Capital Structure (UNITED DOMINION REALTY, L.P.) (Details)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Limited Partners' Capital Account [Line Items]
Limited Partners' Capital Account, Units Redeemed		(1,002,556)
Partners' Capital Account, Units, Acquisitions		(1,002,556)
Balance	183,278,698	184,281,254	184,281,254
Partners' Capital Account, Units, Redeemed	0	0	0
OP Units issued for acquisitions of real estate			0
Balance	183,278,698	183,278,698	184,281,254
UDR, Inc.
Limited Partners' Capital Account [Line Items]
Balance	174,002,342	173,848,891
Class A Limited Partner
Limited Partners' Capital Account [Line Items]
Balance	1,751,671
Limited Partner
Limited Partners' Capital Account [Line Items]
Partners' Capital Account, Units, Acquisitions		0
Balance	7,567,253	7,643,548	7,669,632
Partners' Capital Account, Units, Redeemed	(153,451)	(76,295)	(20,438)
OP Units issued for acquisitions of real estate			(5,646)
Balance	7,413,802	7,567,253	7,643,548
Limited Partner | UDR, Inc.
Limited Partners' Capital Account [Line Items]
Limited Partners' Capital Account, Units Redeemed		1,002,556
Partners' Capital Account, Units, Acquisitions		(1,002,556)
Balance	173,848,891	174,775,152	174,749,068
Partners' Capital Account, Units, Redeemed	153,451	76,295	20,438
OP Units issued for acquisitions of real estate			5,646
Balance	174,002,342	173,848,891	174,775,152
Limited Partner | Class A Limited Partner
Limited Partners' Capital Account [Line Items]
Partners' Capital Account, Units, Acquisitions		0
Balance	1,751,671	1,751,671	1,751,671
Partners' Capital Account, Units, Redeemed	0	0	0
OP Units issued for acquisitions of real estate			0
Balance	1,751,671	1,751,671	1,751,671
General Partner | UDR, Inc.
Limited Partners' Capital Account [Line Items]
Partners' Capital Account, Units, Acquisitions		0
Balance	110,883	110,883	110,883
Partners' Capital Account, Units, Redeemed	0	0	0
OP Units issued for acquisitions of real estate			0
Balance	110,883	110,883	110,883