Real Estate Owned( Details 1) (USD $) In Thousands, unless otherwise specified	6 Months Ended
Jun. 30, 2011
UDR's real estate community acquisitions
Units	1,738
Purchase Price	$ 628,288
10 Hanover Square [Member] \| New York, NY [Member]
UDR's real estate community acquisitions
Acquisition Date	2011-04-01
Units	493
Purchase Price	259,750
388 Beale [Member] \| San Francisco, CA [Member]
UDR's real estate community acquisitions
Acquisition Date	2011-04-01
Units	227
Purchase Price	90,500
14 North [Member] \| Boston, MA [Member]
UDR's real estate community acquisitions
Acquisition Date	2011-04-01
Units	387
Purchase Price	64,500
Inwood West [Member] \| Boston, MA [Member]
UDR's real estate community acquisitions
Acquisition Date	2011-04-01
Units	446
Purchase Price	108,000
View 14 [Member] \| Metropolitan D.C. [Member]
UDR's real estate community acquisitions
Acquisition Date	2011-06-01
Units	185
Purchase Price	$ 105,538

Month, date and year in which the acquirer obtains control of the acquiree.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 25
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=6909708&loc=d3e848-128460

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6909870&loc=d3e1392-128463

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 141R
-Paragraph 3
-Subparagraph c
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 25
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=6909708&loc=d3e845-128460

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 141R
-Paragraph 10, 11
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 141R
-Paragraph 68
-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 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Acquisition Date
-URI http://asc.fasb.org/extlink&oid=6919109

+ Details