Debt (UNITED DOMINION REALTY, L.P.) (Details 2) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Debt Instrument [Line Items]
2013	$ 6,639
2014	359,562
2015	750,080
2016	568,925
2017	243,374
Thereafter	1,466,143
Total	1,385,034	1,430,135
United Dominion Reality L.P. [Member]
Debt Instrument [Line Items]
2013	4,347
2014	8,903
2015	193,274
2016	132,338
2017	23,890
Thereafter	576,396
Total	939,148	967,239
United Dominion Reality L.P. [Member] \| Mortgages Notes Payable [Member] \| Fixed Rate Debt [Member]
Debt Instrument [Line Items]
2013	4,183
2014	8,559
2015	192,910
2016	131,956
2017	1,640
Thereafter	51,675
Total	390,923
United Dominion Reality L.P. [Member] \| Fannie Mae credit facilities [Member] \| Fixed Rate Debt [Member]
Debt Instrument [Line Items]
2013	164
2014	344
2015	364
2016	382
2017	15,684
Thereafter	362,229
Total	379,167
United Dominion Reality L.P. [Member] \| Fannie Mae credit facilities [Member] \| Variable Rate Debt [Member]
Debt Instrument [Line Items]
2013	0
2014	0
2015	0
2016	0
2017	6,566
Thereafter	135,492
Total	142,058
United Dominion Reality L.P. [Member] \| Tax Exempt Notes Payable [Member] \| Variable Rate Debt [Member]
Debt Instrument [Line Items]
2013	0
2014	0
2015	0
2016	0
2017	0
Thereafter	27,000
Total	$ 27,000

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Amount of long-term debt, sinking fund requirements, and other securities redeemable at fixed or determinable prices and dates maturing after the fifth fiscal year following the latest fiscal year.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 470

-SubTopic 10

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6802200&loc=d3e1835-112601

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 47

-Paragraph 10

-Subparagraph b

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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- Definition

Amount of long-term debt, sinking fund requirements, and other securities redeemable at fixed or determinable prices and dates maturing in the next fiscal year following the latest fiscal year.

+ References

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Amount of long-term debt, sinking fund requirements, and other securities redeemable at fixed or determinable prices and dates maturing in the fifth fiscal year following the latest fiscal year.

+ References

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Amount of long-term debt, sinking fund requirements, and other securities redeemable at fixed or determinable prices and dates maturing in the fourth fiscal year following the latest fiscal year.

+ References

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Amount of long-term debt, sinking fund requirements, and other securities redeemable at fixed or determinable prices and dates maturing in the third fiscal year following the latest fiscal year.

+ References

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Amount of long-term debt, sinking fund requirements, and other securities redeemable at fixed or determinable prices and dates maturing in the second fiscal year following the latest fiscal year.

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- Definition

Carrying value as of the balance sheet date, including the current and noncurrent portions, of collateralized debt obligations (with maturities initially due after one year or beyond the operating cycle, if longer). Such obligations include mortgage loans, chattel loans, and any other borrowings secured by assets of the borrower.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.7-03.16)

-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.16)

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 16

-Article 9

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 20, 22

-Article 5

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