Derivatives and Hedging Activity (UNITED DOMINION REALTY, L.P.) (Details 3) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013		Dec. 31, 2012
Offsetting Derivative Assets [Abstract]
Gross Amounts of Recognized Assets	$ 1		$ 2
Gross Amounts Offset in the Consolidated Balance Sheets	0		0
Net Amounts of Assets Presented in the Consolidated Balance Sheets	1	[1]	2	[1]
Gross Amounts Not Offset in the Consolidated Balance Sheets, Financial Instruments	0		0
Gross Amounts Not Offset in the Consolidated Balance Sheets, Cash Collateral Received	0		0
Net Amount	1		2
Offsetting Derivative Liabilities [Abstract]
Gross Amounts of Recognized Liabilities	7,560		11,022
Gross Amounts Offset in the Consolidated Balance Sheets	0		0
Net Amounts of Liabilities Presented in the Consolidated Balance Sheets	7,560	[2]	11,022	[2]
Gross Amounts Not Offset in the Consolidated Balance Sheets, Financial Instruments	0		0
Gross Amounts Not Offset in the Consolidated Balance Sheets, Cash Collateral Received	0		0
Net Amount	7,560		11,022
United Dominion Reality L.P. [Member]
Offsetting Derivative Assets [Abstract]
Gross Amounts of Recognized Assets	1		2
Gross Amounts Offset in the Consolidated Balance Sheets	0		0
Net Amounts of Assets Presented in the Consolidated Balance Sheets	1	[1]	2	[1]
Gross Amounts Not Offset in the Consolidated Balance Sheets, Financial Instruments	0		0
Gross Amounts Not Offset in the Consolidated Balance Sheets, Cash Collateral Received	0		0
Net Amount	1		2
Offsetting Derivative Liabilities [Abstract]
Gross Amounts of Recognized Liabilities	3,490		4,750
Gross Amounts Offset in the Consolidated Balance Sheets	0		0
Net Amounts of Liabilities Presented in the Consolidated Balance Sheets	3,490	[2]	4,750	[2]
Gross Amounts Not Offset in the Consolidated Balance Sheets, Financial Instruments	0		0
Gross Amounts Not Offset in the Consolidated Balance Sheets, Cash Collateral Received	0		0
Net Amount	$ 3,490		$ 4,750

[1] Amounts reconcile to the aggregate fair value of derivative assets in the "Tabular Disclosure of Fair Values of Derivative Instruments on the Balance Sheet" located in this footnote.

[2] Amounts reconcile to the aggregate fair value of derivative liabilities in the "Tabular Disclosure of Fair Values of Derivative Instruments on the Balance Sheet" located in this footnote.