Fair Value of Derivatives and Financial Instruments (UNITED DOMINION REALTY, L.P.) (Details) (Fair Value, Measurements, Recurring [Member], USD $) In Thousands, unless otherwise specified	Jun. 30, 2013		Dec. 31, 2012		Jun. 30, 2012
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis
Total assets	$ 67,619
Secured debt instruments - variable rate
Total liabilities	3,536,211				3,654,305
Interest Rate Contracts [Member]
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis
Derivatives - Interest rate contracts	1	[1]
Derivatives - Interest rate contracts	7,560	[1]			11,022	[1]
Mortgages Notes Payable [Member]
Secured debt instruments - fixed rate
Secured debt instruments - fixed rate	471,742	[2]			494,728	[2]
Secured debt instruments - variable rate
Secured debt instruments - variable rate					37,415	[2]
Tax Exempt Notes Payable [Member]
Secured debt instruments - variable rate
Secured debt instruments - variable rate	94,700	[2]			94,700	[2]
Line of Credit [Member]
Secured debt instruments - fixed rate
Secured debt instruments - fixed rate	658,532	[2]			689,295	[2]
Secured debt instruments - variable rate
Secured debt instruments - variable rate	211,409	[2]			211,409	[2]
Level 1 [Member]
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis
Total assets	0
Secured debt instruments - variable rate
Total liabilities	0				0
Level 2 [Member]
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis
Total assets	1
Secured debt instruments - variable rate
Total liabilities	7,560				11,022
Level 3 [Member]
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis
Total assets	67,618
Secured debt instruments - variable rate
Total liabilities	3,528,651				3,643,283
United Dominion Reality L.P. [Member]
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis
Total assets	1		2
Secured debt instruments - variable rate
Total liabilities	975,081		1,035,714
United Dominion Reality L.P. [Member] | Interest Rate Contracts [Member]
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis
Derivatives - Interest rate contracts	1	[3]	2	[3]
Derivatives - Interest rate contracts	3,490	[3]	4,750	[3]
United Dominion Reality L.P. [Member] | Mortgages Notes Payable [Member]
Secured debt instruments - fixed rate
Secured debt instruments - fixed rate	409,771	[4]	429,973	[4]
Secured debt instruments - variable rate
Secured debt instruments - variable rate			37,415	[4]
United Dominion Reality L.P. [Member] | Tax Exempt Notes Payable [Member]
Secured debt instruments - variable rate
Secured debt instruments - variable rate	27,000	[4]	27,000	[4]
United Dominion Reality L.P. [Member] | Line of Credit [Member]
Secured debt instruments - fixed rate
Secured debt instruments - fixed rate	392,762	[4]	399,389	[4]
Secured debt instruments - variable rate
Secured debt instruments - variable rate	142,058	[4]	137,187	[4]
United Dominion Reality L.P. [Member] | Level 1 [Member]
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis
Total assets	0		0
Secured debt instruments - variable rate
Total liabilities	0		0
United Dominion Reality L.P. [Member] | Level 2 [Member]
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis
Total assets	1		2
Secured debt instruments - variable rate
Total liabilities	3,490		4,750
United Dominion Reality L.P. [Member] | Level 3 [Member]
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis
Total assets	0		0
Secured debt instruments - variable rate
Total liabilities	971,591		1,030,964
Estimate of Fair Value, Fair Value Disclosure [Member]
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis
Total assets			64,932
Estimate of Fair Value, Fair Value Disclosure [Member] | Interest Rate Contracts [Member]
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis
Derivatives - Interest rate contracts			2
Estimate of Fair Value, Fair Value Disclosure [Member] | Level 1 [Member]
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis
Total assets			0
Estimate of Fair Value, Fair Value Disclosure [Member] | Level 1 [Member] | Interest Rate Contracts [Member]
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis
Derivatives - Interest rate contracts	0		0
Derivatives - Interest rate contracts	0				0
Estimate of Fair Value, Fair Value Disclosure [Member] | Level 1 [Member] | Mortgages Notes Payable [Member]
Secured debt instruments - fixed rate
Secured debt instruments - fixed rate	0				0
Secured debt instruments - variable rate
Secured debt instruments - variable rate					0
Estimate of Fair Value, Fair Value Disclosure [Member] | Level 1 [Member] | Tax Exempt Notes Payable [Member]
Secured debt instruments - variable rate
Secured debt instruments - variable rate	0				0
Estimate of Fair Value, Fair Value Disclosure [Member] | Level 1 [Member] | Line of Credit [Member]
Secured debt instruments - fixed rate
Secured debt instruments - fixed rate	0				0
Secured debt instruments - variable rate
Secured debt instruments - variable rate	0				0
Estimate of Fair Value, Fair Value Disclosure [Member] | Level 2 [Member]
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis
Total assets			2
Estimate of Fair Value, Fair Value Disclosure [Member] | Level 2 [Member] | Interest Rate Contracts [Member]
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis
Derivatives - Interest rate contracts	1		2
Derivatives - Interest rate contracts	7,560
Estimate of Fair Value, Fair Value Disclosure [Member] | Level 2 [Member] | Mortgages Notes Payable [Member]
Secured debt instruments - fixed rate
Secured debt instruments - fixed rate	0				0
Secured debt instruments - variable rate
Secured debt instruments - variable rate					0
Estimate of Fair Value, Fair Value Disclosure [Member] | Level 2 [Member] | Tax Exempt Notes Payable [Member]
Secured debt instruments - variable rate
Secured debt instruments - variable rate	0				0
Estimate of Fair Value, Fair Value Disclosure [Member] | Level 2 [Member] | Line of Credit [Member]
Secured debt instruments - fixed rate
Secured debt instruments - fixed rate	0				0
Secured debt instruments - variable rate
Secured debt instruments - variable rate	0				0
Estimate of Fair Value, Fair Value Disclosure [Member] | Level 3 [Member]
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis
Total assets			64,930
Estimate of Fair Value, Fair Value Disclosure [Member] | Level 3 [Member] | Interest Rate Contracts [Member]
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis
Derivatives - Interest rate contracts	0		0
Derivatives - Interest rate contracts	0				0
Estimate of Fair Value, Fair Value Disclosure [Member] | Level 3 [Member] | Mortgages Notes Payable [Member]
Secured debt instruments - fixed rate
Secured debt instruments - fixed rate	471,742				494,728
Secured debt instruments - variable rate
Secured debt instruments - variable rate					37,415
Estimate of Fair Value, Fair Value Disclosure [Member] | Level 3 [Member] | Tax Exempt Notes Payable [Member]
Secured debt instruments - variable rate
Secured debt instruments - variable rate	94,700				94,700
Estimate of Fair Value, Fair Value Disclosure [Member] | Level 3 [Member] | Line of Credit [Member]
Secured debt instruments - fixed rate
Secured debt instruments - fixed rate	658,532				689,295
Secured debt instruments - variable rate
Secured debt instruments - variable rate	211,409				211,409
Estimate of Fair Value, Fair Value Disclosure [Member] | United Dominion Reality L.P. [Member] | Level 1 [Member] | Interest Rate Contracts [Member]
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis
Derivatives - Interest rate contracts	0		0
Derivatives - Interest rate contracts	0		0
Estimate of Fair Value, Fair Value Disclosure [Member] | United Dominion Reality L.P. [Member] | Level 1 [Member] | Mortgages Notes Payable [Member]
Secured debt instruments - fixed rate
Secured debt instruments - fixed rate	0		0
Secured debt instruments - variable rate
Secured debt instruments - variable rate			0
Estimate of Fair Value, Fair Value Disclosure [Member] | United Dominion Reality L.P. [Member] | Level 1 [Member] | Tax Exempt Notes Payable [Member]
Secured debt instruments - variable rate
Secured debt instruments - variable rate	0		0
Estimate of Fair Value, Fair Value Disclosure [Member] | United Dominion Reality L.P. [Member] | Level 1 [Member] | Line of Credit [Member]
Secured debt instruments - fixed rate
Secured debt instruments - fixed rate	0		0
Secured debt instruments - variable rate
Secured debt instruments - variable rate	0		0
Estimate of Fair Value, Fair Value Disclosure [Member] | United Dominion Reality L.P. [Member] | Level 2 [Member] | Interest Rate Contracts [Member]
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis
Derivatives - Interest rate contracts	1		2
Derivatives - Interest rate contracts	3,490		4,750
Estimate of Fair Value, Fair Value Disclosure [Member] | United Dominion Reality L.P. [Member] | Level 2 [Member] | Mortgages Notes Payable [Member]
Secured debt instruments - fixed rate
Secured debt instruments - fixed rate	0		0
Secured debt instruments - variable rate
Secured debt instruments - variable rate			0
Estimate of Fair Value, Fair Value Disclosure [Member] | United Dominion Reality L.P. [Member] | Level 2 [Member] | Tax Exempt Notes Payable [Member]
Secured debt instruments - variable rate
Secured debt instruments - variable rate	0		0
Estimate of Fair Value, Fair Value Disclosure [Member] | United Dominion Reality L.P. [Member] | Level 2 [Member] | Line of Credit [Member]
Secured debt instruments - fixed rate
Secured debt instruments - fixed rate	0		0
Secured debt instruments - variable rate
Secured debt instruments - variable rate	0		0
Estimate of Fair Value, Fair Value Disclosure [Member] | United Dominion Reality L.P. [Member] | Level 3 [Member] | Interest Rate Contracts [Member]
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis
Derivatives - Interest rate contracts	0		0
Derivatives - Interest rate contracts	0		0
Estimate of Fair Value, Fair Value Disclosure [Member] | United Dominion Reality L.P. [Member] | Level 3 [Member] | Mortgages Notes Payable [Member]
Secured debt instruments - fixed rate
Secured debt instruments - fixed rate	409,771		429,973
Secured debt instruments - variable rate
Secured debt instruments - variable rate			37,415
Estimate of Fair Value, Fair Value Disclosure [Member] | United Dominion Reality L.P. [Member] | Level 3 [Member] | Tax Exempt Notes Payable [Member]
Secured debt instruments - variable rate
Secured debt instruments - variable rate	27,000		27,000
Estimate of Fair Value, Fair Value Disclosure [Member] | United Dominion Reality L.P. [Member] | Level 3 [Member] | Line of Credit [Member]
Secured debt instruments - fixed rate
Secured debt instruments - fixed rate	392,762		399,389
Secured debt instruments - variable rate
Secured debt instruments - variable rate	142,058		137,187
Carrying (Reported) Amount, Fair Value Disclosure [Member]
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis
Total assets	66,701		64,008
Secured debt instruments - variable rate
Total liabilities	3,402,283		3,420,355
Carrying (Reported) Amount, Fair Value Disclosure [Member] | Interest Rate Contracts [Member]
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis
Derivatives - Interest rate contracts			2
Derivatives - Interest rate contracts	7,560		11,022
Carrying (Reported) Amount, Fair Value Disclosure [Member] | Mortgages Notes Payable [Member]
Secured debt instruments - fixed rate
Secured debt instruments - fixed rate	450,641		455,533
Secured debt instruments - variable rate
Secured debt instruments - variable rate			37,415
Carrying (Reported) Amount, Fair Value Disclosure [Member] | Tax Exempt Notes Payable [Member]
Secured debt instruments - variable rate
Secured debt instruments - variable rate	94,700		94,700
Carrying (Reported) Amount, Fair Value Disclosure [Member] | Line of Credit [Member]
Secured debt instruments - fixed rate
Secured debt instruments - fixed rate	628,284		631,078
Secured debt instruments - variable rate
Secured debt instruments - variable rate	211,409		211,409
Carrying (Reported) Amount, Fair Value Disclosure [Member] | United Dominion Reality L.P. [Member]
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis
Total assets	1		2
Secured debt instruments - variable rate
Total liabilities	942,638		971,989
Carrying (Reported) Amount, Fair Value Disclosure [Member] | United Dominion Reality L.P. [Member] | Interest Rate Contracts [Member]
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis
Derivatives - Interest rate contracts			2
Derivatives - Interest rate contracts	3,490		4,750
Carrying (Reported) Amount, Fair Value Disclosure [Member] | United Dominion Reality L.P. [Member] | Mortgages Notes Payable [Member]
Secured debt instruments - fixed rate
Secured debt instruments - fixed rate	390,923		394,999
Secured debt instruments - variable rate
Secured debt instruments - variable rate			37,415
Carrying (Reported) Amount, Fair Value Disclosure [Member] | United Dominion Reality L.P. [Member] | Tax Exempt Notes Payable [Member]
Secured debt instruments - variable rate
Secured debt instruments - variable rate	27,000		27,000
Carrying (Reported) Amount, Fair Value Disclosure [Member] | United Dominion Reality L.P. [Member] | Line of Credit [Member]
Secured debt instruments - fixed rate
Secured debt instruments - fixed rate	379,167		370,638
Secured debt instruments - variable rate
Secured debt instruments - variable rate	$ 142,058		$ 137,187

[1] See Note 6, Secured and Unsecured Debt

[2] See Note 2, Significant Accounting Policies

[3] See Note 5, Debt

[4] See Note 8, Derivatives and Hedging Activity