Commitments and Contingencies Disclosure [Abstract] Schedule of Real Estate Properties [Table] Schedule of Real Estate Properties [Table] Real Estate Property Ownership [Axis] Real Estate Property Ownership [Axis] Real Estate Properties [Domain] Real Estate Properties [Domain] Office Space [Member] Office Space [Member] Office space. Ground Leases [Member] Ground Leases [Member] Ground leases. Operating Leased Assets [Line Items] Operating Leased Assets [Line Items] Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract] Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract] 2015 Operating Leases, Future Minimum Payments Due, Next Twelve Months 2016 Operating Leases, Future Minimum Payments, Due in Two Years 2018 Operating Leases, Future Minimum Payments, Due in Three Years 2019 Operating Leases, Future Minimum Payments, Due in Four Years 2017 Operating Leases, Future Minimum Payments, Due in Five Years Thereafter Operating Leases, Future Minimum Payments, Due Thereafter Total Operating Leases, Future Minimum Payments Due Discontinued Operations and Disposal Groups [Abstract] Statement [Table] Statement [Table] Community [Axis] Community [Axis] Community [Axis] Community [Domain] Community [Domain] [Domain] for Community [Axis] Real Estate, Type of Property [Axis] Real Estate, Type of Property [Axis] Real Estate [Domain] Real Estate [Domain] Land Land [Member] Operating Community [Member] Operating Community [Member] Operating Community [Member] Statement [Line Items] Statement [Line Items] Gain/(loss) on sales of real estate owned, net of tax Gain (Loss) on Sale of Properties, Net of Applicable Income Taxes Gain/(loss) on sales of real estate owned, net of tax Gains (Losses) on Sales of Investment Real Estate Document Period End Date Document Period End Date Gain (Loss) on Disposition of Property Plant Equipment Gain (Loss) on Disposition of Property Plant Equipment Discontinued Operations (Textual) [Abstract] Discontinued Operations (Textual) [Abstract] Discontinued operations. Discontinued operations, number of communities sold Discontinued Operations, Communities Sold Discontinued Operations, Communities Sold Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax Proceeds from Sale of Property, Plant, and Equipment Proceeds from Sale of Property, Plant, and Equipment Number of communities sold Communities Sold Communities sold. Number of apartment homes sold Apartment Homes Sold Apartment homes sold. Real Estate Held-for-sale Real Estate Held-for-sale Summary of income from discontinued operations Summary of Income from Discontinued Operations [Abstract] Summary of income from discontinued operations. Rental income Disposal Group, Including Discontinued Operation, Rental Income Rental expenses Disposal Group Including Discontinued Operation Rental Expenses The aggregate total of rental expenses that is attributable to the disposal group. Property management fee Disposal Group Including Discontinued Operation Property Management Fee The aggregate total of property management fee expense that is attributable to the disposal group. Real estate depreciation Disposal Group Including Discontinued Operation Real Estate Depreciation The amount of expense recognized in the current period that reflects the allocation of the cost of tangible assets over the assets' useful lives that is attributable to the disposal group. Includes production and non-production related depreciation. Interest Disposal Group, Including Discontinued Operation, Interest Expense Income before net gain on the sale of property Disposal Group, Including Discontinued Operation, Operating Income (Loss) Impairment of Long-Lived Assets to be Disposed of Impairment of Long-Lived Assets to be Disposed of Income tax expense Discontinued Operation, Tax Effect of Discontinued Operation Income/(loss) from discontinued operations, net of tax Income (Loss) from Discontinued Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent Derivative Instruments and Hedging Activities Disclosure [Abstract] Derivative [Table] Derivative [Table] Legal Entity [Axis] Legal Entity [Axis] Entity [Domain] Entity [Domain] United Dominion Reality L.P. United Dominion Reality L P [Member] United Dominion Reality L. P. Energy [Axis] Energy [Axis] Energy [Domain] Energy [Domain] Derivative, by Nature [Axis] Derivative, by Nature [Axis] Derivative, Name [Domain] Derivative, Name [Domain] Position [Axis] Position [Axis] Position [Domain] Position [Domain] Derivative [Line Items] Derivative [Line Items] Derivative Liability Derivative Liability Derivative, Collateral, Right to Reclaim Securities Derivative, Collateral, Right to Reclaim Securities Derivative Liability, Fair Value, Amount Offset Against Collateral Derivative Liability, Fair Value, Amount Offset Against Collateral Derivative Liability Designated as Hedging Instrument, Fair Value Derivative Liability, Fair Value, Amount Not Offset Against Collateral Derivative Liability, Not Subject to Master Netting Arrangement Derivative Liability, Not Subject to Master Netting Arrangement Derivative, Collateral, Right to Reclaim Cash Derivative, Collateral, Right to Reclaim Cash Derivative Instruments, Gain (Loss) by Hedging Relationship, by Income Statement Location, by Derivative Instrument Risk [Table] Derivative Instruments, Gain (Loss) [Table] Derivative Instrument Risk [Axis] Derivative Instrument [Axis] Derivative Contract Type [Domain] Derivative Contract [Domain] Interest rate products Interest Rate Contract [Member] Income Statement Location [Axis] Income Statement Location [Axis] Income Statement Location [Domain] Income Statement Location [Domain] Other Income Expense [Member] Other Income Expense [Member] Other income (expense). Interest expense Interest Expense [Member] Derivative Instruments, Gain (Loss) by Hedging Relationship [Axis] Hedging Relationship [Axis] Hedging Relationship [Domain] Hedging Relationship [Domain] Cash Flow Hedging Cash Flow Hedging [Member] Derivative Instruments, Gain (Loss) [Line Items] Derivative Instruments, Gain (Loss) [Line Items] Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income, Effective Portion, Net, Total Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net, Total Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net Derivative Instruments, Gain (Loss) Recognized in Income, Net, Total Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing, Net Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing, Net Income Tax Disclosure [Abstract] Operating Loss Carryforwards [Table] Operating Loss Carryforwards [Table] UDR, Inc. UDR, Inc. [Member] UDR, Inc. [Member] Taxable REIT Subsidiaries Taxable REIT Subsidiaries [Member] Taxable REIT Subsidiaries [Member] Noncatastrophic Event [Axis] Noncatastrophic Event [Axis] Noncatastrophic Event [Domain] Noncatastrophic Event [Domain] Expiration Period [Axis] Expiration Period [Axis] Expiration Period [Axis] Expiration Period [Domain] Expiration Period [Domain] [Domain] for Expiration Period [Axis] 2020 through 2030 Expiration Period One [Member] Expiration Period One [Member] Income Tax Authority [Axis] Income Tax Authority [Axis] Income Tax Authority [Domain] Income Tax Authority [Domain] Internal Revenue Service (IRS) Internal Revenue Service (IRS) [Member] State State and Local Jurisdiction [Member] Operating Loss Carryforwards [Line Items] Operating Loss Carryforwards [Line Items] Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent Net loss carryforwards Operating Loss Carryforwards Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount Valuation allowance Deferred Tax Assets, Valuation Allowance Income Tax (benefit)/expense, Conversion of certain TRS entities to REITs Income Tax (benefit)/expense, Conversion of certain TRS entities to REITs Income Tax (benefit)/expense, Conversion of certain TRS entities to REITs Tax benefit/(provision), net Income Tax Expense (Benefit) Unrecognized Tax Benefits Unrecognized Tax Benefits Entities [Table] Entities [Table] Hedging Relationship [Axis] Interest rate contracts Range [Axis] Range [Axis] Range [Domain] Range [Domain] Maximum Maximum [Member] Entity Information [Line Items] Entity Information [Line Items] Derivative, Collateral, Obligation to Return Cash Derivative, Collateral, Obligation to Return Cash Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing, Net, Total Losses in the fair value of derivatives not designated in hedging relationships Fair value of derivatives in a net liability position Derivative, Net Liability Position, Aggregate Fair Value Payment required to pay for contract termination Assets Needed for Immediate Settlement, Aggregate Fair Value Statement of Financial Position [Abstract] Class of Stock [Axis] Class of Stock [Axis] Class of Stock [Domain] Class of Stock [Domain] 8.00% Series E Cumulative Convertible Preferred Stock Series E Preferred Stock [Member] Series F Preferred Stock [Member] Series F Preferred Stock [Member] Real estate owned: Real Estate Investment Property, Net [Abstract] Real estate under development, accumulated depreciation Real Estate Under Development Accumulated Depreciation Real estate under development, accumulated depreciation. Real estate held for disposition, accumulated depreciation Accumulated Depreciation of Real Estate Held for Sale Accumulated Depreciation of Real Estate Held for Sale Equity Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract] Preferred stock, par or state value per share Preferred Stock, Par or Stated Value Per Share Preferred stock, shares authorized Preferred Stock, Shares Authorized Preferred Stock, Shares Issued Preferred Stock, Shares Issued Preferred Stock, Shares Outstanding Preferred Stock, Shares Outstanding Common stock, par value Common Stock, Par or Stated Value Per Share Common stock, shares authorized Common Stock, Shares Authorized Common Stock, Shares, Issued Common Stock, Shares, Issued Common Stock, Shares, Outstanding Common Stock, Shares, Outstanding SEC Schedule III, Real Estate and Accumulated Depreciation Disclosure [Abstract] Real Estate and Accumulated Depreciation, by Property [Table] SEC Schedule III, Real Estate and Accumulated Depreciation, by Property [Table] Disposal Group Name [Axis] Disposal Group Name [Axis] Disposal Groups, Including Discontinued Operations, Name [Domain] Disposal Group Name [Domain] UDR Lighthouse DownREIT L.P. [Member] UDR Lighthouse DownREIT L.P. [Member] UDR Lighthouse DownREIT L.P. [Member] Investment Type [Axis] Investment Type [Axis] Investments [Domain] Investments [Domain] Corporate Joint Venture [Member] Corporate Joint Venture [Member] Geographical [Axis] Geographical [Axis] Segment, Geographical [Domain] Geographical [Domain] Western Region Western Region [Member] Western region. Mid Atlantic Region Mid Atlantic Region [Member] Mid-Atlantic region. Southeastern Region Southeastern Region [Member] Southeastern region. Northeast Region Northeast Region [Member] Northeast Region [Member] Southwestern Region Southwestern Region [Member] Southwestern region. Total Operating Properties [Member] Total Operating Properties [Member] Total Operating Properties [Member] Real Estate Under Development Real Estate Under Development [Member] Real estate under development. Commercial Held for Development Commercial Held for Development [Member] Commercial held for development. Name of Property [Axis] Name of Property [Axis] Name of Property [Domain] Name of Property [Domain] Harbor at Mesa Verde Harbor at Mesa Verde [Member] Harbor at Mesa Verde. 27 Seventy FIve Mesa Verde [Member] 27 Seventy FIve Mesa Verde [Member] 27 Seventy FIve Mesa Verde [Member] Pacific Shores Pacific Shores [Member] Pacific Shores. Huntington Vista Huntington Vista [Member] Huntington Vista. Missions at Back Bay Missions at Back Bay [Member] Missions at Back Bay. Coronado at Newport — North Coronado at Newport North [Member] Coronado at Newport North. Vista Del Rey Vista Del Rey [Member] Vista Del Rey. Coronado South Coronado South [Member] Coronado South. ORANGE COUNTY, CA ORANGE COUNTY, CA [Member] Orange County, CA. 2000 Post Street Two Thousand Post Street [Member] 2000 Post street. Birch Creek Birch Creek [Member] Birch Creek. Highlands Of Marin Highlands of Marin [Member] Highlands of Marin. Marina Playa Marina Playa [Member] Marina Playa. The Westerly The Westerly [Member] The Westerly [Member] River Terrace River Terrace [Member] River Terrace. CitySouth City South [Member] City South. Bay Terrace Bay Terrace [Member] Bay Terrace. Highlands of Marin Phase II Highlands of Marin Phase Second [Member] Highlands of Marin phase second. Edgewater Edgewater [Member] Edgewater. Almaden Lake Village Almaden Lake Village [Member] Almaden Lake village. SAN FRANCISCO, CA San Francisco, CA [Member] San Francisco CA. Rosebeach Rosebeach [Member] Rosebeach. Other Southern CA [Member] Other Southern CA [Member] Other Southern CA [Member] Tierra Del Rey Tierra Del Rey [Member] Tierra Del Rey. LOS ANGELES, CA Los Angeles CA [Member] Los Angeles CA. Crowne Pointe Crowne Pointe [Member] Crowne Pointe. Hilltop Hilltop [Member] Hilltop. The Kennedy Kennedy [Member] Kennedy. Hearthstone at Merrill Creek Hearthstone at Merrill Creek [Member] Hearthstone at Merrill Creek. Island Square Island Square [Member] Island square. SEATTLE, WA Seattle WA [Member] Seattle WA. Villas at Carlsbad Villas at Carlsbad [Member] Villas at Carlsbad. Boronda Manor Boronda Manor [Member] Boronda Manor. Garden Court Garden Court [Member] Garden Court. Cambridge Court Cambridge Court [Member] Cambridge Court. Laurel Tree Laurel Tree [Member] Laurel Tree. The Pointe At Harden Ranch Pointe at Harden Ranch [Member] The Pointe at Harden Ranch. The Pointe At Northridge Pointe at Northridge [Member] The Pointe at Northridge. The Pointe At Westlake Pointe at Westlake [Member] The Pointe at Westlake. MONTEREY PENINSULA, CA MONTEREY PENINSULA, CA [Member] Monterey Peninsula, CA. Verano at Rancho Cucamonga Town Square Verano at Rancho Cucamonga Town Square [Member] Verano at Rancho Cucamonga town square. Tualatin Heights Tualatin Heights [Member] Tualatin heights. Hunt Club Hunt Club [Member] Hunt club. PORTLAND, OR Portland OR [Member] Portland, OR. The Whitmore Whitmore [Member] The Whitmore. Ridgewood Ridgewood [Member] Ridgewood. Wellington Place at Olde Town Wellington Place at Olde Town [Member] Wellington Place at Olde Town. Andover House Andover House [Member] Andover House. Sullivan Place Sullivan Place [Member] Sullivan Place. Courts at Huntington Station [Member] Courts at Huntington Station [Member] Courts at Huntington Station [Member] Circle Towers Circle Towers [Member] Circle towers. Delancey at Shirlington Delancey at Shirlington [Member] Delancey at Shirlington. METROPOLITAN DC Metropolitan DC [Member] Metropolitan D.C. Calvert’s Walk Calvert's Walk [Member] Calvert's Walk. 20 Lambourne Twenty Lambourne [Member] 20 Lambourne. BALTIMORE, MD Baltimore MD [Member] Baltimore, MD. New York Properties [Member] New York Properties [Member] New York Properties [Member] Inlet Bay Inlet Bay [Member] Inlet Bay. MacAlpine Place Mac Alpine Place [Member] MacAlpine place. TAMPA, FL Tampa Fl [Member] Tampa, Fl. Legacy Hill Legacy Hill [Member] Legacy hill. Hickory Run Hickory Run [Member] Hickory Run. Carrington Hills Carrington Hills [Member] Carrington hills. Brookridge Brookridge [Member] Brookridge. Breckenridge Breckenridge [Member] Breckenridge. Polo Park Polo Park [Member] Polo Park. NASHVILLE, TN Nashville TN [Member] Nashville, TN. The Reserve and Park at Riverbridge Reserve and Park at Riverbridge [Member] The Reserve and Park at Riverbridge. OTHER FLORIDA Other Florida [Member] Other Florida. Inwood West Inwood West [Member] Inwood West. 14 North North [Member] 14 North. BOSTON, MA Boston, MA [Member] Boston, MA. 10 Hanover Square Hanover Square [Member] 10 Hanover Square. 95 Wall Street Ninety Five Wall [Member] 95 Wall. NEW YORK, NY New York NY [Member] New York NY. THIRTY377 Thirty Three Seven Seven [Member] THIRTY377. Legacy Village Legacy Village [Member] Legacy village. DALLAS, TX Dallas TX [Member] Dallas, TX. Barton Creek Landing Barton Creek Landing [Member] Barton Creek landing. AUSTIN, TX Austin TX [Member] Austin, TX. Office Building [Member] Circle Tower Office Building [Member] Circle Tower Office Building [Member] DelRey Tower [Member] DelRey Tower [Member] DelRey Tower [Member] Other Other Corporate [Member] Other corporate. TOTAL CORPORATE Corporate Segment [Member] TOTAL COMMERCIAL & CORPORATE Commercial and Corporate [Member] Commercial and corporate. Total Real Estate Owned Real Estate Owned [Member] Real estate owned. Estimated Depreciable Lives of Buildings Range [Axis] Estimated Depreciable Lives of Buildings Range [Axis] Estimated Depreciable Lives of Buildings Range [Axis] Estimated Depreciable Lives of Buildings Years [Domain] Estimated Depreciable Lives of Buildings Range [Domain] [Domain] for Estimated Depreciable Lives of Buildings Range Estimated depreciable lives of buildings range beginning Estimated Depreciable Lives of Buidlings Range Beginning [Member] Estimated Depreciable Lives of Buidlings Range Beginning [Member] Estimated depreciable lives of buildings range end Estimated Depreciable Lives of Buildings Range End [Member] Estimated Depreciable Lives of Buildings Range End [Member] Real Estate and Accumulated Depreciation [Line Items] SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items] Deferred Finance Costs, Net Deferred Finance Costs, Net Encumbrances SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances Initial Costs, Land and Land Improvements SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land Initial Costs, Buildings and Improvements SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements Total Initial Acquisition Costs Real Estate and Accumulated Depreciation, Initial Cost of Land and Buildings and Improvements Real estate and accumulated depreciation initial cost of land and buildings and improvements. Costs of Improvements Capitalized Subsequent to Acquisition Costs SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Improvements Gross Amount at Which Carried at Close of Period, Land and Land Improvements SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land Gross Amount at Which Carried at Close of Period, Buildings & Buildings Improvements SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements Total Carrying Value SEC Schedule III, Real Estate, Gross Accumulated Depreciation SEC Schedule III, Real Estate Accumulated Depreciation Aggregate cost for federal income tax purposes SEC Schedule III, Real Estate, Federal Income Tax Basis Depreciable life for all buildings SEC Schedule III, Real Estate and Accumulated Depreciation, Life Used for Depreciation Real Estate Owned, Gross [Roll Forward] SEC Schedule III, Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward] Balance at beginning of the year Real estate acquired SEC Schedule III, Real Estate, Other Acquisitions Capital expenditures and development SEC Schedule III, Real Estate, Improvements Real estate sold SEC Schedule III, Real Estate, Cost of Real Estate Sold Retirement of fully depreciated assets SEC Schedule III, Real Estate, Other Deductions Real Estate Investment Property, at Cost Real Estate Investment Property, at Cost Hurricane related impairment of assets Real Estate, Impairment, Amount Gross Real Estate, Impairment, Amount Gross Balance at end of the year Real Estate Owned, Accumulated Depreciation [Roll Forward] SEC Schedule III, Reconciliation of Real Estate Accumulated Depreciation [Roll Forward] Balance at beginning of the year Depreciation expense for the year SEC Schedule III, Real Estate Accumulated Depreciation, Depreciation Expense Accumulated depreciation on sales SEC Schedule III, Real Estate Accumulated Depreciation, Real Estate Sold Accumulated depreciation on retirements of fully depreciated asset SEC Schedule III, Real Estate Accumulated Depreciation, Other Deductions Real Estate Owned, Accumulated Depreciation Real Estate Owned, Accumulated Depreciation Write off of accumulated depreciation on hurricane related impaired assets Real Estate, Impairment, Amount Accumulated Depreciation Real Estate, Impairment, Amount Accumulated Depreciation Balance at end of year Debt Disclosure [Abstract] Schedule of Long-term Debt Instruments [Table] Schedule of Long-term Debt Instruments [Table] Liability Class [Axis] Liability Class [Axis] Fair Value by Liability Class [Domain] Fair Value by Liability Class [Domain] Secured Debt [Member] Secured Debt [Member] Debt Instrument [Axis] Debt Instrument [Axis] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Fixed Rate Debt Fixed Rate Debt [Member] Fixed Rate Debt. Variable Rate Debt Variable Rate Debt [Member] Variable Rate Debt. Long-term Debt, Type [Axis] Long-term Debt, Type [Axis] Long-term Debt, Type [Domain] Long-term Debt, Type [Domain] Mortgages [Member] Mortgages [Member] Tax-exempt secured notes payable Tax Exempt Notes Payable [Member] Tax Exempt Notes Payable. Fannie Mae credit facilities Line of Credit [Member] Debt Instrument [Line Items] Debt Instrument [Line Items] Principal outstanding Secured Debt Including Debt on Real Estate Held for Sale Secured debt including debt on real estate held for sale. Weighted Average Interest Rate Debt Instrument, Interest Rate During Period Weighted Average Years to Maturity Debt Instrument Weighted Average Years to Maturity Debt instrument weighted average years to maturity. Number of Communities Encumbered Number of Communities Encumbered Number of Communities Encumbered. Deferred Finance Costs, Net Equity Method Investments and Joint Ventures [Abstract] Schedule of Equity Method Investments [Table] Schedule of Equity Method Investments [Table] Ownership Percentage [Axis] Ownership Percentage [Axis] Ownership Percentage [Axis] Ownership Percentage [Domain] Ownership Percentage [Domain] [Domain] for Ownership Percentage [Axis] Subsequent Investment [Member] Subsequent Investment [Member] Subsequent Investment [Member] Initial Investment [Member] Initial Investment [Member] Initial Investment [Member] Receivable Type [Axis] Receivable Type [Axis] Receivable Type [Domain] Receivable [Domain] Participating Loan Investment Steele Creek Denver Colorado [Member] Participating Loan Investment Steele Creek Denver Colorado [Member] Participating Loan Investment Steele Creek Denver Colorado [Member] Unconsolidated Joint Venture Vitruvian Park [Member] Unconsolidated Joint Venture Vitruvian Park [Member] Unconsolidated Joint Venture Vitruvian Park [Member] Other Ownership Interests Name [Axis] Other Ownership Interests Name [Axis] Other Ownership Interests, Name [Domain] Other Ownership Interests, Name [Domain] Development Community [Member] Development Community [Member] Development Community [Member] Investment, Name [Axis] Investment, Name [Axis] Equity Method Investee, Name [Domain] Investment, Name [Domain] Ashton Dublin Land [Member] Ashton Dublin Land [Member] Ashton Dublin Land [Member] 717 Olympic [Member] 717 Olympic [Member] 717 Olympic [Member] Cirque [Member] Cirque [Member] Cirque [Member] Unconsolidated Joint Venture Other MetLife [Member] Unconsolidated Joint Venture Other MetLife [Member] Unconsolidated Joint Venture Other MetLife [Member] MetLife I Unconsolidated Joint Venture One U D R Met Life Partnership [Member] Unconsolidated joint venture one UDR MetLife partnership. Unconsolidated Joint Venture 399 Fremont [Member] Unconsolidated Joint Venture 399 Fremont [Member] Unconsolidated Joint Venture 399 Fremont [Member] MetLife II Unconsolidated Joint Venture Seven UDR MetLife II Partnership [Member] Unconsolidated Joint Venture Seven UDR MetLife II Partnership [Member] KFH Unconsolidated Joint Venture Three [Member] Unconsolidated Joint Venture Three. Texas JV Unconsolidated Joint Venture Four Texas [Member] Unconsolidated joint venture four Texas. Domain College Park [Member] Domain College Park [Member] Domain College Park [Member] Preferred Equity Investment West Coast Development JV [Member] Preferred Equity Investment West Coast Development JV [Member] Preferred Equity Investment West Coast Development JV [Member] Cadillac Land [Member] Cadillac Land [Member] Cadillac Land [Member] Hollywood Land [Member] Hollywood Land [Member] Hollywood Land [Member] Wilshire LaJolla [Member] Wilshire LaJolla [Member] Wilshire LaJolla [Member] CityLine [Member] CityLine [Member] CityLine [Member] Equity Investment Exchanged [Axis] Equity Investment Exchanged [Axis] Equity Investment Exchanged Assets Exchanged, Type [Domain] Assets Exchanged, Type [Domain] Assets Exchanged, Type Property, Plant and Equipment, Type [Axis] Property, Plant and Equipment, Type [Axis] Property, Plant and Equipment, Type [Domain] Property, Plant and Equipment, Type [Domain] Buildings Buildings [Member] Buildings. Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets, Major Class Name [Domain] Finite-Lived Intangible Assets, Major Class Name [Domain] Business Acquisition [Axis] Business Acquisition [Axis] Business Acquisition, Acquiree [Domain] Business Acquisition, Acquiree [Domain] Consolidated Joint Venture [Axis] Consolidated Joint Venture [Axis] Consolidated Joint Venture [Axis] Consolidated Joint Venture [Domain] Consolidated Joint Venture [Domain] [Domain] for Consolidated Joint Venture [Axis] Pier 4 Pier 4 [Member] Pier 4 [Member] Partial Payments [Axis] Partial Payments [Axis] Partial Payments [Axis] Partial Payments [Domain] Partial Payments [Domain] [Domain] for Partial Payments [Axis] Subsequent Event Type [Axis] Subsequent Event Type [Axis] Subsequent Event Type [Domain] Subsequent Event Type [Domain] Subsequent Event [Member] Subsequent Event [Member] Schedule of Equity Method Investments [Line Items] Schedule of Equity Method Investments [Line Items] Casualty-related (recoveries)/charges, net Casualty (Recoveries)/Charges Casualty (Recoveries)/Charges Number of apartments of development community Number of apartments of development community Number of apartments of development community Joint Ventures Joint Ventures [Abstract] Joint Ventures. Real Estate Investment Property, Net Real Estate Investment Property, Net Joint venture, number of homes in communities Joint Venture Number of Apartment Homes in Operating Communities Joint venture number of apartment homes in operating communities. Property, Plant and Equipment, Additions Property, Plant and Equipment, Additions Number of Units in Real Estate Property Number of Units in Real Estate Property Line of Credit Facility, Maximum Borrowing Capacity Line of Credit Facility, Maximum Borrowing Capacity Weighted average interest rate at the end of the period Line of Credit Facility, Interest Rate at Period End Equity method investment, ownership percent Equity Method Investment, Ownership Percentage Payments to Acquire Interest in Subsidiaries and Affiliates Payments to Acquire Interest in Subsidiaries and Affiliates Unamortized discount Debt Instrument, Unamortized Discount First installment of payable incurred in partial consideration for acquisition of ownership interest in joint venture Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months Second installment of payable incurred in partial consideration for acquisition of ownership interest in joint venture Long-term Debt, Maturities, Repayments of Principal in Year Two Interest expense incurred during period Interest Expense Investment in and advances to unconsolidated joint ventures, net Equity Method Investments Income from Participating Loan Income from Participating Loan Income from Participating Loan Deferred gains on the sale of depreciable property Deferred Gain on Sale of Property Communities Sold Management fees for our involvement in the joint ventures Management Fees Revenue Number of Communities to be Acquired Number of Communities to be Acquired Number of Communities to be Acquired Number of Completed Communities Number of Completed Communities Number of Completed Communities Condition for Community considered to have stabilized occupancy Condition for Community considered to have stabilized occupancy Condition for Community considered to have stabilized occupancy. Real Estate Owned Gross Real Estate Owned Gross Real Estate Owned Gross. Secured debt, net Secured Debt SEC Schedule III, Real Estate, Cost of Real Estate Sold Number of Real Estate Properties Number of Real Estate Properties Number of extension options on loan Number of extension options on loan Number of extension options on loan Extension period of option on loan Extension period of option on loan Extension period of option on loan Number of markets operating within Number of Markets Operating Within Number of Markets Operating Within Community Threshold, Percent Occupancy Threshold Community Threshold, Percent Occupancy Threshold Community Threshold, Percent Occupancy Threshold Community Threshold, Period Above Occupancy Threshold Community Threshold, Period Above Occupancy Threshold Community Threshold, Period Above Occupancy Threshold Participating Loan, Interest Rate, Stated Percentage Participating Loan, Interest Rate, Stated Percentage Participating Loan, Interest Rate, Stated Percentage Hold Period Hold Period Hold Period Equity Method Investment, Transaction Expenses Equity Method Investment, Transaction Expenses Equity Method Investment, Transaction Expenses Casualty-related charges/(recoveries), net Casualty-Related (Recoveries)/Charges, net Casualty-Related (Recoveries)/Charges, net Apartment Homes Sold Number of Communities Acquired Number of Communities Acquired Number of Communities Acquired Number of apartment homes acquired Number of Apartment Homes Acquired Number of apartment homes acquired. Noncash or Part Noncash Acquisition, Debt Assumed Noncash or Part Noncash Acquisition, Debt Assumed Debt, Weighted Average Interest Rate Debt, Weighted Average Interest Rate ASSETS Assets [Abstract] Real estate held for investment Less: accumulated depreciation Real Estate Investment Property, Accumulated Depreciation Real estate held for investment net Real Estate held for Investment Net excluding real estate under development or held for disposition Real Estate held for Investment Net excluding real estate under development or held for disposition Real estate under development (net of accumulated depreciation of $0 and $0, respectively) Development in Process Real estate held for disposition (net of accumulated depreciation of $553 and $830, respectively) Real Estate Held For Sale, Net of Depreciation Real Estate Held For Sale, Net of Depreciation Total real estate owned, net of accumulated depreciation Real Estate, Net The net book value of real estate held for investment and real estate under development. Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Restricted Cash Restricted Cash and Cash Equivalents Notes receivable, net Financing Receivable, Net Investment in and advances to unconsolidated joint ventures, net Investments in Affiliates, Subsidiaries, Associates, and Joint Ventures, Fair Value Disclosure Other assets Other Assets Total assets Assets LIABILITIES AND EQUITY Liabilities and Equity [Abstract] Liabilities: Liabilities [Abstract] Unsecured debt, net Unsecured Debt Real estate taxes payable Accrual for Taxes Other than Income Taxes Accrued interest payable Interest Payable Security deposits and prepaid rent Advance Rent Distributions payable Dividends Payable Accounts payable, accrued expenses, and other liabilities Accounts Payable and Accrued Liabilities Total liabilities Liabilities Redeemable non-controlling interests in the Operating Partnership and DownREIT Partnership Redeemable Noncontrolling Interest, Equity, Common, Carrying Amount Preferred stock, no par value; 50,000,000 shares authorized Preferred Stock, Value, Issued Common stock, $0.01 par value; 350,000,000 shares authorized 267,259,469 and 261,844,521 shares issued and outstanding at December 31, 2016 and 2015, respectively Common Stock, Value, Issued Additional paid-in capital Additional Paid in Capital Distributions in excess of net income Accumulated Distributions in Excess of Net Income Accumulated other comprehensive income/(loss), net Accumulated Other Comprehensive Income (Loss), Net of Tax Total stockholders' equity Stockholders' Equity Attributable to Parent Non-controlling interest Stockholders' Equity Attributable to Noncontrolling Interest Total equity Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest Total liabilities and equity Liabilities and Equity Hedging Designation [Axis] Hedging Designation [Axis] Hedging Designation [Domain] Hedging Designation [Domain] Designated as Hedging Instrument Designated as Hedging Instrument [Member] Not Designated as Hedging Instrument Not Designated as Hedging Instrument [Member] Interest rate swaps Interest Rate Swap [Member] Interest rate caps Interest Rate Cap [Member] Interest Rate Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months, Net Interest Rate Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months, Net Number of Instruments Number of Interest Rate Derivatives Held Derivative, Notional Amount Derivative, Notional Amount Outstanding interest rate derivatives designated as hedging instruments Interest Rate Cash Flow Hedges [Abstract] Outstanding interest rate derivatives not designated as hedging instrument Interest Rate Derivative Instruments Not Designated as Hedging Instruments [Abstract] Guarantor Obligations, Nature [Axis] Guarantor Obligations, Nature [Axis] Guarantor Obligations, Nature [Domain] Guarantor Obligations, Nature [Domain] Financial Guarantee Financial Guarantee [Member] Measurement Frequency [Axis] Measurement Frequency [Axis] Fair Value, Measurement Frequency [Domain] Fair Value, Measurement Frequency [Domain] Fair Value, Measurements, Recurring [Member] Fair Value, Measurements, Recurring [Member] Asset Class [Axis] Asset Class [Axis] Asset Class [Domain] Asset Class [Domain] Line of Credit [Member] Mortgages [Member] Measurement Basis [Axis] Measurement Basis [Axis] Fair Value Measurement [Domain] Fair Value Measurement [Domain] Portion at Fair Value Measurement [Member] Portion at Fair Value Measurement [Member] Reported Value Measurement [Member] Reported Value Measurement [Member] Range of inital term of debt [Axis] Range of inital term of debt [Axis] Range of inital term of debt [Axis] Range of inital term of debt [Domain] Range of inital term of debt [Domain] [Domain] for Range of inital term of debt [Axis] Refinanced credit facilities [Axis] Refinanced credit facilities [Axis] Refinanced credit facilities [Axis] Refinanced credit facilities [Domain] Refinanced credit facilities [Domain] [Domain] for Refinanced credit facilities [Axis] Lender Name [Axis] Lender Name [Axis] Line of Credit Facility, Lender [Domain] Line of Credit Facility, Lender [Domain] UDR Bank Credit Facility UDR Bank Credit Facility [Member] UDR Bank Credit Facility. Unsecured Working Capital Credit Facility due January 2019 [Member] Unsecured Working Capital Credit Facility due January 2019 [Member] Unsecured Working Capital Credit Facility due January 2019 [Member] 3.75 MTN Due July 2024 [Member] 3.75 MTN Due July 2024 [Member] 3.75 MTN Due July 2024 [Member] Debt Assumed As Part of Acquisition [Member] Debt Assumed As Part of Acquisition [Member] Debt Assumed As Part of Acquisition [Member] Tax-exempt secured notes payable Tax Exempt Secured Notes Payable [Member] Tax-exempt secured notes payable. Unsecured Revolving Credit Facility due October 2015 Unsecured Revolving Credit Facility due October Two Thousand Fifteen [Member] Unsecured Revolving Credit Facility due October 2015 4.63% Medium-Term Notes due January 2022 Four Point Six Three Percent Term Medium Notes Due January Two Thousand Twenty-Two [Member] Four Point Six Three Percent Term Medium Notes Due January Two Thousand Twenty-Two [Member] ThreePointSevenTermNotesDueOctober2020 [Member] ThreePointSevenTermNotesDueOctober2020 [Member] ThreePointSevenTermNotesDueOctober2020 [Member] Fannie Mae Fannie Mae [Member] Fannie Mae. Unsecured Debt [Member] Unsecured Debt [Member] Revolving Credit Facility [Member] Revolving Credit Facility [Member] 4.00% MTN Due October 2025 [Member] 4.00% MTN Due October 2025 [Member] 4.00% MTN Due October 2025 [Member] 2.95% Medium-Term Note due September 2026 [Member] 2.95% Medium-Term Note due September 2026 [Member] 2.95% Medium-Term Note due September 2026 [Member] Five Point Two Five Percent, Medium Term Notes, Due January 2016 [Member] Five Point Two Five Percent, Medium Term Notes, Due January 2016 [Member] 5.25% Medium-Term Notes due January 2016. 6.21 Medium Term Note, Due January 2016 [Member] 6.21 Medium Term Note, Due January 2016 [Member] 6.21 Medium Term Note, Due January 2016 [Member] Fixed Rate Mortgage Due November 2026 [Member] Fixed Rate Mortgage Due November 2026 [Member] Fixed Rate Mortgage Due November 2026 [Member] Fixed Rate Mortgage Due June 2026 [Member] Fixed Rate Mortgage Due June 2026 [Member] Fixed Rate Mortgage Due June 2026 [Member] Commercial Paper [Member] Commercial Paper [Member] Amortization of Financing Costs Amortization of Financing Costs Long-term Commercial Paper Long-term Commercial Paper Secured Debt (Textual) [Abstract] Secured Debt (Textual) [Abstract] Secured debt. Secured debt amount which encumbers real estate owned based upon book value Secured Debt, Encumbers Real Estate Owned, Amount Secured Debt, Encumbers Real Estate Owned, Amount. Percentage of secured debt which encumbers real estate owned based upon book value Secured Debt, Encumbers Real Estate Owned, Percent Secured Debt, Encumbers Real Estate Owned, Percent. Secured debt amount of real estate owned which is unencumbered Secured Debt, Unencumbered Real Estate Owned, Amount Secured Debt, Unencumbered Real Estate Owned, Amount. Percentage of secured debt of real estate owned which is unencumbered Secured Debt, Unencumbered Real Estate Owned, Percent Secured Debt, Unencumbered Real Estate Owned, Percent. Debt instrument, maturity date range, start Debt Instrument, Maturity Date Range, Start Debt instrument, maturity date range, end Debt Instrument, Maturity Date Range, End Notes payable minimum interest rates range Debt Instrument, Interest Rate, Effective Percentage Rate Range, Minimum Notes payable maximum interest rates range Debt Instrument, Interest Rate, Effective Percentage Rate Range, Maximum Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Long-term Debt Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Long-term Debt Liabilities, Fair Value Adjustment Liabilities, Fair Value Adjustment Amortization of Debt Discount (Premium) Amortization of Debt Discount (Premium) Unamortized fair market adjustment Credit facilities with aggregate commitment Portion of Medium Term Note subject to Interest Rate Swaps Portion of Medium Term Note subject to Interest Rate Swaps Portion of Medium Term Note subject to Interest Rate Swaps Secured Debt Including Debt on Real Estate Held for Sale Long-term Line of Credit Long-term Line of Credit Interest rate at the end of the period Interest rate at the end of the period Debt Instrument, Interest Rate, Effective Percentage Debt Instrument, Maturity Date Debt Instrument, Maturity Date Percentage of Debt Instrument Price Percentage of Debt Instrument Price Percentage of Debt Instrument Price Line of Credit Facility, Interest Rate Description Line of Credit Facility, Interest Rate Description Line of Credit Facility, Commitment Fee Description Line of Credit Facility, Commitment Fee Description Long-term Debt, Weighted Average Interest Rate Long-term Debt, Weighted Average Interest Rate Senior Notes Senior Notes Guarantor borrowing capacity Guarantor Obligations, Maximum Exposure, Undiscounted Line of Credit Facility, Description Range Low Line of Credit Facility, Description Range Low Line of Credit Facility, Description Range Low Line of Credit Facility, Description Range High Line of Credit Facility, Description Range High Line of Credit Facility, Description Range High Line of Credit Facility, Commitment Fee Description Range Low Line of Credit Facility, Commitment Fee Description Range Low Line of Credit Facility, Commitment Fee Description Range Low Line of Credit Facility, Commitment Fee Description Range High Line of Credit Facility, Commitment Fee Description Range High Line of Credit Facility, Commitment Fee Description Range High Commercial Paper, at Carrying Value Commercial Paper, at Carrying Value Property, Plant and Equipment [Abstract] Business Acquisition, Pro Forma Information, Nonrecurring Adjustments [Table] Business Acquisition, Pro Forma Information, Nonrecurring Adjustments [Table] Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items] Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items] Schedule of taxable distributions paid per common share Tax Treatment of Distributions [Table Text Block] This table represents the tax treatments of distribution paid to unit/shareholders. Ordinary dividends are taxed as ordinary income while qualified dividends are taxed as capital gains. This table also includes the nontaxable portions (deferred until unit/share sold) as long-term/short-term capital gains/losses. Schedule of components of the provision for income taxes Schedule of Components of Income Tax Expense (Benefit) [Table Text Block] Schedule of components of TRS deferred tax assets and liabilities Schedule of Deferred Tax Assets and Liabilities [Table Text Block] Schedule of effective income tax rate reconciliation Schedule of Effective Income Tax Rate Reconciliation [Table Text Block] Noncontrolling Interest [Abstract] Redeemable noncontrolling interests in the Operating Partnership Redeemable Noncontrolling Interest [Table Text Block] Investment, Name [Axis] Investment, Name [Domain] Summary of investments in unconsolidated joint ventures Equity Method Investments [Table Text Block] Summarized Income Statement Relating to Unconsolidated Joint Ventures [Table Text Block] Summarized Income Statement Relating to Unconsolidated Joint Ventures [Table Text Block] [Table Text Block] for Summarized Income Statement Relating to Unconsolidated Joint Ventures [Table] Accounting Policies [Abstract] Recent Accounting Pronouncements New Accounting Pronouncements, Policy [Policy Text Block] Real estate Property, Plant and Equipment, Policy [Policy Text Block] Cash and cash equivalents Cash and Cash Equivalents, Policy [Policy Text Block] Restricted cash Cash and Cash Equivalents, Restricted Cash and Cash Equivalents, Policy [Policy Text Block] Derivative financial instruments Derivatives, Policy [Policy Text Block] Non-controlling interests Consolidation, Policy [Policy Text Block] Revenue and real estate sales gain recognition Revenue Recognition, Real Estate Transactions, Policy [Policy Text Block] Discontinued operations Discontinued Operations, Policy [Policy Text Block] Allocation of General and Administrative Expenses Selling, General and Administrative Expenses, Policy [Policy Text Block] Income taxes Income Tax, Policy [Policy Text Block] Advertising costs Advertising Cost, Policy, Expensed Advertising Cost [Policy Text Block] Comprehensive income Comprehensive Income, Policy [Policy Text Block] Use of estimates Use of Estimates, Policy [Policy Text Block] Market concentration risk Market Concentration Risk [Policy Text Block] Market concentration risk. INCOME TAXES Income Tax Disclosure [Text Block] Document and Entity Information [Abstract] Document and Entity Information. Entity Registrant Name Entity Registrant Name Entity Central Index Key Entity Central Index Key Document Type Document Type Amendment Flag Amendment Flag Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Current Fiscal Year End Date Current Fiscal Year End Date Entity Well-known Seasoned Issuer Entity Well-known Seasoned Issuer Entity Voluntary Filers Entity Voluntary Filers Entity Current Reporting Status Entity Current Reporting Status Entity Filer Category Entity Filer Category Entity Public Float Entity Public Float Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Fair Values Derivatives, Balance Sheet Location, by Derivative Contract Type [Table] Fair Values Derivatives, Balance Sheet Location, by Derivative Contract Type [Table] Balance Sheet Location [Axis] Balance Sheet Location [Axis] Balance Sheet Location [Domain] Balance Sheet Location [Domain] Other assets Other Assets [Member] Other liabilities Other Liabilities [Member] Derivatives, Fair Value [Line Items] Derivatives, Fair Value [Line Items] Fair value of Company's derivative financial instruments and their classification on Consolidated Balance Sheet Derivative Assets (Liabilities), at Fair Value, Net, by Balance Sheet Classification [Abstract] Derivative Asset Designated as Hedging Instrument, Fair Value Derivative Asset, Fair Value, Amount Not Offset Against Collateral Derivative Asset Not Designated as Hedging Instrument, Fair Value Derivative Instruments Not Designated as Hedging Instruments, Asset, at Fair Value Derivative Liability Not Designated as Hedging Instrument, Fair Value Derivative Instruments Not Designated as Hedging Instruments, Liability, at Fair Value Earnings Per Share [Abstract] Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block] Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block] Secured debt instruments Schedule of Long-term Debt Instruments [Table Text Block] Secured credit facilities Schedule of Line of Credit Facilities [Table Text Block] Summary of short-term bank borrowings under bank credit facility Summary of Short Term Bank Borrowings Under Bank Credit Facility [Table Text Block] Tabular disclosure of short-term contractual arrangements with lenders, including letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of draw downs on the line. Working capital credit facility Short-term Debt [Text Block] Aggregate maturities of secured debt Schedule of Maturities of Long-term Debt [Table Text Block] Real Estate [Abstract] Schedule of Property, Plant and Equipment [Table] Property, Plant and Equipment [Table] Equity Components [Axis] Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] UDR DownREIT Unit [Member] UDR DownREIT Unit [Member] UDR DownREIT Unit [Member] Related Party [Axis] Related Party [Axis] Related Party [Domain] Related Party [Domain] Partner Type [Axis] Partner Type [Axis] Partner Type of Partners' Capital Account, Name [Domain] Partner Type of Partners' Capital Account, Name [Domain] Home Acquisition [Member] Home Acquisition [Member] Home Acquisition [Member] Construction in progress Construction in Progress [Member] Building and improvements Building and Building Improvements [Member] Property, Plant and Equipment [Line Items] Property, Plant and Equipment [Line Items] Land Land Summary of carrying amounts for real estate owned (at cost) Summary of Carrying Amounts for Real Estate Owned [Abstract] Summary Of Carrying Amounts For Real Estate Owned. Land Improvements Land Improvements Investment Building and Building Improvements, and Furniture, Fixtures and Equipment Investment Building and Building Improvements, and Furniture, Fixtures and Equipment Investment Building and Building Improvements, and Furniture, Fixtures and Equipment Depreciable property - held and used: Depreciable Property Held and Used [Abstract] Depreciable property - held and used. Under development: Real Estate Under Development [Abstract] Real Estate Under Development. Sold or held for sale: Property, Plant and Equipment Assets Held-for-sale Disclosure [Abstract] Sold or held for sale Real estate owned Real Estates Owned Accumulated Depreciation Real Estates Owned Accumulated Depreciation Accumulated depreciation for real estate owned, including real estate held for investment, real estate under development, and real estate held for disposition. Accumulated depreciation Notes Receivable Policy Loans Receivable, Policy [Policy Text Block] Investment in joint ventures Equity Method Investments, Policy [Policy Text Block] Redeemable noncontrolling interests in the Operating Partnership Redeemable Non Controlling Interests in Operating Partnership [Policy Text Block] Disclosure of an entity's accounting policy for redeemable noncontrolling interests, which is reflected in the mezzanine section of the consolidated balance sheet. Income Taxes Stock-based employee compensation plans Share-based Compensation, Option and Incentive Plans Policy [Policy Text Block] Cost of raising capital Cost of Raising Capital [Policy Text Block] Disclosure of entity's accounting treatment for costs incurred in issuances of equity and debt, including deferred financing costs. Real Estate Held for Disposition [Member] Real Estate Held for Disposition [Member] Real Estate Held for Disposition [Member] Foxborough Foxborough [Member] Foxborough. 1818 Platinum Triangle One Thousand Eight Hundred Eighteen Platinum Triangle [Member] One Thousand Eight Hundred eighteen Platinum Triangle. Beach & Ocean [Member] Beach & Ocean [Member] Beach & Ocean [Member] 388 Beale Three Hundred Eighty Eight Beale [Member] Three hundred eighty eight Beale. Channel @ Mission Bay [Member] Channel @ Mission Bay [Member] Channel @ Mission Bay [Member] Jefferson at Marina del Rey Jefferson at Marina Del Rey [Member] Jefferson at Marina del Rey. The Hawthorne Hawthorne [Member] Hawthorne. Borgata Borgata [Member] Borgata. elements too Elements Too [Member] Elements Too. 989elements Nine Hundred Eighty Nine Elements [Member] Nine hundred eighty nine elements. Lightbox [Member] Lightbox [Member] Lightbox [Member] Waterscape [Member] Waterscape [Member] Waterscape [Member] Ashton Bellevue [Member] Ashton Bellevue [Member] Ashton Bellevue [Member] TEN20 [Member] TEN20 [Member] TEN20 [Member] Milehouse [Member] Milehouse [Member] Milehouse [Member] Windemere at Sycamore Highland Windemere at Sycamore Highland [Member] Windemere at Sycamore Highland. Dominion Middle Ridge Dominion Middle Ridge [Member] Dominion Middle Ridge. Dominion Lake Ridge Dominion Lake Ridge [Member] Dominion Lake Ridge. Presidential Greens Presidential Greens [Member] Presidential Greens. Waterside Towers Waterside Towers [Member] Waterside towers. View 14 View Fourteen [Member] View fourteen. Signal Hill Signal Hill [Member] Signal Hill. Domain Brewers Hill Domain Brewers Hill [Member] Domain Brewers hill. Gayton Pointe Townhomes Gayton Pointe Townhomes [Member] Gayton Pointe Townhomes. Waterside At Ironbridge Waterside at Ironbridge [Member] Waterside at Ironbridge. Carriage Homes at Wyndham Carriage Homes at Wyndham [Member] Carriage Homes at Wyndham. Legacy at Mayland Legacy at Mayland [Member] Legacy at Mayland. RICHMOND, VA Richmond VA [Member] Richmond, VA. Summit West Summit West [Member] Summit west. The Breyley The Breyley [Member] The Breyley. Lakewood Place Lakewood Place [Member] Lakewood place. Cambridge Woods Cambridge Woods [Member] Cambridge Woods. The Vintage Lofts at West End The Vintage Lofts at West End [Member] The Vintage Lofts at West End. Seabrook Seabrook [Member] Seabrook. Altamira Place Altamira Place [Member] Altamira place. Regatta Shore Regatta Shore [Member] Regatta shore. Alafaya Woods Alafaya Woods [Member] Alafaya woods. Los Altos Los Altos [Member] Los Altos. Lotus Landing Lotus Landing [Member] Lotus landing. Seville On The Green Seville on the Green [Member] Seville on the green. Ashton @ Waterford Ashton at Waterford [Member] Ashton at Waterford. Arbors at Lee Vista DCO Arbors at Lee Vista DCO [Member] Arbors at Lee Vista DCO. ORLANDO, FL Orlando Fl [Member] Orlando FL. Colonnade Colonnade [Member] Colonnade. The Preserve at Brentwood The Preserve at Brentwood [Member] The preserve at Brentwood. Garrison Square Garrison Square [Member] Garrison square. Ridge at Blue Hills Ridge at Blue Hills [Member] Ridge at Blue Hills. 21 Chelsea Twenty One Chelsea [Member] 21 Chelsea. View 34 [Member] View 34 [Member] View 34 [Member] Garden Oaks Garden Oaks [Member] Garden Oaks. Glenwood Glenwood [Member] Glenwood. Talisker of Addison Talisker of Addison [Member] Talisker of Addison. Springhaven Springhaven [Member] Springhaven. Clipper Pointe Clipper Pointe [Member] Clipper Pointe. Highlands of Preston Highlands of Preston [Member] Highlands of Preston. Residences at the Domain Residences at the Domain [Member] Residences at the Domain. Red Stone Ranch Red Stone Ranch [Member] Red Stone Ranch [Member] Lakeline Villas Lakeline Villas [Member] Lakeline Villas [Member] Pacific City [Member] Pacific City [Member] Pacific City [Member] 345 Harrison Street [Member] 345 Harrison Street [Member] 345 Harrison Street [Member] Capitol View on 14th Capitol View on 14th [Member] Capitol View on 14th [Member] 1200 East West [Member] 1200 East West [Member] 1200 East West [Member] Eleven55 Ripley [Member] Eleven55 Ripley [Member] Eleven55 Ripley [Member] Arbor Park of Alexandria [Member] Arbor Park of Alexandria [Member] Arbor Park of Alexandria [Member] Courts at Dulles [Member] Courts at Dulles [Member] Courts at Dulles [Member] Newport Village [Member] Newport Village [Member] Newport Village [Member] The Residences at Bella Terra The Residences at Bella Terra [Member] The Residences at Bella Terra [Member] Los Alisos [Member] Los Alisos [Member] Los Alisos [Member] 3032 Wilshire 3032 Wilshire [Member] 3032 Wilshire [Member] 7 Hardcourt 7 Hardcourt [Member] 7 Hardcourt [Member] Waterside Waterside [Member] Waterside. Vitruvian Vitruvian [Member] Vitruvian. Circle Towers Office Bldg Circle Towers Office Bldg [Member] Circle towers office bldg. Brookhaven Shopping Center Brookhaven Shopping Center [Member] Brookhaven shopping center. Bellevue Plaza retail Bellevue Plaza Retail [Member] Bellevue plaza retail. 1745 Shea [Member] 1745 Shea [Member] 1745 Shea [Member] Estimated depreciable lives of buildings range beginning Hurricane related impairment of assets Accumulated depreciation on retirements of fully depreciated assets Write off of accumulated depreciation on hurricane related impaired assets Unconsolidated Joint Venture Four Texas [Member] Real Estate Properties [Line Items] Real Estate Properties [Line Items] Number of Communities Deconsolidated Number of Communities Deconsolidated Number of Communities Deconsolidated Number of States in which Entity Operates Number of States in which Entity Operates Real Estate Owned (Textual) [Abstract] Real Estate Owned (Textual) [Abstract] Real estate owned. Number of apartments owned Number Of Apartment Homes Owned And Consolidated By Company Number Of Apartment Homes Owned And Consolidated By Company Number of communities acquired apartment homes are within Number of Communities Acquired Apartment Homes Are Within Number of Communities Acquired Apartment Homes Are Within Development costs excluding direct costs and capitalized interest Development Costs Excluding Direct Costs and Capitlized Interest Development Costs Excluding Direct Costs and Capitlized Interest Capitalized Interest Costs, Including Allowance for Funds Used During Construction Capitalized Interest Costs, Including Allowance for Funds Used During Construction Other Cost and Expense, Operating Other Cost and Expense, Operating Payments for (Proceeds from) Investments Payments for (Proceeds from) Investments Gain/(loss) on sales of real estate owned Deferred Gain on Sale of Property Equity Method Investments and Joint Ventures Disclosure [Text Block] Equity Method Investments and Joint Ventures Disclosure [Text Block] Segment Reporting [Abstract] Schedule of Segment Reporting Information, by Segment [Table] Schedule of Segment Reporting Information, by Segment [Table] Minimum Minimum [Member] Statement, Business Segments [Axis] Segments [Axis] Segment [Domain] Segments [Domain] Same Communities Same Communities [Member] Same Communities [Member] Same Communities Western Region Same Communities Western Region [Member] Same Communities Western Region. Same Communities Mid-Atlantic Region Same Communities Mid-Atlantic Region [Member] Same Communities Mid Atlantic Region. Same Communities Southeastern Region Same Communities Southeastern Region [Member] Same Communities Southeastern Region. Same Communities Southwestern Region Same Communities Southwestern Region [Member] Same Communities Southwestern Region. Same Communities Northeast Region [Member] Same Communities Northeast Region [Member] Same Communities Northeast Region [Member] Non-Mature communities/Other Non Mature Communities Other [Member] Non-Mature communities/Other. Total Communities [Member] Total Communities [Member] Total Communities [Member] Segment Reporting Information [Line Items] Segment Reporting Information [Line Items] Summary of rental income and NOI for UDRs reportable segments and reconciliation of NOI to loss from continuing operations Summary of Rental Income and NOI for Reportable Segments and Reconciliation of NOI to Loss from Continuing Operations [Abstract] Summary of rental income and NOI for UDRs reportable segments and reconciliation of NOI to loss from continuing operations. Reportable Segment (Textual) [Abstract] Reportable Segment (Textual) [Abstract] Reportable segment. Related party management fee percentage Related Party Transaction, Management Fee Percentage Percentage of the Operating Partnership's gross rental revenues that are charged by Taxable REIT Subisidiaries of the General Partner for management fee during the period. Number of reportable segments Number of Reportable Segments Condition for Community considered to have stabilized occupancy Percent occupancy to be considered a community Number of tenants or related group of tenants that contributed 10% or more of company total revenue Tenant or Related Group of Tenants Contributed Ten Percent or More of Company Revenue Tenant or related group of tenants contributed 10% or more of company total revenue. Reportable apartment home segment rental income Revenues Reportable apartment home segment NOI Segment Reporting Information Net Operating Income Rental income less total rental expenses, which includes real estate taxes and insurance, personnel, utilities, repair and maintenance, and administrative and marketing expenses for reportable segments. Joint venture managment and other fees Joint Venture Managment and Other Fees Joint Venture Managment and Other Fees Reconciling items: Reconciliation Item to Consolidated [Abstract] Reconciliation Item to Consolidated. Property management Segment Reporting Reconciling Items Owned Property Management Costs The aggregate costs related to management of owned properties and discontinued operations during the reporting period. Other operating expenses Other Cost And Expense Operating Including Discontinued Operations Other Cost And Expense Operating Including Discontinued Operations Depreciation and amortization Segment Reporting Reconciling Items Cost of Services Depreciation and Amortization Depreciation of property, plant and equipment directly related to services rendered to owned properties and discontinued operations by an entity during the reporting period. General and administrative Other General And Administrative Expense Including Discontinued Operations Other General And Administrative Expense Including Discontinued Operations Casualty-related (recoveries)/charges, net Insurance Recoveries Other depreciation and amortization Depreciation, Depletion and Amortization, Nonproduction Income/(loss) from unconsolidated entities Income (Loss) from Equity Method Investments Interest Expense Interest and Other Income Including Discontinued Operations Interest and Other Income Including Discontinued Operations Interest and Other Income Including Discontinued Operations Tax benefit/(expense) of taxable REIT subsidiary, net Income Tax Expense Benefit Of REIT Subsidiary Net Including Discontinued Operations Income Tax Expense Benefit Of REIT Subsidiary Net Including Discontinued Operations Gain Loss on the Sale of Real Estate, Including Discontinued Operations Gain Loss on the Sale of Real Estate, Including Discontinued Operations Gain Loss on the Sale of Real Estate, Including Discontinued Operations Redeemable non-controlling interests in OP Net Income (Loss) Attributable to Redeemable Noncontrolling Interest Noncontrolling Interest in Net Income (Loss) Other Noncontrolling Interests, Nonredeemable Noncontrolling Interest in Net Income (Loss) Other Noncontrolling Interests, Nonredeemable Net (loss)/gain on sale of depreciable property Segment Reporting Reconciling Items Gain Loss on Sale of Property Gain on sale of depreciable property, including RE3 gains, net of tax. Net income/(loss) attributable to Entity Net Income (Loss) Attributable to Parent Details of assets of UDR's reportable segments Details of Assets of Company's Reportable Segments [Abstract] Details of assets of company's reportable segments. Reportable apartment home segment assets: Reportable Apartment Home Segment Assets [Abstract] Reportable apartment home segment assets. Total segment assets Accumulated depreciation Reconciling items: Segment Reconciliation [Abstract] Deferred financing costs, net Notes receivable Reportable Segments Additional (Textual) [Abstract] Reportable Segments Additional (Textual) [Abstract] Reportable segments additional. Capital expenditures related to segments Long-term Purchase Commitment [Table] Long-term Purchase Commitment [Table] Wholly-owned — under development Wholly Owned Properties Under Development [Member] Wholly Owned Properties Under Development [Member] Wholly-owned — redevelopment Wholly Owned Properties Redevelopment [Member] Wholly Owned Properties Redevelopment [Member] Unconsolidated joint ventures Unconsolidated Properties [Member] Long-term Purchase Commitment [Line Items] Long-term Purchase Commitment [Line Items] Number of Properties Costs Incurred to Date Cost Incurred to Date -- None. No documentation exists for this element. -- Purchase Commitment, Remaining Minimum Amount Committed Purchase Commitment, Remaining Minimum Amount Committed Expected Costs to Complete Expected Costs to Complete Remaining capitalized project costs to be incurred as of balance sheet date. Average Ownership Stake Ownership Stake -- None. No documentation exists for this element. -- Borrowings outstanding Weighted average daily borrowings during the period ended Line of Credit Facility, Average Outstanding Amount Maximum daily borrowings during the period ended Line of Credit Facility, Maximum Amount Outstanding During Period Weighted average interest rate during the period ended Line of Credit Facility, Interest Rate During Period Taxable Distributions Paid Per Common Share [Abstract] Taxable distributions paid per common share. Ordinary income Taxable Distributions Paid Per Common Share Ordinary Income The tax status of distribution per common share of an entity's earnings to common stockholders classified as ordinary taxable dividend. Taxable Distributions Paid Per Common Share Qualified Ordinary Income Taxable Distributions Paid Per Common Share Qualified Ordinary Income Taxable Distributions Paid Per Common Share Qualified Ordinary Income Long-term capital gain Taxable Distributions Paid Per Common Share Long Term Capital Gain The tax status of distribution per common share of an entity's earnings to common stockholders classified as long term capital gain. Capital gain income from assets held longer than one year are generally taxed at a special long-term capital gain rate. Unrecapture section 1250 gain Taxable Distributions Paid Per Common Share Unrecapture Section Gain Tax status of distributions per common share paid to common shareholders classified as unrecapture section 1250 gain, which is a type of depreciation-recapture income that is realized on the sale of depreciable real estate. Unrecaptured Section 1250 income is taxed at a 25% maximum capital gains rate (or in some cases less). Taxable distributions per common share Common Stock, Dividends, Per Share, Cash Paid Statement of Comprehensive Income [Abstract] Net income/(loss) Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Other comprehensive income/(loss), including portion attributable to noncontrolling interests: Other Comprehensive Income (Loss), Net of Tax [Abstract] Other comprehensive income/(loss) - derivative instruments: Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax [Abstract] Unrealized holding gain/(loss) Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax (Gain)/loss reclassified into earnings from other comprehensive income/(loss) Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, before Tax Other comprehensive income/(loss), including portion attributable to noncontrolling interests Other Comprehensive Income (Loss), Net of Tax Comprehensive income/(loss) Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest Comprehensive (income)/loss attributable to noncontrolling interests Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest Comprehensive income/(loss) attributable to Entity Comprehensive Income (Loss), Net of Tax, Attributable to Parent Notes receivable Schedule of Accounts, Notes, Loans and Financing Receivable [Table Text Block] Computation of basic and diluted earning per share Summary of rental income and NOI for UDRs reportable segments and reconciliation of NOI to loss from continuing operations Reconciliation of Operating Profit (Loss) from Segments to Consolidated [Table Text Block] Details of assets of UDR's reportable segments Reconciliation of Assets from Segment to Consolidated [Table Text Block] Disclosure of Compensation Related Costs, Share-based Payments [Abstract] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Award Type [Axis] Award Type [Axis] Award Type [Domain] Equity Award [Domain] Stock Options [Member] Employee Stock Option [Member] Restricted Stock Restricted Stock [Member] Outstanding [Member] Outstanding [Member] Outstanding [Member] Exercisable [Member] Exercisable [Member] Exercisable [Member] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized Options Outstanding, Number of Options Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward] Balance, December 31, 2011 Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number Granted Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross Exercised Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period Balance, December 31, 2012 Options Outstanding, Weighted Average Exercise Price Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]