribution Per Employee, Matching Percent Deferred Compensation Arrangement with Individual, Employer Contribution Per Employee, Matching Percent Fair Value, Inputs, Level 1 Fair Value, Inputs, Level 1 [Member] Revolving credit facility Long-Term Line of Credit Beginning balance (in shares) Ending balance (in shares) Shares, Outstanding North Dartmouth North Dartmouth [Member] North Dartmouth [Member] Net income available for common shareholders Earnings Per Share, Diluted Noncontrolling Interests in Consolidated Partnerships Noncontrolling Interests in Consolidated Partnerships [Member] Nonredeemable Noncontrolling Interests in Consolidated Partnerships Prepaid expenses and other assets Prepaid expenses and other assets [Line Items] Prepaid expenses and other assets 2030 Lessor, Operating Lease, Payment to be Received, Year Five Weighted average number of common units Weighted average common units outstanding, diluted Weighted average common units outstanding, diluted NON-CASH INVESTING AND FINANCING TRANSACTIONS: Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract] Schedule IV - Mortgage Loans on Real Estate SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Text Block] Total Capital Beginning balance Ending balance Partners' Capital, Including Portion Attributable to Noncontrolling Interest Dividends declared to preferred shareholders Dividends, Preferred Stock, Cash Shares repurchased (in shares) Treasury Stock, Common, Shares Shares issued under dividend reinvestment plan Stock Issued During Period, Value, Dividend Reinvestment Plan Real Estate and Accumulated Depreciation [Line Items] SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items] Preferred shares, capital gain Preferred shares, capital gain Preferred shares, capital gain Town Center Crossing/Town Center Plaza Town Center Crossing/Town Center Plaza [Member] Town Center Crossing/Town Center Plaza Auditor Location Auditor Location 2029 Below Market Lease, Amortization Income, Year Four Twinbrooke Centre Twinbrooke Shopping Centre [Member] Twinbrooke Shopping Centre Northeast Northeast [Member] Northeast [Member] Net increase in rental expense Amortization Of Above And Below Market Leases, Lessee Amortization Of Above And Below Market Leases, Lessee Adjustment to redeemable noncontrolling interests Stockholders' Equity, Other Less amount representing interest Lessee, Operating Lease, Liability, Undiscounted Excess Amount Riverpoint Center Riverpoint Center [Member] Riverpoint Center [Member] Cash paid for income taxes Income Taxes Paid, Net Birch & Broad Falls Plaza [Member] Falls Plaza [Member] 2027 Finite-Lived Intangible Asset, Expected Amortization, Year Two Mortgages and notes payable Principal balance Long-Term Debt, Gross Granted, Weighted-Average Exercise Price (in dollars per share) Share-Based Compensation Arrangements by Share-Based Payment Award, Options, Grants in Period, Weighted Average Exercise Price Entity Well-known Seasoned Issuer Entity Well-known Seasoned Issuer Total future minimum operating lease payments Lessee, Operating Lease, Liability, to be Paid White Marsh Other (portion) A portion of White Marsh Other [Member] A portion of White Marsh Other 7.48% debentures Debentures 7.48 Percent [Member] Debentures 7.48 Percent [Member] Distributions declared to noncontrolling interests, excluding amounts attributable to redeemable noncontrolling interests Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders Third Street Promenade and a portion of White Marsh Other Third Street Promenade and White Marsh Other [Member] Third Street Promenade and White Marsh Other Expiration Date Trading Arrangement Expiration Date Above Market Leases, Lessor AboveMarketLeasesLessor [Member] Above Market Leases, Lessor Village at Shirlington Shirlington [Member] Shirlington [Member] Accumulated Depreciation and Amortization Balance at beginning of year Balance at end of year SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation Santana Row (one residential building) Santana Row (one residential building) [Member] Santana Row (one residential building) Contributions Contributions from redeemable noncontrolling interests Contributions from redeemable noncontrolling interests Bethesda Row Bethesda Row [Member] Bethesda Row [Member] 2030 Finite-Lived Intangible Asset, Expected Amortization, Year Five Common shares, capital gain Common shares, capital gain Common shares, capital gain Shareholders’ equity Equity, Including Portion Attributable to Noncontrolling Interest [Abstract] Gain on sale of real estate Gain on sale of real estate Gain on sale of real estate Gain on sale of real estate Compensation Actually Paid vs. Net Income Compensation Actually Paid vs. Net Income [Text Block] Melville Mall MelvilleMall [Member] MelvilleMall [Member] Entity Current Reporting Status Entity Current Reporting Status Option Indexed to Issuer's Equity, Type [Axis] Option Indexed to Issuer's Equity, Type [Axis] Awards Close in Time to MNPI Disclosures Awards Close in Time to MNPI Disclosures [Table] Consolidated Entities [Domain] Consolidated Entities [Domain] Statement of Financial Position [Abstract] Statement of Financial Position [Abstract] Executive Category: Executive Category [Axis] Granted (in shares) Number of options granted in period Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Grants in Period, Net of Forfeitures Carrying Amount of Mortgages Balance at beginning of year Balance at end of year SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate Hoboken (24 Buildings) Hoboken (24 Buildings) [Member] Hoboken (24 Buildings) Prepaid expenses and other assets [Table] Prepaid expenses and other assets [Table] Prepaid expenses and other assets [Table] Weighted average borrowings outstanding Line of Credit Facility, Average Outstanding Amount Noncontrolling interests in consolidated partnerships Partners' Capital Attributable to Noncontrolling Interest Interest expense Interest expense Interest expense Interest Expense, Operating and Nonoperating Current Fiscal Year End Date Current Fiscal Year End Date Expected term (in years) Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Term Common units withheld for employee taxes Partners capital account employee tax withholdings Partners capital account employee tax withholdings Other operating Other Cost of Operating Revenue Exchange rate principal amount Debt Conversion, Converted Instrument, Amount Finite-Lived Intangible Assets, Major Class Name [Domain] Finite-Lived Intangible Assets, Major Class Name [Domain] Derivative Liability Derivative Liability Accumulated dividends in excess of net income Accumulated Distributions in Excess of Net Income Weighted average grant date fair value of options granted Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value Equity Awards Adjustments, Excluding Value Reported in Compensation Table Equity Awards Adjustments, Excluding Value Reported in the Compensation Table [Member] Willow Grove Willow Grove [Member] Willow Grove [Member] Flourtown Flourtown [Member] Flourtown [Member] Material unrecognized tax benefits Unrecognized Tax Benefits Net proceeds Proceeds from Debt, Net of Issuance Costs Anti-dilutive issuable shares Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Net income available for common unit holders Net income available for common unit holders, diluted Net income available for common unit holders, diluted Deferred compensation liability to participants Deferred Compensation Arrangement with Individual, Recorded Liability Fair Value, by Balance Sheet Grouping [Table] Fair Value, by Balance Sheet Grouping [Table] 2027 Long-Term Debt, Maturity, Year Two Net cash provided by (used in) financing activities Cash Provided by (Used in) Financing Activity, Including Discontinued Operation Measure: Measure [Axis] Total rental expenses Direct Costs of Leased and Rented Property or Equipment Other comprehensive (loss) income - change in value of interest rate swaps Other Comprehensive Income (Loss) Attributable to Redeemable Noncontrolling Interests Other Comprehensive Income (Loss) Attributable to Redeemable Noncontrolling Interests Prior Liens SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate, Prior Lien, Amount Thereafter Finite-Lived Intangible Asset, Expected Amortization, after Year Five Old Town Center Old Town Center [Member] Old Town Center [Member] Property, Plant and Equipment, Type [Domain] Long-Lived Tangible Asset [Domain] Capital expenditures - other Capital expenditures other Capital expenditures other Add: Income attributable to downREIT operating partnership units Income attributable to downREIT operating partnership units Income attributable to downREIT operating partnership units Schedule III - Summary of Real Estate and Accumulated Depreciation SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation Disclosure [Text Block] Pay vs Performance Disclosure, Table Pay vs Performance [Table Text Block] Real Estate and Accumulated Depreciation, Carrying Amount of Land and Buildings and Improvements [Abstract] SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Gross [Abstract] Forgone Recovery due to Violation of Home Country Law, Amount Forgone Recovery due to Violation of Home Country Law, Amount Second Mortgage on a retail shopping center in Rockville, MD One Second Mortgage on a retail shopping center in Rockville, MD One [Member] Second Mortgage on a retail shopping center in Rockville, MD One Risk free interest rate Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Risk Free Interest Rate Debt issuance cost amortization Amortization of Debt Issuance Costs IRS Employer Identification No. Entity Tax Identification Number Number of real estate properties Number of Real Estate Properties Outstanding at the beginning of year, Weighted-Average Exercise Price (in dollars per share) Outstanding at the end of year, Weighted-Average Exercise Price (in dollars per share) Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Weighted Average Exercise Price Reconsolidation of VIE Reconsolidation of VIE Reconsolidation of VIE Common shares of beneficial interest, shares issued Common Stock, Shares, Issued Chandler Gateway Chandler Gateway [Member] Chandler Gateway Weighted-average remaining lease term - operating leases Operating Lease, Weighted Average Remaining Lease Term 2029 Long-Term Debt, Maturity, Year Four Rollforward table of the redeemable noncontrolling interest Redeemable Noncontrolling Interest [Table Text Block] Number of consolidated variable interest entities Number of Consolidated Variable Interest Entities Number of consolidated entities that meet the criteria of a variable interest entity in which the Company holds a variable interest under ASU 2015-02. The Grove at Shrewsbury The Grove at Shrewsbury [Member] The Grove at Shrewsbury [Member] Entity Public Float Entity Public Float Bala Cynwyd on City Avenue Bala Cynwyd [Member] Bala Cynwyd [Member] Trading Arrangement: Trading Arrangement [Axis] Purchase of capped calls Partners' Capital Account, Capped call premiums Partners' Capital Account, Capped call premiums Total Shareholder Return Amount Total Shareholder Return Amount Percentage of cap price premium over share price Capped call premium percentage Capped call premium percentage Rental income Operating Lease, Lease Income Mortgage Loans on Real Estate, Description, Type of Property [Axis] Real Estate, Type of Property [Axis] Loss Contingencies [Line Items] Loss Contingencies [Line Items] Security Exchange Name Security Exchange Name Aggregate offering price of common shares Aggregate Offering Price Of Common Share Maximum aggregate offering price of common shares. Share repurchase program, par value (in dollars per share) Share repurchase program, par value per share Share repurchase program, par value per share 2027 Lessor, Operating Lease, Payment to be Received, Year Two SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items] SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items] Performance Incentive Plan 2010 Performance Incentive Plan 2010 [Member] Performance Incentive Plan 2010 [Member] Anti-dilutive issuable units Antidilutive Securities Excluded from Computation of Net Income, Per Outstanding Unit, units Antidilutive Securities Excluded from Computation of Net Income, Per Outstanding Unit, units Maximum borrowing capacity under revolving credit facility Line of Credit Facility, Maximum Borrowing Capacity Shares issued under dividend reinvestment plan (in shares) Stock Issued During Period, Shares, Dividend Reinvestment Plan Greenlawn Plaza Greenlawn Plaza [Member] Greenlawn Plaza Share-based compensation expense, net of forfeitures Partners' Capital Account, Unit-Based Payment Arrangement, Amount EXPENSES Operating Expenses [Abstract] Rollforward of Redeemable Noncontrolling Interests Increase (Decrease) in Temporary Equity [Roll Forward] Statement [Line Items] Statement [Line Items] Rule 10b5-1 Arrangement Adopted Rule 10b5-1 Arrangement Adopted [Flag] Cash and cash equivalents Cash and Cash Equivalent The Shops at Hilton Village Hilton Village [Member] Hilton Village Subsequent Event [Line Items] Subsequent Event [Line Items] Common shares Common Stock [Member] Vested (in shares) Vested (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Vested in Period Summary of dividends declared and paid per share Schedule of Dividends Declared and Paid Per Share [Table Text Block] Schedule of Dividends Declared and Paid Per Share [Table Text Block] Finance Lease, Liability, Payment, Due [Abstract] Finance Lease, Liability, to be Paid, Fiscal Year Maturity [Abstract] Less accumulated depreciation and amortization (including $468,725 and $424,044 of consolidated variable interest entities, respectively) Real Estate Investment Property, Accumulated Depreciation Stock options Stock options [Member] Stock options (Decrease) increase in cash, cash equivalents, and restricted cash Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Period Increase (Decrease), Including Exchange Rate Effect and Discontinued Operation Common shares, paid Common Stock, Dividends, Per Share, Cash Paid SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Significant Accounting Policies [Text Block] $250M Term Loan $250M Term Loan [Member] $250M Term Loan Statistical Measurement [Domain] Statistical Measurement [Domain] Thereafter Lessee, Operating Lease, Liability, to be Paid, after Year Five Purchase price under option Purchase Price Under Option Purchase Price Under Option Interest Rate One Interest Rate One [Member] Interest Rate One [Member] Reserves for warranties and general liability Standard and Extended Product Warranty Accrual Mortgage Loans on Real Estate, Name, Property Type [Domain] Real Estate [Domain] Interest Rate Swap Interest Rate Swap [Member] Debt Issuance Costs Debt, Policy [Policy Text Block] Income from partnerships Income from partnerships Income (Loss) from Equity Method Investments Leases [Abstract] Leases [Abstract] EARNINGS PER COMMON SHARE, BASIC Earnings Per Share, Basic [Abstract] 2029 Lessor, Operating Lease, Payment to be Received, Year Four Intangible Asset, Acquired, Finite-Lived [Line Items] Intangible Asset, Acquired, Finite-Lived [Line Items] Gross amount at which carried at close of period, Land SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Land, Amount Call Option Call Option [Member] Costs associated with property sold under threat of condemnation Costs associated with lease buyout for a property sold Costs associated with lease buyout for a property sold Shares withheld for employee taxes Share-Based Payment Arrangement, Decrease for Tax Withholding Obligation Federal Realty GP LLC Federal Realty GP LLC [Member] Federal Realty GP LLC Trading Arrangements, by Individual Trading Arrangements, by Individual [Table] 3.20% notes 3.2% Senior Note [Member] 3.2% Senior Note [Member] Net income available for common shareholders Earnings Per Share, Basic Increase in accounts payable and accrued expenses Increase (Decrease) in Accounts Payable and Accrued Liabilities Preferred shares, declared Preferred Stock, Dividends Per Share, Declared Components Of Rental Expense [Abstract] Components Of Rental Expense [Abstract] Components Of Rental Expense [Abstract] Dividends paid to common and preferred unit holders Dividends paid to common and preferred unit holders Dividends paid to common and preferred unit holders Other comprehensive (loss) income - change in value of interest rate swaps Other comprehensive (loss) income Other Comprehensive Income (Loss), Net of Tax Purchase of noncontrolling interest Partners' Capital Account, Purchase of noncontrolling interest Partners' Capital Account, Purchase of noncontrolling interest Segment Reporting, Factors Used to Identify Entity's Reportable Segments Segment Reporting, Factors Used to Identify Entity's Reportable Segments Fresh Meadows Fresh Meadows [Member] Fresh Meadows [Member] Depreciation expense real estate Depreciation Expense Real Estate Depreciation Expense on Real Estate only Kingstowne Towne Center Kingstowne Shopping Center [Member] Kingstowne Shopping Center 2028 Finance Lease, Liability, to be Paid, Year Three Award Timing MNPI Disclosure Award Timing MNPI Disclosure [Text Block] Indexed ownership interest percentage Ownership Interest of Other Partner in Put Option The percentage of partnership interest we are required to purchase in a put option. Payroll Property Payroll Expense Property Payroll Expense related to property management which includes salaries and benefits. Grants of common shares, restricted stock units, and options Share-Based Payment Arrangement, Expense Ground rent Ground Rent Expense Ground Rent Expense Maximum amount of borrowings outstanding Line of Credit Facility, Maximum Amount Outstanding During Period Goodwill and Intangible Assets Disclosure [Abstract] Goodwill and Intangible Assets Disclosure [Abstract] Virginia Gateway Virginia Gateway [Member] Virginia Gateway Mortgages payable, net (including $194,176 and $186,643 of consolidated variable interest entities, respectively) Total mortgage payable, net Secured Debt TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY / CAPITAL Liabilities and Equity Exchange premium percentage Exchange premium percentage Exchange premium percentage Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward] Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding [Roll Forward] Barracks Road Barracks Road [Member] Barracks Road [Member] Friendship Center Friendship Ctr [Member] Friendship Ctr [Member] 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). Elllisburg Elllisburg Circle [Member] Elllisburg Circle [Member] Acquired lease costs Acquired lease costs Acquired lease costs Number of properties exceeding segment reporting threshold Number of Properties Exceeding Segment Reporting Threshold Number of Properties Exceeding Segment Reporting Threshold Deduction during period—dispositions and retirements of property Real Estate Dispositions and Retirements Carrying amount of real estate sold, cap ex disposals, and transfers to joint venture during the period. Prepaid Expenses and Other Assets Prepaid Expenses and Other Assets [Policy Text Block] Description of entity's accounting policy related to prepaid expenses and other assets. Accounting Policies [Abstract] Accounting Policies [Abstract] Preferred units, 398,878 units issued and outstanding Preferred Units, Preferred Partners' Capital Accounts Below market leases Below Market Lease, Acquired Minimum annual payments Lessee, Operating Lease, Liability, to be Paid, Maturity [Table Text Block] Total vesting-date fair value of shares vested during the year Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value Notes Payable Notes Payable gross Notes Payable gross Pay vs Performance Disclosure [Line Items] 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. Operating lease liabilities Operating Lease, Liability Total Lessor, Operating Lease, Payment to be Received Preferred shares, liquidation preference per share Preferred shares, liquidation preference per share Preferred Stock, Liquidation Preference Per Share Liabilities Liabilities [Abstract] SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Abstract] SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Abstract] Depreciation and amortization Depreciation and amortization Depreciation, Depletion and Amortization, Nonproduction Finance Lease, amortization of right-of-use assets Finance Lease, Right-of-Use Asset, Amortization Collection and satisfaction of loans SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate, Collections of Principal Chesterbrook Chesterbrook [Member] Chesterbrook Variable Interest Entity [Table] Variable Interest Entity [Table] Statement of Cash Flows [Abstract] Statement of Cash Flows [Abstract] Company Selected Measure Amount Company Selected Measure Amount 2028 Lessee, Operating Lease, Liability, to be Paid, Year Three Debt Issuance Costs, Gross Debt Issuance Costs, Gross COMPREHENSIVE INCOME ATTRIBUTABLE TO THE TRUST / PARTNERSHIP Comprehensive Income (Loss), Net of Tax, Attributable to Parent Security deposits payable Security Deposit Liability Name Measure Name Mortgages Payable Secured Debt [Member] Class of Stock [Line Items] Class of Stock [Line Items] Fourth Street Fourth Street [Member] Fourth Street [Member] 5.0% Series C Cumulative Redeemable Preferred Shares, (stated at liquidation preference $25,000 per share), 6,000 shares issued and outstanding 5.0% Series C Cumulative Redeemable Preferred Shares 5.0% Series C Cumulative Redeemable Preferred [Member] Five point Zero Percentage Series C Redeemable Convertible Preferred Stock [Member] Long-term Debt Long-Term Debt Accounts and notes receivable, net Accounts and Financing Receivable, after Allowance for Credit Loss Co-Registrant [Axis] Legal Entity [Axis] Federal Plaza Federal Plaza [Member] Federal Plaza [Member] TOTAL ASSETS Assets Performance based unvested restricted stock units Performance Based Unvested Shares [Member] Performance Based Unvested Shares Other Offering Costs Other Offering Costs [Member] Other Offering Costs [Member] Net income available for common unit holders, diluted Net income available for common unit holders, value, diluted Net income available for common unit holders, value, diluted 2026 Finite-Lived Intangible Asset, Expected Amortization, Year One Impairment of property Real estate accumulated depreciation impairment of property Real estate accumulated depreciation impairment of property Vested, Weighted-Average Grant-Date Fair Value (in dollars per share) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value Total partner capital Partners' Capital Income Taxes Income Tax, Policy [Policy Text Block] OPERATING ACTIVITIES Cash Provided by (Used in) Operating Activity, Including Discontinued Operation [Abstract] Acquired lease assets, remaining weighted average amortization period Acquired Finite-Lived Intangible Assets, Weighted Average Useful Life Depreciation and amortization expense SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation, Depreciation Expense Real estate, at cost, total Real Estate Investment Property, at Cost Santana Row Santana Row [Member] Santana Row 2029 Finite-Lived Intangible Asset, Expected Amortization, Year Four Variable Interest Entity [Line Items] Variable Interest Entity [Line Items] Marketing Marketing Expense 2026 Finance Lease, Liability, to be Paid, Year One Variable Interest Entities Consolidation, Variable Interest Entity, Policy [Policy Text Block] Dividends declared to common shareholders (in dollars per share) Dividends declared to common shareholders Common Stock, Dividends, Per Share, Declared Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Assembly Row Hotel Assembly Row Hotel [Member] Assembly Row Hotel 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. First Mortgage on a retail shopping center in Rockville, MD First Mortgage on a retail shopping center in Rockville, MD [Member] First Mortgage on a retail shopping center in Rockville, MD Earnings Per Share Narrative [Table] Earnings Per Share Narrative [Table] Earnings Per Share Narrative [Table] Fair Value, Inputs, Level 2 Fair Value, Inputs, Level 2 [Member] Document Financial Statement Error Correction [Flag] Document Financial Statement Error Correction [Flag] Insider Trading Policies and Procedures Not Adopted Insider Trading Policies and Procedures Not Adopted [Text Block] 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. Plan Name [Axis] Plan Name [Axis] Real Estate Property, Plant and Equipment, Policy [Policy Text Block] PEO PEO [Member] Fairfax Junction Fairfax Junction [Member] Fairfax Junction Changes in assets and liabilities, net of effects of acquisitions and dispositions: Adjustment to Reconcile Net Income to Cash Provided by (Used in) Operating Activity, Increase (Decrease) in Operating Capital [Abstract] Adjacent shopping centers number of adjacent shopping centers number of adjacent shopping centers Volatility Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Volatility Rate Utilities Utilities Operating Expense Share-based Payment Arrangement [Abstract] Share-Based Payment Arrangement [Abstract] Cash, cash equivalents, and restricted cash at beginning of year Cash, cash equivalents, and restricted cash at end of year Total cash, cash equivalents, and restricted cash Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Continuing Operation Income Statement [Abstract] Income Statement [Abstract] Derivative Asset Derivative Asset Preferred shares, paid Preferred Stock, Dividends, Per Share, Cash Paid Sale of Stock, Name of Transaction [Domain] Sale of Stock [Domain] Net income available for common unit holders Net income available for common unit holders Income (Loss) from Continuing Operations, Per Outstanding General Partnership Unit, Net of Tax Above Market Leases Above Market Leases [Member] Aggregate maximum borrowing capacity under accordian feature Aggregate maximum borrowing capacity under accordian feature Aggregate maximum borrowing capacity under accordian feature Dividends [Abstract] Dividends [Abstract] Adjustment to redeemable noncontrolling interests Partners' Capital, Other Total Partner Capital Parent [Member] NET INCOME Net income Net Income (Loss), Including Portion Attributable to Noncontrolling Interest 2028 Lessor, Operating Lease, Payment to be Received, Year Three Restatement does not require Recovery Restatement Does Not Require Recovery [Text Block] Schedule of Significant Acquisitions [Table] Business Combination [Table] Total notional amounts of interest rate swap agreements Derivative, Notional Amount Governor Plaza Governor Plaza [Member] Governor Plaza [Member] 3.625% notes 3.625% Senior notes [Member] 3.625% Senior notes [Member] Hastings Ranch Plaza Hastings Ranch Plaza [Member] Hastings Ranch Plaza San Antonio Center San Antonio Center [Member] San Antonio Center [Member] City Area Code City Area Code Award Timing, How MNPI Considered Award Timing, How MNPI Considered [Text Block] Contributions from noncontrolling interests, excluding amounts attributable to redeemable noncontrolling interests Contributions from noncontrolling interests Contributions from noncontrolling interests Contributions from noncontrolling interests Operating (including $1,832,190 and $1,825,656 of consolidated variable interest entities, respectively) Rental Properties INVESTING ACTIVITIES Cash Provided by (Used in) Investing Activity, Including Discontinued Operation [Abstract] General and administrative General and administrative General and Administrative Expense Pay vs Performance Disclosure Pay vs Performance Disclosure [Table] 401(k) Employer contribution expense Deferred Compensation Arrangement with Individual, Contributions by Employer Other Postretirement Benefits, Individual Contracts, Type of Deferred Compensation [Domain] Other Postretirement Benefits, Individual Contracts, Type of Deferred Compensation [Domain] Total Lease Cost Lease, Cost LEASE COST Lease, Cost [Table Text Block] Escondido Promenade Escondido Promenade [Member] Former Mervyns Parcel, Escondido Promenade [Member] Period for recognition (in years) Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition Years Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition Years Percent of annualized base rent Percent of Annualized Base Rent Maximum Percent of Annualized Base Rent Maximum Real Estate Investments by Property Type [Domain] Real Estate Investments by Property Type [Domain] Real Estate Investments by Property Type [Domain] Brook 35 Brook 35 [Member] Brook 35 [Member] Auditor Name Auditor Name BUSINESS AND ORGANIZATION Nature of Operations [Text Block] Supplemental Cash Flow Information [Abstract] Supplemental Cash Flow Information [Abstract] Other Performance Measure, Amount Other Performance Measure, Amount Chandler Festival Chandler Festival [Member] Chandler Festival Aggregate cost basis for Federal tax purposes SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Federal Income Tax Basis Real Estate Accumulated Depreciation Reconsolidation of VIE Real Estate Accumulated Depreciation Reconsolidation of VIE Real Estate Accumulated Depreciation Reconsolidation of VIE 2026 Lessor, Operating Lease, Payment to be Received, Year One Related Party [Domain] Related and Nonrelated Parties [Domain] Distributions delcared to redeemable noncontrolling interests Redeemable noncontrolling interest, Decrease from Distributions to redeemable noncontrolling interest holders Redeemable noncontrolling interest, Decrease from Distributions to redeemable noncontrolling interest holders Interest capitalized Interest Costs Capitalized Adjustment Derivative Instrument Derivative Instrument [Axis] Convertible Unit Type [Domain] Convertible Unit Type [Domain] Convertible Unit Type [Domain] Additional paid-in capital Additional Paid in Capital, Common Stock Entity [Domain] Entity [Domain] EARNINGS PER COMMON UNIT, BASIC Earnings Per Unit [Abstract] Quarterly common dividend payable, if in excess will adjust the initial Initial quarterly common dividend Initial quarterly common dividend Net cash used in investing activities Cash Provided by (Used in) Investing Activity, Including Discontinued Operation Investment in partnerships Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures Aggregate Change in Present Value of Accumulated Benefit for All Pension Plans Reported in Summary Compensation Table Aggregate Change in Present Value of Accumulated Benefit for All Pension Plans Reported in Summary Compensation Table [Member] Amount reclassified from other comprehensive income to interest expense Interest Rate Cash Flow Hedge Gain (Loss) Reclassified to Earnings, Net Cash paid for interest, net of amounts capitalized Interest Paid, Excluding Capitalized Interest, Operating Activity Distributions declared to preferred unit holders Less: Preferred unit distributions Distributions declared to preferred unit holders Distributions declared to preferred unit holders Document Fiscal Year Focus Document Fiscal Year Focus Operating lease right of use assets, net Operating Lease, Right-of-Use Asset Operating lease cost Operating Lease, Cost Pinole Vista Crossing Pinole Vista Crossing [Member] Pinole Vista Crossing Plan Name [Domain] Plan Name [Domain] Carrying Value Reported Value Measurement [Member] Term Loan Term loan [Member] Term loan [Member] Weighted-average period for recognition Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition Real Estate [Abstract] Real Estate [Abstract] Federal Realty OP LP Federal Realty OP LP [Member] Federal Realty OP LP Exercised (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Exercises in Period Gaithersburg Square Gaithersburg Square [Member] Gaithersburg Square [Member] Senior notes and debentures, net Senior Notes Estimated condemnation proceedings liability Estimated Litigation Liability Chandler Festival and Chandler Gateway Chandler [Member] Chandler 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. Derivative Instruments Derivatives, Policy [Policy Text Block] 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 Acquired Finite-Lived Intangible Asset by Major Class [Table] Schedule of Acquired Finite-Lived Intangible Asset by Major Class [Table] downREIT OP units downREIT OP units [Member] downREIT OP units Total debt Debt and Lease Obligation Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] New market tax credit transaction income New market tax credit transaction income New market tax credit transaction income New market tax credit transaction income Interest Rate Mortgage Loans on Real Estate, Participation Plus Interest Rate, Interest Rate Mortgage Loans on Real Estate, Participation Plus Interest Rate, Interest Rate Compensation Actually Paid vs. Total Shareholder Return Compensation Actually Paid vs. Total Shareholder Return [Text Block] Fair Value, Recurring and Nonrecurring [Table] Fair Value, Recurring and Nonrecurring [Table] Amortization of above market leases, lessor Amortization of Intangible Assets Exchange [Domain] Exchange [Domain] Exchange rate Debt Instrument, Convertible, Conversion Ratio Hauppauge Hauppauge [Member] Hauppauge [Member] Increase (Decrease) in Partners' Capital [Roll Forward] Increase (Decrease) in Partners' Capital [Roll Forward] Revolving credit facility Revolving credit facility Revolving Credit Facility [Member] Straight-line rent receivables Straight line rent receivable Straight line rent receivable Finance lease liabilities Finance lease liabilities Finance Lease, Liability Arrangement Duration Trading Arrangement Duration SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate, Other Disclosure [Abstract] SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate, Other Disclosure [Abstract] Above Market Leases, Lessee Above Market Leases, Lessee [Member] Above Market Leases, Lessee [Member] DownREIT operating partnership units Common shares attributable to dilutive effect of downREIT operating partnership units Common shares attributable to dilutive effect of downREIT operating partnership units Local Phone Number Local Phone Number Additional 402(v) Disclosure Additional 402(v) Disclosure [Text Block] Share price Share Price Thereafter Long-Term Debt, Maturity, after Year Five SHARE-BASED COMPENSATION PLANS Share-Based Payment Arrangement [Text Block] Del Monte Shopping Center Del Monte Shopping Center [Member] Del Monte Shopping Center Distributions declared to noncontrolling interests in consolidated partnerships, excluding amounts attributable to redeemable noncontrolling interests Distributions declared to noncontrolling interests in consolidated partnerships, excluding amounts attributable to redeemable noncontrolling interests Distributions declared to noncontrolling interests in consolidated partnerships, excluding amounts attributable to redeemable noncontrolling interests Plaza El Segundo/The Point Plaza El Segundo/The Point [Member] Plaza El Segundo/The Point ASSETS Assets [Abstract] Insurance Real Estate Insurance Credit Facility [Axis] Credit Facility [Axis] Underlying Security Market Price Change Underlying Security Market Price Change, Percent Debt Instrument [Axis] Debt Instrument [Axis] Forfeited, Weighted-Average Grant-Date Fair Value (in dollars per share) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value SAVINGS AND RETIREMENT PLANS Retirement Benefits [Text Block] FAIR VALUE OF FINANCIAL INSTRUMENTS Fair Value Disclosures [Text Block] Business Acquisition and Disposition Business Combination [Line Items] Credit Facility [Domain] Credit Facility [Domain] Property operating income Property operating income Property operating income Acquired Lease Liabilities Below Market Lease, Amortization Income, Maturity Schedule [Abstract] Interest rate Debt Instrument, Interest Rate, Stated Percentage Real Estate Properties [Domain] Real Estate Properties [Domain] Payment of ordinary dividends, preferred stock Preferred Stock, Ordinary Dividends, Per Share, Cash Paid Preferred Stock, Ordinary Dividends, Per Share, Cash Paid Entity Voluntary Filers Entity Voluntary Filers Partners' Capital Partners' Capital [Abstract] Net income available for common unit holders, basic Net income available for common unit holders, basic Net income available for common unit holders, basic Congressional Plaza Congressional Plaza [Member] Congressional Plaza [Member] Entity Registrant Name Entity Registrant Name Acquired lease liabilities, remaining weighted average amortization period Acquired Finite-Lived Intangible Liabilities, Weighted Average Useful Life Acquired Finite-Lived Intangible Liabilities, Weighted Average Useful Life Stock Price or TSR Estimation Method Stock Price or TSR Estimation Method [Text Block] New York Stock Exchange, Inc. NEW YORK STOCK EXCHANGE, INC. [Member] Convertible Unit Type [Axis] Convertible Unit Type [Axis] Convertible Unit Type Share type [Domain] Share type [Domain] Share type [Domain] Old Keene Mill Old Keene Mill [Member] Old Keene Mill [Member] Other comprehensive income (loss) - change in value of interest rate swaps, excluding amounts attributable to redeemable noncontrolling interest Other Comprehensive Income (loss), net of portion attributable to noncontrolling interest Other Comprehensive Income (loss), net of portion attributable to noncontrolling interest Initial cap price Capped call cap share price Capped call cap share price Finley Square Finley Square [Member] Finley Square [Member] Real Estate Property Ownership [Axis] Real Estate Property Ownership [Axis] Granted, Weighted-Average Grant-Date Fair Value (in dollars per share) Weighted-average grant-date fair value of stock awarded Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value Related Party [Axis] Related and Nonrelated Parties [Axis] Chelsea Chelsea Commons Chelsea [Member] Chelsea [Member] Summary of Acquired Lease Assets and Liabilities Schedule of Finite-Lived Intangible Assets [Table Text Block] Restatement Determination Date: Restatement Determination Date [Axis] Revenue Recognition and Accounts Receivable Revenue Recognition and Accounts Receivable [Policy Text Block] Disclosure of accounting policy for revenue recognition for operating leases and trade and other accounts receivable. Includes how an entity determines the level of its allowance for doubtful accounts. Mortgage Notes Receivable Financing Receivable, Held-for-Investment [Policy Text Block] Summary of our outstanding interest rate swap agreements on consolidated debt Schedule of Interest Rate Derivatives [Table Text Block] Interest expense Interest Expense, Debt Leasing costs Increase (Decrease) in Lease Acquisition Costs Summary of financial assets/(liabilities) measured at fair value on a recurring basis Fair Value, Liabilities Measured on Recurring Basis [Table Text Block] Name Trading Arrangement, Individual Name Conversion and redemption of downREIT OP units Stock Issued During Period, Value, Conversion of Units Finite-Lived Intangible Liabilities By Major Class [Domain] Finite-Lived Intangible Liabilities By Major Class [Domain] [Domain] for Finite-Lived Intangible Liabilities By Major Class [Axis] Purchase of noncontrolling interest Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests Quince Orchard Quince Orchard Plaza [Member] Quince Orchard Plaza [Member] Operating partnership units outstanding, fair value Operating Partnership Units Fair Value Fair value of operating partnership units at the balance sheet date. Preferred Shares Preferred Stock [Member] Barcroft Plaza Barcroft Plaza [Member] Barcroft Plaza Less: Earnings allocated to unvested shares Earnings Allocated To Unvested Shares Earnings allocated to unvested shares Olivo at Mission Hills Olivo at Mission Hills [Member] Olivo at Mission Hills [Member] Acquired lease liabilities, Cost Finite-Lived Intangible Liabilities, Gross Finite-Lived Intangible Liabilities, Gross Name Awards Close in Time to MNPI Disclosures, Individual Name Unvested at the beginning of year, Weighted-Average Grant-Date Fair Value (in dollars per share) Unvested at the end of year, Weighted-Average Grant-Date Fair Value (in dollars per share) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value Aggregate Erroneous Compensation Not Yet Determined Aggregate Erroneous Compensation Not Yet Determined [Text Block] ICFR Auditor Attestation Flag ICFR Auditor Attestation Flag Assembly Row/Assembly Square Market Place Assembly Square Market Place Assembly Row [Member] Assembly Square Market Place Assembly Row [Member] 401(k) Maximum of employer match as a percentage of employee eligible earnings Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay Deductions during period—dispositions and retirements of property Real Estate Accumulated Depreciation Dispositions and Retirements Real Estate Accumulated Depreciation Dispositions and Retirements Finance Lease, Liability, Fiscal Year Maturity Finance Lease, Liability, to be Paid, Maturity [Table Text Block] Performance Incentive Plan 2020 Performance Incentive Plan 2020 [Member] Performance Incentive Plan 2020 Auditor Firm ID Auditor Firm ID Plaza El Segundo Plaza El Segundo [Member] Plaza El Segundo [Member] Acquired lease liabilities, Accumulated Amortization Finite-Lived Intangible Liabilities, Accumulated Amortization Finite-Lived Intangible Liabilities, Accumulated Amortization 2025 Property Acquisitions and Dispositions 2025 Property Acquisitions and Dispositions [Table Text Block] 2025 Property Acquisitions and Dispositions Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV [Domain] Statement of Financial Position Location, Balance [Domain] Statement of Financial Position Location, Balance [Domain] Unconsolidated Unconsolidated variable interest entities Unconsolidated Properties [Member] Schedule of principal components of rental expenses Schedule Of Principal Components Of Rental Expenses [Table Text Block] Schedule Of Principal Components Of Rental Expenses [Table Text Block] Senior Notes and Debentures Senior Notes [Member] Summary of Acquired Lease Amortization Finite-Lived Intangible Assets Amortization Expense [Table Text Block] Preferred shares, authorized 15,000,000 shares, $0.01 par: Preferred Stock, Value, Issued All Executive Categories All Executive Categories [Member] Common shares of beneficial interest, $0.01 par, 200,000,000 shares authorized, 86,266,009 and 85,666,220 shares issued and outstanding, respectively Common Stock, Value, Issued Finance lease right of use assets, net Finance Lease, Right-of-Use Asset, after Accumulated Amortization Exchangeable Senior Notes Exchangeable Senior Notes [Policy Text Block] Exchangeable Senior Notes Other comprehensive (loss) income attributable to Redeemable Noncontrolling interest Other comprehensive income (loss) attributable to Redeemable Noncontrolling interest Other comprehensive income (loss) attributable to redeemable noncontrolling interest Title and Position [Axis] Title and Position [Axis] Commitments and contingencies (Note 7) Commitments and Contingencies No Trading Symbol Flag No Trading Symbol Flag Share-based Payment Arrangement, Expensed and Capitalized, Amount [Abstract] Share-Based Payment Arrangement, Recognized Amount [Abstract] 4.50% notes 4.50% Senior notes [Member] 4.50% Senior notes COMPREHENSIVE INCOME Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest Camelback Colonnade and The Shops at Hilton Village Camelback Colonnade and Hilton Village [Member] Camelback Colonnade and Hilton Village Issuance of common units, net of costs Issuance of common units, net of costs Issuance of common units, net of costs Below Market Leases, Lessor BelowMarketLeasesLessor [Member] Below Market Leases, Lessor Noncontrolling Interests Noncontrolling Interest [Member] Recent Accounting Pronouncements Accounting Standards Update and Change in Accounting Principle [Text Block] White Marsh Plaza White Marsh Plaza [Member] White Marsh Plaza [Member] Thereafter Lessor, Operating Lease, Payment to be Received, after Year Five Distribution from partnerships in excess of earnings Proceeds from Distributions Received from Real Estate Partnerships PEO Actually Paid Compensation Amount PEO Actually Paid Compensation Amount Forfeited or expired (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Forfeitures and Expirations in Period EARNINGS PER COMMON SHARE, DILUTED Earnings Per Share, Diluted [Abstract] Dedham Plaza Dedham Plaza [Member] Dedham Plaza [Member] Audit Information [Abstract] Audit Information [Abstract] Scenario [Axis] Scenario [Axis] Forward Equity Sales Policy Forward Equity Sales Policy [Policy Text Block] Forward Equity Sales Policy Derivative, Name [Domain] Derivative Contract [Domain] Issuance of common shares, net of costs Net cash proceeds of common stock Proceeds from Issuance of Common Stock Debt Instruments [Abstract] Debt Instruments [Abstract] All Individuals All Individuals [Member] Residential Residential Real Estate [Member] Weighted average interest rate on mortgage note receivables WeightedAverageInterestRateonFinancingReceivable The weighted average interest rate on outstanding financing recievables Long-term Debt, Type Long-Term Debt, Type [Domain] Fair Value Disclosures [Abstract] Fair Value Disclosures [Abstract] Name Forgone Recovery, Individual Name Contractual term (in years) Share-Based Compensation Arrangement by Share-Based Payment Award, Expiration Period Redeemable Noncontrolling Interests Redeemable Noncontrolling Interests [Policy Text Block] Redeemable Noncontrolling Interests [Policy Text Block] Year-over-Year Change in Fair Value of Equity Awards Granted in Prior Years That are Outstanding and Unvested Year-over-Year Change in Fair Value of Equity Awards Granted in Prior Years That are Outstanding and Unvested [Member] Deferred Compensation Arrangement with Individual, Postretirement Benefit [Table] Deferred Compensation Arrangement with Individual, Postretirement Benefit [Table] Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract] Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Continuing Operation [Abstract] Nature of Operations Subsidiary of Limited Liability Company or Limited Partnership [Line Items] One of our equity method investees Equity Method Investee [Member] First mortgage on a retail shopping center in Baltimore, MD First mortgage on a retail shopping center in Baltimore, MD [Member] First mortgage on a retail shopping center in Baltimore, MD Schedule of interest rate swap agreements Schedule of Derivative Instruments [Table Text Block] Erroneous Compensation Analysis Erroneous Compensation Analysis [Text Block] Idylwood Plaza Idylwood Plaza [Member] Idylwood Plaza [Member] DownREIT operating partnership units redeemed for common shares Redemptionofoperatingpartnershipunitsforcommonshares Redemption of operating partnership units for common shares Rule 10b5-1 Arrangement Terminated Rule 10b5-1 Arrangement Terminated [Flag] Azalea Azalea [Member] Azalea [Member] Effect of Fourth Quarter Event Type [Axis] Effect of Fourth Quarter Event Type [Axis] OPERATING LEASES Lessor, Operating Leases [Text Block] Westpost Westpost [Member] Westpost Scenario, Forecast Forecast [Member] Erroneously Awarded Compensation Recovery Erroneously Awarded Compensation Recovery [Table] Weighted average price per common share Weighted Average Price Per Common Share Weighted average price per common share Title of 12(b) Security Title of 12(b) Security SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate Schedule [Table] SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate Schedule [Table] COMPREHENSIVE INCOME Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent [Abstract] Spread adjustment Spread adjustment Spread adjustment Shops at Pembroke Gardens Shops at Pembroke Gardens [Member] Shops at Pembroke Gardens Officer Officer [Member] Earnings Per Share [Abstract] Earnings Per Share [Abstract] 2030 Lessee, Operating Lease, Liability, to be Paid, Year Five Subsidiary, Ownership Percentage, Parent Subsidiary, Ownership Percentage, Parent Camelback Colonnade Camelback Colonnade [Member] Camelback Colonnade Thereafter Finance Lease, Liability, to be Paid, after Year Five Exercised, Weighted-Average Exercise Price (in dollars per share) Share-Based Compensation Arrangements by Share-Based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price 6.82% medium term notes Medium Term Notes 6.82 Percent [Member] Medium Term Notes 6.82 Percent [Member] Award Timing Disclosures [Line Items] Measurement Frequency [Domain] Measurement Frequency [Domain] SHAREHOLDERS’ EQUITY Equity [Text Block] DIVIDENDS Dividends Disclosure [Text Block] This text block may be used to disclose all or some of the information related to dividends declared, dividends paid, and the tax status of dividends as of the financial reporting date. NET INCOME ATTRIBUTABLE TO THE TRUST / PARTNERSHIP NET INCOME ATTRIBUTABLE TO THE TRUST / PARTNERSHIP Net Income (Loss) Attributable to Parent Gratiot Plaza Gratiot Plaza [Member] Gratiot Plaza [Member] Subsequent Event [Table] Subsequent Event [Table] Earnings Per Share Narrative [Line Items] Earnings Per Share Narrative [Line Items] Earnings Per Share Narrative [Line Items] Plaza Del Sol Plaza Del Sol [Member] Plaza Del Sol [Member] Net real estate Real Estate Investment Property, Net Gross amount at which carried at close of period, Total Balance at beginning of year Balance at end of year SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Gross Tyson's Station Tyson Station [Member] Tyson Station [Member] Courthouse Center Courthouse Center [Member] Courthouse Center [Member] Vesting Term Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period Share-Based Compensation Arrangement by Share-Based Payment Award, Award Vesting Period Preferred shares, authorized Preferred Stock, Shares Authorized Forward Contract Indexed to Issuer's Equity, Indexed Shares Forward Contract Indexed to Issuer's Equity, Indexed Shares Adoption Date Trading Arrangement Adoption Date Common unit, issued Common Unit, Issued Improvements SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Improvements Net increase in rental income Amortization of above and below Market Leases Hollywood Boulevard Hollywood Blvd [Member] Hollywood Blvd [Member] OPERATING INCOME Operating Income (Loss) Other property income Other property income Other property related income Acquisition of real estate Payments to Acquire Real Estate Name of Property [Axis] Name of Property Name of Property [Axis] Amortization of below market leases, lessee Amortization of Below Market Lease, Lessee Amortization of Below Market Lease, Lessee Exchangeable senior notes Exchangeable Senior Notes [Member] Exchangeable Senior Notes Year-end Fair Value of Equity Awards Granted in Covered Year that are Outstanding and Unvested Year-end Fair Value of Equity Awards Granted in Covered Year that are Outstanding and Unvested [Member] Campus Plaza Campus Plaza [Member] Campus Plaza Net income available for common shareholders, diluted Net income available for common shareholders, diluted Net income available for common shareholders, diluted Leases Revenue Recognition, Leases [Policy Text Block] Class of Stock [Axis] Class of Stock [Axis] Subsequent Event Type [Domain] Subsequent Event Type [Domain] Property Subject to or Available for Operating Lease [Line Items] Property, Plant, and Equipment, Lessor Asset under Operating Lease [Line Items] Aggregate Grant Date Fair Value of Equity Award Amounts Reported in Summary Compensation Table Aggregate Grant Date Fair Value of Equity Award Amounts Reported in Summary Compensation Table [Member] Second Mortgage on a retail shopping center in Rockville, MD Two Second Mortgage on a retail shopping center in Rockville, MD Two [Member] Second Mortgage on a retail shopping center in Rockville, MD Two Hoboken Hoboken [Member] Hoboken [Member] Statement [Table] Statement [Table] Purchase of capped calls Purchase of capped calls Purchase of capped calls Adjustments to reconcile net income to net cash provided by operating activities: Adjustment to Reconcile Net Income to Cash Provided by (Used in) Operating Activity [Abstract] FINANCING ACTIVITIES Cash Provided by (Used in) Financing Activity, Including Discontinued Operation [Abstract] Dividend equivalent rights Dividend equivalent rights Dividend equivalent rights Dividend equivalent rights DownREIT operating partnership units, outstanding Partners' Capital Account, Units 2025 Sold properties Sold properties [Member] Sold properties Proceeds from sale of real estate Proceeds from Real Estate and Real Estate Joint Ventures All Adjustments to Compensation All Adjustments to Compensation [Member] Amendment Flag Amendment Flag 29th Place 29th Place [Member] 29th Place [Member] Number of shares authorized Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Shares Authorized Crossroads Crossroads [Member] Crossroads [Member] Termination Date Trading Arrangement Termination Date Preferred units, outstanding Preferred Units, Outstanding Insider Trading Policies and Procedures Adopted Insider Trading Policies and Procedures Adopted [Flag] Number of interest rate swap agreements Number of Interest Rate Derivatives Held Equity method joint ventures Equity method joint ventures [Member] La Alameda & Assembly Row Hotel & Chandler & Escondido TIC Grove at Shrewsbury and Brook 35 Grove At Shrewsbury And Brook 35 [Member] GroveatShrewsbury & Brook 35 [Member] Weighted-average discount rate - operating leases Operating Lease, Weighted Average Discount Rate, Percent Summary of option activity Share-Based Payment Arrangement, Option, Activity [Table Text Block] Queen Anne Plaza Queen Anne Plaza [Member] Queen Anne Plaza [Member] Bristol Plaza Bristol [Member] Bristol [Member] Weighted average number of common shares Weighted average common shares outstanding—basic Weighted Average Number of Shares Outstanding, Basic Schedule of earnings per share Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Exercisable at the end of year (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Exercisable, Number Repairs and maintenance Cost of Property Repairs and Maintenance Subsequent Events [Abstract] Subsequent Events [Abstract] Acquired Lease Assets Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract] Debt Disclosure [Abstract] Debt Disclosure [Abstract] Scenario [Domain] Scenario [Domain] Interest Rate [Axis] Interest Rate [Axis] Interest Rate [Axis] Property Subject to or Available for Operating Lease, by Major Property Class [Table] Property, Plant, and Equipment, Lessor Asset under Operating Lease [Table] Net borrowings under revolving credit facility Proceeds from (Repayments of) Lines of Credit Forgone Recovery due to Expense of Enforcement, Amount Forgone Recovery due to Expense of Enforcement, Amount Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items] Common shares of beneficial interest, par value Common Stock, Par or Stated Value Per Share Consolidated Entities [Axis] Consolidated Entities [Axis] Common Units Common Units [Member] Common Units Summary of income tax status of dividends per share paid Schedule Of Income Tax Status Of Dividends Paid [Table Text Block] Schedule Of Income Tax Status Of Dividends Paid [Table Text Block] Nature Of Operations [Abstract] Nature Of Operations [Abstract] Nature Of Operations [Abstract] NET INCOME AVAILABLE FOR COMMON UNIT HOLDERS Net Income (Loss) Allocated to General Partners Use of Estimates Use of Estimates, Policy [Policy Text Block] Operating cash flows for finance leases Finance Lease, Interest Payment on Liability Huntington Square HuntingtonSquare [Member] Huntington Square [Member] Construction-in-progress (including $28,418 and $9,939 of consolidated variable interest entities, respectively) Construction in Progress, Gross 5.417% Series 1 Cumulative Convertible Preferred Shares, (stated at liquidation preference $25 per share), 392,878 shares issued and outstanding 5.417% Series 1 Cumulative Convertible Preferred Shares 5.417% Series 1 Cumulative Convertible Preferred [Member] Five point Four One Seven Percentage Series One Cumulative Convertible Preferred Stock [Member] Subsequent Event Subsequent Events [Text Block] Insider Trading Arrangements [Line Items] Less: Earnings allocated to unvested units Earnings allocated to unvested units Earnings allocated to unvested units Total liabilities Liabilities 2030 Finance Lease, Liability, to be Paid, Year Five Pike & Rose (one residential building) Pike & Rose (one residential building) [Member] Pike & Rose (one residential building) Pension Adjustments Prior Service Cost Pension Adjustments Prior Service Cost [Member] Material Terms of Trading Arrangement Material Terms of Trading Arrangement [Text Block] 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. Common shares issued, net Stock Issued During Period, Value, New Issues Unamortized debt issuance costs Unamortized Debt Issuance Expense Exchangeable Senior Notes [Table] Exchangeable Senior Notes [Table] Exchangeable Senior Notes Weighted average unvested units outstanding Incremental common units attributable to participating nonvested shares Incremental common units attributable to participating nonvested shares White Marsh Other White Marsh Other [Member] White Marsh Other [Member] Grossmont Center Grossmont Center [Member] Grossmont Center 401(K) and Deferred Compensation Plan Deferred Compensation Arrangement with Individual, by Type of Compensation, Pension and Other Postretirement Benefits [Member] Huntington Huntington [Member] Huntington [Member] Net income, excluding amount attributable to redeemable noncontrolling interests Net Income (Loss), Including Portion Attributable to Nonredeemable Noncontrolling Interest State of Organization Entity Incorporation, State or Country Code Non-NEOs Non-NEOs [Member] Interest Rate [Domain] Interest Rate [Domain] Interest Rate [Domain] Grove at Shrewsbury (East) Grove at Shrewsbury (East) [Member] Grove at Shrewsbury (East) [Member]