Equity Method Investment Summarized Financial Information Accounts payable and accrued liabilities

No definition available.

Name:	udr_EquityMethodInvestmentSummarizedFinancialInformationAccountspayableandaccruedliabilities
Namespace Prefix:	udr_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The amount due to UDR by an equity method investment of the entity.

+ References

No definition available.

+ Details

Name:	udr_EquityMethodInvestmentSummarizedFinancialInformationAmountDueToRelatedParty
Namespace Prefix:	udr_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	udr_EquityMethodInvestmentSummarizedFinancialInformationBalanceSheetsAbstract
Namespace Prefix:	udr_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Equity Method Investment Summarized Financial Information Cash and cash equivalents

+ References

No definition available.

+ Details

Name:	udr_EquityMethodInvestmentSummarizedFinancialInformationCashandcashequivalents
Namespace Prefix:	udr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The amount of depreciation and amortization reported by an equity method investment of the entity.

+ References

No definition available.

+ Details

Name:	udr_EquityMethodInvestmentSummarizedFinancialInformationDepreciationAmortization
Namespace Prefix:	udr_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Equity Method Investment, Summarized Financial Information, Gain (Loss) on Sale of Real Estate

+ References

No definition available.

+ Details

Name:	udr_EquityMethodInvestmentSummarizedFinancialInformationGainLossonSaleofRealEstate
Namespace Prefix:	udr_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Equity Method Investment Summarized Financial Information Income/(loss) from discontinued operations

+ References

No definition available.

+ Details

Name:	udr_EquityMethodInvestmentSummarizedFinancialInformationIncomelossfromdiscontinuedoperations
Namespace Prefix:	udr_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Equity Method Investment Summarized Financial Information Interest expense

+ References

No definition available.

+ Details

Name:	udr_EquityMethodInvestmentSummarizedFinancialInformationInterestexpense
Namespace Prefix:	udr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Equity Method Investment Summarized Financial Information Other assets

+ References

No definition available.

+ Details

Name:	udr_EquityMethodInvestmentSummarizedFinancialInformationOtherassets
Namespace Prefix:	udr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Equity Method Investment Summarized Financial Information Other income/(expense)

+ References

No definition available.

+ Details

Name:	udr_EquityMethodInvestmentSummarizedFinancialInformationOtherincomeexpense
Namespace Prefix:	udr_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Equity Method Investment Summarized Financial Information Property Operating Expense

+ References

No definition available.

+ Details

Name:	udr_EquityMethodInvestmentSummarizedFinancialInformationPropertyOperatingExpense
Namespace Prefix:	udr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The amount of net real estate assets reported by an equity method investment of the entity.

+ References

No definition available.

+ Details

Name:	udr_EquityMethodInvestmentSummarizedFinancialInformationRealEstateNet
Namespace Prefix:	udr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Equity Method of Investment Summarized Financial Information Operating income/(loss)

+ References

No definition available.

+ Details

Name:	udr_EquityMethodofInvestmentSummarizedFinancialInformationOperatingincomeloss
Namespace Prefix:	udr_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Income from Participating Loan

+ References

No definition available.

+ Details

Name:	udr_IncomefromParticipatingLoan
Namespace Prefix:	udr_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Participating Loan, Interest Rate, Stated Percentage

+ References

No definition available.

+ Details

Name:	udr_ParticipatingLoanInterestRateStatedPercentage
Namespace Prefix:	udr_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Participating Loan Years to Maturity

+ References

No definition available.

+ Details

Name:	udr_ParticipatingLoanYearstoMaturity
Namespace Prefix:	udr_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- 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

Name:	us-gaap_DeferredGainOnSaleOfProperty
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
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

Name:	us-gaap_EquityMethodInvestmentOwnershipPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
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 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.12)

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

Reference 2: 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

+ Details

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

- Definition

The amount of assets reported by an equity method investment of the entity.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 235

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.4-08.(g))

-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 323

-SubTopic 10

-Section 50

-Paragraph 3

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=6382943&loc=d3e33918-111571

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 323

-SubTopic 10

-Section 50

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6382943&loc=d3e33912-111571

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 28

-Subparagraph (f)

-URI http://asc.fasb.org/extlink&oid=6957238&loc=d3e14064-108612

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph bb

-Article 1

Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 08

-Paragraph g

-Subparagraph 1, 2

-Article 4

Reference 7: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph w

-Article 1

+ Details

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

- Definition

Amount of equity, including noncontrolling interest, reported by an equity method investment of the entity.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 28

-URI http://asc.fasb.org/extlink&oid=6957238&loc=d3e14064-108612

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 323

-SubTopic 10

-Section 50

-Paragraph 3

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=6382943&loc=d3e33918-111571

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 28

-Subparagraph (f)

-URI http://asc.fasb.org/extlink&oid=6957238&loc=d3e14064-108612

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 235

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.4-08.g)

-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

+ Details

Name:	us-gaap_EquityMethodInvestmentSummarizedFinancialInformationEquity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	us-gaap_EquityMethodInvestmentSummarizedFinancialInformationIncomeStatementAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The amount of liabilities reported by an equity method investment of the entity.

+ References

+ Details

Name:	us-gaap_EquityMethodInvestmentSummarizedFinancialInformationLiabilities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The amount of liabilities and equity reported by an equity method investment of the entity.

+ References

+ Details

Name:	us-gaap_EquityMethodInvestmentSummarizedFinancialInformationLiabilitiesAndEquity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The amount of net income (loss) reported by an equity method investment of the entity.

+ References

+ Details

Name:	us-gaap_EquityMethodInvestmentSummarizedFinancialInformationNetIncomeLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The amount of noncurrent liabilities reported by an equity method investment of the entity.

+ References

+ Details

Name:	us-gaap_EquityMethodInvestmentSummarizedFinancialInformationNoncurrentLiabilities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The amount of revenue from sale of goods and services reduced by sales returns, allowances, and discounts reported by an equity method investment of the entity.

+ References

No definition available.

+ Details

Name:	us-gaap_EquityMethodInvestmentSummarizedFinancialInformationRevenue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

This item represents the entity's proportionate share for the period of the net income (loss) of its investee (such as unconsolidated subsidiaries and joint ventures) to which the equity method of accounting is applied. This item includes income or expense related to stock-based compensation based on the investor's grant of stock to employees of an equity method investee.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 9

-Article 5

Reference 3: 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 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.12)

-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Paragraph 11

-Article 7

+ Details

Name:	us-gaap_IncomeLossFromEquityMethodInvestments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- 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

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

- Details

Name:	us-gaap_ScheduleOfEquityMethodInvestmentsLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Joint Ventures (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended		12 Months Ended		3 Months Ended		9 Months Ended	12 Months Ended																	3 Months Ended	9 Months Ended
	Sep. 30, 2014 Communities	Sep. 30, 2013	Sep. 30, 2014 Communities	Sep. 30, 2013	Dec. 31, 2012	Dec. 31, 2013	Sep. 30, 2014 Unconsolidated Joint Ventures [Member]	Sep. 30, 2013 Unconsolidated Joint Ventures [Member]	Sep. 30, 2014 Unconsolidated Joint Ventures [Member]	Dec. 31, 2013 Unconsolidated Joint Ventures [Member]	Dec. 31, 2012 Unconsolidated Joint Ventures [Member]	Dec. 31, 2013 Unconsolidated Joint Venture Two Stoughton Massachusetts [Member]	Sep. 30, 2014 Operating Community [Member] Unconsolidated Joint Venture UDR Met Life I Partnership [Member] Apartment_Homes Communities	Mar. 31, 2014 Operating Community [Member] Unconsolidated Joint Venture UDR Met Life I Partnership [Member] Communities	Dec. 31, 2013 Operating Community [Member] Unconsolidated Joint Venture UDR Met Life I Partnership [Member]	Sep. 30, 2014 Operating Community [Member] Unconsolidated Joint Venture UDR MetLife II Partnership [Member] Communities Apartment_Homes	Dec. 31, 2013 Operating Community [Member] Unconsolidated Joint Venture UDR MetLife II Partnership [Member]	Sep. 30, 2014 Operating Community [Member] Unconsolidated Joint Venture Vitruvian Park [Member] Apartment_Homes	Dec. 31, 2013 Operating Community [Member] Unconsolidated Joint Venture Vitruvian Park [Member]	Sep. 30, 2014 Operating Community [Member] Unconsolidated Joint Venture Three [Member] Apartment_Homes Communities	Dec. 31, 2013 Operating Community [Member] Unconsolidated Joint Venture Three [Member]	Sep. 30, 2014 Operating Community [Member] Unconsolidated Joint Venture Four Texas [Member] Apartment_Homes Communities	Dec. 31, 2013 Operating Community [Member] Unconsolidated Joint Venture Four Texas [Member]	Sep. 30, 2014 Development Community [Member] Unconsolidated Joint Venture Vitruvian Park [Member] Apartment_Homes Communities	Sep. 30, 2014 Development Community [Member] Unconsolidated Joint Venture Other MetLife [Member] Apartment_Homes Communities	Dec. 31, 2013 Development Community [Member] Unconsolidated Joint Venture Other MetLife [Member]	Sep. 30, 2014 Development Community [Member] Participating Loan Investment Steele Creek Denver Colorado [Member]	Sep. 30, 2014 Development Community [Member] Participating Loan Investment Steele Creek Denver Colorado [Member]	Sep. 30, 2013 Development Community [Member] Participating Loan Investment Steele Creek Denver Colorado [Member]	Dec. 31, 2013 Development Community [Member] Participating Loan Investment Steele Creek Denver Colorado [Member]	Sep. 30, 2014 Land [Member] Unconsolidated Joint Venture UDR Met Life I Partnership [Member] Land_Parcels	Dec. 31, 2013 Land [Member] Unconsolidated Joint Venture UDR Met Life I Partnership [Member]	Sep. 30, 2014 Land [Member] Unconsolidated Joint Venture UDR MetLife II Partnership [Member] Land_Parcels	Sep. 30, 2014 Land [Member] Unconsolidated Joint Venture Vitruvian Park [Member]	Sep. 30, 2014 Land [Member] Unconsolidated Joint Venture Other MetLife [Member] Communities
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Summarized Financial Information, Gain (Loss) on Sale of Real Estate							$ (113)	$ 0	$ (25,492)
Equity Method Investment Summarized Financial Information Income/(loss) from discontinued operations							0	(806)	14	(22,592)
Financial information relating to unconsolidated joint ventures operations
Total revenues							63,449	61,198	187,340		166,796
Equity Method Investment Summarized Financial Information Property Operating Expense							(24,769)	(24,509)	(74,324)	(64,532)
Real estate depreciation and amortization							(24,525)	(21,285)	(73,727)		(58,699)
Net income /(loss)							(4,837)	(4,772)	(43,124)		(32,305)
UDR income/(loss) from unconsolidated entities	(939)	(3,794)	(4,932)	(6,081)	(6,081)
Combined summary of balance sheets relating to unconsolidated joint ventures
Total real estate, net							3,012,380		3,012,380	3,124,178
Equity Method Investment Summarized Financial Information Cash and cash equivalents							40,656		40,656	41,792
Equity Method Investment Summarized Financial Information Other assets							37,903		37,903	32,234
Total assets							3,090,939		3,090,939	3,198,204
Amount due to UDR							10,856		10,856	12,187
Third party debt							1,659,316		1,659,316	1,722,960
Equity Method Investment Summarized Financial Information Accounts payable and accrued liabilities							49,388		49,388	41,562
Total liabilities							1,719,560		1,719,560	1,776,709
Total equity							1,371,379		1,371,379	1,421,495
Equity Method Investment, Summarized Financial Information, Liabilities and Equity							3,090,939		3,090,939	3,198,204
Investment in and advances to unconsolidated joint ventures, net	650,441		650,441			507,655	606,619		606,619	493,382			0		40,336	436,805	327,926	79,807	79,318	22,891	25,919	(25,624)	(23,591)		87,376	36,313	43,822	43,822		14,273	5,364	7,161
Income from Participating Loan																											1	1,419	0
Deferred gains on the sale of depreciable property	27,132		27,132			25,400
Ownership percentage, equity method investment												95.00%	0.00%		13.20%	50.00%	50.00%	50.00%	50.00%	30.00%	30.00%	20.00%	20.00%		51.00%	51.00%					4.00%	4.00%	50.10%		4.00%
Number of apartment homes													0			4,642		739		660		3,359		391	828
Joint Venture and Partnership Number of Operating Communities Owned	141		141										0	6		21				3		8		1	2,000						5		2	6	1,000
Participating Loan, Interest Rate, Stated Percentage																											6.50%	6.50%
Participating Loan Years to Maturity																												3 years 1 month 2 days
Equity Method of Investment Summarized Financial Information Operating income/(loss)							14,155	15,404	39,289	43,565
Equity Method Investment Summarized Financial Information Interest expense							(18,879)	(19,370)	(56,745)	(53,282)
Equity Method Investment Summarized Financial Information Other income/(expense)							$ 0	$ 0	$ (190)	$ 4