Noncontrolling Interests (Details) (USD $) In Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Redeemable noncontrolling interests in the Operating Partnership
Beginning redeemable noncontrolling interests in the OP			$ 119,057
Mark to market adjustment to redeemable noncontrolling interests in the OP			9,212
Conversion of OP Units to Common Stock	(48)	(336)	(48)	(551)
Net loss attributable to redeemable noncontrolling interest in the OP	221	(1,064)	(611)	(2,069)
OP units issued for partial consideration in community acquisition			62,879
Distributions to redeemable noncontrolling interests in the OP			(2,951)
Net income attributable to non-controlling interest			(229)
Ending redeemable noncontrolling interests in the OP	187,309		187,309
Net loss attributable to common stockholders and transfers from redeemable noncontrolling interests
Net income/(loss) attributable to common stockholders	12,149	(28,968)	(18,094)	(55,403)
Conversion of OP units to UDR Common Stock	48	336	48	551
Change in equity from net (loss)/income attributable to common stockholders and conversion of OP units to UDR Common Stock	12,197	(28,632)	(18,046)	(54,852)
Noncontrolling Interest (Textuals) [Abstract]
Net income attributable to non-controlling interests	$ (37)	$ (45)	$ (88)	$ (80)

Allocation to redeemable non-controllable interests.

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Change in equity from net (loss)/income attributable to common stockholders and conversion of operating partnership units to company's Common Stock.

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- Definition

Conversion of Operating Partnership Units to Common Stock.

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- Definition

Amount of distributions during the period on redeemable noncontrolling interests in the OP.

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Net loss attributable to common stockholders and transfers from redeemable noncontrolling interests.

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Noncontrolling Interest Textuals.

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- Definition

Operating partnership units Issued For Partial Consideration In Community Acquisition.

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- Definition

Rollforward of redeemable noncontrolling interests in the Operating Partnership during the period.

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- Definition

Change in noncontrolling interest during the period as a result of a change in the redemption value of redeemable noncontrolling interest.

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- Definition

Amount of net income or loss for the period allocated to noncontrolling shareholders, unit holders, partners, or other equity holders in one or more of the entities consolidated into the reporting entity's financial statements other than those noncontrolling interests already defined within the taxonomy.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Research Bulletin (ARB)
-Number 51
-Paragraph 38
-Subparagraph a
-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 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.19)
-URI http://asc.fasb.org/extlink&oid=6880815&loc=d3e20235-122688

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Research Bulletin (ARB)
-Number 51
-Paragraph 38
-Subparagraph c(1)
-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.

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The portion of net income or loss for the period attributable to redeemable noncontrolling interest (if any) deducted in order to derive the portion attributable to the parent. This element should be used for redeemable noncontrolling interests that are classified within temporary equity.

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- Definition

Net income after adjustments for dividends on preferred stock (declared in the period) and/or cumulative preferred stock (accumulated for the period).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 128
-Paragraph 9
-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 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=6920599&loc=d3e1377-109256

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The carrying value (book value) of an entity's issued and outstanding stock which is not included within permanent equity in Stockholders Equity. Temporary equity is a security with redemption features that are outside the control of the issuer, is not classified as an asset or liability in conformity with GAAP, and is not mandatorily redeemable. Includes any type of security that is redeemable at a fixed or determinable price or on a fixed or determinable date or dates, is redeemable at the option of the holder, or has conditions for redemption which are not solely within the control of the issuer. If convertible, the issuer does not control the actions or events necessary to issue the maximum number of shares that could be required to be delivered under the conversion option if the holder exercises the option to convert the stock to another class of equity. If the security is a warrant or a rights issue, the warrant or rights issue is considered to be temporary equity if the issuer cannot demonstrate that it would be able to deliver upon the exercise of the option by the holder in all cases. Includes stock with a put option held by an ESOP and stock redeemable by a holder only in the event of a change in control of the issuer.

+ 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 210.5-02.27(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Emerging Issues Task Force (EITF)
-Number D-98
-Paragraph 2
-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 SEC
-Name Regulation S-X (SX)
-Number 210
-Article 4
-Section 08
-Paragraph i

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 28
-Subparagraph a
-Article 5

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