Hurricane Related (Recoveries)/Charges (UNITED DOMINION REALTY, L.P.) (Details) (USD $)	3 Months Ended		6 Months Ended		3 Months Ended	6 Months Ended	12 Months Ended	3 Months Ended		6 Months Ended		3 Months Ended	6 Months Ended		6 Months Ended	12 Months Ended	3 Months Ended		6 Months Ended	12 Months Ended	6 Months Ended	12 Months Ended	6 Months Ended	12 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	4 Months Ended	6 Months Ended	4 Months Ended	6 Months Ended	4 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013 New York Properties [Member]	Jun. 30, 2013 New York Properties [Member]	Dec. 31, 2012 New York Properties [Member] Apartment_Homes	Jun. 30, 2013 United Dominion Reality L.P. [Member]	Jun. 30, 2012 United Dominion Reality L.P. [Member]	Jun. 30, 2013 United Dominion Reality L.P. [Member]	Jun. 30, 2012 United Dominion Reality L.P. [Member]	Jun. 30, 2013 United Dominion Reality L.P. [Member] New York Properties [Member]	Jun. 30, 2013 United Dominion Reality L.P. [Member] New York Properties [Member]	Dec. 31, 2012 United Dominion Reality L.P. [Member] New York Properties [Member] Communities Apartment_Homes	Jun. 30, 2013 Hurricane Sandy [Member]	Dec. 31, 2012 Hurricane Sandy [Member]	Jun. 30, 2013 Hurricane Sandy [Member] United Dominion Reality L.P. [Member]	Dec. 31, 2012 Hurricane Sandy [Member] United Dominion Reality L.P. [Member]	Jun. 30, 2013 Hurricane Sandy [Member] United Dominion Reality L.P. [Member]	Dec. 31, 2012 Hurricane Sandy [Member] United Dominion Reality L.P. [Member]	Jun. 30, 2012 Hurricane Sandy [Member] Rent Concessions [Member]	Dec. 31, 2012 Hurricane Sandy [Member] Rent Concessions [Member] United Dominion Reality L.P. [Member]	Jun. 30, 2012 Hurricane Sandy [Member] Rent not contractually receivable [Member]	Dec. 31, 2012 Hurricane Sandy [Member] Rent not contractually receivable [Member] United Dominion Reality L.P. [Member]	Jun. 30, 2013 Business Interruption [Member] Hurricane Sandy [Member]	Jun. 30, 2013 Business Interruption [Member] Hurricane Sandy [Member]	Jun. 30, 2013 Business Interruption [Member] Hurricane Sandy [Member] United Dominion Reality L.P. [Member]	Apr. 30, 2013 Business Interruption [Member] Hurricane Sandy [Member] United Dominion Reality L.P. [Member]	Jun. 30, 2013 FY 2012 [Member] Business Interruption [Member] Hurricane Sandy [Member]	Apr. 30, 2013 FY 2012 [Member] Business Interruption [Member] Hurricane Sandy [Member] United Dominion Reality L.P. [Member]	Jun. 30, 2013 FY 2013 [Member] Business Interruption [Member] Hurricane Sandy [Member]	Apr. 30, 2013 FY 2013 [Member] Business Interruption [Member] Hurricane Sandy [Member] United Dominion Reality L.P. [Member]
Number of Communities Owned							3							2
Number of Apartments Owned							1,706							1,001
Impairment of Long-Lived Assets Held-for-use					$ 0	$ 0	$ 9,000,000					$ 0	$ 0				$ 0	$ 7,100,000	$ 0
Other Cost and Expense, Operating	1,807,000	1,434,000	3,450,000	2,817,000			10,400,000	1,423,000	1,305,000	2,809,000	2,623,000							7,000,000
Business Interruption Costs																4,400,000				2,200,000	3,600,000	1,800,000	800,000	400,000
Total Estimated Insurance Recovery															14,500,000					10,800,000
Insurance Recoveries	(2,772,000)	0	(5,793,000)	0				(2,257,000)	0	(4,276,000)	0						2,300,000
Proceeds from Insurance Settlement, Operating Activities																									$ 500,000	$ 3,000,000	$ 500,000	$ 2,000,000	$ 2,800,000	$ 1,800,000	$ 187,000	$ 200,000