Secured and Unsecured Debt (Details Textual 1) (USD $)	1 Months Ended	3 Months Ended	6 Months Ended		1 Months Ended	3 Months Ended	1 Months Ended	3 Months Ended	12 Months Ended										1 Months Ended			12 Months Ended	3 Months Ended		3 Months Ended		3 Months Ended
	Jun. 30, 2013	Jun. 30, 2013	Jun. 30, 2013	Dec. 31, 2011	Jun. 30, 2013 OneHundredMillionUnsecuredTermLoanDueJune2018 [Member]	Jun. 30, 2013 OneHundredMillionUnsecuredTermLoanDueJune2018 [Member]	Jun. 30, 2013 TwoHundredFiftyMillionUnsecuredTermLoanDueJune2018 [Member]	Jun. 30, 2013 TwoHundredFiftyMillionUnsecuredTermLoanDueJune2018 [Member]	Dec. 31, 2012 1.67% Term Notes due December 2016 [Member]	Jun. 30, 2013 1.67% Term Notes due December 2016 [Member]	Jun. 30, 2012 1.67% Term Notes due December 2016 [Member]	Jun. 30, 2013 2.90% Term Notes due January 2016 [Member]	Dec. 31, 2012 2.90% Term Notes due January 2016 [Member]	Jun. 30, 2012 2.90% Term Notes due January 2016 [Member]	Jun. 30, 2013 4.63% Medium-Term Notes due January 2022 [Member]	Dec. 31, 2012 4.63% Medium-Term Notes due January 2022 [Member]	Jun. 30, 2013 2.68% Term Notes due December 2016 [Member]	Dec. 31, 2012 2.68% Term Notes due December 2016 [Member]	Jun. 30, 2013 UDR Bank Credit Facility [Member]	Jun. 06, 2013 UDR Bank Credit Facility [Member]	Dec. 31, 2012 UDR Bank Credit Facility [Member]	Dec. 31, 2012 Beginning of range of initial term of debt [Member] Line of Credit [Member]	Jun. 30, 2013 Fannie Mae credit facility subject to refinancing [Member]	Jun. 06, 2013 Fannie Mae credit facility subject to refinancing [Member]	Jun. 30, 2013 Fannie Mae credit facility, Seven Year Fixed [Member]	Jun. 06, 2013 Fannie Mae credit facility, Seven Year Fixed [Member]	Jun. 30, 2013 Fannie Mae credit facility, Ten Year Variable [Member]	Jun. 06, 2013 Fannie Mae credit facility, Ten Year Variable [Member]
Unsecured Debt (Textual) [Abstract]
Total revolving credit facility																			$ 900,000,000		$ 900,000,000
Initial term of credit facilities (in years)		10 years	10 years																			7 years
Additional time period for extending facilities (in years)																			6 months
Increase in maximum borrowing capacity of unsecured revolving credit facility																				1,450,000,000.00
Credit facility interest rate	110
Line of Credit Facility, Commitment Fee Description	20
Fixed interest rate										1.45%	1.65%	2.73%		2.90%	4.63%	4.63%	2.50%	2.68%							0.00%
Interest rate																			1.30%		1.40%
Line of credit	2,100,000	2,100,000	2,100,000	3,900,000
Debt Instrument, Maturity Date					Jun. 30, 2018		Jun. 30, 2018		Jun. 06, 2018										Dec. 31, 2017				Dec. 31, 2019
Senior Notes	250,000,000	250,000,000	250,000,000		100,000,000	100,000,000			35,000,000	35,000,000		250,000,000	250,000,000		396,939,000	396,759,000	65,000,000	65,000,000
Debt Instrument, Description of Variable Rate Basis					125	142.5	125	142.5															284				190
Amount of refinanced credit facilities																								$ 186,000,000		$ 90,000,000		$ 96,000,000
Initial term of debt																									7 years		10 years