Derivatives and Hedging Activity (UNITED DOMINION REALTY, L.P.) (Details Textual) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012
Entity Information [Line Items]
Cash flow hedge ineffectiveness in earnings materiality	less than a  $1,000	less than a  $1,000	less than a  $1,000	less than a  $1,000
Estimated additional accumulated other comprehensive Income/(Loss) transferred to interest expense	$ 5,600,000		$ 5,600,000
Losses in the fair value of derivatives not designated in hedging relationships	3,000	7,000	5,000	(291,000)
Fair value of derivatives in a net liability position	8,000,000		8,000,000
Payment required to pay for contract termination	8,000,000		8,000,000
Derivative, Collateral, Obligation to Return Cash	0		0		0
United Dominion Reality L.P. [Member]
Entity Information [Line Items]
Cash flow hedge ineffectiveness in earnings materiality	less than a $1,000 loss	less than a $1,000 loss	less than a $1,000 loss	less than a $1,000 loss
Estimated additional accumulated other comprehensive Income/(Loss) transferred to interest expense	2,300,000		2,300,000
Losses in the fair value of derivatives not designated in hedging relationships	3,000	5,000	5,000	7,000
Fair value of derivatives in a net liability position	3,600,000		3,600,000
Payment required to pay for contract termination	3,600,000		3,600,000
Derivative, Collateral, Obligation to Return Cash	$ 0		$ 0		$ 0