Debt instrument weighted average years to maturity.

No definition available.

Name:	udr_DebtInstrumentWeightedAverageYearsToMaturity
Namespace Prefix:	udr_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

+ References

Reference 1: 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 2: 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 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 20, 22

-Article 5

+ Details

Name:	us-gaap_LineOfCredit
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Average amount borrowed under the credit facility during the period.

+ References

No definition available.

+ Details

Name:	us-gaap_LineOfCreditFacilityAverageOutstandingAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The effective interest rate at the end of the reporting period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.19(b),22(b))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 22

-Article 5

+ Details

Name:	us-gaap_LineOfCreditFacilityInterestRateAtPeriodEnd
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The effective interest rate during the reporting period.

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityInterestRateDuringPeriod
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Maximum amount borrowed under the credit facility at any time during the period.

+ References

No definition available.

+ Details

Name:	us-gaap_LineOfCreditFacilityMaximumAmountOutstandingDuringPeriod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	us-gaap_LongtermDebtTypeAxis=udr_FannieMaeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=udr_UnitedDominionRealityLPMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=udr_FixedRateDebtMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_MortgagesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_LineOfCreditMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=udr_VariableRateDebtMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=udr_TaxExemptNotesPayableMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Debt (UNITED DOMINION REALTY, L.P.) (Details 1) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2013	Dec. 31, 2014
Debt Instrument [Line Items]
Debt Instrument Weighted Average Years to Maturity	4 years 29 days
Borrowings outstanding	$ 2,300		$ 1,900
Fannie Mae [Member]
Debt Instrument [Line Items]
Borrowings outstanding	815,666		$ 834,282
Weighted average daily borrowings during the period ended	830,434	$ 835,873
Maximum daily borrowings during the period ended	$ 834,003	$ 837,564
Weighted average interest rate during the period ended	4.01%	4.10%
Interest rate at the end of the period	4.05%		4.00%
United Dominion Reality L.P. [Member]
Debt Instrument [Line Items]
Debt Instrument Weighted Average Years to Maturity	3 years 6 months 14 days
United Dominion Reality L.P. [Member] \| Fannie Mae [Member]
Debt Instrument [Line Items]
Borrowings outstanding	$ 511,511		$ 526,588
Weighted average daily borrowings during the period ended	520,773	$ 527,592
Maximum daily borrowings during the period ended	$ 523,011	$ 528,659
Weighted average interest rate during the period ended	3.80%	4.10%
Interest rate at the end of the period	3.90%		4.00%
Fixed Rate Debt [Member]
Debt Instrument [Line Items]
Debt Instrument Weighted Average Years to Maturity	2 years 6 months 10 days
Fixed Rate Debt [Member] \| Mortgages [Member]
Debt Instrument [Line Items]
Debt Instrument Weighted Average Years to Maturity	1 year 20 days
Fixed Rate Debt [Member] \| Line of Credit [Member]
Debt Instrument [Line Items]
Debt Instrument Weighted Average Years to Maturity	3 years 6 months 14 days
Fixed Rate Debt [Member] \| United Dominion Reality L.P. [Member]
Debt Instrument [Line Items]
Debt Instrument Weighted Average Years to Maturity	2 years 6 months
Fixed Rate Debt [Member] \| United Dominion Reality L.P. [Member] \| Mortgages [Member]
Debt Instrument [Line Items]
Debt Instrument Weighted Average Years to Maturity	1 year 1 month 6 days
Fixed Rate Debt [Member] \| United Dominion Reality L.P. [Member] \| Line of Credit [Member]
Debt Instrument [Line Items]
Debt Instrument Weighted Average Years to Maturity	4 years 25 days
Variable Rate Debt [Member]
Debt Instrument [Line Items]
Debt Instrument Weighted Average Years to Maturity	5 years 3 months
Variable Rate Debt [Member] \| Mortgages [Member]
Debt Instrument [Line Items]
Debt Instrument Weighted Average Years to Maturity	1 year 6 months 25 days
Variable Rate Debt [Member] \| Tax Exempt Notes Payable [Member]
Debt Instrument [Line Items]
Debt Instrument Weighted Average Years to Maturity	7 years 8 months 8 days
Variable Rate Debt [Member] \| Line of Credit [Member]
Debt Instrument [Line Items]
Debt Instrument Weighted Average Years to Maturity	4 years 9 months 10 days
Variable Rate Debt [Member] \| United Dominion Reality L.P. [Member]
Debt Instrument [Line Items]
Debt Instrument Weighted Average Years to Maturity	7 years 1 month 17 days
Variable Rate Debt [Member] \| United Dominion Reality L.P. [Member] \| Tax Exempt Notes Payable [Member]
Debt Instrument [Line Items]
Debt Instrument Weighted Average Years to Maturity	16 years 8 months 19 days
Variable Rate Debt [Member] \| United Dominion Reality L.P. [Member] \| Line of Credit [Member]
Debt Instrument [Line Items]
Debt Instrument Weighted Average Years to Maturity	5 years 8 months 1 day