Real Estate Owned (Details Textual) (USD $)	1 Months Ended	3 Months Ended		6 Months Ended
	Apr. 30, 2011	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010	Apr. 05, 2011	Mar. 31, 2011
Purchase price allocation of UDR's real estate community acquisitions
Total purchase price of assets acquired		$ 628,300,000		$ 628,300,000
Real Estate Owned (Textuals) [Abstract]
Company's owned property details				170 communities in 11 states plus the District of Columbia totaling 48,556 apartment homes.
Fair value of OP units							$ 24.47
Exchange of assets by the Company						500,000,000
Acquisition cost		2,100,000		2,724,000
Interest capitalized during period		3,500,000	3,300,000	6,100,000	7,300,000
Revenues of acquiree since acquisition date				10,800,000
Earnings of acquiree since acquisition date				6,700,000
Multifamily apartment communities sold by UDR	2
Number of homes in multifamily apartment communities of UDR	434
Number of homes in multifamily apartment communities of operating partnership	984
Multifamily apartment communities sold by operating partnership	4
10 Hanover Square [Member]
Purchase price allocation of UDR's real estate community acquisitions
Acquisition cost of company							259,800,000
Assumption of debt in acquisition							192,000,000
Fair value of debt assumed							208,100,000
Number of OP Units issued in partial consideration of acquisition of property	2,569,606
Deemed value of Operating partnership units	equal to the greater of $25.00 or the closing price per share of the Company’s common stock for the 10 day period ended on (and including) the date one business day prior to the settlement date (and including) the date one business day prior to the settlement date
Basis of determining value of OP Units issued in partial consideration of acqusition of property	$25.00 or the closing price per share of the Company's common stock for the 10 day period ended on (and including) the date of one business day prior to settlement date.
Per Unit Fair Value of OP Units Issued in partial consideration of acqusition of property							$ 24.47
Asset Exchange [Member]
Purchase price allocation of UDR's real estate community acquisitions
Acquisition cost of company						263,000,000
Assumption of debt in acquisition						55,800,000
Fair value of debt assumed						61,700,000
Cash paid in asset exchange						28,100,000
Land [Member]
Purchase price allocation of UDR's real estate community acquisitions
Total purchase price of assets acquired		114,500,000		114,500,000
Building and improvements [Member]
Purchase price allocation of UDR's real estate community acquisitions
Total purchase price of assets acquired		506,800,000		506,800,000
Furniture, fixtures and equipment [Member]
Purchase price allocation of UDR's real estate community acquisitions
Total purchase price of assets acquired		3,400,000		3,400,000
Intangible Assets [Member]
Purchase price allocation of UDR's real estate community acquisitions
Total purchase price of assets acquired		25,400,000		25,400,000
Intangible Liabilities [Member]
Purchase price allocation of UDR's real estate community acquisitions
Total purchase price of assets acquired		$ 23,200,000		$ 23,200,000