UDR (UDR) 10-Q 29 Oct 14 2014 Q3 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	9 Months Ended
	Sep. 30, 2014	Oct. 27, 2014
Entity Registrant Name	'UDR, Inc.	'
Entity Central Index Key	'0000074208	'
Document Type	'10-Q	'
Document Period End Date	30-Sep-14	'
Amendment Flag	'false	'
Document Fiscal Year Focus	'2014	'
Document Fiscal Period Focus	'Q3	'
Current Fiscal Year End Date	'--12-31	'
Entity Well-known Seasoned Issuer	'Yes	'
Entity Voluntary Filers	'No	'
Entity Current Reporting Status	'Yes	'
Entity Filer Category	'Large Accelerated Filer	'
Entity Common Stock, Shares Outstanding	'	255,217,903
United Dominion Reality L.P. [Member]	'	'
Entity Registrant Name	'United Dominion Realty L.P.	'
Entity Central Index Key	'0001018254	'
Document Type	'10-Q	'
Document Period End Date	30-Sep-14	'
Amendment Flag	'false	'
Document Fiscal Year Focus	'2014	'
Document Fiscal Period Focus	'Q3	'
Current Fiscal Year End Date	'--12-31	'
Entity Well-known Seasoned Issuer	'No	'
Entity Voluntary Filers	'No	'
Entity Current Reporting Status	'Yes	'
Entity Filer Category	'Non-accelerated Filer	'
Entity Common Stock, Shares Outstanding	'	0

Consolidated_Balance_Sheets

Consolidated Balance Sheets (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Real estate owned:	'	'
Real estate held for investment	$8,106,684	$7,723,844
Less: accumulated depreciation	-2,378,520	-2,200,815
Real estate held for investment, net	5,728,164	5,523,029
Real estate under development (net of accumulated depreciation of $513 and $1,411, respectively)	321,094	466,002
Real estate held for disposition (net of accumulated depreciation $0 and $6,568, respectively)	0	10,152
Total real estate owned, net of accumulated depreciation	6,049,258	5,999,183
Cash and cash equivalents	14,605	30,249
Restricted cash	23,969	22,796
Deferred financing costs, net	24,344	26,924
Notes receivable, net	18,318	83,033
Investment in and advances to unconsolidated joint ventures, net	650,441	507,655
Other assets	117,153	137,882
Total assets	6,898,088	6,807,722
Liabilities:	'	'
Secured debt	1,399,372	1,442,077
Unsecured debt	2,228,820	2,081,626
Real estate taxes payable	29,403	13,847
Accrued interest payable	27,131	32,279
Security deposits and prepaid rent	32,710	27,203
Distributions payable	69,487	61,907
Accounts payable, accrued expenses, and other liabilities	82,233	118,682
Total liabilities	3,869,156	3,777,621
Commitments and contingencies (Note 12)	'	'
Redeemable noncontrolling interests in the Operating Partnership	249,814	217,597
Equity:	'	'
Common stock, $0.01 par value; 350,000,000 shares authorized; 255,215,905 and 250,749,665 shares issued and outstanding at September 30, 2014 and December 31, 2013, respectively	2,552	2,507
Additional paid-in capital	4,223,893	4,109,765
Distributions in excess of net income	-1,493,890	-1,342,070
Accumulated other comprehensive income/(loss), net	-866	-5,125
Total stockholders' equity	2,778,260	2,811,648
Noncontrolling interests	858	856
Total equity	2,779,118	2,812,504
Total liabilities and equity	6,898,088	6,807,722
8.00% Series E Cumulative Convertible Preferred Stock	'	'
Equity:	'	'
8.00% Series E Cumulative Convertible; 2,803,812 shares and outstanding at September 30, 2014 and December 31, 2013	$46,571	$46,571

Consolidated_Balance_Sheets_Pa

Consolidated Balance Sheets (Parenthetical) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, except Share data, unless otherwise specified
Real estate owned:	'	'
Real estate under development accumulated depreciation	$513	$1,411
Accumulated depreciation of real estate held for disposition	$0	$6,568
Equity:	'	'
Preferred stock, par or stated value per share	$0	$0
Preferred stock, shares authorized	50,000,000	50,000,000
Common stock, par value	$0.01	$0.01
Common stock, shares authorized	350,000,000	350,000,000
Common stock, shares issued	255,215,905	250,749,665
Common stock, shares outstanding	255,215,905	250,749,665
8.00% Series E Cumulative Convertible Preferred Stock	'	'
Equity:	'	'
Preferred stock, shares issued	2,803,812	2,803,812
Preferred stock, shares outstanding	2,803,812	2,803,812

Consolidated_Balance_Sheets_UN

Consolidated Balance Sheets (UNITED DOMINION REALTY, L.P) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Real estate owned:	'	'
Real estate held for investment	$8,106,684	$7,723,844
Less: accumulated depreciation	-2,378,520	-2,200,815
Real estate held for investment, net	5,728,164	5,523,029
Real estate under development (net of accumulated depreciation of $513 and $0, respectively)	321,094	466,002
Total real estate owned, net of accumulated depreciation	6,049,258	5,999,183
Cash and cash equivalents	14,605	30,249
Restricted cash	23,969	22,796
Deferred financing costs, net	24,344	26,924
Other assets	117,153	137,882
Total assets	6,898,088	6,807,722
LIABILITIES AND CAPITAL	'	'
Secured debt	1,399,372	1,442,077
Real estate taxes payable	29,403	13,847
Accrued interest payable	27,131	32,279
Security deposits and prepaid rent	32,710	27,203
Distributions payable	69,487	61,907
Deferred gains on the sale of depreciable property	27,132	25,400
Accounts payable, accrued expenses, and other liabilities	82,233	118,682
Total liabilities	3,869,156	3,777,621
Commitments and contingencies (Note 11)	'	'
Partners' Capital:	'	'
Accumulated other comprehensive income/(loss), net	-866	-5,125
Total liabilities and equity	6,898,088	6,807,722
United Dominion Reality L.P. [Member]	'	'
Real estate owned:	'	'
Real estate held for investment	4,099,395	4,108,417
Less: accumulated depreciation	-1,357,610	-1,241,574
Real estate held for investment, net	2,741,785	2,866,843
Real estate under development (net of accumulated depreciation of $513 and $0, respectively)	119,315	80,063
Total real estate owned, net of accumulated depreciation	2,861,100	2,946,906
Cash and cash equivalents	1,484	1,897
Restricted cash	13,989	13,526
Deferred financing costs, net	4,783	5,848
Other assets	25,070	25,064
Total assets	2,906,426	2,993,241
LIABILITIES AND CAPITAL	'	'
Secured debt	928,273	934,865
Notes payable due to General Partner	88,696	88,696
Real estate taxes payable	13,433	6,228
Accrued interest payable	3,195	3,323
Security deposits and prepaid rent	17,331	14,172
Distributions payable	47,788	43,253
Deferred gains on the sale of depreciable property	47,531	63,838
Accounts payable, accrued expenses, and other liabilities	23,850	35,769
Total liabilities	1,170,097	1,190,144
Commitments and contingencies (Note 11)	'	'
Partners' Capital:	'	'
General partner: 110,883 OP Units outstanding at September 30, 2014 and December 31, 2013	1,114	1,163
Limited partners: 183,167,815 OP Units outstanding at September 30, 2014 and December 31, 2013	1,718,119	1,797,836
Accumulated other comprehensive income/(loss), net	-1,475	-3,065
Total partners' capital	1,717,758	1,795,934
Payable/(receivable) due to/(from) General Partner	795	-9,916
Noncontrolling interests	17,776	17,079
Total capital	1,736,329	1,803,097
Total liabilities and equity	$2,906,426	$2,993,241

Consolidated_Balance_Sheets_UN1

Consolidated Balance Sheets (UNITED DOMINION REALTY, L.P) (Parenthetical) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, except Share data, unless otherwise specified
Real estate under development accumulated depreciation	$513	$1,411
Partners' Capital:	'	'
OP units outstanding related to general partner	174,111,227	'
United Dominion Reality L.P. [Member]	'	'
Real estate under development accumulated depreciation	$0	$0
Partners' Capital:	'	'
OP units outstanding related to general partner	110,883	110,883
OP units outstanding related to limited partner	183,167,815	183,167,815

Consolidated_Statements_of_Ope

Consolidated Statements of Operations (Unaudited) (USD $)	3 Months Ended		9 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
REVENUES	'	'	'	'
Rental income	$203,587	$187,917	$598,898	$556,163
Joint venture management and other fees	3,165	3,207	9,599	9,347
Total revenues	206,752	191,124	608,497	565,510
OPERATING EXPENSES	'	'	'	'
Property operating and maintenance	39,086	36,686	112,646	107,660
Real estate taxes and insurance	24,697	24,080	73,844	70,288
Property management	5,598	5,168	16,470	15,295
Other operating expenses	2,009	1,775	6,097	5,211
Real estate depreciation and amortization	89,339	83,738	266,748	251,231
General and administrative expense	11,554	11,364	36,078	30,706
Casualty-related (recoveries)/charges, net	0	-6,460	500	-12,253
Other depreciation and amortization	1,385	1,176	3,658	3,460
Total operating expenses	173,668	157,527	516,041	471,598
Operating income	33,084	33,597	92,456	93,912
Income/(loss) from unconsolidated entities	-939	-3,794	-4,932	-6,081
Interest expense	-33,087	-30,939	-97,662	-92,723
Interest and other income/(expense), net	9,061	829	11,902	3,291
Income/(loss) before income taxes and discountinued operations	8,119	-307	1,764	-1,601
Tax benefit/(expense), net	2,492	2,658	8,011	7,314
Income/(loss) from continuing operations	10,611	2,351	9,775	5,713
Income/(loss) from discontinued operations, net of tax	79	884	10	2,567
Income/(loss) before gain/(loss) of real estate owned	10,690	3,235	9,785	8,280
Gains/(loss) on sales of real estate, net of tax	31,302	0	82,305	0
Net income/(loss)	41,992	3,235	92,090	8,280
Net (income)/loss attributable to redeemable noncontrolling interests in the Operating Partnership	-1,447	-84	-3,171	-198
Net (income)/loss attributable to noncontrolling interests	4	37	-2	30
Net income/(loss) attributable to UDR, Inc.	40,549	3,188	88,917	8,112
Net (loss)/income attributable to common stockholders	39,618	2,257	86,124	5,319
Earnings per weighted average common share - basic and diluted:	'	'	'	'
Income/(loss) from continuing operations attributable to common stockholders, per basic share	$0.16	$0.01	$0.34	$0.01
Income/(loss) from discontinued operations attributable to common stockholders, per basic share	$0	$0	$0	$0.01
Net income/(loss) attributable to common stockholders	$0.16	$0.01	$0.34	$0.02
Income/(loss) from continuing operations attributable to common stockholders, per diluted share	$0.16	$0.01	$0.34	$0.01
Income from discontinued operations attributable to common stockholders, per diluted share	$0	$0	$0	$0.01
Net income/(loss) attributable to common stockholders	$0.16	$0.01	$0.34	$0.02
Common distributions declared per share	$0.26	$0.24	$0.78	$0.71
Weighted average number of common shares outstanding b basic	251,655	249,985	250,701	249,962
Weighted average number of common shares outstanding b diluted	253,732	251,454	252,675	251,439
Series E Preferred Stock [Member]	'	'	'	'
OPERATING EXPENSES	'	'	'	'
Distributions to preferred stockholders - Series E (Convertible)	($931)	($931)	($2,793)	($2,793)

Consolidated_Statements_of_Ope1

Consolidated Statements of Operations (Unaudited) (UNITED DOMINION REALTY, L.P) (USD $)	3 Months Ended		9 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
REVENUES	'	'	'	'
Rental income	$203,587	$187,917	$598,898	$556,163
OPERATING EXPENSES	'	'	'	'
Property operating and maintenance	39,086	36,686	112,646	107,660
Real estate taxes and insurance	24,697	24,080	73,844	70,288
Property management	5,598	5,168	16,470	15,295
Other operating expenses	2,009	1,775	6,097	5,211
Real estate depreciation and amortization	89,339	83,738	266,748	251,231
General and administrative	11,554	11,364	36,078	30,706
Casualty-related (recoveries)/charges, net	0	-6,460	500	-12,253
Total operating expenses	173,668	157,527	516,041	471,598
Operating income	33,084	33,597	92,456	93,912
Interest expense on note payable due to General Partner	-1,200	-3,500	-300	-800
Interest and other income/(expense), net	9,061	829	11,902	3,291
Income/(loss) from continuing operations	10,611	2,351	9,775	5,713
Income/(loss) from discontinued operations, net of tax	79	884	10	2,567
Gains/(loss) on sales of real estate owned	31,302	0	82,305	0
Net income/(loss)	41,992	3,235	92,090	8,280
Net (income)/loss attributable to noncontrolling interests	-1,500	-92	-3,336	-364
Net (income)/loss attributable to noncontrolling interests	4	37	-2	30
Net income/(loss) attributable to OP unitholders	40,549	3,188	88,917	8,112
United Dominion Reality L.P. [Member]	'	'	'	'
REVENUES	'	'	'	'
Rental income	107,444	101,559	314,656	299,750
OPERATING EXPENSES	'	'	'	'
Property operating and maintenance	19,906	19,339	56,468	55,952
Real estate taxes and insurance	11,785	11,796	35,050	33,774
Property management	2,955	2,793	8,653	8,243
Other operating expenses	1,484	1,405	4,371	4,215
Real estate depreciation and amortization	45,043	44,333	134,011	133,962
General and administrative	6,939	6,855	21,368	18,324
Casualty-related (recoveries)/charges, net	0	-3,807	500	-8,083
Total operating expenses	88,112	82,714	260,421	246,387
Operating income	19,332	18,845	54,235	53,363
Interest expense	-9,306	-8,506	-27,176	-26,284
Interest expense on note payable due to General Partner	-1,151	-267	-3,453	-801
Income/(loss) from continuing operations	8,875	10,072	23,606	26,278
Income/(loss) from discontinued operations, net of tax	0	978	0	2,766
Income/(loss) before gain/(loss) of real estate owned	8,875	11,050	23,606	29,044
Gains/(loss) on sales of real estate owned	0	0	40,687	0
Net income/(loss)	8,875	11,050	64,293	29,044
Net (income)/loss attributable to noncontrolling interests	-238	-39	-697	-151
Net income/(loss) attributable to OP unitholders	$8,637	$11,011	$63,596	$28,893
Income/(loss) per OP unit- basic and diluted:	'	'	'	'
Income/(loss) from continuing operations attributable to OP unitholders (in dollars per share)	$0.05	$0.05	$0.35	$0.14
Income/(loss) from discontinued operations (in dollars per share)	$0	$0.01	$0	$0.02
Net income/(loss) attributable to OP unitholders (in dollars per share)	$0.05	$0.06	$0.35	$0.16
Weighted average OP units outstanding - basic and diluted	183,279	184,281	183,279	184,281

Consolidated_Statements_of_Com

Consolidated Statements of Comprehensive Income / (Loss) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Net income/(loss)	$41,992	$3,235	$92,090	$8,280
Other comprehensive income/(loss), including portion attributable to noncontrolling interests:	'	'	'	'
Unrealized holding gain/(loss)	362	-386	611	-334
(Gain)/loss reclassifed into earnings from other comprehensive income/(loss)	1,130	1,635	3,809	5,180
Other comprehensive income/(loss), including portion attributable to noncontrolling interests	1,492	1,249	4,420	4,846
Comprehensive income/(loss)	43,484	4,484	96,510	13,126
Comprehensive (income)/loss attributable to noncontrolling interests	-1,500	-92	-3,336	-364
Comprehensive income/(loss) attributable to UDR, Inc.	$41,984	$4,392	$93,174	$12,762

Consolidated_Statements_of_Com1

Consolidated Statements of Comprehensive Income / (Loss) (UNITED DOMINION REALTY, L.P.) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Net income/(loss)	$41,992	$3,235	$92,090	$8,280
Other comprehensive income/(loss), including portion attributable to noncontrolling interests:	'	'	'	'
Unrealized holding gain/(loss)	362	-386	611	-334
(Gain)/loss reclassifed into earnings from other comprehensive income/(loss)	1,130	1,635	3,809	5,180
Other comprehensive income/(loss), including portion attributable to noncontrolling interests	1,492	1,249	4,420	4,846
Comprehensive income/(loss)	43,484	4,484	96,510	13,126
Comprehensive (income)/loss attributable to noncontrolling interests	1,500	92	3,336	364
Comprehensive income/(loss) attributable to OP unitholders	41,984	4,392	93,174	12,762
United Dominion Reality L.P. [Member]	'	'	'	'
Net income/(loss)	8,875	11,050	64,293	29,044
Other comprehensive income/(loss), including portion attributable to noncontrolling interests:	'	'	'	'
Unrealized holding gain/(loss)	-3	-201	-194	-284
(Gain)/loss reclassifed into earnings from other comprehensive income/(loss)	588	590	1,784	2,041
Other comprehensive income/(loss), including portion attributable to noncontrolling interests	585	389	1,590	1,757
Comprehensive income/(loss)	9,460	11,439	65,883	30,801
Comprehensive (income)/loss attributable to noncontrolling interests	238	39	697	151
Comprehensive income/(loss) attributable to OP unitholders	$9,222	$11,400	$65,186	$30,650

Consolidated_Statements_of_Cha

Consolidated Statements of Changes in Equity (Unaudited) (USD $)	Total	Preferred Stock [Member]	Common Stock [Member]	Paid - in Capital	Distributions in Excess of Net Income	Accumulated Other Comprehensive Income/(Loss)	Noncontrolling Interests [Member]
In Thousands, except Share data, unless otherwise specified
Beginning Balance at Dec. 31, 2013	$2,812,504	$46,571	$2,507	$4,109,765	($1,342,070)	($5,125)	$856
Beginning Balance, Shares at Dec. 31, 2013	'	2,803,812	250,749,665	'	'	'	'
Stock Issued During Period, Shares, Conversion of Units	'	'	151,453	'	'	'	'
Consolidted Statements of Changes in Equity	'	'	'	'	'	'	'
Net income/(loss) attributable to UDR, Inc.	88,917	'	'	'	88,917	'	'
Net income/(loss) attributable to noncontrolling interests	2	'	'	'	'	'	2
Other comprehensive income/(loss)	4,259	'	'	'	'	4,259	'
Issuance/(forfeiture) of common and restricted shares, net Shares	'	'	-904,354	'	'	'	'
Issuance/(forfeitures) of common and restricted shares, net	9,864	'	9	9,855	'	'	'
Issuance of common shares through public offering, shares	'	'	3,410,433	'	'	'	'
Issuance of common shares through public offering	99,991	'	34	99,957	'	'	'
Adjustment for conversion of noncontrolling interest of unitholders in Operating Partnership	4,318	'	2	4,316	'	'	'
Common stock distributions declared ($0.78 per share)	-197,173	'	'	'	-197,173	'	'
Preferred stock distributions declared-Series E ($0.9966 per share)	-2,793	'	'	'	-2,793	'	'
Adjustment to reflect redemption value of redeemable noncontrolling interests	-40,771	'	'	'	-40,771	'	'
Ending Balance at Sep. 30, 2014	$2,779,118	$46,571	$2,552	$4,223,893	($1,493,890)	($866)	$858
Ending Balance, Shares at Sep. 30, 2014	'	2,803,812	255,215,905	'	'	'	'

Consolidated_Statements_of_Cha1

Consolidated Statements of Changes in Equity (Unaudited) (Parenthetical) (USD $)	9 Months Ended
	Sep. 30, 2014
Common distributions declared per share	$0.78
Series E Preferred Stock [Member]	'
Preferred stock distributions declared	$1.00

Consolidated_Statements_of_Cha2

Consolidated Statements of Changes in Capital (UNITED DOMINION REALTY, L.P) (Unaudited) (USD $)	3 Months Ended	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2014
Other comprehensive income (loss)	$1,492	$4,420
United Dominion Reality L.P. [Member]	'	'
Balance, December 31, 2013	'	1,803,097
Net income/(loss)	'	64,293
Distributions	'	-143,362
Adjustment to reflect limited partners' capital at redemption value	0	'
Other comprehensive income (loss)	585	1,590
Net change in amount due to/(from) General Partner	'	10,711
Partners' Capital Account, Exchanges and Conversions	0	'
Balance, June 30, 2014	1,736,329	1,736,329
Payable/(Receivable) due to/(from) General Partner [Member] [Member] | United Dominion Reality L.P. [Member]	'	'
Balance, December 31, 2013	'	-9,916
Net change in amount due to/(from) General Partner	'	10,711
Balance, June 30, 2014	795	795
Accumulated Other Comprehensive Income (Loss) [Member] | United Dominion Reality L.P. [Member]	'	'
Balance, December 31, 2013	'	-3,065
Other comprehensive income (loss)	'	1,590
Balance, June 30, 2014	-1,475	-1,475
Total Partner's Capital [Member] | United Dominion Reality L.P. [Member]	'	'
Balance, December 31, 2013	'	1,795,934
Net income/(loss)	'	63,596
Distributions	'	-143,362
Adjustment to reflect limited partners' capital at redemption value	0	'
Other comprehensive income (loss)	'	1,590
Balance, June 30, 2014	1,717,758	1,717,758
Noncontrolling Interests [Member] | United Dominion Reality L.P. [Member]	'	'
Balance, December 31, 2013	'	17,079
Net income/(loss)	'	697
Balance, June 30, 2014	17,776	17,776
Partnership Capital [Member] | United Dominion Reality L.P. [Member]	'	'
Partners' Capital Account, Exchanges and Conversions	0	'
Class A Limited Partner [Member] | United Dominion Reality L.P. [Member]	'	'
Balance, December 31, 2013	'	40,902
Net income/(loss)	'	608
Distributions	'	-1,746
Adjustment to reflect limited partners' capital at redemption value	'	7,969
Balance, June 30, 2014	47,733	47,733
Limited Partners [Member] | United Dominion Reality L.P. [Member]	'	'
Balance, December 31, 2013	'	176,695
Net income/(loss)	'	2,618
Distributions	'	-5,861
Adjustment to reflect limited partners' capital at redemption value	'	32,946
Partners' Capital Account, Exchanges and Conversions	'	-4,317
Balance, June 30, 2014	202,081	202,081
Limited Partner [Member] | United Dominion Reality L.P. [Member]	'	'
Balance, December 31, 2013	'	1,580,239
Net income/(loss)	'	60,332
Distributions	'	-135,668
Adjustment to reflect limited partners' capital at redemption value	'	-40,915
Partners' Capital Account, Exchanges and Conversions	'	4,317
Balance, June 30, 2014	1,468,305	1,468,305
General Partner [Member] | United Dominion Reality L.P. [Member]	'	'
Balance, December 31, 2013	'	1,163
Net income/(loss)	'	38
Distributions	'	-87
Balance, June 30, 2014	$1,114	$1,114

Consolidated_Statements_of_Cas

Consolidated Statements of Cash Flows (Unaudited) (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013
Operating Activities	'	'
Net income/(loss)	$92,090	$8,280
Adjustments to reconcile net income/(loss) to net cash provided by operating activities:	'	'
Depreciation and amortization	270,405	256,299
Gain on sale of real estate owned, net of tax	-82,380	0
Tax benefit, net	-8,049	-7,314
Loss from unconsolidated entities	4,932	6,081
Casualty-related (recoveries)/charges, net	500	-618
Other	19,952	19,641
Changes in operating assets and liabilities:	'	'
(Increase)/decrease in operating assets	-5,870	-12,543
Increase/(decrease) in operating liabilities	-9,602	-8,529
Net cash provided by operating activities	281,978	261,297
Investing Activities	'	'
Acquisition of real estate assets	-199,012	0
Proceeds from sales of real estate investments, net	233,913	140,834
Development of real estate assets	-160,643	-229,650
Capital expenditures and other major improvements - real estate assets, net of escrow reimbursement	-82,332	-112,822
Capital expenditures - non-real estate assets	-4,277	-6,174
Investment in unconsolidated joint ventures	-167,160	-24,626
Distributions received from unconsolidated joint venture	17,884	106,618
Purchase deposits on pending acquisitions	-4,000	0
Repayment/(issuance) of notes receivable	64,715	-2,680
Net cash provided by/(used in) investing activities	-300,912	-128,500
Financing Activities	'	'
Payments on secured debt	-44,390	-44,525
Proceeds from the issuance of secured debt	5,502	0
Payments on unsecured debt	-312,500	-122,500
Proceeds from issuance of unsecured debt	298,956	299,943
Net proceeds of revolving bank debt	160,000	-76,000
Proceeds from the issuance of common shares through public offering, net	-99,991	0
Distributions paid to redeemable noncontrolling interests	-7,419	-6,987
Distributions paid to preferred stockholders	-2,793	-2,794
Distributions paid to common stockholders	-189,742	-172,897
Other	-4,315	-8,003
Net cash provided by/(used in) financing activities	3,290	-133,763
Net increase/(decrease) in cash and cash equivalents	-15,644	-966
Cash and cash equivalents, beginning of period	30,249	12,115
Cash and cash equivalents, end of period	14,605	11,149
Supplemental Information:	'	'
Interest paid during the period, net of amounts capitalized	105,232	99,266
Non-cash transactions:	'	'
Conversion of OP Units into common shares (151,453 shares in 2014 and 71,841 shares in 2013)	4,318	1,711
Transfer of real estate owned to investment in and advances to unconsolidated joint ventures	$0	$139,950

Consolidated_Statements_of_Cas1

Consolidated Statements of Cash Flows (Unaudited) (Parenthetical)	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Non-cash transactions:	'	'
Conversion of OP Units into common shares	151,453	71,841

Consolidated_Statements_of_Cas2

Consolidated Statements of Cash Flows (UNITED DOMINION REALTY, L.P) (Unaudited) (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013
Operating Activities	'	'
Net income/(loss)	$92,090	$8,280
Adjustments to reconcile net income/(loss) to net cash provided by operating activities:	'	'
Depreciation and amortization	270,405	256,299
Gain on sale of real estate owned	-82,305	0
Casualty-related (recoveries)/charges, net	500	-618
Other	19,952	19,641
Changes in operating assets and liabilities:	'	'
(Increase)/decrease in operating assets	-5,870	-12,543
Increase/(decrease) in operating liabilities	-9,602	-8,529
Net cash provided by operating activities	281,978	261,297
Investing Activities	'	'
Proceeds from sales of real estate investments, net	233,913	140,834
Development of real estate assets	-160,643	-229,650
Capital expenditures and other major improvements - real estate assets, net of escrow reimbursement	-82,332	-112,822
Net cash provided by/(used in) investing activities	-300,912	-128,500
Financing Activities	'	'
Proceeds from the issuance of secured debt	5,502	0
Payments on secured debt	-44,390	-44,525
Net cash provided by/(used in) financing activities	3,290	-133,763
Net increase/(decrease) in cash and cash equivalents	-15,644	-966
Cash and cash equivalents, beginning of period	30,249	12,115
Cash and cash equivalents, end of period	14,605	11,149
Supplemental Information:	'	'
Interest paid during the period, net of amounts capitalized	105,232	99,266
Non-cash transactions:	'	'
Reallocation of Credit Facilities Debt from General Partner	0	13,682
United Dominion Reality L.P. [Member]	'	'
Operating Activities	'	'
Net income/(loss)	64,293	29,044
Adjustments to reconcile net income/(loss) to net cash provided by operating activities:	'	'
Depreciation and amortization	134,011	135,555
Gain on sale of real estate owned	-40,687	0
Casualty-related (recoveries)/charges, net	500	-618
Other	187	2,413
Changes in operating assets and liabilities:	'	'
(Increase)/decrease in operating assets	-2,540	-10,201
Increase/(decrease) in operating liabilities	2,077	8,495
Net cash provided by operating activities	157,841	164,688
Investing Activities	'	'
Proceeds from sales of real estate investments, net	47,922	0
Development of real estate assets	-41,701	-45,490
Capital expenditures and other major improvements - real estate assets, net of escrow reimbursement	-32,631	-59,223
Net cash provided by/(used in) investing activities	-26,410	-104,713
Financing Activities	'	'
Advances from/(to) General Partner, net	-120,698	-11,199
Payments on secured debt	-3,727	-41,034
Distributions paid to partnership unitholders	-7,419	-6,987
Payment of financing costs	0	-1,137
Net cash provided by/(used in) financing activities	-131,844	-60,357
Net increase/(decrease) in cash and cash equivalents	-413	-382
Cash and cash equivalents, beginning of period	1,897	2,804
Cash and cash equivalents, end of period	1,484	2,422
Supplemental Information:	'	'
Interest paid during the period, net of amounts capitalized	$32,792	$31,933

Consolidation_and_Basis_of_Pre

Consolidation and Basis of Presentation	9 Months Ended
	Sep. 30, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]	'
CONSOLIDATION AND BASIS OF PRESENTATION	'
	CONSOLIDATION AND BASIS OF PRESENTATION
	Consolidation and Basis of Presentation
	UDR, Inc., collectively with our consolidated subsidiaries (“UDR,” the “Company,” “we,” “our,” or “us”) is a self-administered real estate investment trust, or REIT, that owns, operates, acquires, renovates, develops, redevelops, and manages apartment communities. The accompanying consolidated financial statements include the accounts of UDR and its subsidiaries, including United Dominion Realty, L.P. (the “Operating Partnership” or the “OP”). As of September 30, 2014, there were 183,278,698 units in the Operating Partnership outstanding, of which 174,111,227 units, or 95.0%, were owned by UDR and 9,167,471 units, or 5.0%, were owned by limited partners. The consolidated financial statements of UDR include the noncontrolling interests of the unitholders in the Operating Partnership.
	The accompanying interim unaudited consolidated financial statements have been prepared according to the rules and regulations of the Securities and Exchange Commission. Certain information and note disclosures normally included in financial statements prepared in accordance with accounting principles generally accepted in the United States have been condensed or omitted according to such rules and regulations, although management believes that the disclosures are adequate to make the information presented not misleading. In the opinion of management, all adjustments and eliminations necessary for the fair presentation of our financial position as of September 30, 2014, and results of operations for the three and nine months ended September 30, 2014 and 2013 have been included. Such adjustments are normal and recurring in nature. The interim results presented are not necessarily indicative of results that can be expected for a full year. The accompanying interim unaudited consolidated financial statements should be read in conjunction with the audited consolidated financial statements and related notes for the year ended December 31, 2013 appearing in UDR’s Annual Report on Form 10-K, filed with the Securities and Exchange Commission on February 25, 2014.
	The accompanying interim unaudited consolidated financial statements are presented in accordance with U.S. generally accepted accounting principles (“GAAP”). GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent liabilities at the dates of the interim unaudited consolidated financial statements and the amounts of revenues and expenses during the reporting periods. Actual amounts realized or paid could differ from those estimates. All significant intercompany accounts and transactions have been eliminated in consolidation.
	The Company evaluated subsequent events through the date its financial statements were issued. No significant recognized or non-recognized subsequent events were noted.

Consolidation_and_Basis_of_Pre1

Consolidation and Basis of Presentation (UNITED DOMINION REALTY, L.P.)	9 Months Ended
	Sep. 30, 2014
Entity Information [Line Items]	'
CONSOLIDATION AND BASIS OF PRESENTATION	'
	CONSOLIDATION AND BASIS OF PRESENTATION
	Consolidation and Basis of Presentation
	UDR, Inc., collectively with our consolidated subsidiaries (“UDR,” the “Company,” “we,” “our,” or “us”) is a self-administered real estate investment trust, or REIT, that owns, operates, acquires, renovates, develops, redevelops, and manages apartment communities. The accompanying consolidated financial statements include the accounts of UDR and its subsidiaries, including United Dominion Realty, L.P. (the “Operating Partnership” or the “OP”). As of September 30, 2014, there were 183,278,698 units in the Operating Partnership outstanding, of which 174,111,227 units, or 95.0%, were owned by UDR and 9,167,471 units, or 5.0%, were owned by limited partners. The consolidated financial statements of UDR include the noncontrolling interests of the unitholders in the Operating Partnership.
	The accompanying interim unaudited consolidated financial statements have been prepared according to the rules and regulations of the Securities and Exchange Commission. Certain information and note disclosures normally included in financial statements prepared in accordance with accounting principles generally accepted in the United States have been condensed or omitted according to such rules and regulations, although management believes that the disclosures are adequate to make the information presented not misleading. In the opinion of management, all adjustments and eliminations necessary for the fair presentation of our financial position as of September 30, 2014, and results of operations for the three and nine months ended September 30, 2014 and 2013 have been included. Such adjustments are normal and recurring in nature. The interim results presented are not necessarily indicative of results that can be expected for a full year. The accompanying interim unaudited consolidated financial statements should be read in conjunction with the audited consolidated financial statements and related notes for the year ended December 31, 2013 appearing in UDR’s Annual Report on Form 10-K, filed with the Securities and Exchange Commission on February 25, 2014.
	The accompanying interim unaudited consolidated financial statements are presented in accordance with U.S. generally accepted accounting principles (“GAAP”). GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent liabilities at the dates of the interim unaudited consolidated financial statements and the amounts of revenues and expenses during the reporting periods. Actual amounts realized or paid could differ from those estimates. All significant intercompany accounts and transactions have been eliminated in consolidation.
	The Company evaluated subsequent events through the date its financial statements were issued. No significant recognized or non-recognized subsequent events were noted.
United Dominion Reality L.P. [Member]	'
Entity Information [Line Items]	'
CONSOLIDATION AND BASIS OF PRESENTATION	'
	CONSOLIDATION AND BASIS OF PRESENTATION
	Consolidation and Basis of Presentation
	United Dominion Realty, L.P. (“UDR, L.P.,” the “Operating Partnership,” “we” or “our”) is a Delaware limited partnership, that owns, acquires, renovates, redevelops, manages, and disposes of multifamily apartment communities generally located in high barrier to entry markets located in the United States. The high barrier to entry markets are characterized by limited land for new construction, difficult and lengthy entitlement process, expensive single-family home prices and significant employment growth potential. UDR, L.P. is a subsidiary of UDR, Inc. (“UDR” or the “General Partner”), a self-administered real estate investment trust, or REIT, through which UDR conducts a significant portion of its business. During the three and nine months ended September 30, 2014 and 2013, rental revenues of the Operating Partnership represented 53%, 53%, 55% and 54%, respectively, of the General Partner’s consolidated rental revenues (including those classified within discontinued operations). As of September 30, 2014, the Operating Partnership’s apartment portfolio consisted of 67 communities located in 17 markets consisting of 20,753 apartment homes.
	Interests in UDR, L.P. are represented by operating partnership units (“OP Units”). The Operating Partnership’s net income is allocated to the partners, which is initially based on their respective distributions made during the year and secondly, their percentage interests. Distributions are made in accordance with the terms of the Amended and Restated Agreement of Limited Partnership of United Dominion Realty, L.P. (the “Operating Partnership Agreement”), on a per unit basis that is generally equal to the dividend per share on UDR’s common stock, which is publicly traded on the New York Stock Exchange (“NYSE”) under the ticker symbol “UDR”.
	As of September 30, 2014, there were 183,278,698 OP Units outstanding, of which 174,111,227 or 95.0% were owned by UDR and affiliated entities and 9,167,471 or 5.0% were owned by non-affiliated limited partners. See Note 9, Capital Structure.
	The accompanying interim unaudited consolidated financial statements have been prepared according to the rules and regulations of the Securities and Exchange Commission (“SEC”). Certain information and note disclosures normally included in financial statements prepared in accordance with accounting principles generally accepted in the United States have been condensed or omitted according to such rules and regulations, although management believes that the disclosures are adequate to make the information presented not misleading. In the opinion of management, all adjustments and eliminations necessary for the fair presentation of our financial position as of September 30, 2014, and results of operations for the three and nine months ended September 30, 2014 and 2013 have been included. Such adjustments are normal and recurring in nature. The interim results presented are not necessarily indicative of results that can be expected for a full year. The accompanying interim unaudited consolidated financial statements should be read in conjunction with the audited consolidated financial statements and related notes for the year ended December 31, 2013 included in the Annual Report on Form 10-K filed by UDR and the Operating Partnership with the SEC on February 25, 2014.
	The accompanying interim unaudited consolidated statements are presented in accordance with U.S. generally accepted accounting principles (“GAAP”). GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent liabilities at the dates of the interim unaudited consolidated financial statements and the amounts of revenues and expenses during the reporting periods. Actual amounts realized or paid could differ from those estimates. All intercompany accounts and transactions have been eliminated in consolidation.
	The Operating Partnership evaluated subsequent events through the date its financial statements were issued. No recognized or non-recognized subsequent events were noted.

Significant_Accounting_Policie

Significant Accounting Policies	9 Months Ended
	Sep. 30, 2014
Accounting Policies [Abstract]	'
SIGNIFICANT ACCOUNTING POLICIES	'
	SIGNIFICANT ACCOUNTING POLICIES
	Recent Accounting Pronouncements
	In April 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2014-08, Reporting Discontinued Operations and Disclosures of Disposals of Components of an Entity, which incorporates a requirement that a disposition represent a strategic shift in an entity’s operations into the definition of a discontinued operation. In accordance with the ASU, a discontinued operation represents (1) a component of an entity or group of components that has been disposed of or is classified as held for sale in a single transaction and represents a strategic shift that has or will have a major effect on an entity’s financial results, or (2) an acquired business that is classified as held for sale on the date of acquisition. A strategic shift could include a disposal of (1) a separate major line of business, (2) a separate major geographic area of operations, (3) a major equity method investment, or (4) other major parts of an entity. The standard requires prospective application and will be effective for interim and annual periods beginning on or after December 15, 2014, with early adoption permitted. The early adoption provision excludes components of an entity that were sold or classified as held for sale prior to the adoption of the standard.
	The Company elected to early adopt this standard effective January 1, 2014, which had a significant impact on the Company’s consolidated financial statements as further discussed in Note 4, Discontinued Operations. Subsequent to the Company’s adoption of ASU 2014-08, the sale of real estate that does not meet the definition of a discontinued operation under the standard is included in Gain/(loss) on sale of real estate owned, net of tax on the Consolidated Statements of Operations.
	In May 2014, FASB issued ASU No. 2014-09, Revenue from Contracts with Customers. The standard provides companies with a single model for use in accounting for revenue arising from contracts with customers and supersedes current revenue recognition guidance, including industry-specific revenue guidance. The updated standard will replace most existing revenue recognition guidance in U.S. GAAP when it becomes effective. The standard specifically excludes lease contracts. The ASU allows for the use of either the full or modified retrospective transition method, and the standard will be effective for the Company on January 1, 2017; early adoption is not permitted. The Company has not yet selected a transition method and we are currently evaluating the effect that the updated standard will have on our consolidated financial statements and related disclosures.
	Revenue and Real Estate Sales Gain Recognition
	Rental income related to leases is recognized on an accrual basis when due from residents and tenants in accordance with GAAP. Rental payments are generally due on a monthly basis and recognized when earned. The Company recognizes interest income, management and other fees and incentives when earned, and the amounts are fixed and determinable.
	For sale transactions meeting the requirements for full accrual profit recognition, we remove the related assets and liabilities from our Consolidated Balance Sheets and record the gain or loss in the period the transaction closes. For sale transactions that do not meet the full accrual sale criteria due to our continuing involvement, we evaluate the nature of the continuing involvement and account for the transaction under an alternate method of accounting. Unless certain limited criteria are met, non-monetary transactions, including property exchanges, are accounted for at fair value.
	Sales to entities in which we retain or otherwise own an interest are accounted for as partial sales. If all other requirements for recognizing profit under the full accrual method have been satisfied and no other forms of continuing involvement are present, we recognize profit proportionate to the outside interest in the buyer and defer the gain on the interest we retain. The Company recognizes any deferred gain when the property is sold to a third party. In transactions accounted for by us as partial sales, we determine if the buyer of the majority equity interest in the venture was provided a preference as to cash flows in either an operating or a capital waterfall. If a cash flow preference has been provided, we recognize profit only to the extent that proceeds from the sale of the majority equity interest exceed costs related to the entire property.
	Notes Receivable
	The following table summarizes our notes receivable, net as of September 30, 2014 and December 31, 2013 (dollars in thousands):
		Balance outstanding
		September 30, 2014		December 31, 2013		Interest rate at September 30, 2014
	Note due June 2014 (a)	$	—	$	40,800	—	%
	Note due February 2017 (b)	15,818		14,580		10	%
	Note due July 2017 (c)	2,500		1,400		8	%
	Note due June 2022 (net of discount of $0 and $247, respectively) (d)	—		26,253		—	%
	Total notes receivable, net	$	18,318	$	83,033
	(a) In the fourth quarter of 2013, in conjunction with the sale of its 95% interest in the Lodge at Stoughton, one of its unconsolidated joint ventures, the Company provided the buyer with a $40.8 million loan secured by the property at LIBOR plus a spread of 350 basis points with two three-month extension options at increased rates and a financing fee. In June 2014, the note was paid in full.
	(b) The Company has a secured note receivable with an unaffiliated third party with an aggregate commitment of $15.8 million, which bears an interest rate of 10.00% per annum. During the nine months ended September 30, 2014, the Company loaned an additional $1.2 million under the note. Interest payments are due monthly. The note matures at the earliest of the following: (a) the closing of any private or public capital raising in the amount of $5.0 million or greater; (b) an acquisition; (c) acceleration in the event of default; or (d) the fifth anniversary of the date of the note (February 2017).
	(c) The Company has a secured note receivable with an unaffiliated third party with an aggregate commitment of $2.5 million, which bears an interest rate of 8.00% per annum. During the nine months ended September 30, 2014, the Company loaned an additional $1.1 million. Interest payments are due monthly. The note matures at the earliest of the following: (a) the closing of any private or public capital raising in the amount of $5.0 million or greater; (b) an acquisition; (c) acceleration in the event of default; or (d) the fifth anniversary of the date of the note (July 2017).
	(d) In 2012, the Company purchased a "B" Note secured by a first mortgage on a class A community in West Los Angeles. The $26.5 million loan was purchased at a yield of 7.25% and bore a coupon rate of 7.00%. Interest payments are due monthly and the note is due June 2022. The discount is amortized using the effective interest method. In July 2014, the Company received proceeds of $36.0 million from the repayment of this note, resulting in a net gain of approximately $8.4 million, which is included in Interest and other income/(expense), net on the Consolidated Statements of Operations.
	The Company recognized $0.4 million and $3.0 million of interest income from these notes receivable during the three and nine months ended September 30, 2014, respectively, and $1.1 million and $3.1 million during the three and nine months ended September 30, 2013, respectively. Included in the three and nine months ended September 30, 2013 are $184,000 and $547,000 of related party interest income, respectively. Interest income is included in Interest and other income/(expense), net on the Consolidated Statements of Operations.
	Comprehensive Income/(Loss)
	Comprehensive income/(loss), which is defined as the change in equity during each period from transactions and other events and circumstances from nonowner sources, including all changes in equity during a period except for those resulting from investments by or distributions to stockholders, is displayed in the accompanying Consolidated Statements of Comprehensive Income/(Loss). For the three and nine months ended September 30, 2014 and 2013, the Company’s other comprehensive income/(loss) consisted of the gain/(loss) (effective portion) on derivative instruments that are designated as and qualify as cash flow hedges, (gain)/loss on derivative instruments reclassified from other comprehensive income/(loss) into earnings, and the allocation of other comprehensive income/(loss) to redeemable noncontrolling interests. The (gain)/loss on derivative instruments reclassified from other comprehensive income/(loss) is included in Interest expense on the Consolidated Statements of Operations. See Note 10, Derivatives and Hedging Activity, for further discussion. The allocation of other comprehensive income/(loss) to redeemable noncontrolling interests was $57,000 and $163,000 during the three and nine months ended September 30, 2014, respectively, and $45,000 and $196,000 during the three and nine months ended September 30, 2013, respectively.
	Income Taxes
	Due to the structure of the Company as a REIT and the nature of the operations for the operating properties, no provision for federal income taxes has been provided for at UDR. Historically, the Company has generally incurred only state and local excise and franchise taxes. UDR has elected for certain consolidated subsidiaries to be treated as taxable REIT subsidiaries (“TRS”), primarily those engaged in development activities.
	Income taxes for our TRS, RE3, are accounted for under the asset and liability method. Deferred tax assets and liabilities are recognized for future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax basis. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities from a change in tax rate is recognized in earnings in the period of the enactment date. The Company’s deferred tax assets are generally the result of differing depreciable lives on capitalized assets and timing of expense recognition for certain accrued liabilities. As of September 30, 2014, UDR’s net deferred tax asset was $9.1 million (net of a valuation allowance of $1.4 million), which is included in Other assets on the Consolidated Balance Sheets.
	GAAP defines a recognition threshold and measurement attribute for the financial statement recognition and measurement of a tax position taken or expected to be taken in a tax return. GAAP also provides guidance on derecognition, classification, interest and penalties, accounting for interim periods, disclosure and transition.
	The Company recognizes its tax positions and evaluates them using a two-step process. First, UDR determines whether a tax position is more likely than not (greater than 50 percent probability) to be sustained upon examination, including resolution of any related appeals or litigation processes, based on the technical merits of the position. Second, the Company will determine the amount of benefit to recognize and record the amount that is more likely than not to be realized upon ultimate settlement.
	UDR had no material unrecognized tax benefit, accrued interest or penalties at September 30, 2014. UDR and its subsidiaries are subject to federal income tax as well as income tax of various state and local jurisdictions. The tax years 2010 through 2013 remain open to examination by tax jurisdictions to which we are subject. When applicable, UDR recognizes interest and/or penalties related to uncertain tax positions in Tax benefit/(expense), net on the Consolidated Statements of Operations.

Significant_Accounting_Policie1

Significant Accounting Policies (UNITED DOMINION REALTY, L.P.)	9 Months Ended
	Sep. 30, 2014
Entity Information [Line Items]	'
SIGNIFICANT ACCOUNTING POLICIES	'
	SIGNIFICANT ACCOUNTING POLICIES
	Recent Accounting Pronouncements
	In April 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2014-08, Reporting Discontinued Operations and Disclosures of Disposals of Components of an Entity, which incorporates a requirement that a disposition represent a strategic shift in an entity’s operations into the definition of a discontinued operation. In accordance with the ASU, a discontinued operation represents (1) a component of an entity or group of components that has been disposed of or is classified as held for sale in a single transaction and represents a strategic shift that has or will have a major effect on an entity’s financial results, or (2) an acquired business that is classified as held for sale on the date of acquisition. A strategic shift could include a disposal of (1) a separate major line of business, (2) a separate major geographic area of operations, (3) a major equity method investment, or (4) other major parts of an entity. The standard requires prospective application and will be effective for interim and annual periods beginning on or after December 15, 2014, with early adoption permitted. The early adoption provision excludes components of an entity that were sold or classified as held for sale prior to the adoption of the standard.
	The Company elected to early adopt this standard effective January 1, 2014, which had a significant impact on the Company’s consolidated financial statements as further discussed in Note 4, Discontinued Operations. Subsequent to the Company’s adoption of ASU 2014-08, the sale of real estate that does not meet the definition of a discontinued operation under the standard is included in Gain/(loss) on sale of real estate owned, net of tax on the Consolidated Statements of Operations.
	In May 2014, FASB issued ASU No. 2014-09, Revenue from Contracts with Customers. The standard provides companies with a single model for use in accounting for revenue arising from contracts with customers and supersedes current revenue recognition guidance, including industry-specific revenue guidance. The updated standard will replace most existing revenue recognition guidance in U.S. GAAP when it becomes effective. The standard specifically excludes lease contracts. The ASU allows for the use of either the full or modified retrospective transition method, and the standard will be effective for the Company on January 1, 2017; early adoption is not permitted. The Company has not yet selected a transition method and we are currently evaluating the effect that the updated standard will have on our consolidated financial statements and related disclosures.
	Revenue and Real Estate Sales Gain Recognition
	Rental income related to leases is recognized on an accrual basis when due from residents and tenants in accordance with GAAP. Rental payments are generally due on a monthly basis and recognized when earned. The Company recognizes interest income, management and other fees and incentives when earned, and the amounts are fixed and determinable.
	For sale transactions meeting the requirements for full accrual profit recognition, we remove the related assets and liabilities from our Consolidated Balance Sheets and record the gain or loss in the period the transaction closes. For sale transactions that do not meet the full accrual sale criteria due to our continuing involvement, we evaluate the nature of the continuing involvement and account for the transaction under an alternate method of accounting. Unless certain limited criteria are met, non-monetary transactions, including property exchanges, are accounted for at fair value.
	Sales to entities in which we retain or otherwise own an interest are accounted for as partial sales. If all other requirements for recognizing profit under the full accrual method have been satisfied and no other forms of continuing involvement are present, we recognize profit proportionate to the outside interest in the buyer and defer the gain on the interest we retain. The Company recognizes any deferred gain when the property is sold to a third party. In transactions accounted for by us as partial sales, we determine if the buyer of the majority equity interest in the venture was provided a preference as to cash flows in either an operating or a capital waterfall. If a cash flow preference has been provided, we recognize profit only to the extent that proceeds from the sale of the majority equity interest exceed costs related to the entire property.
	Notes Receivable
	The following table summarizes our notes receivable, net as of September 30, 2014 and December 31, 2013 (dollars in thousands):
		Balance outstanding
		September 30, 2014		December 31, 2013		Interest rate at September 30, 2014
	Note due June 2014 (a)	$	—	$	40,800	—	%
	Note due February 2017 (b)	15,818		14,580		10	%
	Note due July 2017 (c)	2,500		1,400		8	%
	Note due June 2022 (net of discount of $0 and $247, respectively) (d)	—		26,253		—	%
	Total notes receivable, net	$	18,318	$	83,033
	(a) In the fourth quarter of 2013, in conjunction with the sale of its 95% interest in the Lodge at Stoughton, one of its unconsolidated joint ventures, the Company provided the buyer with a $40.8 million loan secured by the property at LIBOR plus a spread of 350 basis points with two three-month extension options at increased rates and a financing fee. In June 2014, the note was paid in full.
	(b) The Company has a secured note receivable with an unaffiliated third party with an aggregate commitment of $15.8 million, which bears an interest rate of 10.00% per annum. During the nine months ended September 30, 2014, the Company loaned an additional $1.2 million under the note. Interest payments are due monthly. The note matures at the earliest of the following: (a) the closing of any private or public capital raising in the amount of $5.0 million or greater; (b) an acquisition; (c) acceleration in the event of default; or (d) the fifth anniversary of the date of the note (February 2017).
	(c) The Company has a secured note receivable with an unaffiliated third party with an aggregate commitment of $2.5 million, which bears an interest rate of 8.00% per annum. During the nine months ended September 30, 2014, the Company loaned an additional $1.1 million. Interest payments are due monthly. The note matures at the earliest of the following: (a) the closing of any private or public capital raising in the amount of $5.0 million or greater; (b) an acquisition; (c) acceleration in the event of default; or (d) the fifth anniversary of the date of the note (July 2017).
	(d) In 2012, the Company purchased a "B" Note secured by a first mortgage on a class A community in West Los Angeles. The $26.5 million loan was purchased at a yield of 7.25% and bore a coupon rate of 7.00%. Interest payments are due monthly and the note is due June 2022. The discount is amortized using the effective interest method. In July 2014, the Company received proceeds of $36.0 million from the repayment of this note, resulting in a net gain of approximately $8.4 million, which is included in Interest and other income/(expense), net on the Consolidated Statements of Operations.
	The Company recognized $0.4 million and $3.0 million of interest income from these notes receivable during the three and nine months ended September 30, 2014, respectively, and $1.1 million and $3.1 million during the three and nine months ended September 30, 2013, respectively. Included in the three and nine months ended September 30, 2013 are $184,000 and $547,000 of related party interest income, respectively. Interest income is included in Interest and other income/(expense), net on the Consolidated Statements of Operations.
	Comprehensive Income/(Loss)
	Comprehensive income/(loss), which is defined as the change in equity during each period from transactions and other events and circumstances from nonowner sources, including all changes in equity during a period except for those resulting from investments by or distributions to stockholders, is displayed in the accompanying Consolidated Statements of Comprehensive Income/(Loss). For the three and nine months ended September 30, 2014 and 2013, the Company’s other comprehensive income/(loss) consisted of the gain/(loss) (effective portion) on derivative instruments that are designated as and qualify as cash flow hedges, (gain)/loss on derivative instruments reclassified from other comprehensive income/(loss) into earnings, and the allocation of other comprehensive income/(loss) to redeemable noncontrolling interests. The (gain)/loss on derivative instruments reclassified from other comprehensive income/(loss) is included in Interest expense on the Consolidated Statements of Operations. See Note 10, Derivatives and Hedging Activity, for further discussion. The allocation of other comprehensive income/(loss) to redeemable noncontrolling interests was $57,000 and $163,000 during the three and nine months ended September 30, 2014, respectively, and $45,000 and $196,000 during the three and nine months ended September 30, 2013, respectively.
	Income Taxes
	Due to the structure of the Company as a REIT and the nature of the operations for the operating properties, no provision for federal income taxes has been provided for at UDR. Historically, the Company has generally incurred only state and local excise and franchise taxes. UDR has elected for certain consolidated subsidiaries to be treated as taxable REIT subsidiaries (“TRS”), primarily those engaged in development activities.
	Income taxes for our TRS, RE3, are accounted for under the asset and liability method. Deferred tax assets and liabilities are recognized for future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax basis. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities from a change in tax rate is recognized in earnings in the period of the enactment date. The Company’s deferred tax assets are generally the result of differing depreciable lives on capitalized assets and timing of expense recognition for certain accrued liabilities. As of September 30, 2014, UDR’s net deferred tax asset was $9.1 million (net of a valuation allowance of $1.4 million), which is included in Other assets on the Consolidated Balance Sheets.
	GAAP defines a recognition threshold and measurement attribute for the financial statement recognition and measurement of a tax position taken or expected to be taken in a tax return. GAAP also provides guidance on derecognition, classification, interest and penalties, accounting for interim periods, disclosure and transition.
	The Company recognizes its tax positions and evaluates them using a two-step process. First, UDR determines whether a tax position is more likely than not (greater than 50 percent probability) to be sustained upon examination, including resolution of any related appeals or litigation processes, based on the technical merits of the position. Second, the Company will determine the amount of benefit to recognize and record the amount that is more likely than not to be realized upon ultimate settlement.
	UDR had no material unrecognized tax benefit, accrued interest or penalties at September 30, 2014. UDR and its subsidiaries are subject to federal income tax as well as income tax of various state and local jurisdictions. The tax years 2010 through 2013 remain open to examination by tax jurisdictions to which we are subject. When applicable, UDR recognizes interest and/or penalties related to uncertain tax positions in Tax benefit/(expense), net on the Consolidated Statements of Operations.
United Dominion Reality L.P. [Member]	'
Entity Information [Line Items]	'
SIGNIFICANT ACCOUNTING POLICIES	'
	SIGNIFICANT ACCOUNTING POLICIES
	Recent Accounting Pronouncements
	In April 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2014-08, Reporting Discontinued Operations and Disclosures of Disposals of Components of an Entity, which incorporates a requirement that a disposition represent a strategic shift in an entity’s operations into the definition of a discontinued operation. In accordance with the ASU, a discontinued operation represents (1) a component of an entity or group of components that has been disposed of or is classified as held for sale in a single transaction and represents a strategic shift that has or will have a major effect on an entity’s financial results, or (2) an acquired business that is classified as held for sale on the date of acquisition. A strategic shift could include a disposal of (1) a separate major line of business, (2) a separate major geographic area of operations, (3) a major equity method investment, or (4) other major parts of an entity. The standard requires prospective application and will be effective for interim and annual periods beginning on or after December 15, 2014, with early adoption permitted. The early adoption provision excludes components of an entity that were sold or classified as held for sale prior to the adoption of the standard.
	The Operating Partnership elected to early adopt this standard effective January 1, 2014, which had a significant impact on the Operating Partnership’s consolidated financial statements as further discussed in Note 4, Discontinued Operations. Subsequent to the Operating Partnership’s adoption of ASU 2014-08, the sale of real estate that does not meet the definition of a discontinued operation under the standard is included in Gain/(loss) on sale of real estate owned on the Consolidated Statements of Operations.
	In May 2014, FASB issued ASU No. 2014-09, Revenue from Contracts with Customers. The standard provides companies with a single model for use in accounting for revenue arising from contracts with customers and supersedes current revenue recognition guidance, including industry-specific revenue guidance. The updated standard will replace most existing revenue recognition guidance in U.S. GAAP when it becomes effective. The standard specifically excludes lease contracts. The ASU allows for the use of either the full or modified retrospective transition method, and the standard will be effective for the Operating Partnership on January 1, 2017; early adoption is not permitted. The Operating Partnership has not yet selected a transition method and we are currently evaluating the effect that the updated standard will have on its consolidated financial statements and related disclosures.
	Revenue and Real Estate Sales Gain Recognition
	Rental income related to leases is recognized on an accrual basis when due from residents and tenants in accordance with GAAP. Rental payments are generally due on a monthly basis and recognized when earned. The Operating Partnership recognizes interest income, fees and incentives when earned, fixed and determinable.
	For sale transactions meeting the requirements for full accrual profit recognition, we remove the related assets and liabilities from our Consolidated Balance Sheets and record the gain or loss in the period the transaction closes. For sale transactions that do not meet the full accrual sale criteria due to our continuing involvement, we evaluate the nature of the continuing involvement and account for the transaction under an alternate method of accounting. Unless certain limited criteria are met, non-monetary transactions, including property exchanges, are accounted for at fair value.
	Sales to entities in which we or our General Partner retain or otherwise own an interest are accounted for as partial sales. If all other requirements for recognizing profit under the full accrual method have been satisfied and no other forms of continuing involvement are present, we recognize profit proportionate to the outside interest in the buyer and defer the gain on the interest we or our General Partner retain. The Operating Partnership recognizes any deferred gain when the property is sold to a third party. In transactions accounted by us as partial sales, we determine if the buyer of the majority equity interest in the venture was provided a preference as to cash flows in either an operating or a capital waterfall. If a cash flow preference has been provided, we recognize profit only to the extent that proceeds from the sale of the majority equity interest exceed costs related to the entire property.
	Comprehensive Income/(Loss)
	Comprehensive income/(loss), which is defined as the change in equity during each period from transactions and other events and circumstances from nonowner sources, including all changes in equity during a period except for those resulting from investments by or distributions to unitholders, is displayed in the accompanying Consolidated Statements of Comprehensive Income/(Loss). For the three and nine months ended September 30, 2014 and 2013, the Operating Partnership’s other comprehensive income/(loss) consisted of the gain/(loss) (effective portion) on derivative instruments that are designated as and qualify as cash flow hedges and (gain)/loss reclassified from other comprehensive income/(loss) into earnings. The (gain)/loss reclassified from other comprehensive income/(loss) is included in Interest expense on the Consolidated Statements of Operations. See Note 8, Derivatives and Hedging Activity, for further discussion.
	Income Taxes
	The taxable income or loss of the Operating Partnership is reported on the tax returns of the partners. Accordingly, no provision has been made in the accompanying financial statements for federal or state income taxes on income that is passed through to the partners. However, any state or local revenue, excise or franchise taxes that result from the operating activities of the Operating Partnership are recorded at the entity level. The Operating Partnership’s tax returns are subject to examination by federal and state taxing authorities. Net income for financial reporting purposes differs from the net income for income tax reporting purposes primarily due to temporary differences, principally real estate depreciation and the tax deferral of certain gains on property sales. The differences in depreciation result from differences in the book and tax basis of certain real estate assets and the differences in the methods of depreciation and lives of the real estate assets.
	The Operating Partnership evaluates the accounting and disclosure of tax positions taken or expected to be taken in the course of preparing the Operating Partnership’s tax returns to determine whether the tax positions are “more-likely-than-not” of being sustained by the applicable tax authority. Tax positions not deemed to meet the more-likely-than-not threshold would be recorded as a tax benefit or expense in the current year. Management of the Operating Partnership is required to analyze all open tax years, as defined by the statute of limitations, for all major jurisdictions, which include federal and certain states. The Operating Partnership has no examinations in progress and none are expected at this time.
	Management of the Operating Partnership has reviewed all open tax years (2010 through 2013) of tax jurisdictions and concluded there is no tax liability resulting from unrecognized tax benefits relating to uncertain income tax positions taken or expected to be taken in future tax returns.

Real_Estate_Owned

Real Estate Owned	9 Months Ended
	Sep. 30, 2014
Real Estate [Abstract]	'
REAL ESTATE OWNED	'
	REAL ESTATE OWNED
	Real estate assets owned by the Company consist of income producing operating properties, properties under development, land held for future development, and sold or held for disposition properties. As of September 30, 2014, the Company owned and consolidated 141 communities in 10 states plus the District of Columbia totaling 40,477 apartment homes. The following table summarizes the carrying amounts for our real estate owned (at cost) as of September 30, 2014 and December 31, 2013 (dollars in thousands):
		September 30,			December 31, 2013
		2014
	Land and land improvements	$	1,955,007		$	1,847,127
	Depreciable property — held and used:
	Building, improvements, and furniture, fixtures and equipment	6,151,677			5,876,717
	Under development:
	Land and land improvements	47,038			110,769
	Building, improvements, and furniture, fixtures and equipment	274,569			356,644
	Real estate held for disposition:
	Land and land improvements	—			10,751
	Building, improvements, and furniture, fixtures and equipment	—			5,969
	Real estate owned	8,428,291			8,207,977
	Accumulated depreciation	(2,379,033		)	(2,208,794		)
	Real estate owned, net	$	6,049,258		$	5,999,183
	During the nine months ended September 30, 2014, the Company sold six communities with a total of 1,904 apartment homes, an adjacent parcel of land, and one operating property for gross proceeds of $237.7 million, resulting in net proceeds of $233.9 million and a total gain (net of tax) of $82.4 million. A portion of the sale proceeds was designated for tax-deferred exchanges under Section 1031 of the Internal Revenue Code and was used to fund acquisitions of real estate as discussed below. Gains (net of tax) of $82.3 million are included in Gain/(loss) on sale of real estate owned, net of tax on the Consolidated Statements of Operations. The remaining gains (net of tax) of $0.1 million related to the sale of one operating property, which was classified as held for disposition prior to the Company’s adoption of ASU 2014-08 (as described in Note 2, Significant Accounting Policies and Note 4, Discontinued Operations), and, therefore, was included in Income/(loss) from discontinued operations, net of tax on the Consolidated Statements of Operations.
	In January 2014, the Company acquired a fully-entitled land parcel for future development located in Huntington Beach, California for $77.8 million. In the third quarter of 2014, the Company acquired two communities, located in Seattle, Washington and Kirkland, Washington, with a total of 358 apartment homes for $45.5 million and $75.2 million, respectively. The three acquisitions during the nine months ended September 30, 2014 were accomplished through tax-deferred exchanges under Section 1031 of the Internal Revenue Code.
	There were no sales during the nine months ended September 30, 2013.
	Predevelopment, development, and redevelopment projects and related costs are capitalized and reported on the Consolidated Balance Sheets as Total real estate owned, net of accumulated depreciation. The Company capitalizes costs directly related to the predevelopment, development, and redevelopment of a capital project, which include, but are not limited to, interest, real estate taxes, insurance, and allocated development and redevelopment overhead related to support costs for personnel working on the capital projects. We use our professional judgment in determining whether such costs meet the criteria for capitalization or must be expensed as incurred. These costs are capitalized only during the period in which activities necessary to ready an asset for its intended use are in progress and such costs are incremental and identifiable to a specific activity to get the asset ready for its intended use. These costs, excluding the direct costs of development and redevelopment and capitalized interest, were $1.7 million and $7.2 million for the three and nine months ended September 30, 2014, respectively, and $2.4 million and $8.5 million for the three and nine months ended September 30, 2013, respectively. Total interest capitalized was $5.2 million and $15.4 million for the three and nine months ended September 30, 2014, respectively, and $6.6 million and $23.2 million for the three and nine months ended September 30, 2013, respectively. As each home in a capital project is completed and becomes available for lease-up, the Company ceases capitalization on the related portion and depreciation commences over the estimated useful life.
	In October 2012, Hurricane Sandy hit the East Coast, affecting three of the Company’s operating communities located in New York City. The properties suffered some physical damage, and were closed to residents for a period following the hurricane. The Company had insurance policies that provided coverage for property damage and business interruption, subject to applicable retentions.
	During the three and nine months ended September 30, 2013, the Company recorded $6.5 million and $12.3 million, respectively, of insurance recoveries related to the business interruption and other losses associated with Hurricane Sandy. In 2014, the Company recorded a $500,000 casualty-related loss for one property damaged during an earthquake in California. These recoveries/charges are included in Casualty-related (recoveries)/charges, net on the Consolidated Statements of Operations.

Real_Estate_Owned_UNITED_DOMIN

Real Estate Owned (UNITED DOMINION REALTY, L.P.)	9 Months Ended
	Sep. 30, 2014
Entity Information [Line Items]	'
REAL ESTATE OWNED	'
	REAL ESTATE OWNED
	Real estate assets owned by the Company consist of income producing operating properties, properties under development, land held for future development, and sold or held for disposition properties. As of September 30, 2014, the Company owned and consolidated 141 communities in 10 states plus the District of Columbia totaling 40,477 apartment homes. The following table summarizes the carrying amounts for our real estate owned (at cost) as of September 30, 2014 and December 31, 2013 (dollars in thousands):
		September 30,			December 31, 2013
		2014
	Land and land improvements	$	1,955,007		$	1,847,127
	Depreciable property — held and used:
	Building, improvements, and furniture, fixtures and equipment	6,151,677			5,876,717
	Under development:
	Land and land improvements	47,038			110,769
	Building, improvements, and furniture, fixtures and equipment	274,569			356,644
	Real estate held for disposition:
	Land and land improvements	—			10,751
	Building, improvements, and furniture, fixtures and equipment	—			5,969
	Real estate owned	8,428,291			8,207,977
	Accumulated depreciation	(2,379,033		)	(2,208,794		)
	Real estate owned, net	$	6,049,258		$	5,999,183
	During the nine months ended September 30, 2014, the Company sold six communities with a total of 1,904 apartment homes, an adjacent parcel of land, and one operating property for gross proceeds of $237.7 million, resulting in net proceeds of $233.9 million and a total gain (net of tax) of $82.4 million. A portion of the sale proceeds was designated for tax-deferred exchanges under Section 1031 of the Internal Revenue Code and was used to fund acquisitions of real estate as discussed below. Gains (net of tax) of $82.3 million are included in Gain/(loss) on sale of real estate owned, net of tax on the Consolidated Statements of Operations. The remaining gains (net of tax) of $0.1 million related to the sale of one operating property, which was classified as held for disposition prior to the Company’s adoption of ASU 2014-08 (as described in Note 2, Significant Accounting Policies and Note 4, Discontinued Operations), and, therefore, was included in Income/(loss) from discontinued operations, net of tax on the Consolidated Statements of Operations.
	In January 2014, the Company acquired a fully-entitled land parcel for future development located in Huntington Beach, California for $77.8 million. In the third quarter of 2014, the Company acquired two communities, located in Seattle, Washington and Kirkland, Washington, with a total of 358 apartment homes for $45.5 million and $75.2 million, respectively. The three acquisitions during the nine months ended September 30, 2014 were accomplished through tax-deferred exchanges under Section 1031 of the Internal Revenue Code.
	There were no sales during the nine months ended September 30, 2013.
	Predevelopment, development, and redevelopment projects and related costs are capitalized and reported on the Consolidated Balance Sheets as Total real estate owned, net of accumulated depreciation. The Company capitalizes costs directly related to the predevelopment, development, and redevelopment of a capital project, which include, but are not limited to, interest, real estate taxes, insurance, and allocated development and redevelopment overhead related to support costs for personnel working on the capital projects. We use our professional judgment in determining whether such costs meet the criteria for capitalization or must be expensed as incurred. These costs are capitalized only during the period in which activities necessary to ready an asset for its intended use are in progress and such costs are incremental and identifiable to a specific activity to get the asset ready for its intended use. These costs, excluding the direct costs of development and redevelopment and capitalized interest, were $1.7 million and $7.2 million for the three and nine months ended September 30, 2014, respectively, and $2.4 million and $8.5 million for the three and nine months ended September 30, 2013, respectively. Total interest capitalized was $5.2 million and $15.4 million for the three and nine months ended September 30, 2014, respectively, and $6.6 million and $23.2 million for the three and nine months ended September 30, 2013, respectively. As each home in a capital project is completed and becomes available for lease-up, the Company ceases capitalization on the related portion and depreciation commences over the estimated useful life.
	In October 2012, Hurricane Sandy hit the East Coast, affecting three of the Company’s operating communities located in New York City. The properties suffered some physical damage, and were closed to residents for a period following the hurricane. The Company had insurance policies that provided coverage for property damage and business interruption, subject to applicable retentions.
	During the three and nine months ended September 30, 2013, the Company recorded $6.5 million and $12.3 million, respectively, of insurance recoveries related to the business interruption and other losses associated with Hurricane Sandy. In 2014, the Company recorded a $500,000 casualty-related loss for one property damaged during an earthquake in California. These recoveries/charges are included in Casualty-related (recoveries)/charges, net on the Consolidated Statements of Operations.
United Dominion Reality L.P. [Member]	'
Entity Information [Line Items]	'
REAL ESTATE OWNED	'
	REAL ESTATE OWNED
	Real estate assets owned by the Operating Partnership consists of income producing operating properties, properties under development, land held for future development, and sold or held for disposition properties. As of September 30, 2014, the Operating Partnership owned and consolidated 67 communities in nine states plus the District of Columbia totaling 20,753 apartment homes. The following table summarizes the carrying amounts for our real estate owned (at cost) as of September 30, 2014 and December 31, 2013 (dollars in thousands):
		September 30,			December 31, 2013
		2014
	Land	$	998,797		$	1,004,447
	Depreciable property — held and used:
	Buildings, improvements, and furniture, fixture and equipment	3,100,598			3,103,970
	Under development:
	Land	9,447			9,447
	Buildings, improvements, and furniture, fixture and equipment	110,381			70,616
	Real estate owned	4,219,223			4,188,480
	Accumulated depreciation	(1,358,123		)	(1,241,574		)
	Real estate owned, net	$	2,861,100		$	2,946,906
	The Operating Partnership did not have any acquisitions during the nine months ended September 30, 2014 and 2013.
	During the nine months ended September 30, 2014, the Operating Partnership sold one community and an adjacent parcel of land in San Diego, CA for gross proceeds of $48.7 million, resulting in a $24.4 million gain and net proceeds of $47.9 million. The Operating Partnership also recorded a gain of $16.3 million in connection with the sale of one community in Tampa, Florida, which was previously deferred. The total gains of $40.7 million are included in Gain/(loss) on sale of real estate owned on the Consolidated Statements of Operations.
	There were no real estate sales during the three and nine months ended September 30, 2013.
	Predevelopment, development, and redevelopment projects and related costs are capitalized and reported on the Consolidated Balance Sheets as Total real estate owned, net of accumulated depreciation. The Operating Partnership capitalizes costs directly related to the predevelopment, development, and redevelopment of a capital project, which include, but are not limited to, interest, real estate taxes, insurance, and allocated development and redevelopment overhead related to support costs for personnel working on the capital projects. We use our professional judgment in determining whether such costs meet the criteria for capitalization or must be expensed as incurred. These costs are capitalized only during the period in which activities necessary to ready an asset for its intended use are in progress and such costs are incremental and identifiable to a specific activity to get the asset ready for its intended use. These costs, excluding the direct costs of development and redevelopment and capitalized interest, were $496,000 and $1.8 million for the three and nine months ended September 30, 2014, respectively, and $618,000 and $2.0 million for the three and nine months ended September 30, 2013, respectively. Total interest capitalized was $805,000 and $2.8 million during the three and nine months ended September 30, 2014, respectively, and $1.7 million and $4.4 million during the three and nine months ended September 30, 2013, respectively. As each home in a capital project is completed and becomes available for lease-up, the Company ceases capitalization on the related portion and depreciation commences over the estimated useful life.
	In October 2012, Hurricane Sandy hit the East Coast, affecting two of the Operating Partnership’s operating communities located in New York City. The properties suffered some physical damage, and were closed to residents for a period following the hurricane. The Operating Partnership had insurance policies that provided coverage for property damage and business interruption, subject to applicable retentions.
	During the three and nine months ended September 30, 2013, the Operating Partnership recorded $3.8 million and $8.1 million, respectively, of insurance recoveries related to the business interruption and other losses associated with Hurricane Sandy. During the nine months ended September 30, 2014, we recorded a $500,000 casualty-related loss for one property damaged during an earthquake in California. These recoveries/charges were included in Casualty-related (recoveries)/charges, net on the Consolidated Statements of Operations.

Discontinued_Operations

Discontinued Operations	9 Months Ended
	Sep. 30, 2014
Discontinued Operations and Disposal Groups [Abstract]	'
DISCONTINUED OPERATIONS	'
	DISCONTINUED OPERATIONS
	Effective January 1, 2014, UDR prospectively adopted ASU No. 2014-08, Reporting Discontinued Operations and Disclosures of Disposals of Components of an Entity, for all communities not previously sold or classified as held for sale. The standard had a material impact on the Company’s consolidated financial statements. As a result of adopting the ASU, during the three and nine months ended September 30, 2014, gains (net of tax) of $31.3 million and $81.2 million, respectively, from disposition of real estate, excluding a $1.1 million gain related to the sale of land during the first quarter of 2014, are included in Gain/(loss) on sale of real estate owned, net of tax on the Consolidated Statements of Operations rather than in Income/(loss) from discontinued operations, net of tax on the Consolidated Statements of Operations.
	Prior to the prospective adoption of ASU 2014-08, FASB Accounting Standards Codification ("ASC") Subtopic 205-20 required, among other things, that the primary assets and liabilities and the results of operations of UDR’s real properties that have been sold or are held for disposition, be classified as discontinued operations and segregated in UDR’s Consolidated Statements of Operations and Consolidated Balance Sheets. Consequently, the primary assets and liabilities and the net operating results of those properties sold or classified as held for disposition prior to January 1, 2014 are accounted for as discontinued operations for all periods presented. This presentation does not have an impact on net income available to common stockholders; it only results in the reclassification of the operating results within the Consolidated Statements of Operations for the periods ended September 30, 2014 and 2013.
	In July 2014, the Company sold one operating property that was classified as held for disposition prior to the adoption of ASU 2014-08 and, therefore, met the requirements to be reported as a discontinued operation. The sale of this property resulted in an immaterial gain (net of tax) of less than $0.1 million. The gain (net of tax) and operating results of the property for the three and nine months ended September 30, 2014 and 2013, are included in Income/(loss) from discontinued operations, net of tax on the Consolidated Statements of Operations.
	In December 2013, the Company sold two communities with 914 apartments in the Sacramento market. The operating results related to these communities for the three and nine months ended September 30, 2013 are included in Income/(loss) from discontinued operations, net of tax on the Consolidated Statements of Operations.
	The following is a summary of income/(loss) from discontinued operations, net of tax for the three and nine months ended September 30, 2014 and 2013 (dollars in thousands):
		Three Months Ended September 30,					Nine Months Ended September 30,
		2014			2013		2014			2013
	Rental income	$	21		$	2,462	$	147		$	7,130
	Rental expenses	11			970		225			2,733
	Property management	1			68		4			196
	Real estate depreciation	—			528		—			1,608
	Other operating expenses	3			12		21			26
	Income/(loss) attributable to disposed properties and assets held for sale	6			884		(103		)	2,567
	Net gain/(loss) on the sale of depreciable properties	75			—		75			—
	Income tax benefit/(expense)	(2		)	—		38			—
	Income/(loss) from discontinued operations, net of tax	$	79		$	884	$	10		$	2,567
	Income/(loss) from discontinued operations attributable to UDR, Inc.	$	73		$	852	$	6		$	2,475

Discontinued_Operations_UNITED

Discontinued Operations (UNITED DOMINION REALTY, L.P.)	9 Months Ended
	Sep. 30, 2014
Entity Information [Line Items]	'
DISCONTINUED OPERATIONS	'
	DISCONTINUED OPERATIONS
	Effective January 1, 2014, UDR prospectively adopted ASU No. 2014-08, Reporting Discontinued Operations and Disclosures of Disposals of Components of an Entity, for all communities not previously sold or classified as held for sale. The standard had a material impact on the Company’s consolidated financial statements. As a result of adopting the ASU, during the three and nine months ended September 30, 2014, gains (net of tax) of $31.3 million and $81.2 million, respectively, from disposition of real estate, excluding a $1.1 million gain related to the sale of land during the first quarter of 2014, are included in Gain/(loss) on sale of real estate owned, net of tax on the Consolidated Statements of Operations rather than in Income/(loss) from discontinued operations, net of tax on the Consolidated Statements of Operations.
	Prior to the prospective adoption of ASU 2014-08, FASB Accounting Standards Codification ("ASC") Subtopic 205-20 required, among other things, that the primary assets and liabilities and the results of operations of UDR’s real properties that have been sold or are held for disposition, be classified as discontinued operations and segregated in UDR’s Consolidated Statements of Operations and Consolidated Balance Sheets. Consequently, the primary assets and liabilities and the net operating results of those properties sold or classified as held for disposition prior to January 1, 2014 are accounted for as discontinued operations for all periods presented. This presentation does not have an impact on net income available to common stockholders; it only results in the reclassification of the operating results within the Consolidated Statements of Operations for the periods ended September 30, 2014 and 2013.
	In July 2014, the Company sold one operating property that was classified as held for disposition prior to the adoption of ASU 2014-08 and, therefore, met the requirements to be reported as a discontinued operation. The sale of this property resulted in an immaterial gain (net of tax) of less than $0.1 million. The gain (net of tax) and operating results of the property for the three and nine months ended September 30, 2014 and 2013, are included in Income/(loss) from discontinued operations, net of tax on the Consolidated Statements of Operations.
	In December 2013, the Company sold two communities with 914 apartments in the Sacramento market. The operating results related to these communities for the three and nine months ended September 30, 2013 are included in Income/(loss) from discontinued operations, net of tax on the Consolidated Statements of Operations.
	The following is a summary of income/(loss) from discontinued operations, net of tax for the three and nine months ended September 30, 2014 and 2013 (dollars in thousands):
		Three Months Ended September 30,					Nine Months Ended September 30,
		2014			2013		2014			2013
	Rental income	$	21		$	2,462	$	147		$	7,130
	Rental expenses	11			970		225			2,733
	Property management	1			68		4			196
	Real estate depreciation	—			528		—			1,608
	Other operating expenses	3			12		21			26
	Income/(loss) attributable to disposed properties and assets held for sale	6			884		(103		)	2,567
	Net gain/(loss) on the sale of depreciable properties	75			—		75			—
	Income tax benefit/(expense)	(2		)	—		38			—
	Income/(loss) from discontinued operations, net of tax	$	79		$	884	$	10		$	2,567
	Income/(loss) from discontinued operations attributable to UDR, Inc.	$	73		$	852	$	6		$	2,475
United Dominion Reality L.P. [Member]	'
Entity Information [Line Items]	'
DISCONTINUED OPERATIONS	'
	DISCONTINUED OPERATIONS
	Effective January 1, 2014, UDR prospectively adopted ASU No. 2014-08, Reporting Discontinued Operations and Disclosures of Disposals of Components of an Entity, for all communities not previously sold or classified as held for sale. The standard had a material impact on the Company’s consolidated financial statements. As a result of adopting the ASU, during the three and nine months ended September 30, 2014, net gains of zero and $39.6 million, respectively, from disposition of real estate, excluding a $1.1 million gain related to the sale of land during the first quarter of 2014, were included in Gain/(loss) on sale of real estate owned on the Consolidated Statements of Operations rather than in Income/(loss) from discontinued operations on the Consolidated Statements of Operations.
	Prior to the prospective adoption of ASU 2014-08, FASB ASC Subtopic 205-20, required, among other things, that the primary assets and liabilities and the results of operations of UDR’s real properties that have been sold or are held for disposition, be classified as discontinued operations and segregated in UDR’s Consolidated Statements of Operations and Consolidated Balance Sheets. Consequently, the primary assets and liabilities and the net operating results of those properties sold or classified as held for disposition prior to January 1, 2014 are accounted for as discontinued operations for all periods presented. This presentation does not have an impact on net income available to common stockholders, it only results in the reclassification of the operating results within the Consolidated Statements of Operations for the periods ended September 30, 2014 and 2013.
	In 2013, the Company sold two communities with 914 apartment homes in the Sacramento market. The operating results related to these communities for the three and nine months ended September 30, 2013 are included in Income/(loss) from discontinued operations on the Consolidated Statements of Operations.
	The following is a summary of income/(loss) from discontinued operations for the three and nine months ended September 30, 2014 and 2013 (dollars in thousands):
		Three Months Ended September 30,					Nine Months Ended September 30,
		2014			2013		2014			2013
	Rental income	$	—		$	2,438	$	—		$	7,016
	Rental expenses	—			869		—			2,467
	Property management	—			67		—			193
	Real estate depreciation and amortization	—			524		—			1,590
	Income/(loss) from discontinued operations	$	—		$	978	$	—		$	2,766
	Income/(loss) from discontinued operations attributable to UDR, Inc.	$	—		$	978	$	—		$	2,766

Joint_Ventures

Joint Ventures	9 Months Ended
	Sep. 30, 2014
Schedule of Equity Method Investments [Line Items]	'
Equity Method Investments and Joint Ventures Disclosure [Text Block]	'
	JOINT VENTURES AND PARTNERSHIPS
	UDR has entered into joint ventures and partnerships with unrelated third parties to acquire real estate assets that are either consolidated and included in Real estate owned on the Consolidated Balance Sheets or are accounted for under the equity method of accounting, and are included in Investment in and advances to unconsolidated joint ventures, net on the Consolidated Balance Sheets. The Company consolidates the entities that we control as well as any variable interest entity where we are the primary beneficiary. In addition, the Company consolidates any joint venture or partnership in which we are the general partner or managing member and the third party does not have the ability to substantively participate in the decision-making process nor the ability to remove us as general partner or managing member without cause.
	UDR’s joint ventures and partnerships are funded with a combination of debt and equity. Our losses are limited to our investment and except as noted below, the Company does not guarantee any debt, capital payout or other obligations associated with our joint ventures and partnerships.
	Consolidated Joint Ventures
	In December 2013, the Company consolidated its 95%/5% development joint ventures: 13th and Market JV in San Diego, CA and Domain College Park JV in Metropolitan D.C. The consolidation was due to the Company becoming the managing member of each of the joint ventures pursuant to amendments to the limited liability company agreement for each joint venture. In connection with the amendments, our partner received equity distributions reducing its capital account balances to zero, the Company replaced our partner as the managing member, and our partner no longer has the ability to substantively participate in the decision-making process, with only protective rights remaining. We accounted for the consolidations as asset acquisitions since the joint ventures were under development and not complete at the time of consolidation, resulting in no gain or loss upon consolidation and increasing our real estate owned by $129.4 million and our debt by $63.6 million. In addition pursuant to the amendments, the Company paid a non-refundable deposit to our partner in January 2014 of $2.0 million for each joint venture, or $4.0 million in total, for the right to exercise options in 2014 to acquire our partner’s upside participation in the joint ventures. The non-refundable deposits will be applied towards the future purchase price, which will be equivalent to our partner’s right to receive certain upside participation from the developments.
	Unconsolidated Joint Ventures and Partnerships
	The Company recognizes earnings or losses from our investments in unconsolidated joint ventures and partnerships consisting of our proportionate share of the net earnings or losses of the joint ventures and partnerships. In addition, we may earn fees for providing management services to the unconsolidated joint ventures and partnerships.
	The following table summarizes the Company’s investment in and advances to unconsolidated joint ventures and partnerships, net, which are accounted for under the equity method of accounting as of September 30, 2014 and December 31, 2013 (dollars in thousands):
	Joint Venture		Location of Properties		Number of Properties		Number of Apartment Homes		Investment at						UDR’s Ownership Interest
					30-Sep-14		30-Sep-14		September 30, 2014			December 31, 2013			September 30, 2014				December 31, 2013
	Operating and development:
	UDR/MetLife I (a)		Various		0 operating communities		—		$	—		$	40,336		—			%	13.2			%
					5 land parcels		N/A		5,364			7,161			4			%	4			%
	UDR/MetLife II (a)		Various		21 operating communities		4,642		436,805			327,926			50			%	50			%
	UDR/MetLife Vitruvian Park®		Addison, TX		2 operating communities		739		79,807			79,318			50			%	50			%
					1 non-stabilized community		391
					6 land parcels		N/A
	UDR/KFH		Washington, D.C.		3 operating communities		660		22,891			25,919			30			%	30			%
	Texas		Texas		8 operating communities		3,359		(25,624		)	(23,591		)	20			%	20			%
	Other UDR/MetLife Development Joint Ventures		Various		2 development communities (b)		828		87,376			36,313			51			%	51			%
					1 land parcel		N/A
	Investment in and advances to unconsolidated joint ventures, net, before participating loan investment								606,619			493,382
			Location		Interest Rate		Years To Maturity		Investment at						Income From Participating Loan Investment For
									September 30, 2014			December 31, 2013			Three Months Ended September 30					Nine Months Ended September 30
																2014	2013			2014	2013
	Participating loan investment:
	Steele Creek		Denver, CO		6.50%		3.1		43,822			14,273				$642	—			$1,419	—
	Total investment in and advances to unconsolidated joint ventures, net								$	650,441		$	507,655
	(a)	On March 31, 2014, the Company sold its minority ownership interests in two small operating communities located in Los Angeles, CA to MetLife for cash proceeds of $3.0 million, which resulted in an immaterial gain. On April 21, 2014, the Company increased its ownership interest in the remaining six operating communities in the UDR/MetLife I Joint Venture from 12% to 50%, and MetLife and the Company contributed these communities to the UDR/MetLife II Joint Venture. The Company paid MetLife $82.5 million for the additional ownership interests. The Company continues to manage the operating communities that were contributed to the UDR/MetLife II Joint Venture as well as the two operating communities in which it sold its minority ownership interests.
	In July 2014, the Company increased the ownership interest in two of these land sites to 50.1%. The remaining 49.9% continues to be held by our joint venture partner MetLife. The Company paid MetLife approximately $21.5 million for the additional ownership interests. As of September 30, 2014, the remaining assets in the UDR/MetLife I Joint Venture were comprised of five potential development land sites in which the Company has an average ownership interest of approximately 4%.
	(b)	The number of apartment homes for the communities under development presented in the table above is based on the projected number of total homes. As of September 30, 2014, no apartment homes had been completed in Other UDR/MetLife Development Joint Ventures.
	As of September 30, 2014 and December 31, 2013, the Company had deferred fees and deferred profit from the sale of properties to joint ventures or partnerships of $27.1 million and $25.4 million, respectively, which will be recognized through earnings over the weighted average life of the related properties, upon the disposition of the properties to a third party, or upon completion of certain development obligations.
	The Company recognized management fees for our management of the joint ventures and partnerships of $2.7 million and $8.3 million for the three and nine months ended September 30, 2014, respectively, and $2.8 million and $8.5 million during the three and nine months ended September 30, 2013, respectively, The management fees are included in Joint venture management and other fees on the Consolidated Statements of Operations.
	The Company may, in the future, make additional capital contributions to certain of our joint ventures and partnerships should additional capital contributions be necessary to fund acquisitions or operations.
	We evaluate our investments in unconsolidated joint ventures and partnerships when events or changes in circumstances indicate that there may be an other-than-temporary decline in value. We consider various factors to determine if a decrease in the value of the investment is other-than-temporary. The Company did not recognize any other-than-temporary decreases in the value of its investments in unconsolidated joint ventures or partnerships during the three and nine months ended September 30, 2014 and 2013.
	Combined summary balance sheets relating to all of the unconsolidated joint ventures and partnerships (not just our proportionate share) are presented below as of September 30, 2014 and December 31, 2013 (dollars in thousands):
		30-Sep-14				December 31, 2013
	Total real estate, net	$	3,012,380			$	3,124,178
	Cash and cash equivalents	40,656				41,792
	Other assets	37,903				32,234
	Total assets	$	3,090,939			$	3,198,204
	Amount due to UDR	$	10,856			$	12,187
	Third party debt	1,659,316				1,722,960
	Accounts payable and accrued liabilities	49,388				41,562
	Total liabilities	1,719,560				1,776,709
	Total equity	1,371,379				1,421,495
	Total liabilities and equity	$	3,090,939			$	3,198,204
	UDR’s investment in unconsolidated joint ventures	$	650,441			$	507,655
	Combined summary financial information relating to all of the unconsolidated joint ventures’ and partnerships’ operations (not just our proportionate share), is presented below for the three and nine months ended September 30, 2014 and 2013 (dollars in thousands):
		Three Months Ended September 30,							Nine Months Ended September 30,
		2014				2013			2014			2013
	Total revenues	$	63,449			$	61,198		$	187,340		$	166,796
	Property operating expenses	(24,769		)		(24,509		)	(74,324		)	(64,532		)
	Real estate depreciation and amortization	(24,525		)		(21,285		)	(73,727		)	(58,699		)
	Operating income/(loss)	14,155				15,404			39,289			43,565
	Interest expense	(18,879		)		(19,370		)	(56,745		)	(53,282		)
	Other income/(expense)	—				—			(190		)	4
	Gain/(loss) on sale of real estate	(113		)		—			(25,492		)	—
	Income/(loss) from discontinued operations	—				(806		)	14			(22,592		)
	Net income/(loss)	$	(4,837	)		$	(4,772	)	$	(43,124	)	$	(32,305	)
	UDR income/(loss) from unconsolidated entities	$	(939	)		$	(3,794	)	$	(4,932	)	$	(6,081	)

Secured_and_Unsecured_Debt

Secured and Unsecured Debt	9 Months Ended
	Sep. 30, 2014
Debt Disclosure [Abstract]	'
Debt Disclosure [Text Block]	'
	SECURED AND UNSECURED DEBT
	The following is a summary of our secured and unsecured debt at September 30, 2014 and December 31, 2013 (dollars in thousands):
		Principal Outstanding						For the Nine Months Ended September 30, 2014
								Weighted Average			Weighted Average		Number of Communities
		September 30, 2014			December 31, 2013			Interest Rate			Years to Maturity		Encumbered
	Secured Debt:
	Fixed Rate Debt
	Mortgage notes payable (a)	$	438,172		$	445,706		5.47	%		1.8		8
	Fannie Mae credit facilities (b)	623,754			626,667			4.99	%		4.3		22
	Total fixed rate secured debt	1,061,926			1,072,373			5.19	%		3.2		30
	Variable Rate Debt
	Mortgage notes payable	31,337			63,595			1.94	%		2.3		1
	Tax-exempt secured notes payable (c)	94,700			94,700			0.77	%		8.4		2
	Fannie Mae credit facilities (b)	211,409			211,409			1.58	%		5.8		7
	Total variable rate secured debt	337,446			369,704			1.39	%		6.2		10
	Total Secured Debt	1,399,372			1,442,077			4.27	%		4		40
	Unsecured Debt:
	Commercial Banks
	Borrowings outstanding under an unsecured credit facility due December 2017 (d) (f)	160,000			—			1.1	%		3.2
	Senior Unsecured Notes
	3.70% Medium-Term Notes due October 2020 (net of discounts of $48 and $54, respectively) (f)	299,952			299,946			3.7	%		6
	4.63% Medium-Term Notes due January 2022 (net of discounts of $2,613 and $2,882, respectively) (f)	397,387			397,118			4.63	%		7.3
	3.75% Medium-Term Notes due July 2024 (net of discount of $1,017) (e) (f)	298,983			—			3.75	%		9.8
	1.30% Term Notes due June 2018 (f)	35,000			35,000			1.3	%		3.7
	1.53% Term Notes due June 2018 (f)	100,000			65,000			1.53	%		3.7
	5.13% Medium-Term Notes due January 2014	—			184,000			—	%		—
	5.50% Medium-Term Notes due April 2014 (net of discount of $20)	—			128,480			—	%		—
	5.25% Medium-Term Notes due January 2015 (net of discounts of $37 and $134, respectively)	325,138			325,041			5.25	%		0.3
	5.25% Medium-Term Notes due January 2016	83,260			83,260			5.25	%		1.3
	2.17% Term Notes due June 2018 (f)	215,000			250,000			2.17	%		3.7
	8.50% Debentures due September 2024	15,644			15,644			8.5	%		10
	4.25% Medium-Term Notes due June 2018 (net of discounts of $1,572 and $1,893, respectively) (f)	298,428			298,107			4.25	%		3.7
	Other	28			30			N/A			N/A
	Total Unsecured Debt	2,228,820			2,081,626			3.8	%		4.9
	Total Debt	$	3,628,192		$	3,523,703		3.98	%		4.5
	Our secured debt instruments generally feature either monthly interest and principal or monthly interest-only payments with balloon payments due at maturity. For purposes of classification of the above table, variable rate debt with a derivative financial instrument designated as a cash flow hedge is deemed as fixed rate debt due to the Company having effectively established a fixed interest rate for the underlying debt instrument. Secured debt encumbers $2.3 billion or 26.9% of UDR’s total real estate owned based upon gross book value ($6.1 billion or 73.1% of UDR’s real estate owned based on gross book value is unencumbered) as of September 30, 2014.
	(a) At September 30, 2014, fixed rate mortgage notes payable are generally due in monthly installments of principal and interest and mature at various dates from December 2014 through May 2019 and carry interest rates ranging from 3.43% to 5.94%.
	The Company will from time to time acquire properties subject to fixed rate debt instruments. In those situations, the Company records the secured debt at its estimated fair value and amortizes any difference between the fair value and par to interest expense over the life of the underlying debt instrument. The Company had a reduction to interest expense based on the amortization of the fair market adjustment of debt assumed in the acquisition of properties of $1.3 million and $3.8 million during the three and nine months ended September 30, 2014, respectively, and $1.3 million and $3.8 million during the three and nine months ended September 30, 2013, respectively. The unamortized fair market adjustment was a net premium of $8.0 million and $11.8 million at September 30, 2014 and December 31, 2013, respectively.
	(b) UDR has three secured credit facilities with Fannie Mae with an aggregate commitment of $835.2 million at September 30, 2014. The Fannie Mae credit facilities are for terms of seven to ten years (maturing at various dates from May 2017 through July 2023) and bear interest at floating and fixed rates. At September 30, 2014, $623.8 million of the outstanding balance was fixed and had a weighted average interest rate of 4.99% and the remaining balance of $211.4 million had a weighted average variable interest rate of 1.58%.
	Further information related to these credit facilities is as follows (dollars in thousands):
		September 30, 2014			December 31, 2013
	Borrowings outstanding	$	835,163		$	838,076
	Weighted average borrowings during the period ended	836,305			839,597
	Maximum daily borrowings during the period ended	837,564			841,494
	Weighted average interest rate during the period ended	4.1		%	4.2		%
	Weighted average interest rate at the end of the period	4.1		%	4.1		%
	(c) The variable rate mortgage notes payable that secure tax-exempt housing bond issues mature in August 2019 and March 2032. Interest on these notes is payable in monthly installments. The variable rate mortgage notes have interest rates of 0.74% and 0.79% as of September 30, 2014.
	(d) As of September 30, 2014, the Company has a $900 million unsecured revolving credit facility that matures in December 2017. The credit facility has a six month extension option and contains an accordion feature that allows us to increase the facility to $1.45 billion. Based on the Company’s current credit rating, the credit facility carries an interest rate equal to LIBOR plus a spread of 100 basis points and a facility fee of 15 basis points.
	The following is a summary of short-term bank borrowings under UDR’s bank credit facility at September 30, 2014 and December 31, 2013 (dollars in thousands):
		September 30, 2014			December 31, 2013
	Total revolving credit facility	$	900,000		$	900,000
	Borrowings outstanding at end of period (1)	160,000			—
	Weighted average daily borrowings during the period ended	321,821			169,844
	Maximum daily borrowings during the period ended	625,000			372,000
	Weighted average interest rate during the period ended	1.2		%	1.2		%
	Interest rate at end of the period	1.1		%	1.3		%
	(1) Excludes $2.2 million of letters of credit at September 30, 2014 and December 31, 2013.
	(e) On June 26, 2014, the Company issued $300 million of 3.750% senior unsecured medium-term notes due July 1, 2024. Interest is payable semi-annually beginning on January 1, 2015. The notes were priced at 99.652% of the principal amount at issuance and had a discount of $1.0 million at September 30, 2014. The Company used the net proceeds to pay down borrowings outstanding on our $900 million unsecured credit facility and for general corporate purposes. The notes are fully and unconditionally guaranteed by the Operating Partnership.
	(f) The Operating Partnership is a guarantor at September 30, 2014 and December 31, 2013.
	The aggregate maturities, including amortizing principal payments of unsecured and secured debt, of total debt for the next five calendar years subsequent to September 30, 2014 are as follows (dollars in thousands):
	Year		Total Fixed Secured Debt			Total Variable Secured Debt			Total Secured Debt			Total Unsecured Debt (a)		Total Debt
	2014		$	37,835		$	—		$	37,835		$	—	$	37,835
	2015		197,359			—			197,359			323,874		521,233
2016		136,434			31,337			167,771			82,417		250,188
2017		177,955			65,000			242,955			160,000		402,955
2018		176,472			50,000			226,472			648,510		874,982
Thereafter		335,871			191,109			526,980			1,014,019		1,540,999
Total		$	1,061,926		$	337,446		$	1,399,372		$	2,228,820	$	3,628,192
(a) With the exception of the 1.30% Term Notes due June 2018 and the revolving credit facility which carry a variable interest rate, all unsecured debt carries fixed interest rates.
We were in compliance with the covenants of our debt instruments at September 30, 2014.

Debt_UNITED_DOMINION_REALTY_LP

Debt (UNITED DOMINION REALTY, L.P.)	9 Months Ended
	Sep. 30, 2014
Entity Information [Line Items]	'
DEBT	'
	SECURED AND UNSECURED DEBT
	The following is a summary of our secured and unsecured debt at September 30, 2014 and December 31, 2013 (dollars in thousands):
		Principal Outstanding						For the Nine Months Ended September 30, 2014
								Weighted Average			Weighted Average		Number of Communities
		September 30, 2014			December 31, 2013			Interest Rate			Years to Maturity		Encumbered
	Secured Debt:
	Fixed Rate Debt
	Mortgage notes payable (a)	$	438,172		$	445,706		5.47	%		1.8		8
	Fannie Mae credit facilities (b)	623,754			626,667			4.99	%		4.3		22
	Total fixed rate secured debt	1,061,926			1,072,373			5.19	%		3.2		30
	Variable Rate Debt
	Mortgage notes payable	31,337			63,595			1.94	%		2.3		1
	Tax-exempt secured notes payable (c)	94,700			94,700			0.77	%		8.4		2
	Fannie Mae credit facilities (b)	211,409			211,409			1.58	%		5.8		7
	Total variable rate secured debt	337,446			369,704			1.39	%		6.2		10
	Total Secured Debt	1,399,372			1,442,077			4.27	%		4		40
	Unsecured Debt:
	Commercial Banks
	Borrowings outstanding under an unsecured credit facility due December 2017 (d) (f)	160,000			—			1.1	%		3.2
	Senior Unsecured Notes
	3.70% Medium-Term Notes due October 2020 (net of discounts of $48 and $54, respectively) (f)	299,952			299,946			3.7	%		6
	4.63% Medium-Term Notes due January 2022 (net of discounts of $2,613 and $2,882, respectively) (f)	397,387			397,118			4.63	%		7.3
	3.75% Medium-Term Notes due July 2024 (net of discount of $1,017) (e) (f)	298,983			—			3.75	%		9.8
	1.30% Term Notes due June 2018 (f)	35,000			35,000			1.3	%		3.7
	1.53% Term Notes due June 2018 (f)	100,000			65,000			1.53	%		3.7
	5.13% Medium-Term Notes due January 2014	—			184,000			—	%		—
	5.50% Medium-Term Notes due April 2014 (net of discount of $20)	—			128,480			—	%		—
	5.25% Medium-Term Notes due January 2015 (net of discounts of $37 and $134, respectively)	325,138			325,041			5.25	%		0.3
	5.25% Medium-Term Notes due January 2016	83,260			83,260			5.25	%		1.3
	2.17% Term Notes due June 2018 (f)	215,000			250,000			2.17	%		3.7
	8.50% Debentures due September 2024	15,644			15,644			8.5	%		10
	4.25% Medium-Term Notes due June 2018 (net of discounts of $1,572 and $1,893, respectively) (f)	298,428			298,107			4.25	%		3.7
	Other	28			30			N/A			N/A
	Total Unsecured Debt	2,228,820			2,081,626			3.8	%		4.9
	Total Debt	$	3,628,192		$	3,523,703		3.98	%		4.5
	Our secured debt instruments generally feature either monthly interest and principal or monthly interest-only payments with balloon payments due at maturity. For purposes of classification of the above table, variable rate debt with a derivative financial instrument designated as a cash flow hedge is deemed as fixed rate debt due to the Company having effectively established a fixed interest rate for the underlying debt instrument. Secured debt encumbers $2.3 billion or 26.9% of UDR’s total real estate owned based upon gross book value ($6.1 billion or 73.1% of UDR’s real estate owned based on gross book value is unencumbered) as of September 30, 2014.
	(a) At September 30, 2014, fixed rate mortgage notes payable are generally due in monthly installments of principal and interest and mature at various dates from December 2014 through May 2019 and carry interest rates ranging from 3.43% to 5.94%.
	The Company will from time to time acquire properties subject to fixed rate debt instruments. In those situations, the Company records the secured debt at its estimated fair value and amortizes any difference between the fair value and par to interest expense over the life of the underlying debt instrument. The Company had a reduction to interest expense based on the amortization of the fair market adjustment of debt assumed in the acquisition of properties of $1.3 million and $3.8 million during the three and nine months ended September 30, 2014, respectively, and $1.3 million and $3.8 million during the three and nine months ended September 30, 2013, respectively. The unamortized fair market adjustment was a net premium of $8.0 million and $11.8 million at September 30, 2014 and December 31, 2013, respectively.
	(b) UDR has three secured credit facilities with Fannie Mae with an aggregate commitment of $835.2 million at September 30, 2014. The Fannie Mae credit facilities are for terms of seven to ten years (maturing at various dates from May 2017 through July 2023) and bear interest at floating and fixed rates. At September 30, 2014, $623.8 million of the outstanding balance was fixed and had a weighted average interest rate of 4.99% and the remaining balance of $211.4 million had a weighted average variable interest rate of 1.58%.
	Further information related to these credit facilities is as follows (dollars in thousands):
		September 30, 2014			December 31, 2013
	Borrowings outstanding	$	835,163		$	838,076
	Weighted average borrowings during the period ended	836,305			839,597
	Maximum daily borrowings during the period ended	837,564			841,494
	Weighted average interest rate during the period ended	4.1		%	4.2		%
	Weighted average interest rate at the end of the period	4.1		%	4.1		%
	(c) The variable rate mortgage notes payable that secure tax-exempt housing bond issues mature in August 2019 and March 2032. Interest on these notes is payable in monthly installments. The variable rate mortgage notes have interest rates of 0.74% and 0.79% as of September 30, 2014.
	(d) As of September 30, 2014, the Company has a $900 million unsecured revolving credit facility that matures in December 2017. The credit facility has a six month extension option and contains an accordion feature that allows us to increase the facility to $1.45 billion. Based on the Company’s current credit rating, the credit facility carries an interest rate equal to LIBOR plus a spread of 100 basis points and a facility fee of 15 basis points.
	The following is a summary of short-term bank borrowings under UDR’s bank credit facility at September 30, 2014 and December 31, 2013 (dollars in thousands):
		September 30, 2014			December 31, 2013
	Total revolving credit facility	$	900,000		$	900,000
	Borrowings outstanding at end of period (1)	160,000			—
	Weighted average daily borrowings during the period ended	321,821			169,844
	Maximum daily borrowings during the period ended	625,000			372,000
	Weighted average interest rate during the period ended	1.2		%	1.2		%
	Interest rate at end of the period	1.1		%	1.3		%
	(1) Excludes $2.2 million of letters of credit at September 30, 2014 and December 31, 2013.
	(e) On June 26, 2014, the Company issued $300 million of 3.750% senior unsecured medium-term notes due July 1, 2024. Interest is payable semi-annually beginning on January 1, 2015. The notes were priced at 99.652% of the principal amount at issuance and had a discount of $1.0 million at September 30, 2014. The Company used the net proceeds to pay down borrowings outstanding on our $900 million unsecured credit facility and for general corporate purposes. The notes are fully and unconditionally guaranteed by the Operating Partnership.
	(f) The Operating Partnership is a guarantor at September 30, 2014 and December 31, 2013.
	The aggregate maturities, including amortizing principal payments of unsecured and secured debt, of total debt for the next five calendar years subsequent to September 30, 2014 are as follows (dollars in thousands):
	Year		Total Fixed Secured Debt			Total Variable Secured Debt			Total Secured Debt			Total Unsecured Debt (a)		Total Debt
	2014		$	37,835		$	—		$	37,835		$	—	$	37,835
	2015		197,359			—			197,359			323,874		521,233
2016		136,434			31,337			167,771			82,417		250,188
2017		177,955			65,000			242,955			160,000		402,955
2018		176,472			50,000			226,472			648,510		874,982
Thereafter		335,871			191,109			526,980			1,014,019		1,540,999
Total		$	1,061,926		$	337,446		$	1,399,372		$	2,228,820	$	3,628,192
(a) With the exception of the 1.30% Term Notes due June 2018 and the revolving credit facility which carry a variable interest rate, all unsecured debt carries fixed interest rates.
We were in compliance with the covenants of our debt instruments at September 30, 2014.
United Dominion Reality L.P. [Member]	'
Entity Information [Line Items]	'
DEBT	'
	DEBT
	Our secured debt instruments generally feature either monthly interest and principal or monthly interest-only payments with balloon payments due at maturity. For purposes of classification in the following table, variable rate debt with a derivative financial instrument designated as a cash flow hedge is deemed as fixed rate debt due to the Operating Partnership having effectively established the fixed interest rate for the underlying debt instrument. Secured debt consists of the following as of September 30, 2014 and December 31, 2013 (dollars in thousands):
		Principal Outstanding						For the Nine Months Ended September 30, 2014
		September 30,			December 31, 2013			Weighted Average			Weighted Average		Number of Communities
		2014						Interest Rate			Years to Maturity		Encumbered
	Fixed Rate Debt
	Mortgage notes payable	$	380,506		$	386,803		5.46	%		1.8		5
	Fannie Mae credit facilities	378,709			379,003			4.71	%		4.7		10
	Total fixed rate secured debt	759,215			765,806			5.09	%		3.3		15
	Variable Rate Debt
	Tax-exempt secured note payable	27,000			27,000			0.74	%		17.5		1
	Fannie Mae credit facilities	142,058			142,059			1.88	%		7		5
	Total variable rate secured debt	169,058			169,059			1.7	%		8.7		6
	Total Secured Debt	$	928,273		$	934,865		4.47	%		4.3		21
	As of September 30, 2014, the General Partner had secured credit facilities with Fannie Mae with an aggregate commitment of $835.2 million with $835.2 million outstanding. The Fannie Mae credit facilities are for an initial term of seven to 10 years (maturing at various dates from May 2017 through July 2023) and bear interest at floating and fixed rates. At September 30, 2014, $623.8 million of the outstanding balance was fixed and had a weighted average interest rate of 4.99% and the remaining balance of $211.4 million on these facilities had a weighted average variable interest rate of 1.58%.
	The following information relates to the credit facilities allocated to the Operating Partnership (dollars in thousands):
		September 30,			December 31, 2013
		2014
	Borrowings outstanding	$	520,768		$	521,062
	Weighted average borrowings during the period ended	521,480			522,007
	Maximum daily borrowings during the period	522,265			523,187
	Weighted average interest rate during the period ended	3.9		%	4.2		%
	Interest rate at the end of the period	3.9		%	4.1		%
	The Operating Partnership may from time to time acquire properties subject to fixed rate debt instruments. In those situations, management will record the secured debt at its estimated fair value and amortize any difference between the fair value and par to interest expense over the life of the underlying debt instrument. The unamortized fair value adjustment of the fixed rate debt instruments on the Operating Partnership’s properties was a net premium of $7.1 million and $10.0 million at September 30, 2014 and December 31, 2013, respectively.
	Fixed Rate Debt
	Mortgage notes payable. Fixed rate mortgage notes payable are generally due in monthly installments of principal and interest and mature at various dates from December 2015 through May 2019 and carry interest rates ranging from 3.43% to 5.94%.
	Secured credit facilities. At September 30, 2014, the General Partner had borrowings against its fixed rate facilities of $623.8 million, of which $378.7 million was allocated to the Operating Partnership based on the ownership of the assets securing the debt. As of September 30, 2014, the fixed rate Fannie Mae credit facilities allocated to the Operating Partnership had a weighted average fixed interest rate of 4.71%.
	Variable Rate Debt
	Tax-exempt secured note payable. The variable rate mortgage note payable that secures tax-exempt housing bond issues matures March 2032. Interest on this note is payable in monthly installments. The mortgage note payable has an interest rate of 0.74% as of September 30, 2014.
	Secured credit facilities. At September 30, 2014, the General Partner had borrowings against its variable rate facilities of $211.4 million, of which $142.1 million was allocated to the Operating Partnership based on the ownership of the assets securing the debt. As of September 30, 2014, the variable rate borrowings under the Fannie Mae credit facilities allocated to the Operating Partnership had a weighted average floating interest rate of 1.88%.
	The aggregate maturities of the Operating Partnership’s secured debt due during each of the next five calendar years subsequent to September 30, 2014 are as follows (dollars in thousands):
			Fixed						Variable
	Year		Mortgage			Credit			Tax Exempt			Credit		Total
			Notes			Facilities			Notes Payable			Facilities
	2014		$	2,134		$	89		$	—		$	—	$	2,223
	2015		193,075			366			—			—		193,441
	2016		131,946			385			—			—		132,331
	2017		1,630			15,640			—			6,566		23,836
	2018		1,685			161,754			—			46,272		209,711
	Thereafter		50,036			200,475			27,000			89,220		366,731
	Total		$	380,506		$	378,709		$	27,000		$	142,058	$	928,273
	Guarantor on Unsecured Debt
	The Operating Partnership is a guarantor on the General Partner’s unsecured revolving credit facility with an aggregate borrowing capacity of $900 million, $250 million of term notes due June 2018, $100 million of term notes due June 2018, $300 million of medium-term notes due June 2018, $300 million of medium-term notes due October 2020, $400 million of medium-term notes due January 2022, and $300 million of medium-term notes due July 2024. As of September 30, 2014, the outstanding balance under the unsecured revolving credit facility was $160.0 million. As of December 31, 2013, there were no outstanding borrowings under the unsecured revolving credit facility.

IncomeLoss_Per_Share

Income/(Loss) Per Share	9 Months Ended
	Sep. 30, 2014
Earnings Per Share [Abstract]	'
EARNINGS/(LOSS) PER SHARE	'
	/(LOSS) PER SHARE
	The following table sets forth the computation of basic and diluted income/(loss) per share for the periods presented (dollars and shares in thousands, except per share data):
		Three Months Ended September 30,							Nine Months Ended September 30,
		2014			2013				2014			2013
	Numerator for income/(loss) per share:
	Income/(loss) from continuing operations	$	10,611		$	2,351			$	9,775		$	5,713
	Gain/(loss) on sale of real estate owned, net of tax	31,302			—				82,305			—
	(Income)/loss from continuing operations attributable to redeemable noncontrolling interests in the Operating Partnership	(1,441		)	(52		)		(3,167		)	(106		)
	(Income)/loss from continuing operations attributable to noncontrolling interests	4			37				(2		)	30
	Income/(loss) from continuing operations attributable to UDR, Inc.	40,476			2,336				88,911			5,637
	Distributions to preferred stockholders - Series E (Convertible)	(931		)	(931		)		(2,793		)	(2,793		)
	Income/(loss) from continuing operations attributable to common stockholders	$	39,545		$	1,405			$	86,118		$	2,844
	Income/(loss) from discontinued operations, net of tax	$	79		$	884			$	10		$	2,567
	(Income)/loss from discontinued operations attributable to redeemable noncontrolling interests in the Operating Partnership	(6		)	(32		)		(4		)	(92		)
	Income/(loss) from discontinued operations attributable to common stockholders	$	73		$	852			$	6		$	2,475
	Net income/(loss) attributable to common stockholders	$	39,618		$	2,257			$	86,124		$	5,319
	Denominator for income/(loss) per share:
	Weighted average common shares outstanding	252,891			250,744				251,860			250,663
	Non-vested restricted stock awards	(1,236		)	(759		)		(1,159		)	(701		)
	Denominator for basic income/(loss) per share	251,655			249,985				250,701			249,962
	Incremental shares issuable from assumed conversion of stock options and unvested restricted stock	2,077			1,469				1,974			1,477
	Denominator for diluted income/(loss) per share	253,732			251,454				252,675			251,439
	Income/(loss) per weighted average common share-basic:
	Income/(loss) from continuing operations attributable to common stockholders	$	0.16		$	0.01			$	0.34		$	0.01
	Income/(loss) from discontinued operations attributable to common stockholders	0			0				0			0.01
	Net income/(loss) attributable to common stockholders	$	0.16		$	0.01			$	0.34		$	0.02
	Income/(loss) per weighted average common share-diluted:
	Income/(loss) from continuing operations attributable to common stockholders	$	0.16		$	0.01			$	0.34		$	0.01
	Income/(loss) from discontinued operations attributable to common stockholders	0			0				0			0.01
	Net income/(loss) attributable to common stockholders	$	0.16		$	0.01			$	0.34		$	0.02
	Basic income/(loss) per common share is computed based upon the weighted average number of common shares outstanding. Diluted income/(loss) per share is computed based upon the weighted average number of common shares outstanding plus the common shares issuable from the assumed conversion of the OP Units, convertible preferred stock, stock options, and restricted stock. Only those instruments having a dilutive impact on our basic income/(loss) per share are included in diluted income/(loss) per share during the periods.
	The following table sets forth the additional shares of common stock outstanding by equity instrument if converted to common stock for each of the three and nine months ended September 30, 2014 and 2013 (shares in thousands):
			Three Months Ended September 30,					Nine Months Ended September 30,
			2014		2013			2014			2013
	OP Units		9,189		9,323			9,274			9,343
	Preferred stock		3,036		3,036			3,036			3,036
	Stock options and unvested restricted stock		2,077		1,469			1,974			1,477

IncomeLoss_Per_Operating_Partn

Income/(Loss) Per Operating Partnership Unit (UNITED DOMINION REALTY, L.P.) Income/(Loss) Per Operating Partnership Unit	9 Months Ended
	Sep. 30, 2014
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]	'
Earnings Per Share [Text Block]	'
	/(LOSS) PER SHARE
	The following table sets forth the computation of basic and diluted income/(loss) per share for the periods presented (dollars and shares in thousands, except per share data):
		Three Months Ended September 30,								Nine Months Ended September 30,
		2014				2013				2014				2013
	Numerator for income/(loss) per share:
	Income/(loss) from continuing operations	$	10,611			$	2,351			$	9,775			$	5,713
	Gain/(loss) on sale of real estate owned, net of tax	31,302				—				82,305				—
	(Income)/loss from continuing operations attributable to redeemable noncontrolling interests in the Operating Partnership	(1,441		)		(52		)		(3,167		)		(106		)
	(Income)/loss from continuing operations attributable to noncontrolling interests	4				37				(2		)		30
	Income/(loss) from continuing operations attributable to UDR, Inc.	40,476				2,336				88,911				5,637
	Distributions to preferred stockholders - Series E (Convertible)	(931		)		(931		)		(2,793		)		(2,793		)
	Income/(loss) from continuing operations attributable to common stockholders	$	39,545			$	1,405			$	86,118			$	2,844
	Income/(loss) from discontinued operations, net of tax	$	79			$	884			$	10			$	2,567
	(Income)/loss from discontinued operations attributable to redeemable noncontrolling interests in the Operating Partnership	(6		)		(32		)		(4		)		(92		)
	Income/(loss) from discontinued operations attributable to common stockholders	$	73			$	852			$	6			$	2,475
	Net income/(loss) attributable to common stockholders	$	39,618			$	2,257			$	86,124			$	5,319
	Denominator for income/(loss) per share:
	Weighted average common shares outstanding	252,891				250,744				251,860				250,663
	Non-vested restricted stock awards	(1,236		)		(759		)		(1,159		)		(701		)
	Denominator for basic income/(loss) per share	251,655				249,985				250,701				249,962
	Incremental shares issuable from assumed conversion of stock options and unvested restricted stock	2,077				1,469				1,974				1,477
	Denominator for diluted income/(loss) per share	253,732				251,454				252,675				251,439
	Income/(loss) per weighted average common share-basic:
	Income/(loss) from continuing operations attributable to common stockholders	$	0.16			$	0.01			$	0.34			$	0.01
	Income/(loss) from discontinued operations attributable to common stockholders	0				0				0				0.01
	Net income/(loss) attributable to common stockholders	$	0.16			$	0.01			$	0.34			$	0.02
	Income/(loss) per weighted average common share-diluted:
	Income/(loss) from continuing operations attributable to common stockholders	$	0.16			$	0.01			$	0.34			$	0.01
	Income/(loss) from discontinued operations attributable to common stockholders	0				0				0				0.01
	Net income/(loss) attributable to common stockholders	$	0.16			$	0.01			$	0.34			$	0.02
	Basic income/(loss) per common share is computed based upon the weighted average number of common shares outstanding. Diluted income/(loss) per share is computed based upon the weighted average number of common shares outstanding plus the common shares issuable from the assumed conversion of the OP Units, convertible preferred stock, stock options, and restricted stock. Only those instruments having a dilutive impact on our basic income/(loss) per share are included in diluted income/(loss) per share during the periods.
	The following table sets forth the additional shares of common stock outstanding by equity instrument if converted to common stock for each of the three and nine months ended September 30, 2014 and 2013 (shares in thousands):
			Three Months Ended September 30,						Nine Months Ended September 30,
			2014			2013			2014			2013
	OP Units		9,189			9,323			9,274			9,343
	Preferred stock		3,036			3,036			3,036			3,036
	Stock options and unvested restricted stock		2,077			1,469			1,974			1,477
United Dominion Reality L.P. [Member]	'
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]	'
Earnings Per Share [Text Block]	'
	/(LOSS) PER OPERATING PARTNERSHIP UNIT
	Basic income/(loss) per OP Unit is computed by dividing net income/(loss) attributable to general and limited partner unitholders by the weighted average number of general and limited partner units (including redeemable OP Units) outstanding during the period. Diluted income/(loss) per OP Unit reflects the potential dilution that could occur if securities or other contracts to issue OP Units were exercised or converted into OP Units or resulted in the issuance of OP Units and then shared in the income/(loss) of the Operating Partnership. For the three and nine months ended September 30, 2014 and 2013, there were no dilutive instruments outstanding, and therefore, diluted income/(loss) per OP Unit and basic income/(loss) per OP Unit are the same. See note 9, Capital Structure, for further discussion on redemption rights of OP Units.
	The following table sets forth the computation of basic and diluted income/(loss) per OP Unit for the periods presented (dollars in thousands, except per OP Unit data):
			Three Months Ended September 30,								Nine Months Ended September 30,
			2014				2013				2014				2013
	Numerator for income/(loss) per OP Unit — basic and diluted:
	Income/(loss) from continuing operations		$	8,875			$	10,072			$	23,606			$	26,278
	Gain/(loss) on sale of real estate owned		—				—				40,687				—
	(Income)/loss from continuing operations attributable to noncontrolling interests		(238		)		(39		)		(697		)		(151		)
	Income/(loss) from continuing operations attributable to OP unitholders		$	8,637			$	10,033			$	63,596			$	26,127
	Income/(loss) from discontinued operations		$	—			$	978			$	—			$	2,766
	(Income)/loss from discontinued operations attributable to noncontrolling interests		—				—				—				—
	Income/(loss) from discontinued operations attributable to OP unitholders		$	—			$	978			$	—			$	2,766
	Net income/(loss)		$	8,875			$	11,050			$	64,293			$	29,044
	Net (income)/loss attributable to noncontrolling interests		(238		)		(39		)		(697		)		(151		)
	Net income/(loss) attributable to OP unitholders		$	8,637			$	11,011			$	63,596			$	28,893
	Denominator for income/(loss) per OP Unit — basic and diluted:
	Weighted average OP Units outstanding — basic and diluted		183,279				184,281				183,279				184,281
	Income/(loss) per weighted average OP Unit — basic and diluted:
	Income/(loss) from continuing operations attributable to OP unitholders		$	0.05			0.05				$	0.35			$	0.14
	Income/(loss) from discontinued operations attributable to OP unitholders		$	—			$	0.01			$	—			$	0.02
	Net income/(loss) attributable to OP unitholders		$	0.05			0.06				$	0.35			$	0.16

Noncontrolling_Interests

Noncontrolling Interests	9 Months Ended
	Sep. 30, 2014
Noncontrolling Interest [Abstract]	'
NONCONTROLLING INTERESTS	'
	NONCONTROLLING INTERESTS
	Redeemable Noncontrolling Interests in the Operating Partnership
	Interests in the Operating Partnership held by limited partners are represented by OP Units. The income is allocated to holders of OP Units based upon net income attributable to common stockholders and the weighted average number of OP Units outstanding to total common shares plus OP Units outstanding during the period. Capital contributions, distributions, and profits and losses are allocated to noncontrolling interests in accordance with the terms of the individual partnership agreements.
	Limited partners have the right to require the Operating Partnership to redeem all or a portion of the OP Units held by the limited partners at a redemption price equal to and in the form of the Cash Amount as defined in the Amended and Restated Agreement of Limited Partnership of the Operating Partnership (the “Operating Partnership Agreement”), provided that such OP Units have been outstanding for at least one year. UDR, as the general partner of the Operating Partnership may, in its sole discretion, purchase the OP Units by paying to the limited partner either the Cash Amount or the REIT Share Amount (generally one share of common stock of the Company for each OP Unit), as defined in the Operating Partnership Agreement. Accordingly, the Company records the OP Units outside of permanent equity and reports the OP Units at their redemption value using the Company’s stock price at each balance sheet date.
	The following table sets forth redeemable noncontrolling interests in the Operating Partnership for the following period (dollars in thousands):
	Redeemable noncontrolling interests in the Operating Partnership, December 31, 2013	$	217,597
	Mark-to-market adjustment to redeemable noncontrolling interests in the Operating Partnership	40,771
	Conversion of OP Units to Common Stock	(4,318		)
	Net income/(loss) attributable to redeemable noncontrolling interests in the Operating Partnership	3,171
	Distributions to redeemable noncontrolling interests in the Operating Partnership	(7,570		)
	Allocation of other comprehensive income/(loss)	163
	Redeemable noncontrolling interests in the Operating Partnership, September 30, 2014	$	249,814
	The following sets forth net income/(loss) attributable to common stockholders and transfers from redeemable noncontrolling interests in the Operating Partnership for the following periods (dollars in thousands):
			Three Months Ended September 30,				Nine Months Ended September 30,
			2014		2013		2014		2013
	Net income/(loss) attributable to common stockholders		$	39,618	$	2,257	$	86,124	$	5,319
	Conversion of OP Units to UDR Common stock		4,127		—		4,318		1,711
	Change in equity from net income/(loss) attributable to common stockholders and conversion of OP Units to UDR Common Stock		$	43,745	$	2,257	$	90,442	$	7,030
	Noncontrolling Interests
	Noncontrolling interests represent interests of unrelated partners in certain consolidated affiliates, and are presented as part of equity in the Consolidated Balance Sheets since these interests are not redeemable. Net (income)/loss attributable to noncontrolling interests was $4,000 and $(2,000) during the three and nine months ended September 30, 2014, respectively, and

Related_Party_Transactions_UNI

Related Party Transactions (UNITED DOMINION REALTY, L.P.) (United Dominion Reality L.P. [Member])	9 Months Ended
	Sep. 30, 2014
United Dominion Reality L.P. [Member]	'
Entity Information [Line Items]	'
RELATED PARTY TRANSACTIONS	'
	RELATED PARTY TRANSACTIONS
	Payable/(Receivable) Due To/(From) the General Partner
	The Operating Partnership participates in the General Partner’s central cash management program, wherein all the Operating Partnership’s cash receipts are remitted to the General Partner and all cash disbursements are funded by the General Partner. In addition, other miscellaneous costs such as administrative expenses are incurred by the General Partner on behalf of the Operating Partnership. As a result of these various transactions between the Operating Partnership and the General Partner, the Operating Partnership had net payable/(receivable) balances of $795,000 and $(9.9) million at September 30, 2014 and December 31, 2013, respectively, which is reflected as an increase and a reduction of capital, respectively, on the Consolidated Balance Sheets.
	Allocation of General and Administrative Expenses
	The General Partner provides various general and administrative and other overhead services for the Operating Partnership including legal assistance, acquisitions analysis, marketing and advertising, and allocates these expenses to the Operating Partnership first on the basis of direct usage when identifiable, with the remainder allocated based on its pro-rata portion of UDR’s total apartment homes. The general and administrative expenses allocated to the Operating Partnership by UDR were $6.6 million and $20.5 million during the three and nine months ended September 30, 2014, respectively, and $6.5 million and $17.4 million during the three and nine months ended September 30, 2013, respectively, and are included in General and administrative on the Consolidated Statements of Operations. In the opinion of management, this method of allocation reflects the level of services received by the Operating Partnership from the General Partner.
	During the three and nine months ended September 30, 2014, the Operating Partnership incurred $3.2 million and $9.4 million, respectively, and during the three and nine months ended September 30, 2013 incurred $3.1 million and $9.1 million, respectively, of related party management fees related to a management agreement entered into in 2011 with wholly-owned subsidiaries of RE3. (See further discussion in paragraph below.) These related party management fees are initially recorded in General and administrative on the Consolidated Statements of Operations, and a portion related to management fees charged by the taxable REIT subsidiary (“TRS”) of the General Partner is reclassified to Property management on the Consolidated Statements of Operations. (See further discussion below.)
	Management Fee
	In 2011, the Operating Partnership entered into a management agreement with wholly owned subsidiaries of RE3. Under the management agreement, the Operating Partnership is charged a management fee equal to 2.75% of gross rental revenues, which is classified in Property management on the Consolidated Statements of Operations.
	Notes Payable to General Partner
	As of September 30, 2014 and December 31, 2013, the Operating Partnership had $88.7 million of unsecured notes payable to the General Partner at annual interest rates between 5.18% and 5.34%. Certain limited partners of the Operating Partnership have provided guarantees related to these notes payable. The guarantees were provided by the limited partners in conjunction with their contribution of properties to the Operating Partnership. The notes mature on August 31, 2021 and December 31, 2023 and interest payments are made monthly. The Operating Partnership recognized interest expense on the notes payable of $1.2 million and $3.5 million during the three and nine months ended September 30, 2014, respectively, and $267,000, and $801,000 during the three and nine months ended September 30, 2013, respectively.

Fair_Value_of_Derivatives_and_

Fair Value of Derivatives and Financial Instruments	9 Months Ended
	Sep. 30, 2014
Fair Value Disclosures [Abstract]	'
FAIR VALUE OF DERIVATIVES AND FINANCIAL INSTRUMENTS	'
	FAIR VALUE OF DERIVATIVES AND FINANCIAL INSTRUMENTS
	Fair value is based on the price that would be received to sell an asset or the exit price that would be paid to transfer a liability in an orderly transaction between market participants at the measurement date. A three-level valuation hierarchy prioritizes observable and unobservable inputs used to measure fair value. The fair value hierarchy consists of three broad levels, which are described below:
	•	Level 1 — Quoted prices in active markets for identical assets or liabilities that the entity has the ability to access.
	•	Level 2 — Observable inputs other than prices included in Level 1, such as quoted prices for similar assets and liabilities in active markets; quoted prices for identical or similar assets and liabilities in markets that are not active; or other inputs that are observable or can be corroborated with observable market data.
	•	Level 3 — Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets and liabilities. This includes certain pricing models, discounted cash flow methodologies and similar techniques that use significant unobservable inputs.
	The estimated fair values of the Company’s financial instruments either recorded or disclosed on a recurring basis as of September 30, 2014 and December 31, 2013 are summarized as follows (dollars in thousands):
						Fair Value at September 30, 2014, Using
		Total Carrying Amount in Statement of Financial Position at September 30, 2014		Fair Value Estimate at September 30, 2014		Quoted Prices in		Significant		Significant
						Active Markets		Other		Unobservable
						for Identical		Observable		Inputs
						Assets or		Inputs		(Level 3)
						Liabilities		(Level 2)
						(Level 1)
	Description:
	Notes receivable (a)	$	18,318	$	18,858	$	—	$	—	$	18,858
	Derivatives- Interest rate contracts (b)	299		299		—		299		—
	Total assets	$	18,617	$	19,157	$	—	$	299	$	18,858
	Derivatives- Interest rate contracts (b)	$	2,382	$	2,382	$	—	$	2,382	$	—
	Secured debt instruments- fixed rate: (c)
	Mortgage notes payable	438,172		451,582		—		—		451,582
	Fannie Mae credit facilities	623,754		655,035		—		—		655,035
	Secured debt instruments- variable rate: (c)
	Mortgage notes payable	31,337		31,337		—		—		31,337
	Tax-exempt secured notes payable	94,700		94,700		—		—		94,700
	Fannie Mae credit facilities	211,409		211,409		—		—		211,409
	Unsecured debt instruments: (c)
	Commercial bank	160,000		160,000		—		—		160,000
	Senior unsecured notes	2,068,820		2,136,468		—		—		2,136,468
	Total liabilities	$	3,630,574	$	3,742,913	$	—	$	2,382	$	3,740,531
	Redeemable noncontrolling interests in the Operating Partnership (d)	$	249,814	$	249,814	$	—	$	249,814	$	—
						Fair Value at December 31, 2013, Using
		Total Carrying Amount in Statement of Financial Position at December 31, 2013		Fair Value Estimate at December 31, 2013		Quoted Prices in		Significant		Significant
						Active Markets		Other		Unobservable
						for Identical		Observable		Inputs
						Assets or		Inputs		(Level 3)
						Liabilities		(Level 2)
						(Level 1)
	Description:
	Notes receivable (a)	$	83,033	$	83,833	$	—	$	—	$	83,833
	Total assets	$	83,033	$	83,833	$	—	$	—	$	83,833
	Derivatives- Interest rate contracts (b)	$	4,965	$	4,965	$	—	$	4,965	$	—
	Secured debt instruments- fixed rate: (c)
	Mortgage notes payable	445,706		466,375		—		—		466,375
	Fannie Mae credit facilities	626,667		661,094		—		—		661,094
	Secured debt instruments- variable rate: (c)
	Mortgage notes payable	63,595		63,595		—		—		63,595
	Tax-exempt secured notes payable	94,700		94,700		—		—		94,700
	Fannie Mae credit facilities	211,409		211,409		—		—		211,409
	Unsecured debt instruments: (c)
	Senior unsecured notes	2,081,626		2,149,003		—		—		2,149,003
	Total liabilities	$	3,528,668	$	3,651,141	$	—	$	4,965	$	3,646,176
	Redeemable noncontrolling interests in the Operating Partnership (d)	$	217,597	$	217,597	$	—	$	217,597	$	—
	(a)	See Note 2, Significant Accounting Policies.
	(b)	See Note 10, Derivatives and Hedging Activity.
	(c)	See Note 6, Secured and Unsecured Debt.
	(d)	See Note 8, Noncontrolling Interests.
	There were no transfers into or out of each of the levels of the fair value hierarchy for the periods ending September 30, 2014 and December 31, 2013.
	Financial Instruments Carried at Fair Value
	The fair values of interest rate swaps are determined using the market standard methodology of netting the discounted future fixed cash receipts (or payments) and the discounted expected variable cash payments (or receipts). The variable cash payments (or receipts) are based on an expectation of future interest rates (forward curves) derived from observable market interest rate curves. The fair values of interest rate options are determined using the market standard methodology of discounting the future expected cash receipts that would occur if variable interest rates rise above the strike rate of the caps. The variable interest rates used in the calculation of projected receipts on the cap are based on an expectation of future interest rates derived from observable market interest rate curves and volatilities.
	The Company incorporates credit valuation adjustments to appropriately reflect both its own nonperformance risk and the respective counterparty’s nonperformance risk in the fair value measurements. In adjusting the fair value of its derivative contracts for the effect of nonperformance risk, the Company has considered the impact of netting and any applicable credit enhancements, such as collateral postings, thresholds, mutual puts, and guarantees.
	Although the Company has determined that the majority of the inputs used to value its derivatives fall within Level 2 of the fair value hierarchy, the credit valuation adjustments associated with its derivatives utilize Level 3 inputs, such as estimates of current credit spreads to evaluate the likelihood of default by itself and its counterparties. However, as of September 30, 2014 and December 31, 2013, the Company has assessed the significance of the impact of the credit valuation adjustments on the overall valuation of its derivative positions and has determined that the credit valuation adjustments are not significant to the overall valuation of its derivatives. As a result, the Company has determined that its derivative valuations in their entirety are classified in Level 2 of the fair value hierarchy. In conjunction with the FASB’s fair value measurement guidance, the Company made an accounting policy election to measure the credit risk of its derivative financial instruments that are subject to master netting agreements on a net basis by counterparty portfolio.
	Redeemable noncontrolling interests in the Operating Partnership have a redemption feature and are marked to their redemption value. The redemption value is based on the fair value of the Company’s common stock at the redemption date, and therefore, is calculated based on the fair value of the Company’s common stock at the balance sheet date. Since the valuation is based on observable inputs such as quoted prices for similar instruments in active markets, redeemable noncontrolling interests in the Operating Partnership are classified as Level 2.
	Financial Instruments Not Carried at Fair Value
At September 30, 2014, the fair values of cash and cash equivalents, restricted cash, accounts receivable, prepaids, real estate taxes payable, accrued interest payable, security deposits and prepaid rent, distributions payable and accounts payable approximated their carrying values because of the short term nature of these instruments. The estimated fair values of other financial instruments were determined by the Company using available market information and appropriate valuation methodologies. Considerable judgment is necessary to interpret market data and develop estimated fair values. Accordingly, the estimates presented herein are not necessarily indicative of the amounts the Company would realize on the disposition of the financial instruments. The use of different market assumptions or estimation methodologies may have a material effect on the estimated fair value amounts.
We estimate the fair value of our notes receivable and debt instruments by discounting the remaining cash flows of the debt instrument at a discount rate equal to the replacement market credit spread plus the corresponding treasury yields. Factors considered in determining a replacement market credit spread include general market conditions, borrower specific credit spreads, time remaining to maturity, loan-to-value ratios and collateral quality, where applicable (Level 3).
We record impairment losses on long-lived assets used in operations when events and circumstances indicate that the assets might be impaired and the undiscounted cash flows estimated to be generated by the future operation and disposition of those assets are less than the net book value of those assets. Our cash flow estimates are based upon historical results adjusted to reflect our best estimate of future market and operating conditions and our estimated holding periods. The net book value of impaired assets is reduced to fair value. Our estimates of fair value represent our best estimate based upon Level 3 inputs such as industry trends and reference to market rates and transactions.
We consider various factors to determine if a decrease in the value of our investment in and advances to unconsolidated joint ventures, net is other-than-temporary. These factors include, but are not limited to, age of the venture, our intent and ability to retain our investment in the entity, the financial condition and long-term prospects of the entity, and the relationships with the other joint venture partners and its lenders. Based on the significance of the unobservable inputs, we classify these fair value measurements within Level 3 of the valuation hierarchy. The Company did not incur any other-than-temporary decrease in the value of its investments in unconsolidated joint ventures during the three and nine months ended September 30, 2014 and 2013.
After determining an other-than-temporary decrease in the value of an equity method investment has occurred, we estimate the fair value of our investment by estimating the proceeds we would receive upon a hypothetical liquidation of the investment at the date of measurement. Inputs reflect management’s best estimate of what market participants would use in pricing the investment giving consideration to the terms of the joint venture agreement and the estimated discounted future cash flows to be generated from the underlying joint venture assets. The inputs and assumptions utilized to estimate the future cash flows of the underlying assets are based upon the Company’s evaluation of the economy, market trends, operating results, and other factors, including judgments regarding costs to complete any construction activities, lease up and occupancy rates, rental rates, inflation rates, capitalization rates utilized to estimate the projected cash flows at the disposition, and discount rates.

Fair_Value_of_Derivatives_and_1

Fair Value of Derivatives and Financial Instruments (UNITED DOMINION REALTY, L.P.)	9 Months Ended
	Sep. 30, 2014
Entity Information [Line Items]	'
FAIR VALUE OF DERIVATIVES AND FINANCIAL INSTRUMENTS	'
	FAIR VALUE OF DERIVATIVES AND FINANCIAL INSTRUMENTS
	Fair value is based on the price that would be received to sell an asset or the exit price that would be paid to transfer a liability in an orderly transaction between market participants at the measurement date. A three-level valuation hierarchy prioritizes observable and unobservable inputs used to measure fair value. The fair value hierarchy consists of three broad levels, which are described below:
	•	Level 1 — Quoted prices in active markets for identical assets or liabilities that the entity has the ability to access.
	•	Level 2 — Observable inputs other than prices included in Level 1, such as quoted prices for similar assets and liabilities in active markets; quoted prices for identical or similar assets and liabilities in markets that are not active; or other inputs that are observable or can be corroborated with observable market data.
	•	Level 3 — Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets and liabilities. This includes certain pricing models, discounted cash flow methodologies and similar techniques that use significant unobservable inputs.
	The estimated fair values of the Company’s financial instruments either recorded or disclosed on a recurring basis as of September 30, 2014 and December 31, 2013 are summarized as follows (dollars in thousands):
						Fair Value at September 30, 2014, Using
		Total Carrying Amount in Statement of Financial Position at September 30, 2014		Fair Value Estimate at September 30, 2014		Quoted Prices in		Significant		Significant
						Active Markets		Other		Unobservable
						for Identical		Observable		Inputs
						Assets or		Inputs		(Level 3)
						Liabilities		(Level 2)
						(Level 1)
	Description:
	Notes receivable (a)	$	18,318	$	18,858	$	—	$	—	$	18,858
	Derivatives- Interest rate contracts (b)	299		299		—		299		—
	Total assets	$	18,617	$	19,157	$	—	$	299	$	18,858
	Derivatives- Interest rate contracts (b)	$	2,382	$	2,382	$	—	$	2,382	$	—
	Secured debt instruments- fixed rate: (c)
	Mortgage notes payable	438,172		451,582		—		—		451,582
	Fannie Mae credit facilities	623,754		655,035		—		—		655,035
	Secured debt instruments- variable rate: (c)
	Mortgage notes payable	31,337		31,337		—		—		31,337
	Tax-exempt secured notes payable	94,700		94,700		—		—		94,700
	Fannie Mae credit facilities	211,409		211,409		—		—		211,409
	Unsecured debt instruments: (c)
	Commercial bank	160,000		160,000		—		—		160,000
	Senior unsecured notes	2,068,820		2,136,468		—		—		2,136,468
	Total liabilities	$	3,630,574	$	3,742,913	$	—	$	2,382	$	3,740,531
	Redeemable noncontrolling interests in the Operating Partnership (d)	$	249,814	$	249,814	$	—	$	249,814	$	—
						Fair Value at December 31, 2013, Using
		Total Carrying Amount in Statement of Financial Position at December 31, 2013		Fair Value Estimate at December 31, 2013		Quoted Prices in		Significant		Significant
						Active Markets		Other		Unobservable
						for Identical		Observable		Inputs
						Assets or		Inputs		(Level 3)
						Liabilities		(Level 2)
						(Level 1)
	Description:
	Notes receivable (a)	$	83,033	$	83,833	$	—	$	—	$	83,833
	Total assets	$	83,033	$	83,833	$	—	$	—	$	83,833
	Derivatives- Interest rate contracts (b)	$	4,965	$	4,965	$	—	$	4,965	$	—
	Secured debt instruments- fixed rate: (c)
	Mortgage notes payable	445,706		466,375		—		—		466,375
	Fannie Mae credit facilities	626,667		661,094		—		—		661,094
	Secured debt instruments- variable rate: (c)
	Mortgage notes payable	63,595		63,595		—		—		63,595
	Tax-exempt secured notes payable	94,700		94,700		—		—		94,700
	Fannie Mae credit facilities	211,409		211,409		—		—		211,409
	Unsecured debt instruments: (c)
	Senior unsecured notes	2,081,626		2,149,003		—		—		2,149,003
	Total liabilities	$	3,528,668	$	3,651,141	$	—	$	4,965	$	3,646,176
	Redeemable noncontrolling interests in the Operating Partnership (d)	$	217,597	$	217,597	$	—	$	217,597	$	—
	(a)	See Note 2, Significant Accounting Policies.
	(b)	See Note 10, Derivatives and Hedging Activity.
	(c)	See Note 6, Secured and Unsecured Debt.
	(d)	See Note 8, Noncontrolling Interests.
	There were no transfers into or out of each of the levels of the fair value hierarchy for the periods ending September 30, 2014 and December 31, 2013.
	Financial Instruments Carried at Fair Value
	The fair values of interest rate swaps are determined using the market standard methodology of netting the discounted future fixed cash receipts (or payments) and the discounted expected variable cash payments (or receipts). The variable cash payments (or receipts) are based on an expectation of future interest rates (forward curves) derived from observable market interest rate curves. The fair values of interest rate options are determined using the market standard methodology of discounting the future expected cash receipts that would occur if variable interest rates rise above the strike rate of the caps. The variable interest rates used in the calculation of projected receipts on the cap are based on an expectation of future interest rates derived from observable market interest rate curves and volatilities.
	The Company incorporates credit valuation adjustments to appropriately reflect both its own nonperformance risk and the respective counterparty’s nonperformance risk in the fair value measurements. In adjusting the fair value of its derivative contracts for the effect of nonperformance risk, the Company has considered the impact of netting and any applicable credit enhancements, such as collateral postings, thresholds, mutual puts, and guarantees.
	Although the Company has determined that the majority of the inputs used to value its derivatives fall within Level 2 of the fair value hierarchy, the credit valuation adjustments associated with its derivatives utilize Level 3 inputs, such as estimates of current credit spreads to evaluate the likelihood of default by itself and its counterparties. However, as of September 30, 2014 and December 31, 2013, the Company has assessed the significance of the impact of the credit valuation adjustments on the overall valuation of its derivative positions and has determined that the credit valuation adjustments are not significant to the overall valuation of its derivatives. As a result, the Company has determined that its derivative valuations in their entirety are classified in Level 2 of the fair value hierarchy. In conjunction with the FASB’s fair value measurement guidance, the Company made an accounting policy election to measure the credit risk of its derivative financial instruments that are subject to master netting agreements on a net basis by counterparty portfolio.
	Redeemable noncontrolling interests in the Operating Partnership have a redemption feature and are marked to their redemption value. The redemption value is based on the fair value of the Company’s common stock at the redemption date, and therefore, is calculated based on the fair value of the Company’s common stock at the balance sheet date. Since the valuation is based on observable inputs such as quoted prices for similar instruments in active markets, redeemable noncontrolling interests in the Operating Partnership are classified as Level 2.
	Financial Instruments Not Carried at Fair Value
At September 30, 2014, the fair values of cash and cash equivalents, restricted cash, accounts receivable, prepaids, real estate taxes payable, accrued interest payable, security deposits and prepaid rent, distributions payable and accounts payable approximated their carrying values because of the short term nature of these instruments. The estimated fair values of other financial instruments were determined by the Company using available market information and appropriate valuation methodologies. Considerable judgment is necessary to interpret market data and develop estimated fair values. Accordingly, the estimates presented herein are not necessarily indicative of the amounts the Company would realize on the disposition of the financial instruments. The use of different market assumptions or estimation methodologies may have a material effect on the estimated fair value amounts.
We estimate the fair value of our notes receivable and debt instruments by discounting the remaining cash flows of the debt instrument at a discount rate equal to the replacement market credit spread plus the corresponding treasury yields. Factors considered in determining a replacement market credit spread include general market conditions, borrower specific credit spreads, time remaining to maturity, loan-to-value ratios and collateral quality, where applicable (Level 3).
We record impairment losses on long-lived assets used in operations when events and circumstances indicate that the assets might be impaired and the undiscounted cash flows estimated to be generated by the future operation and disposition of those assets are less than the net book value of those assets. Our cash flow estimates are based upon historical results adjusted to reflect our best estimate of future market and operating conditions and our estimated holding periods. The net book value of impaired assets is reduced to fair value. Our estimates of fair value represent our best estimate based upon Level 3 inputs such as industry trends and reference to market rates and transactions.
We consider various factors to determine if a decrease in the value of our investment in and advances to unconsolidated joint ventures, net is other-than-temporary. These factors include, but are not limited to, age of the venture, our intent and ability to retain our investment in the entity, the financial condition and long-term prospects of the entity, and the relationships with the other joint venture partners and its lenders. Based on the significance of the unobservable inputs, we classify these fair value measurements within Level 3 of the valuation hierarchy. The Company did not incur any other-than-temporary decrease in the value of its investments in unconsolidated joint ventures during the three and nine months ended September 30, 2014 and 2013.
After determining an other-than-temporary decrease in the value of an equity method investment has occurred, we estimate the fair value of our investment by estimating the proceeds we would receive upon a hypothetical liquidation of the investment at the date of measurement. Inputs reflect management’s best estimate of what market participants would use in pricing the investment giving consideration to the terms of the joint venture agreement and the estimated discounted future cash flows to be generated from the underlying joint venture assets. The inputs and assumptions utilized to estimate the future cash flows of the underlying assets are based upon the Company’s evaluation of the economy, market trends, operating results, and other factors, including judgments regarding costs to complete any construction activities, lease up and occupancy rates, rental rates, inflation rates, capitalization rates utilized to estimate the projected cash flows at the disposition, and discount rates.
United Dominion Reality L.P. [Member]	'
Entity Information [Line Items]	'
FAIR VALUE OF DERIVATIVES AND FINANCIAL INSTRUMENTS	'
	FAIR VALUE OF DERIVATIVES AND FINANCIAL INSTRUMENTS
	Fair value is based on the price that would be received to sell an asset or the exit price that would be paid to transfer a liability in an orderly transaction between market participants at the measurement date. A three-level valuation hierarchy prioritizes observable and unobservable inputs used to measure fair value. The fair value hierarchy consists of three broad levels, which are described below:
	•	Level 1 — Quoted prices in active markets for identical assets or liabilities that the entity has the ability to access.
	•	Level 2 — Observable inputs other than prices included in Level 1, such as quoted prices for similar assets and liabilities in active markets; quoted prices for identical or similar assets and liabilities in markets that are not active; or other inputs that are observable or can be corroborated with observable market data.
	•	Level 3 — Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets and liabilities. This includes certain pricing models, discounted cash flow methodologies and similar techniques that use significant unobservable inputs.
	The estimated fair values of the Operating Partnership’s financial instruments either recorded or disclosed on a recurring basis as of September 30, 2014 and December 31, 2013 are summarized as follows (dollars in thousands):
						Fair Value at September 30, 2014, Using
		Total Carrying Amount in Statement of Financial Position on September 30, 2014		Fair Value Estimate at September 30, 2014		Quoted Prices in		Significant Other		Significant
						Active Markets		Observable		Unobservable
						for Identical		Inputs		Inputs
						Assets or		(Level 2)		(Level 3)
						Liabilities
						(Level 1)
	Description:
	Derivatives- Interest rate contracts (a)	$	5	$	5	$	—	$	5	$	—
	Total assets	$	5	$	5	$	—	$	5	$	—
	Derivatives- Interest rate contracts (a)	$	1,324	$	1,324	$	—	$	1,324	$	—
	Secured debt instruments- fixed rate: (b)
	Mortgage notes payable	380,506		392,883		—		—		392,883
	Fannie Mae credit facilities	378,709		394,849		—		—		394,849
	Secured debt instruments- variable rate: (b)
	Tax-exempt secured notes payable	27,000		27,000		—		—		27,000
	Fannie Mae credit facilities	142,059		142,059		—		—		142,059
	Total liabilities	$	929,598	$	958,115	$	—	$	1,324	$	956,791
						Fair Value at December 31, 2013, Using
		Total Carrying Amount in Statement of Financial Position on December 31, 2013		Fair Value Estimate at December 31, 2013		Quoted Prices in		Significant Other		Significant
						Active Markets		Observable		Unobservable
						for Identical		Inputs		Inputs
						Assets or		(Level 2)		(Level 3)
						Liabilities
						(Level 1)
	Description:
	Derivatives- Interest rate contracts (a)	$	2,731	$	2,731	$	—	$	2,731	$	—
	Secured debt instruments- fixed rate: (b)
	Mortgage notes payable	386,803		403,695		—		—		403,695
	Fannie Mae credit facilities	379,003		394,239		—		—		394,239
	Secured debt instruments- variable rate: (b)
	Tax-exempt secured notes payable	27,000		27,000		—		—		27,000
	Fannie Mae credit facilities	142,059		142,059		—		—		142,059
	Total liabilities	$	937,596	$	969,724	$	—	$	2,731	$	966,993
	(a)	See Note 8, Derivatives and Hedging Activity.
	(b)	See Note 5, Debt.
	Financial Instruments Carried at Fair Value
	The fair values of interest rate swaps are determined using the market standard methodology of netting the discounted future fixed cash receipts (or payments) and the discounted expected variable cash payments (or receipts). The variable cash payments (or receipts) are based on an expectation of future interest rates (forward curves) derived from observable market interest rate curves. The fair values of interest rate options are determined using the market standard methodology of discounting the future expected cash receipts that would occur if variable interest rates rise above the strike rate of the caps. The variable interest rates used in the calculation of projected receipts on the cap are based on an expectation of future interest rates derived from observable market interest rate curves and volatilities.
	The General Partner, on behalf of the Operating Partnership, incorporates credit valuation adjustments to appropriately reflect both its own nonperformance risk and the respective counterparty’s nonperformance risk in the fair value measurements. In adjusting the fair value of its derivative contracts for the effect of nonperformance risk, the Operating Partnership has considered the impact of netting and any applicable credit enhancements, such as collateral postings, thresholds, mutual puts, and guarantees.
	Although the General Partner, on behalf of the Operating Partnership, has determined that the majority of the inputs used to value its derivatives fall within Level 2 of the fair value hierarchy, the credit valuation adjustments associated with its derivatives utilize Level 3 inputs, such as estimates of current credit spreads to evaluate the likelihood of default by itself and its counterparties. However, as of September 30, 2014 and December 31, 2013, the Operating Partnership has assessed the significance of the impact of the credit valuation adjustments on the overall valuation of its derivative positions and has determined that the credit valuation adjustments are not significant to the overall valuation of its derivatives. As a result, the Operating Partnership has determined that its derivative valuations in their entirety are classified in Level 2 of the fair value hierarchy. In conjunction with the FASB’s fair value measurement guidance, the Operating Partnership made an accounting policy election to measure the credit risk of its derivative financial instruments that are subject to master netting agreements on a net basis by counterparty portfolio.
	Financial Instruments Not Carried at Fair Value
	As of September 30, 2014, the fair values of cash and cash equivalents, restricted cash, accounts receivable, prepaids, real estate taxes payable, accrued interest payable, security deposits and prepaid rent, distributions payable and accounts payable approximated their carrying values because of the short term nature of these instruments. The estimated fair values of other financial instruments were determined by the Operating Partnership using available market information and appropriate valuation methodologies. Considerable judgment is necessary to interpret market data and develop estimated fair values. Accordingly, the estimates presented herein are not necessarily indicative of the amounts the Operating Partnership would realize on the disposition of the financial instruments. The use of different market assumptions or estimation methodologies may have a material effect on the estimated fair value amounts.
	Fair value of our debt instruments is estimated by discounting the remaining cash flows of the debt instrument at a discount rate equal to the replacement market credit spread plus the corresponding treasury yields. Factors considered in determining a replacement market credit spread include general market conditions, borrower specific credit spreads, time remaining to maturity, loan-to-value ratios and collateral quality (Level 3).
	The Operating Partnership records impairment losses on long-lived assets used in operations when events and circumstances indicate that the assets might be impaired and the undiscounted cash flows estimated to be generated by the future operation and disposition of those assets are less than the net book value of those assets. Cash flow estimates are based upon historical results adjusted to reflect management’s best estimate of future market and operating conditions and our estimated holding periods. The net book value of impaired assets is reduced to fair value. The General Partner’s estimates of fair value represent management’s estimates based upon Level 3 inputs such as industry trends and reference to market rates and transactions.

Derivatives_and_Hedging_Activi

Derivatives and Hedging Activity	9 Months Ended
	Sep. 30, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]	'
Derivative Instruments and Hedging Activities Disclosure [Text Block]	'
	DERIVATIVES AND HEDGING ACTIVITY
	Risk Management Objective of Using Derivatives
	The Company is exposed to certain risks arising from both its business operations and economic conditions. The Company principally manages its exposures to a wide variety of business and operational risks through management of its core business activities. The Company manages economic risks, including interest rate, liquidity, and credit risk primarily by managing the amount, sources, and duration of its debt funding and through the use of derivative financial instruments. Specifically, the Company may enter into derivative financial instruments to manage exposures that arise from business activities that result in the receipt or payment of future known and uncertain cash amounts, the value of which are determined by interest rates. The Company’s derivative financial instruments are used to manage differences in the amount, timing, and duration of the Company’s known or expected cash receipts and its known or expected cash payments principally related to the Company’s investments and borrowings.
	Cash Flow Hedges of Interest Rate Risk
	The Company’s objectives in using interest rate derivatives are to add stability to interest expense and to manage its exposure to interest rate movements. To accomplish this objective, the Company primarily uses interest rate swaps and caps as part of its interest rate risk management strategy. Interest rate swaps designated as cash flow hedges involve the receipt of variable-rate amounts from a counterparty in exchange for the Company making fixed-rate payments over the life of the agreements without exchange of the underlying notional amount. Interest rate caps designated as cash flow hedges involve the receipt of variable-rate amounts from a counterparty if interest rates rise above the strike rate on the contract in exchange for an up front premium.
	The effective portion of changes in the fair value of derivatives designated and that qualify as cash flow hedges is recorded in Accumulated other comprehensive income/(loss), net in the Consolidated Balance Sheets and is subsequently reclassified into earnings in the period that the hedged forecasted transaction affects earnings. During the three and nine months ended September 30, 2014 and 2013, such derivatives were used to hedge the variable cash flows associated with existing variable-rate debt. The ineffective portion of the change in fair value of the derivatives is recognized directly in earnings. During the three and nine months ended September 30, 2014, the Company recorded no gain or loss and a gain of approximately $3,000, respectively, related to the ineffective portion of the derivative, which was caused by a timing difference between the derivative and the hedged item. During the three and nine months ended September 30, 2013, the Company recorded a loss of less than $1,000 related to the ineffective portion of the derivative, which was caused by an index difference between the derivative and the hedged item.
	Amounts reported in Accumulated other comprehensive income/(loss), net in the Consolidated Balance Sheets related to derivatives will be reclassified to interest expense as interest payments are made on the Company’s variable-rate debt. Through September 30, 2015, the Company estimates that an additional $4.4 million will be reclassified as an increase to interest expense.
	As of September 30, 2014, the Company had the following outstanding interest rate derivatives that were designated as cash flow hedges of interest rate risk (dollars in thousands):
	Interest Rate Derivative		Number of Instruments		Notional
	Interest rate swaps		14		$	419,787
	Interest rate caps		6		$	339,488
	Derivatives not designated as hedges are not speculative and are used to manage the Company’s exposure to interest rate movements and other identified risks but do not meet the strict hedge accounting requirements of GAAP. Changes in the fair value of derivatives not designated in hedging relationships are recorded directly in earnings and resulted in no adjustment to earnings for the three and nine months ended September 30, 2014 and a gain/(loss) of $280,000 and $275,000 for the three and nine months ended September 30, 2013, respectively.
	As of September 30, 2014, the Company did not have any outstanding derivatives that were not designated as hedges in qualifying hedging relationships.
	Tabular Disclosure of Fair Values of Derivative Instruments on the Balance Sheet
	The tables below present the fair value of the Company’s derivative financial instruments as well as their classification on the Consolidated Balance Sheets as of September 30, 2014 and December 31, 2013 (dollars in thousands):
		Asset Derivatives										Liability Derivatives
				Fair Value at:										Fair Value at:
		Balance		September 30,				December 31,				Balance		September 30,				December 31,
		Sheet Location		2014				2013				Sheet Location		2014				2013
	Derivatives designated as hedging instruments:
	Interest rate products	Other assets		$	299			—				Other liabilities		$	2,382			4,965
	Derivatives not designated as hedging instruments:
	Interest rate products	Other assets		$	—			$	—			Other liabilities		$	—			$	—
	Tabular Disclosure of the Effect of Derivative Instruments on the Consolidated Statements of Operations
	The tables below present the effect of the Company’s derivative financial instruments on the Consolidated Statements of Operations for the three and nine months ended September 30, 2014 and 2013 (dollars in thousands):
			Amount of Gain or (Loss) Recognized in OCI on Derivative (Effective Portion)								Location of Gain or (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)		Amount of Gain or (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)								Location of Gain or (Loss) Recognized in Income on Derivative (Ineffective Portion and Amount Excluded from Effectiveness Testing)	Amount of Gain or (Loss) Recognized in Income on Derivative (Ineffective Portion and Amount Excluded from Effectiveness Testing)
	Derivatives in Cash Flow Hedging Relationships		2014				2013						2014				2013					2014		2013
	For the Three Months Ended September 30,
	Interest rate products		$	362			$	(386	)		Interest expense		$	(1,130	)		$	(1,635	)		Interest expense	$	—	$	—
	For the Nine Months Ended September 30,
	Interest rate products		$	611			$	(334	)		Interest expense		$	(3,809	)		$	(5,180	)		Interest expense	$	3	$	—
	Derivatives Not Designated as Hedging Instruments		Location of Gain or (Loss) Recognized in Income on Derivative		Amount of Gain or (Loss) Recognized in Income on Derivative
					2014				2013
	For the Three Months Ended September 30,
	Interest rate products		Interest and other income/(loss), net		$	—			$	280
	For the Nine Months Ended September 30,
	Interest rate products		Interest and other income/(loss), net		$	—			$	275
	Credit-risk-related Contingent Features
	The Company has agreements with some of its derivative counterparties that contain a provision where (1) if the Company defaults on any of its indebtedness, including default where repayment of the indebtedness has not been accelerated by the lender, then the Company could also be declared in default on its derivative obligations; or (2) the Company could be declared in default on its derivative obligations if repayment of the underlying indebtedness is accelerated by the lender due to the Company’s default on the indebtedness.
	Certain of the Company’s agreements with its derivative counterparties contain provisions where, if there is a change in the Company’s financial condition that materially changes the Company’s creditworthiness in an adverse manner, the Company may be required to fully collateralize its obligations under the derivative instrument.
	The Company also has an agreement with a derivative counterparty that incorporates the loan and financial covenant provisions of the Company’s indebtedness with a lender affiliate of the derivative counterparty. Failure to comply with these covenant provisions would result in the Company being in default on any derivative instrument obligations covered by the agreement.
	As of September 30, 2014, the fair value of derivatives in a net liability position, which includes accrued interest but excludes any adjustment for nonperformance risk, related to these agreements was $2.4 million. As of September 30, 2014, the Company has not posted any collateral related to these agreements. If the Company had breached any of these provisions at September 30, 2014, it may have been required to settle its obligations under the agreements at their termination value of $2.4 million.
	Tabular Disclosure of Offsetting Derivatives
	Company has elected not to offset derivative positions in the consolidated financial statements. The tables below present the effect on its financial position had the Company made the election to offset its derivative positions as of September 30, 2014 and December 31, 2013 (dollar in thousands):
	Offsetting of Derivative Assets
															Gross Amounts Not Offset in the Consolidated Balance Sheets
			Gross Amounts of Recognized Assets				Gross Amounts Offset in the Consolidated Balance Sheets				Net Amounts of Assets Presented in the Consolidated Balance Sheets (a)				Financial Instruments				Cash Collateral Received			Net Amount
	September 30, 2014		$	299			$	—			$	299			$	(253	)		$	—		$	46
	December 31, 2013		$	—			$	—			$	—			$	—			$	—		$	—
	(a) 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.
	Offsetting of Derivative Liabilities
															Gross Amounts Not Offset in the Consolidated Balance Sheets
			Gross Amounts of Recognized Liabilities				Gross Amounts Offset in the Consolidated Balance Sheets				Net Amounts of Liabilities Presented in the Consolidated Balance Sheets (b)				Financial Instruments				Cash Collateral Posted			Net Amount
	September 30, 2014		$	2,382			$	—			$	2,382			$	(253	)		$	—		$	2,129
	December 31, 2013		$	4,965			$	—			$	4,965			$	—			$	—		$	4,965
	(b) 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.

Derivatives_and_Hedging_Activi1

Derivatives and Hedging Activity (UNITED DOMINION REALTY, L.P.)	9 Months Ended
	Sep. 30, 2014
Entity Information [Line Items]	'
DERIVATIVES AND HEDGING ACTIVITY	'
	DERIVATIVES AND HEDGING ACTIVITY
	Risk Management Objective of Using Derivatives
	The Company is exposed to certain risks arising from both its business operations and economic conditions. The Company principally manages its exposures to a wide variety of business and operational risks through management of its core business activities. The Company manages economic risks, including interest rate, liquidity, and credit risk primarily by managing the amount, sources, and duration of its debt funding and through the use of derivative financial instruments. Specifically, the Company may enter into derivative financial instruments to manage exposures that arise from business activities that result in the receipt or payment of future known and uncertain cash amounts, the value of which are determined by interest rates. The Company’s derivative financial instruments are used to manage differences in the amount, timing, and duration of the Company’s known or expected cash receipts and its known or expected cash payments principally related to the Company’s investments and borrowings.
	Cash Flow Hedges of Interest Rate Risk
	The Company’s objectives in using interest rate derivatives are to add stability to interest expense and to manage its exposure to interest rate movements. To accomplish this objective, the Company primarily uses interest rate swaps and caps as part of its interest rate risk management strategy. Interest rate swaps designated as cash flow hedges involve the receipt of variable-rate amounts from a counterparty in exchange for the Company making fixed-rate payments over the life of the agreements without exchange of the underlying notional amount. Interest rate caps designated as cash flow hedges involve the receipt of variable-rate amounts from a counterparty if interest rates rise above the strike rate on the contract in exchange for an up front premium.
	The effective portion of changes in the fair value of derivatives designated and that qualify as cash flow hedges is recorded in Accumulated other comprehensive income/(loss), net in the Consolidated Balance Sheets and is subsequently reclassified into earnings in the period that the hedged forecasted transaction affects earnings. During the three and nine months ended September 30, 2014 and 2013, such derivatives were used to hedge the variable cash flows associated with existing variable-rate debt. The ineffective portion of the change in fair value of the derivatives is recognized directly in earnings. During the three and nine months ended September 30, 2014, the Company recorded no gain or loss and a gain of approximately $3,000, respectively, related to the ineffective portion of the derivative, which was caused by a timing difference between the derivative and the hedged item. During the three and nine months ended September 30, 2013, the Company recorded a loss of less than $1,000 related to the ineffective portion of the derivative, which was caused by an index difference between the derivative and the hedged item.
	Amounts reported in Accumulated other comprehensive income/(loss), net in the Consolidated Balance Sheets related to derivatives will be reclassified to interest expense as interest payments are made on the Company’s variable-rate debt. Through September 30, 2015, the Company estimates that an additional $4.4 million will be reclassified as an increase to interest expense.
	As of September 30, 2014, the Company had the following outstanding interest rate derivatives that were designated as cash flow hedges of interest rate risk (dollars in thousands):
	Interest Rate Derivative		Number of Instruments		Notional
	Interest rate swaps		14		$	419,787
	Interest rate caps		6		$	339,488
	Derivatives not designated as hedges are not speculative and are used to manage the Company’s exposure to interest rate movements and other identified risks but do not meet the strict hedge accounting requirements of GAAP. Changes in the fair value of derivatives not designated in hedging relationships are recorded directly in earnings and resulted in no adjustment to earnings for the three and nine months ended September 30, 2014 and a gain/(loss) of $280,000 and $275,000 for the three and nine months ended September 30, 2013, respectively.
	As of September 30, 2014, the Company did not have any outstanding derivatives that were not designated as hedges in qualifying hedging relationships.
	Tabular Disclosure of Fair Values of Derivative Instruments on the Balance Sheet
	The tables below present the fair value of the Company’s derivative financial instruments as well as their classification on the Consolidated Balance Sheets as of September 30, 2014 and December 31, 2013 (dollars in thousands):
		Asset Derivatives										Liability Derivatives
				Fair Value at:										Fair Value at:
		Balance		September 30,				December 31,				Balance		September 30,				December 31,
		Sheet Location		2014				2013				Sheet Location		2014				2013
	Derivatives designated as hedging instruments:
	Interest rate products	Other assets		$	299			—				Other liabilities		$	2,382			4,965
	Derivatives not designated as hedging instruments:
	Interest rate products	Other assets		$	—			$	—			Other liabilities		$	—			$	—
	Tabular Disclosure of the Effect of Derivative Instruments on the Consolidated Statements of Operations
	The tables below present the effect of the Company’s derivative financial instruments on the Consolidated Statements of Operations for the three and nine months ended September 30, 2014 and 2013 (dollars in thousands):
			Amount of Gain or (Loss) Recognized in OCI on Derivative (Effective Portion)								Location of Gain or (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)		Amount of Gain or (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)								Location of Gain or (Loss) Recognized in Income on Derivative (Ineffective Portion and Amount Excluded from Effectiveness Testing)	Amount of Gain or (Loss) Recognized in Income on Derivative (Ineffective Portion and Amount Excluded from Effectiveness Testing)
	Derivatives in Cash Flow Hedging Relationships		2014				2013						2014				2013					2014		2013
	For the Three Months Ended September 30,
	Interest rate products		$	362			$	(386	)		Interest expense		$	(1,130	)		$	(1,635	)		Interest expense	$	—	$	—
	For the Nine Months Ended September 30,
	Interest rate products		$	611			$	(334	)		Interest expense		$	(3,809	)		$	(5,180	)		Interest expense	$	3	$	—
	Derivatives Not Designated as Hedging Instruments		Location of Gain or (Loss) Recognized in Income on Derivative		Amount of Gain or (Loss) Recognized in Income on Derivative
					2014				2013
	For the Three Months Ended September 30,
	Interest rate products		Interest and other income/(loss), net		$	—			$	280
	For the Nine Months Ended September 30,
	Interest rate products		Interest and other income/(loss), net		$	—			$	275
	Credit-risk-related Contingent Features
	The Company has agreements with some of its derivative counterparties that contain a provision where (1) if the Company defaults on any of its indebtedness, including default where repayment of the indebtedness has not been accelerated by the lender, then the Company could also be declared in default on its derivative obligations; or (2) the Company could be declared in default on its derivative obligations if repayment of the underlying indebtedness is accelerated by the lender due to the Company’s default on the indebtedness.
	Certain of the Company’s agreements with its derivative counterparties contain provisions where, if there is a change in the Company’s financial condition that materially changes the Company’s creditworthiness in an adverse manner, the Company may be required to fully collateralize its obligations under the derivative instrument.
	The Company also has an agreement with a derivative counterparty that incorporates the loan and financial covenant provisions of the Company’s indebtedness with a lender affiliate of the derivative counterparty. Failure to comply with these covenant provisions would result in the Company being in default on any derivative instrument obligations covered by the agreement.
	As of September 30, 2014, the fair value of derivatives in a net liability position, which includes accrued interest but excludes any adjustment for nonperformance risk, related to these agreements was $2.4 million. As of September 30, 2014, the Company has not posted any collateral related to these agreements. If the Company had breached any of these provisions at September 30, 2014, it may have been required to settle its obligations under the agreements at their termination value of $2.4 million.
	Tabular Disclosure of Offsetting Derivatives
	Company has elected not to offset derivative positions in the consolidated financial statements. The tables below present the effect on its financial position had the Company made the election to offset its derivative positions as of September 30, 2014 and December 31, 2013 (dollar in thousands):
	Offsetting of Derivative Assets
															Gross Amounts Not Offset in the Consolidated Balance Sheets
			Gross Amounts of Recognized Assets				Gross Amounts Offset in the Consolidated Balance Sheets				Net Amounts of Assets Presented in the Consolidated Balance Sheets (a)				Financial Instruments				Cash Collateral Received			Net Amount
	September 30, 2014		$	299			$	—			$	299			$	(253	)		$	—		$	46
	December 31, 2013		$	—			$	—			$	—			$	—			$	—		$	—
	(a) 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.
	Offsetting of Derivative Liabilities
															Gross Amounts Not Offset in the Consolidated Balance Sheets
			Gross Amounts of Recognized Liabilities				Gross Amounts Offset in the Consolidated Balance Sheets				Net Amounts of Liabilities Presented in the Consolidated Balance Sheets (b)				Financial Instruments				Cash Collateral Posted			Net Amount
	September 30, 2014		$	2,382			$	—			$	2,382			$	(253	)		$	—		$	2,129
	December 31, 2013		$	4,965			$	—			$	4,965			$	—			$	—		$	4,965
	(b) 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.
United Dominion Reality L.P. [Member]	'
Entity Information [Line Items]	'
DERIVATIVES AND HEDGING ACTIVITY	'
	DERIVATIVES AND HEDGING ACTIVITY
	Risk Management Objective of Using Derivatives
	The Operating Partnership is exposed to certain risks arising from both its business operations and economic conditions. The General Partner principally manages its exposures to a wide variety of business and operational risks through management of its core business activities. The General Partner manages economic risks, including interest rate, liquidity, and credit risk primarily by managing the amount, sources, and duration of its debt funding and through the use of derivative financial instruments. Specifically, the General Partner enters into derivative financial instruments to manage exposures that arise from business activities that result in the receipt or payment of future known and uncertain cash amounts, the value of which are determined by interest rates. The General Partner’s and the Operating Partnership’s derivative financial instruments are used to manage differences in the amount, timing, and duration of the General Partner’s known or expected cash payments principally related to the General Partner’s borrowings.
	Cash Flow Hedges of Interest Rate Risk
	The General Partner’s objectives in using interest rate derivatives are to add stability to interest expense and to manage its exposure to interest rate movements. To accomplish this objective, the General Partner primarily uses interest rate swaps and caps as part of its interest rate risk management strategy. Interest rate swaps designated as cash flow hedges involve the receipt of variable-rate amounts from a counterparty in exchange for the General Partner making fixed-rate payments over the life of the agreements without exchange of the underlying notional amount. Interest rate caps designated as cash flow hedges involve the receipt of variable-rate amounts from a counterparty if interest rates rise above the strike rate on the contract in exchange for an up front premium.
	A portion of the General Partner’s interest rate derivatives have been allocated to the Operating Partnership based on the General Partner’s underlying debt instruments allocated to the Operating Partnership. (See Note 5, Debt.)
	The effective portion of changes in the fair value of derivatives designated and that qualify as cash flow hedges is recorded in Accumulated other comprehensive income/(loss), net in the Consolidated Balance Sheets and is subsequently reclassified into earnings in the period that the hedged forecasted transaction affects earnings. During the three and nine months ended September 30, 2014 and 2013, such derivatives were used to hedge the variable cash flows associated with existing variable-rate debt. The ineffective portion of the change in fair value of the derivatives is recognized directly in earnings. The Operating Partnership recorded zero gain or loss from ineffectiveness during the three and nine months ended September 30, 2014, and less than $1,000 of loss from ineffectiveness during the three and nine months ended September 30, 2013.
	Amounts reported in Accumulated other comprehensive income/(loss), net related to derivatives will be reclassified to interest expense as interest payments are made on the General Partner’s variable-rate debt that is allocated to the Operating Partnership. During the next twelve months through September 30, 2015, we estimate that an additional $1.3 million will be reclassified as an increase to interest expense.
	As of September 30, 2014, the Operating Partnership had the following outstanding interest rate derivatives designated as cash flow hedges of interest rate risk (dollars in thousands):
	Interest Rate Derivative		Number of Instruments		Notional
	Interest rate swaps		2		$	96,974
	Interest rate caps		5		$	255,561
	Derivatives not designated as hedges are not speculative and are used to manage the Company’s exposure to interest rate movements and other identified risks but do not meet the strict hedge accounting requirements of GAAP. Changes in the fair value of derivatives not designated in hedging relationships are recorded directly in earnings and resulted in no adjustment to earnings for the three and nine months ended September 30, 2014 and gains/(losses) of zero and $(5,000) for the three and nine months ended September 30, 2013, respectively.
	As of September 30, 2014, the Operating Partnership did not have any outstanding derivatives that were not designated as hedges in qualifying hedging relationships.
	Tabular Disclosure of Fair Values of Derivative Instruments on the Balance Sheet
	The table below presents the fair value of the Operating Partnership’s derivative financial instruments as well as their classification on the Consolidated Balance Sheets as of September 30, 2014 and December 31, 2013 (dollars in thousands):
		Asset Derivatives										Liability Derivatives
				Fair Value at:										Fair Value at:
		Balance		September 30,				December 31,				Balance		September 30,				December 31,
		Sheet Location		2014				2013				Sheet Location		2014				2013
	Derivatives designated as hedging instruments:
	Interest rate products	Other assets		$	5			$	—			Other liabilities		$	1,324			$	2,731
	Derivatives not designated as hedging instruments:
	Interest rate products	Other assets		$	—			$	—			Other liabilities		$	—			$	—
	Tabular Disclosure of the Effect of Derivative Instruments on the Consolidated Statements of Operations
	The tables below present the effect of the derivative financial instruments on the Consolidated Statements of Operations for the three and nine months ended September 30, 2014 and 2013 (dollars in thousands):
			Amount of Gain or (Loss) Recognized in OCI on Derivatives (Effective Portion)								Location of Gain or (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)
	Derivatives in Cash Flow Hedging Relationships												Amount of Gain or (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)
			2014				2013						2014				2013
	For the Three Months Ended September 30,
	Interest rate products		$	(3	)		$	(201	)		Interest expense		$	(588	)		$	(590	)
	For the Nine Months Ended September 30,
	Interest rate products		$	(194	)		$	(284	)		Interest expense		$	(1,784	)		$	(2,041	)
		Derivatives Not Designated as Hedging Instruments		Location of Gain or (Loss) Recognized in Income on Derivatives		Amount of Gain or (Loss) Recognized in Income on Derivatives
						2014				2013
		For the Three Months Ended September 30,
		Interest rate products		Other operating expenses		$	—			$	—
		For the Nine Months Ended September 30,
		Interest rate products		Other operating expenses		$	—			$	(5	)
	Credit-risk-related Contingent Features
	The General Partner has agreements with some of its derivative counterparties that contain a provision where (1) if the General Partner defaults on any of its indebtedness, including default where repayment of the indebtedness has not been accelerated by the lender, then the General Partner could also be declared in default on its derivative obligations; or (2) the General Partner could be declared in default on its derivative obligations if repayment of the underlying indebtedness is accelerated by the lender due to the General Partner’s default on the indebtedness.
	Certain of the General Partner’s agreements with its derivative counterparties contain provisions where if there is a change in the General Partner’s financial condition that materially changes the General Partner’s creditworthiness in an adverse manner, the General Partner may be required to fully collateralize its obligations under the derivative instrument. At September 30, 2014 and December 31, 2013, no cash collateral was posted or required to be posted by the General Partner or by a counterparty.
	The General Partner also has an agreement with a derivative counterparty that incorporates the loan and financial covenant provisions of the General Partner’s indebtedness with a lender affiliate of the derivative counterparty. Failure to comply with these covenant provisions would result in the General Partner being in default on any derivative instrument obligations covered by the agreement.
	The General Partner has certain agreements with some of its derivative counterparties that contain a provision where in the event of default by the General Partner or the counterparty, the right of setoff may be exercised. Any amount payable to one party by the other party may be reduced by its setoff against any amounts payable by the other party. Events that give rise to default by either party may include, but are not limited to, the failure to pay or deliver payment under the derivative contract, the failure to comply with or perform under the derivative agreement, bankruptcy, a merger without assumption of the derivative agreement, or in a merger, a surviving entity’s creditworthiness is materially weaker than the original party to the derivative agreement.
	As of September 30, 2014, the fair value of derivatives in a net liability position that were allocated to the Operating Partnership, which includes accrued interest but excludes any adjustment for nonperformance risk, related to these agreements was $1.5 million. As of September 30, 2014, the General Partner has not posted any collateral related to these agreements. If the General Partner had breached any of these provisions at September 30, 2014, it would have been required to settle its obligations under the agreements at their termination value of $1.5 million.
	The General Partner has elected not to offset derivative positions in the consolidated financial statements. The table below presents the effect on the Operating Partnership’s financial position had the General Partner made the election to offset its derivative positions as of September 30, 2014 and December 31, 2013:
	Offsetting of Derivative Assets
															Gross Amounts Not Offset in the Consolidated Balance Sheets
			Gross Amounts of Recognized Assets				Gross Amounts Offset in the Consolidated Balance Sheets				Net Amounts of Assets Presented in the Consolidated Balance Sheets (a)				Financial Instruments				Cash Collateral Received			Net Amount
	September 30, 2014		$	5			$	—			$	5			$	—			$	—		$	5
	December 31, 2013		$	—			$	—			$	—			$	—			$	—		$	—
	(a) 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.
	Offsetting of Derivative Liabilities
															Gross Amounts Not Offset in the Consolidated Balance Sheets
			Gross Amounts of Recognized Liabilities				Gross Amounts Offset in the Consolidated Balance Sheets				Net Amounts of Liabilities Presented in the Consolidated Balance Sheets (b)				Financial Instruments				Cash Collateral Posted			Net Amount
	September 30, 2014		$	1,324			$	—			$	1,324			$	—			$	—		$	1,324
	December 31, 2013		$	2,731			$	—			$	2,731			$	—			$	—		$	2,731
	(b) 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.

Stock_Based_Compensation

Stock Based Compensation	9 Months Ended
	Sep. 30, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]	'
STOCK BASED COMPENSATION	'
	STOCK BASED COMPENSATION
	The Company recognized stock based compensation expense, inclusive of awards granted to our independent directors, of $3.5 million and $10.8 million during the three and nine months ended September 30, 2014, respectively, and $2.4 million and $6.7 million during the three and nine months ended September 30, 2013, respectively.

Capital_Structure_UNITED_DOMIN

Capital Structure (UNITED DOMINION REALTY, L.P.) (United Dominion Reality L.P. [Member])	9 Months Ended
	Sep. 30, 2014
United Dominion Reality L.P. [Member]	'
Entity Information [Line Items]	'
CAPITAL STRUCTURE	'
	CAPITAL STRUCTURE
	General Partnership Units
	The General Partner has complete discretion to manage and control the operations and business of the Operating Partnership, which includes but is not limited to the acquisition and disposition of real property, construction of buildings and making capital improvements, and the borrowing of funds from outside lenders or UDR and its subsidiaries to finance such activities. The General Partner can generally authorize, issue, sell, redeem or purchase any OP Unit or securities of the Operating Partnership without the approval of the limited partners. The General Partner can also approve, with regard to the issuances of OP Units, the class or one or more series of classes, with designations, preferences, participating, optional or other special rights, powers and duties including rights, powers and duties senior to limited partnership interests without approval of any limited partners except holders of Class A Limited Partnership Units. There were 110,883 General Partnership units outstanding at September 30, 2014 and December 31, 2013, all of which were held by UDR.
	Limited Partnership Units
	As of September 30, 2014 and December 31, 2013, there were 183,167,815 limited partnership units outstanding, of which 1,873,332 were Class A Limited Partnership Units. UDR owned 174,000,344, or 95.0% of, and 173,848,891, or 94.9% of, OP Units outstanding at September 30, 2014 and December 31, 2013, respectively, of which 121,661 were Class A Limited Partnership Units. The remaining 9,167,471, or 5.0% of, and 9,318,924, or 5.1% of, OP Units outstanding, were held by non-affiliated partners at September 30, 2014 and December 31, 2013, respectively, of which 1,751,671 were Class A Limited Partnership Units.
	Subject to the terms of the Operating Partnership Agreement, the limited partners have the right to require the Operating Partnership to redeem all or a portion of the OP Units held by the limited partner at a redemption price equal to and in the form of the Cash Amount (as defined in the Operating Partnership Agreement), provided that such OP Units have been outstanding for at least one year. UDR, as general partner of the Operating Partnership may, in its sole discretion, purchase the OP Units by paying to the limited partner either the Cash Amount or the REIT Share Amount (generally one share of common stock of UDR for each OP Unit), as defined in the Operating Partnership Agreement.
	The non-affiliated limited partners’ capital is adjusted to redemption value at the end of each reporting period with the corresponding offset against UDR’s limited partner capital account based on the redemption rights noted above. The aggregate value upon redemption of the then-outstanding OP Units held by limited partners was $249.8 million and $217.6 million as of September 30, 2014 and December 31, 2013, respectively, based on the value of UDR’s common stock at each period end. A limited partner has no right to receive any distributions from the Operating Partnership on or after the date of redemption of its OP Units.
	Class A Limited Partnership Units
	Class A Limited Partnership Units have a cumulative, annual, non-compounded preferred return, which is equal to 8% based on a value of $16.61 per Class A Limited Partnership Unit.
	Holders of the Class A Limited Partnership Units exclusively possess certain voting rights. The Operating Partnership may not do the following without approval of the holders of the Class A Limited Partnership Units: (i) increase the authorized or issued amount of Class A Limited Partnership Units, (ii) reclassify any other partnership interest into Class A Limited Partnership Units, (iii) create, authorize or issue any obligations or security convertible into or the right to purchase any Class A Limited Partnership units, (iv) enter into a merger or acquisition, or (v) amend or modify the Agreement of Limited Partnership of the Operating Partnership in a manner that adversely affects the relative rights, preferences or privileges of the Class A Limited Partnership Units.
	Allocation of Profits and Losses
	Profit of the Operating Partnership is allocated in the following order: (i) to the General Partner and the Limited Partners in proportion to and up to the amount of cash distributions made during the year, and (ii) to the General Partner and Limited Partners in accordance with their percentage interests. Losses and depreciation and amortization expenses, non-recourse liabilities are allocated to the General Partner and Limited Partners in accordance with their percentage interests. Losses allocated to the Limited Partners are capped to the extent that such an allocation would not cause a deficit in the Limited Partners’ capital account. Such losses are, therefore, allocated to the General Partner. If any Partner’s capital balance were to fall into a deficit, any income and gains are allocated to each Partner sufficient to eliminate its negative capital balance.

Commitments_and_Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2014
Commitments and Contingencies Disclosure [Abstract]	'
COMMITMENTS AND CONTINGENCIES	'
	COMMITMENTS AND CONTINGENCIES
	Commitments
	Real Estate Under Development
	The following summarizes the Company’s real estate commitments at September 30, 2014 (dollars in thousands):
		Number of	Costs Incurred			Expected Costs			Average Ownership
		Properties	to Date (a)			to Complete			Stake
	Wholly-owned — under development	3	$	321,607	(b)	$	78,793		100	%
	Wholly-owned — redevelopment	1	80,619		(b)	17,381			100	%
	Joint ventures:
	Unconsolidated joint ventures	2	158,986			143,981		(c)	51	%
	Participating loan investments	1	43,822		(d)	48,187		(e)	0	%
			$	605,034		$	288,342
	(a)	Represents 100% of project costs incurred to date.
	(b)	Costs incurred to date include $26.8 million and $2.1 million of accrued fixed assets for development and redevelopment, respectively.
	(c)	Represents UDR’s contributed and remaining equity commitment in unconsolidated joint ventures.
	(d)	Represents the participating loan balance funded as of September 30, 2014.
	(e)	Represents UDR’s remaining participating loan commitment for Steele Creek.
	Contingencies
	Litigation and Legal Matters
	The Company is subject to various legal proceedings and claims arising in the ordinary course of business. The Company cannot determine the ultimate liability with respect to such legal proceedings and claims at this time. The Company believes that such liability, to the extent not provided for through insurance or otherwise, will not have a material adverse effect on our financial condition, results of operations or cash flow.

Commitments_and_Contingencies_

Commitments and Contingencies (UNITED DOMINION REALTY, L.P.) Commitments and Contingencies (UNITED DOMINION REALTY, L.P.)	9 Months Ended
	Sep. 30, 2014
Entity Information [Line Items]	'
COMMITMENTS AND CONTINGENCIES	'
	COMMITMENTS AND CONTINGENCIES
	Commitments
	Real Estate Under Development
	The following summarizes the Company’s real estate commitments at September 30, 2014 (dollars in thousands):
		Number of	Costs Incurred			Expected Costs			Average Ownership
		Properties	to Date (a)			to Complete			Stake
	Wholly-owned — under development	3	$	321,607	(b)	$	78,793		100	%
	Wholly-owned — redevelopment	1	80,619		(b)	17,381			100	%
	Joint ventures:
	Unconsolidated joint ventures	2	158,986			143,981		(c)	51	%
	Participating loan investments	1	43,822		(d)	48,187		(e)	0	%
			$	605,034		$	288,342
	(a)	Represents 100% of project costs incurred to date.
	(b)	Costs incurred to date include $26.8 million and $2.1 million of accrued fixed assets for development and redevelopment, respectively.
	(c)	Represents UDR’s contributed and remaining equity commitment in unconsolidated joint ventures.
	(d)	Represents the participating loan balance funded as of September 30, 2014.
	(e)	Represents UDR’s remaining participating loan commitment for Steele Creek.
	Contingencies
	Litigation and Legal Matters
	The Company is subject to various legal proceedings and claims arising in the ordinary course of business. The Company cannot determine the ultimate liability with respect to such legal proceedings and claims at this time. The Company believes that such liability, to the extent not provided for through insurance or otherwise, will not have a material adverse effect on our financial condition, results of operations or cash flow.
United Dominion Reality L.P. [Member]	'
Entity Information [Line Items]	'
COMMITMENTS AND CONTINGENCIES	'
	COMMITMENTS AND CONTINGENCIES
	Commitments
	Real Estate Under Development
	The following summarizes the Operating Partnership’s real estate commitments at September 30, 2014 (dollars in thousands):
		Number of	Costs Incurred			Expected Costs
		Properties	to Date (a)			to Complete (unaudited)
	Real estate communities — under development	1	$	119,828		$	12,172
	(a) Includes $7.0 million of accrued fixed assets for development.
	Contingencies
	Litigation and Legal Matters
	The Operating Partnership is subject to various legal proceedings and claims arising in the ordinary course of business. The Operating Partnership cannot determine the ultimate liability with respect to such legal proceedings and claims at this time. The General Partner believes that such liability, to the extent not provided for through insurance or otherwise, will not have a material adverse effect on the Operating Partnership’s financial condition, results of operations or cash flow.

Reportable_Segments

Reportable Segments	9 Months Ended
	Sep. 30, 2014
Segment Reporting [Abstract]	'
REPORTABLE SEGMENTS	'
	REPORTABLE SEGMENTS
	GAAP guidance requires that segment disclosures present the measure(s) used by the chief operating decision maker to decide how to allocate resources and for purposes of assessing such segments’ performance. UDR’s chief operating decision maker is comprised of several members of its executive management team who use several generally accepted industry financial measures to assess the performance of the business for our reportable operating segments.
	UDR owns and operates multifamily apartment communities that generate rental and other property related income through the leasing of apartment homes to a diverse base of tenants. The primary financial measures for UDR’s apartment communities are rental income and net operating income (“NOI”). Rental income represents gross market rent less adjustments for concessions, vacancy loss and bad debt. NOI is defined as rental income less direct property rental expenses. Rental expenses include real estate taxes, insurance, personnel, utilities, repairs and maintenance, administrative and marketing. Excluded from NOI is property management expense, which is calculated as 2.75% of property revenue to cover the regional supervision and accounting costs related to consolidated property operations, and land rent. UDR’s chief operating decision maker utilizes NOI as the key measure of segment profit or loss.
	UDR’s two reportable segments are Same-Store Communities and Non-Mature Communities/Other:
	•	Same-Store Communities represent those communities acquired, developed, and stabilized prior to July 1, 2013 for quarter-to-date comparison and January 1, 2013 for year-to-date comparison and held as of September 30, 2014. A comparison of operating results from the prior year is meaningful as these communities were owned and had stabilized occupancy and operating expenses as of the beginning of the prior period, there is no plan to conduct substantial redevelopment activities, and the community is not held for disposition within the current year. A community is considered to have stabilized occupancy once it achieves 90% occupancy for at least three consecutive months.
	•	Non-Mature Communities/Other represent those communities that do not meet the criteria to be included in Same-Store Communities, including, but not limited to, recently acquired, developed and redeveloped properties, and the non-apartment components of mixed use properties.
	Management evaluates the performance of each of our apartment communities on a Same-Store Community and Non-Mature Community/Other basis, as well as individually and geographically. This is consistent with the aggregation criteria under GAAP as each of our apartment communities generally has similar economic characteristics, facilities, services, and tenants. Therefore, the Company’s reportable segments have been aggregated by geography in a manner identical to that which is provided to the chief operating decision maker.
	All revenues are from external customers and no single tenant or related group of tenants contributed 10% or more of UDR’s total revenues during the three and nine months ended September 30, 2014 and 2013.
	The following table details rental income and NOI from continuing and discontinued operations for UDR’s reportable segments for the three and nine months ended September 30, 2014 and 2013, and reconciles NOI to Net Income/(Loss) Attributable to UDR, Inc. in the Consolidated Statements of Operations (dollars in thousands):
		Three Months Ended September 30, (a)						Nine Months Ended September 30, (b)
		2014			2013			2014			2013
	Reportable apartment home segment rental income
	Same-Store Communities
	West Region	$	68,275		$	64,195		$	189,075		$	177,884
	Mid-Atlantic Region	40,479			40,164			121,356			119,937
	Southeast Region	27,210			25,851			80,578			76,763
	Northeast Region	20,721			19,806			45,331			43,441
	Southwest Region	13,859			13,293			40,949			39,012
	Non-Mature Communities/Other	33,064			27,070			121,756			106,256
	Total consolidated rental income	$	203,608		$	190,379		$	599,045		$	563,293
	Reportable apartment home segment NOI
	Same-Store Communities
	West Region	$	49,110		$	45,699		$	136,587		$	126,860
	Mid-Atlantic Region	27,622			27,629			83,581			83,287
	Southeast Region	17,480			16,560			53,329			49,866
	Northeast Region	15,571			14,678			33,361			31,409
	Southwest Region	8,509			7,983			25,130			23,751
	Non-Mature Communities/Other	21,522			16,094			80,342			67,439
	Total consolidated NOI	139,814			128,643			412,330			382,612
	Reconciling items:
	Joint venture management and other fees	3,165			3,207			9,599			9,347
	Property management	(5,599		)	(5,236		)	(16,474		)	(15,491		)
	Other operating expenses	(2,012		)	(1,787		)	(6,118		)	(5,237		)
	Real estate depreciation and amortization	(89,339		)	(84,266		)	(266,748		)	(252,839		)
	General and administrative	(11,554		)	(11,364		)	(36,078		)	(30,706		)
	Casualty-related recoveries/(charges), net	—			6,460			(500		)	12,253
	Other depreciation and amortization	(1,385		)	(1,176		)	(3,658		)	(3,460		)
	Income/(loss) from unconsolidated entities	(939		)	(3,794		)	(4,932		)	(6,081		)
	Interest expense	(33,087		)	(30,939		)	(97,662		)	(92,723		)
	Interest and other income/(expense), net	9,061			829			11,902			3,291
	Tax benefit/(expense), net	2,490			2,658			8,049			7,314
	Gain/(loss) on sale of real estate owned, net of tax	31,377			—			82,380			—
	Net (income)/loss attributable to redeemable noncontrolling interests in the Operating Partnership	(1,447		)	(84		)	(3,171		)	(198		)
	Net (income)/loss attributable to noncontrolling interests	4			37			(2		)	30
	Net income/(loss) attributable to UDR, Inc.	$	40,549		$	3,188		$	88,917		$	8,112
	(a)	Same-Store Community population consisted of 36,268 apartment homes.
	(b)	Same-Store Community population consisted of 35,177 apartment homes.
	The following table details the assets of UDR’s reportable segments as of September 30, 2014 and December 31, 2013 (dollars in thousands):
		September 30,			December 31,
		2014			2013
	Reportable apartment home segment assets:
	Same-Store Communities:
	West Region	$	2,591,838		$	2,412,091
	Mid-Atlantic Region	1,404,730			1,395,772
	Southeast Region	783,641			785,134
	Northeast Region	1,073,905			1,066,260
	Southwest Region	438,982			434,875
	Non-Mature Communities/Other	2,135,195			2,113,845
	Total assets	8,428,291			8,207,977
	Accumulated depreciation	(2,379,033		)	(2,208,794		)
	Total assets — net book value	6,049,258			5,999,183
	Reconciling items:
	Cash and cash equivalents	14,605			30,249
Restricted cash	23,969			22,796
Deferred financing costs, net	24,344			26,924
Notes receivable, net	18,318			83,033
Investment in and advances to unconsolidated joint ventures, net	650,441			507,655
Other assets	117,153			137,882
Total consolidated assets	$	6,898,088		$	6,807,722
Capital expenditures related to our Same-Store Communities totaled $15.1 million and $36.5 million for the three and nine months ended September 30, 2014, respectively, and $14.5 million and $34.6 million for the three and nine months ended September 30, 2013, respectively. Capital expenditures related to our Non-Mature Communities/Other totaled $1.3 million and $5.0 million for the three and nine months ended September 30, 2014, respectively, and $1.6 million and $4.8 million for the three and nine months ended September 30, 2013, respectively.
Markets included in the above geographic segments are as follows:
i.	West Region — San Francisco, Orange County, Seattle, Monterey Peninsula, Los Angeles, Other Southern California, and Portland
ii.	Mid-Atlantic Region — Metropolitan D.C., Baltimore, Richmond, Norfolk, and Other Mid-Atlantic
iii.	Northeast Region — New York and Boston
iv.	Southeast Region — Tampa, Orlando, Nashville, and Other Florida
v.	Southwest Region — Dallas and Austin

Reportable_Segments_UNITED_DOM

Reportable Segments (UNITED DOMINION REALTY, L.P.)	9 Months Ended
	Sep. 30, 2014
Entity Information [Line Items]	'
REPORTABLE SEGMENTS	'
	REPORTABLE SEGMENTS
	GAAP guidance requires that segment disclosures present the measure(s) used by the chief operating decision maker to decide how to allocate resources and for purposes of assessing such segments’ performance. UDR’s chief operating decision maker is comprised of several members of its executive management team who use several generally accepted industry financial measures to assess the performance of the business for our reportable operating segments.
	UDR owns and operates multifamily apartment communities that generate rental and other property related income through the leasing of apartment homes to a diverse base of tenants. The primary financial measures for UDR’s apartment communities are rental income and net operating income (“NOI”). Rental income represents gross market rent less adjustments for concessions, vacancy loss and bad debt. NOI is defined as rental income less direct property rental expenses. Rental expenses include real estate taxes, insurance, personnel, utilities, repairs and maintenance, administrative and marketing. Excluded from NOI is property management expense, which is calculated as 2.75% of property revenue to cover the regional supervision and accounting costs related to consolidated property operations, and land rent. UDR’s chief operating decision maker utilizes NOI as the key measure of segment profit or loss.
	UDR’s two reportable segments are Same-Store Communities and Non-Mature Communities/Other:
	•	Same-Store Communities represent those communities acquired, developed, and stabilized prior to July 1, 2013 for quarter-to-date comparison and January 1, 2013 for year-to-date comparison and held as of September 30, 2014. A comparison of operating results from the prior year is meaningful as these communities were owned and had stabilized occupancy and operating expenses as of the beginning of the prior period, there is no plan to conduct substantial redevelopment activities, and the community is not held for disposition within the current year. A community is considered to have stabilized occupancy once it achieves 90% occupancy for at least three consecutive months.
	•	Non-Mature Communities/Other represent those communities that do not meet the criteria to be included in Same-Store Communities, including, but not limited to, recently acquired, developed and redeveloped properties, and the non-apartment components of mixed use properties.
	Management evaluates the performance of each of our apartment communities on a Same-Store Community and Non-Mature Community/Other basis, as well as individually and geographically. This is consistent with the aggregation criteria under GAAP as each of our apartment communities generally has similar economic characteristics, facilities, services, and tenants. Therefore, the Company’s reportable segments have been aggregated by geography in a manner identical to that which is provided to the chief operating decision maker.
	All revenues are from external customers and no single tenant or related group of tenants contributed 10% or more of UDR’s total revenues during the three and nine months ended September 30, 2014 and 2013.
	The following table details rental income and NOI from continuing and discontinued operations for UDR’s reportable segments for the three and nine months ended September 30, 2014 and 2013, and reconciles NOI to Net Income/(Loss) Attributable to UDR, Inc. in the Consolidated Statements of Operations (dollars in thousands):
		Three Months Ended September 30, (a)						Nine Months Ended September 30, (b)
		2014			2013			2014			2013
	Reportable apartment home segment rental income
	Same-Store Communities
	West Region	$	68,275		$	64,195		$	189,075		$	177,884
	Mid-Atlantic Region	40,479			40,164			121,356			119,937
	Southeast Region	27,210			25,851			80,578			76,763
	Northeast Region	20,721			19,806			45,331			43,441
	Southwest Region	13,859			13,293			40,949			39,012
	Non-Mature Communities/Other	33,064			27,070			121,756			106,256
	Total consolidated rental income	$	203,608		$	190,379		$	599,045		$	563,293
	Reportable apartment home segment NOI
	Same-Store Communities
	West Region	$	49,110		$	45,699		$	136,587		$	126,860
	Mid-Atlantic Region	27,622			27,629			83,581			83,287
	Southeast Region	17,480			16,560			53,329			49,866
	Northeast Region	15,571			14,678			33,361			31,409
	Southwest Region	8,509			7,983			25,130			23,751
	Non-Mature Communities/Other	21,522			16,094			80,342			67,439
	Total consolidated NOI	139,814			128,643			412,330			382,612
	Reconciling items:
	Joint venture management and other fees	3,165			3,207			9,599			9,347
	Property management	(5,599		)	(5,236		)	(16,474		)	(15,491		)
	Other operating expenses	(2,012		)	(1,787		)	(6,118		)	(5,237		)
	Real estate depreciation and amortization	(89,339		)	(84,266		)	(266,748		)	(252,839		)
	General and administrative	(11,554		)	(11,364		)	(36,078		)	(30,706		)
	Casualty-related recoveries/(charges), net	—			6,460			(500		)	12,253
	Other depreciation and amortization	(1,385		)	(1,176		)	(3,658		)	(3,460		)
	Income/(loss) from unconsolidated entities	(939		)	(3,794		)	(4,932		)	(6,081		)
	Interest expense	(33,087		)	(30,939		)	(97,662		)	(92,723		)
	Interest and other income/(expense), net	9,061			829			11,902			3,291
	Tax benefit/(expense), net	2,490			2,658			8,049			7,314
	Gain/(loss) on sale of real estate owned, net of tax	31,377			—			82,380			—
	Net (income)/loss attributable to redeemable noncontrolling interests in the Operating Partnership	(1,447		)	(84		)	(3,171		)	(198		)
	Net (income)/loss attributable to noncontrolling interests	4			37			(2		)	30
	Net income/(loss) attributable to UDR, Inc.	$	40,549		$	3,188		$	88,917		$	8,112
	(a)	Same-Store Community population consisted of 36,268 apartment homes.
	(b)	Same-Store Community population consisted of 35,177 apartment homes.
	The following table details the assets of UDR’s reportable segments as of September 30, 2014 and December 31, 2013 (dollars in thousands):
		September 30,			December 31,
		2014			2013
	Reportable apartment home segment assets:
	Same-Store Communities:
	West Region	$	2,591,838		$	2,412,091
	Mid-Atlantic Region	1,404,730			1,395,772
	Southeast Region	783,641			785,134
	Northeast Region	1,073,905			1,066,260
	Southwest Region	438,982			434,875
	Non-Mature Communities/Other	2,135,195			2,113,845
	Total assets	8,428,291			8,207,977
	Accumulated depreciation	(2,379,033		)	(2,208,794		)
	Total assets — net book value	6,049,258			5,999,183
	Reconciling items:
	Cash and cash equivalents	14,605			30,249
Restricted cash	23,969			22,796
Deferred financing costs, net	24,344			26,924
Notes receivable, net	18,318			83,033
Investment in and advances to unconsolidated joint ventures, net	650,441			507,655
Other assets	117,153			137,882
Total consolidated assets	$	6,898,088		$	6,807,722
Capital expenditures related to our Same-Store Communities totaled $15.1 million and $36.5 million for the three and nine months ended September 30, 2014, respectively, and $14.5 million and $34.6 million for the three and nine months ended September 30, 2013, respectively. Capital expenditures related to our Non-Mature Communities/Other totaled $1.3 million and $5.0 million for the three and nine months ended September 30, 2014, respectively, and $1.6 million and $4.8 million for the three and nine months ended September 30, 2013, respectively.
Markets included in the above geographic segments are as follows:
i.	West Region — San Francisco, Orange County, Seattle, Monterey Peninsula, Los Angeles, Other Southern California, and Portland
ii.	Mid-Atlantic Region — Metropolitan D.C., Baltimore, Richmond, Norfolk, and Other Mid-Atlantic
iii.	Northeast Region — New York and Boston
iv.	Southeast Region — Tampa, Orlando, Nashville, and Other Florida
v.	Southwest Region — Dallas and Austin
United Dominion Reality L.P. [Member]	'
Entity Information [Line Items]	'
REPORTABLE SEGMENTS	'
	REPORTABLE SEGMENTS
	GAAP guidance requires that segment disclosures present the measure(s) used by the chief operating decision maker to decide how to allocate resources and for purposes of assessing such segments’ performance. The Operating Partnership has the same chief operating decision maker as that of its parent, the General Partner. The chief operating decision maker consists of several members of UDR’s executive management team who use several generally accepted industry financial measures to assess the performance of the business for our reportable operating segments.
	The Operating Partnership owns and operates multifamily apartment communities throughout the United States that generate rental and other property related income through the leasing of apartment homes to a diverse base of tenants. The primary financial measures of the Operating Partnership’s apartment communities are rental income and net operating income (“NOI”), and are included in the chief operating decision maker’s assessment of the Operating Partnership’s performance on a consolidated basis. Rental income represents gross market rent less adjustments for concessions, vacancy loss and bad debt. NOI is defined as total revenues less direct property operating expenses. Rental expenses include real estate taxes, insurance, personnel, utilities, repairs and maintenance, administrative and marketing. Excluded from NOI is property management expense which is calculated as 2.75% of property revenue to cover the regional supervision and accounting costs related to consolidated property operations, and land rent. The chief operating decision maker of the General Partner utilizes NOI as the key measure of segment profit or loss.
	The Operating Partnership’s two reportable segments are Same-Store Communities and Non-Mature Communities/Other:
	•	Same-Store Communities represent those communities acquired, developed, and stabilized prior to July 1, 2013 for quarter-to-date comparison and January 1, 2013 for year-to-date comparison and held as of September 30, 2014. A comparison of operating results from the prior year is meaningful as these communities were owned and had stabilized occupancy and operating expenses as of the beginning of the prior period, there is no plan to conduct substantial redevelopment activities, and the community is not held for disposition within the current year. A community is considered to have stabilized occupancy once it achieves 90% occupancy for at least three consecutive months.
	•	Non-Mature Communities/Other represent those communities that do not meet the criteria to be included in Same-Store Communities, including, but not limited to, recently acquired, developed and redeveloped properties, and the non-apartment components of mixed use properties.
	Management of the General Partner evaluates the performance of each of the Operating Partnership’s apartment communities on a Same-Store Community and Non-Mature Community/Other basis, as well as individually and geographically. This is consistent with the aggregation criteria under GAAP as each of the apartment communities generally has similar economic characteristics, facilities, services, and tenants. Therefore, the Operating Partnership’s reportable segments have been aggregated by geography in a manner identical to that which is provided to the chief operating decision maker.
	All revenues are from external customers and no single tenant or related group of tenants contributed 10% or more of the Operating Partnership’s total revenues during the three and nine months ended September 30, 2014 and 2013.
	The following table details rental income and NOI from continuing and discontinued operations for the Operating Partnership’s reportable segments for the three and nine months ended September 30, 2014 and 2013, and reconciles NOI to Net income/(loss) attributable to OP unitholders in the Consolidated Statements of Operations (dollars in thousands):
		Three Months Ended September 30, (a)						Nine Months Ended September 30, (b)
		2014			2013			2014			2013
	Reportable apartment home segment rental income
	Same-Store Communities
	West Region	$	49,279		$	46,246		$	144,252		$	135,418
	Mid-Atlantic Region	17,169			17,105			51,779			51,095
	Southeast Region	11,368			10,841			33,753			32,177
	Northeast Region	14,968			14,331			28,410			27,414
	Southwest Region	6,667			6,508			19,873			19,098
	Non-Mature Communities/Other	7,993			8,966			36,589			41,564
	Total consolidated rental income	$	107,444		$	103,997		$	314,656		$	306,766
	Reportable apartment home segment NOI
	Same-Store Communities
	West Region	$	35,801		$	33,307		$	105,375		$	97,533
	Mid-Atlantic Region	11,422			11,483			34,888			34,689
	Southeast Region	7,327			6,957			22,286			20,898
	Northeast Region	11,609			10,789			21,448			20,083
	Southwest Region	4,192			4,040			12,578			11,987
	Non-Mature Communities/Other	5,402			5,417			26,563			29,383
	Total consolidated NOI	75,753			71,993			223,138			214,573
	Reconciling items:
	Property management	(2,955		)	(2,860		)	(8,653		)	(8,436		)
	Other operating expenses	(1,484		)	(1,405		)	(4,371		)	(4,215		)
	Real estate depreciation and amortization	(45,043		)	(44,857		)	(134,011		)	(135,552		)
	General and administrative	(6,939		)	(6,855		)	(21,368		)	(18,324		)
	Casualty-related recoveries/(charges), net	—			3,807			(500		)	8,083
	Interest expense	(10,457		)	(8,773		)	(30,629		)	(27,085		)
	Gain/(loss) on sale of real estate owned	—			—			40,687			—
	Net (income)/loss attributable to noncontrolling interests	(238		)	(39		)	(697		)	(151		)
	Net income/(loss) attributable to OP unitholders	$	8,637		$	11,011		$	63,596		$	28,893
	(a)	Same-store consists of 19,518 apartment homes.
	(b)	Same-store consists of 19,010 apartment homes.
	The following table details the assets of the Operating Partnership’s reportable segments as of September 30, 2014 and December 31, 2013 (dollars in thousands):
		September 30,			December 31, 2013
		2014
	Reportable apartment home segment assets
	Same-Store Communities
	West Region	$	1,742,559		$	1,733,144
	Mid-Atlantic Region	710,277			706,447
	Southeast Region	331,727			328,150
	Northeast Region	776,310			770,937
	Southwest Region	227,886			226,252
	Non-Mature Communities/Other	430,464			423,550
	Total assets	4,219,223			4,188,480
	Accumulated depreciation	(1,358,123		)	(1,241,574		)
	Total assets - net book value	2,861,100			2,946,906
	Reconciling items:
	Cash and cash equivalents	1,484			1,897
	Restricted cash	13,989			13,526
	Deferred financing costs, net	4,783			5,848
	Other assets	25,070			25,064
	Total consolidated assets	$	2,906,426		$	2,993,241
	Capital expenditures related to the Operating Partnership’s Same-Store Communities totaled $8.6 million and $20.0 million for the three and nine months ended September 30, 2014, respectively, and $6.9 million and $18.5 million for the three and nine months ended September 30, 2013, respectively. Capital expenditures related to the Operating Partnership’s Non-Mature Communities/Other totaled $137,000 and $555,000 for the three and nine months ended September 30, 2014, respectively, and $436,000 and $1.5 million for the three and nine months ended September 30, 2013, respectively.
	Markets included in the above geographic segments are as follows:
i.	West Region — San Francisco, Orange County, Seattle, Monterey Peninsula, Los Angeles, Other Southern California, and Portland
ii.	Mid-Atlantic Region — Metropolitan D.C. and Baltimore
iii.	Northeast Region — New York and Boston
iv.	Southeast Region — Nashville, Tampa, and Other Florida
v.	Southwest Region — Dallas

Significant_Accounting_Policie2

Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2014
Accounting Policies [Abstract]	'
Comprehensive Income, Policy [Policy Text Block]	'
	Comprehensive Income/(Loss)
	Comprehensive income/(loss), which is defined as the change in equity during each period from transactions and other events and circumstances from nonowner sources, including all changes in equity during a period except for those resulting from investments by or distributions to stockholders, is displayed in the accompanying Consolidated Statements of Comprehensive Income/(Loss). For the three and nine months ended September 30, 2014 and 2013, the Company’s other comprehensive income/(loss) consisted of the gain/(loss) (effective portion) on derivative instruments that are designated as and qualify as cash flow hedges, (gain)/loss on derivative instruments reclassified from other comprehensive income/(loss) into earnings, and the allocation of other comprehensive income/(loss) to redeemable noncontrolling interests. The (gain)/loss on derivative instruments reclassified from other comprehensive income/(loss) is included in Interest expense on the Consolidated Statements of Operations. See Note 10, Derivatives and Hedging Activity, for further discussion. The allocation of other comprehensive income/(loss) to redeemable noncontrolling interests was $57,000 and $163,000 during the three and nine months ended September 30, 2014, respectively, and $45,000 and $196,000 during the three and nine months ended September 30, 2013, respectively.
New Accounting Pronouncements, Policy [Policy Text Block]	'
	Recent Accounting Pronouncements
Revenue and real estate sales gain recognition	'
	Revenue and Real Estate Sales Gain Recognition
	Rental income related to leases is recognized on an accrual basis when due from residents and tenants in accordance with GAAP. Rental payments are generally due on a monthly basis and recognized when earned. The Company recognizes interest income, management and other fees and incentives when earned, and the amounts are fixed and determinable.
	For sale transactions meeting the requirements for full accrual profit recognition, we remove the related assets and liabilities from our Consolidated Balance Sheets and record the gain or loss in the period the transaction closes. For sale transactions that do not meet the full accrual sale criteria due to our continuing involvement, we evaluate the nature of the continuing involvement and account for the transaction under an alternate method of accounting. Unless certain limited criteria are met, non-monetary transactions, including property exchanges, are accounted for at fair value.
	Sales to entities in which we retain or otherwise own an interest are accounted for as partial sales. If all other requirements for recognizing profit under the full accrual method have been satisfied and no other forms of continuing involvement are present, we recognize profit proportionate to the outside interest in the buyer and defer the gain on the interest we retain. The Company recognizes any deferred gain when the property is sold to a third party. In transactions accounted for by us as partial sales, we determine if the buyer of the majority equity interest in the venture was provided a preference as to cash flows in either an operating or a capital waterfall. If a cash flow preference has been provided, we recognize profit only to the extent that proceeds from the sale of the majority equity interest exceed costs related to the entire propert
Income Taxes	'
	Income Taxes
	Due to the structure of the Company as a REIT and the nature of the operations for the operating properties, no provision for federal income taxes has been provided for at UDR. Historically, the Company has generally incurred only state and local excise and franchise taxes. UDR has elected for certain consolidated subsidiaries to be treated as taxable REIT subsidiaries (“TRS”), primarily those engaged in development activities.
	Income taxes for our TRS, RE3, are accounted for under the asset and liability method. Deferred tax assets and liabilities are recognized for future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax basis. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities from a change in tax rate is recognized in earnings in the period of the enactment date. The Company’s deferred tax assets are generally the result of differing depreciable lives on capitalized assets and timing of expense recognition for certain accrued liabilities. As of September 30, 2014, UDR’s net deferred tax asset was $9.1 million (net of a valuation allowance of $1.4 million), which is included in Other assets on the Consolidated Balance Sheets.
	GAAP defines a recognition threshold and measurement attribute for the financial statement recognition and measurement of a tax position taken or expected to be taken in a tax return. GAAP also provides guidance on derecognition, classification, interest and penalties, accounting for interim periods, disclosure and transition.
	The Company recognizes its tax positions and evaluates them using a two-step process. First, UDR determines whether a tax position is more likely than not (greater than 50 percent probability) to be sustained upon examination, including resolution of any related appeals or litigation processes, based on the technical merits of the position. Second, the Company will determine the amount of benefit to recognize and record the amount that is more likely than not to be realized upon ultimate settlement.
	UDR had no material unrecognized tax benefit, accrued interest or penalties at September 30, 2014. UDR and its subsidiaries are subject to federal income tax as well as income tax of various state and local jurisdictions. The tax years 2010 through 2013 remain open to examination by tax jurisdictions to which we are subject. When applicable, UDR recognizes interest and/or penalties related to uncertain tax positions in Tax benefit/(expense), net on the Consolidated Statements of Operations.
Policy Loans Receivable, Policy [Policy Text Block]	'
	Notes Receivable
	The following table summarizes our notes receivable, net as of September 30, 2014 and December 31, 2013 (dollars in thousands):
		Balance outstanding
		September 30, 2014		December 31, 2013		Interest rate at September 30, 2014
	Note due June 2014 (a)	$	—	$	40,800	—	%
	Note due February 2017 (b)	15,818		14,580		10	%
	Note due July 2017 (c)	2,500		1,400		8	%
	Note due June 2022 (net of discount of $0 and $247, respectively) (d)	—		26,253		—	%
	Total notes receivable, net	$	18,318	$	83,033
	(a) In the fourth quarter of 2013, in conjunction with the sale of its 95% interest in the Lodge at Stoughton, one of its unconsolidated joint ventures, the Company provided the buyer with a $40.8 million loan secured by the property at LIBOR plus a spread of 350 basis points with two three-month extension options at increased rates and a financing fee. In June 2014, the note was paid in full.
	(b) The Company has a secured note receivable with an unaffiliated third party with an aggregate commitment of $15.8 million, which bears an interest rate of 10.00% per annum. During the nine months ended September 30, 2014, the Company loaned an additional $1.2 million under the note. Interest payments are due monthly. The note matures at the earliest of the following: (a) the closing of any private or public capital raising in the amount of $5.0 million or greater; (b) an acquisition; (c) acceleration in the event of default; or (d) the fifth anniversary of the date of the note (February 2017).
	(c) The Company has a secured note receivable with an unaffiliated third party with an aggregate commitment of $2.5 million, which bears an interest rate of 8.00% per annum. During the nine months ended September 30, 2014, the Company loaned an additional $1.1 million. Interest payments are due monthly. The note matures at the earliest of the following: (a) the closing of any private or public capital raising in the amount of $5.0 million or greater; (b) an acquisition; (c) acceleration in the event of default; or (d) the fifth anniversary of the date of the note (July 2017).
	(d) In 2012, the Company purchased a "B" Note secured by a first mortgage on a class A community in West Los Angeles. The $26.5 million loan was purchased at a yield of 7.25% and bore a coupon rate of 7.00%. Interest payments are due monthly and the note is due June 2022. The discount is amortized using the effective interest method. In July 2014, the Company received proceeds of $36.0 million from the repayment of this note, resulting in a net gain of approximately $8.4 million, which is included in Interest and other income/(expense), net on the Consolidated Statements of Operations.
	The Company recognized $0.4 million and $3.0 million of interest income from these notes receivable during the three and nine months ended September 30, 2014, respectively, and $1.1 million and $3.1 million during the three and nine months ended September 30, 2013, respectively. Included in the three and nine months ended September 30, 2013 are $184,000 and $547,000 of related party interest income, respectively. Interest income is included in Interest and other income/(expense), net on the Consolidated Statements of Operations.

Significant_Accounting_Policie3

Significant Accounting Policies (UNITED DOMINION REALTY, L.P.) (Policies)	9 Months Ended
	Sep. 30, 2014
Entity Information [Line Items]	'
New Accounting Pronouncements, Policy [Policy Text Block]	'
	Recent Accounting Pronouncements
Revenue and real estate sales gain recognition	'
	Revenue and Real Estate Sales Gain Recognition
	Rental income related to leases is recognized on an accrual basis when due from residents and tenants in accordance with GAAP. Rental payments are generally due on a monthly basis and recognized when earned. The Company recognizes interest income, management and other fees and incentives when earned, and the amounts are fixed and determinable.
	For sale transactions meeting the requirements for full accrual profit recognition, we remove the related assets and liabilities from our Consolidated Balance Sheets and record the gain or loss in the period the transaction closes. For sale transactions that do not meet the full accrual sale criteria due to our continuing involvement, we evaluate the nature of the continuing involvement and account for the transaction under an alternate method of accounting. Unless certain limited criteria are met, non-monetary transactions, including property exchanges, are accounted for at fair value.
	Sales to entities in which we retain or otherwise own an interest are accounted for as partial sales. If all other requirements for recognizing profit under the full accrual method have been satisfied and no other forms of continuing involvement are present, we recognize profit proportionate to the outside interest in the buyer and defer the gain on the interest we retain. The Company recognizes any deferred gain when the property is sold to a third party. In transactions accounted for by us as partial sales, we determine if the buyer of the majority equity interest in the venture was provided a preference as to cash flows in either an operating or a capital waterfall. If a cash flow preference has been provided, we recognize profit only to the extent that proceeds from the sale of the majority equity interest exceed costs related to the entire propert
Comprehensive Income, Policy [Policy Text Block]	'
	Comprehensive Income/(Loss)
	Comprehensive income/(loss), which is defined as the change in equity during each period from transactions and other events and circumstances from nonowner sources, including all changes in equity during a period except for those resulting from investments by or distributions to stockholders, is displayed in the accompanying Consolidated Statements of Comprehensive Income/(Loss). For the three and nine months ended September 30, 2014 and 2013, the Company’s other comprehensive income/(loss) consisted of the gain/(loss) (effective portion) on derivative instruments that are designated as and qualify as cash flow hedges, (gain)/loss on derivative instruments reclassified from other comprehensive income/(loss) into earnings, and the allocation of other comprehensive income/(loss) to redeemable noncontrolling interests. The (gain)/loss on derivative instruments reclassified from other comprehensive income/(loss) is included in Interest expense on the Consolidated Statements of Operations. See Note 10, Derivatives and Hedging Activity, for further discussion. The allocation of other comprehensive income/(loss) to redeemable noncontrolling interests was $57,000 and $163,000 during the three and nine months ended September 30, 2014, respectively, and $45,000 and $196,000 during the three and nine months ended September 30, 2013, respectively.
Income taxes	'
	Income Taxes
	Due to the structure of the Company as a REIT and the nature of the operations for the operating properties, no provision for federal income taxes has been provided for at UDR. Historically, the Company has generally incurred only state and local excise and franchise taxes. UDR has elected for certain consolidated subsidiaries to be treated as taxable REIT subsidiaries (“TRS”), primarily those engaged in development activities.
	Income taxes for our TRS, RE3, are accounted for under the asset and liability method. Deferred tax assets and liabilities are recognized for future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax basis. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities from a change in tax rate is recognized in earnings in the period of the enactment date. The Company’s deferred tax assets are generally the result of differing depreciable lives on capitalized assets and timing of expense recognition for certain accrued liabilities. As of September 30, 2014, UDR’s net deferred tax asset was $9.1 million (net of a valuation allowance of $1.4 million), which is included in Other assets on the Consolidated Balance Sheets.
	GAAP defines a recognition threshold and measurement attribute for the financial statement recognition and measurement of a tax position taken or expected to be taken in a tax return. GAAP also provides guidance on derecognition, classification, interest and penalties, accounting for interim periods, disclosure and transition.
	The Company recognizes its tax positions and evaluates them using a two-step process. First, UDR determines whether a tax position is more likely than not (greater than 50 percent probability) to be sustained upon examination, including resolution of any related appeals or litigation processes, based on the technical merits of the position. Second, the Company will determine the amount of benefit to recognize and record the amount that is more likely than not to be realized upon ultimate settlement.
	UDR had no material unrecognized tax benefit, accrued interest or penalties at September 30, 2014. UDR and its subsidiaries are subject to federal income tax as well as income tax of various state and local jurisdictions. The tax years 2010 through 2013 remain open to examination by tax jurisdictions to which we are subject. When applicable, UDR recognizes interest and/or penalties related to uncertain tax positions in Tax benefit/(expense), net on the Consolidated Statements of Operations.
United Dominion Reality L.P. [Member]	'
Entity Information [Line Items]	'
New Accounting Pronouncements, Policy [Policy Text Block]	'
	Recent Accounting Pronouncements
	In April 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2014-08, Reporting Discontinued Operations and Disclosures of Disposals of Components of an Entity, which incorporates a requirement that a disposition represent a strategic shift in an entity’s operations into the definition of a discontinued operation. In accordance with the ASU, a discontinued operation represents (1) a component of an entity or group of components that has been disposed of or is classified as held for sale in a single transaction and represents a strategic shift that has or will have a major effect on an entity’s financial results, or (2) an acquired business that is classified as held for sale on the date of acquisition. A strategic shift could include a disposal of (1) a separate major line of business, (2) a separate major geographic area of operations, (3) a major equity method investment, or (4) other major parts of an entity. The standard requires prospective application and will be effective for interim and annual periods beginning on or after December 15, 2014, with early adoption permitted. The early adoption provision excludes components of an entity that were sold or classified as held for sale prior to the adoption of the standard.
	The Operating Partnership elected to early adopt this standard effective January 1, 2014, which had a significant impact on the Operating Partnership’s consolidated financial statements as further discussed in Note 4, Discontinued Operations. Subsequent to the Operating Partnership’s adoption of ASU 2014-08, the sale of real estate that does not meet the definition of a discontinued operation under the standard is included in Gain/(loss) on sale of real estate owned on the Consolidated Statements of Operations.
	In May 2014, FASB issued ASU No. 2014-09, Revenue from Contracts with Customers. The standard provides companies with a single model for use in accounting for revenue arising from contracts with customers and supersedes current revenue recognition guidance, including industry-specific revenue guidance. The updated standard will replace most existing revenue recognition guidance in U.S. GAAP when it becomes effective. The standard specifically excludes lease contracts. The ASU allows for the use of either the full or modified retrospective transition method, and the standard will be effective for the Operating Partnership on January 1, 2017; early adoption is not permitted. The Operating Partnership has not yet selected a transition method and we are currently evaluating the effect that the updated standard will have on its consolidated financial statements and related disclosures.
Revenue and real estate sales gain recognition	'
	Revenue and Real Estate Sales Gain Recognition
	Rental income related to leases is recognized on an accrual basis when due from residents and tenants in accordance with GAAP. Rental payments are generally due on a monthly basis and recognized when earned. The Operating Partnership recognizes interest income, fees and incentives when earned, fixed and determinable.
	For sale transactions meeting the requirements for full accrual profit recognition, we remove the related assets and liabilities from our Consolidated Balance Sheets and record the gain or loss in the period the transaction closes. For sale transactions that do not meet the full accrual sale criteria due to our continuing involvement, we evaluate the nature of the continuing involvement and account for the transaction under an alternate method of accounting. Unless certain limited criteria are met, non-monetary transactions, including property exchanges, are accounted for at fair value.
	Sales to entities in which we or our General Partner retain or otherwise own an interest are accounted for as partial sales. If all other requirements for recognizing profit under the full accrual method have been satisfied and no other forms of continuing involvement are present, we recognize profit proportionate to the outside interest in the buyer and defer the gain on the interest we or our General Partner retain. The Operating Partnership recognizes any deferred gain when the property is sold to a third party. In transactions accounted by us as partial sales, we determine if the buyer of the majority equity interest in the venture was provided a preference as to cash flows in either an operating or a capital waterfall. If a cash flow preference has been provided, we recognize profit only to the extent that proceeds from the sale of the majority equity interest exceed costs related to the entire property.
Comprehensive Income, Policy [Policy Text Block]	'
	Comprehensive Income/(Loss)
	Comprehensive income/(loss), which is defined as the change in equity during each period from transactions and other events and circumstances from nonowner sources, including all changes in equity during a period except for those resulting from investments by or distributions to unitholders, is displayed in the accompanying Consolidated Statements of Comprehensive Income/(Loss). For the three and nine months ended September 30, 2014 and 2013, the Operating Partnership’s other comprehensive income/(loss) consisted of the gain/(loss) (effective portion) on derivative instruments that are designated as and qualify as cash flow hedges and (gain)/loss reclassified from other comprehensive income/(loss) into earnings. The (gain)/loss reclassified from other comprehensive income/(loss) is included in Interest expense on the Consolidated Statements of Operations. See Note 8, Derivatives and Hedging Activity, for further discussion.
Income taxes	'
	Income Taxes
	The taxable income or loss of the Operating Partnership is reported on the tax returns of the partners. Accordingly, no provision has been made in the accompanying financial statements for federal or state income taxes on income that is passed through to the partners. However, any state or local revenue, excise or franchise taxes that result from the operating activities of the Operating Partnership are recorded at the entity level. The Operating Partnership’s tax returns are subject to examination by federal and state taxing authorities. Net income for financial reporting purposes differs from the net income for income tax reporting purposes primarily due to temporary differences, principally real estate depreciation and the tax deferral of certain gains on property sales. The differences in depreciation result from differences in the book and tax basis of certain real estate assets and the differences in the methods of depreciation and lives of the real estate assets.
	The Operating Partnership evaluates the accounting and disclosure of tax positions taken or expected to be taken in the course of preparing the Operating Partnership’s tax returns to determine whether the tax positions are “more-likely-than-not” of being sustained by the applicable tax authority. Tax positions not deemed to meet the more-likely-than-not threshold would be recorded as a tax benefit or expense in the current year. Management of the Operating Partnership is required to analyze all open tax years, as defined by the statute of limitations, for all major jurisdictions, which include federal and certain states. The Operating Partnership has no examinations in progress and none are expected at this time.
	Management of the Operating Partnership has reviewed all open tax years (2010 through 2013) of tax jurisdictions and concluded there is no tax liability resulting from unrecognized tax benefits relating to uncertain income tax positions taken or expected to be taken in future tax returns.
Earnings per OP unit	'
	Basic income/(loss) per OP Unit is computed by dividing net income/(loss) attributable to general and limited partner unitholders by the weighted average number of general and limited partner units (including redeemable OP Units) outstanding during the period. Diluted income/(loss) per OP Unit reflects the potential dilution that could occur if securities or other contracts to issue OP Units were exercised or converted into OP Units or resulted in the issuance of OP Units and then shared in the income/(loss) of the Operating Partnership. For the three and nine months ended September 30, 2014 and 2013, there were no dilutive instruments outstanding, and therefore, diluted income/(loss) per OP Unit and basic income/(loss) per OP Unit are the same.

Significant_Accounting_Policie4

Significant Accounting Policies (Tables)	9 Months Ended
	Sep. 30, 2014
Accounting Policies [Abstract]	'
Notes receivable	'
	The following table summarizes our notes receivable, net as of September 30, 2014 and December 31, 2013 (dollars in thousands):
		Balance outstanding
		September 30, 2014		December 31, 2013		Interest rate at September 30, 2014
	Note due June 2014 (a)	$	—	$	40,800	—	%
	Note due February 2017 (b)	15,818		14,580		10	%
	Note due July 2017 (c)	2,500		1,400		8	%
	Note due June 2022 (net of discount of $0 and $247, respectively) (d)	—		26,253		—	%
	Total notes receivable, net	$	18,318	$	83,033

Real_Estate_Owned_Tables

Real Estate Owned (Tables)	9 Months Ended
	Sep. 30, 2014
Real Estate [Abstract]	'
Summary of carrying amounts for real estate owned (at cost)	'
	The following table summarizes the carrying amounts for our real estate owned (at cost) as of September 30, 2014 and December 31, 2013 (dollars in thousands):
		September 30,			December 31, 2013
		2014
	Land and land improvements	$	1,955,007		$	1,847,127
	Depreciable property — held and used:
	Building, improvements, and furniture, fixtures and equipment	6,151,677			5,876,717
	Under development:
	Land and land improvements	47,038			110,769
	Building, improvements, and furniture, fixtures and equipment	274,569			356,644
	Real estate held for disposition:
	Land and land improvements	—			10,751
	Building, improvements, and furniture, fixtures and equipment	—			5,969
	Real estate owned	8,428,291			8,207,977
	Accumulated depreciation	(2,379,033		)	(2,208,794		)
	Real estate owned, net	$	6,049,258		$	5,999,183

Real_Estate_Owned_UNITED_DOMIN1

Real Estate Owned (UNITED DOMINION REALTY, L.P.) (Tables)	9 Months Ended
	Sep. 30, 2014
Entity Information [Line Items]	'
Summary of carrying amounts for real estate owned (at cost)	'
	The following table summarizes the carrying amounts for our real estate owned (at cost) as of September 30, 2014 and December 31, 2013 (dollars in thousands):
		September 30,			December 31, 2013
		2014
	Land and land improvements	$	1,955,007		$	1,847,127
	Depreciable property — held and used:
	Building, improvements, and furniture, fixtures and equipment	6,151,677			5,876,717
	Under development:
	Land and land improvements	47,038			110,769
	Building, improvements, and furniture, fixtures and equipment	274,569			356,644
	Real estate held for disposition:
	Land and land improvements	—			10,751
	Building, improvements, and furniture, fixtures and equipment	—			5,969
	Real estate owned	8,428,291			8,207,977
	Accumulated depreciation	(2,379,033		)	(2,208,794		)
	Real estate owned, net	$	6,049,258		$	5,999,183
United Dominion Reality L.P. [Member]	'
Entity Information [Line Items]	'
Summary of carrying amounts for real estate owned (at cost)	'
	The following table summarizes the carrying amounts for our real estate owned (at cost) as of September 30, 2014 and December 31, 2013 (dollars in thousands):
		September 30,			December 31, 2013
		2014
	Land	$	998,797		$	1,004,447
	Depreciable property — held and used:
	Buildings, improvements, and furniture, fixture and equipment	3,100,598			3,103,970
	Under development:
	Land	9,447			9,447
	Buildings, improvements, and furniture, fixture and equipment	110,381			70,616
	Real estate owned	4,219,223			4,188,480
	Accumulated depreciation	(1,358,123		)	(1,241,574		)
	Real estate owned, net	$	2,861,100		$	2,946,906

Discontinued_Operations_Tables

Discontinued Operations (Tables)	9 Months Ended
	Sep. 30, 2014
Discontinued Operations and Disposal Groups [Abstract]	'
Summary of income from discontinued operations	'
	The following is a summary of income/(loss) from discontinued operations, net of tax for the three and nine months ended September 30, 2014 and 2013 (dollars in thousands):
		Three Months Ended September 30,					Nine Months Ended September 30,
		2014			2013		2014			2013
	Rental income	$	21		$	2,462	$	147		$	7,130
	Rental expenses	11			970		225			2,733
	Property management	1			68		4			196
	Real estate depreciation	—			528		—			1,608
	Other operating expenses	3			12		21			26
	Income/(loss) attributable to disposed properties and assets held for sale	6			884		(103		)	2,567
	Net gain/(loss) on the sale of depreciable properties	75			—		75			—
	Income tax benefit/(expense)	(2		)	—		38			—
	Income/(loss) from discontinued operations, net of tax	$	79		$	884	$	10		$	2,567
	Income/(loss) from discontinued operations attributable to UDR, Inc.	$	73		$	852	$	6		$	2,475

Discontinued_Operations_UNITED1

Discontinued Operations (UNITED DOMINION REALTY, L.P.) (Tables)	9 Months Ended
	Sep. 30, 2014
Entity Information [Line Items]	'
Summary of income from discontinued operations	'
	The following is a summary of income/(loss) from discontinued operations, net of tax for the three and nine months ended September 30, 2014 and 2013 (dollars in thousands):
		Three Months Ended September 30,					Nine Months Ended September 30,
		2014			2013		2014			2013
	Rental income	$	21		$	2,462	$	147		$	7,130
	Rental expenses	11			970		225			2,733
	Property management	1			68		4			196
	Real estate depreciation	—			528		—			1,608
	Other operating expenses	3			12		21			26
	Income/(loss) attributable to disposed properties and assets held for sale	6			884		(103		)	2,567
	Net gain/(loss) on the sale of depreciable properties	75			—		75			—
	Income tax benefit/(expense)	(2		)	—		38			—
	Income/(loss) from discontinued operations, net of tax	$	79		$	884	$	10		$	2,567
	Income/(loss) from discontinued operations attributable to UDR, Inc.	$	73		$	852	$	6		$	2,475
United Dominion Reality L.P. [Member]	'
Entity Information [Line Items]	'
Summary of income from discontinued operations	'
	The following is a summary of income/(loss) from discontinued operations for the three and nine months ended September 30, 2014 and 2013 (dollars in thousands):
		Three Months Ended September 30,					Nine Months Ended September 30,
		2014			2013		2014			2013
	Rental income	$	—		$	2,438	$	—		$	7,016
	Rental expenses	—			869		—			2,467
	Property management	—			67		—			193
	Real estate depreciation and amortization	—			524		—			1,590
	Income/(loss) from discontinued operations	$	—		$	978	$	—		$	2,766
	Income/(loss) from discontinued operations attributable to UDR, Inc.	$	—		$	978	$	—		$	2,766

Joint_Ventures_Tables

Joint Ventures (Tables)	9 Months Ended
	Sep. 30, 2014
Equity Method Investments and Joint Ventures [Abstract]	'
Combined Summary of Balance Sheets Relating to Unconsolidated Joint Ventures [Table Text Block]	'
	We evaluate our investments in unconsolidated joint ventures and partnerships when events or changes in circumstances indicate that there may be an other-than-temporary decline in value. We consid
Schedule of Equity Method Investments [Table Text Block]	'
	The following table summarizes the Company’s investment in and advances to unconsolidated joint ventures and partnerships, net, which are accounted for under the equity method of accounting as of September 30, 2014 and December 31, 2013 (dollars in thousands):
	Joint Venture		Location of Properties		Number of Properties		Number of Apartment Homes		Investment at						UDR’s Ownership Interest
					30-Sep-14		30-Sep-14		September 30, 2014			December 31, 2013			September 30, 2014				December 31, 2013
	Operating and development:
	UDR/MetLife I (a)		Various		0 operating communities		—		$	—		$	40,336		—			%	13.2			%
					5 land parcels		N/A		5,364			7,161			4			%	4			%
	UDR/MetLife II (a)		Various		21 operating communities		4,642		436,805			327,926			50			%	50			%
	UDR/MetLife Vitruvian Park®		Addison, TX		2 operating communities		739		79,807			79,318			50			%	50			%
					1 non-stabilized community		391
					6 land parcels		N/A
	UDR/KFH		Washington, D.C.		3 operating communities		660		22,891			25,919			30			%	30			%
	Texas		Texas		8 operating communities		3,359		(25,624		)	(23,591		)	20			%	20			%
	Other UDR/MetLife Development Joint Ventures		Various		2 development communities (b)		828		87,376			36,313			51			%	51			%
					1 land parcel		N/A
	Investment in and advances to unconsolidated joint ventures, net, before participating loan investment								606,619			493,382
			Location		Interest Rate		Years To Maturity		Investment at						Income From Participating Loan Investment For
									September 30, 2014			December 31, 2013			Three Months Ended September 30					Nine Months Ended September 30
																2014	2013			2014	2013
	Participating loan investment:
	Steele Creek		Denver, CO		6.50%		3.1		43,822			14,273				$642	—			$1,419	—
	Total investment in and advances to unconsolidated joint ventures, net								$	650,441		$	507,655
Financial information relating to unconsolidated joint ventures operations	'
	Combined summary financial information relating to all of the unconsolidated joint ventures’ and partnerships’ operations (not just our proportionate share), is presented below for the three and nine months ended September 30, 2014 and 2013 (dollars in thousands):
		Three Months Ended September 30,							Nine Months Ended September 30,
		2014				2013			2014			2013
	Total revenues	$	63,449			$	61,198		$	187,340		$	166,796
	Property operating expenses	(24,769		)		(24,509		)	(74,324		)	(64,532		)
	Real estate depreciation and amortization	(24,525		)		(21,285		)	(73,727		)	(58,699		)
	Operating income/(loss)	14,155				15,404			39,289			43,565
	Interest expense	(18,879		)		(19,370		)	(56,745		)	(53,282		)
	Other income/(expense)	—				—			(190		)	4
	Gain/(loss) on sale of real estate	(113		)		—			(25,492		)	—
	Income/(loss) from discontinued operations	—				(806		)	14			(22,592		)
	Net income/(loss)	$	(4,837	)		$	(4,772	)	$	(43,124	)	$	(32,305	)
	UDR income/(loss) from unconsolidated entities	$	(939	)		$	(3,794	)	$	(4,932	)	$	(6,081	)
Combined summary of balance sheets relating to unconsolidated joint ventures	'
	JOINT VENTURES AND PARTNERSHIPS
	UDR has entered into joint ventures and partnerships with unrelated third parties to acquire real estate assets that are either consolidated and included in Real estate owned on the Consolidated Balance Sheets or are accounted for under the equity method of accounting, and are included in Investment in and advances to unconsolidated joint ventures, net on the Consolidated Balance Sheets. The Company consolidates the entities that we control as well as any variable interest entity where we are the primary beneficiary. In addition, the Company consolidates any joint venture or partnership in which we are the general partner or managing member and the third party does not have the ability to substantively participate in the decision-making process nor the ability to remove us as general partner or managing member without cause.
	UDR’s joint ventures and partnerships are funded with a combination of debt and equity. Our losses are limited to our investment and except as noted below, the Company does not guarantee any debt, capital payout or other obligations associated with our joint ventures and partnerships.
	Consolidated Joint Ventures
	In December 2013, the Company consolidated its 95%/5% development joint ventures: 13th and Market JV in San Diego, CA and Domain College Park JV in Metropolitan D.C. The consolidation was due to the Company becoming the managing member of each of the joint ventures pursuant to amendments to the limited liability company agreement for each joint venture. In connection with the amendments, our partner received equity distributions reducing its capital account balances to zero, the Company replaced our partner as the managing member, and our partner no longer has the ability to substantively participate in the decision-making process, with only protective rights remaining. We accounted for the consolidations as asset acquisitions since the joint ventures were under development and not complete at the time of consolidation, resulting in no gain or loss upon consolidation and increasing our real estate owned by $129.4 million and our debt by $63.6 million. In addition pursuant to the amendments, the Company paid a non-refundable deposit to our partner in January 2014 of $2.0 million for each joint venture, or $4.0 million in total, for the right to exercise options in 2014 to acquire our partner’s upside participation in the joint ventures. The non-refundable deposits will be applied towards the future purchase price, which will be equivalent to our partner’s right to receive certain upside participation from the developments.
	Unconsolidated Joint Ventures and Partnerships
	The Company recognizes earnings or losses from our investments in unconsolidated joint ventures and partnerships consisting of our proportionate share of the net earnings or losses of the joint ventures and partnerships. In addition, we may earn fees for providing management services to the unconsolidated joint ventures and partnerships.
	The following table summarizes the Company’s investment in and advances to unconsolidated joint ventures and partnerships, net, which are accounted for under the equity method of accounting as of September 30, 2014 and December 31, 2013 (dollars in thousands):
	Joint Venture		Location of Properties		Number of Properties		Number of Apartment Homes		Investment at						UDR’s Ownership Interest
					30-Sep-14		30-Sep-14		September 30, 2014			December 31, 2013			September 30, 2014				December 31, 2013
	Operating and development:
	UDR/MetLife I (a)		Various		0 operating communities		—		$	—		$	40,336		—			%	13.2			%
					5 land parcels		N/A		5,364			7,161			4			%	4			%
	UDR/MetLife II (a)		Various		21 operating communities		4,642		436,805			327,926			50			%	50			%
	UDR/MetLife Vitruvian Park®		Addison, TX		2 operating communities		739		79,807			79,318			50			%	50			%
					1 non-stabilized community		391
					6 land parcels		N/A
	UDR/KFH		Washington, D.C.		3 operating communities		660		22,891			25,919			30			%	30			%
	Texas		Texas		8 operating communities		3,359		(25,624		)	(23,591		)	20			%	20			%
	Other UDR/MetLife Development Joint Ventures		Various		2 development communities (b)		828		87,376			36,313			51			%	51			%
					1 land parcel		N/A
	Investment in and advances to unconsolidated joint ventures, net, before participating loan investment								606,619			493,382
			Location		Interest Rate		Years To Maturity		Investment at						Income From Participating Loan Investment For
									September 30, 2014			December 31, 2013			Three Months Ended September 30					Nine Months Ended September 30
																2014	2013			2014	2013
	Participating loan investment:
	Steele Creek		Denver, CO		6.50%		3.1		43,822			14,273				$642	—			$1,419	—
	Total investment in and advances to unconsolidated joint ventures, net								$	650,441		$	507,655
	(a)	On March 31, 2014, the Company sold its minority ownership interests in two small operating communities located in Los Angeles, CA to MetLife for cash proceeds of $3.0 million, which resulted in an immaterial gain. On April 21, 2014, the Company increased its ownership interest in the remaining six operating communities in the UDR/MetLife I Joint Venture from 12% to 50%, and MetLife and the Company contributed these communities to the UDR/MetLife II Joint Venture. The Company paid MetLife $82.5 million for the additional ownership interests. The Company continues to manage the operating communities that were contributed to the UDR/MetLife II Joint Venture as well as the two operating communities in which it sold its minority ownership interests.
	In July 2014, the Company increased the ownership interest in two of these land sites to 50.1%. The remaining 49.9% continues to be held by our joint venture partner MetLife. The Company paid MetLife approximately $21.5 million for the additional ownership interests. As of September 30, 2014, the remaining assets in the UDR/MetLife I Joint Venture were comprised of five potential development land sites in which the Company has an average ownership interest of approximately 4%.
	(b)	The number of apartment homes for the communities under development presented in the table above is based on the projected number of total homes. As of September 30, 2014, no apartment homes had been completed in Other UDR/MetLife Development Joint Ventures.
	As of September 30, 2014 and December 31, 2013, the Company had deferred fees and deferred profit from the sale of properties to joint ventures or partnerships of $27.1 million and $25.4 million, respectively, which will be recognized through earnings over the weighted average life of the related properties, upon the disposition of the properties to a third party, or upon completion of certain development obligations.
	The Company recognized management fees for our management of the joint ventures and partnerships of $2.7 million and $8.3 million for the three and nine months ended September 30, 2014, respectively, and $2.8 million and $8.5 million during the three and nine months ended September 30, 2013, respectively, The management fees are included in Joint venture management and other fees on the Consolidated Statements of Operations.
	The Company may, in the future, make additional capital contributions to certain of our joint ventures and partnerships should additional capital contributions be necessary to fund acquisitions or operations.
	We evaluate our investments in unconsolidated joint ventures and partnerships when events or changes in circumstances indicate that there may be an other-than-temporary decline in value. We consider various factors to determine if a decrease in the value of the investment is other-than-temporary. The Company did not recognize any other-than-temporary decreases in the value of its investments in unconsolidated joint ventures or partnerships during the three and nine months ended September 30, 2014 and 2013.
	Combined summary balance sheets relating to all of the unconsolidated joint ventures and partnerships (not just our proportionate share) are presented below as of September 30, 2014 and December 31, 2013 (dollars in thousands):
		30-Sep-14				December 31, 2013
	Total real estate, net	$	3,012,380			$	3,124,178
	Cash and cash equivalents	40,656				41,792
	Other assets	37,903				32,234
	Total assets	$	3,090,939			$	3,198,204
	Amount due to UDR	$	10,856			$	12,187
	Third party debt	1,659,316				1,722,960
	Accounts payable and accrued liabilities	49,388				41,562
	Total liabilities	1,719,560				1,776,709
	Total equity	1,371,379				1,421,495
	Total liabilities and equity	$	3,090,939			$	3,198,204
	UDR’s investment in unconsolidated joint ventures	$	650,441			$	507,655
	Combined summary financial information relating to all of the unconsolidated joint ventures’ and partnerships’ operations (not just our proportionate share), is presented below for the three and nine months ended September 30, 2014 and 2013 (dollars in thousands):
		Three Months Ended September 30,							Nine Months Ended September 30,
		2014				2013			2014			2013
	Total revenues	$	63,449			$	61,198		$	187,340		$	166,796
	Property operating expenses	(24,769		)		(24,509		)	(74,324		)	(64,532		)
	Real estate depreciation and amortization	(24,525		)		(21,285		)	(73,727		)	(58,699		)
	Operating income/(loss)	14,155				15,404			39,289			43,565
	Interest expense	(18,879		)		(19,370		)	(56,745		)	(53,282		)
	Other income/(expense)	—				—			(190		)	4
	Gain/(loss) on sale of real estate	(113		)		—			(25,492		)	—
	Income/(loss) from discontinued operations	—				(806		)	14			(22,592		)
	Net income/(loss)	$	(4,837	)		$	(4,772	)	$	(43,124	)	$	(32,305	)
	UDR income/(loss) from unconsolidated entities	$	(939	)		$	(3,794	)	$	(4,932	)	$	(6,081	)

Secured_and_Unsecured_Debt_Tab

Secured and Unsecured Debt (Tables)	9 Months Ended
	Sep. 30, 2014
Debt Disclosure [Abstract]	'
Secured debt instruments	'
	The following is a summary of our secured and unsecured debt at September 30, 2014 and December 31, 2013 (dollars in thousands):
		Principal Outstanding						For the Nine Months Ended September 30, 2014
								Weighted Average			Weighted Average		Number of Communities
		September 30, 2014			December 31, 2013			Interest Rate			Years to Maturity		Encumbered
	Secured Debt:
	Fixed Rate Debt
	Mortgage notes payable (a)	$	438,172		$	445,706		5.47	%		1.8		8
	Fannie Mae credit facilities (b)	623,754			626,667			4.99	%		4.3		22
	Total fixed rate secured debt	1,061,926			1,072,373			5.19	%		3.2		30
	Variable Rate Debt
	Mortgage notes payable	31,337			63,595			1.94	%		2.3		1
	Tax-exempt secured notes payable (c)	94,700			94,700			0.77	%		8.4		2
	Fannie Mae credit facilities (b)	211,409			211,409			1.58	%		5.8		7
	Total variable rate secured debt	337,446			369,704			1.39	%		6.2		10
	Total Secured Debt	1,399,372			1,442,077			4.27	%		4		40
	Unsecured Debt:
	Commercial Banks
	Borrowings outstanding under an unsecured credit facility due December 2017 (d) (f)	160,000			—			1.1	%		3.2
	Senior Unsecured Notes
	3.70% Medium-Term Notes due October 2020 (net of discounts of $48 and $54, respectively) (f)	299,952			299,946			3.7	%		6
	4.63% Medium-Term Notes due January 2022 (net of discounts of $2,613 and $2,882, respectively) (f)	397,387			397,118			4.63	%		7.3
	3.75% Medium-Term Notes due July 2024 (net of discount of $1,017) (e) (f)	298,983			—			3.75	%		9.8
	1.30% Term Notes due June 2018 (f)	35,000			35,000			1.3	%		3.7
	1.53% Term Notes due June 2018 (f)	100,000			65,000			1.53	%		3.7
	5.13% Medium-Term Notes due January 2014	—			184,000			—	%		—
	5.50% Medium-Term Notes due April 2014 (net of discount of $20)	—			128,480			—	%		—
	5.25% Medium-Term Notes due January 2015 (net of discounts of $37 and $134, respectively)	325,138			325,041			5.25	%		0.3
	5.25% Medium-Term Notes due January 2016	83,260			83,260			5.25	%		1.3
	2.17% Term Notes due June 2018 (f)	215,000			250,000			2.17	%		3.7
	8.50% Debentures due September 2024	15,644			15,644			8.5	%		10
	4.25% Medium-Term Notes due June 2018 (net of discounts of $1,572 and $1,893, respectively) (f)	298,428			298,107			4.25	%		3.7
	Other	28			30			N/A			N/A
	Total Unsecured Debt	2,228,820			2,081,626			3.8	%		4.9
	Total Debt	$	3,628,192		$	3,523,703		3.98	%		4.5
Secured credit facilities	'
	Further information related to these credit facilities is as follows (dollars in thousands):
		September 30, 2014			December 31, 2013
	Borrowings outstanding	$	835,163		$	838,076
	Weighted average borrowings during the period ended	836,305			839,597
	Maximum daily borrowings during the period ended	837,564			841,494
	Weighted average interest rate during the period ended	4.1		%	4.2		%
	Weighted average interest rate at the end of the period	4.1		%	4.1		%
Summary of short-term bank borrowings under bank credit facility	'
	The following is a summary of short-term bank borrowings under UDR’s bank credit facility at September 30, 2014 and December 31, 2013 (dollars in thousands):
		September 30, 2014			December 31, 2013
	Total revolving credit facility	$	900,000		$	900,000
	Borrowings outstanding at end of period (1)	160,000			—
	Weighted average daily borrowings during the period ended	321,821			169,844
	Maximum daily borrowings during the period ended	625,000			372,000
	Weighted average interest rate during the period ended	1.2		%	1.2		%
	Interest rate at end of the period	1.1		%	1.3		%
	(1) Excludes $2.2 million of letters of credit at September 30, 2014 and December 31, 2013.
	(e) On June 26, 2014, the Company issued $300 million of 3.750% senior unsecured medium-term notes due July 1, 2024. Interest is payable semi-annually beginning on January 1, 2015. The notes were priced at 99.652% of the principal amount at issuance and had a discount of $1.0 million at September 30, 2014. The Company used the net proceeds to pay down borrowings outstanding on our $900 million unsecured credit facility and for general corporate purposes. The notes are fully and unconditionally guaranteed by the Operating Partnership.
	(f) The Operating Partnership is a guarantor at September 30, 2014 and December 31, 2013.
Schedule of Maturities of Long-term Debt [Table Text Block]	'
	The aggregate maturities, including amortizing principal payments of unsecured and secured debt, of total debt for the next five calendar years subsequent to September 30, 2014 are as follows (dollars in thousands):
	Year		Total Fixed Secured Debt			Total Variable Secured Debt			Total Secured Debt			Total Unsecured Debt (a)		Total Debt
	2014		$	37,835		$	—		$	37,835		$	—	$	37,835
	2015		197,359			—			197,359			323,874		521,233
	2016		136,434			31,337			167,771			82,417		250,188
	2017		177,955			65,000			242,955			160,000		402,955
	2018		176,472			50,000			226,472			648,510		874,982
	Thereafter		335,871			191,109			526,980			1,014,019		1,540,999
	Total		$	1,061,926		$	337,446		$	1,399,372		$	2,228,820	$	3,628,192
	(a) With the exception of the 1.30% Term Notes due June 2018 and the revolving credit facility which carry a variable interest rate, all unsecured debt carries fixed interest rates.

Debt_UNITED_DOMINION_REALTY_LP1

Debt (UNITED DOMINION REALTY, L.P.) (Tables)	9 Months Ended
	Sep. 30, 2014
Entity Information [Line Items]	'
Secured debt instruments	'
	The following is a summary of our secured and unsecured debt at September 30, 2014 and December 31, 2013 (dollars in thousands):
		Principal Outstanding						For the Nine Months Ended September 30, 2014
								Weighted Average			Weighted Average		Number of Communities
		September 30, 2014			December 31, 2013			Interest Rate			Years to Maturity		Encumbered
	Secured Debt:
	Fixed Rate Debt
	Mortgage notes payable (a)	$	438,172		$	445,706		5.47	%		1.8		8
	Fannie Mae credit facilities (b)	623,754			626,667			4.99	%		4.3		22
	Total fixed rate secured debt	1,061,926			1,072,373			5.19	%		3.2		30
	Variable Rate Debt
	Mortgage notes payable	31,337			63,595			1.94	%		2.3		1
	Tax-exempt secured notes payable (c)	94,700			94,700			0.77	%		8.4		2
	Fannie Mae credit facilities (b)	211,409			211,409			1.58	%		5.8		7
	Total variable rate secured debt	337,446			369,704			1.39	%		6.2		10
	Total Secured Debt	1,399,372			1,442,077			4.27	%		4		40
	Unsecured Debt:
	Commercial Banks
	Borrowings outstanding under an unsecured credit facility due December 2017 (d) (f)	160,000			—			1.1	%		3.2
	Senior Unsecured Notes
	3.70% Medium-Term Notes due October 2020 (net of discounts of $48 and $54, respectively) (f)	299,952			299,946			3.7	%		6
	4.63% Medium-Term Notes due January 2022 (net of discounts of $2,613 and $2,882, respectively) (f)	397,387			397,118			4.63	%		7.3
	3.75% Medium-Term Notes due July 2024 (net of discount of $1,017) (e) (f)	298,983			—			3.75	%		9.8
	1.30% Term Notes due June 2018 (f)	35,000			35,000			1.3	%		3.7
	1.53% Term Notes due June 2018 (f)	100,000			65,000			1.53	%		3.7
	5.13% Medium-Term Notes due January 2014	—			184,000			—	%		—
	5.50% Medium-Term Notes due April 2014 (net of discount of $20)	—			128,480			—	%		—
	5.25% Medium-Term Notes due January 2015 (net of discounts of $37 and $134, respectively)	325,138			325,041			5.25	%		0.3
	5.25% Medium-Term Notes due January 2016	83,260			83,260			5.25	%		1.3
	2.17% Term Notes due June 2018 (f)	215,000			250,000			2.17	%		3.7
	8.50% Debentures due September 2024	15,644			15,644			8.5	%		10
	4.25% Medium-Term Notes due June 2018 (net of discounts of $1,572 and $1,893, respectively) (f)	298,428			298,107			4.25	%		3.7
	Other	28			30			N/A			N/A
	Total Unsecured Debt	2,228,820			2,081,626			3.8	%		4.9
	Total Debt	$	3,628,192		$	3,523,703		3.98	%		4.5
Secured credit facilities	'
	Further information related to these credit facilities is as follows (dollars in thousands):
		September 30, 2014			December 31, 2013
	Borrowings outstanding	$	835,163		$	838,076
	Weighted average borrowings during the period ended	836,305			839,597
	Maximum daily borrowings during the period ended	837,564			841,494
	Weighted average interest rate during the period ended	4.1		%	4.2		%
	Weighted average interest rate at the end of the period	4.1		%	4.1		%
Aggregate maturities of secured debt	'
	The aggregate maturities, including amortizing principal payments of unsecured and secured debt, of total debt for the next five calendar years subsequent to September 30, 2014 are as follows (dollars in thousands):
	Year		Total Fixed Secured Debt			Total Variable Secured Debt			Total Secured Debt			Total Unsecured Debt (a)		Total Debt
	2014		$	37,835		$	—		$	37,835		$	—	$	37,835
	2015		197,359			—			197,359			323,874		521,233
	2016		136,434			31,337			167,771			82,417		250,188
	2017		177,955			65,000			242,955			160,000		402,955
	2018		176,472			50,000			226,472			648,510		874,982
	Thereafter		335,871			191,109			526,980			1,014,019		1,540,999
	Total		$	1,061,926		$	337,446		$	1,399,372		$	2,228,820	$	3,628,192
	(a) With the exception of the 1.30% Term Notes due June 2018 and the revolving credit facility which carry a variable interest rate, all unsecured debt carries fixed interest rates.
United Dominion Reality L.P. [Member]	'
Entity Information [Line Items]	'
Secured debt instruments	'
	Secured debt consists of the following as of September 30, 2014 and December 31, 2013 (dollars in thousands):
		Principal Outstanding						For the Nine Months Ended September 30, 2014
		September 30,			December 31, 2013			Weighted Average			Weighted Average		Number of Communities
		2014						Interest Rate			Years to Maturity		Encumbered
	Fixed Rate Debt
	Mortgage notes payable	$	380,506		$	386,803		5.46	%		1.8		5
	Fannie Mae credit facilities	378,709			379,003			4.71	%		4.7		10
	Total fixed rate secured debt	759,215			765,806			5.09	%		3.3		15
	Variable Rate Debt
	Tax-exempt secured note payable	27,000			27,000			0.74	%		17.5		1
	Fannie Mae credit facilities	142,058			142,059			1.88	%		7		5
	Total variable rate secured debt	169,058			169,059			1.7	%		8.7		6
	Total Secured Debt	$	928,273		$	934,865		4.47	%		4.3		21
Secured credit facilities	'
	ollowing information relates to the credit facilities allocated to the Operating Partnership (dollars in thousands):
		September 30,			December 31, 2013
		2014
	Borrowings outstanding	$	520,768		$	521,062
	Weighted average borrowings during the period ended	521,480			522,007
	Maximum daily borrowings during the period	522,265			523,187
	Weighted average interest rate during the period ended	3.9		%	4.2		%
	Interest rate at the end of the period	3.9		%	4.1		%
Aggregate maturities of secured debt	'
	The aggregate maturities of the Operating Partnership’s secured debt due during each of the next five calendar years subsequent to September 30, 2014 are as follows (dollars in thousands):
			Fixed						Variable
	Year		Mortgage			Credit			Tax Exempt			Credit		Total
			Notes			Facilities			Notes Payable			Facilities
	2014		$	2,134		$	89		$	—		$	—	$	2,223
	2015		193,075			366			—			—		193,441
	2016		131,946			385			—			—		132,331
	2017		1,630			15,640			—			6,566		23,836
	2018		1,685			161,754			—			46,272		209,711
	Thereafter		50,036			200,475			27,000			89,220		366,731
	Total		$	380,506		$	378,709		$	27,000		$	142,058	$	928,273

IncomeLoss_Per_Share_Tables

Income/(Loss) Per Share (Tables)	9 Months Ended
	Sep. 30, 2014
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]	'
Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block]	'
	The following table sets forth the additional shares of common stock outstanding by equity instrument if converted to common stock for each of the three and nine months ended September 30, 2014 and 2013 (shares in thousands):
			Three Months Ended September 30,					Nine Months Ended September 30,
			2014		2013			2014			2013
	OP Units		9,189		9,323			9,274			9,343
	Preferred stock		3,036		3,036			3,036			3,036
	Stock options and unvested restricted stock		2,077		1,469			1,974			1,477
(Loss)/earnings per share	'
	The following table sets forth the computation of basic and diluted income/(loss) per share for the periods presented (dollars and shares in thousands, except per share data):
		Three Months Ended September 30,							Nine Months Ended September 30,
		2014			2013				2014			2013
	Numerator for income/(loss) per share:
	Income/(loss) from continuing operations	$	10,611		$	2,351			$	9,775		$	5,713
	Gain/(loss) on sale of real estate owned, net of tax	31,302			—				82,305			—
	(Income)/loss from continuing operations attributable to redeemable noncontrolling interests in the Operating Partnership	(1,441		)	(52		)		(3,167		)	(106		)
	(Income)/loss from continuing operations attributable to noncontrolling interests	4			37				(2		)	30
	Income/(loss) from continuing operations attributable to UDR, Inc.	40,476			2,336				88,911			5,637
	Distributions to preferred stockholders - Series E (Convertible)	(931		)	(931		)		(2,793		)	(2,793		)
	Income/(loss) from continuing operations attributable to common stockholders	$	39,545		$	1,405			$	86,118		$	2,844
	Income/(loss) from discontinued operations, net of tax	$	79		$	884			$	10		$	2,567
	(Income)/loss from discontinued operations attributable to redeemable noncontrolling interests in the Operating Partnership	(6		)	(32		)		(4		)	(92		)
	Income/(loss) from discontinued operations attributable to common stockholders	$	73		$	852			$	6		$	2,475
	Net income/(loss) attributable to common stockholders	$	39,618		$	2,257			$	86,124		$	5,319
	Denominator for income/(loss) per share:
	Weighted average common shares outstanding	252,891			250,744				251,860			250,663
	Non-vested restricted stock awards	(1,236		)	(759		)		(1,159		)	(701		)
	Denominator for basic income/(loss) per share	251,655			249,985				250,701			249,962
	Incremental shares issuable from assumed conversion of stock options and unvested restricted stock	2,077			1,469				1,974			1,477
	Denominator for diluted income/(loss) per share	253,732			251,454				252,675			251,439
	Income/(loss) per weighted average common share-basic:
	Income/(loss) from continuing operations attributable to common stockholders	$	0.16		$	0.01			$	0.34		$	0.01
	Income/(loss) from discontinued operations attributable to common stockholders	0			0				0			0.01
	Net income/(loss) attributable to common stockholders	$	0.16		$	0.01			$	0.34		$	0.02
	Income/(loss) per weighted average common share-diluted:
	Income/(loss) from continuing operations attributable to common stockholders	$	0.16		$	0.01			$	0.34		$	0.01
	Income/(loss) from discontinued operations attributable to common stockholders	0			0				0			0.01
	Net income/(loss) attributable to common stockholders	$	0.16		$	0.01			$	0.34		$	0.02

IncomeLoss_Per_Operating_Partn1

Income/(Loss) Per Operating Partnership Unit (UNITED DOMINION REALTY, L.P.) Income/(Loss) Per Operating Partnership Unit (Tables)	9 Months Ended
	Sep. 30, 2014
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]	'
Earnings/(loss) per operating partnership unit	'
	The following table sets forth the computation of basic and diluted income/(loss) per share for the periods presented (dollars and shares in thousands, except per share data):
		Three Months Ended September 30,								Nine Months Ended September 30,
		2014				2013				2014				2013
	Numerator for income/(loss) per share:
	Income/(loss) from continuing operations	$	10,611			$	2,351			$	9,775			$	5,713
	Gain/(loss) on sale of real estate owned, net of tax	31,302				—				82,305				—
	(Income)/loss from continuing operations attributable to redeemable noncontrolling interests in the Operating Partnership	(1,441		)		(52		)		(3,167		)		(106		)
	(Income)/loss from continuing operations attributable to noncontrolling interests	4				37				(2		)		30
	Income/(loss) from continuing operations attributable to UDR, Inc.	40,476				2,336				88,911				5,637
	Distributions to preferred stockholders - Series E (Convertible)	(931		)		(931		)		(2,793		)		(2,793		)
	Income/(loss) from continuing operations attributable to common stockholders	$	39,545			$	1,405			$	86,118			$	2,844
	Income/(loss) from discontinued operations, net of tax	$	79			$	884			$	10			$	2,567
	(Income)/loss from discontinued operations attributable to redeemable noncontrolling interests in the Operating Partnership	(6		)		(32		)		(4		)		(92		)
	Income/(loss) from discontinued operations attributable to common stockholders	$	73			$	852			$	6			$	2,475
	Net income/(loss) attributable to common stockholders	$	39,618			$	2,257			$	86,124			$	5,319
	Denominator for income/(loss) per share:
	Weighted average common shares outstanding	252,891				250,744				251,860				250,663
	Non-vested restricted stock awards	(1,236		)		(759		)		(1,159		)		(701		)
	Denominator for basic income/(loss) per share	251,655				249,985				250,701				249,962
	Incremental shares issuable from assumed conversion of stock options and unvested restricted stock	2,077				1,469				1,974				1,477
	Denominator for diluted income/(loss) per share	253,732				251,454				252,675				251,439
	Income/(loss) per weighted average common share-basic:
	Income/(loss) from continuing operations attributable to common stockholders	$	0.16			$	0.01			$	0.34			$	0.01
	Income/(loss) from discontinued operations attributable to common stockholders	0				0				0				0.01
	Net income/(loss) attributable to common stockholders	$	0.16			$	0.01			$	0.34			$	0.02
	Income/(loss) per weighted average common share-diluted:
	Income/(loss) from continuing operations attributable to common stockholders	$	0.16			$	0.01			$	0.34			$	0.01
	Income/(loss) from discontinued operations attributable to common stockholders	0				0				0				0.01
	Net income/(loss) attributable to common stockholders	$	0.16			$	0.01			$	0.34			$	0.02
United Dominion Reality L.P. [Member]	'
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]	'
Earnings/(loss) per operating partnership unit	'
	The following table sets forth the computation of basic and diluted income/(loss) per OP Unit for the periods presented (dollars in thousands, except per OP Unit data):
			Three Months Ended September 30,								Nine Months Ended September 30,
			2014				2013				2014				2013
	Numerator for income/(loss) per OP Unit — basic and diluted:
	Income/(loss) from continuing operations		$	8,875			$	10,072			$	23,606			$	26,278
	Gain/(loss) on sale of real estate owned		—				—				40,687				—
	(Income)/loss from continuing operations attributable to noncontrolling interests		(238		)		(39		)		(697		)		(151		)
	Income/(loss) from continuing operations attributable to OP unitholders		$	8,637			$	10,033			$	63,596			$	26,127
	Income/(loss) from discontinued operations		$	—			$	978			$	—			$	2,766
	(Income)/loss from discontinued operations attributable to noncontrolling interests		—				—				—				—
	Income/(loss) from discontinued operations attributable to OP unitholders		$	—			$	978			$	—			$	2,766
	Net income/(loss)		$	8,875			$	11,050			$	64,293			$	29,044
	Net (income)/loss attributable to noncontrolling interests		(238		)		(39		)		(697		)		(151		)
	Net income/(loss) attributable to OP unitholders		$	8,637			$	11,011			$	63,596			$	28,893
	Denominator for income/(loss) per OP Unit — basic and diluted:
	Weighted average OP Units outstanding — basic and diluted		183,279				184,281				183,279				184,281
	Income/(loss) per weighted average OP Unit — basic and diluted:
	Income/(loss) from continuing operations attributable to OP unitholders		$	0.05			0.05				$	0.35			$	0.14
	Income/(loss) from discontinued operations attributable to OP unitholders		$	—			$	0.01			$	—			$	0.02
	Net income/(loss) attributable to OP unitholders		$	0.05			0.06				$	0.35			$	0.16

Noncontrolling_Interests_Table

Noncontrolling Interests (Tables)	9 Months Ended
	Sep. 30, 2014
Noncontrolling Interest [Abstract]	'
Redeemable noncontrolling interests in the Operating Partnership	'
	The following table sets forth redeemable noncontrolling interests in the Operating Partnership for the following period (dollars in thousands):
	Redeemable noncontrolling interests in the Operating Partnership, December 31, 2013	$	217,597
	Mark-to-market adjustment to redeemable noncontrolling interests in the Operating Partnership	40,771
	Conversion of OP Units to Common Stock	(4,318		)
	Net income/(loss) attributable to redeemable noncontrolling interests in the Operating Partnership	3,171
	Distributions to redeemable noncontrolling interests in the Operating Partnership	(7,570		)
	Allocation of other comprehensive income/(loss)	163
	Redeemable noncontrolling interests in the Operating Partnership, September 30, 2014	$	249,814
	The following sets forth net income/(loss) attributable to common stockholders and transfers from redeemable noncontrolling interests in the Operating Partnership for the following periods (dollars in thousands):
			Three Months Ended September 30,				Nine Months Ended September 30,
			2014		2013		2014		2013
	Net income/(loss) attributable to common stockholders		$	39,618	$	2,257	$	86,124	$	5,319
	Conversion of OP Units to UDR Common stock		4,127		—		4,318		1,711
	Change in equity from net income/(loss) attributable to common stockholders and conversion of OP Units to UDR Common Stock		$	43,745	$	2,257	$	90,442	$	7,030

Fair_Value_of_Derivatives_and_2

Fair Value of Derivatives and Financial Instruments (Tables)	9 Months Ended
	Sep. 30, 2014
Fair Value Disclosures [Abstract]	'
Estimated fair values	'
	The estimated fair values of the Company’s financial instruments either recorded or disclosed on a recurring basis as of September 30, 2014 and December 31, 2013 are summarized as follows (dollars in thousands):
						Fair Value at September 30, 2014, Using
		Total Carrying Amount in Statement of Financial Position at September 30, 2014		Fair Value Estimate at September 30, 2014		Quoted Prices in		Significant		Significant
						Active Markets		Other		Unobservable
						for Identical		Observable		Inputs
						Assets or		Inputs		(Level 3)
						Liabilities		(Level 2)
						(Level 1)
	Description:
	Notes receivable (a)	$	18,318	$	18,858	$	—	$	—	$	18,858
	Derivatives- Interest rate contracts (b)	299		299		—		299		—
	Total assets	$	18,617	$	19,157	$	—	$	299	$	18,858
	Derivatives- Interest rate contracts (b)	$	2,382	$	2,382	$	—	$	2,382	$	—
	Secured debt instruments- fixed rate: (c)
	Mortgage notes payable	438,172		451,582		—		—		451,582
	Fannie Mae credit facilities	623,754		655,035		—		—		655,035
	Secured debt instruments- variable rate: (c)
	Mortgage notes payable	31,337		31,337		—		—		31,337
	Tax-exempt secured notes payable	94,700		94,700		—		—		94,700
	Fannie Mae credit facilities	211,409		211,409		—		—		211,409
	Unsecured debt instruments: (c)
	Commercial bank	160,000		160,000		—		—		160,000
	Senior unsecured notes	2,068,820		2,136,468		—		—		2,136,468
	Total liabilities	$	3,630,574	$	3,742,913	$	—	$	2,382	$	3,740,531
	Redeemable noncontrolling interests in the Operating Partnership (d)	$	249,814	$	249,814	$	—	$	249,814	$	—
						Fair Value at December 31, 2013, Using
		Total Carrying Amount in Statement of Financial Position at December 31, 2013		Fair Value Estimate at December 31, 2013		Quoted Prices in		Significant		Significant
						Active Markets		Other		Unobservable
						for Identical		Observable		Inputs
						Assets or		Inputs		(Level 3)
						Liabilities		(Level 2)
						(Level 1)
	Description:
	Notes receivable (a)	$	83,033	$	83,833	$	—	$	—	$	83,833
	Total assets	$	83,033	$	83,833	$	—	$	—	$	83,833
	Derivatives- Interest rate contracts (b)	$	4,965	$	4,965	$	—	$	4,965	$	—
	Secured debt instruments- fixed rate: (c)
	Mortgage notes payable	445,706		466,375		—		—		466,375
	Fannie Mae credit facilities	626,667		661,094		—		—		661,094
	Secured debt instruments- variable rate: (c)
	Mortgage notes payable	63,595		63,595		—		—		63,595
	Tax-exempt secured notes payable	94,700		94,700		—		—		94,700
	Fannie Mae credit facilities	211,409		211,409		—		—		211,409
	Unsecured debt instruments: (c)
	Senior unsecured notes	2,081,626		2,149,003		—		—		2,149,003
	Total liabilities	$	3,528,668	$	3,651,141	$	—	$	4,965	$	3,646,176
	Redeemable noncontrolling interests in the Operating Partnership (d)	$	217,597	$	217,597	$	—	$	217,597	$	—
	(a)	See Note 2, Significant Accounting Policies.
	(b)	See Note 10, Derivatives and Hedging Activity.
	(c)	See Note 6, Secured and Unsecured Debt.
	(d)	See Note 8, Noncontrolling Interests

Fair_Value_of_Derivatives_and_3

Fair Value of Derivatives and Financial Instruments (UNITED DOMINION REALTY, L.P.) (Tables)	9 Months Ended
	Sep. 30, 2014
Entity Information [Line Items]	'
Estimated fair values	'
	The estimated fair values of the Company’s financial instruments either recorded or disclosed on a recurring basis as of September 30, 2014 and December 31, 2013 are summarized as follows (dollars in thousands):
						Fair Value at September 30, 2014, Using
		Total Carrying Amount in Statement of Financial Position at September 30, 2014		Fair Value Estimate at September 30, 2014		Quoted Prices in		Significant		Significant
						Active Markets		Other		Unobservable
						for Identical		Observable		Inputs
						Assets or		Inputs		(Level 3)
						Liabilities		(Level 2)
						(Level 1)
	Description:
	Notes receivable (a)	$	18,318	$	18,858	$	—	$	—	$	18,858
	Derivatives- Interest rate contracts (b)	299		299		—		299		—
	Total assets	$	18,617	$	19,157	$	—	$	299	$	18,858
	Derivatives- Interest rate contracts (b)	$	2,382	$	2,382	$	—	$	2,382	$	—
	Secured debt instruments- fixed rate: (c)
	Mortgage notes payable	438,172		451,582		—		—		451,582
	Fannie Mae credit facilities	623,754		655,035		—		—		655,035
	Secured debt instruments- variable rate: (c)
	Mortgage notes payable	31,337		31,337		—		—		31,337
	Tax-exempt secured notes payable	94,700		94,700		—		—		94,700
	Fannie Mae credit facilities	211,409		211,409		—		—		211,409
	Unsecured debt instruments: (c)
	Commercial bank	160,000		160,000		—		—		160,000
	Senior unsecured notes	2,068,820		2,136,468		—		—		2,136,468
	Total liabilities	$	3,630,574	$	3,742,913	$	—	$	2,382	$	3,740,531
	Redeemable noncontrolling interests in the Operating Partnership (d)	$	249,814	$	249,814	$	—	$	249,814	$	—
						Fair Value at December 31, 2013, Using
		Total Carrying Amount in Statement of Financial Position at December 31, 2013		Fair Value Estimate at December 31, 2013		Quoted Prices in		Significant		Significant
						Active Markets		Other		Unobservable
						for Identical		Observable		Inputs
						Assets or		Inputs		(Level 3)
						Liabilities		(Level 2)
						(Level 1)
	Description:
	Notes receivable (a)	$	83,033	$	83,833	$	—	$	—	$	83,833
	Total assets	$	83,033	$	83,833	$	—	$	—	$	83,833
	Derivatives- Interest rate contracts (b)	$	4,965	$	4,965	$	—	$	4,965	$	—
	Secured debt instruments- fixed rate: (c)
	Mortgage notes payable	445,706		466,375		—		—		466,375
	Fannie Mae credit facilities	626,667		661,094		—		—		661,094
	Secured debt instruments- variable rate: (c)
	Mortgage notes payable	63,595		63,595		—		—		63,595
	Tax-exempt secured notes payable	94,700		94,700		—		—		94,700
	Fannie Mae credit facilities	211,409		211,409		—		—		211,409
	Unsecured debt instruments: (c)
	Senior unsecured notes	2,081,626		2,149,003		—		—		2,149,003
	Total liabilities	$	3,528,668	$	3,651,141	$	—	$	4,965	$	3,646,176
	Redeemable noncontrolling interests in the Operating Partnership (d)	$	217,597	$	217,597	$	—	$	217,597	$	—
	(a)	See Note 2, Significant Accounting Policies.
	(b)	See Note 10, Derivatives and Hedging Activity.
	(c)	See Note 6, Secured and Unsecured Debt.
	(d)	See Note 8, Noncontrolling Interests
United Dominion Reality L.P. [Member]	'
Entity Information [Line Items]	'
Estimated fair values	'
	The estimated fair values of the Operating Partnership’s financial instruments either recorded or disclosed on a recurring basis as of September 30, 2014 and December 31, 2013 are summarized as follows (dollars in thousands):
						Fair Value at September 30, 2014, Using
		Total Carrying Amount in Statement of Financial Position on September 30, 2014		Fair Value Estimate at September 30, 2014		Quoted Prices in		Significant Other		Significant
						Active Markets		Observable		Unobservable
						for Identical		Inputs		Inputs
						Assets or		(Level 2)		(Level 3)
						Liabilities
						(Level 1)
	Description:
	Derivatives- Interest rate contracts (a)	$	5	$	5	$	—	$	5	$	—
	Total assets	$	5	$	5	$	—	$	5	$	—
	Derivatives- Interest rate contracts (a)	$	1,324	$	1,324	$	—	$	1,324	$	—
	Secured debt instruments- fixed rate: (b)
	Mortgage notes payable	380,506		392,883		—		—		392,883
	Fannie Mae credit facilities	378,709		394,849		—		—		394,849
	Secured debt instruments- variable rate: (b)
	Tax-exempt secured notes payable	27,000		27,000		—		—		27,000
	Fannie Mae credit facilities	142,059		142,059		—		—		142,059
	Total liabilities	$	929,598	$	958,115	$	—	$	1,324	$	956,791
						Fair Value at December 31, 2013, Using
		Total Carrying Amount in Statement of Financial Position on December 31, 2013		Fair Value Estimate at December 31, 2013		Quoted Prices in		Significant Other		Significant
						Active Markets		Observable		Unobservable
						for Identical		Inputs		Inputs
						Assets or		(Level 2)		(Level 3)
						Liabilities
						(Level 1)
	Description:
	Derivatives- Interest rate contracts (a)	$	2,731	$	2,731	$	—	$	2,731	$	—
	Secured debt instruments- fixed rate: (b)
	Mortgage notes payable	386,803		403,695		—		—		403,695
	Fannie Mae credit facilities	379,003		394,239		—		—		394,239
	Secured debt instruments- variable rate: (b)
	Tax-exempt secured notes payable	27,000		27,000		—		—		27,000
	Fannie Mae credit facilities	142,059		142,059		—		—		142,059
	Total liabilities	$	937,596	$	969,724	$	—	$	2,731	$	966,993
	(a)	See Note 8, Derivatives and Hedging Activity.
	(b)	See Note 5, Debt

Derivatives_and_Hedging_Activi2

Derivatives and Hedging Activity (Tables)	9 Months Ended
	Sep. 30, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]	'
Outstanding interest rate derivatives	'
	As of September 30, 2014, the Company had the following outstanding interest rate derivatives that were designated as cash flow hedges of interest rate risk (dollars in thousands):
	Interest Rate Derivative		Number of Instruments		Notional
	Interest rate swaps		14		$	419,787
	Interest rate caps		6		$	339,488
	Derivatives not designated as hedges are not speculative and are used to manage the Company’s exposure to interest rate movements and other identified risks but do not meet the strict hedge accounting requirements of GAAP. Changes in the fair value of derivatives not designated in hedging relationships are recorded directly in earnings and resulted in no adjustment to earnings for the three and nine months ended September 30, 2014 and a gain/(loss) of $280,000 and $275,000 for the three and nine months ended September 30, 2013, respectively.
	As of September 30, 2014, the Company did not have any outstanding derivatives that were not designated as hedges in qualifying hedging relationships.
Fair value of Company's derivative financial instruments and their classification on Consolidated Balance Sheet	'
	The tables below present the fair value of the Company’s derivative financial instruments as well as their classification on the Consolidated Balance Sheets as of September 30, 2014 and December 31, 2013 (dollars in thousands):
		Asset Derivatives										Liability Derivatives
				Fair Value at:										Fair Value at:
		Balance		September 30,				December 31,				Balance		September 30,				December 31,
		Sheet Location		2014				2013				Sheet Location		2014				2013
	Derivatives designated as hedging instruments:
	Interest rate products	Other assets		$	299			—				Other liabilities		$	2,382			4,965
	Derivatives not designated as hedging instruments:
	Interest rate products	Other assets		$	—			$	—			Other liabilities		$	—			$	—
Effect of Company's derivative financial instruments on Consolidated Statements of Operation	'
	The tables below present the effect of the Company’s derivative financial instruments on the Consolidated Statements of Operations for the three and nine months ended September 30, 2014 and 2013 (dollars in thousands):
			Amount of Gain or (Loss) Recognized in OCI on Derivative (Effective Portion)								Location of Gain or (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)		Amount of Gain or (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)								Location of Gain or (Loss) Recognized in Income on Derivative (Ineffective Portion and Amount Excluded from Effectiveness Testing)	Amount of Gain or (Loss) Recognized in Income on Derivative (Ineffective Portion and Amount Excluded from Effectiveness Testing)
	Derivatives in Cash Flow Hedging Relationships		2014				2013						2014				2013					2014		2013
	For the Three Months Ended September 30,
	Interest rate products		$	362			$	(386	)		Interest expense		$	(1,130	)		$	(1,635	)		Interest expense	$	—	$	—
	For the Nine Months Ended September 30,
	Interest rate products		$	611			$	(334	)		Interest expense		$	(3,809	)		$	(5,180	)		Interest expense	$	3	$	—
Effect of Company's derivatives not designated as hedging instruments on the Consolidated Statements of Operations	'
	Derivatives Not Designated as Hedging Instruments		Location of Gain or (Loss) Recognized in Income on Derivative		Amount of Gain or (Loss) Recognized in Income on Derivative
					2014				2013
	For the Three Months Ended September 30,
	Interest rate products		Interest and other income/(loss), net		$	—			$	280
	For the Nine Months Ended September 30,
	Interest rate products		Interest and other income/(loss), net		$	—			$	275
Offsetting Assets [Table Text Block]	'
	Offsetting of Derivative Assets
															Gross Amounts Not Offset in the Consolidated Balance Sheets
			Gross Amounts of Recognized Assets				Gross Amounts Offset in the Consolidated Balance Sheets				Net Amounts of Assets Presented in the Consolidated Balance Sheets (a)				Financial Instruments				Cash Collateral Received			Net Amount
	September 30, 2014		$	299			$	—			$	299			$	(253	)		$	—		$	46
	December 31, 2013		$	—			$	—			$	—			$	—			$	—		$	—
	(a) 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.
Offsetting Liabilities [Table Text Block]	'
	Offsetting of Derivative Liabilities
															Gross Amounts Not Offset in the Consolidated Balance Sheets
			Gross Amounts of Recognized Liabilities				Gross Amounts Offset in the Consolidated Balance Sheets				Net Amounts of Liabilities Presented in the Consolidated Balance Sheets (b)				Financial Instruments				Cash Collateral Posted			Net Amount
	September 30, 2014		$	2,382			$	—			$	2,382			$	(253	)		$	—		$	2,129
	December 31, 2013		$	4,965			$	—			$	4,965			$	—			$	—		$	4,965
	(b) 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.

Derivatives_and_Hedging_Activi3

Derivatives and Hedging Activity (UNITED DOMINION REALTY, L.P.) (Tables)	9 Months Ended
	Sep. 30, 2014
Entity Information [Line Items]	'
Outstanding interest rate derivatives	'
	As of September 30, 2014, the Company had the following outstanding interest rate derivatives that were designated as cash flow hedges of interest rate risk (dollars in thousands):
	Interest Rate Derivative		Number of Instruments		Notional
	Interest rate swaps		14		$	419,787
	Interest rate caps		6		$	339,488
	Derivatives not designated as hedges are not speculative and are used to manage the Company’s exposure to interest rate movements and other identified risks but do not meet the strict hedge accounting requirements of GAAP. Changes in the fair value of derivatives not designated in hedging relationships are recorded directly in earnings and resulted in no adjustment to earnings for the three and nine months ended September 30, 2014 and a gain/(loss) of $280,000 and $275,000 for the three and nine months ended September 30, 2013, respectively.
	As of September 30, 2014, the Company did not have any outstanding derivatives that were not designated as hedges in qualifying hedging relationships.
Fair value of Company's derivative financial instruments and their classification on Consolidated Balance Sheet	'
	The tables below present the fair value of the Company’s derivative financial instruments as well as their classification on the Consolidated Balance Sheets as of September 30, 2014 and December 31, 2013 (dollars in thousands):
		Asset Derivatives										Liability Derivatives
				Fair Value at:										Fair Value at:
		Balance		September 30,				December 31,				Balance		September 30,				December 31,
		Sheet Location		2014				2013				Sheet Location		2014				2013
	Derivatives designated as hedging instruments:
	Interest rate products	Other assets		$	299			—				Other liabilities		$	2,382			4,965
	Derivatives not designated as hedging instruments:
	Interest rate products	Other assets		$	—			$	—			Other liabilities		$	—			$	—
Effect of Company's derivative financial instruments on Consolidated Statements of Operation	'
	The tables below present the effect of the Company’s derivative financial instruments on the Consolidated Statements of Operations for the three and nine months ended September 30, 2014 and 2013 (dollars in thousands):
			Amount of Gain or (Loss) Recognized in OCI on Derivative (Effective Portion)								Location of Gain or (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)		Amount of Gain or (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)								Location of Gain or (Loss) Recognized in Income on Derivative (Ineffective Portion and Amount Excluded from Effectiveness Testing)	Amount of Gain or (Loss) Recognized in Income on Derivative (Ineffective Portion and Amount Excluded from Effectiveness Testing)
	Derivatives in Cash Flow Hedging Relationships		2014				2013						2014				2013					2014		2013
	For the Three Months Ended September 30,
	Interest rate products		$	362			$	(386	)		Interest expense		$	(1,130	)		$	(1,635	)		Interest expense	$	—	$	—
	For the Nine Months Ended September 30,
	Interest rate products		$	611			$	(334	)		Interest expense		$	(3,809	)		$	(5,180	)		Interest expense	$	3	$	—
Effect of Company's derivatives not designated as hedging instruments on the Consolidated Statements of Operations	'
	Derivatives Not Designated as Hedging Instruments		Location of Gain or (Loss) Recognized in Income on Derivative		Amount of Gain or (Loss) Recognized in Income on Derivative
					2014				2013
	For the Three Months Ended September 30,
	Interest rate products		Interest and other income/(loss), net		$	—			$	280
	For the Nine Months Ended September 30,
	Interest rate products		Interest and other income/(loss), net		$	—			$	275
Offsetting Assets [Table Text Block]	'
	Offsetting of Derivative Assets
															Gross Amounts Not Offset in the Consolidated Balance Sheets
			Gross Amounts of Recognized Assets				Gross Amounts Offset in the Consolidated Balance Sheets				Net Amounts of Assets Presented in the Consolidated Balance Sheets (a)				Financial Instruments				Cash Collateral Received			Net Amount
	September 30, 2014		$	299			$	—			$	299			$	(253	)		$	—		$	46
	December 31, 2013		$	—			$	—			$	—			$	—			$	—		$	—
	(a) 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.
Offsetting Liabilities [Table Text Block]	'
	Offsetting of Derivative Liabilities
															Gross Amounts Not Offset in the Consolidated Balance Sheets
			Gross Amounts of Recognized Liabilities				Gross Amounts Offset in the Consolidated Balance Sheets				Net Amounts of Liabilities Presented in the Consolidated Balance Sheets (b)				Financial Instruments				Cash Collateral Posted			Net Amount
	September 30, 2014		$	2,382			$	—			$	2,382			$	(253	)		$	—		$	2,129
	December 31, 2013		$	4,965			$	—			$	4,965			$	—			$	—		$	4,965
	(b) 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.
United Dominion Reality L.P. [Member]	'
Entity Information [Line Items]	'
Outstanding interest rate derivatives	'
	As of September 30, 2014, the Operating Partnership had the following outstanding interest rate derivatives designated as cash flow hedges of interest rate risk (dollars in thousands):
	Interest Rate Derivative		Number of Instruments		Notional
	Interest rate swaps		2		$	96,974
	Interest rate caps		5		$	255,561
	Derivatives not designated as hedges are not speculative and are used to manage the Company’s exposure to interest rate movements and other identified risks but do not meet the strict hedge accounting requirements of GAAP. Changes in the fair value of derivatives not designated in hedging relationships are recorded directly in earnings and resulted in no adjustment to earnings for the three and nine months ended September 30, 2014 and gains/(losses) of zero and $(5,000) for the three and nine months ended September 30, 2013, respectively.
	As of September 30, 2014, the Operating Partnership did not have any outstanding derivatives that were not designated as hedges in qualifying hedging relationships.
Fair value of Company's derivative financial instruments and their classification on Consolidated Balance Sheet	'
	The table below presents the fair value of the Operating Partnership’s derivative financial instruments as well as their classification on the Consolidated Balance Sheets as of September 30, 2014 and December 31, 2013 (dollars in thousands):
		Asset Derivatives										Liability Derivatives
				Fair Value at:										Fair Value at:
		Balance		September 30,				December 31,				Balance		September 30,				December 31,
		Sheet Location		2014				2013				Sheet Location		2014				2013
	Derivatives designated as hedging instruments:
	Interest rate products	Other assets		$	5			$	—			Other liabilities		$	1,324			$	2,731
	Derivatives not designated as hedging instruments:
	Interest rate products	Other assets		$	—			$	—			Other liabilities		$	—			$	—
Effect of Company's derivative financial instruments on Consolidated Statements of Operation	'
	The tables below present the effect of the derivative financial instruments on the Consolidated Statements of Operations for the three and nine months ended September 30, 2014 and 2013 (dollars in thousands):
			Amount of Gain or (Loss) Recognized in OCI on Derivatives (Effective Portion)								Location of Gain or (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)
	Derivatives in Cash Flow Hedging Relationships												Amount of Gain or (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)
			2014				2013						2014				2013
	For the Three Months Ended September 30,
	Interest rate products		$	(3	)		$	(201	)		Interest expense		$	(588	)		$	(590	)
	For the Nine Months Ended September 30,
	Interest rate products		$	(194	)		$	(284	)		Interest expense		$	(1,784	)		$	(2,041	)
Effect of Company's derivatives not designated as hedging instruments on the Consolidated Statements of Operations	'
		Derivatives Not Designated as Hedging Instruments		Location of Gain or (Loss) Recognized in Income on Derivatives		Amount of Gain or (Loss) Recognized in Income on Derivatives
						2014				2013
		For the Three Months Ended September 30,
		Interest rate products		Other operating expenses		$	—			$	—
		For the Nine Months Ended September 30,
		Interest rate products		Other operating expenses		$	—			$	(5	)
Offsetting Assets [Table Text Block]	'
	The General Partner has elected not to offset derivative positions in the consolidated financial statements. The table below presents the effect on the Operating Partnership’s financial position had the General Partner made the election to offset its derivative positions as of September 30, 2014 and December 31, 2013:
	Offsetting of Derivative Assets
															Gross Amounts Not Offset in the Consolidated Balance Sheets
			Gross Amounts of Recognized Assets				Gross Amounts Offset in the Consolidated Balance Sheets				Net Amounts of Assets Presented in the Consolidated Balance Sheets (a)				Financial Instruments				Cash Collateral Received			Net Amount
	September 30, 2014		$	5			$	—			$	5			$	—			$	—		$	5
	December 31, 2013		$	—			$	—			$	—			$	—			$	—		$	—
	(a) 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.
Offsetting Liabilities [Table Text Block]	'
	Offsetting of Derivative Liabilities
															Gross Amounts Not Offset in the Consolidated Balance Sheets
			Gross Amounts of Recognized Liabilities				Gross Amounts Offset in the Consolidated Balance Sheets				Net Amounts of Liabilities Presented in the Consolidated Balance Sheets (b)				Financial Instruments				Cash Collateral Posted			Net Amount
	September 30, 2014		$	1,324			$	—			$	1,324			$	—			$	—		$	1,324
	December 31, 2013		$	2,731			$	—			$	2,731			$	—			$	—		$	2,731
	(b) 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.

Commitments_and_Contingencies_1

Commitments and Contingencies (Tables)	9 Months Ended
	Sep. 30, 2014
Commitments and Contingencies Disclosure [Abstract]	'
Real estate commitments	'
	The following summarizes the Company’s real estate commitments at September 30, 2014 (dollars in thousands):
		Number of	Costs Incurred			Expected Costs			Average Ownership
		Properties	to Date (a)			to Complete			Stake
	Wholly-owned — under development	3	$	321,607	(b)	$	78,793		100	%
	Wholly-owned — redevelopment	1	80,619		(b)	17,381			100	%
	Joint ventures:
	Unconsolidated joint ventures	2	158,986			143,981		(c)	51	%
	Participating loan investments	1	43,822		(d)	48,187		(e)	0	%
			$	605,034		$	288,342
	(a)	Represents 100% of project costs incurred to date.
	(b)	Costs incurred to date include $26.8 million and $2.1 million of accrued fixed assets for development and redevelopment, respectively.
	(c)	Represents UDR’s contributed and remaining equity commitment in unconsolidated joint ventures.
	(d)	Represents the participating loan balance funded as of September 30, 2014.
	(e)	Represents UDR’s remaining participating loan commitment for Steele Creek.

Reportable_Segment_Tables

Reportable Segment (Tables)	9 Months Ended
	Sep. 30, 2014
Segment Reporting [Abstract]	'
Summary of rental income and NOI for UDRs reportable segments and reconciliation of NOI to loss from continuing operations	'
	The following table details rental income and NOI from continuing and discontinued operations for UDR’s reportable segments for the three and nine months ended September 30, 2014 and 2013, and reconciles NOI to Net Income/(Loss) Attributable to UDR, Inc. in the Consolidated Statements of Operations (dollars in thousands):
		Three Months Ended September 30, (a)						Nine Months Ended September 30, (b)
		2014			2013			2014			2013
	Reportable apartment home segment rental income
	Same-Store Communities
	West Region	$	68,275		$	64,195		$	189,075		$	177,884
	Mid-Atlantic Region	40,479			40,164			121,356			119,937
	Southeast Region	27,210			25,851			80,578			76,763
	Northeast Region	20,721			19,806			45,331			43,441
	Southwest Region	13,859			13,293			40,949			39,012
	Non-Mature Communities/Other	33,064			27,070			121,756			106,256
	Total consolidated rental income	$	203,608		$	190,379		$	599,045		$	563,293
	Reportable apartment home segment NOI
	Same-Store Communities
	West Region	$	49,110		$	45,699		$	136,587		$	126,860
	Mid-Atlantic Region	27,622			27,629			83,581			83,287
	Southeast Region	17,480			16,560			53,329			49,866
	Northeast Region	15,571			14,678			33,361			31,409
	Southwest Region	8,509			7,983			25,130			23,751
	Non-Mature Communities/Other	21,522			16,094			80,342			67,439
	Total consolidated NOI	139,814			128,643			412,330			382,612
	Reconciling items:
	Joint venture management and other fees	3,165			3,207			9,599			9,347
	Property management	(5,599		)	(5,236		)	(16,474		)	(15,491		)
	Other operating expenses	(2,012		)	(1,787		)	(6,118		)	(5,237		)
	Real estate depreciation and amortization	(89,339		)	(84,266		)	(266,748		)	(252,839		)
	General and administrative	(11,554		)	(11,364		)	(36,078		)	(30,706		)
	Casualty-related recoveries/(charges), net	—			6,460			(500		)	12,253
	Other depreciation and amortization	(1,385		)	(1,176		)	(3,658		)	(3,460		)
	Income/(loss) from unconsolidated entities	(939		)	(3,794		)	(4,932		)	(6,081		)
	Interest expense	(33,087		)	(30,939		)	(97,662		)	(92,723		)
	Interest and other income/(expense), net	9,061			829			11,902			3,291
	Tax benefit/(expense), net	2,490			2,658			8,049			7,314
	Gain/(loss) on sale of real estate owned, net of tax	31,377			—			82,380			—
	Net (income)/loss attributable to redeemable noncontrolling interests in the Operating Partnership	(1,447		)	(84		)	(3,171		)	(198		)
	Net (income)/loss attributable to noncontrolling interests	4			37			(2		)	30
	Net income/(loss) attributable to UDR, Inc.	$	40,549		$	3,188		$	88,917		$	8,112
	(a)	Same-Store Community population consisted of 36,268 apartment homes.
	(b)	Same-Store Community population consisted of 35,177 apartment homes.
Details of assets of UDR's reportable segments	'
	The following table details the assets of UDR’s reportable segments as of September 30, 2014 and December 31, 2013 (dollars in thousands):
		September 30,			December 31,
		2014			2013
	Reportable apartment home segment assets:
	Same-Store Communities:
	West Region	$	2,591,838		$	2,412,091
	Mid-Atlantic Region	1,404,730			1,395,772
	Southeast Region	783,641			785,134
	Northeast Region	1,073,905			1,066,260
	Southwest Region	438,982			434,875
	Non-Mature Communities/Other	2,135,195			2,113,845
	Total assets	8,428,291			8,207,977
	Accumulated depreciation	(2,379,033		)	(2,208,794		)
	Total assets — net book value	6,049,258			5,999,183
	Reconciling items:
	Cash and cash equivalents	14,605			30,249
	Restricted cash	23,969			22,796
	Deferred financing costs, net	24,344			26,924
	Notes receivable, net	18,318			83,033
	Investment in and advances to unconsolidated joint ventures, net	650,441			507,655
	Other assets	117,153			137,882
	Total consolidated assets	$	6,898,088		$	6,807,722

Reportable_Segments_UNITED_DOM1

Reportable Segments (UNITED DOMINION REALTY, L.P.) (Tables) (United Dominion Reality L.P. [Member])	9 Months Ended
	Sep. 30, 2014
United Dominion Reality L.P. [Member]	'
Entity Information [Line Items]	'
Reportable segments information	'
	The following table details rental income and NOI from continuing and discontinued operations for the Operating Partnership’s reportable segments for the three and nine months ended September 30, 2014 and 2013, and reconciles NOI to Net income/(loss) attributable to OP unitholders in the Consolidated Statements of Operations (dollars in thousands):
		Three Months Ended September 30, (a)						Nine Months Ended September 30, (b)
		2014			2013			2014			2013
	Reportable apartment home segment rental income
	Same-Store Communities
	West Region	$	49,279		$	46,246		$	144,252		$	135,418
	Mid-Atlantic Region	17,169			17,105			51,779			51,095
	Southeast Region	11,368			10,841			33,753			32,177
	Northeast Region	14,968			14,331			28,410			27,414
	Southwest Region	6,667			6,508			19,873			19,098
	Non-Mature Communities/Other	7,993			8,966			36,589			41,564
	Total consolidated rental income	$	107,444		$	103,997		$	314,656		$	306,766
	Reportable apartment home segment NOI
	Same-Store Communities
	West Region	$	35,801		$	33,307		$	105,375		$	97,533
	Mid-Atlantic Region	11,422			11,483			34,888			34,689
	Southeast Region	7,327			6,957			22,286			20,898
	Northeast Region	11,609			10,789			21,448			20,083
	Southwest Region	4,192			4,040			12,578			11,987
	Non-Mature Communities/Other	5,402			5,417			26,563			29,383
	Total consolidated NOI	75,753			71,993			223,138			214,573
	Reconciling items:
	Property management	(2,955		)	(2,860		)	(8,653		)	(8,436		)
	Other operating expenses	(1,484		)	(1,405		)	(4,371		)	(4,215		)
	Real estate depreciation and amortization	(45,043		)	(44,857		)	(134,011		)	(135,552		)
	General and administrative	(6,939		)	(6,855		)	(21,368		)	(18,324		)
	Casualty-related recoveries/(charges), net	—			3,807			(500		)	8,083
	Interest expense	(10,457		)	(8,773		)	(30,629		)	(27,085		)
	Gain/(loss) on sale of real estate owned	—			—			40,687			—
	Net (income)/loss attributable to noncontrolling interests	(238		)	(39		)	(697		)	(151		)
	Net income/(loss) attributable to OP unitholders	$	8,637		$	11,011		$	63,596		$	28,893
	(a)	Same-store consists of 19,518 apartment homes.
	(b)	Same-store consists of 19,010 apartment homes.
	The following table details the assets of the Operating Partnership’s reportable segments as of September 30, 2014 and December 31, 2013 (dollars in thousands):
		September 30,			December 31, 2013
		2014
	Reportable apartment home segment assets
	Same-Store Communities
	West Region	$	1,742,559		$	1,733,144
	Mid-Atlantic Region	710,277			706,447
	Southeast Region	331,727			328,150
	Northeast Region	776,310			770,937
	Southwest Region	227,886			226,252
	Non-Mature Communities/Other	430,464			423,550
	Total assets	4,219,223			4,188,480
	Accumulated depreciation	(1,358,123		)	(1,241,574		)
	Total assets - net book value	2,861,100			2,946,906
	Reconciling items:
	Cash and cash equivalents	1,484			1,897
	Restricted cash	13,989			13,526
	Deferred financing costs, net	4,783			5,848
	Other assets	25,070			25,064
	Total consolidated assets	$	2,906,426		$	2,993,241

Consolidation_and_Basis_of_Pre2

Consolidation and Basis of Presentation (Details) (USD $)	Sep. 30, 2014
In Thousands, except Share data, unless otherwise specified
Organization, Consolidation and Presentation of Financial Statements [Abstract]	'
Deferred Tax Assets, Net	$9,134
Consolidation And Basis Of Presentation (Textual) [Abstract]	'
Operating Partnership outstanding units	183,278,698
OP units outstanding related to general partner	174,111,227
Percentage of units owned by UDR	95.00%

Consolidation_and_Basis_of_Pre3

Consolidation and Basis of Presentation (UNITED DOMINION REALTY, L.P.) (Details)	3 Months Ended		9 Months Ended	12 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Dec. 31, 2012	Dec. 31, 2013
	Apartment_Homes		Apartment_Homes
	Markets		Markets
Entity Information [Line Items]	'	'	'	'	'
Number of apartments owned (in apartments homes)	40,477	'	40,477	'	'
Operating Partnership outstanding units	183,278,698	'	183,278,698	'	'
OP units outstanding related to general partner	174,111,227	'	174,111,227	'	'
Percentage of units owned by UDR	95.00%	'	95.00%	'	'
United Dominion Reality L.P. [Member]	'	'	'	'	'
Entity Information [Line Items]	'	'	'	'	'
Rental revenues percent of General Partner's consolidated rental revenues	53.00%	55.00%	53.00%	54.00%	'
Number of markets operating within (in markets)	17	'	17	'	'
Number of apartments owned (in apartments homes)	20,753	'	20,753	'	'
OP units outstanding related to general partner	110,883	'	110,883	'	110,883
OP units outstanding related to limited partner	183,167,815	'	183,167,815	'	183,167,815

Significant_Accounting_Policie5

Significant Accounting Policies (Details) (USD $)	1 Months Ended	3 Months Ended		9 Months Ended		12 Months Ended
	Jul. 31, 2014	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2012	Dec. 31, 2013
Accounting Policies [Line Items]	'	'	'	'	'	'	'
Gain (Loss) on Sale of Notes Receivable	$8,400,000	'	'	'	'	'	'
Current Income Tax Expense (Benefit)	'	'	'	0	'	'	'
Significant Accounting Policies (Textual) [Abstract]	'	'	'	'	'	'	'
Notes receivable	'	18,318,000	'	18,318,000	'	'	83,033,000
Note maturity public capital threshold	'	'	'	5,000,000	'	'	'
Note receivable interest income	'	444,000	1,100,000	2,985,000	3,100,000	'	'
Net of a valuation allowance	'	1,433,000	'	1,433,000	'	'	'
Tax benefit/(expense), net	'	-2,492,000	-2,658,000	-8,011,000	-7,314,000	'	'
Recognition and evaluation of tax position, whether a tax position is more likely	'	'not (greater than 50 percent probability)	'	'	'	'	'
Unrecognized tax benefit, accrued interest or penalties due to examination	'	0	'	0	'	'	'
Proceeds from Sale and Collection of Notes Receivable	'	'	'	64,715,000	-2,680,000	'	'
Interest Income, Related Party	'	'	'	184,000	'	547,000	'
Note Due March 2014 Related Party [Domain]	'	'	'	'	'	'	'
Significant Accounting Policies (Textual) [Abstract]	'	'	'	'	'	'	'
Basis spread on variable rate	'	35000.00%	'	35000.00%	'	'	'
Note due October 2014 - related party [Member]	'	'	'	'	'	'	'
Significant Accounting Policies (Textual) [Abstract]	'	'	'	'	'	'	'
Notes receivable	'	0	'	0	'	'	40,800,000
Notes receivable interest rate	'	'	'	0.00%	'	'	'
Note due February 2017 [Member]	'	'	'	'	'	'	'
Significant Accounting Policies (Textual) [Abstract]	'	'	'	'	'	'	'
Notes receivable	'	15,818,000	'	15,818,000	'	'	14,580,000
Notes receivable interest rate	'	'	'	10.00%	'	'	'
Issuance of notes receivable	'	1,238,000	'	'	'	'	'
Note due June 2022 [Member]	'	'	'	'	'	'	'
Significant Accounting Policies (Textual) [Abstract]	'	'	'	'	'	'	'
Notes receivable	'	0	'	0	'	'	26,253,000
Notes receivable interest rate	'	'	'	0.00%	'	'	'
Note receivable, unamortized discount	'	0	'	0	'	'	247,000
Loan amount	'	26,500,000	'	26,500,000	'	'	'
Discount rate on note receivable	'	'	'	7.25%	'	'	'
Proceeds from Sale and Collection of Notes Receivable	36,000,000	'	'	'	'	'	'
Other [Member]	'	'	'	'	'	'	'
Significant Accounting Policies (Textual) [Abstract]	'	'	'	'	'	'	'
Notes receivable	'	2,500,000	'	2,500,000	'	'	1,400,000
Notes receivable interest rate	'	'	'	8.00%	'	'	'
Issuance of notes receivable	'	'	'	1,100,000	'	'	'
Aggregate Commitment on Note Receivable	'	2,500,000	'	2,500,000	'	'	'
RedeemableNoncontrollingInterest [Member]	'	'	'	'	'	'	'
Accounting Policies [Line Items]	'	'	'	'	'	'	'
Comprehensive (loss)/income attributable to non-controlling interests	'	57,000	45,000	163,000	'	196,000	'
Unconsolidated Joint Venture Two Stoughton Massachusetts [Member]	'	'	'	'	'	'	'
Accounting Policies [Line Items]	'	'	'	'	'	'	'
Equity Method Investment, Ownership Percentage	'	'	'	'	'	'	95.00%
Significant Accounting Policies (Textual) [Abstract]	'	'	'	'	'	'	'
Joint Venture Number of Operating Communities Owned	'	1	'	1	'	'	'
Bridge Loan	'	$40,800,000	'	$40,800,000	'	'	'
Number of extension options on loan	'	'	'	2	'	'	'
Extension period of option on loan	'	'	'	'3 months	'	'	'

Real_Estate_Owned_Details

Real Estate Owned (Details) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Summary of carrying amounts for real estate owned (at cost)	'	'
Land	$1,955,007	$1,847,127
Depreciable property - held and used:	'	'
Building, Improvements, and Furniture, Fixtures and Equipment	6,151,677	5,876,717
Under development:	'	'
Under development	321,094	466,002
Real estate owned	8,428,291	8,207,977
Accumulated depreciation	-2,379,033	-2,208,794
Real estate owned, net	6,049,258	5,999,183
Land [Member]	'	'
Depreciable property - held and used:	'	'
Real Estate Held-for-sale	0	10,751
Under development:	'	'
Under development	47,038	110,769
Building and Building Improvements [Member]	'	'
Depreciable property - held and used:	'	'
Real Estate Held-for-sale	0	5,969
Construction in progress [Member]	'	'
Under development:	'	'
Under development	$274,569	$356,644

Real_Estate_Owned_Details_Text

Real Estate Owned (Details Textual) (USD $)

3 Months Ended

9 Months Ended

12 Months Ended

3 Months Ended

9 Months Ended

12 Months Ended

3 Months Ended

9 Months Ended

9 Months Ended

3 Months Ended

9 Months Ended

9 Months Ended

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Dec. 31, 2013

Dec. 31, 2012

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2013

Dec. 31, 2013

Dec. 31, 2012

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Mar. 31, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Apartment_Homes

States

Apartment_Homes

States

Apartment_Homes

New York Properties [Member]

United Dominion Reality L.P. [Member]

United Dominion Reality L.P. [Member]

United Dominion Reality L.P. [Member]

United Dominion Reality L.P. [Member]

United Dominion Reality L.P. [Member]

United Dominion Reality L.P. [Member]

United Dominion Reality L.P. [Member]

United Dominion Reality L.P. [Member]

Operating Community [Member]

Operating Community [Member]

Operating Community [Member]

Operating Community [Member]

Development Community [Member]

Land [Member]

Land [Member]

Land [Member]

Lightbox [Member]

Land [Member]

Waterscape [Member]

Grandview [Member]

States

Communities

Communities

Apartment_Homes

Apartment_Homes

New York Properties [Member]

Unconsolidated Joint Venture Four Texas [Member]

United Dominion Reality L.P. [Member]

Unconsolidated Joint Venture Vitruvian Park [Member]

Unconsolidated Joint Venture Vitruvian Park [Member]

Communities

Apartment_Homes

Apartment_Homes

States

States

Communities

Communities

Communities

Communities

Real Estate Properties [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Communities Held For Sale

1

1

'

1

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Real Estate Owned (Textual) [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Number of states in which there are owned and consolidated communities

10

10

'

10

'

'

'

'

9

'

9

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Number of apartment homes owned and consolidated by the Company

40,477

40,477

'

40,477

'

'

'

'

20,753

'

20,753

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Joint Venture and Partnership Number of Operating Communities Owned

141

141

'

141

'

'

'

'

67

'

67

'

'

'

'

'

'

'

8

'

1

'

'

6

'

'

'

'

Development costs excluding direct costs and capitlized interest

'

$1,720,000

$2,400,000

$7,230,000

$8,500,000

'

'

'

$496,000

$618,000

$1,793,000

'

$2,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Interest capitalized during period

'

5,200,000

6,600,000

15,400,000

23,200,000

'

'

'

800,000

1,700,000

2,800,000

'

4,400,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Number of Apartments Owned

'

'

'

1,904

'

914

'

'

'

'

'

'

'

914

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Impairment of Long-Lived Assets Held-for-use

'

'

'

'

'

'

'

0

'

'

'

'

'

'

'

0

'

'

'

'

'

'

'

'

'

'

'

'

Other Cost and Expense, Operating

'

2,009,000

1,775,000

6,097,000

5,211,000

'

'

'

1,484,000

1,405,000

4,371,000

'

4,215,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Property, Plant and Equipment, Additions

'

'

'

129,400,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

45,500,000

77,800,000

75,200,000

'

Proceeds from Sale of Property, Plant, and Equipment

'

'

'

237,700,000

'

'

'

'

'

'

48,700,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Payments for (Proceeds from) Investments

'

'

'

233,913,000

140,834,000

'

'

'

'

'

47,922,000

'

0

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Gains/(loss) on sales of real estate, net of tax

'

31,302,000

0

82,305,000

0

'

'

'

0

0

40,687,000

'

0

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Gain (Loss) on Disposition of Property Plant Equipment

'

100,000

'

82,400,000

'

'

'

'

'

'

24,400,000

'

'

'

'

'

31,300,000

81,200,000

'

39,600,000

'

1,100,000

1,100,000

'

'

'

'

100,000

Communities Sold

'

'

'

6

0

2

'

'

'

'

1

0

0

2

'

'

'

1

'

'

'

'

'

'

'

'

'

1

Number of Communities Acquired

2

2

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Number of Apartment Homes Acquired

0

358

0

'

0

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Casualty-related (recoveries)/charges, net

'

'

'

'

'

'

'

'

0

-3,807,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Casualty (Recoveries)/Charges

'

$0

$6,460,000

($500,000)

$12,253,000

'

($12,253,000)

'

$0

$3,807,000

($500,000)

'

$8,083,000

'

($8,083,000)

'

'

'

'

'

'

'

'

'

'

'

'

'

Real_Estate_Owned_UNITED_DOMIN2

Real Estate Owned (UNITED DOMINION REALTY, L.P.) (Details) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Summary of carrying amounts for real estate owned (at cost)	'	'
Land	$1,955,007	$1,847,127
Under development:	'	'
Under development	321,094	466,002
Real estate owned	8,428,291	8,207,977
Accumulated depreciation	-2,379,033	-2,208,794
Real estate owned, net	6,049,258	5,999,183
Land [Member]	'	'
Under development:	'	'
Under development	47,038	110,769
Construction in progress [Member]	'	'
Under development:	'	'
Under development	274,569	356,644
United Dominion Reality L.P. [Member]	'	'
Summary of carrying amounts for real estate owned (at cost)	'	'
Land	998,797	1,004,447
Depreciable property - held and used:	'	'
Building, improvements, and furniture, fixture and equipment	3,100,598	3,103,970
Under development:	'	'
Under development	119,315	80,063
Real estate owned	4,219,223	4,188,480
Accumulated depreciation	-1,358,123	-1,241,574
Real estate owned, net	2,861,100	2,946,906
United Dominion Reality L.P. [Member] | Land [Member]	'	'
Under development:	'	'
Under development	9,447	9,447
United Dominion Reality L.P. [Member] | Construction in progress [Member]	'	'
Under development:	'	'
Under development	$110,381	$70,616

Real_Estate_Owned_UNITED_DOMIN3

Real Estate Owned (UNITED DOMINION REALTY, L.P.) (Details Textual) (USD $)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013	Dec. 31, 2012
	Apartment_Homes	Communities	Communities	Apartment_Homes		Communities
	Communities	Apartment_Homes	States
	States		Apartment_Homes
Real Estate Owned (Textual) [Abstract]	'	'	'	'	'	'
Number of communities owned (in communities)	141	'	141	'	'	'
Number of states operating within (in states)	10	'	10	'	'	'
Number of apartments owned (in apartments homes)	40,477	'	40,477	'	'	'
Number of communities acquired apartment homes are within	0	0	0	'	'	0
Number of Apartment Homes Acquired	0	0	'	0	'	'
Development costs excluding direct costs and capitlized interest	1,720,000	$2,400,000	$7,230,000	$8,500,000	'	'
Interest capitalized during period	5,200,000	6,600,000	15,400,000	23,200,000	'	'
Other Cost and Expense, Operating	2,009,000	1,775,000	6,097,000	5,211,000	'	'
Proceeds from Sale of Property, Plant, and Equipment	'	'	237,700,000	'	'	'
Gains/(loss) on sales of real estate, net of tax	31,302,000	0	82,305,000	0	'	'
Communities Sold	'	'	6	0	2	'
Casualty (Recoveries)/Charges	0	6,460,000	-500,000	12,253,000	'	-12,253,000
Gain (Loss) on Disposition of Property Plant Equipment	100,000	'	82,400,000	'	'	'
Payments for (Proceeds from) Investments	'	'	233,913,000	140,834,000	'	'
United Dominion Reality L.P. [Member]	'	'	'	'	'	'
Real Estate Owned (Textual) [Abstract]	'	'	'	'	'	'
Number of communities owned (in communities)	67	'	67	'	'	'
Number of states operating within (in states)	9	'	9	'	'	'
Number of apartments owned (in apartments homes)	20,753	'	20,753	'	'	'
Development costs excluding direct costs and capitlized interest	496,000	618,000	1,793,000	2,000,000	'	'
Interest capitalized during period	800,000	1,700,000	2,800,000	4,400,000	'	'
Other Cost and Expense, Operating	1,484,000	1,405,000	4,371,000	4,215,000	'	'
Proceeds from Sale of Property, Plant, and Equipment	'	'	48,700,000	'	'	'
Gains/(loss) on sales of real estate, net of tax	0	0	40,687,000	0	'	'
Communities Sold	'	'	1	0	2	'
Casualty-related (recoveries)/charges, net	0	-3,807,000	'	'	'	'
Casualty (Recoveries)/Charges	0	3,807,000	-500,000	8,083,000	'	-8,083,000
Gain (Loss) on Disposition of Property Plant Equipment	'	'	24,400,000	'	'	'
Payments for (Proceeds from) Investments	'	'	47,922,000	0	'	'
New York Properties [Member]	'	'	'	'	'	'
Real Estate Owned (Textual) [Abstract]	'	'	'	'	'	'
Impairment of Long-Lived Assets Held-for-use	0	'	'	'	'	'
New York Properties [Member] | United Dominion Reality L.P. [Member]	'	'	'	'	'	'
Real Estate Owned (Textual) [Abstract]	'	'	'	'	'	'
Impairment of Long-Lived Assets Held-for-use	0	'	'	'	'	'

Discontinued_Operations_Detail

Discontinued Operations (Details) (USD $)

3 Months Ended

9 Months Ended

12 Months Ended

3 Months Ended

9 Months Ended

3 Months Ended

9 Months Ended

3 Months Ended

9 Months Ended

12 Months Ended

9 Months Ended

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Dec. 31, 2013

Dec. 31, 2012

Sep. 30, 2014

Sep. 30, 2014

Mar. 31, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2013

Dec. 31, 2013

Sep. 30, 2014

Operating Community [Member]

Operating Community [Member]

Land [Member]

Land [Member]

United Dominion Reality L.P. [Member]

United Dominion Reality L.P. [Member]

United Dominion Reality L.P. [Member]

United Dominion Reality L.P. [Member]

United Dominion Reality L.P. [Member]

United Dominion Reality L.P. [Member]

United Dominion Reality L.P. [Member]

Operating Community [Member]

Disposal Group, Including Discontinued Operation, Operating Income (Loss)

$6,000

$884,000

($103,000)

$2,567,000

'

'

'

'

'

'

'

'

'

'

'

'

'

Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax

75,000

0

75,000

'

'

0

'

'

'

'

'

'

'

'

'

'

'

Gain (Loss) on Disposition of Property Plant Equipment

100,000

'

82,400,000

'

'

'

31,300,000

81,200,000

1,100,000

1,100,000

'

'

24,400,000

'

'

'

39,600,000

Discontinued Operations (Textual) [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Communities sold (in communities)

'

'

6

0

2

'

'

1

'

'

'

'

1

0

0

2

'

Apartment Homes Sold

'

'

1,904

'

914

'

'

'

'

'

'

'

'

'

'

914

'

Communities held for sale (in communities)

1

'

1

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Summary of income from discontinued operations

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Rental income

21,000

2,462,000

147,000

7,130,000

'

'

'

'

'

'

0

2,438,000

0

'

7,016,000

'

'

Rental expenses

11,000

970,000

225,000

2,733,000

'

'

'

'

'

'

0

869,000

0

'

2,467,000

'

'

Property management

1,000

68,000

4,000

196,000

'

'

'

'

'

'

0

67,000

0

'

193,000

'

'

Real estate depreciation

0

528,000

0

1,608,000

'

'

'

'

'

'

0

524,000

0

'

1,590,000

'

'

Other operating expenses

3,000

12,000

21,000

26,000

'

'

'

'

'

'

'

'

'

'

'

'

'

Income tax benefit/(expense)

-2,000

0

38,000

0

'

'

'

'

'

'

'

'

'

'

'

'

'

Income/(loss) from discontinued operations, net of tax

79,000

884,000

10,000

2,567,000

'

2,567,000

'

'

'

'

0

978,000

0

'

2,766,000

'

'

Income/(loss) from discontinued operations attributable to common stockholders

$73,000

$852,000

$6,000

$2,475,000

'

'

'

'

'

'

$0

$978,000

$0

'

$2,766,000

'

'

Discontinued_Operations_UNITED2

Discontinued Operations (UNITED DOMINION REALTY, L.P.) (Details) (USD $)

3 Months Ended

9 Months Ended

12 Months Ended

3 Months Ended

9 Months Ended

12 Months Ended

3 Months Ended

9 Months Ended

3 Months Ended

9 Months Ended

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Dec. 31, 2013

Dec. 31, 2012

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2013

Dec. 31, 2013

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Mar. 31, 2014

Sep. 30, 2014

United Dominion Reality L.P. [Member]

United Dominion Reality L.P. [Member]

United Dominion Reality L.P. [Member]

United Dominion Reality L.P. [Member]

United Dominion Reality L.P. [Member]

United Dominion Reality L.P. [Member]

Operating Community [Member]

Operating Community [Member]

Operating Community [Member]

Land [Member]

Land [Member]

United Dominion Reality L.P. [Member]

Entity Information [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Gains/(loss) on sales of real estate, net of tax

$31,302,000

$0

$82,305,000

$0

'

'

$0

$0

$40,687,000

'

$0

'

'

'

'

'

'

Gain (Loss) on Disposition of Property Plant Equipment

100,000

'

82,400,000

'

'

'

'

'

24,400,000

'

'

'

31,300,000

81,200,000

39,600,000

1,100,000

1,100,000

Discontinued Operations (Textual) [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Communities sold (in communities)

'

'

6

0

2

'

'

'

1

0

0

2

'

1

'

'

'

Communities held for sale (in communities)

1

'

1

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Summary of income from discontinued operations

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Rental income

21,000

2,462,000

147,000

7,130,000

'

'

0

2,438,000

0

'

7,016,000

'

'

'

'

'

'

Rental expenses

11,000

970,000

225,000

2,733,000

'

'

0

869,000

0

'

2,467,000

'

'

'

'

'

'

Property management

1,000

68,000

4,000

196,000

'

'

0

67,000

0

'

193,000

'

'

'

'

'

'

Real estate depreciation

0

528,000

0

1,608,000

'

'

0

524,000

0

'

1,590,000

'

'

'

'

'

'

Income/(loss) from discontinued operations

79,000

884,000

10,000

2,567,000

'

2,567,000

0

978,000

0

'

2,766,000

'

'

'

'

'

'

Income (loss) from discontinued operations attributable to OP unitholders

$73,000

$852,000

$6,000

$2,475,000

'

'

$0

$978,000

$0

'

$2,766,000

'

'

'

'

'

'

Apartment Homes Sold

'

'

1,904

'

914

'

'

'

'

'

'

914

'

'

'

'

'

Joint_Ventures_Details

Joint Ventures (Details) (USD $)

3 Months Ended

9 Months Ended

12 Months Ended

3 Months Ended

9 Months Ended

12 Months Ended

3 Months Ended

9 Months Ended

In Thousands, unless otherwise specified

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Dec. 31, 2012

Dec. 31, 2013

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Sep. 30, 2014

Mar. 31, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2013

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Communities

Communities

Unconsolidated Joint Ventures [Member]

Unconsolidated Joint Ventures [Member]

Unconsolidated Joint Ventures [Member]

Unconsolidated Joint Ventures [Member]

Unconsolidated Joint Ventures [Member]

Unconsolidated Joint Venture Two Stoughton Massachusetts [Member]

Operating Community [Member]

Operating Community [Member]

Operating Community [Member]

Operating Community [Member]

Operating Community [Member]

Operating Community [Member]

Operating Community [Member]

Operating Community [Member]

Operating Community [Member]

Operating Community [Member]

Operating Community [Member]

Development Community [Member]

Development Community [Member]

Development Community [Member]

Development Community [Member]

Development Community [Member]

Development Community [Member]

Development Community [Member]

Land [Member]

Land [Member]

Land [Member]

Land [Member]

Land [Member]

Unconsolidated Joint Venture UDR Met Life I Partnership [Member]

Unconsolidated Joint Venture UDR Met Life I Partnership [Member]

Unconsolidated Joint Venture UDR Met Life I Partnership [Member]

Unconsolidated Joint Venture UDR MetLife II Partnership [Member]

Unconsolidated Joint Venture UDR MetLife II Partnership [Member]

Unconsolidated Joint Venture Vitruvian Park [Member]

Unconsolidated Joint Venture Vitruvian Park [Member]

Unconsolidated Joint Venture Three [Member]

Unconsolidated Joint Venture Three [Member]

Unconsolidated Joint Venture Four Texas [Member]

Unconsolidated Joint Venture Four Texas [Member]

Unconsolidated Joint Venture Vitruvian Park [Member]

Unconsolidated Joint Venture Other MetLife [Member]

Unconsolidated Joint Venture Other MetLife [Member]

Participating Loan Investment Steele Creek Denver Colorado [Member]

Participating Loan Investment Steele Creek Denver Colorado [Member]

Participating Loan Investment Steele Creek Denver Colorado [Member]

Participating Loan Investment Steele Creek Denver Colorado [Member]

Unconsolidated Joint Venture UDR Met Life I Partnership [Member]

Unconsolidated Joint Venture UDR Met Life I Partnership [Member]

Unconsolidated Joint Venture UDR MetLife II Partnership [Member]

Unconsolidated Joint Venture Vitruvian Park [Member]

Unconsolidated Joint Venture Other MetLife [Member]

Apartment_Homes

Communities

Communities

Apartment_Homes

Apartment_Homes

Apartment_Homes

Apartment_Homes

Apartment_Homes

Land_Parcels

Land_Parcels

Communities

Communities

Apartment_Homes

Communities

Communities

Communities

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

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Joint_Ventures_Details_Textual

Joint Ventures (Details Textual) (USD $)

3 Months Ended

9 Months Ended

12 Months Ended

9 Months Ended

1 Months Ended

3 Months Ended

9 Months Ended

9 Months Ended

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Dec. 31, 2013

Dec. 31, 2012

Jan. 31, 2014

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Jan. 31, 2014

Dec. 31, 2013

Jul. 31, 2014

Sep. 30, 2014

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Mar. 31, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Sep. 30, 2014

Dec. 31, 2013

Communities

Communities

Unconsolidated Joint Venture Two Stoughton Massachusetts [Member]

Unconsolidated Joint Venture Two Stoughton Massachusetts [Member]

Unconsolidated Joint Venture Five San Diego California [Member]

Unconsolidated Joint Venture Five San Diego California [Member]

13th & Market [Member]

Unconsolidated Joint Venture 399 Fremont [Member]

MetLife Swap [Member]

MetLife Swap [Member]

MetLife Swap [Member]

MetLife Swap [Member]

Land [Member]

Land [Member]

Land [Member]

Land [Member]

Land [Member]

Land [Member]

Operating Community [Member]

Operating Community [Member]

Operating Community [Member]

Operating Community [Member]

Operating Community [Member]

Operating Community [Member]

Operating Community [Member]

Operating Community [Member]

Operating Community [Member]

Operating Community [Member]

Operating Community [Member]

Operating Community [Member]

Development Community [Member]

Development Community [Member]

Development Community [Member]

Unconsolidated Joint Venture Vitruvian Park [Member]

Unconsolidated Joint Venture UDR Met Life I Partnership [Member]

Unconsolidated Joint Venture UDR Met Life I Partnership [Member]

Unconsolidated Joint Venture UDR MetLife II Partnership [Member]

Noncontrolling Interest [Member]

Unconsolidated Joint Venture Other MetLife [Member]

Unconsolidated Joint Venture Vitruvian Park [Member]

Unconsolidated Joint Venture Vitruvian Park [Member]

Unconsolidated Joint Venture UDR Met Life I Partnership [Member]

Unconsolidated Joint Venture UDR Met Life I Partnership [Member]

Unconsolidated Joint Venture UDR Met Life I Partnership [Member]

Unconsolidated Joint Venture UDR MetLife II Partnership [Member]

Unconsolidated Joint Venture UDR MetLife II Partnership [Member]

Unconsolidated Joint Venture Three Washington DC [Member]

Unconsolidated Joint Venture Three Washington DC [Member]

Unconsolidated Joint Venture Four Texas [Member]

Unconsolidated Joint Venture Four Texas [Member]

Unconsolidated Joint Venture Vitruvian Park [Member]

Unconsolidated Joint Venture Other MetLife [Member]

Unconsolidated Joint Venture Other MetLife [Member]

Land_Parcels

Land_Parcels

Communities

Communities

Communities

Communities

Communities

Communities

Communities

Communities

Schedule of Equity Method Investments [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Number of apartments of development community

'

'

'

'

'

'

'

'

'

'

'

'

0

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Communities Sold

'

'

6

0

2

'

'

'

'

'

'

'

'

'

'

2

'

'

'

'

'

'

'

1

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Proceeds from Sale of Property, Plant, and Equipment

'

'

$237,700,000

'

'

'

'

'

'

'

'

'

'

'

'

$3,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Joint Venture and Partnership Number of Operating Communities Owned

141

'

141

'

'

'

'

'

'

'

'

'

'

'

'

'

'

6

5

'

2

'

1,000

'

'

'

0

6

'

21

'

3

'

8

'

1

2,000

'

Number of extension options on loan

'

'

'

'

'

'

'

2

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Extension period of option on loan

'

'

'

'

'

'

'

'3 months

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Secured Debt

1,399,372,000

'

1,399,372,000

'

1,442,077,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Joint Ventures

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Ownership interest in joint venture

'

'

'

'

'

'

'

'

'

0.00%

5.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Ownership percentage, equity method investment

'

'

'

'

'

'

'

'

95.00%

'

'

'

'

'

50.00%

50.00%

12.00%

'

4.00%

4.00%

50.10%

49.90%

4.00%

'

50.00%

50.00%

0.00%

'

13.20%

50.00%

50.00%

30.00%

30.00%

20.00%

20.00%

'

51.00%

51.00%

Real Estate Owned Gross

8,428,291,000

'

8,428,291,000

'

8,207,977,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Unamortized discount

8,000,000

'

8,000,000

'

11,800,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

First installment of payable incurred in partial consideration for acquisition of ownership interest in joint venture

37,835,000

'

37,835,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Second installment of payable incurred in partial consideration for acquisition of ownership interest in joint venture

521,233,000

'

521,233,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Interest expense

-33,087,000

-30,939,000

-97,662,000

-92,723,000

'

-92,723,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Company's equity investment in joint venture

650,441,000

'

650,441,000

'

507,655,000

'

'

'

'

'

'

'

'

'

'

'

'

'

5,364,000

7,161,000

'

'

'

'

79,807,000

79,318,000

0

'

40,336,000

436,805,000

327,926,000

22,891,000

25,919,000

-25,624,000

-23,591,000

'

87,376,000

36,313,000

Non-controlling interest held in joint venture

'

'

'

'

'

'

'

'

'

95.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Deferred profit from the sale of properties

27,132,000

'

27,132,000

'

25,400,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Management fees for our involvement in the joint ventures

2,700,000

2,800,000

8,300,000

8,500,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Cash Paid in Equity Method Investment Exchange

'

'

'

'

'

'

'

'

'

'

'

'

'

21,500,000

82,500,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Property, Plant and Equipment, Additions

'

'

129,400,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Debt associated with Real estate acquired

63,600,000

'

63,600,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, High

'

'

'

'

'

'

$4,000,000

'

'

'

'

$2,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Secured_and_Unsecured_Debt_Det

Secured and Unsecured Debt (Details) (USD $)	3 Months Ended	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2014	Dec. 31, 2013
Secured debt instruments	'	'	'
Weighted average interest rate	3.98%	'	'
Long-term Debt	$3,628,192	$3,628,192	$3,523,703
Unsecured Debt	2,228,820	2,228,820	2,081,626
Weighted Average Years to Maturity	'	'4 years 6 months	'
Line of Credit Facility, Amount Outstanding	2,200	2,200	'
Fixed Rate Debt [Member]	'	'	'
Secured debt instruments	'	'	'
Principal outstanding	1,061,926	1,061,926	1,072,373
Weighted average interest rate	5.19%	'	'
Weighted Average Years to Maturity	'	'3 years 2 months 29 days	'
Number of Communities Encumbered	30	'	'
Variable Rate Debt [Member]	'	'	'
Secured debt instruments	'	'	'
Principal outstanding	337,446	337,446	369,704
Weighted average interest rate	1.39%	'	'
Weighted Average Years to Maturity	'	'6 years 2 months 17 days	'
Number of Communities Encumbered	10	'	'
Mortgages Notes Payable [Member] | Fixed Rate Debt [Member]	'	'	'
Secured debt instruments	'	'	'
Principal outstanding	438,172	438,172	445,706
Weighted average interest rate	5.47%	'	'
Weighted Average Years to Maturity	'	'1 year 9 months 3 days	'
Number of Communities Encumbered	8	'	'
Mortgages Notes Payable [Member] | Variable Rate Debt [Member]	'	'	'
Secured debt instruments	'	'	'
Principal outstanding	31,337	31,337	63,595
Weighted average interest rate	1.94%	'	'
Weighted Average Years to Maturity	'	'2 years 3 months 25 days	'
Number of Communities Encumbered	1	'	'
Tax-exempt secured notes payable [Member] | Variable Rate Debt [Member]	'	'	'
Secured debt instruments	'	'	'
Principal outstanding	94,700	94,700	94,700
Weighted average interest rate	0.77%	'	'
Weighted Average Years to Maturity	'	'8 years 5 months 8 days	'
Number of Communities Encumbered	2	'	'
Fannie Mae credit facilities [Member] | Fixed Rate Debt [Member]	'	'	'
Secured debt instruments	'	'	'
Principal outstanding	'	'	626,667
Debt, Weighted Average Interest Rate	4.99%	4.99%	'
Weighted Average Years to Maturity	'	'4 years 3 months 7 days	'
Number of Communities Encumbered	22	'	'
Fannie Mae credit facilities [Member] | Variable Rate Debt [Member]	'	'	'
Secured debt instruments	'	'	'
Principal outstanding	211,409	211,409	211,409
Debt Instrument, Interest Rate at Period End	1.58%	1.58%	'
Weighted Average Years to Maturity	'	'5 years 9 months 7 days	'
Number of Communities Encumbered	7	'	'
Secured Debt [Member]	'	'	'
Secured debt instruments	'	'	'
Principal outstanding	1,399,372	1,399,372	1,442,077
Weighted average interest rate	4.27%	'	'
Long-term Debt	1,399,372	1,399,372	'
Weighted Average Years to Maturity	'	'3 years 11 months 12 days	'
Number of Communities Encumbered	40	'	'
Secured Debt [Member] | Fixed Rate Debt [Member]	'	'	'
Secured debt instruments	'	'	'
Long-term Debt	1,061,926	1,061,926	'
Secured Debt [Member] | Variable Rate Debt [Member]	'	'	'
Secured debt instruments	'	'	'
Long-term Debt	337,446	337,446	'
Unsecured Revolving Credit Facility due October 2015 [Member]	'	'	'
Secured debt instruments	'	'	'
Weighted average interest rate	1.10%	'	'
Weighted Average Years to Maturity	'	'3 years 2 months 4 days	'
Line of Credit Facility, Amount Outstanding	160,000	160,000	0
ThreePointSevenTermNotesDueOctober2020 [Member]	'	'	'
Secured debt instruments	'	'	'
Weighted average interest rate	'	3.70%	'
Senior Notes	299,952	299,952	299,946
Weighted Average Years to Maturity	'	'6 years	'
Four Point Six Three Percent Term Medium Notes Due January Two Thousand Twenty-Two [Member]	'	'	'
Secured debt instruments	'	'	'
Weighted average interest rate	4.63%	'	'
Senior Notes	397,387	397,387	397,118
Weighted Average Years to Maturity	'	'7 years 3 months 10 days	'
3.75 MTN Due July 2024 [Member]	'	'	'
Secured debt instruments	'	'	'
Weighted average interest rate	3.75%	'	'
Senior Notes	298,983	298,983	0
Weighted Average Years to Maturity	'	'9 years 9 months	'
1.67% Term Notes due December 2016 [Member]	'	'	'
Secured debt instruments	'	'	'
Weighted average interest rate	1.30%	'	'
Senior Notes	35,000	35,000	35,000
Weighted Average Years to Maturity	'	'3 years 8 months 4 days	'
2.68% Term Notes due December 2016 [Member]	'	'	'
Secured debt instruments	'	'	'
Weighted average interest rate	1.53%	'	'
Senior Notes	100,000	100,000	65,000
Weighted Average Years to Maturity	'	'3 years 8 months 4 days	'
Six Point Zero Five Percent, Medium Term Notes, Due June 2013 [Member]	'	'	'
Secured debt instruments	'	'	'
Weighted Average Years to Maturity	'	'0 months 0 days	'
Five Point One Three Percent, Medium Term Notes, Due January 2014 [Member]	'	'	'
Secured debt instruments	'	'	'
Weighted average interest rate	0.00%	'	'
Senior Notes	0	0	184,000
Weighted Average Years to Maturity	'	'0 days	'
Five Point Five Zero Percent, Medium Term Notes, Due April 2014 [Member]	'	'	'
Secured debt instruments	'	'	'
Weighted average interest rate	0.00%	'	'
Senior Notes	0	0	128,480
Weighted Average Years to Maturity	'	'0 months	'
Five Point Two Five Percent, Medium Term Notes, Due January 2015 [Member]	'	'	'
Secured debt instruments	'	'	'
Weighted average interest rate	5.25%	'	'
Senior Notes	325,138	325,138	325,041
Weighted Average Years to Maturity	'	'3 months 14 days	'
Five Point Two Five Percent, Medium Term Notes, Due January 2016 [Member]	'	'	'
Secured debt instruments	'	'	'
Weighted average interest rate	5.25%	'	'
Senior Notes	83,260	83,260	83,260
Weighted Average Years to Maturity	'	'1 year 6 months 14 days	'
2.90% Term Notes due January 2016 [Member]	'	'	'
Secured debt instruments	'	'	'
Weighted average interest rate	2.17%	'	'
Senior Notes	215,000	215,000	250,000
Weighted Average Years to Maturity	'	'3 years 8 months 4 days	'
Eight Point Five Zero Percent, Debentures, Due September 2024 [Member]	'	'	'
Secured debt instruments	'	'	'
Weighted average interest rate	8.50%	'	'
Senior Notes	15,644	15,644	15,644
Weighted Average Years to Maturity	'	'9 years 11 months 15 days	'
Four Point Two Five Percentage Medium-Term Notes due June 2018 [Member]	'	'	'
Secured debt instruments	'	'	'
Weighted average interest rate	4.25%	'	'
Senior Notes	298,428	298,428	298,107
Weighted Average Years to Maturity	'	'3 years 8 months 1 day	'
Other [Member]	'	'	'
Secured debt instruments	'	'	'
Senior Notes	28	28	30
Unsecured Debt [Member]	'	'	'
Secured debt instruments	'	'	'
Weighted average interest rate	3.80%	'	'
Long-term Debt	2,228,820	2,228,820	'
Unsecured Debt	2,228,820	2,228,820	2,081,626
Weighted Average Years to Maturity	'	'4 years 10 months 24 days	'
Fair Value, Measurements, Recurring [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member] | Mortgages Notes Payable [Member] | Fannie Mae credit facilities [Member] | Fixed Rate Debt [Member]	'	'	'
Secured debt instruments	'	'	'
Principal outstanding	623,754	623,754	'
Fair Value, Measurements, Recurring [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member] | Line of Credit [Member] | Fannie Mae credit facilities [Member] | Variable Rate Debt [Member]	'	'	'
Secured debt instruments	'	'	'
Principal outstanding	$211,409	$211,409	'

Secured_and_Unsecured_Debt_Det1

Secured and Unsecured Debt (Details 1) (USD $)	9 Months Ended	12 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2012	Dec. 31, 2013
Secured credit facilities	'	'	'
Borrowings outstanding	$2,200	'	'
Fannie Mae [Member]	'	'	'
Secured credit facilities	'	'	'
Borrowings outstanding	835,163	'	838,076
Weighted average daily borrowings during the period ended	836,305	839,597	'
Maximum daily borrowings during the period ended	$837,564	$841,494	'
Weighted average interest rate during the period ended	4.10%	4.20%	'
Interest rate at the end of the period	4.10%	'	4.10%

Secured_and_Unsecured_Debt_Det2

Secured and Unsecured Debt (Details 2) (USD $)

9 Months Ended

9 Months Ended

9 Months Ended

9 Months Ended

9 Months Ended

3 Months Ended

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Fixed Rate Debt [Member]

Variable Rate Debt [Member]

ThreePointSevenTermNotesDueOctober2020 [Member]

ThreePointSevenTermNotesDueOctober2020 [Member]

ThreePointSevenTermNotesDueOctober2020 [Member]

2.68% Term Notes due December 2016 [Member]

2.68% Term Notes due December 2016 [Member]

Four Point Six Three Percent Term Medium Notes Due January Two Thousand Twenty-Two [Member]

Four Point Six Three Percent Term Medium Notes Due January Two Thousand Twenty-Two [Member]

Mortgages Notes Payable [Member]

Mortgages Notes Payable [Member]

Tax Exempt Notes Payable [Member]

Fannie Mae credit facilities [Member]

Fannie Mae credit facilities [Member]

3.75 MTN Due July 2024 [Member]

UDR Bank Credit Facility [Member]

Fixed Rate Debt [Member]

Variable Rate Debt [Member]

Variable Rate Debt [Member]

Fixed Rate Debt [Member]

Variable Rate Debt [Member]

Debt Instrument [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Debt Instrument, Basis Spread on Variable Rate

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

1.10%

Debt Instrument Facility Fee, Basis Spread on Variable Rate

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

0.20%

Secured Debt, Encumbers Real Estate Owned, Amount

$2,300,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Secured Debt, Encumbers Real Estate Owned, Percent

26.90%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Debt Instrument Weighted Average Years to Maturity

'4 years 6 months

'

'3 years 2 months 29 days

'6 years 2 months 17 days

'6 years

'

'

'3 years 8 months 4 days

'

'7 years 3 months 10 days

'

'1 year 9 months 3 days

'2 years 3 months 25 days

'8 years 5 months 8 days

'4 years 3 months 7 days

'5 years 9 months 7 days

'9 years 9 months

'

Debt Instrument, Interest Rate, Stated Percentage

'

'

'

'

'

0.00%

3.70%

2.50%

2.68%

4.63%

4.63%

'

'

'

'

'

3.75%

'

Unamortized discount

8,000,000

11,800,000

'

'

'

'

'

'

'

2,792,000

2,882,000

'

'

'

'

'

1,000,000

'

Aggregate maturities of secured debt

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

2014

37,835,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

2015

521,233,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

2016

250,188,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

2017

402,955,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

2018

874,982,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Thereafter

1,540,999,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Total

1,399,372,000

1,442,077,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Secured Debt, Unencumbered Real Estate Owned, Amount

$6,100,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Secured Debt, Unencumbered Real Estate Owned, Percent

73.10%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Secured_and_Unsecured_Debt_Det3

Secured and Unsecured Debt (Details 3) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Summary of unsecured debt	'	'
Borrowings outstanding at end of period	$2,200	'
Unsecured Debt, Total	2,228,820	2,081,626
Unamortized discount	8,000	11,800
Borrowings outstanding under an unsecured credit facility due October 2015 [Member]	'	'
Summary of unsecured debt	'	'
Borrowings outstanding at end of period	160,000	0
4.63% Medium-Term Notes due January 2022 [Member]	'	'
Summary of unsecured debt	'	'
Senior Unsecured Notes	397,387	397,118
Fixed interest rate	4.63%	4.63%
Unamortized discount	2,792	2,882
1.67% Term Notes due December 2016 [Member]	'	'
Summary of unsecured debt	'	'
Senior Unsecured Notes	35,000	35,000
Fixed interest rate	1.30%	1.65%
2.68% Term Notes due December 2016 [Member]	'	'
Summary of unsecured debt	'	'
Senior Unsecured Notes	100,000	65,000
Fixed interest rate	2.50%	2.68%
6.05% Medium-Term Notes due June 2013 [Member]	'	'
Summary of unsecured debt	'	'
Fixed interest rate	6.05%	6.05%
5.13% Medium-Term Notes due January 2014 [Member]	'	'
Summary of unsecured debt	'	'
Senior Unsecured Notes	0	184,000
Fixed interest rate	5.13%	5.13%
5.50% Medium-Term Notes due April 2014 [Member]	'	'
Summary of unsecured debt	'	'
Senior Unsecured Notes	0	128,480
Fixed interest rate	5.50%	5.50%
Unamortized discount	3	20
5.25% Medium-Term Notes due January 2015 [Member]	'	'
Summary of unsecured debt	'	'
Senior Unsecured Notes	325,138	325,041
Fixed interest rate	5.25%	5.25%
Unamortized discount	102	134
5.25% Medium-Term Notes due January 2016 [Member]	'	'
Summary of unsecured debt	'	'
Senior Unsecured Notes	83,260	83,260
Fixed interest rate	5.25%	5.25%
2.90% Term Notes due January 2016 [Member]	'	'
Summary of unsecured debt	'	'
Senior Unsecured Notes	215,000	250,000
Fixed interest rate	2.73%	2.90%
8.50% Debentures due September 2024 [Member]	'	'
Summary of unsecured debt	'	'
Senior Unsecured Notes	15,644	15,644
Fixed interest rate	8.50%	8.50%
4.25% Medium-Term Notes due June 2018 [Member]	'	'
Summary of unsecured debt	'	'
Senior Unsecured Notes	298,428	298,107
Fixed interest rate	4.25%	4.25%
Unamortized discount	1,786	1,893
Other [Member]	'	'
Summary of unsecured debt	'	'
Senior Unsecured Notes	$28	$30

Secured_and_Unsecured_Debt_Det4

Secured and Unsecured Debt (Details 4) (USD $)	9 Months Ended	12 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2012	Dec. 31, 2013
Summary of short-term bank borrowings under unsecured commercial bank credit facility	'	'	'
Total revolving credit facility	$835,200	'	'
Borrowings outstanding at end of period	2,200	'	'
Unsecured Commercial Bank Credit Facility [Member]	'	'	'
Summary of short-term bank borrowings under unsecured commercial bank credit facility	'	'	'
Total revolving credit facility	900,000	'	900,000
Borrowings outstanding at end of period	160,000	'	0
Weighted average daily borrowings during the period ended	321,821	169,844	'
Maximum daily borrowings during the period ended	$625,000	$372,000	'
Weighted average interest rate during the period ended	1.20%	1.20%	'
Interest rate at the end of the period	1.10%	'	1.30%

Secured_and_Unsecured_Debt_Det5

Secured and Unsecured Debt (Details 5) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Aggregate maturities of unsecured debt	'	'
2014	$37,835	'
2015	521,233	'
2016	250,188	'
2017	402,955	'
2018	874,982	'
Thereafter	1,540,999	'
Unsecured Debt, Total	2,228,820	2,081,626
Long-term Debt	3,628,192	3,523,703
Secured Debt [Member]	'	'
Aggregate maturities of unsecured debt	'	'
2014	37,835	'
2015	197,359	'
2016	167,771	'
2017	242,955	'
2018	226,472	'
Thereafter	526,980	'
Long-term Debt	1,399,372	'
Unsecured Debt [Member]	'	'
Aggregate maturities of unsecured debt	'	'
2014	0	'
2015	323,874	'
2016	82,417	'
2017	160,000	'
2018	648,510	'
Thereafter	1,014,019	'
Unsecured Debt, Total	2,228,820	2,081,626
Long-term Debt	2,228,820	'
Fixed Rate Debt [Member] | Secured Debt [Member]	'	'
Aggregate maturities of unsecured debt	'	'
2014	37,835	'
2015	197,359	'
2016	136,434	'
2017	177,955	'
2018	176,472	'
Thereafter	335,871	'
Long-term Debt	1,061,926	'
Variable Rate Debt [Member] | Secured Debt [Member]	'	'
Aggregate maturities of unsecured debt	'	'
2014	0	'
2015	0	'
2016	31,337	'
2017	65,000	'
2018	50,000	'
Thereafter	191,109	'
Long-term Debt	$337,446	'

Secured_and_Unsecured_Debt_Det6

Secured and Unsecured Debt (Details Textual) (USD $)

3 Months Ended

3 Months Ended

3 Months Ended

3 Months Ended

3 Months Ended

9 Months Ended

3 Months Ended

3 Months Ended

9 Months Ended

3 Months Ended

9 Months Ended

3 Months Ended

9 Months Ended

9 Months Ended

12 Months Ended

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Jun. 26, 2014

Sep. 30, 2014

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Dec. 31, 2012

Fixed Rate Debt [Member]

Fixed Rate Debt [Member]

Variable Rate Debt [Member]

Variable Rate Debt [Member]

3.75 MTN Due July 2024 [Member]

3.75 MTN Due July 2024 [Member]

Mortgages Notes Payable [Member]

Mortgages Notes Payable [Member]

Mortgages Notes Payable [Member]

Mortgages Notes Payable [Member]

Mortgages Notes Payable [Member]

Debt Assumed As Part of Acquisition [Member]

Debt Assumed As Part of Acquisition [Member]

Debt Assumed As Part of Acquisition [Member]

Debt Assumed As Part of Acquisition [Member]

Tax Exempt Notes Payable [Member]

Tax Exempt Notes Payable [Member]

Fannie Mae credit facilities [Member]

Fannie Mae credit facilities [Member]

Fannie Mae credit facilities [Member]

Fannie Mae credit facilities [Member]

Tax Exempt Secured Notes Payable [Member]

Tax Exempt Secured Notes Payable [Member]

UDR Bank Credit Facility [Member]

UDR Bank Credit Facility [Member]

Line of Credit [Member]

Mortgages Notes Payable [Member]

End of range of inital term of debt [Member]

End of range of inital term of debt [Member]

Fixed Rate Debt [Member]

Fixed Rate Debt [Member]

Fixed Rate Debt [Member]

Variable Rate Debt [Member]

Variable Rate Debt [Member]

Variable Rate Debt [Member]

Variable Rate Debt [Member]

Fixed Rate Debt [Member]

Fixed Rate Debt [Member]

Variable Rate Debt [Member]

Variable Rate Debt [Member]

Variable Rate Debt [Member]

Variable Rate Debt [Member]

Carrying (Reported) Amount, Fair Value Disclosure [Member]

Carrying (Reported) Amount, Fair Value Disclosure [Member]

Fannie Mae credit facilities [Member]

Fannie Mae credit facilities [Member]

credit_facility

Fair Value, Measurements, Recurring [Member]

Fair Value, Measurements, Recurring [Member]

Fannie Mae credit facilities [Member]

Fannie Mae credit facilities [Member]

Variable Rate Debt [Member]

Fixed Rate Debt [Member]

Debt Instrument [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Medium-term Notes

'

'

'

'

'

'

'

$300,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Debt Instrument, Interest Rate, Stated Percentage

'

'

'

'

'

'

3.75%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Percentage of Debt Instrument Price

'

'

'

'

'

'

99.65%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Secured Debt (Textual) [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Secured debt amount which encumbers real estate owned based upon book value

2,300,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Percentage of secured debt which encumbers real estate owned based upon book value

26.90%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Secured debt amount of real estate owned which is unencumbered

6,100,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Percentage of secured debt of real estate owned which is unencumbered

73.10%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Number of secured credit facilities

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

3

'

'

'

'

'

'

'

'

'

'

'

Credit facilities with aggregate commitment

835,200,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

835,200,000

'

'

'

'

'

900,000,000

900,000,000

'

'

'

'

Debt Instrument, Term

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'10 years

'10 years

Secured debt including debt on real estate held for sale

'

'

1,061,926,000

1,072,373,000

337,446,000

369,704,000

'

'

438,172,000

438,172,000

445,706,000

31,337,000

63,595,000

'

'

'

'

94,700,000

94,700,000

'

626,667,000

211,409,000

211,409,000

'

'

'

'

211,409,000

623,754,000

'

'

Weighted average interest rate

3.98%

'

5.19%

'

1.39%

'

3.75%

'

5.47%

'

'

1.94%

'

'

'

'

'

0.77%

'

'

'

'

'

'

'

'

'

'

'

'

'

Unamortized fair market adjustment

8,000,000

11,800,000

'

'

'

'

1,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Debt Instrument, Maturity Date Range, Start

'

'

'

'

'

'

'

'

'

1-Dec-14

'

'

'

'

'

'

'

'

'

1-May-17

'

'

'

1-Aug-19

'

'

'

'

'

'

'

Debt instrument, maturity date range, end

'

'

'

'

'

'

'

'

'

1-May-19

'

'

'

'

'

'

'

'

'

1-Jul-23

'

'

'

20-Mar-32

'

'

'

'

'

'

'

Notes payable minimum interest rates range

'

'

'

'

'

'

'

'

'

3.43%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

0.74%

'

'

'

'

'

'

Notes payable maximum interest rates range

'

'

'

'

'

'

'

'

'

5.94%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

0.79%

'

'

'

'

'

'

Amortization of Debt Discount (Premium)

'

'

'

'

'

'

'

'

'

'

'

'

'

$1,300,000

$1,300,000

$3,800,000

$3,800,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Secured_and_Unsecured_Debt_Det7

Secured and Unsecured Debt (Details Textual 1) (USD $)

1 Months Ended

3 Months Ended

3 Months Ended

0 Months Ended

9 Months Ended

3 Months Ended

12 Months Ended

3 Months Ended

3 Months Ended

3 Months Ended

12 Months Ended

3 Months Ended

Jun. 30, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 26, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2013

Sep. 30, 2014

Dec. 31, 2012

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Dec. 31, 2012

Sep. 30, 2014

Five Point Five Zero Percent, Medium Term Notes, Due April 2014 [Member]

Five Point Five Zero Percent, Medium Term Notes, Due April 2014 [Member]

ThreePointSevenTermNotesDueOctober2020 [Member]

ThreePointSevenTermNotesDueOctober2020 [Member]

ThreePointSevenTermNotesDueOctober2020 [Member]

ThreePointSevenTermNotesDueOctober2020 [Member]

1.67% Term Notes due December 2016 [Member]

1.67% Term Notes due December 2016 [Member]

1.67% Term Notes due December 2016 [Member]

2.90% Term Notes due January 2016 [Member]

2.90% Term Notes due January 2016 [Member]

4.63% Medium-Term Notes due January 2022 [Member]

4.63% Medium-Term Notes due January 2022 [Member]

2.68% Term Notes due December 2016 [Member]

2.68% Term Notes due December 2016 [Member]

UDR Bank Credit Facility [Member]

UDR Bank Credit Facility [Member]

Beginning of range of initial term of debt [Member]

Fannie Mae [Member]

Line of Credit [Member]

Unsecured Debt (Textual) [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Total revolving credit facility

'

$835,200,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$900,000,000

$900,000,000

'

'

Increase in maximum borrowing capacity of unsecured revolving credit facility

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

1,450,000,000

'

'

'

Credit facility interest rate

'100

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Line of Credit Facility, Commitment Fee Description

'15

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Fixed interest rate

'

'

'

5.50%

5.50%

'

'

0.00%

3.70%

1.30%

'

1.65%

2.73%

2.90%

4.63%

4.63%

2.50%

2.68%

'

'

'

'

Interest rate

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

1.10%

1.30%

'

'

Line of Credit Facility, Amount Outstanding

'

2,200,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

160,000,000

0

'

'

Debt Instrument, Maturity Date

'

'

'

'

'

31-Oct-20

'

'

'

'

1-Jun-18

'

'

'

'

'

'

'

'

'

'

'

Unamortized discount

'

8,000,000

11,800,000

3,000

20,000

'

'

'

'

'

'

'

'

'

2,792,000

2,882,000

'

'

'

'

'

'

Senior Notes

'

'

'

$0

$128,480,000

'

$299,952,000

$299,946,000

'

$35,000,000

'

$35,000,000

$215,000,000

$250,000,000

$397,387,000

$397,118,000

$100,000,000

$65,000,000

'

'

'

'

Debt Instrument, Interest Rate During Period

'

3.98%

'

0.00%

'

'

3.70%

'

'

1.30%

'

'

2.17%

'

4.63%

'

1.53%

'

'

'

'

'

Debt Instrument, Term

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'7 years

'10 years

Debt_UNITED_DOMINION_REALTY_LP2

Debt (UNITED DOMINION REALTY, L.P.) (Details) (USD $)

3 Months Ended

3 Months Ended

3 Months Ended

3 Months Ended

3 Months Ended

3 Months Ended

3 Months Ended

9 Months Ended

9 Months Ended

9 Months Ended

9 Months Ended

9 Months Ended

In Thousands, unless otherwise specified

Sep. 30, 2014

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Fixed Rate Debt [Member]

Fixed Rate Debt [Member]

Fixed Rate Debt [Member]

Fixed Rate Debt [Member]

Fixed Rate Debt [Member]

Fixed Rate Debt [Member]

Variable Rate Debt [Member]

Variable Rate Debt [Member]

Variable Rate Debt [Member]

Variable Rate Debt [Member]

Variable Rate Debt [Member]

Variable Rate Debt [Member]

Variable Rate Debt [Member]

Variable Rate Debt [Member]

United Dominion Reality L.P. [Member]

United Dominion Reality L.P. [Member]

United Dominion Reality L.P. [Member]

United Dominion Reality L.P. [Member]

United Dominion Reality L.P. [Member]

United Dominion Reality L.P. [Member]

United Dominion Reality L.P. [Member]

United Dominion Reality L.P. [Member]

United Dominion Reality L.P. [Member]

United Dominion Reality L.P. [Member]

United Dominion Reality L.P. [Member]

United Dominion Reality L.P. [Member]

Line of Credit [Member]

Line of Credit [Member]

Line of Credit [Member]

Line of Credit [Member]

Line of Credit [Member]

Communities

Mortgages Notes Payable [Member]

Mortgages Notes Payable [Member]

Fannie Mae credit facilities [Member]

Fannie Mae credit facilities [Member]

Communities

Mortgages Notes Payable [Member]

Mortgages Notes Payable [Member]

Fannie Mae credit facilities [Member]

Fannie Mae credit facilities [Member]

Tax Exempt Notes Payable [Member]

Tax Exempt Notes Payable [Member]

Communities

Fixed Rate Debt [Member]

Fixed Rate Debt [Member]

Fixed Rate Debt [Member]

Fixed Rate Debt [Member]

Fixed Rate Debt [Member]

Variable Rate Debt [Member]

Variable Rate Debt [Member]

Variable Rate Debt [Member]

Variable Rate Debt [Member]

Variable Rate Debt [Member]

Carrying (Reported) Amount, Fair Value Disclosure [Member]

Carrying (Reported) Amount, Fair Value Disclosure [Member]

Carrying (Reported) Amount, Fair Value Disclosure [Member]

Carrying (Reported) Amount, Fair Value Disclosure [Member]

Carrying (Reported) Amount, Fair Value Disclosure [Member]

Communities

Communities

Communities

Communities

Communities

Communities

Mortgages Notes Payable [Member]

Mortgages Notes Payable [Member]

Fannie Mae credit facilities [Member]

Communities

Fannie Mae credit facilities [Member]

Tax Exempt Notes Payable [Member]

Tax Exempt Notes Payable [Member]

Fair Value, Measurements, Recurring [Member]

Fair Value, Measurements, Recurring [Member]

Fair Value, Measurements, Recurring [Member]

Fair Value, Measurements, Recurring [Member]

Fair Value, Measurements, Recurring [Member]

Communities

Communities

Communities

Communities

Variable Rate Debt [Member]

United Dominion Reality L.P. [Member]

United Dominion Reality L.P. [Member]

United Dominion Reality L.P. [Member]

United Dominion Reality L.P. [Member]

Fannie Mae credit facilities [Member]

Fixed Rate Debt [Member]

Fixed Rate Debt [Member]

Variable Rate Debt [Member]

Variable Rate Debt [Member]

Fannie Mae credit facilities [Member]

Fannie Mae credit facilities [Member]

Fannie Mae credit facilities [Member]

Fannie Mae credit facilities [Member]

Debt Instrument [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Principal outstanding

'

$1,061,926

$1,072,373

$438,172

$445,706

'

$626,667

$337,446

$369,704

$31,337

$63,595

$211,409

$211,409

$94,700

$94,700

$928,273

$934,865

$759,215

$765,806

$380,506

$386,803

'

$169,058

$169,059

'

$27,000

$27,000

$211,409

$378,709

$379,003

$142,058

$142,059

Weighted average interest rate

3.98%

5.19%

'

5.47%

'

'

'

1.39%

'

1.94%

'

'

'

0.77%

'

4.47%

'

5.09%

'

5.46%

'

'

1.70%

'

'

'

'

'

'

'

'

'

Number of Communities Encumbered (in communities)

'

30

'

8

'

22

'

10

'

1

'

7

'

2

'

21

'

15

'

5

'

10

6

'

5

1

'

'

'

'

'

'

Debt, Weighted Average Interest Rate

'

'

'

'

'

4.99%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

4.71%

'

'

1.88%

'

'

'

'

'

'

'

Debt Instrument, Interest Rate at Period End

'

'

'

'

'

'

'

'

'

'

'

1.58%

'

'

'

'

'

'

'

'

'

'

'

'

'

0.74%

'

'

'

'

'

'

Debt_UNITED_DOMINION_REALTY_LP3

Debt (UNITED DOMINION REALTY, L.P.) (Details 1) (USD $)	9 Months Ended	12 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2012	Dec. 31, 2013
Debt Instrument [Line Items]	'	'	'
Debt Instrument Weighted Average Years to Maturity	'4 years 6 months	'	'
Borrowings outstanding	$2,200	'	'
Fannie Mae [Member]	'	'	'
Debt Instrument [Line Items]	'	'	'
Borrowings outstanding	835,163	'	838,076
Weighted average daily borrowings during the period ended	836,305	839,597	'
Maximum daily borrowings during the period ended	837,564	841,494	'
Weighted average interest rate during the period ended	4.10%	4.20%	'
Interest rate at the end of the period	4.10%	'	4.10%
United Dominion Reality L.P. [Member]	'	'	'
Debt Instrument [Line Items]	'	'	'
Debt Instrument Weighted Average Years to Maturity	'4 years 3 months 3 days	'	'
United Dominion Reality L.P. [Member] | Fannie Mae [Member]	'	'	'
Debt Instrument [Line Items]	'	'	'
Borrowings outstanding	520,768	'	521,062
Weighted average daily borrowings during the period ended	521,480	522,007	'
Maximum daily borrowings during the period ended	$522,265	$523,187	'
Weighted average interest rate during the period ended	3.90%	4.20%	'
Interest rate at the end of the period	3.90%	'	4.10%
Fixed Rate Debt [Member]	'	'	'
Debt Instrument [Line Items]	'	'	'
Debt Instrument Weighted Average Years to Maturity	'3 years 2 months 29 days	'	'
Fixed Rate Debt [Member] | Mortgages [Member]	'	'	'
Debt Instrument [Line Items]	'	'	'
Debt Instrument Weighted Average Years to Maturity	'1 year 9 months 3 days	'	'
Fixed Rate Debt [Member] | Line of Credit [Member]	'	'	'
Debt Instrument [Line Items]	'	'	'
Debt Instrument Weighted Average Years to Maturity	'4 years 3 months 7 days	'	'
Fixed Rate Debt [Member] | United Dominion Reality L.P. [Member]	'	'	'
Debt Instrument [Line Items]	'	'	'
Debt Instrument Weighted Average Years to Maturity	'3 years 4 months 4 days	'	'
Fixed Rate Debt [Member] | United Dominion Reality L.P. [Member] | Mortgages [Member]	'	'	'
Debt Instrument [Line Items]	'	'	'
Debt Instrument Weighted Average Years to Maturity	'1 year 9 months 29 days	'	'
Fixed Rate Debt [Member] | United Dominion Reality L.P. [Member] | Line of Credit [Member]	'	'	'
Debt Instrument [Line Items]	'	'	'
Debt Instrument Weighted Average Years to Maturity	'4 years 8 months 26 days	'	'
Variable Rate Debt [Member]	'	'	'
Debt Instrument [Line Items]	'	'	'
Debt Instrument Weighted Average Years to Maturity	'6 years 2 months 17 days	'	'
Variable Rate Debt [Member] | Mortgages [Member]	'	'	'
Debt Instrument [Line Items]	'	'	'
Debt Instrument Weighted Average Years to Maturity	'2 years 3 months 25 days	'	'
Variable Rate Debt [Member] | Tax Exempt Notes Payable [Member]	'	'	'
Debt Instrument [Line Items]	'	'	'
Debt Instrument Weighted Average Years to Maturity	'8 years 5 months 8 days	'	'
Variable Rate Debt [Member] | Line of Credit [Member]	'	'	'
Debt Instrument [Line Items]	'	'	'
Debt Instrument Weighted Average Years to Maturity	'5 years 9 months 7 days	'	'
Variable Rate Debt [Member] | United Dominion Reality L.P. [Member]	'	'	'
Debt Instrument [Line Items]	'	'	'
Debt Instrument Weighted Average Years to Maturity	'8 years 8 months 4 days	'	'
Variable Rate Debt [Member] | United Dominion Reality L.P. [Member] | Mortgages [Member]	'	'	'
Debt Instrument [Line Items]	'	'	'
Debt Instrument Weighted Average Years to Maturity	'0 days	'	'
Variable Rate Debt [Member] | United Dominion Reality L.P. [Member] | Tax Exempt Notes Payable [Member]	'	'	'
Debt Instrument [Line Items]	'	'	'
Debt Instrument Weighted Average Years to Maturity	'17 years 5 months 19 days	'	'
Variable Rate Debt [Member] | United Dominion Reality L.P. [Member] | Line of Credit [Member]	'	'	'
Debt Instrument [Line Items]	'	'	'
Debt Instrument Weighted Average Years to Maturity	'6 years 11 months 19 days	'	'

Debt_UNITED_DOMINION_REALTY_LP4

Debt (UNITED DOMINION REALTY, L.P.) (Details 2) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Debt Instrument [Line Items]	'	'
2014	$37,835	'
2015	521,233	'
2016	250,188	'
2017	402,955	'
2018	874,982	'
Thereafter	1,540,999	'
Total	1,399,372	1,442,077
United Dominion Reality L.P. [Member]	'	'
Debt Instrument [Line Items]	'	'
2014	2,223	'
2015	193,441	'
2016	132,331	'
2017	23,836	'
2018	209,711	'
Thereafter	366,731	'
Total	928,273	934,865
United Dominion Reality L.P. [Member] | Mortgages Notes Payable [Member] | Fixed Rate Debt [Member]	'	'
Debt Instrument [Line Items]	'	'
2014	2,134	'
2015	193,075	'
2016	131,946	'
2017	1,630	'
2018	1,685	'
Thereafter	50,036	'
Total	380,506	'
United Dominion Reality L.P. [Member] | Fannie Mae credit facilities [Member] | Fixed Rate Debt [Member]	'	'
Debt Instrument [Line Items]	'	'
2014	89	'
2015	366	'
2016	385	'
2017	15,640	'
2018	161,754	'
Thereafter	200,475	'
Total	378,709	'
United Dominion Reality L.P. [Member] | Fannie Mae credit facilities [Member] | Variable Rate Debt [Member]	'	'
Debt Instrument [Line Items]	'	'
2014	0	'
2015	0	'
2016	0	'
2017	6,566	'
2018	46,272	'
Thereafter	89,220	'
Total	142,058	'
United Dominion Reality L.P. [Member] | Tax Exempt Notes Payable [Member] | Variable Rate Debt [Member]	'	'
Debt Instrument [Line Items]	'	'
2014	0	'
2015	0	'
2016	0	'
2017	0	'
2018	0	'
Thereafter	27,000	'
Total	$27,000	'

Debt_UNITED_DOMINION_REALTY_LP5

Debt (UNITED DOMINION REALTY, L.P.) (Details Textual) (USD $)

3 Months Ended

3 Months Ended

3 Months Ended

9 Months Ended

3 Months Ended

9 Months Ended

3 Months Ended

3 Months Ended

3 Months Ended

3 Months Ended

0 Months Ended

9 Months Ended

3 Months Ended

0 Months Ended

3 Months Ended

9 Months Ended

9 Months Ended

9 Months Ended

3 Months Ended

9 Months Ended

9 Months Ended

9 Months Ended

9 Months Ended

9 Months Ended

12 Months Ended

9 Months Ended

12 Months Ended

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Dec. 31, 2013

Sep. 26, 2013

Sep. 30, 2014

Sep. 30, 2014

Dec. 31, 2013

Jun. 27, 2014

Sep. 30, 2014

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Dec. 31, 2012

Sep. 30, 2014

Dec. 31, 2012

UDR Bank Credit Facility [Member]

UDR Bank Credit Facility [Member]

Fixed Rate Debt [Member]

Fixed Rate Debt [Member]

Fannie Mae [Member]

Variable Rate Debt [Member]

Variable Rate Debt [Member]

Fannie Mae credit facilities [Member]

Fannie Mae credit facilities [Member]

Fannie Mae credit facilities [Member]

Fannie Mae credit facilities [Member]

Mortgages [Member]

Mortgages [Member]

Mortgages [Member]

Mortgages [Member]

Mortgages [Member]

Tax Exempt Notes Payable [Member]

Tax Exempt Notes Payable [Member]

Unsecured Revolving Credit Facility due October 2015 [Member]

Unsecured Revolving Credit Facility due October 2015 [Member]

2.90% Term Notes due January 2016 [Member]

Five Point Two Five Percent, Medium Term Notes, Due January 2016 [Member]

4.25% Medium-Term Notes due June 2018 [Member]

4.25% Medium-Term Notes due June 2018 [Member]

ThreePointSevenTermNotesDueOctober2020 [Member]

ThreePointSevenTermNotesDueOctober2020 [Member]

4.63% Medium-Term Notes due January 2022 [Member]

4.63% Medium-Term Notes due January 2022 [Member]

3.75 MTN Due July 2024 [Member]

3.75 MTN Due July 2024 [Member]

United Dominion Reality L.P. [Member]

United Dominion Reality L.P. [Member]

United Dominion Reality L.P. [Member]

United Dominion Reality L.P. [Member]

United Dominion Reality L.P. [Member]

United Dominion Reality L.P. [Member]

United Dominion Reality L.P. [Member]

United Dominion Reality L.P. [Member]

United Dominion Reality L.P. [Member]

United Dominion Reality L.P. [Member]

United Dominion Reality L.P. [Member]

United Dominion Reality L.P. [Member]

United Dominion Reality L.P. [Member]

United Dominion Reality L.P. [Member]

United Dominion Reality L.P. [Member]

United Dominion Reality L.P. [Member]

United Dominion Reality L.P. [Member]

United Dominion Reality L.P. [Member]

United Dominion Reality L.P. [Member]

United Dominion Reality L.P. [Member]

United Dominion Reality L.P. [Member]

United Dominion Reality L.P. [Member]

United Dominion Reality L.P. [Member]

United Dominion Reality L.P. [Member]

Mortgages [Member]

Mortgages [Member]

Mortgages [Member]

Mortgages [Member]

Mortgages [Member]

Mortgages [Member]

Mortgages [Member]

Mortgages [Member]

Mortgages [Member]

Line of Credit [Member]

Line of Credit [Member]

Line of Credit [Member]

Line of Credit [Member]

Line of Credit [Member]

Line of Credit [Member]

Line of Credit [Member]

Line of Credit [Member]

Line of Credit [Member]

Line of Credit [Member]

Line of Credit [Member]

Line of Credit [Member]

Line of Credit [Member]

Beginning of range of initial term of debt [Member]

End of range of inital term of debt [Member]

End of range of inital term of debt [Member]

Fixed Rate Debt [Member]

Fixed Rate Debt [Member]

Variable Rate Debt [Member]

Variable Rate Debt [Member]

Fixed Rate Debt [Member]

Fixed Rate Debt [Member]

Fixed Rate Debt [Member]

Variable Rate Debt [Member]

Variable Rate Debt [Member]

Variable Rate Debt [Member]

Variable Rate Debt [Member]

UDR Bank Credit Facility [Member]

Fixed Rate Debt [Member]

Fixed Rate Debt [Member]

Variable Rate Debt [Member]

Variable Rate Debt [Member]

Fannie Mae credit facilities [Member]

Fannie Mae credit facilities [Member]

Mortgages [Member]

Mortgages [Member]

Mortgages [Member]

Tax Exempt Notes Payable [Member]

Tax Exempt Notes Payable [Member]

2.90% Term Notes due January 2016 [Member]

2.90% Term Notes due January 2016 [Member]

1.68% Term Notes due December 2016 [Member]

Five Point Two Five Percent, Medium Term Notes, Due January 2016 [Member]

4.25% Medium-Term Notes due June 2018 [Member]

4.25% Medium-Term Notes due June 2018 [Member]

Three point seven percent medium term note due October 2020 [Member]

4.63% Medium-Term Notes due January 2022 [Member]

4.63% Medium-Term Notes due January 2022 [Member]

3.75 MTN Due July 2024 [Member]

Fair Value, Measurements, Recurring [Member]

Fair Value, Measurements, Recurring [Member]

Fair Value, Measurements, Recurring [Member]

Fair Value, Measurements, Recurring [Member]

Fair Value, Measurements, Recurring [Member]

Fair Value, Measurements, Recurring [Member]

Fair Value, Measurements, Recurring [Member]

Fair Value, Measurements, Recurring [Member]

Fair Value, Measurements, Recurring [Member]

Fair Value, Measurements, Recurring [Member]

Fair Value, Measurements, Recurring [Member]

Fair Value, Measurements, Recurring [Member]

Fair Value, Measurements, Recurring [Member]

Fair Value, Measurements, Recurring [Member]

Fair Value, Measurements, Recurring [Member]

Fair Value, Measurements, Recurring [Member]

Fair Value, Measurements, Recurring [Member]

Fair Value, Measurements, Recurring [Member]

Fair Value, Measurements, Recurring [Member]

Fair Value, Measurements, Recurring [Member]

Fair Value, Measurements, Recurring [Member]

Fair Value, Measurements, Recurring [Member]

Fannie Mae credit facilities [Member]

Fannie Mae credit facilities [Member]

Fannie Mae credit facilities [Member]

Financial Guarantee [Member]

Fixed Rate Debt [Member]

Variable Rate Debt [Member]

Fixed Rate Debt [Member]

Fixed Rate Debt [Member]

Fixed Rate Debt [Member]

Variable Rate Debt [Member]

Variable Rate Debt [Member]

Financial Guarantee [Member]

Financial Guarantee [Member]

Financial Guarantee [Member]

Financial Guarantee [Member]

Financial Guarantee [Member]

Financial Guarantee [Member]

United Dominion Reality L.P. [Member]

United Dominion Reality L.P. [Member]

Carrying (Reported) Amount, Fair Value Disclosure [Member]

Carrying (Reported) Amount, Fair Value Disclosure [Member]

Carrying (Reported) Amount, Fair Value Disclosure [Member]

Carrying (Reported) Amount, Fair Value Disclosure [Member]

Carrying (Reported) Amount, Fair Value Disclosure [Member]

United Dominion Reality L.P. [Member]

United Dominion Reality L.P. [Member]

Carrying (Reported) Amount, Fair Value Disclosure [Member]

Carrying (Reported) Amount, Fair Value Disclosure [Member]

Carrying (Reported) Amount, Fair Value Disclosure [Member]

Carrying (Reported) Amount, Fair Value Disclosure [Member]

Carrying (Reported) Amount, Fair Value Disclosure [Member]

Carrying (Reported) Amount, Fair Value Disclosure [Member]

Carrying (Reported) Amount, Fair Value Disclosure [Member]

Carrying (Reported) Amount, Fair Value Disclosure [Member]

Carrying (Reported) Amount, Fair Value Disclosure [Member]

Fannie Mae credit facilities [Member]

United Dominion Reality L.P. [Member]

United Dominion Reality L.P. [Member]

Fannie Mae credit facilities [Member]

United Dominion Reality L.P. [Member]

United Dominion Reality L.P. [Member]

United Dominion Reality L.P. [Member]

United Dominion Reality L.P. [Member]

United Dominion Reality L.P. [Member]

United Dominion Reality L.P. [Member]

Fixed Rate Debt [Member]

Variable Rate Debt [Member]

Fannie Mae credit facilities [Member]

Fannie Mae credit facilities [Member]

Fannie Mae credit facilities [Member]

Fannie Mae credit facilities [Member]

Fixed Rate Debt [Member]

Fixed Rate Debt [Member]

Variable Rate Debt [Member]

Variable Rate Debt [Member]

Debt Instrument [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Debt Instrument, Unamortized Premium

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$7,100,000

$10,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Variable Rate Secured Debt Instruments Fair Value

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

31,337,000

[1]

63,595,000

[1]

'

'

31,337,000

63,595,000

'

'

'

211,409,000

[1]

211,409,000

[1]

142,059,000

[2]

142,059,000

[2]

211,409,000

211,409,000

'

142,059,000

142,059,000

'

'

'

'

'

'

'

Debt Instrument, Maturity Date Range, Start

'

'

'

'

'

'

'

'

'

1-May-17

'

'

'

'

1-Dec-14

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

31-Dec-15

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Total revolving credit facility

835,200,000

'

900,000,000

900,000,000

'

'

'

'

'

835,200,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Borrowings outstanding

2,200,000

'

160,000,000

0

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

160,000,000

0

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Debt Instrument, Term

'

'

'

'

'

'

'10 years

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'7 years

'10 years

'10 years

Secured debt including debt on real estate held for sale

'

'

'

'

1,061,926,000

1,072,373,000

'

337,446,000

369,704,000

'

626,667,000

211,409,000

211,409,000

438,172,000

438,172,000

445,706,000

31,337,000

63,595,000

94,700,000

94,700,000

'

'

'

'

'

'

'

'

'

'

'

'

928,273,000

934,865,000

'

759,215,000

765,806,000

169,058,000

169,059,000

'

'

380,506,000

380,506,000

386,803,000

27,000,000

27,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

623,754,000

'

'

'

'

'

'

'

'

211,409,000

'

'

378,709,000

379,003,000

142,058,000

142,059,000

'

'

'

Weighted average interest rate

3.98%

'

'

'

5.19%

'

'

1.39%

'

'

'

'

'

5.47%

'

'

1.94%

'

0.77%

'

1.10%

'

2.17%

5.25%

4.25%

'

'

3.70%

4.63%

'

'

3.75%

4.47%

'

'

5.09%

'

1.70%

'

'

'

'

5.46%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Unamortized fair market adjustment

8,000,000

11,800,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

1,786,000

1,893,000

'

'

2,792,000

2,882,000

'

1,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Notes payable minimum interest rates range

'

'

'

'

'

'

'

'

'

'

'

'

'

'

3.43%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

3.43%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Notes payable maximum interest rates range

'

'

'

'

'

'

'

'

'

'

'

'

'

'

5.94%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

5.94%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Guarantor borrowing capacity

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

900,000,000

'

'

'

'

'

'

'

'

'

'

'

'

250,000,000

100,000,000

'

'

300,000,000

300,000,000

'

400,000,000

300,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Debt Instrument, Maturity Date Range, End

'

'

'

'

'

'

'

'

'

1-Jul-23

'

'

'

'

1-May-19

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

1-May-19

'

20-Mar-32

'

6-Jun-18

'

'

6-Jun-18

1-Jun-18

'

'

1-Jan-22

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Debt Instrument, Maturity Date

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

31-Oct-20

'

'

'

1-Jul-24

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Debt Instrument, Interest Rate at Period End

'

'

'

'

'

'

'

'

'

'

'

1.58%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

0.74%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Fixed Rate Secured Debt Instruments Fair Value

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$451,582,000

[1]

$466,375,000

[1]

$392,883,000

[2]

$403,695,000

[2]

$438,172,000

$445,706,000

'

$380,506,000

$386,803,000

$655,035,000

[1]

$661,094,000

[1]

$394,849,000

[2]

$394,239,000

[2]

$623,754,000

$626,667,000

'

$378,709,000

$379,003,000

'

'

'

'

'

'

'

Debt, Weighted Average Interest Rate

'

'

'

'

'

'

'

'

'

4.99%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

4.71%

1.88%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

[1]

See Note 2, Significant Accounting Policies

[2]

See Note 8, Derivatives and Hedging Activity

IncomeLoss_Per_Share_Details

Income/(Loss) Per Share (Details) (USD $)	3 Months Ended		9 Months Ended		12 Months Ended
In Thousands, except Share data, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2012
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]	'	'	'	'	'
Income/(loss) from continuing operations	$10,611	$2,351	$9,775	$5,713	'
Gains/(loss) on sales of real estate, net of tax	31,302	0	82,305	0	'
(Income)/loss from continuing operations attributable to noncontrolling interest	'	'	-3,167	'	'
Income/(loss) from continuing operations attributable to UDR, Inc.	40,476	2,336	88,911	'	5,637
Income/(loss) from continuing operations operations attributable to common stockholders	39,545	1,405	86,118	'	2,844
Income/(loss) from discontinued operations, net of tax	79	884	10	2,567	2,567
(Income)/loss from discontinued operations attributable to redeemable noncontrolling interest in the Operating Partnership	-6	-32	-4	'	-92
Income/(loss) from discontinued operations attributable to common stockholders	73	852	6	2,475	'
Net income/(loss)	41,992	3,235	92,090	8,280	'
Net (income)/loss attributable to noncontrolling interests	4	37	-2	30	'
Net (income)/loss attributable to redeemable non-controlling interests in Operating Partnership	1,447	84	3,171	198	198
Net (loss)/income attributable to common stockholders	39,618	2,257	86,124	5,319	5,319
Denominator for earnings per share - basic and diluted:	'	'	'	'	'
Weighted average common shares outstanding	252,891,000	250,744,000	251,860,000	'	250,663,000
Non-vested restricted stock rewards	1,236	759	-1,159	'	-701
Denominator for basic and diluted earnings per share	251,655,000	249,985,000	250,701,000	'	249,962,000
Incremental shares issuable for assumed conversion of: Stock options and unvested restricted stock	-2,077,000	-1,469,000	-1,974,000	'	-1,477,000
Weighted average number of common shares outstanding b diluted	253,732,000	251,454,000	252,675,000	251,439,000	251,439,000
Income/(loss) from continuing operations attributable to common stockholders, per basic share	$0.16	$0.01	$0.34	$0.01	'
Net income/(loss) attributable to common stockholders	$0.16	$0.01	$0.34	$0.02	'
Income/(loss) from discontinued operations attributable to common stockholders, per basic share	$0	$0	$0	$0.01	'
Income/(loss) from continuing operations attributable to common stockholders, per diluted share	$0.16	$0.01	$0.34	$0.01	'
Income from discontinued operations attributable to common stockholders, per diluted share	$0	$0	$0	$0.01	'
Net income/(loss) attributable to common stockholders	$0.16	$0.01	$0.34	$0.02	'
OP Units [Member]	'	'	'	'	'
Denominator for earnings per share - basic and diluted:	'	'	'	'	'
Antidilutive securities	9,188,987	9,323,373	9,274,401	'	9,342,522
Convertible preferred stock [Member]	'	'	'	'	'
Denominator for earnings per share - basic and diluted:	'	'	'	'	'
Antidilutive securities	3,035,548	3,035,548	3,035,548	'	3,035,548
Stock options and unvested restricted stock [Member]	'	'	'	'	'
Denominator for earnings per share - basic and diluted:	'	'	'	'	'
Antidilutive securities	2,077,297	1,468,706	1,974,025	'	1,477,021
Series E Preferred Stock [Member]	'	'	'	'	'
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]	'	'	'	'	'
Distributions to preferred stockholders - Series E (Convertible)	-931	-931	-2,793	-2,793	'
Noncontrolling Interests [Member]	'	'	'	'	'
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]	'	'	'	'	'
(Income)/loss from continuing operations attributable to noncontrolling interest	4	37	-2	'	30
RedeemableNoncontrollingInterest [Member]	'	'	'	'	'
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]	'	'	'	'	'
(Income)/loss from continuing operations attributable to noncontrolling interest	($1,441)	($52)	'	'	($106)

IncomeLoss_Per_Operating_Partn2

Income/(Loss) Per Operating Partnership Unit (UNITED DOMINION REALTY, L.P.) Income/(Loss) Per Operating Partnership Unit (Details) (USD $)	3 Months Ended		9 Months Ended		12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2012
	instruments	instruments	instruments	instruments
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]	'	'	'	'	'
Number of Dilutive Instruments	0	0	0	0	'
Numerator for earnings per OP unit - basic and diluted:	'	'	'	'	'
Income/(loss) from continuing operations	$10,611	$2,351	$9,775	$5,713	'
Gains/(loss) on sales of real estate, net of tax	31,302	0	82,305	0	'
(Income)/loss from continuing operations attributable to noncontrolling interest	'	'	3,167	'	'
Income/(loss) from continuing operations attributable to OP unitholders	40,476	2,336	88,911	'	5,637
Income/(loss) from discontinued operations, net of tax	79	884	10	2,567	2,567
(Income)/loss from discontinued operations attributable to noncontrolling interest	-6	-32	-4	'	-92
Income (loss) from discontinued operations attributable to OP unitholders	73	852	6	2,475	'
Net income/(loss)	41,992	3,235	92,090	8,280	'
Net (income)/loss attributable to noncontrolling interests	1,500	92	3,336	364	'
Net income/(loss) attributable to OP unitholders	40,549	3,188	88,917	8,112	8,112
United Dominion Reality L.P. [Member]	'	'	'	'	'
Numerator for earnings per OP unit - basic and diluted:	'	'	'	'	'
Income/(loss) from continuing operations	8,875	10,072	23,606	26,278	'
Gains/(loss) on sales of real estate, net of tax	0	0	40,687	0	'
(Income)/loss from continuing operations attributable to noncontrolling interest	-238	-39	-697	-151	'
Income/(loss) from continuing operations attributable to OP unitholders	8,637	10,033	63,596	26,127	'
Income/(loss) from discontinued operations, net of tax	0	978	0	2,766	'
(Income)/loss from discontinued operations attributable to noncontrolling interest	0	0	0	0	'
Income (loss) from discontinued operations attributable to OP unitholders	0	978	0	2,766	'
Net income/(loss)	8,875	11,050	64,293	29,044	'
Net (income)/loss attributable to noncontrolling interests	238	39	697	151	'
Net income/(loss) attributable to OP unitholders	$8,637	$11,011	$63,596	$28,893	$28,893
Denominator for earnings per OP unit - basic and diluted	'	'	'	'	'
Weighted average OP units outstanding	183,279	184,281	183,279	184,281	'
Income/(loss) from continuing operations attributable to OP unitholders (in dollars per share)	$0.05	$0.05	$0.35	$0.14	'
Income/(loss) from discontinued operations (in dollars per share)	$0	$0.01	$0	$0.02	'
Net income/(loss) attributable to OP unitholders (in dollars per share)	$0.05	$0.06	$0.35	$0.16	'

Noncontrolling_Interests_Detai

Noncontrolling Interests (Details) (USD $)	3 Months Ended		9 Months Ended		12 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2012
Noncontrolling Interest [Line Items]	'	'	'	'	'
Net Income (Loss) Available to Common Stockholders, Basic	$39,618	$2,257	$86,124	$5,319	$5,319
Change in equity from net income(loss) attributable to common stockholders and conversion of OP Units to UDR Common Stock	43,745	2,257	90,442	'	7,030
Redeemable noncontrolling interests in the Operating Partnership	'	'	'	'	'
Redeemable non-controlling interests in operating partnership	'	'	217,597	'	'
Mark to market adjustment to redeemable noncontrolling interests in the Operating Partnership	'	'	40,771	'	'
Conversion of OP Units to Common Stock	-4,127	0	-4,318	-1,711	-1,711
Net (income)/loss attributable to redeemable non-controlling interests in Operating Partnership	1,447	84	3,171	198	198
Distributions to redeemable noncontrolling interests in the Operating Partnership	'	'	-7,570	'	'
Redeemable non-controlling interests in operating partnership	249,814	'	249,814	'	'
Net income attributable to non-controlling interests	($4)	($37)	$2	($30)	'

Related_Party_Transactions_UNI1

Related Party Transactions (UNITED DOMINION REALTY, L.P.) (Details) (USD $)

3 Months Ended

9 Months Ended

12 Months Ended

3 Months Ended

9 Months Ended

9 Months Ended

3 Months Ended

9 Months Ended

12 Months Ended

9 Months Ended

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Dec. 31, 2012

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Dec. 31, 2012

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

United Dominion Reality L.P. [Member]

United Dominion Reality L.P. [Member]

United Dominion Reality L.P. [Member]

United Dominion Reality L.P. [Member]

United Dominion Reality L.P. [Member]

United Dominion Reality L.P. [Member]

United Dominion Reality L.P. [Member]

United Dominion Reality L.P. [Member]

United Dominion Reality L.P. [Member]

United Dominion Reality L.P. [Member]

United Dominion Reality L.P. [Member]

United Dominion Reality L.P. [Member]

United Dominion Reality L.P. [Member]

United Dominion Reality L.P. [Member]

Fixed Rate Debt [Member]

Bottom Dollar Guaranty [Member]

Taxable REIT Subsidiaries [Member]

Taxable REIT Subsidiaries [Member]

UDR, Inc. [Member]

UDR, Inc. [Member]

UDR, Inc. [Member]

UDR, Inc. [Member]

UDR, Inc. [Member]

UDR, Inc. [Member]

UDR, Inc. [Member]

United Dominion Reality L.P. [Member]

Fixed Rate Debt [Member]

Bottom Dollar Guaranty [Member]

Bottom Dollar Guaranty [Member]

Guaranty Related To Community Acquisition [Member]

Guaranty Related To Community Acquisition [Member]

United Dominion Reality L.P. [Member]

Related Party Transaction [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Net receivable balances from General Partner

'

'

'

'

'

$795,000

'

$795,000

'

($9,916,000)

($795,000)

$9,916,000

'

'

'

'

'

'

'

'

'

General and administrative expenses allocated to the Operating Partnership by UDR

'

'

'

'

'

'

'

'

'

'

'

'

6,600,000

6,500,000

20,500,000

17,400,000

'

'

'

'

'

Related Party Transaction, Management Fee Percentage

'

'

'

'

'

'

'

2.75%

'

'

2.75%

'

'

'

'

'

'

'

'

'

'

Related party management fees

3,200,000

3,100,000

9,400,000

'

9,100,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Related party guaranty note payable interest rate

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

5.18%

'

5.34%

'

'

Debt Instrument, Maturity Date Range, End

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

31-Aug-21

31-Dec-23

Interest Expense, Related Party

1,200,000

3,500,000

300,000

800,000

'

1,151,000

267,000

3,453,000

801,000

'

'

'

'

'

'

'

'

'

'

'

'

Notes payable due to General Partner

'

'

'

'

'

$88,696,000

'

$88,696,000

'

$88,696,000

'

'

'

'

'

'

$88,700,000

$88,700,000

'

'

'

Fair_Value_of_Derivatives_and_4

Fair Value of Derivatives and Financial Instruments (Details) (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014		Dec. 31, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers, Net	$0		'
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis	'		'
Derivatives - Interest rate contracts	299		0
Derivatives - Interest rate contracts (b)	2,382		4,965
Unsecured debt instruments	'		'
Redeemable noncontrolling interests in the Operating Partnership (d)	249,814		217,597
Fair Value, Measurements, Recurring [Member]	'		'
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis	'		'
Notes receivable (a)	18,858		'
Total assets	19,157		'
Unsecured debt instruments	'		'
Total liabilities	3,742,913		3,651,141
Redeemable noncontrolling interests in the Operating Partnership (d)	249,814		217,597
Interest Rate Contracts [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis	'		'
Derivatives - Interest rate contracts	299	[1]	'
Derivatives - Interest rate contracts (b)	2,382	[1]	4,965	[1]
Mortgages Notes Payable [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Secured debt instruments - fixed rate	'		'
Secured debt instruments - fixed rate	451,582	[2]	466,375	[2]
Secured debt instruments - variable rate	'		'
Secured debt instruments - variable rate	31,337	[2]	63,595	[2]
Tax Exempt Notes Payable [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Secured debt instruments - variable rate	'		'
Secured debt instruments - variable rate	94,700	[2]	94,700	[2]
Line of Credit [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Secured debt instruments - fixed rate	'		'
Secured debt instruments - fixed rate	655,035	[2]	661,094	[2]
Secured debt instruments - variable rate	'		'
Secured debt instruments - variable rate	211,409	[2]	211,409	[2]
Commercial bank [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Unsecured debt instruments	'		'
Unsecured debt instruments (c)	160,000	[3]	'
Senior Unsecured Notes [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Unsecured debt instruments	'		'
Unsecured debt instruments (c)	2,136,468	[3]	2,149,003	[3]
Level 1 [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis	'		'
Notes receivable (a)	0		'
Total assets	0		'
Unsecured debt instruments	'		'
Total liabilities	0		0
Level 2 [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis	'		'
Notes receivable (a)	0		'
Total assets	299		'
Unsecured debt instruments	'		'
Total liabilities	2,382		4,965
Level 3 [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis	'		'
Total assets	18,858		'
Unsecured debt instruments	'		'
Total liabilities	3,740,531		3,646,176
Carrying (Reported) Amount, Fair Value Disclosure [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis	'		'
Notes receivable (a)	18,318		83,033
Total assets	18,617		83,033
Unsecured debt instruments	'		'
Total liabilities	3,630,574		3,528,668
Redeemable noncontrolling interests in the Operating Partnership (d)	249,814		217,597
Carrying (Reported) Amount, Fair Value Disclosure [Member] | Interest Rate Contracts [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis	'		'
Derivatives - Interest rate contracts (b)	2,382		4,965
Carrying (Reported) Amount, Fair Value Disclosure [Member] | Mortgages Notes Payable [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Secured debt instruments - fixed rate	'		'
Secured debt instruments - fixed rate	438,172		445,706
Secured debt instruments - variable rate	'		'
Secured debt instruments - variable rate	31,337		63,595
Carrying (Reported) Amount, Fair Value Disclosure [Member] | Tax Exempt Notes Payable [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Secured debt instruments - variable rate	'		'
Secured debt instruments - variable rate	94,700		94,700
Carrying (Reported) Amount, Fair Value Disclosure [Member] | Line of Credit [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Secured debt instruments - fixed rate	'		'
Secured debt instruments - fixed rate	623,754		626,667
Secured debt instruments - variable rate	'		'
Secured debt instruments - variable rate	211,409		211,409
Carrying (Reported) Amount, Fair Value Disclosure [Member] | Commercial bank [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Unsecured debt instruments	'		'
Unsecured debt instruments (c)	160,000		'
Carrying (Reported) Amount, Fair Value Disclosure [Member] | Senior Unsecured Notes [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Unsecured debt instruments	'		'
Unsecured debt instruments (c)	2,068,820		2,081,626
Estimate of Fair Value, Fair Value Disclosure [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis	'		'
Notes receivable (a)	'		83,833
Total assets	'		83,833
Estimate of Fair Value, Fair Value Disclosure [Member] | Level 1 [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis	'		'
Notes receivable (a)	'		0
Total assets	'		0
Unsecured debt instruments	'		'
Redeemable noncontrolling interests in the Operating Partnership (d)	0		0
Estimate of Fair Value, Fair Value Disclosure [Member] | Level 1 [Member] | Interest Rate Contracts [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis	'		'
Derivatives - Interest rate contracts	0		'
Derivatives - Interest rate contracts (b)	0		0
Estimate of Fair Value, Fair Value Disclosure [Member] | Level 1 [Member] | Mortgages Notes Payable [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Secured debt instruments - fixed rate	'		'
Secured debt instruments - fixed rate	0		0
Secured debt instruments - variable rate	'		'
Secured debt instruments - variable rate	0		0
Estimate of Fair Value, Fair Value Disclosure [Member] | Level 1 [Member] | Tax Exempt Notes Payable [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Secured debt instruments - variable rate	'		'
Secured debt instruments - variable rate	0		0
Estimate of Fair Value, Fair Value Disclosure [Member] | Level 1 [Member] | Line of Credit [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Secured debt instruments - fixed rate	'		'
Secured debt instruments - fixed rate	0		0
Secured debt instruments - variable rate	'		'
Secured debt instruments - variable rate	0		0
Estimate of Fair Value, Fair Value Disclosure [Member] | Level 1 [Member] | Commercial bank [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Unsecured debt instruments	'		'
Unsecured debt instruments (c)	0		'
Estimate of Fair Value, Fair Value Disclosure [Member] | Level 1 [Member] | Senior Unsecured Notes [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Unsecured debt instruments	'		'
Unsecured debt instruments (c)	0		0
Estimate of Fair Value, Fair Value Disclosure [Member] | Level 2 [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis	'		'
Notes receivable (a)	'		0
Total assets	'		0
Estimate of Fair Value, Fair Value Disclosure [Member] | Level 2 [Member] | Interest Rate Contracts [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis	'		'
Derivatives - Interest rate contracts	299		'
Derivatives - Interest rate contracts (b)	2,382		'
Estimate of Fair Value, Fair Value Disclosure [Member] | Level 2 [Member] | Mortgages Notes Payable [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Secured debt instruments - fixed rate	'		'
Secured debt instruments - fixed rate	0		0
Secured debt instruments - variable rate	'		'
Secured debt instruments - variable rate	0		0
Estimate of Fair Value, Fair Value Disclosure [Member] | Level 2 [Member] | Tax Exempt Notes Payable [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Secured debt instruments - variable rate	'		'
Secured debt instruments - variable rate	0		0
Estimate of Fair Value, Fair Value Disclosure [Member] | Level 2 [Member] | Line of Credit [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Secured debt instruments - fixed rate	'		'
Secured debt instruments - fixed rate	0		0
Secured debt instruments - variable rate	'		'
Secured debt instruments - variable rate	0		0
Estimate of Fair Value, Fair Value Disclosure [Member] | Level 2 [Member] | Commercial bank [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Unsecured debt instruments	'		'
Unsecured debt instruments (c)	0		'
Estimate of Fair Value, Fair Value Disclosure [Member] | Level 2 [Member] | Senior Unsecured Notes [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Unsecured debt instruments	'		'
Unsecured debt instruments (c)	0		0
Estimate of Fair Value, Fair Value Disclosure [Member] | Level 3 [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis	'		'
Notes receivable (a)	18,858		83,833
Total assets	'		83,833
Unsecured debt instruments	'		'
Redeemable noncontrolling interests in the Operating Partnership (d)	0		0
Estimate of Fair Value, Fair Value Disclosure [Member] | Level 3 [Member] | Interest Rate Contracts [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis	'		'
Derivatives - Interest rate contracts	0		'
Derivatives - Interest rate contracts (b)	0		0
Estimate of Fair Value, Fair Value Disclosure [Member] | Level 3 [Member] | Mortgages Notes Payable [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Secured debt instruments - fixed rate	'		'
Secured debt instruments - fixed rate	451,582		466,375
Secured debt instruments - variable rate	'		'
Secured debt instruments - variable rate	31,337		63,595
Estimate of Fair Value, Fair Value Disclosure [Member] | Level 3 [Member] | Tax Exempt Notes Payable [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Secured debt instruments - variable rate	'		'
Secured debt instruments - variable rate	94,700		94,700
Estimate of Fair Value, Fair Value Disclosure [Member] | Level 3 [Member] | Line of Credit [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Secured debt instruments - fixed rate	'		'
Secured debt instruments - fixed rate	655,035		661,094
Secured debt instruments - variable rate	'		'
Secured debt instruments - variable rate	211,409		211,409
Estimate of Fair Value, Fair Value Disclosure [Member] | Level 3 [Member] | Commercial bank [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Unsecured debt instruments	'		'
Unsecured debt instruments (c)	160,000		'
Estimate of Fair Value, Fair Value Disclosure [Member] | Level 3 [Member] | Senior Unsecured Notes [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Unsecured debt instruments	'		'
Unsecured debt instruments (c)	$2,136,468		$2,149,003
[1]	See Note 6, Secured and Unsecured Debt
[2]	See Note 2, Significant Accounting Policies
[3]	See Note 10, Derivatives and Hedging Activity

Fair_Value_of_Derivatives_and_5

Fair Value of Derivatives and Financial Instruments (UNITED DOMINION REALTY, L.P.) (Details) (USD $)	Sep. 30, 2014		Dec. 31, 2013
In Thousands, unless otherwise specified
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis	'		'
Derivatives - Interest rate contracts	$299		$0
Derivative Liability Designated as Hedging Instrument, Fair Value	2,382		4,965
Fair Value, Measurements, Recurring [Member]	'		'
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis	'		'
Total assets	19,157		'
Secured debt instruments - variable rate	'		'
Total liabilities	3,742,913		3,651,141
Interest Rate Contracts [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis	'		'
Derivatives - Interest rate contracts	299	[1]	'
Derivative Liability Designated as Hedging Instrument, Fair Value	2,382	[1]	4,965	[1]
Mortgages Notes Payable [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Secured debt instruments - fixed rate	'		'
Secured debt instruments - fixed rate	451,582	[2]	466,375	[2]
Secured debt instruments - variable rate	'		'
Secured debt instruments - variable rate	31,337	[2]	63,595	[2]
Tax Exempt Notes Payable [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Secured debt instruments - variable rate	'		'
Secured debt instruments - variable rate	94,700	[2]	94,700	[2]
Line of Credit [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Secured debt instruments - fixed rate	'		'
Secured debt instruments - fixed rate	655,035	[2]	661,094	[2]
Secured debt instruments - variable rate	'		'
Secured debt instruments - variable rate	211,409	[2]	211,409	[2]
Level 1 [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis	'		'
Total assets	0		'
Secured debt instruments - variable rate	'		'
Total liabilities	0		0
Level 2 [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis	'		'
Total assets	299		'
Secured debt instruments - variable rate	'		'
Total liabilities	2,382		4,965
Level 3 [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis	'		'
Total assets	18,858		'
Secured debt instruments - variable rate	'		'
Total liabilities	3,740,531		3,646,176
United Dominion Reality L.P. [Member]	'		'
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis	'		'
Derivatives - Interest rate contracts	5		0
Derivative Liability Designated as Hedging Instrument, Fair Value	1,324		2,731
United Dominion Reality L.P. [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis	'		'
Total assets	5		'
Secured debt instruments - variable rate	'		'
Total liabilities	958,115		969,724
United Dominion Reality L.P. [Member] | Interest Rate Contracts [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis	'		'
Derivatives - Interest rate contracts	5	[3]	'
Derivative Liability Designated as Hedging Instrument, Fair Value	1,324	[3]	2,731	[3]
United Dominion Reality L.P. [Member] | Mortgages Notes Payable [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Secured debt instruments - fixed rate	'		'
Secured debt instruments - fixed rate	392,883	[4]	403,695	[4]
United Dominion Reality L.P. [Member] | Tax Exempt Notes Payable [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Secured debt instruments - variable rate	'		'
Secured debt instruments - variable rate	27,000	[4]	27,000	[4]
United Dominion Reality L.P. [Member] | Line of Credit [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Secured debt instruments - fixed rate	'		'
Secured debt instruments - fixed rate	394,849	[4]	394,239	[4]
Secured debt instruments - variable rate	'		'
Secured debt instruments - variable rate	142,059	[4]	142,059	[4]
United Dominion Reality L.P. [Member] | Level 1 [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis	'		'
Total assets	0		'
Secured debt instruments - variable rate	'		'
Total liabilities	0		0
United Dominion Reality L.P. [Member] | Level 2 [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis	'		'
Total assets	5		'
Secured debt instruments - variable rate	'		'
Total liabilities	1,324		2,731
United Dominion Reality L.P. [Member] | Level 3 [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis	'		'
Total assets	0		'
Secured debt instruments - variable rate	'		'
Total liabilities	956,791		966,993
Estimate of Fair Value, Fair Value Disclosure [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis	'		'
Total assets	'		83,833
Estimate of Fair Value, Fair Value Disclosure [Member] | Level 1 [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis	'		'
Total assets	'		0
Estimate of Fair Value, Fair Value Disclosure [Member] | Level 1 [Member] | Interest Rate Contracts [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis	'		'
Derivatives - Interest rate contracts	0		'
Derivative Liability Designated as Hedging Instrument, Fair Value	0		0
Estimate of Fair Value, Fair Value Disclosure [Member] | Level 1 [Member] | Mortgages Notes Payable [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Secured debt instruments - fixed rate	'		'
Secured debt instruments - fixed rate	0		0
Secured debt instruments - variable rate	'		'
Secured debt instruments - variable rate	0		0
Estimate of Fair Value, Fair Value Disclosure [Member] | Level 1 [Member] | Tax Exempt Notes Payable [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Secured debt instruments - variable rate	'		'
Secured debt instruments - variable rate	0		0
Estimate of Fair Value, Fair Value Disclosure [Member] | Level 1 [Member] | Line of Credit [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Secured debt instruments - fixed rate	'		'
Secured debt instruments - fixed rate	0		0
Secured debt instruments - variable rate	'		'
Secured debt instruments - variable rate	0		0
Estimate of Fair Value, Fair Value Disclosure [Member] | Level 2 [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis	'		'
Total assets	'		0
Estimate of Fair Value, Fair Value Disclosure [Member] | Level 2 [Member] | Interest Rate Contracts [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis	'		'
Derivatives - Interest rate contracts	299		'
Derivative Liability Designated as Hedging Instrument, Fair Value	2,382		'
Estimate of Fair Value, Fair Value Disclosure [Member] | Level 2 [Member] | Mortgages Notes Payable [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Secured debt instruments - fixed rate	'		'
Secured debt instruments - fixed rate	0		0
Secured debt instruments - variable rate	'		'
Secured debt instruments - variable rate	0		0
Estimate of Fair Value, Fair Value Disclosure [Member] | Level 2 [Member] | Tax Exempt Notes Payable [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Secured debt instruments - variable rate	'		'
Secured debt instruments - variable rate	0		0
Estimate of Fair Value, Fair Value Disclosure [Member] | Level 2 [Member] | Line of Credit [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Secured debt instruments - fixed rate	'		'
Secured debt instruments - fixed rate	0		0
Secured debt instruments - variable rate	'		'
Secured debt instruments - variable rate	0		0
Estimate of Fair Value, Fair Value Disclosure [Member] | Level 3 [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis	'		'
Total assets	'		83,833
Estimate of Fair Value, Fair Value Disclosure [Member] | Level 3 [Member] | Interest Rate Contracts [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis	'		'
Derivatives - Interest rate contracts	0		'
Derivative Liability Designated as Hedging Instrument, Fair Value	0		0
Estimate of Fair Value, Fair Value Disclosure [Member] | Level 3 [Member] | Mortgages Notes Payable [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Secured debt instruments - fixed rate	'		'
Secured debt instruments - fixed rate	451,582		466,375
Secured debt instruments - variable rate	'		'
Secured debt instruments - variable rate	31,337		63,595
Estimate of Fair Value, Fair Value Disclosure [Member] | Level 3 [Member] | Tax Exempt Notes Payable [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Secured debt instruments - variable rate	'		'
Secured debt instruments - variable rate	94,700		94,700
Estimate of Fair Value, Fair Value Disclosure [Member] | Level 3 [Member] | Line of Credit [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Secured debt instruments - fixed rate	'		'
Secured debt instruments - fixed rate	655,035		661,094
Secured debt instruments - variable rate	'		'
Secured debt instruments - variable rate	211,409		211,409
Estimate of Fair Value, Fair Value Disclosure [Member] | United Dominion Reality L.P. [Member] | Level 1 [Member] | Interest Rate Contracts [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis	'		'
Derivatives - Interest rate contracts	0		'
Derivative Liability Designated as Hedging Instrument, Fair Value	0		0
Estimate of Fair Value, Fair Value Disclosure [Member] | United Dominion Reality L.P. [Member] | Level 1 [Member] | Mortgages Notes Payable [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Secured debt instruments - fixed rate	'		'
Secured debt instruments - fixed rate	0		0
Estimate of Fair Value, Fair Value Disclosure [Member] | United Dominion Reality L.P. [Member] | Level 1 [Member] | Tax Exempt Notes Payable [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Secured debt instruments - variable rate	'		'
Secured debt instruments - variable rate	0		0
Estimate of Fair Value, Fair Value Disclosure [Member] | United Dominion Reality L.P. [Member] | Level 1 [Member] | Line of Credit [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Secured debt instruments - fixed rate	'		'
Secured debt instruments - fixed rate	0		0
Secured debt instruments - variable rate	'		'
Secured debt instruments - variable rate	0		0
Estimate of Fair Value, Fair Value Disclosure [Member] | United Dominion Reality L.P. [Member] | Level 2 [Member] | Interest Rate Contracts [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis	'		'
Derivatives - Interest rate contracts	5		'
Derivative Liability Designated as Hedging Instrument, Fair Value	1,324		2,731
Estimate of Fair Value, Fair Value Disclosure [Member] | United Dominion Reality L.P. [Member] | Level 2 [Member] | Mortgages Notes Payable [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Secured debt instruments - fixed rate	'		'
Secured debt instruments - fixed rate	0		0
Estimate of Fair Value, Fair Value Disclosure [Member] | United Dominion Reality L.P. [Member] | Level 2 [Member] | Tax Exempt Notes Payable [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Secured debt instruments - variable rate	'		'
Secured debt instruments - variable rate	0		0
Estimate of Fair Value, Fair Value Disclosure [Member] | United Dominion Reality L.P. [Member] | Level 2 [Member] | Line of Credit [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Secured debt instruments - fixed rate	'		'
Secured debt instruments - fixed rate	0		0
Secured debt instruments - variable rate	'		'
Secured debt instruments - variable rate	0		0
Estimate of Fair Value, Fair Value Disclosure [Member] | United Dominion Reality L.P. [Member] | Level 3 [Member] | Interest Rate Contracts [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis	'		'
Derivatives - Interest rate contracts	0		'
Derivative Liability Designated as Hedging Instrument, Fair Value	0		0
Estimate of Fair Value, Fair Value Disclosure [Member] | United Dominion Reality L.P. [Member] | Level 3 [Member] | Mortgages Notes Payable [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Secured debt instruments - fixed rate	'		'
Secured debt instruments - fixed rate	392,883		403,695
Estimate of Fair Value, Fair Value Disclosure [Member] | United Dominion Reality L.P. [Member] | Level 3 [Member] | Tax Exempt Notes Payable [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Secured debt instruments - variable rate	'		'
Secured debt instruments - variable rate	27,000		27,000
Estimate of Fair Value, Fair Value Disclosure [Member] | United Dominion Reality L.P. [Member] | Level 3 [Member] | Line of Credit [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Secured debt instruments - fixed rate	'		'
Secured debt instruments - fixed rate	394,849		394,239
Secured debt instruments - variable rate	'		'
Secured debt instruments - variable rate	142,059		142,059
Carrying (Reported) Amount, Fair Value Disclosure [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis	'		'
Total assets	18,617		83,033
Secured debt instruments - variable rate	'		'
Total liabilities	3,630,574		3,528,668
Carrying (Reported) Amount, Fair Value Disclosure [Member] | Interest Rate Contracts [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis	'		'
Derivative Liability Designated as Hedging Instrument, Fair Value	2,382		4,965
Carrying (Reported) Amount, Fair Value Disclosure [Member] | Mortgages Notes Payable [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Secured debt instruments - fixed rate	'		'
Secured debt instruments - fixed rate	438,172		445,706
Secured debt instruments - variable rate	'		'
Secured debt instruments - variable rate	31,337		63,595
Carrying (Reported) Amount, Fair Value Disclosure [Member] | Tax Exempt Notes Payable [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Secured debt instruments - variable rate	'		'
Secured debt instruments - variable rate	94,700		94,700
Carrying (Reported) Amount, Fair Value Disclosure [Member] | Line of Credit [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Secured debt instruments - fixed rate	'		'
Secured debt instruments - fixed rate	623,754		626,667
Secured debt instruments - variable rate	'		'
Secured debt instruments - variable rate	211,409		211,409
Carrying (Reported) Amount, Fair Value Disclosure [Member] | United Dominion Reality L.P. [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis	'		'
Total assets	5		'
Secured debt instruments - variable rate	'		'
Total liabilities	929,598		937,596
Carrying (Reported) Amount, Fair Value Disclosure [Member] | United Dominion Reality L.P. [Member] | Interest Rate Contracts [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis	'		'
Derivative Liability Designated as Hedging Instrument, Fair Value	1,324		2,731
Carrying (Reported) Amount, Fair Value Disclosure [Member] | United Dominion Reality L.P. [Member] | Mortgages Notes Payable [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Secured debt instruments - fixed rate	'		'
Secured debt instruments - fixed rate	380,506		386,803
Carrying (Reported) Amount, Fair Value Disclosure [Member] | United Dominion Reality L.P. [Member] | Tax Exempt Notes Payable [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Secured debt instruments - variable rate	'		'
Secured debt instruments - variable rate	27,000		27,000
Carrying (Reported) Amount, Fair Value Disclosure [Member] | United Dominion Reality L.P. [Member] | Line of Credit [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Secured debt instruments - fixed rate	'		'
Secured debt instruments - fixed rate	378,709		379,003
Secured debt instruments - variable rate	'		'
Secured debt instruments - variable rate	$142,059		$142,059
[1]	See Note 6, Secured and Unsecured Debt
[2]	See Note 2, Significant Accounting Policies
[3]	See Note 5, Debt
[4]	See Note 8, Derivatives and Hedging Activity

Derivatives_and_Hedging_Activi4

Derivatives and Hedging Activity (Details) (Designated as Hedging Instrument [Member], USD $)	Sep. 30, 2014
In Thousands, unless otherwise specified	instruments
Interest rate swaps [Member]	'
Derivative [Line Items]	'
Number instruments	14
Notional	$419,787
Interest rate caps [Member]	'
Derivative [Line Items]	'
Number instruments	6
Notional	$339,488

Derivatives_and_Hedging_Activi5

Derivatives and Hedging Activity (Details 1) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Fair value of Company's derivative financial instruments and their classification on Consolidated Balance Sheet	'	'
Derivative Asset Designated as Hedging Instrument, Fair Value	$299	$0
Derivative Liability Designated as Hedging Instrument, Fair Value	2,382	4,965
Interest Rate Products [Member] | Other Assets [Member] | Designated as Hedging Instrument [Member]	'	'
Fair value of Company's derivative financial instruments and their classification on Consolidated Balance Sheet	'	'
Derivative Asset Designated as Hedging Instrument, Fair Value	299	'
Interest Rate Products [Member] | Other Assets [Member] | Not Designated as Hedging Instrument [Member]	'	'
Fair value of Company's derivative financial instruments and their classification on Consolidated Balance Sheet	'	'
Derivative Asset Not Designated as Hedging Instrument, Fair Value	0	0
Interest Rate Products [Member] | Other Liabilities [Member] | Designated as Hedging Instrument [Member]	'	'
Fair value of Company's derivative financial instruments and their classification on Consolidated Balance Sheet	'	'
Derivative Liability Designated as Hedging Instrument, Fair Value	2,382	'
Interest Rate Products [Member] | Other Liabilities [Member] | Not Designated as Hedging Instrument [Member]	'	'
Fair value of Company's derivative financial instruments and their classification on Consolidated Balance Sheet	'	'
Derivative Liability Not Designated as Hedging Instrument, Fair Value	$0	$0

Derivatives_and_Hedging_Activi6

Derivatives and Hedging Activity (Details 2) (USD $)	3 Months Ended		9 Months Ended		12 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2012
Effect of derivative instruments on the Consolidated Statements of Operations	'	'	'	'	'
Amount of Gain or (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	$1,130	$1,635	$3,809	$5,180	'
Amount of Gain or (Loss) Recognized in Income on Derivative	0	280	0	'	275
Interest Rate Products [Member] | Interest Expense [Member] | Cash Flow Hedging [Member]	'	'	'	'	'
Effect of derivative instruments on the Consolidated Statements of Operations	'	'	'	'	'
Amount of Gain or (Loss) Recognized in OCI on Derivative (Effective Portion)	362	-386	611	'	-334
Amount of Gain or (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	-1,130	-1,635	-3,809	'	-5,180
Amount of Gain or (Loss) Recognized in Income on Derivative (Ineffective Portion and Amount Excluded from Effectiveness Testing)	$0	$0	$3	'	$0

Derivatives_and_Hedging_Activi7

Derivatives and Hedging Activity (Details 3) (USD $)	Sep. 30, 2014		Dec. 31, 2013
In Thousands, unless otherwise specified
Offsetting Derivative Assets [Abstract]	'		'
Derivative Asset Designated as Hedging Instrument, Fair Value	$299		$0
Gross Amounts Offset in the Consolidated Balance Sheets	0		0
Net Amounts of Assets Presented in the Consolidated Balance Sheets (a)	299	[1]	0	[1]
Gross Amounts Not Offset in the Consolidated Balance Sheets, Financial Instruments	-253		0
Gross Amounts Not Offset in the Consolidated Balance Sheets, Cash Collateral Received	0		0
Net Amount	46		0
Offsetting Derivative Liabilities [Abstract]	'		'
Derivatives - Interest rate contracts (b)	2,382		4,965
Gross Amounts Offset in the Consolidated Balance Sheets	0		0
Net Amounts of Liabilities Presented in the Consolidated Balance Sheets (b)	2,382	[2]	4,965	[2]
Gross Amounts Not Offset in the Consolidated Balance Sheets, Financial Instruments	-253		0
Gross Amounts Not Offset in the Consolidated Balance Sheets, Cash Collateral Received	0		0
Net Amount	$2,129		$4,965
[1]	Amounts reconcile to the aggregate fair value of derivative assets in the bTabular Disclosure of Fair Values of Derivative Instruments on the Balance Sheetb located in this footnote.
[2]	Amounts reconcile to the aggregate fair value of derivative liabilities in the bTabular Disclosure of Fair Values of Derivative Instruments on the Balance Sheetb located in this footnote

Derivatives_and_Hedging_Activi8

Derivatives and Hedging Activity (Details Textual) (USD $)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2012	Dec. 31, 2013
Derivatives, Fair Value [Line Items]	'	'	'	'	'	'
Derivative, Collateral, Obligation to Return Cash	$0	'	$0	'	'	$0
Derivatives And Hedging Activity (Textual) [Abstract]	'	'	'	'	'	'
Cash flow hedge ineffectiveness in earnings materiality	'$3,000	'less than a B $1,000	'3000	'less than $1,000	'	'
Estimated additional accumulated other comprehensive Income/(Loss) transferred to interest expense	4,400,000	'	4,400,000	'	'	'
Derivative instruments not designated as hedging instruments, gain (loss), net	0	280,000	0	'	275,000	'
Fair value of derivatives in a net liability position	2,400,000	'	2,400,000	'	'	'
Payment required to pay for contract termination	$2,400,000	'	$2,400,000	'	'	'

Derivatives_and_Hedging_Activi9

Derivatives and Hedging Activity (UNITED DOMINION REALTY, L.P.) (Details) (Designated as Hedging Instrument [Member], USD $)	Sep. 30, 2014
In Thousands, unless otherwise specified	instruments
Interest rate swaps [Member]	'
Derivative [Line Items]	'
Number instruments	14
Notional	$419,787
Interest rate caps [Member]	'
Derivative [Line Items]	'
Number instruments	6
Notional	339,488
United Dominion Reality L.P. [Member] | Interest rate swaps [Member]	'
Derivative [Line Items]	'
Number instruments	2
Notional	96,974
United Dominion Reality L.P. [Member] | Interest rate caps [Member]	'
Derivative [Line Items]	'
Number instruments	5
Notional	$255,561

Recovered_Sheet1

Derivatives and Hedging Activity (UNITED DOMINION REALTY, L.P.) (Details 1) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Derivative Assets (Liabilities), at Fair Value, Net, by Balance Sheet Classification [Abstract]	'	'
Derivative Asset Designated as Hedging Instrument, Fair Value	$299	$0
Derivative Liability Designated as Hedging Instrument, Fair Value	2,382	4,965
Interest Rate Products [Member] | Other Assets [Member] | Designated as Hedging Instrument [Member]	'	'
Derivative Assets (Liabilities), at Fair Value, Net, by Balance Sheet Classification [Abstract]	'	'
Derivative Asset Designated as Hedging Instrument, Fair Value	299	'
Interest Rate Products [Member] | Other Assets [Member] | Not Designated as Hedging Instrument [Member]	'	'
Derivative Assets (Liabilities), at Fair Value, Net, by Balance Sheet Classification [Abstract]	'	'
Derivative Asset Not Designated as Hedging Instrument, Fair Value	0	0
Interest Rate Products [Member] | Other Liabilities [Member] | Designated as Hedging Instrument [Member]	'	'
Derivative Assets (Liabilities), at Fair Value, Net, by Balance Sheet Classification [Abstract]	'	'
Derivative Liability Designated as Hedging Instrument, Fair Value	2,382	'
Interest Rate Products [Member] | Other Liabilities [Member] | Not Designated as Hedging Instrument [Member]	'	'
Derivative Assets (Liabilities), at Fair Value, Net, by Balance Sheet Classification [Abstract]	'	'
Derivative Liability Not Designated as Hedging Instrument, Fair Value	0	0
United Dominion Reality L.P. [Member]	'	'
Derivative Assets (Liabilities), at Fair Value, Net, by Balance Sheet Classification [Abstract]	'	'
Derivative Asset Designated as Hedging Instrument, Fair Value	5	0
Derivative Liability Designated as Hedging Instrument, Fair Value	1,324	2,731
United Dominion Reality L.P. [Member] | Interest Rate Products [Member] | Other Assets [Member] | Designated as Hedging Instrument [Member]	'	'
Derivative Assets (Liabilities), at Fair Value, Net, by Balance Sheet Classification [Abstract]	'	'
Derivative Asset Designated as Hedging Instrument, Fair Value	5	0
United Dominion Reality L.P. [Member] | Interest Rate Products [Member] | Other Assets [Member] | Not Designated as Hedging Instrument [Member]	'	'
Derivative Assets (Liabilities), at Fair Value, Net, by Balance Sheet Classification [Abstract]	'	'
Derivative Asset Not Designated as Hedging Instrument, Fair Value	0	0
United Dominion Reality L.P. [Member] | Interest Rate Products [Member] | Other Liabilities [Member] | Designated as Hedging Instrument [Member]	'	'
Derivative Assets (Liabilities), at Fair Value, Net, by Balance Sheet Classification [Abstract]	'	'
Derivative Liability Designated as Hedging Instrument, Fair Value	1,324	2,731
United Dominion Reality L.P. [Member] | Interest Rate Products [Member] | Other Liabilities [Member] | Not Designated as Hedging Instrument [Member]	'	'
Derivative Assets (Liabilities), at Fair Value, Net, by Balance Sheet Classification [Abstract]	'	'
Derivative Liability Not Designated as Hedging Instrument, Fair Value	$0	$0

Recovered_Sheet2

Derivatives and Hedging Activity (UNITED DOMINION REALTY, L.P.) (Details 2) (USD $)	3 Months Ended		9 Months Ended		12 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2012
Derivative Instruments, Gain (Loss) [Line Items]	'	'	'	'	'
Amount of Gain or (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	$1,130	$1,635	$3,809	$5,180	'
Amount of Gain or (Loss) Recognized in Income on Derivative	0	280	0	'	275
Interest Rate Products [Member] | Interest Expense [Member] | Cash Flow Hedging [Member]	'	'	'	'	'
Derivative Instruments, Gain (Loss) [Line Items]	'	'	'	'	'
Amount of Gain or (Loss) Recognized in OCI on Derivative (Effective Portion)	362	-386	611	'	-334
Amount of Gain or (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	-1,130	-1,635	-3,809	'	-5,180
United Dominion Reality L.P. [Member]	'	'	'	'	'
Derivative Instruments, Gain (Loss) [Line Items]	'	'	'	'	'
Amount of Gain or (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	588	590	1,784	2,041	'
Amount of Gain or (Loss) Recognized in Income on Derivative	0	0	0	-5	-5
United Dominion Reality L.P. [Member] | Interest Rate Products [Member] | Interest Expense [Member] | Cash Flow Hedging [Member]	'	'	'	'	'
Derivative Instruments, Gain (Loss) [Line Items]	'	'	'	'	'
Amount of Gain or (Loss) Recognized in OCI on Derivative (Effective Portion)	-3	-201	-194	'	-284
Amount of Gain or (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	($588)	($590)	($1,784)	'	($2,041)

Recovered_Sheet3

Derivatives and Hedging Activity (UNITED DOMINION REALTY, L.P.) (Details 3) (USD $)	Sep. 30, 2014		Dec. 31, 2013
In Thousands, unless otherwise specified
Offsetting Derivative Assets [Abstract]	'		'
Derivative Asset Designated as Hedging Instrument, Fair Value	$299		$0
Gross Amounts Offset in the Consolidated Balance Sheets	0		0
Net Amounts of Assets Presented in the Consolidated Balance Sheets (a)	299	[1]	0	[1]
Gross Amounts Not Offset in the Consolidated Balance Sheets, Financial Instruments	-253		0
Gross Amounts Not Offset in the Consolidated Balance Sheets, Cash Collateral Received	0		0
Net Amount	46		0
Offsetting Derivative Liabilities [Abstract]	'		'
Derivative Liability Designated as Hedging Instrument, Fair Value	2,382		4,965
Gross Amounts Offset in the Consolidated Balance Sheets	0		0
Net Amounts of Liabilities Presented in the Consolidated Balance Sheets (b)	2,382	[2]	4,965	[2]
Gross Amounts Not Offset in the Consolidated Balance Sheets, Financial Instruments	-253		0
Gross Amounts Not Offset in the Consolidated Balance Sheets, Cash Collateral Received	0		0
Net Amount	2,129		4,965
United Dominion Reality L.P. [Member]	'		'
Offsetting Derivative Assets [Abstract]	'		'
Derivative Asset Designated as Hedging Instrument, Fair Value	5		0
Gross Amounts Offset in the Consolidated Balance Sheets	0		0
Net Amounts of Assets Presented in the Consolidated Balance Sheets (a)	5	[1]	0	[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	5		0
Offsetting Derivative Liabilities [Abstract]	'		'
Derivative Liability Designated as Hedging Instrument, Fair Value	1,324		2,731
Gross Amounts Offset in the Consolidated Balance Sheets	0		0
Net Amounts of Liabilities Presented in the Consolidated Balance Sheets (b)	1,324	[2]	2,731	[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	$1,324		$2,731
[1]	Amounts reconcile to the aggregate fair value of derivative assets in the bTabular Disclosure of Fair Values of Derivative Instruments on the Balance Sheetb located in this footnote.
[2]	Amounts reconcile to the aggregate fair value of derivative liabilities in the bTabular Disclosure of Fair Values of Derivative Instruments on the Balance Sheetb located in this footnote

Recovered_Sheet4

Derivatives and Hedging Activity (UNITED DOMINION REALTY, L.P.) (Details Textual) (USD $)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2012	Dec. 31, 2013
Entity Information [Line Items]	'	'	'	'	'	'
Cash flow hedge ineffectiveness in earnings materiality	'$3,000	'less than a B $1,000	'3000	'less than $1,000	'	'
Estimated additional accumulated other comprehensive Income/(Loss) transferred to interest expense	$4,400,000	'	$4,400,000	'	'	'
Losses in the fair value of derivatives not designated in hedging relationships	0	-280,000	0	'	-275,000	'
Fair value of derivatives in a net liability position	2,400,000	'	2,400,000	'	'	'
Payment required to pay for contract termination	2,400,000	'	2,400,000	'	'	'
Derivative, Collateral, Obligation to Return Cash	0	'	0	'	'	0
United Dominion Reality L.P. [Member]	'	'	'	'	'	'
Entity Information [Line Items]	'	'	'	'	'	'
Cash flow hedge ineffectiveness in earnings materiality	'less than a $1,000 loss	'less than a $1,000 loss	'0	'less than $1,000	'less than a $1,000 loss	'
Estimated additional accumulated other comprehensive Income/(Loss) transferred to interest expense	1,300,000	'	1,300,000	'	'	'
Losses in the fair value of derivatives not designated in hedging relationships	0	0	0	5,000	5,000	'
Fair value of derivatives in a net liability position	1,500,000	'	1,500,000	'	'	'
Payment required to pay for contract termination	1,500,000	'	1,500,000	'	'	'
Derivative, Collateral, Obligation to Return Cash	$0	'	$0	'	'	$0

Stock_Based_Compensation_Detai

Stock Based Compensation (Details) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Stock Based Compensation (Textual) [Abstract]	'	'	'	'
Stock based compensation expense	$3.50	$2.40	$10.80	$6.70

Capital_Structure_UNITED_DOMIN1

Capital Structure (UNITED DOMINION REALTY, L.P.) (Details) (USD $)	9 Months Ended
In Thousands, except Share data, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Limited Partners' Capital Account [Line Items]	'	'
General Partnership units outstanding	174,111,227	'
Redeemable noncontrolling interests in the Operating Partnership	249,814	217,597
United Dominion Reality L.P. [Member]	'	'
Limited Partners' Capital Account [Line Items]	'	'
General Partnership units outstanding	110,883	110,883
Limited partnership units owned	183,167,815	183,167,815
Limited Partners' Capital Account, Required Period To Be Outstanding Before Unit is Redeemable	'1 year	'
UDR, Inc. [Member]	'	'
Limited Partners' Capital Account [Line Items]	'	'
Limited partnership units owned	174,000,344	173,848,891
Percentage of units	95.00%	94.90%
Non-affiliated Partners [Member]	'	'
Limited Partners' Capital Account [Line Items]	'	'
Limited partnership units owned	9,167,471	9,318,924
Percentage of units	5.00%	5.10%
Class A Limited Partner [Member]	'	'
Limited Partners' Capital Account [Line Items]	'	'
Limited partnership units owned	'	1,751,671
Cumulative, annual, non-compounded preferred return on Class A Partnership units	8.00%	'
Value of Class A Partnership units (in dollars per unit)	16.61	'
Class A Limited Partner [Member] | United Dominion Reality L.P. [Member]	'	'
Limited Partners' Capital Account [Line Items]	'	'
Limited partnership units owned	1,873,332	1,751,671
Class A Limited Partner [Member] | UDR, Inc. [Member]	'	'
Limited Partners' Capital Account [Line Items]	'	'
Limited partnership units owned	121,661	'
Class A Limited Partner [Member] | Non-affiliated Partners [Member]	'	'
Limited Partners' Capital Account [Line Items]	'	'
Limited partnership units owned	1,751,671	'

Commitments_and_Contingencies_2

Commitments and Contingencies (Details) (USD $)	9 Months Ended
	Sep. 30, 2014
	property
Real Estate Properties [Line Items]	'
Number of communities owned (in communities)	141
Costs Incurred to Date	$605,034,000
Expected Costs to Complete	288,342,000	[1]
Wholly owned b under development [Member]	'
Real Estate Properties [Line Items]	'
Capital Expenditures Incurred but Not yet Paid	26,800,000
Number of communities owned (in communities)	3
Costs Incurred to Date	321,607,000
Expected Costs to Complete	78,793,000
Average Ownership Stake	100.00%
Wholly owned b redevelopment [Member]	'
Real Estate Properties [Line Items]	'
Capital Expenditures Incurred but Not yet Paid	2,100,000
Number of communities owned (in communities)	1
Costs Incurred to Date	80,619,000
Expected Costs to Complete	17,381,000
Average Ownership Stake	100.00%
Unconsolidated joint ventures [Member]	'
Real Estate Properties [Line Items]	'
Number of communities owned (in communities)	2
Costs Incurred to Date	158,986,000
Expected Costs to Complete	143,981,000
Average Ownership Stake	51.00%
Participating Loan Investment Steele Creek Denver Colorado [Member]	'
Real Estate Properties [Line Items]	'
Number of communities owned (in communities)	1
Costs Incurred to Date	43,822,000
Expected Costs to Complete	$48,187,000
Average Ownership Stake	0.00%
[1]	Costs incurred to date include $26.8 million and $2.1 million of accrued fixed assets for development and redevelopment, respectively.

Commitments_and_Contingencies_3

Commitments and Contingencies (UNITED DOMINION REALTY, L.P.) Commitments and Contingencies (Details) (USD $)	9 Months Ended
	Sep. 30, 2014
	property
Loss Contingencies [Line Items]	'
Number of communities owned (in communities)	141
Cost Incurred to Date	$605,034,000
United Dominion Reality L.P. [Member]	'
Loss Contingencies [Line Items]	'
Number of communities owned (in communities)	67
Wholly owned b redevelopment [Member]	'
Loss Contingencies [Line Items]	'
Capital Expenditures Incurred but Not yet Paid	2,100,000
Number of communities owned (in communities)	1
Cost Incurred to Date	80,619,000
Wholly owned b under development [Member]	'
Loss Contingencies [Line Items]	'
Capital Expenditures Incurred but Not yet Paid	26,800,000
Number of communities owned (in communities)	3
Cost Incurred to Date	321,607,000
Wholly owned b under development [Member] | United Dominion Reality L.P. [Member]	'
Loss Contingencies [Line Items]	'
Capital Expenditures Incurred but Not yet Paid	7,000,000
Number of communities owned (in communities)	1
Cost Incurred to Date	119,828,000
Expected Costs to Complete	$12,172,000

Reportable_Segments_Details

Reportable Segments (Details) (USD $)	3 Months Ended		9 Months Ended		12 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2012	Dec. 31, 2013
	Segments
Segment Reporting Information [Line Items]	'	'	'	'	'	'
Same Store Communities	36,268	'	35,177	'	'	'
Summary of rental income and NOI for UDRs reportable segments and reconciliation of NOI to loss from continuing operations	'	'	'	'	'	'
Reportable apartment home segment rental income	$206,752	$191,124	$608,497	$565,510	'	'
Reportable apartment home segment NOI	139,814	128,643	412,330	'	382,612	'
Reconciling items:	'	'	'	'	'	'
Joint venture management and other fees	3,165	3,207	9,599	9,347	9,347	'
Property management	-5,599	-5,236	-16,474	'	-15,491	'
Other operating expenses	-2,012	-1,787	-6,118	'	-5,237	'
Real estate depreciation and amortization	89,339	83,738	266,748	251,231	'	'
General and administrative	-11,554	-11,364	-36,078	'	-30,706	'
Casualty (Recoveries)/Charges	0	6,460	-500	12,253	-12,253	'
Other depreciation and amortization	-1,385	-1,176	-3,658	-3,460	-3,460	'
Income/(loss) from unconsolidated entities	-939	-3,794	-4,932	-6,081	-6,081	'
Interest expense	-33,087	-30,939	-97,662	-92,723	-92,723	'
Interest and other income/(expense), net	9,061	829	11,902	'	3,291	'
Gains/(loss) on sales of real estate, net of tax	31,302	0	82,305	0	'	'
Tax benefit, net	2,490	2,658	8,049	'	7,314	'
Gain on sale of real estate owned, net of tax	31,377	0	82,380	0	'	'
Net (income)/loss attributable to redeemable noncontrolling interests in the Operating Partnership	-1,447	-84	-3,171	-198	-198	'
Net (income)/loss attributable to noncontrolling interests	4	37	-2	'	30	'
Net income/(loss) attributable to UDR, Inc.	40,549	3,188	88,917	8,112	8,112	'
Reportable apartment home segment assets:	'	'	'	'	'	'
Total segment assets	8,428,291	'	8,428,291	'	'	8,207,977
Accumulated depreciation	-2,379,033	'	-2,379,033	'	'	-2,208,794
Total segment asset - net book value	6,049,258	'	6,049,258	'	'	5,999,183
Reconciling items:	'	'	'	'	'	'
Cash and cash equivalents	14,605	11,149	14,605	11,149	12,115	30,249
Restricted cash	23,969	'	23,969	'	'	22,796
Deferred financing costs, net	24,344	'	24,344	'	'	26,924
Notes receivable, net	18,318	'	18,318	'	'	83,033
Investment in and advances to unconsolidated joint ventures, net	-650,441	'	-650,441	'	'	-507,655
Other assets	117,153	'	117,153	'	'	137,882
Total consolidated assets	6,898,088	'	6,898,088	'	'	6,807,722
Reportable Segment (Textual) [Abstract]	'	'	'	'	'	'
Number of reportable segments	2	'	'	'	'	'
Condition for Community considered to have stabilized occupancy	'	'	'90% occupancy for at least three consecutive months	'	'	'
Number of Tenants or related group of tenants that contributed 10% or more of company total revenue	0	0	0	0	'	'
Same-Store [Member]	'	'	'	'	'	'
Reportable Segment (Textual) [Abstract]	'	'	'	'	'	'
SEC Schedule III, Real Estate, Improvements	15,100	14,500	36,500	'	34,600	'
Same Store Communities Western Region [Member]	'	'	'	'	'	'
Summary of rental income and NOI for UDRs reportable segments and reconciliation of NOI to loss from continuing operations	'	'	'	'	'	'
Reportable apartment home segment rental income	68,275	64,195	189,075	'	177,884	'
Reportable apartment home segment NOI	49,110	45,699	136,587	'	126,860	'
Reportable apartment home segment assets:	'	'	'	'	'	'
Total segment assets	2,591,838	'	2,591,838	'	'	2,412,091
Same Store Communities Mid-Atlantic Region [Member]	'	'	'	'	'	'
Summary of rental income and NOI for UDRs reportable segments and reconciliation of NOI to loss from continuing operations	'	'	'	'	'	'
Reportable apartment home segment rental income	40,479	40,164	121,356	'	119,937	'
Reportable apartment home segment NOI	27,622	27,629	83,581	'	83,287	'
Reportable apartment home segment assets:	'	'	'	'	'	'
Total segment assets	1,404,730	'	1,404,730	'	'	1,395,772
Same Store Communities Northeast Region [Member]	'	'	'	'	'	'
Summary of rental income and NOI for UDRs reportable segments and reconciliation of NOI to loss from continuing operations	'	'	'	'	'	'
Reportable apartment home segment rental income	20,721	19,806	45,331	'	43,441	'
Reportable apartment home segment NOI	15,571	14,678	33,361	'	31,409	'
Reportable apartment home segment assets:	'	'	'	'	'	'
Total segment assets	1,073,905	'	1,073,905	'	'	1,066,260
Same Store Communities Southeastern Region [Member]	'	'	'	'	'	'
Summary of rental income and NOI for UDRs reportable segments and reconciliation of NOI to loss from continuing operations	'	'	'	'	'	'
Reportable apartment home segment rental income	27,210	25,851	80,578	'	76,763	'
Reportable apartment home segment NOI	17,480	16,560	53,329	'	49,866	'
Reportable apartment home segment assets:	'	'	'	'	'	'
Total segment assets	783,641	'	783,641	'	'	785,134
Same Store Communities Southwestern Region [Member]	'	'	'	'	'	'
Summary of rental income and NOI for UDRs reportable segments and reconciliation of NOI to loss from continuing operations	'	'	'	'	'	'
Reportable apartment home segment rental income	13,859	13,293	40,949	'	39,012	'
Reportable apartment home segment NOI	8,509	7,983	25,130	'	23,751	'
Reportable apartment home segment assets:	'	'	'	'	'	'
Total segment assets	438,982	'	438,982	'	'	434,875
Non-Mature communities/Other [Member]	'	'	'	'	'	'
Summary of rental income and NOI for UDRs reportable segments and reconciliation of NOI to loss from continuing operations	'	'	'	'	'	'
Reportable apartment home segment rental income	33,064	27,070	121,756	'	106,256	'
Reportable apartment home segment NOI	21,522	16,094	80,342	'	67,439	'
Reportable apartment home segment assets:	'	'	'	'	'	'
Total segment assets	2,135,195	'	2,135,195	'	'	2,113,845
Reportable Segment (Textual) [Abstract]	'	'	'	'	'	'
SEC Schedule III, Real Estate, Improvements	1,343	1,567	5,001	'	4,800	'
Total Communities [Member]	'	'	'	'	'	'
Summary of rental income and NOI for UDRs reportable segments and reconciliation of NOI to loss from continuing operations	'	'	'	'	'	'
Reportable apartment home segment rental income	203,608	190,379	599,045	'	563,293	'
United Dominion Reality L.P. [Member]	'	'	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'	'	'
Same Store Communities	19,518	'	19,010	'	'	'
Summary of rental income and NOI for UDRs reportable segments and reconciliation of NOI to loss from continuing operations	'	'	'	'	'	'
Reportable apartment home segment NOI	75,753	71,993	223,138	'	214,573	'
Reconciling items:	'	'	'	'	'	'
Property management	-2,955	-2,860	-8,653	'	-8,436	'
Other operating expenses	-1,484	-1,405	-4,371	'	-4,215	'
Real estate depreciation and amortization	45,043	44,333	134,011	133,962	'	'
General and administrative	-6,939	-6,855	-21,368	'	-18,324	'
Casualty (Recoveries)/Charges	0	3,807	-500	8,083	-8,083	'
Interest expense	-10,457	-8,773	-30,629	'	-27,085	'
Gains/(loss) on sales of real estate, net of tax	0	0	40,687	0	'	'
Net (income)/loss attributable to noncontrolling interests	-238	-39	-697	'	-151	'
Net income/(loss) attributable to UDR, Inc.	8,637	11,011	63,596	28,893	28,893	'
Reportable apartment home segment assets:	'	'	'	'	'	'
Total segment assets	4,219,223	'	4,219,223	'	'	4,188,480
Accumulated depreciation	-1,358,123	'	-1,358,123	'	'	-1,241,574
Total segment asset - net book value	2,861,100	'	2,861,100	'	'	2,946,906
Reconciling items:	'	'	'	'	'	'
Cash and cash equivalents	1,484	2,422	1,484	2,422	2,804	1,897
Restricted cash	13,989	'	13,989	'	'	13,526
Deferred financing costs, net	4,783	'	4,783	'	'	5,848
Other assets	25,070	'	25,070	'	'	25,064
Total consolidated assets	2,906,426	'	2,906,426	'	'	2,993,241
Reportable Segment (Textual) [Abstract]	'	'	'	'	'	'
Related Party Transaction, Management Fee Percentage	'	'	2.75%	'	'	'
Number of reportable segments	2	'	'	'	'	'
Number of Tenants or related group of tenants that contributed 10% or more of company total revenue	0	0	0	0	'	'
United Dominion Reality L.P. [Member] | Same-Store [Member]	'	'	'	'	'	'
Reportable Segment (Textual) [Abstract]	'	'	'	'	'	'
SEC Schedule III, Real Estate, Improvements	8,600	6,900	20,000	'	18,500	'
United Dominion Reality L.P. [Member] | Same Store Communities Western Region [Member]	'	'	'	'	'	'
Summary of rental income and NOI for UDRs reportable segments and reconciliation of NOI to loss from continuing operations	'	'	'	'	'	'
Reportable apartment home segment rental income	49,279	46,246	144,252	'	135,418	'
Reportable apartment home segment NOI	35,801	33,307	105,375	'	97,533	'
Reportable apartment home segment assets:	'	'	'	'	'	'
Total segment assets	1,742,559	'	1,742,559	'	'	1,733,144
United Dominion Reality L.P. [Member] | Same Store Communities Mid-Atlantic Region [Member]	'	'	'	'	'	'
Summary of rental income and NOI for UDRs reportable segments and reconciliation of NOI to loss from continuing operations	'	'	'	'	'	'
Reportable apartment home segment rental income	17,169	17,105	51,779	'	51,095	'
Reportable apartment home segment NOI	11,422	11,483	34,888	'	34,689	'
Reportable apartment home segment assets:	'	'	'	'	'	'
Total segment assets	710,277	'	710,277	'	'	706,447
United Dominion Reality L.P. [Member] | Same Store Communities Northeast Region [Member]	'	'	'	'	'	'
Summary of rental income and NOI for UDRs reportable segments and reconciliation of NOI to loss from continuing operations	'	'	'	'	'	'
Reportable apartment home segment rental income	14,968	14,331	28,410	'	27,414	'
Reportable apartment home segment NOI	11,609	10,789	21,448	'	20,083	'
Reportable apartment home segment assets:	'	'	'	'	'	'
Total segment assets	776,310	'	776,310	'	'	770,937
United Dominion Reality L.P. [Member] | Same Store Communities Southeastern Region [Member]	'	'	'	'	'	'
Summary of rental income and NOI for UDRs reportable segments and reconciliation of NOI to loss from continuing operations	'	'	'	'	'	'
Reportable apartment home segment rental income	11,368	10,841	33,753	'	32,177	'
Reportable apartment home segment NOI	7,327	6,957	22,286	'	20,898	'
Reportable apartment home segment assets:	'	'	'	'	'	'
Total segment assets	331,727	'	331,727	'	'	328,150
United Dominion Reality L.P. [Member] | Same Store Communities Southwestern Region [Member]	'	'	'	'	'	'
Summary of rental income and NOI for UDRs reportable segments and reconciliation of NOI to loss from continuing operations	'	'	'	'	'	'
Reportable apartment home segment rental income	6,667	6,508	19,873	'	19,098	'
Reportable apartment home segment NOI	4,192	4,040	12,578	'	11,987	'
Reportable apartment home segment assets:	'	'	'	'	'	'
Total segment assets	227,886	'	227,886	'	'	226,252
United Dominion Reality L.P. [Member] | Non-Mature communities/Other [Member]	'	'	'	'	'	'
Summary of rental income and NOI for UDRs reportable segments and reconciliation of NOI to loss from continuing operations	'	'	'	'	'	'
Reportable apartment home segment rental income	7,993	8,966	36,589	'	41,564	'
Reportable apartment home segment NOI	5,402	5,417	26,563	'	29,383	'
Reportable apartment home segment assets:	'	'	'	'	'	'
Total segment assets	430,464	'	430,464	'	'	423,550
Reportable Segment (Textual) [Abstract]	'	'	'	'	'	'
SEC Schedule III, Real Estate, Improvements	137	436	555	'	1,497	'
United Dominion Reality L.P. [Member] | Total Communities [Member]	'	'	'	'	'	'
Summary of rental income and NOI for UDRs reportable segments and reconciliation of NOI to loss from continuing operations	'	'	'	'	'	'
Reportable apartment home segment rental income	107,444	103,997	314,656	'	306,766	'
Taxable REIT Subsidiaries [Member] | United Dominion Reality L.P. [Member]	'	'	'	'	'	'
Reportable Segment (Textual) [Abstract]	'	'	'	'	'	'
Related Party Transaction, Management Fee Percentage	'	'	2.75%	'	'	'
Segment Reconciling Items [Member]	'	'	'	'	'	'
Reconciling items:	'	'	'	'	'	'
Real estate depreciation and amortization	89,339	84,266	266,748	'	252,839	'
Segment Reconciling Items [Member] | United Dominion Reality L.P. [Member]	'	'	'	'	'	'
Reconciling items:	'	'	'	'	'	'
Real estate depreciation and amortization	$45,043	$44,857	$134,011	'	$135,552	'

Reportable_Segments_UNITED_DOM2

Reportable Segments (UNITED DOMINION REALTY, L.P.) (Details) (USD $)	3 Months Ended		9 Months Ended		12 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2012	Dec. 31, 2013
	Segments
Segment Reporting Information [Line Items]	'	'	'	'	'	'
Same Store Communities	36,268	'	35,177	'	'	'
Summary of rental income and NOI for UDRs reportable segments and reconciliation of NOI to loss from continuing operations	'	'	'	'	'	'
Reportable apartment home segment rental income	$206,752	$191,124	$608,497	$565,510	'	'
Reportable apartment home segment NOI	-139,814	-128,643	-412,330	'	-382,612	'
Reconciling items:	'	'	'	'	'	'
Property management	-5,599	-5,236	-16,474	'	-15,491	'
Other operating expenses	-2,012	-1,787	-6,118	'	-5,237	'
Real estate depreciation and amortization	89,339	83,738	266,748	251,231	'	'
General and administrative	-11,554	-11,364	-36,078	'	-30,706	'
Casualty (Recoveries)/Charges	0	6,460	-500	12,253	-12,253	'
Interest expense	-33,087	-30,939	-97,662	-92,723	-92,723	'
Gains/(loss) on sales of real estate owned	31,302	0	82,305	0	'	'
Net (income)/loss attributable to noncontrolling interests	4	37	-2	'	30	'
Net income/(loss) attributable to OP unitholders	40,549	3,188	88,917	8,112	8,112	'
Reportable apartment home segment assets:	'	'	'	'	'	'
Total segment assets	8,428,291	'	8,428,291	'	'	8,207,977
Accumulated depreciation	-2,379,033	'	-2,379,033	'	'	-2,208,794
Total segment asset - net book value	6,049,258	'	6,049,258	'	'	5,999,183
Reconciling items:	'	'	'	'	'	'
Cash and cash equivalents	14,605	11,149	14,605	11,149	12,115	30,249
Restricted cash	23,969	'	23,969	'	'	22,796
Deferred financing costs, net	24,344	'	24,344	'	'	26,924
Other assets	117,153	'	117,153	'	'	137,882
Total consolidated assets	6,898,088	'	6,898,088	'	'	6,807,722
Reportable Segment (Textual) [Abstract]	'	'	'	'	'	'
Number of reportable segments	2	'	'	'	'	'
Condition for Community considered to have stabilized occupancy	'	'	'90% occupancy for at least three consecutive months	'	'	'
Percent occupancy to be considered a community	'	'	90.00%	'	'	'
Time to maintain percent occupancy to be considered a community	'	'	'3 months	'	'	'
Number of Tenants or related group of tenants that contributed 10% or more of company total revenue	0	0	0	0	'	'
Same-Store [Member]	'	'	'	'	'	'
Reportable Segment (Textual) [Abstract]	'	'	'	'	'	'
SEC Schedule III, Real Estate, Improvements	15,100	14,500	36,500	'	34,600	'
Same Store Communities Western Region [Member]	'	'	'	'	'	'
Summary of rental income and NOI for UDRs reportable segments and reconciliation of NOI to loss from continuing operations	'	'	'	'	'	'
Reportable apartment home segment rental income	68,275	64,195	189,075	'	177,884	'
Reportable apartment home segment NOI	-49,110	-45,699	-136,587	'	-126,860	'
Reportable apartment home segment assets:	'	'	'	'	'	'
Total segment assets	2,591,838	'	2,591,838	'	'	2,412,091
Same Store Communities Mid-Atlantic Region [Member]	'	'	'	'	'	'
Summary of rental income and NOI for UDRs reportable segments and reconciliation of NOI to loss from continuing operations	'	'	'	'	'	'
Reportable apartment home segment rental income	40,479	40,164	121,356	'	119,937	'
Reportable apartment home segment NOI	-27,622	-27,629	-83,581	'	-83,287	'
Reportable apartment home segment assets:	'	'	'	'	'	'
Total segment assets	1,404,730	'	1,404,730	'	'	1,395,772
Same Store Communities Northeast Region [Member]	'	'	'	'	'	'
Summary of rental income and NOI for UDRs reportable segments and reconciliation of NOI to loss from continuing operations	'	'	'	'	'	'
Reportable apartment home segment rental income	20,721	19,806	45,331	'	43,441	'
Reportable apartment home segment NOI	-15,571	-14,678	-33,361	'	-31,409	'
Reportable apartment home segment assets:	'	'	'	'	'	'
Total segment assets	1,073,905	'	1,073,905	'	'	1,066,260
Same Store Communities Southeastern Region [Member]	'	'	'	'	'	'
Summary of rental income and NOI for UDRs reportable segments and reconciliation of NOI to loss from continuing operations	'	'	'	'	'	'
Reportable apartment home segment rental income	27,210	25,851	80,578	'	76,763	'
Reportable apartment home segment NOI	-17,480	-16,560	-53,329	'	-49,866	'
Reportable apartment home segment assets:	'	'	'	'	'	'
Total segment assets	783,641	'	783,641	'	'	785,134
Same Store Communities Southwestern Region [Member]	'	'	'	'	'	'
Summary of rental income and NOI for UDRs reportable segments and reconciliation of NOI to loss from continuing operations	'	'	'	'	'	'
Reportable apartment home segment rental income	13,859	13,293	40,949	'	39,012	'
Reportable apartment home segment NOI	-8,509	-7,983	-25,130	'	-23,751	'
Reportable apartment home segment assets:	'	'	'	'	'	'
Total segment assets	438,982	'	438,982	'	'	434,875
Non-Mature communities/Other [Member]	'	'	'	'	'	'
Summary of rental income and NOI for UDRs reportable segments and reconciliation of NOI to loss from continuing operations	'	'	'	'	'	'
Reportable apartment home segment rental income	33,064	27,070	121,756	'	106,256	'
Reportable apartment home segment NOI	-21,522	-16,094	-80,342	'	-67,439	'
Reportable apartment home segment assets:	'	'	'	'	'	'
Total segment assets	2,135,195	'	2,135,195	'	'	2,113,845
Reportable Segment (Textual) [Abstract]	'	'	'	'	'	'
SEC Schedule III, Real Estate, Improvements	1,343	1,567	5,001	'	4,800	'
Total Communities [Member]	'	'	'	'	'	'
Summary of rental income and NOI for UDRs reportable segments and reconciliation of NOI to loss from continuing operations	'	'	'	'	'	'
Reportable apartment home segment rental income	203,608	190,379	599,045	'	563,293	'
United Dominion Reality L.P. [Member]	'	'	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'	'	'
Same Store Communities	19,518	'	19,010	'	'	'
Summary of rental income and NOI for UDRs reportable segments and reconciliation of NOI to loss from continuing operations	'	'	'	'	'	'
Reportable apartment home segment NOI	-75,753	-71,993	-223,138	'	-214,573	'
Reconciling items:	'	'	'	'	'	'
Property management	-2,955	-2,860	-8,653	'	-8,436	'
Other operating expenses	-1,484	-1,405	-4,371	'	-4,215	'
Real estate depreciation and amortization	45,043	44,333	134,011	133,962	'	'
General and administrative	-6,939	-6,855	-21,368	'	-18,324	'
Casualty-related (recoveries)/charges, net	0	3,807	'	'	'	'
Casualty (Recoveries)/Charges	0	3,807	-500	8,083	-8,083	'
Interest expense	-10,457	-8,773	-30,629	'	-27,085	'
Gains/(loss) on sales of real estate owned	0	0	40,687	0	'	'
Net (income)/loss attributable to noncontrolling interests	-238	-39	-697	'	-151	'
Net income/(loss) attributable to OP unitholders	8,637	11,011	63,596	28,893	28,893	'
Reportable apartment home segment assets:	'	'	'	'	'	'
Total segment assets	4,219,223	'	4,219,223	'	'	4,188,480
Accumulated depreciation	-1,358,123	'	-1,358,123	'	'	-1,241,574
Total segment asset - net book value	2,861,100	'	2,861,100	'	'	2,946,906
Reconciling items:	'	'	'	'	'	'
Cash and cash equivalents	1,484	2,422	1,484	2,422	2,804	1,897
Restricted cash	13,989	'	13,989	'	'	13,526
Deferred financing costs, net	4,783	'	4,783	'	'	5,848
Other assets	25,070	'	25,070	'	'	25,064
Total consolidated assets	2,906,426	'	2,906,426	'	'	2,993,241
Reportable Segment (Textual) [Abstract]	'	'	'	'	'	'
Number of reportable segments	2	'	'	'	'	'
Number of Tenants or related group of tenants that contributed 10% or more of company total revenue	0	0	0	0	'	'
Related Party Transaction, Management Fee Percentage	'	'	2.75%	'	'	'
United Dominion Reality L.P. [Member] | Same-Store [Member]	'	'	'	'	'	'
Reportable Segment (Textual) [Abstract]	'	'	'	'	'	'
SEC Schedule III, Real Estate, Improvements	8,600	6,900	20,000	'	18,500	'
United Dominion Reality L.P. [Member] | Same Store Communities Western Region [Member]	'	'	'	'	'	'
Summary of rental income and NOI for UDRs reportable segments and reconciliation of NOI to loss from continuing operations	'	'	'	'	'	'
Reportable apartment home segment rental income	49,279	46,246	144,252	'	135,418	'
Reportable apartment home segment NOI	-35,801	-33,307	-105,375	'	-97,533	'
Reportable apartment home segment assets:	'	'	'	'	'	'
Total segment assets	1,742,559	'	1,742,559	'	'	1,733,144
United Dominion Reality L.P. [Member] | Same Store Communities Mid-Atlantic Region [Member]	'	'	'	'	'	'
Summary of rental income and NOI for UDRs reportable segments and reconciliation of NOI to loss from continuing operations	'	'	'	'	'	'
Reportable apartment home segment rental income	17,169	17,105	51,779	'	51,095	'
Reportable apartment home segment NOI	-11,422	-11,483	-34,888	'	-34,689	'
Reportable apartment home segment assets:	'	'	'	'	'	'
Total segment assets	710,277	'	710,277	'	'	706,447
United Dominion Reality L.P. [Member] | Same Store Communities Northeast Region [Member]	'	'	'	'	'	'
Summary of rental income and NOI for UDRs reportable segments and reconciliation of NOI to loss from continuing operations	'	'	'	'	'	'
Reportable apartment home segment rental income	14,968	14,331	28,410	'	27,414	'
Reportable apartment home segment NOI	-11,609	-10,789	-21,448	'	-20,083	'
Reportable apartment home segment assets:	'	'	'	'	'	'
Total segment assets	776,310	'	776,310	'	'	770,937
United Dominion Reality L.P. [Member] | Same Store Communities Southeastern Region [Member]	'	'	'	'	'	'
Summary of rental income and NOI for UDRs reportable segments and reconciliation of NOI to loss from continuing operations	'	'	'	'	'	'
Reportable apartment home segment rental income	11,368	10,841	33,753	'	32,177	'
Reportable apartment home segment NOI	-7,327	-6,957	-22,286	'	-20,898	'
Reportable apartment home segment assets:	'	'	'	'	'	'
Total segment assets	331,727	'	331,727	'	'	328,150
United Dominion Reality L.P. [Member] | Same Store Communities Southwestern Region [Member]	'	'	'	'	'	'
Summary of rental income and NOI for UDRs reportable segments and reconciliation of NOI to loss from continuing operations	'	'	'	'	'	'
Reportable apartment home segment rental income	6,667	6,508	19,873	'	19,098	'
Reportable apartment home segment NOI	-4,192	-4,040	-12,578	'	-11,987	'
Reportable apartment home segment assets:	'	'	'	'	'	'
Total segment assets	227,886	'	227,886	'	'	226,252
United Dominion Reality L.P. [Member] | Non-Mature communities/Other [Member]	'	'	'	'	'	'
Summary of rental income and NOI for UDRs reportable segments and reconciliation of NOI to loss from continuing operations	'	'	'	'	'	'
Reportable apartment home segment rental income	7,993	8,966	36,589	'	41,564	'
Reportable apartment home segment NOI	-5,402	-5,417	-26,563	'	-29,383	'
Reportable apartment home segment assets:	'	'	'	'	'	'
Total segment assets	430,464	'	430,464	'	'	423,550
Reportable Segment (Textual) [Abstract]	'	'	'	'	'	'
SEC Schedule III, Real Estate, Improvements	137	436	555	'	1,497	'
United Dominion Reality L.P. [Member] | Total Communities [Member]	'	'	'	'	'	'
Summary of rental income and NOI for UDRs reportable segments and reconciliation of NOI to loss from continuing operations	'	'	'	'	'	'
Reportable apartment home segment rental income	107,444	103,997	314,656	'	306,766	'
Segment Reconciling Items [Member]	'	'	'	'	'	'
Reconciling items:	'	'	'	'	'	'
Real estate depreciation and amortization	89,339	84,266	266,748	'	252,839	'
Segment Reconciling Items [Member] | United Dominion Reality L.P. [Member]	'	'	'	'	'	'
Reconciling items:	'	'	'	'	'	'
Real estate depreciation and amortization	$45,043	$44,857	$134,011	'	$135,552	'