2.4.0.82410404 - Disclosure - Secured and Unsecured Debt (Details 2)truefalsefalse1false USDfalsefalseD2013Q2YTDhttp://www.sec.gov/CIK0000074208duration2013-01-01T00:00:002013-06-30T00:00:00numberStandardhttp://www.xbrl.org/2003/instancepurexbrli0usdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170$2false USDfalsefalse$I2012Q4http://www.sec.gov/CIK0000074208instant2012-12-31T00:00:000001-01-01T00:00:00usdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$3false USDfalsefalse$I2012Q2http://www.sec.gov/CIK0000074208instant2012-06-30T00:00:000001-01-01T00:00:00usdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$1true 3us-gaap_DebtInstrumentLineItemsus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Debt Instrument [Line Items]2false 4udr_SecuredDebtEncumbersRealEstateOwnedAmountudr_falsecreditinstantfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truefalsefalse22000000002200000000USD$falsetruefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalsexbrli:monetaryItemTypemonetarySecured Debt, Encumbers Real Estate Owned, Amount.No definition available.false2Secured Debt, Encumbers Real Estate Owned, Amount3false 4udr_SecuredDebtEncumbersRealEstateOwnedPercentudr_falsenainstantfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truetruefalse0.2710.271falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalsenum:percentItemTypepureSecured Debt, Encumbers Real Estate Owned, Percent.No definition available.false0Secured Debt, Encumbers Real Estate Owned, Percent4false 4udr_DebtInstrumentWeightedAverageYearsToMaturityudr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse004 years 2 months 26 daysfalsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalsexbrli:durationItemTypenaDebt instrument weighted average years to maturity.No definition available.false0Debt Instrument Weighted Average Years to Maturity5false 4us-gaap_DebtInstrumentUnamortizedDiscountus-gaap_truedebitinstantfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truefalsefalse1440000014400000USD$falsefalsefalse2falsefalsefalse00falsefalsefalse3truefalsefalse1690000016900000USD$falsefalsefalsexbrli:monetaryItemTypemonetaryThe amount of debt discount that was originally recognized at the issuance of the instrument that has yet to be amortized.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 45 -Paragraph 1A -URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28541-108399 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name FASB Staff Position (FSP) -Number APB14-1 -Paragraph 31 -Subparagraph b -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 55 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=6584090&loc=d3e28878-108400 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Principles Board Opinion (APB) -Number 21 -Paragraph 16, 20 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. false2Unamortized discount6true 4us-gaap_LongTermDebtByMaturityAbstractus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Aggregate maturities of secured debt7false 5us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonthsus-gaap_truecreditinstantfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truefalsefalse66390006639000USD$falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalsexbrli:monetaryItemTypemonetaryAmount of long-term debt, sinking fund requirements, and other securities redeemable at fixed or determinable prices and dates maturing in the next fiscal year following the latest fiscal year.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 10 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6802200&loc=d3e1835-112601 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 47 -Paragraph 10 -Subparagraph b -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. false220138false 5us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwous-gaap_truecreditinstantfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truefalsefalse359562000359562000USD$falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalsexbrli:monetaryItemTypemonetaryAmount of long-term debt, sinking fund requirements, and other securities redeemable at fixed or determinable prices and dates maturing in the second fiscal year following the latest fiscal year.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 10 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6802200&loc=d3e1835-112601 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 47 -Paragraph 10 -Subparagraph b -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. false220149false 5us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThreeus-gaap_truecreditinstantfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truefalsefalse750080000750080000USD$falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalsexbrli:monetaryItemTypemonetaryAmount of long-term debt, sinking fund requirements, and other securities redeemable at fixed or determinable prices and dates maturing in the third fiscal year following the latest fiscal year.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 10 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6802200&loc=d3e1835-112601 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 47 -Paragraph 10 -Subparagraph b -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. false2201510false 5us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFourus-gaap_truecreditinstantfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truefalsefalse568925000568925000USD$falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalsexbrli:monetaryItemTypemonetaryAmount of long-term debt, sinking fund requirements, and other securities redeemable at fixed or determinable prices and dates maturing in the fourth fiscal year following the latest fiscal year.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 10 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6802200&loc=d3e1835-112601 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 47 -Paragraph 10 -Subparagraph b -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. false2201611false 5us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFiveus-gaap_truecreditinstantfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truefalsefalse243374000243374000USD$falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalsexbrli:monetaryItemTypemonetaryAmount of long-term debt, sinking fund requirements, and other securities redeemable at fixed or determinable prices and dates maturing in the fifth fiscal year following the latest fiscal year.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 10 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6802200&loc=d3e1835-112601 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 47 -Paragraph 10 -Subparagraph b -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. false2201712false 5us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalAfterYearFiveus-gaap_truecreditinstantfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truefalsefalse14661430001466143000USD$falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalsexbrli:monetaryItemTypemonetaryAmount of long-term debt, sinking fund requirements, and other securities redeemable at fixed or determinable prices and dates maturing after the fifth fiscal year following the latest fiscal year.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 10 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6802200&loc=d3e1835-112601 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 47 -Paragraph 10 -Subparagraph b -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. false2Thereafter13false 5us-gaap_SecuredDebtus-gaap_truecreditinstantfalsefalsefalsefalsefalsefalsefalsefalsetotalLabel1truefalsefalse13850340001385034000USD$falsefalsefalse2truefalsefalse14301350001430135000USD$falsefalsefalse3falsefalsefalse00falsefalsefalsexbrli:monetaryItemTypemonetaryCarrying value as of the balance sheet date, including the current and noncurrent portions, of collateralized debt obligations (with maturities initially due after one year or beyond the operating cycle, if longer). Such obligations include mortgage loans, chattel loans, and any other borrowings secured by assets of the borrower.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03.16) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.16) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 16 -Article 9 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 19, 20, 22 -Article 5 true2Total14false 4udr_SecuredDebtUnencumberedRealEstateOwnedAmountudr_falsecreditinstantfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truefalsefalse58000000005800000000USD$falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalsexbrli:monetaryItemTypemonetarySecured Debt, Unencumbered Real Estate Owned, Amount.No definition available.false2Secured Debt, Unencumbered Real Estate Owned, Amount15false 4udr_SecuredDebtUnencumberedRealEstateOwnedPercentudr_falsenainstantfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truetruefalse0.7290.729falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalsenum:percentItemTypepureSecured Debt, Unencumbered Real Estate Owned, Percent.No definition available.false0Secured Debt, Unencumbered Real Estate Owned, Percent16false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalse4false truefalseD2013Q2YTD_us-gaap_DebtInstrumentAxis_udr_FixedRateDebtMemberhttp://www.sec.gov/CIK0000074208duration2013-01-01T00:00:002013-06-30T00:00:00falsefalseFixed Rate Debt [Member]us-gaap_DebtInstrumentAxisxbrldihttp://xbrl.org/2006/xbrldiudr_FixedRateDebtMemberus-gaap_DebtInstrumentAxisexplicitMembernanafalse0Fixed Rate Debt [Member]17true 3us-gaap_DebtInstrumentLineItemsus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Debt Instrument [Line Items]18false 4udr_DebtInstrumentWeightedAverageYearsToMaturityudr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse004 years 5 months 14 daysfalsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalsexbrli:durationItemTypenaDebt instrument weighted average years to maturity.No definition available.false0Debt Instrument Weighted Average Years to Maturity19false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalse5false truefalseD2013Q2YTD_us-gaap_DebtInstrumentAxis_udr_VariableRateDebtMemberhttp://www.sec.gov/CIK0000074208duration2013-01-01T00:00:002013-06-30T00:00:00falsefalseVariable Rate Debt [Member]us-gaap_DebtInstrumentAxisxbrldihttp://xbrl.org/2006/xbrldiudr_VariableRateDebtMemberus-gaap_DebtInstrumentAxisexplicitMembernanafalse0Variable Rate Debt [Member]20true 3us-gaap_DebtInstrumentLineItemsus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Debt Instrument [Line Items]21false 4udr_DebtInstrumentWeightedAverageYearsToMaturityudr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse007 years 11 months 6 daysfalsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalsexbrli:durationItemTypenaDebt instrument weighted average years to maturity.No definition available.false0Debt Instrument Weighted Average Years to Maturity22false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalse6false truefalseD2013Q2YTD_us-gaap_LongtermDebtTypeAxis_udr_Twopointsixeightpercenttermnotesduedecember2016Memberhttp://www.sec.gov/CIK0000074208duration2013-01-01T00:00:002013-06-30T00:00:00falsefalse2.68% Term Notes due December 2016 [Member]us-gaap_LongtermDebtTypeAxisxbrldihttp://xbrl.org/2006/xbrldiudr_Twopointsixeightpercenttermnotesduedecember2016Memberus-gaap_LongtermDebtTypeAxisexplicitMembernumberStandardhttp://www.xbrl.org/2003/instancepurexbrli0nanafalse02.68% Term Notes due December 2016 [Member]23true 3us-gaap_DebtInstrumentLineItemsus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Debt Instrument [Line Items]24false 4udr_DebtInstrumentWeightedAverageYearsToMaturityudr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse004 years 11 months 4 daysfalsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalsexbrli:durationItemTypenaDebt instrument weighted average years to maturity.No definition available.false0Debt Instrument Weighted Average Years to Maturity25false 4us-gaap_DebtInstrumentInterestRateStatedPercentageus-gaap_truenainstantfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruefalse0.02500.0250falsefalsefalse2truetruefalse0.02680.0268falsefalsefalse3falsefalsefalse00falsefalsefalsenum:percentItemTypepureInterest rate stated in the contractual debt agreement.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 22 -Article 5 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(1)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 false0Debt Instrument, Interest Rate, Stated Percentage26false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalse8false USDtruefalseD2013Q2YTD_us-gaap_LongtermDebtTypeAxis_udr_FourPointSixThreePercentTermMediumNotesDueJanuaryTwoThousandTwentyTwoMemberhttp://www.sec.gov/CIK0000074208duration2013-01-01T00:00:002013-06-30T00:00:00falsefalseFour Point Six Three Percent Term Medium Notes Due January Two Thousand Twenty-Two [Member]us-gaap_LongtermDebtTypeAxisxbrldihttp://xbrl.org/2006/xbrldiudr_FourPointSixThreePercentTermMediumNotesDueJanuaryTwoThousandTwentyTwoMemberus-gaap_LongtermDebtTypeAxisexplicitMembernumberStandardhttp://www.xbrl.org/2003/instancepurexbrli0usdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170$nanafalse0Four Point Six Three Percent Term Medium Notes Due January Two Thousand Twenty-Two [Member]27true 3us-gaap_DebtInstrumentLineItemsus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Debt Instrument [Line Items]28false 4udr_DebtInstrumentWeightedAverageYearsToMaturityudr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse008 years 6 months 10 daysfalsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalsexbrli:durationItemTypenaDebt instrument weighted average years to maturity.No definition available.false0Debt Instrument Weighted Average Years to Maturity29false 4us-gaap_DebtInstrumentInterestRateStatedPercentageus-gaap_truenainstantfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruefalse0.04630.0463falsefalsefalse2truetruefalse0.04630.0463falsefalsefalse3falsefalsefalse00falsefalsefalsenum:percentItemTypepureInterest rate stated in the contractual debt agreement.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 22 -Article 5 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(1)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 false0Debt Instrument, Interest Rate, Stated Percentage30false 4us-gaap_DebtInstrumentUnamortizedDiscountus-gaap_truedebitinstantfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truefalsefalse30610003061000USD$falsetruefalse2truefalsefalse32410003241000USD$falsetruefalse3falsefalsefalse00falsefalsefalsexbrli:monetaryItemTypemonetaryThe amount of debt discount that was originally recognized at the issuance of the instrument that has yet to be amortized.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 45 -Paragraph 1A -URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28541-108399 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name FASB Staff Position (FSP) -Number APB14-1 -Paragraph 31 -Subparagraph b -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 55 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=6584090&loc=d3e28878-108400 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Principles Board Opinion (APB) -Number 21 -Paragraph 16, 20 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. false2Unamortized discount31false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalse10false truefalseD2013Q2YTD_us-gaap_DebtInstrumentAxis_udr_FixedRateDebtMember_us-gaap_LongtermDebtTypeAxis_us-gaap_MortgagesMemberhttp://www.sec.gov/CIK0000074208duration2013-01-01T00:00:002013-06-30T00:00:00falsefalseMortgages Notes Payable [Member]us-gaap_LongtermDebtTypeAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_MortgagesMemberus-gaap_LongtermDebtTypeAxisexplicitMemberfalsefalseFixed Rate Debt [Member]us-gaap_DebtInstrumentAxisxbrldihttp://xbrl.org/2006/xbrldiudr_FixedRateDebtMemberus-gaap_DebtInstrumentAxisexplicitMembernanafalse0Mortgages Notes Payable [Member] | Fixed Rate Debt [Member]32true 3us-gaap_DebtInstrumentLineItemsus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Debt Instrument [Line Items]33false 4udr_DebtInstrumentWeightedAverageYearsToMaturityudr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse003 years 0 months 3 daysfalsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalsexbrli:durationItemTypenaDebt instrument weighted average years to maturity.No definition available.false0Debt Instrument Weighted Average Years to Maturity34false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalse11false truefalseD2013Q2YTD_us-gaap_DebtInstrumentAxis_udr_VariableRateDebtMember_us-gaap_LongtermDebtTypeAxis_us-gaap_MortgagesMemberhttp://www.sec.gov/CIK0000074208duration2013-01-01T00:00:002013-06-30T00:00:00falsefalseMortgages Notes Payable [Member]us-gaap_LongtermDebtTypeAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_MortgagesMemberus-gaap_LongtermDebtTypeAxisexplicitMemberfalsefalseVariable Rate Debt [Member]us-gaap_DebtInstrumentAxisxbrldihttp://xbrl.org/2006/xbrldiudr_VariableRateDebtMemberus-gaap_DebtInstrumentAxisexplicitMembernanafalse0Mortgages Notes Payable [Member] | Variable Rate Debt [Member]35true 3us-gaap_DebtInstrumentLineItemsus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Debt Instrument [Line Items]36false 4udr_DebtInstrumentWeightedAverageYearsToMaturityudr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse003 monthsfalsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalsexbrli:durationItemTypenaDebt instrument weighted average years to maturity.No definition available.false0Debt Instrument Weighted Average Years to Maturity37false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalse12false truefalseD2013Q2YTD_us-gaap_DebtInstrumentAxis_udr_VariableRateDebtMember_us-gaap_LongtermDebtTypeAxis_udr_TaxExemptNotesPayableMemberhttp://www.sec.gov/CIK0000074208duration2013-01-01T00:00:002013-06-30T00:00:00falsefalseTax Exempt Notes Payable [Member]us-gaap_LongtermDebtTypeAxisxbrldihttp://xbrl.org/2006/xbrldiudr_TaxExemptNotesPayableMemberus-gaap_LongtermDebtTypeAxisexplicitMemberfalsefalseVariable Rate Debt [Member]us-gaap_DebtInstrumentAxisxbrldihttp://xbrl.org/2006/xbrldiudr_VariableRateDebtMemberus-gaap_DebtInstrumentAxisexplicitMembernanafalse0Tax Exempt Notes Payable [Member] | Variable Rate Debt [Member]38true 3us-gaap_DebtInstrumentLineItemsus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Debt Instrument [Line Items]39false 4udr_DebtInstrumentWeightedAverageYearsToMaturityudr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse009 years 8 months 8 daysfalsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalsexbrli:durationItemTypenaDebt instrument weighted average years to maturity.No definition available.false0Debt Instrument Weighted Average Years to Maturity40false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalse13false truefalseD2013Q2YTD_us-gaap_DebtInstrumentAxis_udr_FixedRateDebtMember_us-gaap_LongtermDebtTypeAxis_us-gaap_LineOfCreditMemberhttp://www.sec.gov/CIK0000074208duration2013-01-01T00:00:002013-06-30T00:00:00falsefalseFannie Mae credit facilities [Member]us-gaap_LongtermDebtTypeAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_LineOfCreditMemberus-gaap_LongtermDebtTypeAxisexplicitMemberfalsefalseFixed Rate Debt [Member]us-gaap_DebtInstrumentAxisxbrldihttp://xbrl.org/2006/xbrldiudr_FixedRateDebtMemberus-gaap_DebtInstrumentAxisexplicitMembernanafalse0Fannie Mae credit facilities [Member] | Fixed Rate Debt [Member]41true 3us-gaap_DebtInstrumentLineItemsus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Debt Instrument [Line Items]42false 4udr_DebtInstrumentWeightedAverageYearsToMaturityudr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse005 years 6 months 3 daysfalsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalsexbrli:durationItemTypenaDebt instrument weighted average years to maturity.No definition available.false0Debt Instrument Weighted Average Years to Maturity43false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalse14false truefalseD2013Q2YTD_us-gaap_DebtInstrumentAxis_udr_VariableRateDebtMember_us-gaap_LongtermDebtTypeAxis_us-gaap_LineOfCreditMemberhttp://www.sec.gov/CIK0000074208duration2013-01-01T00:00:002013-06-30T00:00:00falsefalseFannie Mae credit facilities [Member]us-gaap_LongtermDebtTypeAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_LineOfCreditMemberus-gaap_LongtermDebtTypeAxisexplicitMemberfalsefalseVariable Rate Debt [Member]us-gaap_DebtInstrumentAxisxbrldihttp://xbrl.org/2006/xbrldiudr_VariableRateDebtMemberus-gaap_DebtInstrumentAxisexplicitMembernanafalse0Fannie Mae credit facilities [Member] | Variable Rate Debt [Member]44true 3us-gaap_DebtInstrumentLineItemsus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Debt Instrument [Line Items]45false 4udr_DebtInstrumentWeightedAverageYearsToMaturityudr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse005 years 0 months 7 daysfalsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalsexbrli:durationItemTypenaDebt instrument weighted average years to maturity.No definition available.false0Debt Instrument Weighted Average Years to Maturity46false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalse15false truefalseI2013Q2_us-gaap_LineOfCreditFacilityAxis_udr_UdrBankCreditFacilityMemberhttp://www.sec.gov/CIK0000074208instant2013-06-30T00:00:000001-01-01T00:00:00falsefalseUDR Bank Credit Facility [Member]us-gaap_LineOfCreditFacilityAxisxbrldihttp://xbrl.org/2006/xbrldiudr_UdrBankCreditFacilityMemberus-gaap_LineOfCreditFacilityAxisexplicitMembernumberStandardhttp://www.xbrl.org/2003/instancepurexbrli0nanafalse0UDR Bank Credit Facility [Member]47true 3us-gaap_DebtInstrumentLineItemsus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Debt Instrument [Line Items]48false 4us-gaap_DebtInstrumentBasisSpreadOnVariableRateus-gaap_truenainstantfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truetruefalse0.0110.011falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalsenum:percentItemTypepureThe percentage points added to the reference rate to compute the variable rate on the debt instrument.No definition available.false0Debt Instrument, Basis Spread on Variable Rate49false 4udr_DebtInstrumentFacilityFeeBasisSpreadOnVariableRateudr_falsenainstantfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truetruefalse0.00200.0020falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalsenum:percentItemTypepureDebt Instrument Facility Fee, Basis Spread on Variable RateNo definition available.false0Debt Instrument Facility Fee, Basis Spread on Variable RatefalseSecured and Unsecured Debt (Details 2) (USD $)NoRoundingUnKnownUnKnownUnKnowntruefalsefalseSheethttp://www.udr.com/role/SecuredAndUnsecuredDebtDetails2349