Capital Structure (UNITED DOMINION REALTY, L.P.) (Details) $ in Thousands	6 Months Ended
Jun. 30, 2015 USD ($) $ / Units shares	Dec. 31, 2014 USD ($) shares
Limited Partners' Capital Account [Line Items]
Redeemable Noncontrolling Interest, Equity, Carrying Amount \| $	$ 290,278
Percentage of units	4.90%
Redeemable noncontrolling interests in the Operating Partnership \| $	$ 290,278	$ 282,480
United Dominion Reality L.P. [Member]
Limited Partners' Capital Account [Line Items]
General Partnership units outstanding	110,883	110,883
Limited partnership units owned	183,167,815	183,167,815
Limited Partners' Capital Account, Required Period To Be Outstanding Before Unit is Redeemable	1 year
UDR, Inc. [Member]
Limited Partners' Capital Account [Line Items]
Limited partnership units owned	174,105,126	174,002,342
Percentage of units	95.10%	95.00%
Non-affiliated Partners [Member]
Limited Partners' Capital Account [Line Items]
Limited partnership units owned	9,062,689	9,165,473
Percentage of units	4.90%	5.00%
Class A Limited Partner [Member]
Limited Partners' Capital Account [Line Items]
Limited partnership units owned	1,751,671
Cumulative, annual, non-compounded preferred return on Class A Partnership units	8.00%
Value of Class A Partnership units (in dollars per unit) \| $ / Units	16.61
Class A Limited Partner [Member] \| United Dominion Reality L.P. [Member]
Limited Partners' Capital Account [Line Items]
Limited partnership units owned	1,873,332	1,873,332
Class A Limited Partner [Member] \| UDR, Inc. [Member]
Limited Partners' Capital Account [Line Items]
Limited partnership units owned	121,661

Limited Partners' Capital Account, Required Period To Be Outstanding Before Unit is Redeemable

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Cumulative, annual, non-compounded preferred return percentage of Class A Partnership units.

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Value per Class A Partnership unit which preferred return percentage is based.

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Limited Partners Capital Account Units Outstanding Percentage.

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The number of general partner units outstanding.

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The number of limited partner units outstanding.

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

-Publisher FASB

-Name Accounting Standards Codification

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As of the reporting date, the aggregate carrying amount of all noncontrolling interests which are redeemable by the (parent) entity (1) at a fixed or determinable price on a fixed or determinable date, (2) at the option of the holder of the noncontrolling interest, or (3) upon occurrence of an event that is not solely within the control of the (parent) entity. This item includes noncontrolling interest holder's ownership (or holders' ownership) regardless of the type of equity interest (common, preferred, other) including all potential organizational (legal) forms of the investee entity.

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As of the reporting date, the carrying amount of noncontrolling interests which are redeemable by the (parent) entity (1) at a fixed or determinable price on a fixed or determinable date, (2) at the option of the holder of the noncontrolling interest, or (3) upon occurrence of an event that is not solely within the control of the (parent) entity. The noncontrolling interest holder's ownership (or holders' ownership) may be in the form of common shares (regardless of class), limited partnership units (regardless of class), non-preferential membership interests, or any other form of common equity regardless of investee entity legal form.

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