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Debt (UNITED DOMINION REALTY, L.P.) (Details Textual) - USD ($) |  |  | 3 Months Ended | 6 Months Ended |
--- | --- | --- | --- | --- | ---
Jun. 27, 2014 | Sep. 26, 2013 | Jun. 30, 2015 | Jun. 30, 2015 | Dec. 31, 2014
Debt Instrument [Line Items] |  |  |  |  |
Borrowings outstanding |  |  | $ 2,300,000 | $ 2,300,000 | $ 1,900,000
Weighted average interest rate |  |  | 3.58% |  |
Unamortized fair market adjustment |  |  | $ 5,700,000 | 5,700,000 | 6,700,000
UDR Bank Credit Facility [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Total revolving credit facility |  |  | 900,000,000 | 900,000,000 | 900,000,000
Fixed Rate Debt [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Secured debt including debt on real estate held for sale |  |  | $ 975,024,000 | 975,024,000 | 969,296,000
Weighted average interest rate |  |  | 5.28% |  |
Variable Rate Debt [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Secured debt including debt on real estate held for sale |  |  | $ 375,415,000 | 375,415,000 | 392,233,000
Weighted average interest rate |  |  | 1.45% |  |
Fannie Mae [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Borrowings outstanding |  |  | $ 815,666,000 | $ 815,666,000 | 834,282,000
Fannie Mae credit facilities [Member] | Fixed Rate Debt [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Debt Instrument, Maturity Date Range, Start |  |  |  | May 01, 2017 |
Debt Instrument, Maturity Date Range, End |  |  |  | Jul. 01, 2023 |
Debt, Weighted Average Interest Rate |  |  | 5.12% | 5.12% |
Fannie Mae credit facilities [Member] | Variable Rate Debt [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Debt Instrument, Interest Rate at Period End |  |  | 1.63% | 1.63% |
Mortgages [Member] | Fixed Rate Debt [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Debt Instrument, Maturity Date Range, Start |  |  |  | Dec. 09, 2015 |
Weighted average interest rate |  |  | 5.50% |  |
Notes payable minimum interest rates range |  |  |  | 3.43% |
Notes payable maximum interest rates range |  |  |  | 6.16% |
Debt Instrument, Maturity Date Range, End |  |  |  | May 01, 2019 |
Mortgages [Member] | Variable Rate Debt [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Weighted average interest rate |  |  | 1.94% |  |
Tax Exempt Notes Payable [Member] | Variable Rate Debt [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Weighted average interest rate |  |  | 0.84% |  |
Unsecured Revolving Credit Facility due October 2015 [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Borrowings outstanding |  |  | $ 457,000,000 | $ 457,000,000 | 152,500,000
Weighted average interest rate |  |  | 1.12% |  |
2.90% Term Notes due January 2016 [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Weighted average interest rate |  |  |  | 1.70% |
Five Point Two Five Percent, Medium Term Notes, Due January 2016 [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Weighted average interest rate |  |  |  | 5.25% |
4.25% Medium-Term Notes due June 2018 [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Weighted average interest rate |  |  |  | 4.25% |
Unamortized fair market adjustment |  |  | $ 1,251,000 | $ 1,251,000 | 1,465,000
Three point seven percent medium term note due October 2020 [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Unamortized fair market adjustment |  |  | $ 42,000 | $ 42,000 | 46,000
ThreePointSevenTermNotesDueOctober2020 [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Weighted average interest rate |  |  |  | 3.70% |
Debt Instrument, Maturity Date |  | Oct. 31, 2020 |  |  |
4.63% Medium-Term Notes due January 2022 [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Weighted average interest rate |  |  | 4.63% |  |
Unamortized fair market adjustment |  |  | $ 2,344,000 | $ 2,344,000 | 2,523,000
3.75 MTN Due July 2024 [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Weighted average interest rate |  |  | 3.75% |  |
Unamortized fair market adjustment |  |  | $ 938,000 | 938,000 | 990,000
Debt Instrument, Maturity Date | Jul. 01, 2024 |  |  |  |
United Dominion Reality L.P. [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Debt Instrument, Unamortized Premium |  |  | 4,200,000 | 4,200,000 | 6,200,000
Secured debt including debt on real estate held for sale |  |  | 912,567,000 | $ 912,567,000 | 931,959,000
Weighted average interest rate |  |  |  | 4.43% |
United Dominion Reality L.P. [Member] | Fixed Rate Debt [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Secured debt including debt on real estate held for sale |  |  | 708,058,000 | $ 708,058,000 | 712,199,000
Weighted average interest rate |  |  |  | 5.21% |
United Dominion Reality L.P. [Member] | Variable Rate Debt [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Secured debt including debt on real estate held for sale |  |  | 204,509,000 | $ 204,509,000 | 219,760,000
Weighted average interest rate |  |  |  | 1.74% |
United Dominion Reality L.P. [Member] | Fannie Mae [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Borrowings outstanding |  |  | 511,511,000 | $ 511,511,000 | 526,588,000
United Dominion Reality L.P. [Member] | Fannie Mae credit facilities [Member] | Fixed Rate Debt [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Weighted average interest rate |  |  |  | 4.90% |
United Dominion Reality L.P. [Member] | Fannie Mae credit facilities [Member] | Variable Rate Debt [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Weighted average interest rate |  |  |  | 1.88% |
United Dominion Reality L.P. [Member] | Mortgages [Member] | Fixed Rate Debt [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Secured debt including debt on real estate held for sale |  |  | 374,056,000 | $ 374,056,000 | 378,371,000
Weighted average interest rate |  |  |  | 5.49% |
Notes payable maximum interest rates range |  |  |  | 5.94% |
United Dominion Reality L.P. [Member] | Tax Exempt Notes Payable [Member] | Variable Rate Debt [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Secured debt including debt on real estate held for sale |  |  | 27,000,000 | $ 27,000,000 | 27,000,000
Weighted average interest rate |  |  |  | 0.85% |
Debt Instrument, Maturity Date Range, End |  |  |  | Mar. 01, 2032 |
United Dominion Reality L.P. [Member] | 2.90% Term Notes due January 2016 [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Debt Instrument, Maturity Date Range, End |  |  |  | Jun. 01, 2018 |
United Dominion Reality L.P. [Member] | 2.90% Term Notes due January 2016 [Member] | Financial Guarantee [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Guarantor borrowing capacity |  |  | 250,000,000 | $ 250,000,000 |
United Dominion Reality L.P. [Member] | 1.68% Term Notes due December 2016 [Member] | Financial Guarantee [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Guarantor borrowing capacity |  |  | 100,000,000 | $ 100,000,000 |
United Dominion Reality L.P. [Member] | Five Point Two Five Percent, Medium Term Notes, Due January 2016 [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Debt Instrument, Maturity Date Range, End |  |  |  | Jun. 01, 2018 |
United Dominion Reality L.P. [Member] | 4.25% Medium-Term Notes due June 2018 [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Debt Instrument, Maturity Date Range, End |  |  |  | Jun. 01, 2018 |
United Dominion Reality L.P. [Member] | 4.25% Medium-Term Notes due June 2018 [Member] | Financial Guarantee [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Guarantor borrowing capacity |  |  | 300,000,000 | $ 300,000,000 |
United Dominion Reality L.P. [Member] | Three point seven percent medium term note due October 2020 [Member] | Financial Guarantee [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Guarantor borrowing capacity |  |  | 300,000,000 | $ 300,000,000 |
United Dominion Reality L.P. [Member] | 4.63% Medium-Term Notes due January 2022 [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Debt Instrument, Maturity Date Range, End |  |  |  | Jan. 01, 2022 |
United Dominion Reality L.P. [Member] | 4.63% Medium-Term Notes due January 2022 [Member] | Financial Guarantee [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Guarantor borrowing capacity |  |  | 400,000,000 | $ 400,000,000 |
United Dominion Reality L.P. [Member] | 3.75 MTN Due July 2024 [Member] | Financial Guarantee [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Guarantor borrowing capacity |  |  | 300,000,000 | 300,000,000 |
Mortgages [Member] | Fair Value, Measurements, Recurring [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member] | Mortgages [Member] | Fixed Rate Debt [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Secured debt including debt on real estate held for sale |  |  | 408,736,000 | 408,736,000 | 401,210,000
Mortgages [Member] | Fair Value, Measurements, Recurring [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member] | Mortgages [Member] | Variable Rate Debt [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Secured debt including debt on real estate held for sale |  |  | 31,337,000 | 31,337,000 | 31,337,000
Mortgages [Member] | Fair Value, Measurements, Recurring [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member] | United Dominion Reality L.P. [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Fixed Rate Secured Debt Instruments Fair Value |  |  | 374,056,000 | 374,056,000 | 378,371,000
Fannie Mae credit facilities [Member] | Fair Value, Measurements, Recurring [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member] | Fannie Mae credit facilities [Member] | Fixed Rate Debt [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Secured debt including debt on real estate held for sale |  |  | 566,288,000 | 566,288,000 | 568,086,000
Fannie Mae credit facilities [Member] | Fair Value, Measurements, Recurring [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member] | Fannie Mae credit facilities [Member] | Variable Rate Debt [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Secured debt including debt on real estate held for sale |  |  | 249,378,000 | 249,378,000 | 266,196,000
Fannie Mae credit facilities [Member] | Fair Value, Measurements, Recurring [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member] | United Dominion Reality L.P. [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Variable Rate Secured Debt Instruments Fair Value |  |  | 177,509,000 | 177,509,000 | 192,760,000
Fixed Rate Secured Debt Instruments Fair Value |  |  | 334,002,000 | 334,002,000 | 333,828,000
Fannie Mae credit facilities [Member] | Fair Value, Measurements, Recurring [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member] | United Dominion Reality L.P. [Member] | Fannie Mae credit facilities [Member] | Fixed Rate Debt [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Secured debt including debt on real estate held for sale |  |  | 334,002,000 | 334,002,000 | 333,828,000
Fannie Mae credit facilities [Member] | Fair Value, Measurements, Recurring [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member] | United Dominion Reality L.P. [Member] | Fannie Mae credit facilities [Member] | Variable Rate Debt [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Secured debt including debt on real estate held for sale |  |  | $ 177,509,000 | $ 177,509,000 | $ 192,760,000

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- Definition The average effective interest rate during the reporting period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28551-108399 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(1)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 22 -Article 5 + Details
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