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Consolidation and Basis of Presentation (Details)	Dec. 31, 2015 Communities	Dec. 31, 2015	Dec. 31, 2015 USD ($)	Dec. 31, 2015 Apartment_Homes	Dec. 31, 2015 shares	Dec. 31, 2014 USD ($) shares	Dec. 31, 2013 shares	Dec. 31, 2012 shares
Consolidation and Basis of Presentation [Line Items]
Number of Real Estate Properties	133	2
Investment Building and Building Improvements, and Furniture, Fixtures and Equipment | $			$ 7,046,622,000			$ 6,225,406,000
Consolidation And Basis Of Presentation (Textual) [Abstract]
Number of markets operating within | $			18
Number of apartments owned | Apartment_Homes				40,728
Joint venture, number of homes in communities | Apartment_Homes				6,696
Operating Partnership outstanding units					183,278,698	183,278,698
OP units outstanding related to limited partner					183,278,698	183,278,698	183,278,698	184,281,254
General Partner [Member]
Consolidation And Basis Of Presentation (Textual) [Abstract]
OP units outstanding related to limited partner					174,225,399	174,113,225
Percentage of units outstanding owned by limited partners						95.00%
Limited Partner [Member]
Consolidation And Basis Of Presentation (Textual) [Abstract]
Percentage of units outstanding owned by limited partners		95.10%
Non-affiliated Partners
Consolidation And Basis Of Presentation (Textual) [Abstract]
OP units outstanding related to limited partner					9,053,299	9,165,473
Percentage of units outstanding owned by limited partners		4.90%				5.00%
UDR Lighthouse DownREIT L.P. [Member]
Consolidation And Basis Of Presentation (Textual) [Abstract]
Operating Partnership outstanding units					32,367,380
United Dominion Reality L.P. | UDR Lighthouse DownREIT L.P. [Member]
Consolidation And Basis Of Presentation (Textual) [Abstract]
Operating Partnership outstanding units					13,470,651
Percentage of units outstanding owned by limited partners		41.60%
General Partner [Member] | UDR Lighthouse DownREIT L.P. [Member]
Consolidation And Basis Of Presentation (Textual) [Abstract]
Operating Partnership outstanding units					16,229,407	0	0
General Partners Capital Account Units Owned Percentage		50.10%
Limited Partner [Member]
Consolidation And Basis Of Presentation (Textual) [Abstract]
OP units outstanding related to limited partner					7,301,628	7,413,802	7,567,253	7,643,548
Limited Partner [Member] | UDR Lighthouse DownREIT L.P. [Member]
Consolidation And Basis Of Presentation (Textual) [Abstract]
Operating Partnership outstanding units					16,137,973
Percentage of units outstanding owned by limited partners		49.90%

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General Partners Capital Account Units Owned Percentage.

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Investment Building and Building Improvements, and Furniture, Fixtures and Equipment

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Joint venture number of apartment homes in operating communities.

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Number Of Apartment Homes Owned And Consolidated By Company

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Number of Markets Operating Within

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 5
-Subparagraph (SAB TOPIC 4.F)
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187171-122770

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-Publisher FASB
-Name Accounting Standards Codification
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The number of each class of partnership units outstanding at the balance sheet date. Units represent shares of ownership of the general, limited, and preferred partners.

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-Name Accounting Standards Codification
-Topic 946
-SubTopic 210
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