Income from Participating Loan

No definition available.

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- Definition

Participating Loan, Interest Rate, Stated Percentage

+ References

No definition available.

+ Details

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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Participating Loan Years to Maturity

+ References

No definition available.

+ Details

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Data Type:	xbrli:durationItemType
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- Definition

Amount of gain on the sale of property that does not qualify for gain recognition as of the balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 605
-SubTopic 40
-Section S99
-Paragraph 1
-Subparagraph (SAB TOPIC 5.U.Q2)
-URI http://asc.fasb.org/extlink&oid=6955272&loc=d3e221323-122791

+ Details

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Balance Type:	credit
Period Type:	instant

- Definition

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=6382943&loc=d3e33918-111571

+ Details

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Balance Type:	na
Period Type:	instant

- Definition

This item represents the carrying amount on the entity's balance sheet of its investment in common stock of an equity method investee. This is not an indicator of the fair value of the investment, rather it is the initial cost adjusted for the entity's share of earnings and losses of the investee, adjusted for any distributions (dividends) and other than temporary impairment (OTTI) losses recognized.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=35755396&loc=d3e33749-111570

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 210.5-02.12)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_EquityMethodInvestments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The number of real estate properties owned as of the balance sheet date.

+ References

No definition available.

+ Details

Name:	us-gaap_NumberOfRealEstateProperties
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

The number of units in a real estate property owned as of the balance sheet date.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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Period Type:	duration

- Details

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- Details

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- Details

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- Details

Name:	us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis=udr_DevelopmentCommunityMember
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- Details

Name:	us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis=us-gaap_LandMember
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- Details

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- Details

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- Details

Name:	us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=udr_PreferredEquityInvestmentWestCoastDevelopmentJVMember
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Joint Ventures (Details) $ in Thousands	12 Months Ended
Joint Ventures (Details) $ in Thousands	Dec. 31, 2015 USD ($) Communities	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)	Dec. 31, 2015	Dec. 31, 2015 USD ($)
Schedule of Equity Method Investments [Line Items]
Number of Real Estate Properties	133			2
Investment in and advances to unconsolidated joint ventures, net		$ 718,226			$ 938,906
Deferred Gain on Sale of Property		24,700			6,800
MetLife I
Schedule of Equity Method Investments [Line Items]
Investment in and advances to unconsolidated joint ventures, net		13,306			15,894
MetLife I \| Operating Community [Member]
Schedule of Equity Method Investments [Line Items]
Number of Real Estate Properties				4
Number of Units in Real Estate Property				0
Investment in and advances to unconsolidated joint ventures, net		$ 13,306			15,894
Equity method investment, ownership percent		15.70%		17.20%
MetLife II
Schedule of Equity Method Investments [Line Items]
Investment in and advances to unconsolidated joint ventures, net		$ 431,277			425,230
MetLife II \| Operating Community [Member]
Schedule of Equity Method Investments [Line Items]
Number of Real Estate Properties				21
Number of Units in Real Estate Property				4,642
Investment in and advances to unconsolidated joint ventures, net		$ 431,277			425,230
Equity method investment, ownership percent		50.00%		50.00%
Unconsolidated Joint Venture Other MetLife [Member]
Schedule of Equity Method Investments [Line Items]
Investment in and advances to unconsolidated joint ventures, net		$ 197,646			407,102
Unconsolidated Joint Venture Other MetLife [Member] \| Operating Community [Member]
Schedule of Equity Method Investments [Line Items]
Number of Real Estate Properties				1
Number of Units in Real Estate Property				1,437
Investment in and advances to unconsolidated joint ventures, net		$ 134,939			171,659
Equity method investment, ownership percent		50.60%		50.60%
Unconsolidated Joint Venture Other MetLife [Member] \| Development Community [Member]
Schedule of Equity Method Investments [Line Items]
Number of Real Estate Properties				4
Unconsolidated Joint Venture Other MetLife [Member] \| Land Parcel
Schedule of Equity Method Investments [Line Items]
Number of Real Estate Properties				1
Unconsolidated Joint Venture Vitruvian Park [Member]
Schedule of Equity Method Investments [Line Items]
Investment in and advances to unconsolidated joint ventures, net		$ 80,302			73,469
Unconsolidated Joint Venture Vitruvian Park [Member] \| Operating Community [Member]
Schedule of Equity Method Investments [Line Items]
Number of Real Estate Properties				3
Number of Units in Real Estate Property				1,130
Investment in and advances to unconsolidated joint ventures, net		$ 80,302			73,469
Equity method investment, ownership percent		50.00%		50.00%
Unconsolidated Joint Venture Vitruvian Park [Member] \| Land Parcel [Member]
Schedule of Equity Method Investments [Line Items]
Number of Real Estate Properties				6
KFH
Schedule of Equity Method Investments [Line Items]
Investment in and advances to unconsolidated joint ventures, net		$ 21,596			17,211
KFH \| Operating Community [Member]
Schedule of Equity Method Investments [Line Items]
Number of Real Estate Properties				3
Number of Units in Real Estate Property				660
Investment in and advances to unconsolidated joint ventures, net		$ 21,596			17,211
Equity method investment, ownership percent		30.00%		30.00%
Texas JV
Schedule of Equity Method Investments [Line Items]
Investment in and advances to unconsolidated joint ventures, net		$ (25,901)			0
Deferred Gain on Sale of Property					24,200
Texas JV \| Operating Community [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percent		20.00%		0.00%
Texas JV \| Development Community [Member]
Schedule of Equity Method Investments [Line Items]
Number of Real Estate Properties				0
Number of Units in Real Estate Property				0
Investment in and advances to unconsolidated joint ventures, net		$ (25,901)			0
Unconsolidated Joint Ventures [Member]
Schedule of Equity Method Investments [Line Items]
Investment in and advances to unconsolidated joint ventures, net		655,519			703,463
Participating Loan Investment Steele Creek Denver Colorado [Member] \| Development Community [Member]
Schedule of Equity Method Investments [Line Items]
Investment in and advances to unconsolidated joint ventures, net		62,707			90,747
Participating Loan, Interest Rate, Stated Percentage				6.50%
Participating Loan Years to Maturity	1 year 7 months 6 days
Income from Participating Loan	$ 5,453	2,350	$ 156
Preferred Equity Investment West Coast Development JV [Member] \| Development Community [Member]
Schedule of Equity Method Investments [Line Items]
Investment in and advances to unconsolidated joint ventures, net		0			$ 144,696
Participating Loan, Interest Rate, Stated Percentage				6.50%
Participating Loan Years to Maturity	0 months
Income from Participating Loan	$ 3,692	$ 0	$ 0