UDR (UDR) 10-Q 28 Jul 15 2015 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2015	Jul. 27, 2015
Entity Registrant Name	UDR, Inc.
Entity Central Index Key	74,208
Document Type	10-Q
Document Period End Date	Jun. 30, 2015
Amendment Flag	false
Document Fiscal Year Focus	2,015
Document Fiscal Period Focus	Q2
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		259,101,916
United Dominion Reality L.P. [Member]
Entity Registrant Name	United Dominion Realty L.P.
Entity Central Index Key	1,018,254
Document Type	10-Q
Document Period End Date	Jun. 30, 2015
Amendment Flag	false
Document Fiscal Year Focus	2,015
Document Fiscal Period Focus	Q2
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 ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Real estate owned:
Real estate held for investment	$ 8,332,634	$ 8,205,627
Less: accumulated depreciation	(2,557,949)	(2,434,772)
Real Estate Investment Property, Net	5,774,685	5,770,855
Real estate under development (net of accumulated depreciation of $0)	92,645	177,632
Real Estate Investments, Net	5,867,330	5,948,487
Cash and cash equivalents	2,990	15,224
Restricted Cash and Cash Equivalents	22,912	22,340
Deferred financing costs, net	19,930	22,686
Notes receivable, net	15,494	14,369
Investment in and advances to unconsolidated joint ventures, net	914,815	718,226
Other assets	96,259	105,202
Total assets	6,939,730	6,846,534
Liabilities:
Secured debt	1,350,439	1,361,529
Unsecured debt	2,213,964	2,221,576
Real estate taxes payable	18,263	15,978
Accrued interest payable	27,735	34,215
Advance Rent	33,366	34,064
Distributions payable	75,129	69,460
Accounts payable, accrued expenses, and other liabilities	72,054	91,282
Total liabilities	3,790,950	3,828,104
Redeemable noncontrolling interests in the Operating Partnership	290,278	282,480
Equity:
8.00% Series E Cumulative Convertible; 2,803,812 shares and outstanding at June 30, 2015 and December 31, 2014	46,571	46,571
Common stock, $0.01 par value; 350,000,000 shares authorized; 259,091,257 and 255,114,603 shares issued and outstanding at June 30, 2015 and December 31, 2014, respectively	2,591	2,551
Additional Paid in Capital	4,342,829	4,223,747
Distributions in excess of net income	(1,525,159)	(1,528,917)
Accumulated other comprehensive income/(loss), net	(9,190)	(8,855)
Total stockholders' equity	2,857,642	2,735,097
Noncontrolling interests	860	853
Total equity	2,858,502	2,735,950
Total liabilities and equity	$ 6,939,730	$ 6,846,534

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Real estate owned:
Real estate under development accumulated depreciation	$ 0	$ 0
Equity:
Preferred stock, par or stated value per share	$ 0	$ 0
Preferred stock, shares authorized	50,000,000	50,000,000
Preferred stock, shares outstanding	2,803,812	2,803,812
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	350,000,000	350,000,000
Common stock, shares outstanding	259,091,257	255,114,603

Consolidated Statements of Oper

Consolidated Statements of Operations (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
REVENUES
Rental Income	$ 212,764	$ 200,959	$ 419,811	$ 395,311
Joint venture management and other fees	3,098	2,747	15,804	6,434
Total revenues	215,862	203,706	435,615	401,745
OPERATING EXPENSES
Property operating and maintenance	37,194	36,840	74,444	73,560
Real estate taxes and insurance	25,138	23,716	51,360	49,147
Property management	5,851	5,527	11,545	10,872
Other operating expenses	1,769	2,162	3,535	4,088
Real estate depreciation and amortization	90,344	88,876	179,121	177,409
General and administrative	13,721	12,530	25,873	24,524
Casualty-related (recoveries)/charges, net	843	0	1,839	500
Other depreciation and amortization	1,700	1,193	3,323	2,273
Total operating expenses	176,560	170,844	351,040	342,373
Operating income	39,302	32,862	84,575	59,372
Income/(loss) from unconsolidated entities	(573)	(428)	58,586	(3,993)
Interest expense	(29,673)	(31,691)	(58,473)	(64,575)
Interest and other income/(expense), net	382	1,426	742	2,841
Income/(loss) before income taxes, discountinued operations, and gain/(loss) on sale of real estate owned	9,438	2,169	85,430	(6,355)
Tax benefit/(expense), net	1,404	2,190	1,829	5,519
Income/(loss) from continuing operations	10,842	4,359	87,259	(836)
Income/(loss) from discontinued operations, net of tax	0	18	0	(69)
Income/(loss) before gain/(loss) of real estate owned	10,842	4,377	87,259	(905)
Gains/(loss) on sales of real estate, net of tax	79,042	26,709	79,042	51,003
Net income/(loss)	89,884	31,086	166,301	50,098
Net (income)/loss attributable to redeemable noncontrolling interests in the Operating Partnership	(3,029)	(1,077)	(5,617)	(1,724)
Net (income)/loss attributable to noncontrolling interests	0	(2)	(7)	(6)
Net income/(loss) attributable to UDR, Inc.	86,855	30,007	160,677	48,368
Distributions to preferred stockholders - Series E (Convertible)	(931)	(931)	(1,862)	(1,862)
Net (loss)/income attributable to common stockholders	$ 85,924	$ 29,076	$ 158,815	$ 46,506
Income/(loss) per weighted average common share - basic and diluted:
Income/(loss) from continuing operations attributable to common stockholders	$ 0.33	$ 0.12	$ 0.62	$ 0.19
Income/(loss) from discontinued operations attributable to common stockholders,	0	0	0	0
Net income/(loss) attributable to common stockholders	$ 0.33	$ 0.12	$ 0.62	$ 0.19
Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements	4,957	1,936	1,923	1,875
Income/(loss) from continuing operations attributable to common stockholders,	$ 0.33	$ 0.12	$ 0.61	$ 0.18
Income from discontinued operations attributable to common stockholders	0	0	0	0
Net income/(loss) attributable to common stockholders	0.33	0.12	0.61	0.18
Common distributions declared per share	$ 0.2775	$ 0.2600	$ 0.5550	$ 0.5200
Weighted average number of common shares outstanding — basic	257,849	250,255	257,344	250,216
Weighted average number of common shares outstanding — diluted	262,806	252,191	259,267	252,091

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income / (Loss) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Net income/(loss)	$ 89,884	$ 31,086	$ 166,301	$ 50,098
Other comprehensive income/(loss), including portion attributable to noncontrolling interests:
Unrealized holding gain/(loss)	6,186	304	(1,366)	249
(Gain)/loss reclassified into earnings from other comprehensive income/(loss)	292	1,145	1,029	2,677
Other comprehensive income/(loss), including portion attributable to noncontrolling interests	6,478	1,449	(337)	2,926
Comprehensive income/(loss)	96,362	32,535	165,964	53,024
Comprehensive (income)/loss attributable to noncontrolling interests	(3,253)	(1,129)	(5,623)	(1,836)
Comprehensive income/(loss) attributable to UDR, Inc.	$ 93,109	$ 31,406	$ 160,341	$ 51,188

Consolidated Statements of Chan

Consolidated Statements of Changes in Equity (Unaudited) - 6 months ended Jun. 30, 2015 - USD ($) $ in Thousands	Total	Preferred Stock [Member]	Common Stock [Member]	Paid - in Capital	Distributions in Excess of Net Income	Accumulated Other Comprehensive Income/(Loss)	Noncontrolling Interest [Member]
Beginning Balance, Shares at Dec. 31, 2014		2,803,812	255,114,603
Beginning Balance at Dec. 31, 2014	$ 2,735,950	$ 46,571	$ 2,551	$ 4,223,747	$ (1,528,917)	$ (8,855)	$ 853
Consolidted Statements of Changes in Equity
Net income/(loss) attributable to UDR, Inc.	160,677				160,677
Net income/(loss) attributable to noncontrolling interests	7						7
Other comprehensive income/(loss)	(335)					(335)
Issuance/(forfeiture) of common and restricted shares, net Shares			(434,234)
Issuance/(forfeitures) of common and restricted shares, net	6,885		$ 4	6,881
Issuance of common shares through public offering	108,739		$ 34	108,705
Stock Redeemed or Called During Period, Shares		0
Stock Redeemed or Called During Period, Value		$ 0			0
Stock Issued During Period, Shares, New Issues			3,439,636
Stock Issued During Period, Shares, Conversion of Units			102,784
Adjustment for conversion of noncontrolling interest of unitholders in Operating Partnership	3,498		$ (2)	(3,496)
Common stock distributions declared ($0.555 per share)	(144,127)				144,127
Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests							0
Preferred stock distributions declared-Series E ($0.6644 per share)	(1,862)				1,862
Adjustment to reflect redemption value of redeemable noncontrolling interests	(10,930)				(10,930)
Ending Balance at Jun. 30, 2015	$ 2,858,502	$ 46,571	$ 2,591	$ 4,342,829	$ (1,525,159)	$ (9,190)	$ 860
Ending Balance, Shares at Jun. 30, 2015		2,803,812	259,091,257

Consolidated Statements of Cha7

Consolidated Statements of Changes in Equity (Unaudited) (Parenthetical) - $ / shares	6 Months Ended
	Jun. 30, 2015
Common distributions declared per share	$ 0.5550
Series E Preferred Stock [Member]
Preferred stock distributions declared	$ 0.6644

Consolidated Statements of Cash

Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Operating Activities
Net income/(loss)	$ 166,301	$ 50,098
Adjustments to reconcile net income/(loss) to net cash provided by operating activities:
Depreciation and amortization	182,444	179,682
Gain on sale of real estate owned, net of tax	(79,042)	(51,003)
Tax (benefit)/provision, net	(1,829)	(5,559)
Income/(loss) from unconsolidated entities	(58,586)	3,993
Casualty-related (recoveries)/charges, net	1,839	500
Other	13,154	13,054
Changes in operating assets and liabilities:
(Increase)/decrease in operating assets	7,431	5,677
Increase/(decrease) in operating liabilities	(14,709)	(10,229)
Net cash provided by operating activities	217,003	186,213
Investing Activities
Acquisition of real estate assets	0	(77,793)
Proceeds from sales of real estate investments, net	90,543	47,922
Development of real estate assets	(66,083)	(115,964)
Capital expenditures and other major improvements - real estate assets, net of escrow reimbursement	(47,453)	(57,574)
Capital expenditures - non-real estate assets	(1,655)	(2,917)
Investment in unconsolidated joint ventures	(184,078)	(120,555)
Distributions received from unconsolidated joint venture	46,075	12,507
Purchase deposits on pending acquisitions	0	(4,000)
(Issuance)/repayment of notes receivable	(1,125)	38,800
Net cash provided by/(used in) investing activities	(163,776)	(279,574)
Financing Activities
Payments on secured debt	(4,549)	(42,304)
Proceeds from the issuance of secured debt	0	5,502
Payments on unsecured debt	(325,319)	(312,500)
Proceeds from Issuance of Unsecured Debt	0	298,956
Net proceeds/(repayment) of revolving bank debt	304,500	276,500
Proceeds from the issuance of common shares through public offering, net	108,739	0
Distributions paid to redeemable noncontrolling interests	(5,148)	(4,909)
Distributions paid to preferred stockholders	(1,862)	(1,862)
Distributions paid to common stockholders	(138,559)	(124,338)
Other	(3,263)	(5,117)
Net cash provided by/(used in) financing activities	(65,461)	89,928
Net increase/(decrease) in cash and cash equivalents	(12,234)	(3,433)
Cash and cash equivalents, beginning of period	15,224	30,249
Cash and cash equivalents, end of period	2,990	26,816
Supplemental Information:
Interest paid during the period, net of amounts capitalized	66,448	69,291
Non-cash transactions:
Acquisition of real estate	24,067	0
Fair value adjustment of debt acquired as part of acquisition of real estate	$ 1,363	$ 0

Consolidated Balance Sheets (UN

Consolidated Balance Sheets (UNITED DOMINION REALTY, L.P) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Real estate owned:
Real estate held for investment	$ 8,332,634	$ 8,205,627
Less: accumulated depreciation	(2,557,949)	(2,434,772)
Real estate under development (net of accumulated depreciation of $0 and $0, respectively)	92,645	177,632
Total real estate owned, net of accumulated depreciation	5,867,330	5,948,487
Cash and cash equivalents	2,990	15,224
Deferred financing costs, net	19,930	22,686
Other assets	96,259	105,202
Total assets	6,939,730	6,846,534
LIABILITIES AND CAPITAL
Secured debt	1,350,439	1,361,529
Real estate taxes payable	18,263	15,978
Accrued interest payable	27,735	34,215
Distributions payable	75,129	69,460
Deferred gains on the sale of depreciable property	6,800	28,500
Accounts payable, accrued expenses, and other liabilities	72,054	91,282
Total liabilities	3,790,950	3,828,104
Partners' Capital:
Accumulated other comprehensive income/(loss), net	(9,190)	(8,855)
Total liabilities and equity	6,939,730	6,846,534
United Dominion Reality L.P. [Member]
Real estate owned:
Real estate held for investment	4,238,995	4,238,770
Less: accumulated depreciation	(1,474,834)	(1,403,303)
Total real estate owned, net of accumulated depreciation	2,764,161	2,835,467
Cash and cash equivalents	164	502
Restricted Cash	14,456	13,811
Deferred financing costs, net	3,707	4,475
Other assets	23,090	24,029
Total assets	2,805,578	2,878,284
LIABILITIES AND CAPITAL
Secured debt	912,567	931,959
Notes payable due to General Partner	88,696	88,696
Real estate taxes payable	7,516	7,061
Accrued interest payable	3,168	3,284
Security deposits and prepaid rent	17,905	18,387
Distributions payable	50,962	47,788
Deferred gains on the sale of depreciable property	0	24,622
Accounts payable, accrued expenses, and other liabilities	18,362	22,436
Total liabilities	$ 1,099,176	$ 1,144,233
Commitments and contingencies (Note 11)
Partners' Capital:
General partner: 110,883 OP Units outstanding at June 30, 2015 and December 31, 2014	$ 1,094	$ 1,105
Limited partners: 183,167,815 OP Units outstanding at June 30, 2015 and December 31, 2014	1,684,784	1,702,971
Accumulated other comprehensive income/(loss), net	(599)	(1,075)
Total partners' capital	1,685,279	1,703,001
Advances (to)/from General Partner	2,956	13,624
Noncontrolling interests	18,167	17,426
Total capital	1,706,402	1,734,051
Total liabilities and equity	$ 2,805,578	$ 2,878,284

Consolidated Balance Sheets (10

Consolidated Balance Sheets (UNITED DOMINION REALTY, L.P) (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Real estate under development accumulated depreciation	$ 0	$ 0
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 Op11

Consolidated Statements of Operations (Unaudited) (UNITED DOMINION REALTY, L.P) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
OPERATING EXPENSES
Property operating and maintenance	$ 37,194	$ 36,840	$ 74,444	$ 73,560
Real estate taxes and insurance	25,138	23,716	51,360	49,147
Property management	5,851	5,527	11,545	10,872
Other operating expenses	1,769	2,162	3,535	4,088
General and administrative	13,721	12,530	25,873	24,524
Casualty-related (recoveries)/charges, net	843	0	1,839	500
Total operating expenses	176,560	170,844	351,040	342,373
Operating income	39,302	32,862	84,575	59,372
Interest and other income/(expense), net	382	1,426	742	2,841
Income/(loss) from continuing operations	10,842	4,359	87,259	(836)
Income/(loss) from discontinued operations, net of tax	0	18	0	(69)
Gains/(loss) on sales of real estate owned	79,042	26,709	79,042	51,003
Net income/(loss)	89,884	31,086	166,301	50,098
Net (income)/loss attributable to noncontrolling interests	(3,253)	(1,129)	(5,623)	(1,836)
Net (income)/loss attributable to noncontrolling interests			(7)
Net income/(loss) attributable to OP unitholders	86,855	30,007	160,677	48,368
United Dominion Reality L.P. [Member]
REVENUES
Rental income	113,158	104,842	223,253	207,212
OPERATING EXPENSES
Property operating and maintenance	19,065	18,328	38,179	36,562
Real estate taxes and insurance	11,810	11,546	24,676	23,265
Property management	3,112	2,883	6,139	5,698
Other operating expenses	1,496	1,451	2,986	2,887
Real estate depreciation and amortization	44,100	44,697	88,578	88,968
General and administrative	7,032	7,459	12,671	14,429
Casualty-related (recoveries)/charges, net	280	0	873	500
Total operating expenses	86,895	86,364	174,102	172,309
Operating income	26,263	18,478	49,151	34,903
Interest expense	(9,757)	(9,008)	(19,377)	(17,871)
Interest expense on note payable due to General Partner	(1,151)	(1,151)	(2,302)	(2,302)
Income/(loss) before gain/(loss) of real estate owned	15,355	8,319	27,472	14,730
Gains/(loss) on sales of real estate owned	32,375	16,285	56,998	40,687
Net income/(loss)	47,730	24,604	84,470	55,417
Net (income)/loss attributable to noncontrolling interests	(347)	(178)	(741)	(458)
Net income/(loss) attributable to OP unitholders	$ 47,383	$ 24,426	$ 83,729	$ 54,959
Income/(loss) per OP unit- basic and diluted:
Net income/(loss) attributable to OP unitholders (in dollars per share)	$ 0.26	$ 0.13	$ 0.46	$ 0.30
Weighted average OP units outstanding - basic and diluted	183,279	183,279	183,279	183,279

Consolidated Statements of Co12

Consolidated Statements of Comprehensive Income / (Loss) (UNITED DOMINION REALTY, L.P.) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Net income/(loss)	$ 89,884	$ 31,086	$ 166,301	$ 50,098
Other comprehensive income/(loss), including portion attributable to noncontrolling interests:
Unrealized holding gain/(loss)	6,186	304	(1,366)	249
Other comprehensive income/(loss), including portion attributable to noncontrolling interests	6,478	1,449	(337)	2,926
Comprehensive income/(loss)	96,362	32,535	165,964	53,024
Comprehensive (income)/loss attributable to noncontrolling interests	(3,253)	(1,129)	(5,623)	(1,836)
Comprehensive income/(loss) attributable to OP unitholders	93,109	31,406	160,341	51,188
United Dominion Reality L.P. [Member]
Net income/(loss)	47,730	24,604	84,470	55,417
Other comprehensive income/(loss), including portion attributable to noncontrolling interests:
Unrealized holding gain/(loss)	(26)	(140)	(77)	(191)
(Gain)/loss reclassifed into earnings from other comprehensive income/(loss)	267	573	553	1,196
Other comprehensive income/(loss), including portion attributable to noncontrolling interests	241	433	476	1,005
Comprehensive income/(loss)	47,971	25,037	84,946	56,422
Comprehensive (income)/loss attributable to noncontrolling interests	(347)	(178)	(741)	(458)
Comprehensive income/(loss) attributable to OP unitholders	$ 47,624	$ 24,859	$ 84,205	$ 55,964

Consolidated Statements of Ch13

Consolidated Statements of Changes in Capital (UNITED DOMINION REALTY, L.P) (Unaudited) - United Dominion Reality L.P. [Member] - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2015
Balance, December 31, 2014		$ 1,734,051
Advances (to)/from General Partner	$ (2,956)	(2,956)
Net income/(loss)		84,470
Distributions		101,927
OP Unit Redemptions for common shares of UDR	0
Adjustment to reflect limited partners' capital at redemption value	0
Unrealized Gain (Loss) on Derivatives		476
Net change in amount due to/(from) General Partner		(10,668)
Balance, June 30, 2015	1,706,402	1,706,402
Payable/(Receivable) due to/(from) General Partner [Member] [Member]
Net change in amount due to/(from) General Partner		(10,668)
Accumulated Other Comprehensive Income (Loss) [Member]
Balance, December 31, 2014		(1,075)
Unrealized Gain (Loss) on Derivatives		476
Balance, June 30, 2015	(599)	(599)
Partnership Capital [Member]
Balance, December 31, 2014		1,703,001
Net income/(loss)		83,729
Distributions		101,927
Adjustment to reflect limited partners' capital at redemption value	0
Balance, June 30, 2015	1,685,279	1,685,279
Noncontrolling Interest [Member]
Balance, December 31, 2014		17,426
Net income/(loss)		741
Balance, June 30, 2015	18,167	18,167
Partnership Capital [Member]
OP Unit Redemptions for common shares of UDR	0
Unrealized Gain (Loss) on Derivatives		476
Class A Limited Partner [Member]
Balance, December 31, 2014		53,987
Net income/(loss)		868
Distributions		(1,164)
Adjustment to reflect limited partners' capital at redemption value		2,415
Balance, June 30, 2015	56,106	56,106
Limited Partners [Member]
Balance, December 31, 2014		228,493
Net income/(loss)		3,357
Distributions		(4,086)
OP Unit Redemptions for common shares of UDR		(3,496)
Adjustment to reflect limited partners' capital at redemption value		9,905
Balance, June 30, 2015	234,173	234,173
Limited Partner [Member]
Balance, December 31, 2014		1,420,491
Net income/(loss)		79,453
Distributions		(96,615)
OP Unit Redemptions for common shares of UDR		3,496
Adjustment to reflect limited partners' capital at redemption value		(12,320)
Balance, June 30, 2015	1,394,505	1,394,505
General Partner [Member]
Balance, December 31, 2014		1,105
Net income/(loss)		51
Distributions		(62)
Balance, June 30, 2015	$ 1,094	$ 1,094

Consolidated Statements of Ca14

Consolidated Statements of Cash Flows (UNITED DOMINION REALTY, L.P) (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Operating Activities
Net income/(loss)	$ 166,301	$ 50,098
Adjustments to reconcile net income/(loss) to net cash provided by operating activities:
Depreciation and amortization	182,444	179,682
Gain/(loss) on sale of real estate owned	(79,042)	(51,003)
Casualty-related (recoveries)/charges, net	1,839	500
Other	13,154	13,054
Changes in operating assets and liabilities:
(Increase)/decrease in operating assets	7,431	5,677
Increase/(decrease) in operating liabilities	(14,709)	(10,229)
Net cash provided by operating activities	217,003	186,213
Investing Activities
Development of real estate assets	(66,083)	(115,964)
Capital expenditures and other major improvements - real estate assets, net of escrow reimbursement	(47,453)	(57,574)
Net cash provided by/(used in) investing activities	(163,776)	(279,574)
Financing Activities
Proceeds from the issuance of secured debt	0	5,502
Payments on secured debt	(4,549)	(42,304)
Net cash provided by/(used in) financing activities	(65,461)	89,928
Net increase/(decrease) in cash and cash equivalents	(12,234)	(3,433)
Cash and cash equivalents, beginning of period	15,224	30,249
Cash and cash equivalents, end of period	2,990	26,816
Supplemental Information:
Interest paid during the period, net of amounts capitalized	66,448	69,291
United Dominion Reality L.P. [Member]
Operating Activities
Net income/(loss)	84,470	55,417
Adjustments to reconcile net income/(loss) to net cash provided by operating activities:
Depreciation and amortization	88,578	88,968
Gain/(loss) on sale of real estate owned	(56,998)	(40,687)
Casualty-related (recoveries)/charges, net	873	500
Other	(349)	(123)
Changes in operating assets and liabilities:
(Increase)/decrease in operating assets	(341)	1,506
Increase/(decrease) in operating liabilities	(976)	(2,164)
Net cash provided by operating activities	115,257	103,417
Investing Activities
Proceeds from sale of real estate investments, net	27,718	47,922
Development of real estate assets	(7,740)	(29,192)
Capital expenditures and other major improvements - real estate assets, net of escrow reimbursement	(25,487)	(21,355)
Net cash provided by/(used in) investing activities	(5,509)	(2,625)
Financing Activities
Advances from/(to) General Partner, net	(102,378)	(94,113)
Proceeds from the issuance of secured debt	0	0
Payments on secured debt	(2,588)	(2,492)
Distributions paid to partnership unitholders	(5,120)	(4,909)
Payments of financing costs	0	0
Net cash provided by/(used in) financing activities	(110,086)	(101,514)
Net increase/(decrease) in cash and cash equivalents	(338)	(722)
Cash and cash equivalents, beginning of period	502	1,897
Cash and cash equivalents, end of period	164	1,175
Supplemental Information:
Interest paid during the period, net of amounts capitalized	$ 23,296	$ 21,649

Consolidation and Basis of Pres

Consolidation and Basis of Presentation	6 Months Ended
	Jun. 30, 2015
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 June 30, 2015 , there were 183,278,698 units in the Operating Partnership outstanding, of which 174,216,009 units, or 95.1% , were owned by UDR and 9,062,689 units, or 4.9% , 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 June 30, 2015 , and results of operations for the three and six months ended June 30, 2015 and 2014 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, 2014 appearing in UDR’s Annual Report on Form 10-K, filed with the Securities and Exchange Commission on February 24, 2015 . 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 Pr16

Consolidation and Basis of Presentation (UNITED DOMINION REALTY, L.P.)	6 Months Ended
	Jun. 30, 2015
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 June 30, 2015 , there were 183,278,698 units in the Operating Partnership outstanding, of which 174,216,009 units, or 95.1% , were owned by UDR and 9,062,689 units, or 4.9% , 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 June 30, 2015 , and results of operations for the three and six months ended June 30, 2015 and 2014 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, 2014 appearing in UDR’s Annual Report on Form 10-K, filed with the Securities and Exchange Commission on February 24, 2015 . 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 months ended June 30, 2015 and 2014 , rental revenues of the Operating Partnership represented 53% and 52% , respectively, and for the six months ended June 30, 2015 and 2014 53% and 52% , respectively, of the General Partner’s consolidated rental revenues. As of June 30, 2015 , the Operating Partnership’s apartment portfolio consisted of 67 communities located in 17 markets consisting of 20,569 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 June 30, 2015 , there were 183,278,698 OP Units outstanding, of which 174,216,009 or 95.1% were owned by UDR and affiliated entities and 9,062,689 or 4.9% were owned by non-affiliated limited partners. See Note 8, 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 June 30, 2015 , and results of operations for the three and six months ended June 30, 2015 and 2014 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 June 30, 2015 included in the Annual Report on Form 10-K filed by UDR and the Operating Partnership with the SEC on February 24, 2015 . 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 Policies

Significant Accounting Policies	6 Months Ended
	Jun. 30, 2015
Accounting Policies [Abstract]
SIGNIFICANT ACCOUNTING POLICIES	SIGNIFICANT ACCOUNTING POLICIES Recent Accounting Pronouncements In May 2014, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("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, 2018; early adoption is permitted on January 1, 2017. 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. In April 2015, the FASB issued ASU 2015-03, Simplifying the Presentation of Debt Issuance Costs, to revise the presentation of debt issuance costs. Under ASU 2015-03, entities will present debt issuance costs in their balance sheet as a direct deduction from the related debt liability rather than as an asset. Amortization of the deferred costs will continue to be included in interest expense. The guidance, which is to be applied retrospectively to all prior periods, is effective for fiscal years beginning after December 15, 2015, with early adoption permitted for financial statements that have not been previously issued. The Company does not expect ASU 2015-03 to have a significant effect on its consolidated financial statements. In February 2015, the FASB issued ASU 2015-02, Amendments to the Consolidation Analysis, which makes changes to both the variable interest model and the voting model. Among other changes, the new standard specifically eliminates the presumption in the current voting model that a general partner controls a limited partnership or similar entity unless that presumption can be overcome. The new standard will be effective for the Company beginning on January 1, 2016 and early adoption is permitted, including adoption in an interim period. The new standard must be applied using a modified retrospective approach by recording a cumulative-effect adjustment to equity/capital as of the beginning of the period of adoption or retrospectively to each period presented. The Company is currently evaluating the impact of adopting the new standard on its consolidated financial statements. Discontinued Operations In accordance with GAAP, 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. We record sales of real estate that do not meet the definition of a discontinued operation in Gain/(loss) on sale of real estate owned, net of tax on the Consolidated Statements of Operations. 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 June 30, 2015 and December 31, 2014 ( dollars in thousands): Interest rate at Balance outstanding June 30, June 30, December 31, 2014 Note due February 2017 (a) 10.00 % $ 12,994 $ 11,869 Note due July 2017 (b) 8.00 % 2,500 2,500 Total notes receivable, net $ 15,494 $ 14,369 (a) The Company has a secured note receivable with an unaffiliated third party with an aggregate commitment of $13.0 million . During the six months ended June 30, 2015 , 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 (February 2017). (b) The Company has a secured note receivable with an unaffiliated third party with an aggregate commitment of $2.5 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). The Company recognized $0.3 million and $1.3 million of interest income from notes receivable during the three months ended June 30, 2015 and 2014 , respectively, and $0.7 million and $2.5 million during the six months ended June 30, 2015 and 2014 , respectively, none of which was related party interest income. Interest income is included in Interest income 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 six months ended June 30, 2015 and 2014 , 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 $224,000 and $50,000 during the three months ended June 30, 2015 and 2014 , respectively, and $(1,000) and $106,000 during the six months ended June 30, 2015 and 2014 , 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 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 June 30, 2015 , UDR’s net deferred tax asset was $9.1 million (net of a valuation allowance of less than $0.1 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 June 30, 2015 . UDR and its subsidiaries are subject to federal income tax as well as income tax of various state and local jurisdictions. The tax years 2011 through 2014 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 Polici18

Significant Accounting Policies (UNITED DOMINION REALTY, L.P.)	6 Months Ended
	Jun. 30, 2015
Entity Information [Line Items]
SIGNIFICANT ACCOUNTING POLICIES	SIGNIFICANT ACCOUNTING POLICIES Recent Accounting Pronouncements In May 2014, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("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, 2018; early adoption is permitted on January 1, 2017. 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. In April 2015, the FASB issued ASU 2015-03, Simplifying the Presentation of Debt Issuance Costs, to revise the presentation of debt issuance costs. Under ASU 2015-03, entities will present debt issuance costs in their balance sheet as a direct deduction from the related debt liability rather than as an asset. Amortization of the deferred costs will continue to be included in interest expense. The guidance, which is to be applied retrospectively to all prior periods, is effective for fiscal years beginning after December 15, 2015, with early adoption permitted for financial statements that have not been previously issued. The Company does not expect ASU 2015-03 to have a significant effect on its consolidated financial statements. In February 2015, the FASB issued ASU 2015-02, Amendments to the Consolidation Analysis, which makes changes to both the variable interest model and the voting model. Among other changes, the new standard specifically eliminates the presumption in the current voting model that a general partner controls a limited partnership or similar entity unless that presumption can be overcome. The new standard will be effective for the Company beginning on January 1, 2016 and early adoption is permitted, including adoption in an interim period. The new standard must be applied using a modified retrospective approach by recording a cumulative-effect adjustment to equity/capital as of the beginning of the period of adoption or retrospectively to each period presented. The Company is currently evaluating the impact of adopting the new standard on its consolidated financial statements. Discontinued Operations In accordance with GAAP, 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. We record sales of real estate that do not meet the definition of a discontinued operation in Gain/(loss) on sale of real estate owned, net of tax on the Consolidated Statements of Operations. 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 June 30, 2015 and December 31, 2014 ( dollars in thousands): Interest rate at Balance outstanding June 30, June 30, December 31, 2014 Note due February 2017 (a) 10.00 % $ 12,994 $ 11,869 Note due July 2017 (b) 8.00 % 2,500 2,500 Total notes receivable, net $ 15,494 $ 14,369 (a) The Company has a secured note receivable with an unaffiliated third party with an aggregate commitment of $13.0 million . During the six months ended June 30, 2015 , 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 (February 2017). (b) The Company has a secured note receivable with an unaffiliated third party with an aggregate commitment of $2.5 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). The Company recognized $0.3 million and $1.3 million of interest income from notes receivable during the three months ended June 30, 2015 and 2014 , respectively, and $0.7 million and $2.5 million during the six months ended June 30, 2015 and 2014 , respectively, none of which was related party interest income. Interest income is included in Interest income 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 six months ended June 30, 2015 and 2014 , 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 $224,000 and $50,000 during the three months ended June 30, 2015 and 2014 , respectively, and $(1,000) and $106,000 during the six months ended June 30, 2015 and 2014 , 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 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 June 30, 2015 , UDR’s net deferred tax asset was $9.1 million (net of a valuation allowance of less than $0.1 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 June 30, 2015 . UDR and its subsidiaries are subject to federal income tax as well as income tax of various state and local jurisdictions. The tax years 2011 through 2014 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 May 2014, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("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, 2018; early adoption is permitted on January 1, 2017. The Operating Partnership 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. In April 2015, the FASB issued ASU 2015-03, Simplifying the Presentation of Debt Issuance Costs, to revise the presentation of debt issuance costs. Under ASU 2015-03, entities will present debt issuance costs in their balance sheet as a direct deduction from the related debt liability rather than as an asset. Amortization of the deferred costs will continue to be included in interest expense. The guidance, which is to be applied retrospectively to all prior periods, is effective for fiscal years beginning after December 15, 2015, with early adoption permitted for financial statements that have not been previously issued. The Operating Partnership does not expect ASU 2015-03 to have a significant effect on its consolidated financial statements. In February 2015, the FASB issued ASU 2015-02, Amendments to the Consolidation Analysis, which makes changes to both the variable interest model and the voting model. Among other changes, the new standard specifically eliminates the presumption in the current voting model that a general partner controls a limited partnership or similar entity unless that presumption can be overcome. The new standard will be effective for the Operating Partnership beginning on January 1, 2016 and early adoption is permitted, including adoption in an interim period. The new standard must be applied using a modified retrospective approach by recording a cumulative-effect adjustment to equity/capital as of the beginning of the period of adoption or retrospectively to each period presented. The Operating Partnership is currently evaluating the impact of adopting the new standard on its consolidated financial statements. Discontinued Operations In accordance with GAAP, 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. We record sales of real estate that do not meet the definition of a discontinued operation in Gain/(loss) on sale of real estate owned, net of tax on the Consolidated Statements of Operations. Income/(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 outstanding during the year. 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. 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 six months ended June 30, 2015 and 2014 , 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 7, 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 ( 2011 through 2014 ) 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	6 Months Ended
	Jun. 30, 2015
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 June 30, 2015 , the Company owned and consolidated 136 communities in 10 states plus the District of Columbia totaling 39,404 apartment homes. The following table summarizes the carrying amounts for our real estate owned (at cost) as of June 30, 2015 and December 31, 2014 (dollars in thousands): June 30, December 31, 2014 Land and land improvements $ 1,919,597 $ 1,980,221 Depreciable property — held and used: Building, improvements, and furniture, fixtures and equipment 6,413,037 6,225,406 Under development: Land and land improvements 78,085 24,584 Building, improvements, and furniture, fixtures and equipment 14,560 153,048 Real estate owned 8,425,279 8,383,259 Accumulated depreciation (2,557,949 ) (2,434,772 ) Real estate owned, net $ 5,867,330 $ 5,948,487 In February 2015, the Company acquired an office building in Highlands Ranch, Colorado, for total consideration of approximately $24.0 million , which was comprised of assumed debt. The Company's corporate offices, as well as other leased office space, are located in the acquired building. The building consists of approximately 120,000 square feet, of which UDR occupies approximately 44,000 square feet. All existing leases were assumed by the Company at the time of acquisition. During the six months ended June 30, 2015 , the Company sold three communities with a total of 812 apartment homes for gross proceeds of $109.9 million , resulting in net proceeds of $90.5 million and a total gain, net of tax, of $79.0 million . A portion of the sale proceeds were designated as a tax-deferred exchange related to a 2014 acquisition under Section 1031 of the Internal Revenue Code. In June 2015, the Company and the Operating Partnership entered into a definitive agreement with an affiliate of Lone Star Funds (“Lone Star”) and Home Properties, L.P. (“Home”) to acquire up to six communities valued at $908.0 million in exchange for a combination of partnership units of a newly formed operating partnership ("UDR DownREIT Units"), cash and the assumption of debt. The agreement provides that each Home unitholder will have the option to elect to receive cash from Lone Star, UDR DownREIT Units, or a combination of cash and UDR DownREIT Units. The number of UDR DownREIT Units and the amount of cash will be determined at the closing of the consent solicitation of the Home unitholders, which we anticipate to be completed by mid-August, 2015. If all Home unitholders elect to receive UDR DownREIT Units, the transaction would be funded through the issuance of approximately $753.0 million of UDR DownREIT Units at $35 per unit, the assumption of $90.0 million of debt and $65.0 million in cash, inclusive of transfer taxes and loan assumption fees. Based upon the level of Home unitholders electing to receive UDR DownREIT Units, UDR will have the option to either acquire less than six properties or to acquire some of the properties through a Section 1031 exchange pursuant to the Internal Revenue Code. The closing of the transaction is subject to certain customary closing conditions, including, among others, the satisfaction (or waiver) of certain closing conditions to the merger between Lone Star and Home, and is anticipated to occur during the fourth quarter of 2015. 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 $1.6 million and $2.1 million for the three months ended June 30, 2015 and 2014 , respectively, and $3.8 million and $5.5 million for the six months ended June 30, 2015 and 2014 , respectively. Total interest capitalized was $3.8 million and $4.9 million for the three months ended June 30, 2015 and 2014 , respectively, and $8.6 million and $10.2 million for the six months ended June 30, 2015 and 2014 , 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.

Real Estate Owned (UNITED DOMIN

Real Estate Owned (UNITED DOMINION REALTY, L.P.)	6 Months Ended
	Jun. 30, 2015
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 June 30, 2015 , the Company owned and consolidated 136 communities in 10 states plus the District of Columbia totaling 39,404 apartment homes. The following table summarizes the carrying amounts for our real estate owned (at cost) as of June 30, 2015 and December 31, 2014 (dollars in thousands): June 30, December 31, 2014 Land and land improvements $ 1,919,597 $ 1,980,221 Depreciable property — held and used: Building, improvements, and furniture, fixtures and equipment 6,413,037 6,225,406 Under development: Land and land improvements 78,085 24,584 Building, improvements, and furniture, fixtures and equipment 14,560 153,048 Real estate owned 8,425,279 8,383,259 Accumulated depreciation (2,557,949 ) (2,434,772 ) Real estate owned, net $ 5,867,330 $ 5,948,487 In February 2015, the Company acquired an office building in Highlands Ranch, Colorado, for total consideration of approximately $24.0 million , which was comprised of assumed debt. The Company's corporate offices, as well as other leased office space, are located in the acquired building. The building consists of approximately 120,000 square feet, of which UDR occupies approximately 44,000 square feet. All existing leases were assumed by the Company at the time of acquisition. During the six months ended June 30, 2015 , the Company sold three communities with a total of 812 apartment homes for gross proceeds of $109.9 million , resulting in net proceeds of $90.5 million and a total gain, net of tax, of $79.0 million . A portion of the sale proceeds were designated as a tax-deferred exchange related to a 2014 acquisition under Section 1031 of the Internal Revenue Code. In June 2015, the Company and the Operating Partnership entered into a definitive agreement with an affiliate of Lone Star Funds (“Lone Star”) and Home Properties, L.P. (“Home”) to acquire up to six communities valued at $908.0 million in exchange for a combination of partnership units of a newly formed operating partnership ("UDR DownREIT Units"), cash and the assumption of debt. The agreement provides that each Home unitholder will have the option to elect to receive cash from Lone Star, UDR DownREIT Units, or a combination of cash and UDR DownREIT Units. The number of UDR DownREIT Units and the amount of cash will be determined at the closing of the consent solicitation of the Home unitholders, which we anticipate to be completed by mid-August, 2015. If all Home unitholders elect to receive UDR DownREIT Units, the transaction would be funded through the issuance of approximately $753.0 million of UDR DownREIT Units at $35 per unit, the assumption of $90.0 million of debt and $65.0 million in cash, inclusive of transfer taxes and loan assumption fees. Based upon the level of Home unitholders electing to receive UDR DownREIT Units, UDR will have the option to either acquire less than six properties or to acquire some of the properties through a Section 1031 exchange pursuant to the Internal Revenue Code. The closing of the transaction is subject to certain customary closing conditions, including, among others, the satisfaction (or waiver) of certain closing conditions to the merger between Lone Star and Home, and is anticipated to occur during the fourth quarter of 2015. 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 $1.6 million and $2.1 million for the three months ended June 30, 2015 and 2014 , respectively, and $3.8 million and $5.5 million for the six months ended June 30, 2015 and 2014 , respectively. Total interest capitalized was $3.8 million and $4.9 million for the three months ended June 30, 2015 and 2014 , respectively, and $8.6 million and $10.2 million for the six months ended June 30, 2015 and 2014 , 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.
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 June 30, 2015 , the Operating Partnership owned and consolidated 67 communities in nine states plus the District of Columbia totaling 20,569 apartment homes. The following table summarizes the carrying amounts for our real estate owned (at cost) as of June 30, 2015 and December 31, 2014 (dollars in thousands) : June 30, December 31, 2014 Land $ 1,006,651 $ 1,008,014 Depreciable property — held and used: Buildings, improvements, and furniture, fixture and equipment 3,232,344 3,230,756 Real estate owned 4,238,995 4,238,770 Accumulated depreciation (1,474,834 ) (1,403,303 ) Real estate owned, net $ 2,764,161 $ 2,835,467 The Operating Partnership did not have any acquisitions or real estate sales during the six months ended June 30, 2015 . During the six months ended June 30, 2015 , the Operating Partnership sold one community with a total of 240 apartment homes for gross proceeds of $45.3 million , resulting in net proceeds of $27.7 million and a total gain, net of tax, of $32.4 million . Additionally, the Operating Partnership recognized a gain of $24.6 million , which was previously deferred, in connection with the sale of the communities held by the Texas Joint Venture. 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 $195,000 and $542,000 for the three months ended June 30, 2015 and 2014 , respectively, and $328,000 and $1.3 million for the six months ended June 30, 2015 and 2014 , respectively. Total interest capitalized was $32,000 and $1.0 million during the three months ended June 30, 2015 and 2014 , respectively, and $54,000 and $2.0 million during the six months ended June 30, 2015 and 2014 , respectively. As each home in a capital project is completed and becomes available for lease-up, the Operating Partnership ceases capitalization on the related portion and depreciation commences over the estimated useful life. In June 2015, the General Partner and the Operating Partnership entered into a definitive agreement with an affiliate of Lone Star Funds (“Lone Star”) and Home Properties, L.P. (“Home”) to acquire up to six communities valued at $908.0 million in exchange for a combination of partnership units of a newly formed operating partnership ("UDR DownREIT Units"), cash and the assumption of debt. The agreement provides that each Home unitholder will have the option to elect to receive cash from Lone Star, UDR DownREIT Units, or a combination of cash and UDR DownREIT Units. The number of UDR DownREIT Units and the amount of cash will be determined at the closing of the consent solicitation of the Home unitholders, which we anticipate to be completed by mid-August, 2015. If all Home unitholders elect to receive UDR DownREIT Units, the transaction would be funded through the issuance of approximately $753.0 million of UDR DownREIT Units at $35 per unit, the assumption of $90.0 million of debt and $65.0 million in cash, inclusive of transfer taxes and loan assumption fees. Based upon the level of Home unitholders electing to receive UDR DownREIT Units, UDR will have the option to either acquire less than six properties or to acquire some of the properties through a Section 1031 exchange pursuant to the Internal Revenue Code. The closing of the transaction is subject to certain customary closing conditions, including, among others, the satisfaction (or waiver) of certain closing conditions to the merger between Lone Star and Home, and is anticipated to occur during the fourth quarter of 2015. The acquired properties will be owned and consolidated by UDR but only partially owned and accounted for as an equity method investment by the Operating Partnership.

Discontinued Operations

Discontinued Operations	6 Months Ended
	Jun. 30, 2015
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 six months ended June 30, 2014 , gains (net of tax) of $26.7 million and $49.9 million , respectively, from disposition of real estate, excluding a $1.1 million gain related to the sale of land, 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. As of June 30, 2014 , the Company held 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 operating results of the property for the three and six months ended June 30, 2014 are included in Income/(loss) from discontinued operations, net of tax on the Consolidated Statements of Operations. The property was subsequently sold during the third quarter of 2014. The following is a summary of income/(loss) from discontinued operations, net of tax for the three and six months ended June 30, 2015 and 2014 ( dollars in thousands ): Three Months Ended Six Months Ended June 30, June 30, 2015 2014 2015 2014 Rental income $ — $ 78 $ — $ 126 Rental expenses — 89 — 214 Property management — 2 — 3 Interest income and other (income)/expense, net — 9 — 18 Income tax benefit/(expense) — 40 — 40 Income/(loss) from discontinued operations, net of tax $ — $ 18 $ — $ (69 ) Income/(loss) from discontinued operations attributable to UDR, Inc. $ — $ 17 $ — $ (67 )

Joint Ventures

Joint Ventures	6 Months Ended
	Jun. 30, 2015
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. Unconsolidated Joint Ventures and Partnerships The Company recognizes income or losses from our investments in unconsolidated joint ventures and partnerships consisting of our proportionate share of the net income 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 June 30, 2015 and December 31, 2014 (dollars in thousands) : Joint Venture Location of Properties Number of Properties Number of Apartment Homes Investment at UDR’s Ownership Interest June 30, June 30, June 30, December 31, June 30, December 31, Operating and development: UDR/MetLife I Various 4 land parcels — $ 14,181 $ 13,306 16.1 % 15.7 % UDR/MetLife II Various 21 operating communities 4,642 428,321 431,277 50.0 % 50.0 % Other UDR/MetLife Development Joint Ventures 1 operating community; 4 development communities (a); Various 1 land parcels 1,437 158,172 134,939 50.6 % 50.6 % UDR/MetLife Vitruvian Park® Addison, TX 3 operating communities 6 land parcels 1,130 75,531 80,302 50.0 % 50.0 % UDR/KFH Washington, D.C. 3 operating communities 660 19,775 21,596 30.0 % 30.0 % Texas (b) Texas — — — (25,901 ) — % 20.0 % Investment in and advances to unconsolidated joint ventures, net, before participating loan investment 695,980,000 695,980 655,519 Income from Investment Investment at Three Months Ended June 30, Six Months Ended June 30, Location Rate Years To Maturity June 30, December 31, 2015 2014 2015 2014 Participating loan investment: Steele Creek Denver, CO 6.5% 2.1 85,208 62,707 $ 1,352 $ 456 $ 2,506 $ 777 Preferred equity investment: West Coast Development Joint Venture (c) Various 6.5% — 133,627 — $ (548 ) $ — $ (548 ) $ — Total investment in and advances to unconsolidated joint ventures, net $ 914,815 $ 718,226 (a) 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 June 30, 2015 , no apartment homes had been completed in Other UDR/MetLife Development Joint Ventures. (b) In January 2015, the eight communities held by the Texas Joint Venture were sold, generating net proceeds to UDR of $43.5 million . The Company recorded promote and disposition fee income of $9.6 million and a gain of $59.1 million (including $24.2 million of previously deferred gains) in connection with the sale. (c) In May 2015, the Company entered into a joint venture agreement with real estate private equity firm, The Wolff Company (“Wolff”), and agreed to pay $136.3 million for a 48 percent interest in a portfolio of five communities that are currently under construction (the "West Coast Development Joint Venture"). As of June 30, 2015, the Company had funded $129.6 million of its investment and had a remaining commitment of $6.7 million . The communities are located in three of the Company’s core, coastal markets: Metro Seattle, Los Angeles and Orange County, CA. UDR earns a 6.5 percent preferred return on its investment through each individual community’s date of stabilization, defined as when a community reaches 80 percent occupancy for ninety consecutive days, while Wolff is allocated all operating income and expense during the pre-stabilization period. Upon stabilization, income and expense will be shared based on each partner’s ownership percentage. The Company will serve as property manager and be paid a management fee during the lease-up phase and subsequent operation of each of the communities. Wolff is the general partner of the joint venture and the developer of the communities. The Company has a fixed price option to acquire Wolff’s remaining interest in each community beginning one year after completion. If the options are exercised for all five communities, the Company’s total price will be $597.4 million . In the event the Company does not exercise its options to purchase at least two communities, Wolff will be entitled to earn a contingent disposition fee equal to 6.5 percent return on its implied equity in the communities not acquired. Wolff is providing certain guaranties and there will be construction loans on all five communities. Once completed, the five communities will contain 1,533 homes. The Company has concluded it does not control the joint venture and accounts for it under the equity method of accounting. The Company's recorded equity investment in the West Coast Development Joint Venture at June 30, 2015 of $133.6 million is inclusive of outside basis costs and our accrued but unpaid preferred return. During the three and six months ended June 30, 2015 , the Company earned a preferred return of $1.0 million , offset by its share of the West Coast Development Joint Venture transaction expenses of $1.5 million . As of June 30, 2015 and December 31, 2014 , the Company had deferred fees and deferred profit from the sale of properties to joint ventures or partnerships of $6.8 million and $28.5 million , respectively, which will be recognized through income 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 $2.6 million and $2.3 million for the three months ended June 30, 2015 and 2014 , respectively, and $5.2 million and $5.6 million for the six months ended June 30, 2015 and 2014 , 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 six months ended June 30, 2015 and 2014 . Combined summary balance sheets relating to all of the unconsolidated joint ventures and partnerships (not just our proportionate share) are presented below as of June 30, 2015 and December 31, 2014 ( dollars in thousands ): June 30, December 31, 2014 Total real estate, net $ 3,004,723 $ 2,941,803 Assets held for sale — 216,196 Cash and cash equivalents 36,820 32,544 Other assets 32,869 28,707 Total assets $ 3,074,412 $ 3,219,250 Amount due to UDR $ 6,434 $ 2,997 Third party debt 1,529,724 1,504,477 Liabilities held for sale — 229,706 Accounts payable and accrued liabilities 63,521 44,335 Total liabilities 1,599,679 1,781,515 Total equity 1,474,733 1,437,735 Total liabilities and equity $ 3,074,412 $ 3,219,250 UDR’s investment in unconsolidated joint ventures $ 914,815 $ 718,226 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 six months ended June 30, 2015 and 2014 ( dollars in thousands ) : Three Months Ended Six Months Ended June 30, June 30, 2015 2014 2015 2014 Total revenues $ 55,450 $ 48,379 $ 109,996 $ 87,334 Property operating expenses (21,557 ) (18,001 ) (41,724 ) (32,360 ) Real estate depreciation and amortization (19,402 ) (16,808 ) (38,754 ) (31,496 ) Operating income/(loss) 14,491 13,570 29,518 23,478 Interest expense (16,169 ) (14,928 ) (32,230 ) (27,079 ) Other income/(expense) (7 ) — (7 ) — Income/(loss) from discontinued operations — (4,705 ) 182,488 (31,688 ) Net income/(loss) $ (1,685 ) $ (6,063 ) $ 179,769 $ (35,289 ) UDR income/(loss) from unconsolidated entities $ (573 ) $ (428 ) $ 58,586 $ (3,993 )

Secured and Unsecured Debt

Secured and Unsecured Debt	6 Months Ended
	Jun. 30, 2015
Debt Disclosure [Abstract]
Debt Disclosure [Text Block]	SECURED AND UNSECURED DEBT The following is a summary of our secured and unsecured debt at June 30, 2015 and December 31, 2014 ( dollars in thousands ): Six Months Ended Principal Outstanding June 30, 2015 June 30, December 31, 2014 Weighted Average Interest Rate Weighted Average Years to Maturity Number of Communities Encumbered Secured Debt: Fixed Rate Debt Mortgage notes payable (a) $ 408,736 $ 401,210 5.50 % 1.1 7 Fannie Mae credit facilities (b) 566,288 568,086 5.12 % 3.5 21 Total fixed rate secured debt 975,024 969,296 5.28 % 2.5 28 Variable Rate Debt Mortgage notes payable 31,337 31,337 1.94 % 1.6 1 Tax-exempt secured notes payable (c) 94,700 94,700 0.84 % 7.7 2 Fannie Mae credit facilities (b) 249,378 266,196 1.63 % 4.8 7 Total variable rate secured debt 375,415 392,233 1.45 % 5.3 10 Total Secured Debt 1,350,439 1,361,529 4.22 % 3.3 38 Unsecured Debt: Commercial Banks Borrowings outstanding under an unsecured credit facility due December 2017 (d) (f) 457,000 152,500 1.12 % 2.4 Senior Unsecured Notes 5.25% Medium-Term Notes due January 2015 (net of discounts of $0 and $6, respectively) (e) — 325,169 — % — 5.25% Medium-Term Notes due January 2016 83,260 83,260 5.25 % 0.5 6.21% Term Notes due July 2016 12,609 — 6.21 % 1.0 4.25% Medium-Term Notes due June 2018 (net of discounts of $1,251 and $1,465, respectively) (f) 298,749 298,535 4.25 % 2.9 1.70% Term Notes due June 2018 (f) 215,000 215,000 1.70 % 2.9 1.53% Term Notes due June 2018 (f) 100,000 100,000 1.53 % 2.9 1.33% Term Notes due June 2018 (f) 35,000 35,000 1.33 % 2.9 3.70% Medium-Term Notes due October 2020 (net of discounts of $42 and $46, respectively) (f) 299,958 299,954 3.70 % 5.3 4.63% Medium-Term Notes due January 2022 (net of discounts of $2,344 and $2,523, respectively) (f) 397,656 397,477 4.63 % 6.5 3.75% Medium-Term Notes due July 2024 (net of discount of $938 and $990, respectively) (f) 299,062 299,010 3.75 % 9.0 8.50% Debentures due September 2024 15,644 15,644 8.50 % 9.2 Other 26 27 N/A N/A Total Unsecured Debt 2,213,964 2,221,576 3.20 % 4.6 Total Debt $ 3,564,403 $ 3,583,105 3.58 % 4.1 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. As of June 30, 2015 , secured debt encumbered $2.2 billion or 26.6% of UDR’s total real estate owned based upon gross book value ( $6.2 billion or 73.4% of UDR’s real estate owned based on gross book value is unencumbered). (a) At June 30, 2015 , 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 6.16% . The Company will from time to time acquire properties subject to fixed rate debt instruments. In those situations, the Company records the 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 $1.2 million during the three months ended June 30, 2015 and 2014 , respectively, and $2.4 million and $2.5 million during the six months ended June 30, 2015 and 2014 , respectively. The unamortized fair market adjustment was a net premium of $5.7 million and $6.7 million at June 30, 2015 and December 31, 2014 , respectively. (b) UDR has three secured credit facilities with Fannie Mae with an aggregate commitment of $815.7 million at June 30, 2015 . The Fannie Mae credit facilities mature at various dates from May 2017 through July 2023 and bear interest at floating and fixed rates. At June 30, 2015 , $566.3 million of the outstanding balance was fixed and had a weighted average interest rate of 5.12% and the remaining balance of $249.4 million had a weighted average variable interest rate of 1.63% . Further information related to these credit facilities is as follows (dollars in thousands) : June 30, December 31, 2014 Borrowings outstanding $ 815,666 $ 834,282 Weighted average borrowings during the period ended 830,434 835,873 Maximum daily borrowings during the period ended 834,003 837,564 Weighted average interest rate during the period ended 4.0 % 4.1 % Weighted average interest rate at the end of the period 4.1 % 4.0 % (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 0.84% and 0.85% as of June 30, 2015 . (d) As of June 30, 2015 , 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 revolving credit facility at June 30, 2015 and December 31, 2014 (dollars in thousands): June 30, December 31, 2014 Total revolving credit facility $ 900,000 $ 900,000 Borrowings outstanding at end of period (1) 457,000 152,500 Weighted average daily borrowings during the period ended 402,514 291,761 Maximum daily borrowings during the period ended 539,100 625,000 Weighted average interest rate during the period ended 1.2 % 1.2 % Interest rate at end of the period 1.1 % 1.1 % (1) Excludes $2.3 million and $1.9 million of letters of credit at June 30, 2015 and December 31, 2014 , respectively. (e) Paid off at maturity with borrowings under the Company's $900 million unsecured revolving credit facility. (f) The Operating Partnership is a guarantor of this debt. The aggregate maturities, including amortizing principal payments of unsecured and secured debt, of total debt for the next five calendar years subsequent to June 30, 2015 are as follows (dollars in thousands): Year Total Fixed Secured Debt Total Variable Secured Debt Total Secured Debt Total Unsecured Debt (a) Total Debt 2015 $ 191,363 $ — $ 191,363 $ 79 $ 191,442 2016 148,223 — 148,223 94,469 242,692 2017 177,882 96,337 274,219 457,000 731,219 2018 121,685 87,969 209,654 648,445 858,099 2019 245,871 67,700 313,571 — 313,571 Thereafter 90,000 123,409 213,409 1,013,971 1,227,380 Total $ 975,024 $ 375,415 $ 1,350,439 $ 2,213,964 $ 3,564,403 (a) With the exception of the 1.33% 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 June 30, 2015 .

Debt (UNITED DOMINION REALTY, L

Debt (UNITED DOMINION REALTY, L.P.)	6 Months Ended
	Jun. 30, 2015
Entity Information [Line Items]
DEBT	SECURED AND UNSECURED DEBT The following is a summary of our secured and unsecured debt at June 30, 2015 and December 31, 2014 ( dollars in thousands ): Six Months Ended Principal Outstanding June 30, 2015 June 30, December 31, 2014 Weighted Average Interest Rate Weighted Average Years to Maturity Number of Communities Encumbered Secured Debt: Fixed Rate Debt Mortgage notes payable (a) $ 408,736 $ 401,210 5.50 % 1.1 7 Fannie Mae credit facilities (b) 566,288 568,086 5.12 % 3.5 21 Total fixed rate secured debt 975,024 969,296 5.28 % 2.5 28 Variable Rate Debt Mortgage notes payable 31,337 31,337 1.94 % 1.6 1 Tax-exempt secured notes payable (c) 94,700 94,700 0.84 % 7.7 2 Fannie Mae credit facilities (b) 249,378 266,196 1.63 % 4.8 7 Total variable rate secured debt 375,415 392,233 1.45 % 5.3 10 Total Secured Debt 1,350,439 1,361,529 4.22 % 3.3 38 Unsecured Debt: Commercial Banks Borrowings outstanding under an unsecured credit facility due December 2017 (d) (f) 457,000 152,500 1.12 % 2.4 Senior Unsecured Notes 5.25% Medium-Term Notes due January 2015 (net of discounts of $0 and $6, respectively) (e) — 325,169 — % — 5.25% Medium-Term Notes due January 2016 83,260 83,260 5.25 % 0.5 6.21% Term Notes due July 2016 12,609 — 6.21 % 1.0 4.25% Medium-Term Notes due June 2018 (net of discounts of $1,251 and $1,465, respectively) (f) 298,749 298,535 4.25 % 2.9 1.70% Term Notes due June 2018 (f) 215,000 215,000 1.70 % 2.9 1.53% Term Notes due June 2018 (f) 100,000 100,000 1.53 % 2.9 1.33% Term Notes due June 2018 (f) 35,000 35,000 1.33 % 2.9 3.70% Medium-Term Notes due October 2020 (net of discounts of $42 and $46, respectively) (f) 299,958 299,954 3.70 % 5.3 4.63% Medium-Term Notes due January 2022 (net of discounts of $2,344 and $2,523, respectively) (f) 397,656 397,477 4.63 % 6.5 3.75% Medium-Term Notes due July 2024 (net of discount of $938 and $990, respectively) (f) 299,062 299,010 3.75 % 9.0 8.50% Debentures due September 2024 15,644 15,644 8.50 % 9.2 Other 26 27 N/A N/A Total Unsecured Debt 2,213,964 2,221,576 3.20 % 4.6 Total Debt $ 3,564,403 $ 3,583,105 3.58 % 4.1 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. As of June 30, 2015 , secured debt encumbered $2.2 billion or 26.6% of UDR’s total real estate owned based upon gross book value ( $6.2 billion or 73.4% of UDR’s real estate owned based on gross book value is unencumbered). (a) At June 30, 2015 , 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 6.16% . The Company will from time to time acquire properties subject to fixed rate debt instruments. In those situations, the Company records the 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 $1.2 million during the three months ended June 30, 2015 and 2014 , respectively, and $2.4 million and $2.5 million during the six months ended June 30, 2015 and 2014 , respectively. The unamortized fair market adjustment was a net premium of $5.7 million and $6.7 million at June 30, 2015 and December 31, 2014 , respectively. (b) UDR has three secured credit facilities with Fannie Mae with an aggregate commitment of $815.7 million at June 30, 2015 . The Fannie Mae credit facilities mature at various dates from May 2017 through July 2023 and bear interest at floating and fixed rates. At June 30, 2015 , $566.3 million of the outstanding balance was fixed and had a weighted average interest rate of 5.12% and the remaining balance of $249.4 million had a weighted average variable interest rate of 1.63% . Further information related to these credit facilities is as follows (dollars in thousands) : June 30, December 31, 2014 Borrowings outstanding $ 815,666 $ 834,282 Weighted average borrowings during the period ended 830,434 835,873 Maximum daily borrowings during the period ended 834,003 837,564 Weighted average interest rate during the period ended 4.0 % 4.1 % Weighted average interest rate at the end of the period 4.1 % 4.0 % (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 0.84% and 0.85% as of June 30, 2015 . (d) As of June 30, 2015 , 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 revolving credit facility at June 30, 2015 and December 31, 2014 (dollars in thousands): June 30, December 31, 2014 Total revolving credit facility $ 900,000 $ 900,000 Borrowings outstanding at end of period (1) 457,000 152,500 Weighted average daily borrowings during the period ended 402,514 291,761 Maximum daily borrowings during the period ended 539,100 625,000 Weighted average interest rate during the period ended 1.2 % 1.2 % Interest rate at end of the period 1.1 % 1.1 % (1) Excludes $2.3 million and $1.9 million of letters of credit at June 30, 2015 and December 31, 2014 , respectively. (e) Paid off at maturity with borrowings under the Company's $900 million unsecured revolving credit facility. (f) The Operating Partnership is a guarantor of this debt. The aggregate maturities, including amortizing principal payments of unsecured and secured debt, of total debt for the next five calendar years subsequent to June 30, 2015 are as follows (dollars in thousands): Year Total Fixed Secured Debt Total Variable Secured Debt Total Secured Debt Total Unsecured Debt (a) Total Debt 2015 $ 191,363 $ — $ 191,363 $ 79 $ 191,442 2016 148,223 — 148,223 94,469 242,692 2017 177,882 96,337 274,219 457,000 731,219 2018 121,685 87,969 209,654 648,445 858,099 2019 245,871 67,700 313,571 — 313,571 Thereafter 90,000 123,409 213,409 1,013,971 1,227,380 Total $ 975,024 $ 375,415 $ 1,350,439 $ 2,213,964 $ 3,564,403 (a) With the exception of the 1.33% 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 June 30, 2015 .
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 June 30, 2015 and December 31, 2014 ( dollars in thousands ): Six Months Ended Principal Outstanding June 30, 2015 June 30, December 31, 2014 Weighted Average Interest Rate Weighted Average Years to Maturity Number of Communities Encumbered Fixed Rate Debt Mortgage notes payable $ 374,056 $ 378,371 5.49 % 1.1 5 Fannie Mae credit facilities 334,002 333,828 4.90 % 4.1 9 Total fixed rate secured debt 708,058 712,199 5.21 % 2.5 14 Variable Rate Debt Tax-exempt secured note payable 27,000 27,000 0.85 % 16.7 1 Fannie Mae credit facilities 177,509 192,760 1.88 % 5.7 5 Total variable rate secured debt 204,509 219,760 1.74 % 7.1 6 Total Secured Debt $ 912,567 $ 931,959 4.43 % 3.5 20 As of June 30, 2015 , an aggregate commitment of $511.5 million of the General Partner's secured credit facilities with Fannie Mae was allocated to the Operating Partnership based on the ownership of the assets securing the debt. The entire commitment was outstanding at June 30, 2015 . The Fannie Mae credit facilities mature at various dates from May 2017 through July 2023 and bear interest at floating and fixed rates. At June 30, 2015 , $334.0 million of the outstanding balance was fixed and had a weighted average interest rate of 4.90% and the remaining balance of $177.5 million on these facilities had a weighted average variable interest rate of 1.88% . The following information relates to the credit facilities allocated to the Operating Partnership (dollars in thousands) : June 30, December 31, 2014 Borrowings outstanding $ 511,511 $ 526,588 Weighted average borrowings during the period ended 520,773 527,592 Maximum daily borrowings during the period 523,011 528,659 Weighted average interest rate during the period ended 3.8 % 4.1 % Interest rate at the end of the period 3.9 % 4.0 % 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 $4.2 million and $6.2 million at June 30, 2015 and December 31, 2014 , 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 June 30, 2015 , the General Partner had borrowings against its fixed rate facilities of $566.3 million , of which $334.0 million was allocated to the Operating Partnership based on the ownership of the assets securing the debt. As of June 30, 2015 , the fixed rate Fannie Mae credit facilities allocated to the Operating Partnership had a weighted average fixed interest rate of 4.90% . 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 0.85% as of June 30, 2015 . Secured credit facilities. At June 30, 2015 , the General Partner had borrowings against its variable rate facilities of $249.4 million , of which $177.5 million was allocated to the Operating Partnership based on the ownership of the assets securing the debt. As of June 30, 2015 , 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 June 30, 2015 are as follows (dollars in thousands): Fixed Variable Year Mortgage Notes Payable Secured Credit Facilities Tax-Exempt Secured Notes Payable Secured Credit Facilities Total 2015 $ 188,759 $ 184 $ — $ — $ 188,943 2016 131,946 385 — — 132,331 2017 1,630 15,640 — 6,566 23,836 2018 1,685 111,256 — 81,559 194,500 2019 50,036 123,095 — — 173,131 Thereafter — 83,442 27,000 89,384 199,826 Total $ 374,056 $ 334,002 $ 27,000 $ 177,509 $ 912,567 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 June 30, 2015 and December 31, 2014 , the outstanding balance under the unsecured revolving credit facility was $457.0 million and $152.5 million , respectively.

Income_(Loss) Per Share

Income/(Loss) Per Share	6 Months Ended
	Jun. 30, 2015
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 Six Months Ended June 30, June 30, 2015 2014 2015 2014 Numerator for income/(loss) per share: Income/(loss) from continuing operations $ 10,842 $ 4,359 $ 87,259 $ (836 ) Gain/(loss) on sale of real estate owned, net of tax 79,042 26,709 79,042 51,003 (Income)/loss from continuing operations attributable to redeemable noncontrolling interests in the Operating Partnership (3,029 ) (1,076 ) (5,617 ) (1,726 ) (Income)/loss from continuing operations attributable to noncontrolling interests — (2 ) (7 ) (6 ) Income/(loss) from continuing operations attributable to UDR, Inc. 86,855 29,990 160,677 48,435 Distributions to preferred stockholders - Series E (Convertible) (931 ) (931 ) (1,862 ) (1,862 ) Income/(loss) from continuing operations attributable to common stockholders - basic $ 85,924 $ 29,059 $ 158,815 $ 46,573 Dilutive distributions to preferred stockholders - Series E (Convertible) 931 — — — Income/(loss) from continuing operations attributable to common stockholders - diluted $ 86,855 $ 29,059 $ 158,815 $ 46,573 Income/(loss) from discontinued operations, net of tax $ — $ 18 $ — $ (69 ) (Income)/loss from discontinued operations attributable to redeemable noncontrolling interests in the Operating Partnership — (1 ) — 2 Income/(loss) from discontinued operations attributable to common stockholders $ — $ 17 $ — $ (67 ) Net income/(loss) attributable to common stockholders 85,924 29,076 $ 158,815 $ 46,506 Denominator for income/(loss) per share: Weighted average common shares outstanding 259,028 251,458 258,567 251,336 Non-vested restricted stock awards (1,179 ) (1,203 ) (1,223 ) (1,120 ) Denominator for basic income/(loss) per share 257,849 250,255 257,344 250,216 Incremental shares issuable from assumed conversion of preferred stock, stock options, and unvested restricted stock 4,957 1,936 1,923 1,875 Denominator for diluted income/(loss) per share 262,806 252,191 259,267 252,091 Income/(loss) per weighted average common share-basic: Income/(loss) from continuing operations attributable to common stockholders $ 0.33 $ 0.12 $ 0.62 $ 0.19 Income/(loss) from discontinued operations attributable to common stockholders — — — — Net income/(loss) attributable to common stockholders $ 0.33 $ 0.12 $ 0.62 $ 0.19 Income/(loss) per weighted average common share-diluted: Income/(loss) from continuing operations attributable to common stockholders $ 0.33 $ 0.12 $ 0.61 $ 0.18 Income/(loss) from discontinued operations attributable to common stockholders — — — — Net income/(loss) attributable to common stockholders $ 0.33 $ 0.12 $ 0.61 $ 0.18 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. For the three months ended June 30, 2015 , the Company's Series E preferred stock was dilutive for purposes of calculating earnings per share. For the six months ended June 30, 2015 , and the three and six months ended June 30, 2014 , the Company's Series E preferred stock was anti-dilutive. 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 six months ended June 30, 2015 and 2014 (shares in thousands) : Three Months Ended Six Months Ended June 30, June 30, 2015 2014 2015 2014 OP Units 9,125 9,316 9,145 9,317 Preferred stock 3,036 3,036 3,036 3,036 Stock options and unvested restricted stock 1,921 1,936 1,923 1,875

Noncontrolling Interests

Noncontrolling Interests	6 Months Ended
	Jun. 30, 2015
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, 2014 $ 282,480 Mark-to-market adjustment to redeemable noncontrolling interests in the Operating Partnership 10,930 Conversion of OP Units to Common Stock (3,498 ) Net income/(loss) attributable to redeemable noncontrolling interests in the Operating Partnership 5,617 Distributions to redeemable noncontrolling interests in the Operating Partnership (5,250 ) Allocation of other comprehensive income/(loss) (1 ) Redeemable noncontrolling interests in the Operating Partnership, June 30, 2015 $ 290,278 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 Six Months Ended June 30, June 30, 2015 2014 2015 2014 Net income/(loss) attributable to common stockholders $ 85,924 $ 29,076 $ 158,815 $ 46,506 Conversion of OP Units to UDR Common stock 3,479 191 3,498 191 Change in equity from net income/(loss) attributable to common stockholders and conversion of OP Units to UDR Common Stock $ 89,403 $ 29,267 $ 162,313 $ 46,697 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 $0 and $(2,000) during the three months ended June 30, 2015 and 2014 , respectively, and $(7,000) and $(6,000) during the six months ended June 30, 2015 and 2014 , respectively

Related Party Transactions (UNI

Related Party Transactions (UNITED DOMINION REALTY, L.P.)	6 Months Ended
	Jun. 30, 2015
United Dominion Reality L.P. [Member]
Entity Information [Line Items]
RELATED PARTY TRANSACTIONS	RELATED PARTY TRANSACTIONS Advances (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 Advances (to)/from General Partner of $3.0 million and $13.6 million at June 30, 2015 and December 31, 2014 , respectively, which are reflected as increases of capital 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 $5.7 million and $7.2 million during the three months ended June 30, 2015 and 2014 , respectively, and $9.9 million and $13.9 million during the six months ended June 30, 2015 and 2014 , 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 months ended June 30, 2015 and 2014 , the Operating Partnership incurred $4.3 million and $3.1 million , respectively, and during the six months ended June 30, 2015 and 2014 incurred $8.6 million and $6.2 million , respectively, of related party management fees related to a management agreement entered into in 2011 with wholly-owned subsidiaries of UDR's taxable REIT subsidiaries ("TRS"). (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 UDR's TRS 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 UDR's TRSs. 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 June 30, 2015 and December 31, 2014 , 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 $1.2 million during the three months ended June 30, 2015 and 2014 , respectively and $2.3 million and $2.3 million during the six months ended June 30, 2015 and 2014 , respectively.

Fair Value of Derivatives and F

Fair Value of Derivatives and Financial Instruments	6 Months Ended
	Jun. 30, 2015
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 June 30, 2015 and December 31, 2014 are summarized as follows (dollars in thousands) : Fair Value at June 30, 2015, Using Total Carrying Amount in Statement of Financial Position at June 30, 2015 Fair Value Estimate at June 30, 2015 Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Description: Notes receivable (a) $ 15,494 $ 15,863 $ — $ — $ 15,863 Derivatives - Interest rate contracts (b) 12 12 — 12 — Total assets $ 15,506 $ 15,875 $ — $ 12 $ 15,863 Derivatives - Interest rate contracts (b) $ 9,109 $ 9,109 $ — $ 9,109 $ — Secured debt instruments - fixed rate: (c) Mortgage notes payable 408,736 420,571 — — 420,571 Fannie Mae credit facilities 566,288 592,916 — — 592,916 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 249,378 249,378 — — 249,378 Unsecured debt instruments: (c) Commercial bank 457,000 457,000 — — 457,000 Senior unsecured notes 1,756,964 1,816,636 — — 1,816,636 Total liabilities $ 3,573,512 $ 3,671,647 $ — $ 9,109 $ 3,662,538 Redeemable noncontrolling interests in the Operating Partnership (d) $ 290,278 $ 290,278 $ — $ 290,278 $ — Fair Value at December 31, 2014, Using Total Carrying Amount in Statement of Financial Position at December 31, 2014 Fair Value Estimate at December 31, 2014 Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Description: Notes receivable (a) $ 14,369 $ 14,808 $ — $ — $ 14,808 Derivatives - Interest rate contracts (b) 88 88 — 88 — Total assets $ 14,457 $ 14,896 $ — $ 88 $ 14,808 Derivatives- Interest rate contracts (b) $ 10,368 $ 10,368 $ — $ 10,368 $ — Secured debt instruments - fixed rate: (c) Mortgage notes payable 401,210 415,663 — — 415,663 Fannie Mae credit facilities 568,086 606,623 — — 606,623 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 266,196 266,196 — — 266,196 Unsecured debt instruments: (c) Commercial bank 152,500 152,500 — — 152,500 Senior unsecured notes 2,069,076 2,144,125 — — 2,144,125 Total liabilities $ 3,593,473 $ 3,721,512 $ — $ 10,368 $ 3,711,144 Redeemable noncontrolling interests in the Operating Partnership (d) $ 282,480 $ 282,480 $ — $ 282,480 $ — (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. 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 June 30, 2015 and December 31, 2014 , 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 June 30, 2015 , 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 six months ended June 30, 2015 and 2014 . 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 and29

Fair Value of Derivatives and Financial Instruments (UNITED DOMINION REALTY, L.P.)	6 Months Ended
	Jun. 30, 2015
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 June 30, 2015 and December 31, 2014 are summarized as follows (dollars in thousands) : Fair Value at June 30, 2015, Using Total Carrying Amount in Statement of Financial Position at June 30, 2015 Fair Value Estimate at June 30, 2015 Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Description: Notes receivable (a) $ 15,494 $ 15,863 $ — $ — $ 15,863 Derivatives - Interest rate contracts (b) 12 12 — 12 — Total assets $ 15,506 $ 15,875 $ — $ 12 $ 15,863 Derivatives - Interest rate contracts (b) $ 9,109 $ 9,109 $ — $ 9,109 $ — Secured debt instruments - fixed rate: (c) Mortgage notes payable 408,736 420,571 — — 420,571 Fannie Mae credit facilities 566,288 592,916 — — 592,916 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 249,378 249,378 — — 249,378 Unsecured debt instruments: (c) Commercial bank 457,000 457,000 — — 457,000 Senior unsecured notes 1,756,964 1,816,636 — — 1,816,636 Total liabilities $ 3,573,512 $ 3,671,647 $ — $ 9,109 $ 3,662,538 Redeemable noncontrolling interests in the Operating Partnership (d) $ 290,278 $ 290,278 $ — $ 290,278 $ — Fair Value at December 31, 2014, Using Total Carrying Amount in Statement of Financial Position at December 31, 2014 Fair Value Estimate at December 31, 2014 Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Description: Notes receivable (a) $ 14,369 $ 14,808 $ — $ — $ 14,808 Derivatives - Interest rate contracts (b) 88 88 — 88 — Total assets $ 14,457 $ 14,896 $ — $ 88 $ 14,808 Derivatives- Interest rate contracts (b) $ 10,368 $ 10,368 $ — $ 10,368 $ — Secured debt instruments - fixed rate: (c) Mortgage notes payable 401,210 415,663 — — 415,663 Fannie Mae credit facilities 568,086 606,623 — — 606,623 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 266,196 266,196 — — 266,196 Unsecured debt instruments: (c) Commercial bank 152,500 152,500 — — 152,500 Senior unsecured notes 2,069,076 2,144,125 — — 2,144,125 Total liabilities $ 3,593,473 $ 3,721,512 $ — $ 10,368 $ 3,711,144 Redeemable noncontrolling interests in the Operating Partnership (d) $ 282,480 $ 282,480 $ — $ 282,480 $ — (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. 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 June 30, 2015 and December 31, 2014 , 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 June 30, 2015 , 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 six months ended June 30, 2015 and 2014 . 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 June 30, 2015 and December 31, 2014 are summarized as follows (dollars in thousands) : Fair Value at June 30, 2015, Using Total Carrying Amount in Statement of Financial Position at June 30, 2015 Fair Value Estimate at June 30, 2015 Quoted Prices in Significant Significant Description: Derivatives - Interest rate contracts (a) $ 7 $ 7 $ — $ 7 $ — Total assets $ 7 $ 7 $ — $ 7 $ — Derivatives - Interest rate contracts (a) $ 436 $ 436 $ — $ 436 $ — Secured debt instruments - fixed rate: (b) Mortgage notes payable 374,056 384,909 — — 384,909 Fannie Mae credit facilities 334,002 349,634 — — 349,634 Secured debt instruments - variable rate: (b) Tax-exempt secured notes payable 27,000 27,000 — — 27,000 Fannie Mae credit facilities 177,509 177,509 — — 177,509 Total liabilities $ 913,003 $ 939,488 $ — $ 436 $ 939,052 Fair Value at December 31, 2014, Using Total Carrying Amount in Statement of Financial Position at December 31, 2014 Fair Value Estimate at December 31, 2014 Quoted Prices in Significant Significant Description: Derivatives - Interest rate contracts (a) $ 39 $ 39 $ — $ 39 $ — Total assets $ 39 $ 39 $ — $ 39 $ — Derivatives - Interest rate contracts (a) $ 918 $ 918 $ — $ 918 $ — Secured debt instruments - fixed rate: (b) Mortgage notes payable 378,371 391,835 — — 391,835 Fannie Mae credit facilities 333,828 355,470 — — 355,470 Secured debt instruments - variable rate: (b) Tax-exempt secured notes payable 27,000 27,000 — — 27,000 Fannie Mae credit facilities 192,760 192,760 — — 192,760 Total liabilities $ 932,877 $ 967,983 $ — $ 918 $ 967,065 (a) See Note 7, Derivatives and Hedging Activity. (b) See Note 4, 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 June 30, 2015 and December 31, 2014 , 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 June 30, 2015 , 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 Activit

Derivatives and Hedging Activity	6 Months Ended
	Jun. 30, 2015
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 six months ended June 30, 2015 and 2014 , 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 six months ended June 30, 2015 , the Company recorded no ineffectiveness to earnings. During the three and six months ended June 30, 2014 , the Company recorded a gain of approximately $3,000 related to the ineffective portion of the derivative, which was caused by a timing difference between the derivative and the hedge item. Amounts reported in Accumulated other comprehensive income/(loss), net in the Consolidated Balance Sheets related to derivatives that will be reclassified to interest expense as interest payments are made on the Company’s variable-rate debt. Through June 30, 2016 , the Company estimates that an additional $2.6 million will be reclassified as an increase to interest expense. As of June 30, 2015 , 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 9 $ 565,000 Interest rate caps 2 $ 219,984 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 six months ended June 30, 2015 and 2014 . As of June 30, 2015 , the Company had the following outstanding derivatives that were not designated as hedges in qualifying hedging relationships ( dollars in thousands ): Product Number of Instruments Notional Interest rate caps 2 $ 116,289 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 June 30, 2015 and December 31, 2014 ( dollars in thousands ): Asset Derivatives (included in Other assets ) Liability Derivatives (included in Other liabilities ) Fair Value at: Fair Value at: June 30, December 31, June 30, December 31, Derivatives designated as hedging instruments: Interest rate products $ 9 86 $ 9,109 $ 10,368 Derivatives not designated as hedging instruments: Interest rate products $ 3 $ 2 $ — $ — 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 six months ended June 30, 2015 and 2014 ( dollars in thousands ): Derivatives in Cash Flow Hedging Relationships Unrealized holding gain/(loss) Recognized in OCI (Effective Portion) Gain/(Loss) Reclassified from Accumulated OCI into Interest expense (Effective Portion) Gain/(Loss) Recognized in Interest expense (Ineffective Portion and Amount Excluded from Effectiveness Testing) 2015 2014 2015 2014 2015 2014 Three Months Ended June 30, Interest rate products $ 6,186 $ 304 $ (292 ) $ (1,145 ) $ — $ 3 Six Months Ended June 30, Interest rate products $ (1,366 ) $ 249 $ (1,029 ) $ (2,677 ) $ — $ 3 Gain/(Loss) Recognized in Interest income and other income/(expense), net Derivatives Not Designated as Hedging Instruments 2015 2014 Three Months Ended June 30, Interest rate products $ (22 ) $ — Six Months Ended June 30, Interest rate products $ (24 ) $ — 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 June 30, 2015 , 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 $10.7 million . As of June 30, 2015 , the Company has not posted any collateral related to these agreements. If the Company had breached any of these provisions at June 30, 2015 , it may have been required to settle its obligations under the agreements at their termination value of $10.7 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 June 30, 2015 and December 31, 2014 (dollars in thousands): Offsetting of Derivative Assets Gross Amounts of Recognized Assets Gross Amounts Offset in the Consolidated Balance Sheets Net Amounts of Assets Presented in the Consolidated Balance Sheets (a) Gross Amounts Not Offset in the Consolidated Balance Sheets Financial Instruments Cash Collateral Received Net Amount June 30, 2015 $ 12 $ — $ 12 $ — $ — $ 12 December 31, 2014 $ 88 $ — $ 88 $ (27 ) $ — $ 61 (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 of Recognized Liabilities Gross Amounts Offset in the Consolidated Balance Sheets Net Amounts of Liabilities Presented in the Consolidated Balance Sheets (b) Gross Amounts Not Offset in the Consolidated Balance Sheets Financial Instruments Cash Collateral Posted Net Amount June 30, 2015 $ 9,109 $ — $ 9,109 $ — $ — $ 9,109 December 31, 2014 $ 10,368 $ — $ 10,368 $ (27 ) $ — $ 10,341 (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 Activ31

Derivatives and Hedging Activity (UNITED DOMINION REALTY, L.P.)	6 Months Ended
	Jun. 30, 2015
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 six months ended June 30, 2015 and 2014 , 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 six months ended June 30, 2015 , the Company recorded no ineffectiveness to earnings. During the three and six months ended June 30, 2014 , the Company recorded a gain of approximately $3,000 related to the ineffective portion of the derivative, which was caused by a timing difference between the derivative and the hedge item. Amounts reported in Accumulated other comprehensive income/(loss), net in the Consolidated Balance Sheets related to derivatives that will be reclassified to interest expense as interest payments are made on the Company’s variable-rate debt. Through June 30, 2016 , the Company estimates that an additional $2.6 million will be reclassified as an increase to interest expense. As of June 30, 2015 , 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 9 $ 565,000 Interest rate caps 2 $ 219,984 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 six months ended June 30, 2015 and 2014 . As of June 30, 2015 , the Company had the following outstanding derivatives that were not designated as hedges in qualifying hedging relationships ( dollars in thousands ): Product Number of Instruments Notional Interest rate caps 2 $ 116,289 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 June 30, 2015 and December 31, 2014 ( dollars in thousands ): Asset Derivatives (included in Other assets ) Liability Derivatives (included in Other liabilities ) Fair Value at: Fair Value at: June 30, December 31, June 30, December 31, Derivatives designated as hedging instruments: Interest rate products $ 9 86 $ 9,109 $ 10,368 Derivatives not designated as hedging instruments: Interest rate products $ 3 $ 2 $ — $ — 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 six months ended June 30, 2015 and 2014 ( dollars in thousands ): Derivatives in Cash Flow Hedging Relationships Unrealized holding gain/(loss) Recognized in OCI (Effective Portion) Gain/(Loss) Reclassified from Accumulated OCI into Interest expense (Effective Portion) Gain/(Loss) Recognized in Interest expense (Ineffective Portion and Amount Excluded from Effectiveness Testing) 2015 2014 2015 2014 2015 2014 Three Months Ended June 30, Interest rate products $ 6,186 $ 304 $ (292 ) $ (1,145 ) $ — $ 3 Six Months Ended June 30, Interest rate products $ (1,366 ) $ 249 $ (1,029 ) $ (2,677 ) $ — $ 3 Gain/(Loss) Recognized in Interest income and other income/(expense), net Derivatives Not Designated as Hedging Instruments 2015 2014 Three Months Ended June 30, Interest rate products $ (22 ) $ — Six Months Ended June 30, Interest rate products $ (24 ) $ — 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 June 30, 2015 , 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 $10.7 million . As of June 30, 2015 , the Company has not posted any collateral related to these agreements. If the Company had breached any of these provisions at June 30, 2015 , it may have been required to settle its obligations under the agreements at their termination value of $10.7 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 June 30, 2015 and December 31, 2014 (dollars in thousands): Offsetting of Derivative Assets Gross Amounts of Recognized Assets Gross Amounts Offset in the Consolidated Balance Sheets Net Amounts of Assets Presented in the Consolidated Balance Sheets (a) Gross Amounts Not Offset in the Consolidated Balance Sheets Financial Instruments Cash Collateral Received Net Amount June 30, 2015 $ 12 $ — $ 12 $ — $ — $ 12 December 31, 2014 $ 88 $ — $ 88 $ (27 ) $ — $ 61 (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 of Recognized Liabilities Gross Amounts Offset in the Consolidated Balance Sheets Net Amounts of Liabilities Presented in the Consolidated Balance Sheets (b) Gross Amounts Not Offset in the Consolidated Balance Sheets Financial Instruments Cash Collateral Posted Net Amount June 30, 2015 $ 9,109 $ — $ 9,109 $ — $ — $ 9,109 December 31, 2014 $ 10,368 $ — $ 10,368 $ (27 ) $ — $ 10,341 (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 4, 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 six months ended June 30, 2015 and 2014 , 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 no gain or loss from ineffectiveness during the three and six months ended June 30, 2015 , and 2014 . 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. Through June 30, 2016 , we estimate that an additional $440,000 will be reclassified as an increase to interest expense. As of June 30, 2015 , 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 1 $ 46,357 Interest rate caps 1 $ 143,508 Derivatives not designated as hedges are not speculative and are used to manage the Operating Partnership’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 six months ended June 30, 2015 and 2014 . As of June 30, 2015 , we had the following outstanding derivatives that were not designated as a hedges in a qualifying hedging relationships ( dollars in thousands ): Product Number of Instruments Notional Interest rate caps 2 $ 109,264 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 June 30, 2015 and December 31, 2014 ( dollars in thousands ): Asset Derivatives (included in Other assets ) Liability Derivatives (included in Other liabilities ) Fair Value at: Fair Value at: June 30, December 31, June 30, December 31, Derivatives designated as hedging instruments: Interest rate products $ 4 $ 37 $ 436 $ 918 Derivatives not designated as hedging instruments: Interest rate products $ 3 $ 2 $ — $ — 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 six months ended June 30, 2015 and 2014 ( dollars in thousands ): Unrealized holding gain/(loss) Recognized in OCI (Effective Portion) Gain/(Loss) Reclassified from Accumulated OCI into Interest expense (Effective Portion) Derivatives in Cash Flow Hedging Relationships 2015 2014 2015 2014 Three Months Ended June 30, Interest rate products $ (26 ) $ (140 ) $ (267 ) $ (573 ) Six Months Ended June 30, Interest rate products $ (77 ) $ (191 ) $ (553 ) $ (1,196 ) Gain/(Loss) Recognized in Interest income and other income/(expense), net Derivatives Not Designated as Hedging Instruments 2015 2014 Three Months Ended June 30, Interest rate products $ (22 ) $ — Six Months Ended June 30, Interest rate products $ (23 ) $ — 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 June 30, 2015 and December 31, 2014 , 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 June 30, 2015 , 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 $436,000 . As of June 30, 2015 , the General Partner has not posted any collateral related to these agreements. If the General Partner had breached any of these provisions at June 30, 2015 , it would have been required to settle its obligations under the agreements at their termination value of $436,000 . 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 June 30, 2015 and December 31, 2014 : Offsetting of Derivative Assets Gross Amounts of Recognized Assets Gross Amounts Offset in the Consolidated Balance Sheets Net Amounts of Assets Presented in the Consolidated Balance Sheets (a) Gross Amounts Not Offset in the Consolidated Balance Sheets Financial Instruments Cash Collateral Received Net Amount June 30, 2015 $ 7 $ — $ 7 $ — $ — $ 7 December 31, 2014 $ 39 $ — $ 39 $ — $ — $ 39 (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 of Recognized Liabilities Gross Amounts Offset in the Consolidated Balance Sheets Net Amounts of Liabilities Presented in the Consolidated Balance Sheets (b) Gross Amounts Not Offset in the Consolidated Balance Sheets Financial Instruments Cash Collateral Posted Net Amount June 30, 2015 $ 436 $ — $ 436 $ — $ — $ 436 December 31, 2014 $ 918 $ — $ 918 $ — $ — $ 918 (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	6 Months Ended
	Jun. 30, 2015
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 $5.1 million and $3.6 million during the three months ended June 30, 2015 and 2014 , respectively, and $9.6 million and $7.3 million during the six months ended June 30, 2015 and 2014 , respectively.

Capital Structure (UNITED DOMIN

Capital Structure (UNITED DOMINION REALTY, L.P.)	6 Months Ended
	Jun. 30, 2015
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 June 30, 2015 and December 31, 2014 , all of which were held by UDR. Limited Partnership Units As of June 30, 2015 and December 31, 2014 , there were 183,167,815 limited partnership units outstanding, of which 1,873,332 were Class A Limited Partnership Units. UDR owned 174,105,126 , or 95.1% of, and 174,002,342 , or 95.0% of, OP Units outstanding at June 30, 2015 and December 31, 2014 , respectively, of which 121,661 were Class A Limited Partnership Units. The remaining 9,062,689 , or 4.9% of, and 9,165,473 , or 5.0% of, OP Units outstanding, were held by non-affiliated partners at June 30, 2015 and December 31, 2014 , 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 $290.3 million and $282.5 million as of June 30, 2015 and December 31, 2014 , 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	6 Months Ended
	Jun. 30, 2015
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 June 30, 2015 ( dollars in thousands ): Number of Properties Costs Incurred as of June 30, 2015 (a) Expected Costs to Complete Average Ownership Stake Wholly-owned — under development 1 $ 92,645 (b) $ 249,355 100 % Wholly-owned — redevelopment 1 4,854 (b) 10,146 100 % Joint ventures: Unconsolidated joint ventures 4 335,539 163,791 (c) Various Participating loan investments 1 85,208 (d) 6,801 (e) 0 % Preferred equity investments 5 129,592 (f) 6,735 (g) 48 % $ 647,838 $ 436,828 (a) Represents 100% of project costs incurred as of June 30, 2015 . (b) Costs incurred to date include $114,000 and $1.3 million of accrued fixed assets for development and redevelopment, respectively. (c) Represents UDR’s proportionate share of expected remaining costs to complete. (d) Represents the participating loan balance funded as of June 30, 2015 . (e) Represents UDR’s remaining participating loan commitment for Steele Creek. (f) Represents UDR's share of capital contributed to the West Coast Development Joint Venture as of June 30, 2015 . (g) Represents UDR's remaining funding commitment on Katella Grand II. 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.)	6 Months Ended
	Jun. 30, 2015
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 June 30, 2015 ( dollars in thousands ): Number of Properties Costs Incurred as of June 30, 2015 (a) Expected Costs to Complete Average Ownership Stake Wholly-owned — under development 1 $ 92,645 (b) $ 249,355 100 % Wholly-owned — redevelopment 1 4,854 (b) 10,146 100 % Joint ventures: Unconsolidated joint ventures 4 335,539 163,791 (c) Various Participating loan investments 1 85,208 (d) 6,801 (e) 0 % Preferred equity investments 5 129,592 (f) 6,735 (g) 48 % $ 647,838 $ 436,828 (a) Represents 100% of project costs incurred as of June 30, 2015 . (b) Costs incurred to date include $114,000 and $1.3 million of accrued fixed assets for development and redevelopment, respectively. (c) Represents UDR’s proportionate share of expected remaining costs to complete. (d) Represents the participating loan balance funded as of June 30, 2015 . (e) Represents UDR’s remaining participating loan commitment for Steele Creek. (f) Represents UDR's share of capital contributed to the West Coast Development Joint Venture as of June 30, 2015 . (g) Represents UDR's remaining funding commitment on Katella Grand II. 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 June 30, 2015 ( dollars in thousands ): Number of Properties Costs Incurred to Date (a) Expected Costs to Complete (unaudited) Real estate communities — redevelopment 1 4,854 10,146 (a) Costs incurred to date include $1.3 million of accrued fixed assets for redevelopment. 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	6 Months Ended
	Jun. 30, 2015
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 April 1, 2014 for quarter-to-date comparison and January 1, 2014 for year-to-date comparison and held as of June 30, 2015 . 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 six months ended June 30, 2015 and 2014 . The following table details rental income and NOI from continuing and discontinued operations for UDR’s reportable segments for the three and six months ended June 30, 2015 and 2014 , and reconciles NOI to Net Income/(Loss) Attributable to UDR, Inc . in the Consolidated Statements of Operations (dollars in thousands) : Three Months Ended Six Months Ended June 30, (a) June 30, (b) 2015 2014 2015 2014 Reportable apartment home segment rental income Same-Store Communities West Region $ 68,646 $ 64,004 $ 135,595 $ 126,405 Mid-Atlantic Region 43,536 42,644 86,331 84,694 Southeast Region 26,540 25,063 52,505 49,774 Northeast Region 21,436 20,294 42,328 40,096 Southwest Region 14,363 13,623 28,470 27,090 Non-Mature Communities/Other 38,243 35,409 74,582 67,378 Total consolidated rental income $ 212,764 $ 201,037 $ 419,811 $ 395,437 Reportable apartment home segment NOI Same-Store Communities West Region $ 51,400 $ 46,496 $ 100,999 $ 91,287 Mid-Atlantic Region 30,302 29,863 59,590 58,699 Southeast Region 17,876 16,769 35,207 33,465 Northeast Region 16,269 15,459 31,835 30,004 Southwest Region 8,998 8,263 17,534 16,621 Non-Mature Communities/Other 25,587 23,542 48,842 42,440 Total consolidated NOI 150,432 140,392 294,007 272,516 Reconciling items: Joint venture management and other fees 3,098 2,747 15,804 6,434 Property management (5,851 ) (5,529 ) (11,545 ) (10,875 ) Other operating expenses (1,769 ) (2,171 ) (3,535 ) (4,106 ) Real estate depreciation and amortization (90,344 ) (88,876 ) (179,121 ) (177,409 ) General and administrative (13,721 ) (12,530 ) (25,873 ) (24,524 ) Casualty-related recoveries/(charges), net (843 ) — (1,839 ) (500 ) Other depreciation and amortization (1,700 ) (1,193 ) (3,323 ) (2,273 ) Income/(loss) from unconsolidated entities (573 ) (428 ) 58,586 (3,993 ) Interest expense (29,673 ) (31,691 ) (58,473 ) (64,575 ) Interest income and other income/(expense), net 382 1,426 742 2,841 Tax benefit/(expense), net 1,404 2,230 1,829 5,559 Gain/(loss) on sale of real estate owned, net of tax 79,042 26,709 79,042 51,003 Net (income)/loss attributable to redeemable noncontrolling interests in the Operating Partnership (3,029 ) (1,077 ) (5,617 ) (1,724 ) Net (income)/loss attributable to noncontrolling interests — (2 ) (7 ) (6 ) Net income/(loss) attributable to UDR, Inc. $ 86,855 $ 30,007 $ 160,677 $ 48,368 (a) Same-Store Community population consisted of 35,250 apartment homes. (b) Same-Store Community population consisted of 35,250 apartment homes. The following table details the assets of UDR’s reportable segments as of June 30, 2015 and December 31, 2014 (dollars in thousands) : June 30, December 31, Reportable apartment home segment assets: Same-Store Communities: West Region $ 2,608,586 $ 2,592,156 Mid-Atlantic Region 1,541,420 1,533,993 Southeast Region 738,595 733,068 Northeast Region 1,081,035 1,076,656 Southwest Region 443,526 440,721 Non-Mature Communities/Other 2,012,117 2,006,665 Total assets 8,425,279 8,383,259 Accumulated depreciation (2,557,949 ) (2,434,772 ) Total assets — net book value 5,867,330 5,948,487 Reconciling items: Cash and cash equivalents 2,990 15,224 Restricted cash 22,912 22,340 Deferred financing costs, net 19,930 22,686 Notes receivable, net 15,494 14,369 Investment in and advances to unconsolidated joint ventures, net 914,815 718,226 Other assets 96,259 105,202 Total consolidated assets $ 6,939,730 $ 6,846,534 Capital expenditures related to our Same-Store Communities totaled $20.6 million and $12.8 million for the three months ended June 30, 2015 and 2014 , respectively, and $33.8 million and $20.3 million for the six months ended June 30, 2015 and 2014 , respectively. Capital expenditures related to our Non-Mature Communities/Other totaled $1.2 million and $2.5 million for the three months ended June 30, 2015 and 2014 , respectively, and $3.8 million and $4.8 million for the six months ended June 30, 2015 and 2014 . Markets included in the above geographic segments are as follows: i. West Region — Orange County, San Francisco, Seattle, Los Angeles, Monterey Peninsula, Other Southern California, and Portland ii. Mid-Atlantic Region — Metropolitan D.C., Baltimore, Richmond, Norfolk, and Other Mid-Atlantic iii. Southeast Region — Tampa, Orlando, Nashville, and Other Florida iv. Northeast Region — New York and Boston v. Southwest Region — Dallas and Austin

Reportable Segments (UNITED DOM

Reportable Segments (UNITED DOMINION REALTY, L.P.)	6 Months Ended
	Jun. 30, 2015
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 April 1, 2014 for quarter-to-date comparison and January 1, 2014 for year-to-date comparison and held as of June 30, 2015 . 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 six months ended June 30, 2015 and 2014 . The following table details rental income and NOI from continuing and discontinued operations for UDR’s reportable segments for the three and six months ended June 30, 2015 and 2014 , and reconciles NOI to Net Income/(Loss) Attributable to UDR, Inc . in the Consolidated Statements of Operations (dollars in thousands) : Three Months Ended Six Months Ended June 30, (a) June 30, (b) 2015 2014 2015 2014 Reportable apartment home segment rental income Same-Store Communities West Region $ 68,646 $ 64,004 $ 135,595 $ 126,405 Mid-Atlantic Region 43,536 42,644 86,331 84,694 Southeast Region 26,540 25,063 52,505 49,774 Northeast Region 21,436 20,294 42,328 40,096 Southwest Region 14,363 13,623 28,470 27,090 Non-Mature Communities/Other 38,243 35,409 74,582 67,378 Total consolidated rental income $ 212,764 $ 201,037 $ 419,811 $ 395,437 Reportable apartment home segment NOI Same-Store Communities West Region $ 51,400 $ 46,496 $ 100,999 $ 91,287 Mid-Atlantic Region 30,302 29,863 59,590 58,699 Southeast Region 17,876 16,769 35,207 33,465 Northeast Region 16,269 15,459 31,835 30,004 Southwest Region 8,998 8,263 17,534 16,621 Non-Mature Communities/Other 25,587 23,542 48,842 42,440 Total consolidated NOI 150,432 140,392 294,007 272,516 Reconciling items: Joint venture management and other fees 3,098 2,747 15,804 6,434 Property management (5,851 ) (5,529 ) (11,545 ) (10,875 ) Other operating expenses (1,769 ) (2,171 ) (3,535 ) (4,106 ) Real estate depreciation and amortization (90,344 ) (88,876 ) (179,121 ) (177,409 ) General and administrative (13,721 ) (12,530 ) (25,873 ) (24,524 ) Casualty-related recoveries/(charges), net (843 ) — (1,839 ) (500 ) Other depreciation and amortization (1,700 ) (1,193 ) (3,323 ) (2,273 ) Income/(loss) from unconsolidated entities (573 ) (428 ) 58,586 (3,993 ) Interest expense (29,673 ) (31,691 ) (58,473 ) (64,575 ) Interest income and other income/(expense), net 382 1,426 742 2,841 Tax benefit/(expense), net 1,404 2,230 1,829 5,559 Gain/(loss) on sale of real estate owned, net of tax 79,042 26,709 79,042 51,003 Net (income)/loss attributable to redeemable noncontrolling interests in the Operating Partnership (3,029 ) (1,077 ) (5,617 ) (1,724 ) Net (income)/loss attributable to noncontrolling interests — (2 ) (7 ) (6 ) Net income/(loss) attributable to UDR, Inc. $ 86,855 $ 30,007 $ 160,677 $ 48,368 (a) Same-Store Community population consisted of 35,250 apartment homes. (b) Same-Store Community population consisted of 35,250 apartment homes. The following table details the assets of UDR’s reportable segments as of June 30, 2015 and December 31, 2014 (dollars in thousands) : June 30, December 31, Reportable apartment home segment assets: Same-Store Communities: West Region $ 2,608,586 $ 2,592,156 Mid-Atlantic Region 1,541,420 1,533,993 Southeast Region 738,595 733,068 Northeast Region 1,081,035 1,076,656 Southwest Region 443,526 440,721 Non-Mature Communities/Other 2,012,117 2,006,665 Total assets 8,425,279 8,383,259 Accumulated depreciation (2,557,949 ) (2,434,772 ) Total assets — net book value 5,867,330 5,948,487 Reconciling items: Cash and cash equivalents 2,990 15,224 Restricted cash 22,912 22,340 Deferred financing costs, net 19,930 22,686 Notes receivable, net 15,494 14,369 Investment in and advances to unconsolidated joint ventures, net 914,815 718,226 Other assets 96,259 105,202 Total consolidated assets $ 6,939,730 $ 6,846,534 Capital expenditures related to our Same-Store Communities totaled $20.6 million and $12.8 million for the three months ended June 30, 2015 and 2014 , respectively, and $33.8 million and $20.3 million for the six months ended June 30, 2015 and 2014 , respectively. Capital expenditures related to our Non-Mature Communities/Other totaled $1.2 million and $2.5 million for the three months ended June 30, 2015 and 2014 , respectively, and $3.8 million and $4.8 million for the six months ended June 30, 2015 and 2014 . Markets included in the above geographic segments are as follows: i. West Region — Orange County, San Francisco, Seattle, Los Angeles, Monterey Peninsula, Other Southern California, and Portland ii. Mid-Atlantic Region — Metropolitan D.C., Baltimore, Richmond, Norfolk, and Other Mid-Atlantic iii. Southeast Region — Tampa, Orlando, Nashville, and Other Florida iv. Northeast Region — New York and Boston 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 April 1, 2014 for quarter-to-date comparison and January 1, 2014 for year-to-date comparison and held as of June 30, 2015 . 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 six months ended June 30, 2015 and 2014 . The following table details rental income and NOI from continuing and discontinued operations for the Operating Partnership’s reportable segments for the three and six months ended June 30, 2015 and 2014 , and reconciles NOI to Net income/(loss) attributable to OP unitholders in the Consolidated Statements of Operations (dollars in thousands) : Three Months Ended Six Months Ended June 30, (a) June 30, (b) 2015 2014 2015 2014 Reportable apartment home segment rental income Same-Store Communities West Region $ 48,175 $ 44,544 $ 95,082 $ 87,916 Mid-Atlantic Region 17,613 17,364 34,862 34,610 Southeast Region 11,870 11,254 23,549 22,385 Northeast Region 15,497 14,658 30,570 28,925 Southwest Region 6,868 6,653 13,605 13,206 Non-Mature Communities/Other 13,135 10,369 25,585 20,170 Total consolidated rental income $ 113,158 $ 104,842 $ 223,253 $ 207,212 Reportable apartment home segment NOI Same-Store Communities West Region $ 36,447 $ 32,487 $ 71,094 $ 63,958 Mid-Atlantic Region 11,894 11,900 23,360 23,466 Southeast Region 7,938 7,503 15,648 14,959 Northeast Region 12,074 11,415 23,647 22,053 Southwest Region 4,361 4,168 8,574 8,386 Non-Mature Communities/Other 9,569 7,495 18,075 14,563 Total consolidated NOI 82,283 74,968 160,398 147,385 Reconciling items: Property management (3,112 ) (2,883 ) (6,139 ) (5,698 ) Other operating expenses (1,496 ) (1,451 ) (2,986 ) (2,887 ) Real estate depreciation and amortization (44,100 ) (44,697 ) (88,578 ) (88,968 ) General and administrative (7,032 ) (7,459 ) (12,671 ) (14,429 ) Casualty-related recoveries/(charges), net (280 ) — (873 ) (500 ) Interest expense (10,908 ) (10,159 ) (21,679 ) (20,173 ) Gain/(loss) on sale of real estate owned 32,375 16,285 56,998 40,687 Net (income)/loss attributable to noncontrolling interests (347 ) (178 ) (741 ) (458 ) Net income/(loss) attributable to OP unitholders $ 47,383 $ 24,426 $ 83,729 $ 54,959 (a) Same-Store Community population consisted of 18,969 apartment homes. (b) Same-Store Community population consisted of 18,969 apartment homes The following table details the assets of the Operating Partnership’s reportable segments as of June 30, 2015 and December 31, 2014 (dollars in thousands) : June 30, December 31, 2014 Reportable apartment home segment assets Same-Store Communities West Region $ 1,670,364 $ 1,658,042 Mid-Atlantic Region 716,152 713,093 Southeast Region 335,662 333,428 Northeast Region 780,235 777,376 Southwest Region 230,330 228,996 Non-Mature Communities/Other 506,252 527,835 Total assets 4,238,995 4,238,770 Accumulated depreciation (1,474,834 ) (1,403,303 ) Total assets - net book value 2,764,161 2,835,467 Reconciling items: Cash and cash equivalents 164 502 Restricted cash 14,456 13,811 Deferred financing costs, net 3,707 4,475 Other assets 23,090 24,029 Total consolidated assets $ 2,805,578 $ 2,878,284 Capital expenditures related to the Operating Partnership’s Same-Store Communities totaled $12.5 million and $7.3 million for the three months ended June 30, 2015 and 2014 , respectively, and $20.3 million and $11.2 million for the six months ended June 30, 2015 and 2014 , respectively. Capital expenditures related to the Operating Partnership’s Non-Mature Communities/Other totaled $0.7 million and $0.3 million for the three months ended June 30, 2015 and 2014 , respectively, and $1.2 million and $0.6 million for the six months ended June 30, 2015 and 2014 , respectively. Markets included in the above geographic segments are as follows: i. West Region — Orange County, San Francisco, Seattle, Los Angeles, Monterey Peninsula, Other Southern California, and Portland ii. Mid-Atlantic Region — Metropolitan D.C. and Baltimore iii. Southeast Region — Tampa, Nashville, and Other Florida iv. Northeast Region — New York and Boston v. Southwest Region — Dallas

Significant Accounting Polici38

Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2015
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 six months ended June 30, 2015 and 2014 , 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 $224,000 and $50,000 during the three months ended June 30, 2015 and 2014 , respectively, and $(1,000) and $106,000 during the six months ended June 30, 2015 and 2014 , respectively.
New Accounting Pronouncements, Policy [Policy Text Block]	Recent Accounting Pronouncements In May 2014, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("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, 2018; early adoption is permitted on January 1, 2017. 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. In April 2015, the FASB issued ASU 2015-03, Simplifying the Presentation of Debt Issuance Costs, to revise the presentation of debt issuance costs. Under ASU 2015-03, entities will present debt issuance costs in their balance sheet as a direct deduction from the related debt liability rather than as an asset. Amortization of the deferred costs will continue to be included in interest expense. The guidance, which is to be applied retrospectively to all prior periods, is effective for fiscal years beginning after December 15, 2015, with early adoption permitted for financial statements that have not been previously issued. The Company does not expect ASU 2015-03 to have a significant effect on its consolidated financial statements. In February 2015, the FASB issued ASU 2015-02, Amendments to the Consolidation Analysis, which makes changes to both the variable interest model and the voting model. Among other changes, the new standard specifically eliminates the presumption in the current voting model that a general partner controls a limited partnership or similar entity unless that presumption can be overcome. The new standard will be effective for the Company beginning on January 1, 2016 and early adoption is permitted, including adoption in an interim period. The new standard must be applied using a modified retrospective approach by recording a cumulative-effect adjustment to equity/capital as of the beginning of the period of adoption or retrospectively to each period presented. The Company is currently evaluating the impact of adopting the new standard on its consolidated financial statements. Discontinued Operations In accordance with GAAP, 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. We record sales of real estate that do not meet the definition of a discontinued operation in Gain/(loss) on sale of real estate owned, net of tax on the Consolidated Statements of Operations.
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 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 June 30, 2015 , UDR’s net deferred tax asset was $9.1 million (net of a valuation allowance of less than $0.1 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 June 30, 2015 . UDR and its subsidiaries are subject to federal income tax as well as income tax of various state and local jurisdictions. The tax years 2011 through 2014 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 June 30, 2015 and December 31, 2014 ( dollars in thousands): Interest rate at Balance outstanding June 30, June 30, December 31, 2014 Note due February 2017 (a) 10.00 % $ 12,994 $ 11,869 Note due July 2017 (b) 8.00 % 2,500 2,500 Total notes receivable, net $ 15,494 $ 14,369 (a) The Company has a secured note receivable with an unaffiliated third party with an aggregate commitment of $13.0 million . During the six months ended June 30, 2015 , 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 (February 2017). (b) The Company has a secured note receivable with an unaffiliated third party with an aggregate commitment of $2.5 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). The Company recognized $0.3 million and $1.3 million of interest income from notes receivable during the three months ended June 30, 2015 and 2014 , respectively, and $0.7 million and $2.5 million during the six months ended June 30, 2015 and 2014 , respectively, none of which was related party interest income. Interest income is included in Interest income and other income/(expense), net on the Consolidated Statements of Operations.

Significant Accounting Polici39

Significant Accounting Policies (UNITED DOMINION REALTY, L.P.) (Policies)	6 Months Ended
	Jun. 30, 2015
Entity Information [Line Items]
New Accounting Pronouncements, Policy [Policy Text Block]	Recent Accounting Pronouncements In May 2014, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("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, 2018; early adoption is permitted on January 1, 2017. 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. In April 2015, the FASB issued ASU 2015-03, Simplifying the Presentation of Debt Issuance Costs, to revise the presentation of debt issuance costs. Under ASU 2015-03, entities will present debt issuance costs in their balance sheet as a direct deduction from the related debt liability rather than as an asset. Amortization of the deferred costs will continue to be included in interest expense. The guidance, which is to be applied retrospectively to all prior periods, is effective for fiscal years beginning after December 15, 2015, with early adoption permitted for financial statements that have not been previously issued. The Company does not expect ASU 2015-03 to have a significant effect on its consolidated financial statements. In February 2015, the FASB issued ASU 2015-02, Amendments to the Consolidation Analysis, which makes changes to both the variable interest model and the voting model. Among other changes, the new standard specifically eliminates the presumption in the current voting model that a general partner controls a limited partnership or similar entity unless that presumption can be overcome. The new standard will be effective for the Company beginning on January 1, 2016 and early adoption is permitted, including adoption in an interim period. The new standard must be applied using a modified retrospective approach by recording a cumulative-effect adjustment to equity/capital as of the beginning of the period of adoption or retrospectively to each period presented. The Company is currently evaluating the impact of adopting the new standard on its consolidated financial statements. Discontinued Operations In accordance with GAAP, 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. We record sales of real estate that do not meet the definition of a discontinued operation in Gain/(loss) on sale of real estate owned, net of tax on the Consolidated Statements of Operations.
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 six months ended June 30, 2015 and 2014 , 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 $224,000 and $50,000 during the three months ended June 30, 2015 and 2014 , respectively, and $(1,000) and $106,000 during the six months ended June 30, 2015 and 2014 , 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 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 June 30, 2015 , UDR’s net deferred tax asset was $9.1 million (net of a valuation allowance of less than $0.1 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 June 30, 2015 . UDR and its subsidiaries are subject to federal income tax as well as income tax of various state and local jurisdictions. The tax years 2011 through 2014 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 May 2014, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("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, 2018; early adoption is permitted on January 1, 2017. The Operating Partnership 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. In April 2015, the FASB issued ASU 2015-03, Simplifying the Presentation of Debt Issuance Costs, to revise the presentation of debt issuance costs. Under ASU 2015-03, entities will present debt issuance costs in their balance sheet as a direct deduction from the related debt liability rather than as an asset. Amortization of the deferred costs will continue to be included in interest expense. The guidance, which is to be applied retrospectively to all prior periods, is effective for fiscal years beginning after December 15, 2015, with early adoption permitted for financial statements that have not been previously issued. The Operating Partnership does not expect ASU 2015-03 to have a significant effect on its consolidated financial statements. In February 2015, the FASB issued ASU 2015-02, Amendments to the Consolidation Analysis, which makes changes to both the variable interest model and the voting model. Among other changes, the new standard specifically eliminates the presumption in the current voting model that a general partner controls a limited partnership or similar entity unless that presumption can be overcome. The new standard will be effective for the Operating Partnership beginning on January 1, 2016 and early adoption is permitted, including adoption in an interim period. The new standard must be applied using a modified retrospective approach by recording a cumulative-effect adjustment to equity/capital as of the beginning of the period of adoption or retrospectively to each period presented. The Operating Partnership is currently evaluating the impact of adopting the new standard on its consolidated financial statements. Discontinued Operations In accordance with GAAP, 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. We record sales of real estate that do not meet the definition of a discontinued operation in Gain/(loss) on sale of real estate owned, net of tax on the Consolidated Statements of Operations.
Earnings Per Share, Policy [Policy Text Block]	Income/(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 outstanding during the year. 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.
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 six months ended June 30, 2015 and 2014 , 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 7, 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 ( 2011 through 2014 ) 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.

Significant Accounting Polici40

Significant Accounting Policies (Tables)	6 Months Ended
	Jun. 30, 2015
Accounting Policies [Abstract]
Notes receivable	The following table summarizes our notes receivable, net as of June 30, 2015 and December 31, 2014 ( dollars in thousands): Interest rate at Balance outstanding June 30, June 30, December 31, 2014 Note due February 2017 (a) 10.00 % $ 12,994 $ 11,869 Note due July 2017 (b) 8.00 % 2,500 2,500 Total notes receivable, net $ 15,494 $ 14,369

Real Estate Owned (Tables)

Real Estate Owned (Tables)	6 Months Ended
	Jun. 30, 2015
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 June 30, 2015 and December 31, 2014 (dollars in thousands): June 30, December 31, 2014 Land and land improvements $ 1,919,597 $ 1,980,221 Depreciable property — held and used: Building, improvements, and furniture, fixtures and equipment 6,413,037 6,225,406 Under development: Land and land improvements 78,085 24,584 Building, improvements, and furniture, fixtures and equipment 14,560 153,048 Real estate owned 8,425,279 8,383,259 Accumulated depreciation (2,557,949 ) (2,434,772 ) Real estate owned, net $ 5,867,330 $ 5,948,487

Real Estate Owned (UNITED DOM42

Real Estate Owned (UNITED DOMINION REALTY, L.P.) (Tables)	6 Months Ended
	Jun. 30, 2015
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 June 30, 2015 and December 31, 2014 (dollars in thousands): June 30, December 31, 2014 Land and land improvements $ 1,919,597 $ 1,980,221 Depreciable property — held and used: Building, improvements, and furniture, fixtures and equipment 6,413,037 6,225,406 Under development: Land and land improvements 78,085 24,584 Building, improvements, and furniture, fixtures and equipment 14,560 153,048 Real estate owned 8,425,279 8,383,259 Accumulated depreciation (2,557,949 ) (2,434,772 ) Real estate owned, net $ 5,867,330 $ 5,948,487
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 June 30, 2015 and December 31, 2014 (dollars in thousands) : June 30, December 31, 2014 Land $ 1,006,651 $ 1,008,014 Depreciable property — held and used: Buildings, improvements, and furniture, fixture and equipment 3,232,344 3,230,756 Real estate owned 4,238,995 4,238,770 Accumulated depreciation (1,474,834 ) (1,403,303 ) Real estate owned, net $ 2,764,161 $ 2,835,467

Discontinued Operations (Tables

Discontinued Operations (Tables)	6 Months Ended
	Jun. 30, 2015
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 six months ended June 30, 2015 and 2014 ( dollars in thousands ): Three Months Ended Six Months Ended June 30, June 30, 2015 2014 2015 2014 Rental income $ — $ 78 $ — $ 126 Rental expenses — 89 — 214 Property management — 2 — 3 Interest income and other (income)/expense, net — 9 — 18 Income tax benefit/(expense) — 40 — 40 Income/(loss) from discontinued operations, net of tax $ — $ 18 $ — $ (69 ) Income/(loss) from discontinued operations attributable to UDR, Inc. $ — $ 17 $ — $ (67 )

Joint Ventures (Tables)

Joint Ventures (Tables)	6 Months Ended
	Jun. 30, 2015
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 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 six months ended June 30, 2015 and 2014 . Combined summary balance sheets relating to all of the unconsolidated joint ventures and partnerships (not just our proportionate share) are presented below as of June 30, 2015 and December 31, 2014 ( dollars in thousands ): June 30, December 31, 2014 Total real estate, net $ 3,004,723 $ 2,941,803 Assets held for sale — 216,196 Cash and cash equivalents 36,820 32,544 Other assets 32,869 28,707 Total assets $ 3,074,412 $ 3,219,250 Amount due to UDR $ 6,434 $ 2,997 Third party debt 1,529,724 1,504,477 Liabilities held for sale — 229,706 Accounts payable and accrued liabilities 63,521 44,335 Total liabilities 1,599,679 1,781,515 Total equity 1,474,733 1,437,735 Total liabilities and equity $ 3,074,412 $ 3,219,250 UDR’s investment in unconsolidated joint ventures $ 914,815 $ 718,226
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 June 30, 2015 and December 31, 2014 (dollars in thousands) : Joint Venture Location of Properties Number of Properties Number of Apartment Homes Investment at UDR’s Ownership Interest June 30, June 30, June 30, December 31, June 30, December 31, Operating and development: UDR/MetLife I Various 4 land parcels — $ 14,181 $ 13,306 16.1 % 15.7 % UDR/MetLife II Various 21 operating communities 4,642 428,321 431,277 50.0 % 50.0 % Other UDR/MetLife Development Joint Ventures 1 operating community; 4 development communities (a); Various 1 land parcels 1,437 158,172 134,939 50.6 % 50.6 % UDR/MetLife Vitruvian Park® Addison, TX 3 operating communities 6 land parcels 1,130 75,531 80,302 50.0 % 50.0 % UDR/KFH Washington, D.C. 3 operating communities 660 19,775 21,596 30.0 % 30.0 % Texas (b) Texas — — — (25,901 ) — % 20.0 % Investment in and advances to unconsolidated joint ventures, net, before participating loan investment 695,980,000 695,980 655,519 Income from Investment Investment at Three Months Ended June 30, Six Months Ended June 30, Location Rate Years To Maturity June 30, December 31, 2015 2014 2015 2014 Participating loan investment: Steele Creek Denver, CO 6.5% 2.1 85,208 62,707 $ 1,352 $ 456 $ 2,506 $ 777 Preferred equity investment: West Coast Development Joint Venture (c) Various 6.5% — 133,627 — $ (548 ) $ — $ (548 ) $ — Total investment in and advances to unconsolidated joint ventures, net $ 914,815 $ 718,226 (a) 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 June 30, 2015 , no apartment homes had been completed in Other UDR/MetLife Development Joint Ventures. (b) In January 2015, the eight communities held by the Texas Joint Venture were sold, generating net proceeds to UDR of $43.5 million . The Company recorded promote and disposition fee income of $9.6 million and a gain of $59.1 million (including $24.2 million of previously deferred gains) in connection with the sale.
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 six months ended June 30, 2015 and 2014 ( dollars in thousands ) : Three Months Ended Six Months Ended June 30, June 30, 2015 2014 2015 2014 Total revenues $ 55,450 $ 48,379 $ 109,996 $ 87,334 Property operating expenses (21,557 ) (18,001 ) (41,724 ) (32,360 ) Real estate depreciation and amortization (19,402 ) (16,808 ) (38,754 ) (31,496 ) Operating income/(loss) 14,491 13,570 29,518 23,478 Interest expense (16,169 ) (14,928 ) (32,230 ) (27,079 ) Other income/(expense) (7 ) — (7 ) — Income/(loss) from discontinued operations — (4,705 ) 182,488 (31,688 ) Net income/(loss) $ (1,685 ) $ (6,063 ) $ 179,769 $ (35,289 ) UDR income/(loss) from unconsolidated entities $ (573 ) $ (428 ) $ 58,586 $ (3,993 )
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. Unconsolidated Joint Ventures and Partnerships The Company recognizes income or losses from our investments in unconsolidated joint ventures and partnerships consisting of our proportionate share of the net income 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 June 30, 2015 and December 31, 2014 (dollars in thousands) : Joint Venture Location of Properties Number of Properties Number of Apartment Homes Investment at UDR’s Ownership Interest June 30, June 30, June 30, December 31, June 30, December 31, Operating and development: UDR/MetLife I Various 4 land parcels — $ 14,181 $ 13,306 16.1 % 15.7 % UDR/MetLife II Various 21 operating communities 4,642 428,321 431,277 50.0 % 50.0 % Other UDR/MetLife Development Joint Ventures 1 operating community; 4 development communities (a); Various 1 land parcels 1,437 158,172 134,939 50.6 % 50.6 % UDR/MetLife Vitruvian Park® Addison, TX 3 operating communities 6 land parcels 1,130 75,531 80,302 50.0 % 50.0 % UDR/KFH Washington, D.C. 3 operating communities 660 19,775 21,596 30.0 % 30.0 % Texas (b) Texas — — — (25,901 ) — % 20.0 % Investment in and advances to unconsolidated joint ventures, net, before participating loan investment 695,980,000 695,980 655,519 Income from Investment Investment at Three Months Ended June 30, Six Months Ended June 30, Location Rate Years To Maturity June 30, December 31, 2015 2014 2015 2014 Participating loan investment: Steele Creek Denver, CO 6.5% 2.1 85,208 62,707 $ 1,352 $ 456 $ 2,506 $ 777 Preferred equity investment: West Coast Development Joint Venture (c) Various 6.5% — 133,627 — $ (548 ) $ — $ (548 ) $ — Total investment in and advances to unconsolidated joint ventures, net $ 914,815 $ 718,226 (a) 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 June 30, 2015 , no apartment homes had been completed in Other UDR/MetLife Development Joint Ventures. (b) In January 2015, the eight communities held by the Texas Joint Venture were sold, generating net proceeds to UDR of $43.5 million . The Company recorded promote and disposition fee income of $9.6 million and a gain of $59.1 million (including $24.2 million of previously deferred gains) in connection with the sale. (c) In May 2015, the Company entered into a joint venture agreement with real estate private equity firm, The Wolff Company (“Wolff”), and agreed to pay $136.3 million for a 48 percent interest in a portfolio of five communities that are currently under construction (the "West Coast Development Joint Venture"). As of June 30, 2015, the Company had funded $129.6 million of its investment and had a remaining commitment of $6.7 million . The communities are located in three of the Company’s core, coastal markets: Metro Seattle, Los Angeles and Orange County, CA. UDR earns a 6.5 percent preferred return on its investment through each individual community’s date of stabilization, defined as when a community reaches 80 percent occupancy for ninety consecutive days, while Wolff is allocated all operating income and expense during the pre-stabilization period. Upon stabilization, income and expense will be shared based on each partner’s ownership percentage. The Company will serve as property manager and be paid a management fee during the lease-up phase and subsequent operation of each of the communities. Wolff is the general partner of the joint venture and the developer of the communities. The Company has a fixed price option to acquire Wolff’s remaining interest in each community beginning one year after completion. If the options are exercised for all five communities, the Company’s total price will be $597.4 million . In the event the Company does not exercise its options to purchase at least two communities, Wolff will be entitled to earn a contingent disposition fee equal to 6.5 percent return on its implied equity in the communities not acquired. Wolff is providing certain guaranties and there will be construction loans on all five communities. Once completed, the five communities will contain 1,533 homes. The Company has concluded it does not control the joint venture and accounts for it under the equity method of accounting. The Company's recorded equity investment in the West Coast Development Joint Venture at June 30, 2015 of $133.6 million is inclusive of outside basis costs and our accrued but unpaid preferred return. During the three and six months ended June 30, 2015 , the Company earned a preferred return of $1.0 million , offset by its share of the West Coast Development Joint Venture transaction expenses of $1.5 million . As of June 30, 2015 and December 31, 2014 , the Company had deferred fees and deferred profit from the sale of properties to joint ventures or partnerships of $6.8 million and $28.5 million , respectively, which will be recognized through income 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 $2.6 million and $2.3 million for the three months ended June 30, 2015 and 2014 , respectively, and $5.2 million and $5.6 million for the six months ended June 30, 2015 and 2014 , 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 six months ended June 30, 2015 and 2014 . Combined summary balance sheets relating to all of the unconsolidated joint ventures and partnerships (not just our proportionate share) are presented below as of June 30, 2015 and December 31, 2014 ( dollars in thousands ): June 30, December 31, 2014 Total real estate, net $ 3,004,723 $ 2,941,803 Assets held for sale — 216,196 Cash and cash equivalents 36,820 32,544 Other assets 32,869 28,707 Total assets $ 3,074,412 $ 3,219,250 Amount due to UDR $ 6,434 $ 2,997 Third party debt 1,529,724 1,504,477 Liabilities held for sale — 229,706 Accounts payable and accrued liabilities 63,521 44,335 Total liabilities 1,599,679 1,781,515 Total equity 1,474,733 1,437,735 Total liabilities and equity $ 3,074,412 $ 3,219,250 UDR’s investment in unconsolidated joint ventures $ 914,815 $ 718,226 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 six months ended June 30, 2015 and 2014 ( dollars in thousands ) : Three Months Ended Six Months Ended June 30, June 30, 2015 2014 2015 2014 Total revenues $ 55,450 $ 48,379 $ 109,996 $ 87,334 Property operating expenses (21,557 ) (18,001 ) (41,724 ) (32,360 ) Real estate depreciation and amortization (19,402 ) (16,808 ) (38,754 ) (31,496 ) Operating income/(loss) 14,491 13,570 29,518 23,478 Interest expense (16,169 ) (14,928 ) (32,230 ) (27,079 ) Other income/(expense) (7 ) — (7 ) — Income/(loss) from discontinued operations — (4,705 ) 182,488 (31,688 ) Net income/(loss) $ (1,685 ) $ (6,063 ) $ 179,769 $ (35,289 ) UDR income/(loss) from unconsolidated entities $ (573 ) $ (428 ) $ 58,586 $ (3,993 )

Secured and Unsecured Debt (Tab

Secured and Unsecured Debt (Tables)	6 Months Ended
	Jun. 30, 2015
Debt Disclosure [Abstract]
Secured debt instruments	The following is a summary of our secured and unsecured debt at June 30, 2015 and December 31, 2014 ( dollars in thousands ): Six Months Ended Principal Outstanding June 30, 2015 June 30, December 31, 2014 Weighted Average Interest Rate Weighted Average Years to Maturity Number of Communities Encumbered Secured Debt: Fixed Rate Debt Mortgage notes payable (a) $ 408,736 $ 401,210 5.50 % 1.1 7 Fannie Mae credit facilities (b) 566,288 568,086 5.12 % 3.5 21 Total fixed rate secured debt 975,024 969,296 5.28 % 2.5 28 Variable Rate Debt Mortgage notes payable 31,337 31,337 1.94 % 1.6 1 Tax-exempt secured notes payable (c) 94,700 94,700 0.84 % 7.7 2 Fannie Mae credit facilities (b) 249,378 266,196 1.63 % 4.8 7 Total variable rate secured debt 375,415 392,233 1.45 % 5.3 10 Total Secured Debt 1,350,439 1,361,529 4.22 % 3.3 38 Unsecured Debt: Commercial Banks Borrowings outstanding under an unsecured credit facility due December 2017 (d) (f) 457,000 152,500 1.12 % 2.4 Senior Unsecured Notes 5.25% Medium-Term Notes due January 2015 (net of discounts of $0 and $6, respectively) (e) — 325,169 — % — 5.25% Medium-Term Notes due January 2016 83,260 83,260 5.25 % 0.5 6.21% Term Notes due July 2016 12,609 — 6.21 % 1.0 4.25% Medium-Term Notes due June 2018 (net of discounts of $1,251 and $1,465, respectively) (f) 298,749 298,535 4.25 % 2.9 1.70% Term Notes due June 2018 (f) 215,000 215,000 1.70 % 2.9 1.53% Term Notes due June 2018 (f) 100,000 100,000 1.53 % 2.9 1.33% Term Notes due June 2018 (f) 35,000 35,000 1.33 % 2.9 3.70% Medium-Term Notes due October 2020 (net of discounts of $42 and $46, respectively) (f) 299,958 299,954 3.70 % 5.3 4.63% Medium-Term Notes due January 2022 (net of discounts of $2,344 and $2,523, respectively) (f) 397,656 397,477 4.63 % 6.5 3.75% Medium-Term Notes due July 2024 (net of discount of $938 and $990, respectively) (f) 299,062 299,010 3.75 % 9.0 8.50% Debentures due September 2024 15,644 15,644 8.50 % 9.2 Other 26 27 N/A N/A Total Unsecured Debt 2,213,964 2,221,576 3.20 % 4.6 Total Debt $ 3,564,403 $ 3,583,105 3.58 % 4.1
Secured credit facilities	Further information related to these credit facilities is as follows (dollars in thousands) : June 30, December 31, 2014 Borrowings outstanding $ 815,666 $ 834,282 Weighted average borrowings during the period ended 830,434 835,873 Maximum daily borrowings during the period ended 834,003 837,564 Weighted average interest rate during the period ended 4.0 % 4.1 % Weighted average interest rate at the end of the period 4.1 % 4.0 %
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 June 30, 2015 are as follows (dollars in thousands): Year Total Fixed Secured Debt Total Variable Secured Debt Total Secured Debt Total Unsecured Debt (a) Total Debt 2015 $ 191,363 $ — $ 191,363 $ 79 $ 191,442 2016 148,223 — 148,223 94,469 242,692 2017 177,882 96,337 274,219 457,000 731,219 2018 121,685 87,969 209,654 648,445 858,099 2019 245,871 67,700 313,571 — 313,571 Thereafter 90,000 123,409 213,409 1,013,971 1,227,380 Total $ 975,024 $ 375,415 $ 1,350,439 $ 2,213,964 $ 3,564,403

Debt (UNITED DOMINION REALTY,46

Debt (UNITED DOMINION REALTY, L.P.) (Tables)	6 Months Ended
	Jun. 30, 2015
Entity Information [Line Items]
Secured debt instruments	The following is a summary of our secured and unsecured debt at June 30, 2015 and December 31, 2014 ( dollars in thousands ): Six Months Ended Principal Outstanding June 30, 2015 June 30, December 31, 2014 Weighted Average Interest Rate Weighted Average Years to Maturity Number of Communities Encumbered Secured Debt: Fixed Rate Debt Mortgage notes payable (a) $ 408,736 $ 401,210 5.50 % 1.1 7 Fannie Mae credit facilities (b) 566,288 568,086 5.12 % 3.5 21 Total fixed rate secured debt 975,024 969,296 5.28 % 2.5 28 Variable Rate Debt Mortgage notes payable 31,337 31,337 1.94 % 1.6 1 Tax-exempt secured notes payable (c) 94,700 94,700 0.84 % 7.7 2 Fannie Mae credit facilities (b) 249,378 266,196 1.63 % 4.8 7 Total variable rate secured debt 375,415 392,233 1.45 % 5.3 10 Total Secured Debt 1,350,439 1,361,529 4.22 % 3.3 38 Unsecured Debt: Commercial Banks Borrowings outstanding under an unsecured credit facility due December 2017 (d) (f) 457,000 152,500 1.12 % 2.4 Senior Unsecured Notes 5.25% Medium-Term Notes due January 2015 (net of discounts of $0 and $6, respectively) (e) — 325,169 — % — 5.25% Medium-Term Notes due January 2016 83,260 83,260 5.25 % 0.5 6.21% Term Notes due July 2016 12,609 — 6.21 % 1.0 4.25% Medium-Term Notes due June 2018 (net of discounts of $1,251 and $1,465, respectively) (f) 298,749 298,535 4.25 % 2.9 1.70% Term Notes due June 2018 (f) 215,000 215,000 1.70 % 2.9 1.53% Term Notes due June 2018 (f) 100,000 100,000 1.53 % 2.9 1.33% Term Notes due June 2018 (f) 35,000 35,000 1.33 % 2.9 3.70% Medium-Term Notes due October 2020 (net of discounts of $42 and $46, respectively) (f) 299,958 299,954 3.70 % 5.3 4.63% Medium-Term Notes due January 2022 (net of discounts of $2,344 and $2,523, respectively) (f) 397,656 397,477 4.63 % 6.5 3.75% Medium-Term Notes due July 2024 (net of discount of $938 and $990, respectively) (f) 299,062 299,010 3.75 % 9.0 8.50% Debentures due September 2024 15,644 15,644 8.50 % 9.2 Other 26 27 N/A N/A Total Unsecured Debt 2,213,964 2,221,576 3.20 % 4.6 Total Debt $ 3,564,403 $ 3,583,105 3.58 % 4.1
Secured credit facilities	Further information related to these credit facilities is as follows (dollars in thousands) : June 30, December 31, 2014 Borrowings outstanding $ 815,666 $ 834,282 Weighted average borrowings during the period ended 830,434 835,873 Maximum daily borrowings during the period ended 834,003 837,564 Weighted average interest rate during the period ended 4.0 % 4.1 % Weighted average interest rate at the end of the period 4.1 % 4.0 %
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 June 30, 2015 are as follows (dollars in thousands): Year Total Fixed Secured Debt Total Variable Secured Debt Total Secured Debt Total Unsecured Debt (a) Total Debt 2015 $ 191,363 $ — $ 191,363 $ 79 $ 191,442 2016 148,223 — 148,223 94,469 242,692 2017 177,882 96,337 274,219 457,000 731,219 2018 121,685 87,969 209,654 648,445 858,099 2019 245,871 67,700 313,571 — 313,571 Thereafter 90,000 123,409 213,409 1,013,971 1,227,380 Total $ 975,024 $ 375,415 $ 1,350,439 $ 2,213,964 $ 3,564,403
United Dominion Reality L.P. [Member]
Entity Information [Line Items]
Secured debt instruments	Secured debt consists of the following as of June 30, 2015 and December 31, 2014 ( dollars in thousands ): Six Months Ended Principal Outstanding June 30, 2015 June 30, December 31, 2014 Weighted Average Interest Rate Weighted Average Years to Maturity Number of Communities Encumbered Fixed Rate Debt Mortgage notes payable $ 374,056 $ 378,371 5.49 % 1.1 5 Fannie Mae credit facilities 334,002 333,828 4.90 % 4.1 9 Total fixed rate secured debt 708,058 712,199 5.21 % 2.5 14 Variable Rate Debt Tax-exempt secured note payable 27,000 27,000 0.85 % 16.7 1 Fannie Mae credit facilities 177,509 192,760 1.88 % 5.7 5 Total variable rate secured debt 204,509 219,760 1.74 % 7.1 6 Total Secured Debt $ 912,567 $ 931,959 4.43 % 3.5 20
Secured credit facilities	The following information relates to the credit facilities allocated to the Operating Partnership (dollars in thousands) : June 30, December 31, 2014 Borrowings outstanding $ 511,511 $ 526,588 Weighted average borrowings during the period ended 520,773 527,592 Maximum daily borrowings during the period 523,011 528,659 Weighted average interest rate during the period ended 3.8 % 4.1 % Interest rate at the end of the period 3.9 % 4.0 %
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 June 30, 2015 are as follows (dollars in thousands): Fixed Variable Year Mortgage Notes Payable Secured Credit Facilities Tax-Exempt Secured Notes Payable Secured Credit Facilities Total 2015 $ 188,759 $ 184 $ — $ — $ 188,943 2016 131,946 385 — — 132,331 2017 1,630 15,640 — 6,566 23,836 2018 1,685 111,256 — 81,559 194,500 2019 50,036 123,095 — — 173,131 Thereafter — 83,442 27,000 89,384 199,826 Total $ 374,056 $ 334,002 $ 27,000 $ 177,509 $ 912,567

Income_(Loss) Per Share (Tables

Income/(Loss) Per Share (Tables)	6 Months Ended
	Jun. 30, 2015
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 six months ended June 30, 2015 and 2014 (shares in thousands) : Three Months Ended Six Months Ended June 30, June 30, 2015 2014 2015 2014 OP Units 9,125 9,316 9,145 9,317 Preferred stock 3,036 3,036 3,036 3,036 Stock options and unvested restricted stock 1,921 1,936 1,923 1,875
(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 Six Months Ended June 30, June 30, 2015 2014 2015 2014 Numerator for income/(loss) per share: Income/(loss) from continuing operations $ 10,842 $ 4,359 $ 87,259 $ (836 ) Gain/(loss) on sale of real estate owned, net of tax 79,042 26,709 79,042 51,003 (Income)/loss from continuing operations attributable to redeemable noncontrolling interests in the Operating Partnership (3,029 ) (1,076 ) (5,617 ) (1,726 ) (Income)/loss from continuing operations attributable to noncontrolling interests — (2 ) (7 ) (6 ) Income/(loss) from continuing operations attributable to UDR, Inc. 86,855 29,990 160,677 48,435 Distributions to preferred stockholders - Series E (Convertible) (931 ) (931 ) (1,862 ) (1,862 ) Income/(loss) from continuing operations attributable to common stockholders - basic $ 85,924 $ 29,059 $ 158,815 $ 46,573 Dilutive distributions to preferred stockholders - Series E (Convertible) 931 — — — Income/(loss) from continuing operations attributable to common stockholders - diluted $ 86,855 $ 29,059 $ 158,815 $ 46,573 Income/(loss) from discontinued operations, net of tax $ — $ 18 $ — $ (69 ) (Income)/loss from discontinued operations attributable to redeemable noncontrolling interests in the Operating Partnership — (1 ) — 2 Income/(loss) from discontinued operations attributable to common stockholders $ — $ 17 $ — $ (67 ) Net income/(loss) attributable to common stockholders 85,924 29,076 $ 158,815 $ 46,506 Denominator for income/(loss) per share: Weighted average common shares outstanding 259,028 251,458 258,567 251,336 Non-vested restricted stock awards (1,179 ) (1,203 ) (1,223 ) (1,120 ) Denominator for basic income/(loss) per share 257,849 250,255 257,344 250,216 Incremental shares issuable from assumed conversion of preferred stock, stock options, and unvested restricted stock 4,957 1,936 1,923 1,875 Denominator for diluted income/(loss) per share 262,806 252,191 259,267 252,091 Income/(loss) per weighted average common share-basic: Income/(loss) from continuing operations attributable to common stockholders $ 0.33 $ 0.12 $ 0.62 $ 0.19 Income/(loss) from discontinued operations attributable to common stockholders — — — — Net income/(loss) attributable to common stockholders $ 0.33 $ 0.12 $ 0.62 $ 0.19 Income/(loss) per weighted average common share-diluted: Income/(loss) from continuing operations attributable to common stockholders $ 0.33 $ 0.12 $ 0.61 $ 0.18 Income/(loss) from discontinued operations attributable to common stockholders — — — — Net income/(loss) attributable to common stockholders $ 0.33 $ 0.12 $ 0.61 $ 0.18

Noncontrolling Interests (Table

Noncontrolling Interests (Tables)	6 Months Ended
	Jun. 30, 2015
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, 2014 $ 282,480 Mark-to-market adjustment to redeemable noncontrolling interests in the Operating Partnership 10,930 Conversion of OP Units to Common Stock (3,498 ) Net income/(loss) attributable to redeemable noncontrolling interests in the Operating Partnership 5,617 Distributions to redeemable noncontrolling interests in the Operating Partnership (5,250 ) Allocation of other comprehensive income/(loss) (1 ) Redeemable noncontrolling interests in the Operating Partnership, June 30, 2015 $ 290,278 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 Six Months Ended June 30, June 30, 2015 2014 2015 2014 Net income/(loss) attributable to common stockholders $ 85,924 $ 29,076 $ 158,815 $ 46,506 Conversion of OP Units to UDR Common stock 3,479 191 3,498 191 Change in equity from net income/(loss) attributable to common stockholders and conversion of OP Units to UDR Common Stock $ 89,403 $ 29,267 $ 162,313 $ 46,697

Fair Value of Derivatives and49

Fair Value of Derivatives and Financial Instruments (Tables)	6 Months Ended
	Jun. 30, 2015
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 June 30, 2015 and December 31, 2014 are summarized as follows (dollars in thousands) : Fair Value at June 30, 2015, Using Total Carrying Amount in Statement of Financial Position at June 30, 2015 Fair Value Estimate at June 30, 2015 Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Description: Notes receivable (a) $ 15,494 $ 15,863 $ — $ — $ 15,863 Derivatives - Interest rate contracts (b) 12 12 — 12 — Total assets $ 15,506 $ 15,875 $ — $ 12 $ 15,863 Derivatives - Interest rate contracts (b) $ 9,109 $ 9,109 $ — $ 9,109 $ — Secured debt instruments - fixed rate: (c) Mortgage notes payable 408,736 420,571 — — 420,571 Fannie Mae credit facilities 566,288 592,916 — — 592,916 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 249,378 249,378 — — 249,378 Unsecured debt instruments: (c) Commercial bank 457,000 457,000 — — 457,000 Senior unsecured notes 1,756,964 1,816,636 — — 1,816,636 Total liabilities $ 3,573,512 $ 3,671,647 $ — $ 9,109 $ 3,662,538 Redeemable noncontrolling interests in the Operating Partnership (d) $ 290,278 $ 290,278 $ — $ 290,278 $ — Fair Value at December 31, 2014, Using Total Carrying Amount in Statement of Financial Position at December 31, 2014 Fair Value Estimate at December 31, 2014 Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Description: Notes receivable (a) $ 14,369 $ 14,808 $ — $ — $ 14,808 Derivatives - Interest rate contracts (b) 88 88 — 88 — Total assets $ 14,457 $ 14,896 $ — $ 88 $ 14,808 Derivatives- Interest rate contracts (b) $ 10,368 $ 10,368 $ — $ 10,368 $ — Secured debt instruments - fixed rate: (c) Mortgage notes payable 401,210 415,663 — — 415,663 Fannie Mae credit facilities 568,086 606,623 — — 606,623 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 266,196 266,196 — — 266,196 Unsecured debt instruments: (c) Commercial bank 152,500 152,500 — — 152,500 Senior unsecured notes 2,069,076 2,144,125 — — 2,144,125 Total liabilities $ 3,593,473 $ 3,721,512 $ — $ 10,368 $ 3,711,144 Redeemable noncontrolling interests in the Operating Partnership (d) $ 282,480 $ 282,480 $ — $ 282,480 $ — (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 and50

Fair Value of Derivatives and Financial Instruments (UNITED DOMINION REALTY, L.P.) (Tables)	6 Months Ended
	Jun. 30, 2015
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 June 30, 2015 and December 31, 2014 are summarized as follows (dollars in thousands) : Fair Value at June 30, 2015, Using Total Carrying Amount in Statement of Financial Position at June 30, 2015 Fair Value Estimate at June 30, 2015 Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Description: Notes receivable (a) $ 15,494 $ 15,863 $ — $ — $ 15,863 Derivatives - Interest rate contracts (b) 12 12 — 12 — Total assets $ 15,506 $ 15,875 $ — $ 12 $ 15,863 Derivatives - Interest rate contracts (b) $ 9,109 $ 9,109 $ — $ 9,109 $ — Secured debt instruments - fixed rate: (c) Mortgage notes payable 408,736 420,571 — — 420,571 Fannie Mae credit facilities 566,288 592,916 — — 592,916 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 249,378 249,378 — — 249,378 Unsecured debt instruments: (c) Commercial bank 457,000 457,000 — — 457,000 Senior unsecured notes 1,756,964 1,816,636 — — 1,816,636 Total liabilities $ 3,573,512 $ 3,671,647 $ — $ 9,109 $ 3,662,538 Redeemable noncontrolling interests in the Operating Partnership (d) $ 290,278 $ 290,278 $ — $ 290,278 $ — Fair Value at December 31, 2014, Using Total Carrying Amount in Statement of Financial Position at December 31, 2014 Fair Value Estimate at December 31, 2014 Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Description: Notes receivable (a) $ 14,369 $ 14,808 $ — $ — $ 14,808 Derivatives - Interest rate contracts (b) 88 88 — 88 — Total assets $ 14,457 $ 14,896 $ — $ 88 $ 14,808 Derivatives- Interest rate contracts (b) $ 10,368 $ 10,368 $ — $ 10,368 $ — Secured debt instruments - fixed rate: (c) Mortgage notes payable 401,210 415,663 — — 415,663 Fannie Mae credit facilities 568,086 606,623 — — 606,623 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 266,196 266,196 — — 266,196 Unsecured debt instruments: (c) Commercial bank 152,500 152,500 — — 152,500 Senior unsecured notes 2,069,076 2,144,125 — — 2,144,125 Total liabilities $ 3,593,473 $ 3,721,512 $ — $ 10,368 $ 3,711,144 Redeemable noncontrolling interests in the Operating Partnership (d) $ 282,480 $ 282,480 $ — $ 282,480 $ — (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 June 30, 2015 and December 31, 2014 are summarized as follows (dollars in thousands) : Fair Value at June 30, 2015, Using Total Carrying Amount in Statement of Financial Position at June 30, 2015 Fair Value Estimate at June 30, 2015 Quoted Prices in Significant Significant Description: Derivatives - Interest rate contracts (a) $ 7 $ 7 $ — $ 7 $ — Total assets $ 7 $ 7 $ — $ 7 $ — Derivatives - Interest rate contracts (a) $ 436 $ 436 $ — $ 436 $ — Secured debt instruments - fixed rate: (b) Mortgage notes payable 374,056 384,909 — — 384,909 Fannie Mae credit facilities 334,002 349,634 — — 349,634 Secured debt instruments - variable rate: (b) Tax-exempt secured notes payable 27,000 27,000 — — 27,000 Fannie Mae credit facilities 177,509 177,509 — — 177,509 Total liabilities $ 913,003 $ 939,488 $ — $ 436 $ 939,052 Fair Value at December 31, 2014, Using Total Carrying Amount in Statement of Financial Position at December 31, 2014 Fair Value Estimate at December 31, 2014 Quoted Prices in Significant Significant Description: Derivatives - Interest rate contracts (a) $ 39 $ 39 $ — $ 39 $ — Total assets $ 39 $ 39 $ — $ 39 $ — Derivatives - Interest rate contracts (a) $ 918 $ 918 $ — $ 918 $ — Secured debt instruments - fixed rate: (b) Mortgage notes payable 378,371 391,835 — — 391,835 Fannie Mae credit facilities 333,828 355,470 — — 355,470 Secured debt instruments - variable rate: (b) Tax-exempt secured notes payable 27,000 27,000 — — 27,000 Fannie Mae credit facilities 192,760 192,760 — — 192,760 Total liabilities $ 932,877 $ 967,983 $ — $ 918 $ 967,065 (a) See Note 7, Derivatives and Hedging Activity. (b) See Note 4, Debt.

Derivatives and Hedging Activ51

Derivatives and Hedging Activity (Tables)	6 Months Ended
	Jun. 30, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Outstanding interest rate derivatives	As of June 30, 2015 , 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 9 $ 565,000 Interest rate caps 2 $ 219,984 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 six months ended June 30, 2015 and 2014 . As of June 30, 2015 , the Company had the following outstanding derivatives that were not designated as hedges in qualifying hedging relationships ( dollars in thousands ): Product Number of Instruments Notional Interest rate caps 2 $ 116,289
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 June 30, 2015 and December 31, 2014 ( dollars in thousands ): Asset Derivatives (included in Other assets ) Liability Derivatives (included in Other liabilities ) Fair Value at: Fair Value at: June 30, December 31, June 30, December 31, Derivatives designated as hedging instruments: Interest rate products $ 9 86 $ 9,109 $ 10,368 Derivatives not designated as hedging instruments: Interest rate products $ 3 $ 2 $ — $ —
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 six months ended June 30, 2015 and 2014 ( dollars in thousands ): Derivatives in Cash Flow Hedging Relationships Unrealized holding gain/(loss) Recognized in OCI (Effective Portion) Gain/(Loss) Reclassified from Accumulated OCI into Interest expense (Effective Portion) Gain/(Loss) Recognized in Interest expense (Ineffective Portion and Amount Excluded from Effectiveness Testing) 2015 2014 2015 2014 2015 2014 Three Months Ended June 30, Interest rate products $ 6,186 $ 304 $ (292 ) $ (1,145 ) $ — $ 3 Six Months Ended June 30, Interest rate products $ (1,366 ) $ 249 $ (1,029 ) $ (2,677 ) $ — $ 3
Effect of Company's derivatives not designated as hedging instruments on the Consolidated Statements of Operations	Gain/(Loss) Recognized in Interest income and other income/(expense), net Derivatives Not Designated as Hedging Instruments 2015 2014 Three Months Ended June 30, Interest rate products $ (22 ) $ — Six Months Ended June 30, Interest rate products $ (24 ) $ —
Offsetting Assets [Table Text Block]	Offsetting of Derivative Assets Gross Amounts of Recognized Assets Gross Amounts Offset in the Consolidated Balance Sheets Net Amounts of Assets Presented in the Consolidated Balance Sheets (a) Gross Amounts Not Offset in the Consolidated Balance Sheets Financial Instruments Cash Collateral Received Net Amount June 30, 2015 $ 12 $ — $ 12 $ — $ — $ 12 December 31, 2014 $ 88 $ — $ 88 $ (27 ) $ — $ 61 (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 of Recognized Liabilities Gross Amounts Offset in the Consolidated Balance Sheets Net Amounts of Liabilities Presented in the Consolidated Balance Sheets (b) Gross Amounts Not Offset in the Consolidated Balance Sheets Financial Instruments Cash Collateral Posted Net Amount June 30, 2015 $ 9,109 $ — $ 9,109 $ — $ — $ 9,109 December 31, 2014 $ 10,368 $ — $ 10,368 $ (27 ) $ — $ 10,341 (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 Activ52

Derivatives and Hedging Activity (UNITED DOMINION REALTY, L.P.) (Tables)	6 Months Ended
	Jun. 30, 2015
Entity Information [Line Items]
Outstanding interest rate derivatives	As of June 30, 2015 , 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 9 $ 565,000 Interest rate caps 2 $ 219,984 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 six months ended June 30, 2015 and 2014 . As of June 30, 2015 , the Company had the following outstanding derivatives that were not designated as hedges in qualifying hedging relationships ( dollars in thousands ): Product Number of Instruments Notional Interest rate caps 2 $ 116,289
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 June 30, 2015 and December 31, 2014 ( dollars in thousands ): Asset Derivatives (included in Other assets ) Liability Derivatives (included in Other liabilities ) Fair Value at: Fair Value at: June 30, December 31, June 30, December 31, Derivatives designated as hedging instruments: Interest rate products $ 9 86 $ 9,109 $ 10,368 Derivatives not designated as hedging instruments: Interest rate products $ 3 $ 2 $ — $ —
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 six months ended June 30, 2015 and 2014 ( dollars in thousands ): Derivatives in Cash Flow Hedging Relationships Unrealized holding gain/(loss) Recognized in OCI (Effective Portion) Gain/(Loss) Reclassified from Accumulated OCI into Interest expense (Effective Portion) Gain/(Loss) Recognized in Interest expense (Ineffective Portion and Amount Excluded from Effectiveness Testing) 2015 2014 2015 2014 2015 2014 Three Months Ended June 30, Interest rate products $ 6,186 $ 304 $ (292 ) $ (1,145 ) $ — $ 3 Six Months Ended June 30, Interest rate products $ (1,366 ) $ 249 $ (1,029 ) $ (2,677 ) $ — $ 3
Effect of Company's derivatives not designated as hedging instruments on the Consolidated Statements of Operations	Gain/(Loss) Recognized in Interest income and other income/(expense), net Derivatives Not Designated as Hedging Instruments 2015 2014 Three Months Ended June 30, Interest rate products $ (22 ) $ — Six Months Ended June 30, Interest rate products $ (24 ) $ —
Offsetting Assets [Table Text Block]	Offsetting of Derivative Assets Gross Amounts of Recognized Assets Gross Amounts Offset in the Consolidated Balance Sheets Net Amounts of Assets Presented in the Consolidated Balance Sheets (a) Gross Amounts Not Offset in the Consolidated Balance Sheets Financial Instruments Cash Collateral Received Net Amount June 30, 2015 $ 12 $ — $ 12 $ — $ — $ 12 December 31, 2014 $ 88 $ — $ 88 $ (27 ) $ — $ 61 (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 of Recognized Liabilities Gross Amounts Offset in the Consolidated Balance Sheets Net Amounts of Liabilities Presented in the Consolidated Balance Sheets (b) Gross Amounts Not Offset in the Consolidated Balance Sheets Financial Instruments Cash Collateral Posted Net Amount June 30, 2015 $ 9,109 $ — $ 9,109 $ — $ — $ 9,109 December 31, 2014 $ 10,368 $ — $ 10,368 $ (27 ) $ — $ 10,341 (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 June 30, 2015 , 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 1 $ 46,357 Interest rate caps 1 $ 143,508 Derivatives not designated as hedges are not speculative and are used to manage the Operating Partnership’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 six months ended June 30, 2015 and 2014 . As of June 30, 2015 , we had the following outstanding derivatives that were not designated as a hedges in a qualifying hedging relationships ( dollars in thousands ): Product Number of Instruments Notional Interest rate caps 2 $ 109,264 As of June 30, 2015 , 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 1 $ 46,357 Interest rate caps 1 $ 143,508 Derivatives not designated as hedges are not speculative and are used to manage the Operating Partnership’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 six months ended June 30, 2015 and 2014 . As of June 30, 2015 , we had the following outstanding derivatives that were not designated as a hedges in a qualifying hedging relationships ( dollars in thousands ): Product Number of Instruments Notional Interest rate caps 2 $ 109,264
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 June 30, 2015 and December 31, 2014 ( dollars in thousands ): Asset Derivatives (included in Other assets ) Liability Derivatives (included in Other liabilities ) Fair Value at: Fair Value at: June 30, December 31, June 30, December 31, Derivatives designated as hedging instruments: Interest rate products $ 4 $ 37 $ 436 $ 918 Derivatives not designated as hedging instruments: Interest rate products $ 3 $ 2 $ — $ —
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 six months ended June 30, 2015 and 2014 ( dollars in thousands ): Unrealized holding gain/(loss) Recognized in OCI (Effective Portion) Gain/(Loss) Reclassified from Accumulated OCI into Interest expense (Effective Portion) Derivatives in Cash Flow Hedging Relationships 2015 2014 2015 2014 Three Months Ended June 30, Interest rate products $ (26 ) $ (140 ) $ (267 ) $ (573 ) Six Months Ended June 30, Interest rate products $ (77 ) $ (191 ) $ (553 ) $ (1,196 )
Effect of Company's derivatives not designated as hedging instruments on the Consolidated Statements of Operations	Gain/(Loss) Recognized in Interest income and other income/(expense), net Derivatives Not Designated as Hedging Instruments 2015 2014 Three Months Ended June 30, Interest rate products $ (22 ) $ — Six Months Ended June 30, Interest rate products $ (23 ) $ —
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 June 30, 2015 and December 31, 2014 : Offsetting of Derivative Assets Gross Amounts of Recognized Assets Gross Amounts Offset in the Consolidated Balance Sheets Net Amounts of Assets Presented in the Consolidated Balance Sheets (a) Gross Amounts Not Offset in the Consolidated Balance Sheets Financial Instruments Cash Collateral Received Net Amount June 30, 2015 $ 7 $ — $ 7 $ — $ — $ 7 December 31, 2014 $ 39 $ — $ 39 $ — $ — $ 39 (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 of Recognized Liabilities Gross Amounts Offset in the Consolidated Balance Sheets Net Amounts of Liabilities Presented in the Consolidated Balance Sheets (b) Gross Amounts Not Offset in the Consolidated Balance Sheets Financial Instruments Cash Collateral Posted Net Amount June 30, 2015 $ 436 $ — $ 436 $ — $ — $ 436 December 31, 2014 $ 918 $ — $ 918 $ — $ — $ 918 (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 Contingencies53

Commitments and Contingencies (Tables)	6 Months Ended
	Jun. 30, 2015
Commitments and Contingencies Disclosure [Abstract]
Real estate commitments	The following summarizes the Company’s real estate commitments at June 30, 2015 ( dollars in thousands ): Number of Properties Costs Incurred as of June 30, 2015 (a) Expected Costs to Complete Average Ownership Stake Wholly-owned — under development 1 $ 92,645 (b) $ 249,355 100 % Wholly-owned — redevelopment 1 4,854 (b) 10,146 100 % Joint ventures: Unconsolidated joint ventures 4 335,539 163,791 (c) Various Participating loan investments 1 85,208 (d) 6,801 (e) 0 % Preferred equity investments 5 129,592 (f) 6,735 (g) 48 % $ 647,838 $ 436,828 (a) Represents 100% of project costs incurred as of June 30, 2015 . (b) Costs incurred to date include $114,000 and $1.3 million of accrued fixed assets for development and redevelopment, respectively. (c) Represents UDR’s proportionate share of expected remaining costs to complete. (d) Represents the participating loan balance funded as of June 30, 2015 . (e) Represents UDR’s remaining participating loan commitment for Steele Creek. (f) Represents UDR's share of capital contributed to the West Coast Development Joint Venture as of June 30, 2015 . (g) Represents UDR's remaining funding commitment on Katella Grand II.

Reportable Segment (Tables)

Reportable Segment (Tables)	6 Months Ended
	Jun. 30, 2015
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 six months ended June 30, 2015 and 2014 , and reconciles NOI to Net Income/(Loss) Attributable to UDR, Inc . in the Consolidated Statements of Operations (dollars in thousands) : Three Months Ended Six Months Ended June 30, (a) June 30, (b) 2015 2014 2015 2014 Reportable apartment home segment rental income Same-Store Communities West Region $ 68,646 $ 64,004 $ 135,595 $ 126,405 Mid-Atlantic Region 43,536 42,644 86,331 84,694 Southeast Region 26,540 25,063 52,505 49,774 Northeast Region 21,436 20,294 42,328 40,096 Southwest Region 14,363 13,623 28,470 27,090 Non-Mature Communities/Other 38,243 35,409 74,582 67,378 Total consolidated rental income $ 212,764 $ 201,037 $ 419,811 $ 395,437 Reportable apartment home segment NOI Same-Store Communities West Region $ 51,400 $ 46,496 $ 100,999 $ 91,287 Mid-Atlantic Region 30,302 29,863 59,590 58,699 Southeast Region 17,876 16,769 35,207 33,465 Northeast Region 16,269 15,459 31,835 30,004 Southwest Region 8,998 8,263 17,534 16,621 Non-Mature Communities/Other 25,587 23,542 48,842 42,440 Total consolidated NOI 150,432 140,392 294,007 272,516 Reconciling items: Joint venture management and other fees 3,098 2,747 15,804 6,434 Property management (5,851 ) (5,529 ) (11,545 ) (10,875 ) Other operating expenses (1,769 ) (2,171 ) (3,535 ) (4,106 ) Real estate depreciation and amortization (90,344 ) (88,876 ) (179,121 ) (177,409 ) General and administrative (13,721 ) (12,530 ) (25,873 ) (24,524 ) Casualty-related recoveries/(charges), net (843 ) — (1,839 ) (500 ) Other depreciation and amortization (1,700 ) (1,193 ) (3,323 ) (2,273 ) Income/(loss) from unconsolidated entities (573 ) (428 ) 58,586 (3,993 ) Interest expense (29,673 ) (31,691 ) (58,473 ) (64,575 ) Interest income and other income/(expense), net 382 1,426 742 2,841 Tax benefit/(expense), net 1,404 2,230 1,829 5,559 Gain/(loss) on sale of real estate owned, net of tax 79,042 26,709 79,042 51,003 Net (income)/loss attributable to redeemable noncontrolling interests in the Operating Partnership (3,029 ) (1,077 ) (5,617 ) (1,724 ) Net (income)/loss attributable to noncontrolling interests — (2 ) (7 ) (6 ) Net income/(loss) attributable to UDR, Inc. $ 86,855 $ 30,007 $ 160,677 $ 48,368 (a) Same-Store Community population consisted of 35,250 apartment homes. (b) Same-Store Community population consisted of 35,250 apartment homes.
Details of assets of UDR's reportable segments	The following table details the assets of UDR’s reportable segments as of June 30, 2015 and December 31, 2014 (dollars in thousands) : June 30, December 31, Reportable apartment home segment assets: Same-Store Communities: West Region $ 2,608,586 $ 2,592,156 Mid-Atlantic Region 1,541,420 1,533,993 Southeast Region 738,595 733,068 Northeast Region 1,081,035 1,076,656 Southwest Region 443,526 440,721 Non-Mature Communities/Other 2,012,117 2,006,665 Total assets 8,425,279 8,383,259 Accumulated depreciation (2,557,949 ) (2,434,772 ) Total assets — net book value 5,867,330 5,948,487 Reconciling items: Cash and cash equivalents 2,990 15,224 Restricted cash 22,912 22,340 Deferred financing costs, net 19,930 22,686 Notes receivable, net 15,494 14,369 Investment in and advances to unconsolidated joint ventures, net 914,815 718,226 Other assets 96,259 105,202 Total consolidated assets $ 6,939,730 $ 6,846,534

Reportable Segments (UNITED D55

Reportable Segments (UNITED DOMINION REALTY, L.P.) (Tables)	6 Months Ended
	Jun. 30, 2015
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 six months ended June 30, 2015 and 2014 , and reconciles NOI to Net income/(loss) attributable to OP unitholders in the Consolidated Statements of Operations (dollars in thousands) : Three Months Ended Six Months Ended June 30, (a) June 30, (b) 2015 2014 2015 2014 Reportable apartment home segment rental income Same-Store Communities West Region $ 48,175 $ 44,544 $ 95,082 $ 87,916 Mid-Atlantic Region 17,613 17,364 34,862 34,610 Southeast Region 11,870 11,254 23,549 22,385 Northeast Region 15,497 14,658 30,570 28,925 Southwest Region 6,868 6,653 13,605 13,206 Non-Mature Communities/Other 13,135 10,369 25,585 20,170 Total consolidated rental income $ 113,158 $ 104,842 $ 223,253 $ 207,212 Reportable apartment home segment NOI Same-Store Communities West Region $ 36,447 $ 32,487 $ 71,094 $ 63,958 Mid-Atlantic Region 11,894 11,900 23,360 23,466 Southeast Region 7,938 7,503 15,648 14,959 Northeast Region 12,074 11,415 23,647 22,053 Southwest Region 4,361 4,168 8,574 8,386 Non-Mature Communities/Other 9,569 7,495 18,075 14,563 Total consolidated NOI 82,283 74,968 160,398 147,385 Reconciling items: Property management (3,112 ) (2,883 ) (6,139 ) (5,698 ) Other operating expenses (1,496 ) (1,451 ) (2,986 ) (2,887 ) Real estate depreciation and amortization (44,100 ) (44,697 ) (88,578 ) (88,968 ) General and administrative (7,032 ) (7,459 ) (12,671 ) (14,429 ) Casualty-related recoveries/(charges), net (280 ) — (873 ) (500 ) Interest expense (10,908 ) (10,159 ) (21,679 ) (20,173 ) Gain/(loss) on sale of real estate owned 32,375 16,285 56,998 40,687 Net (income)/loss attributable to noncontrolling interests (347 ) (178 ) (741 ) (458 ) Net income/(loss) attributable to OP unitholders $ 47,383 $ 24,426 $ 83,729 $ 54,959 (a) Same-Store Community population consisted of 18,969 apartment homes. (b) Same-Store Community population consisted of 18,969 apartment homes The following table details the assets of the Operating Partnership’s reportable segments as of June 30, 2015 and December 31, 2014 (dollars in thousands) : June 30, December 31, 2014 Reportable apartment home segment assets Same-Store Communities West Region $ 1,670,364 $ 1,658,042 Mid-Atlantic Region 716,152 713,093 Southeast Region 335,662 333,428 Northeast Region 780,235 777,376 Southwest Region 230,330 228,996 Non-Mature Communities/Other 506,252 527,835 Total assets 4,238,995 4,238,770 Accumulated depreciation (1,474,834 ) (1,403,303 ) Total assets - net book value 2,764,161 2,835,467 Reconciling items: Cash and cash equivalents 164 502 Restricted cash 14,456 13,811 Deferred financing costs, net 3,707 4,475 Other assets 23,090 24,029 Total consolidated assets $ 2,805,578 $ 2,878,284

Consolidation and Basis of Pr56

Consolidation and Basis of Presentation (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Other Interest and Dividend Income	$ 0.3	$ 1.3	$ 0.7	$ 2.5
Deferred Tax Assets, Net	$ 9.1		$ 9.1
Operating Partnership outstanding units	183,278,698		183,278,698
General Partners Capital Account Units Owned Percentage	95.10%		95.10%
Percentage of units outstanding in Heritage OP	4.90%		4.90%
Limited Partners [Member]
Operating Partnership outstanding units	9,062,689		9,062,689
General Partner [Member]
Operating Partnership outstanding units	174,216,009		174,216,009
Non-affiliated Partners [Member]
Percentage of units outstanding in Heritage OP	4.90%		4.90%		5.00%

Consolidation and Basis of Pr57

Consolidation and Basis of Presentation (UNITED DOMINION REALTY, L.P.) (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2015CommunitiesApartment_HomesMarketsshares	Jun. 30, 2014	Jun. 30, 2015CommunitiesApartment_HomesMarketsshares	Jun. 30, 2014	Dec. 31, 2014shares
Entity Information [Line Items]
Number of Real Estate Properties | Communities	136		136
Number of apartments owned (in apartments homes) | Apartment_Homes	39,404		39,404
Operating Partnership outstanding units	183,278,698		183,278,698
Percentage of units outstanding in Heritage OP	4.90%		4.90%
Limited Partners [Member]
Entity Information [Line Items]
Operating Partnership outstanding units	9,062,689		9,062,689
United Dominion Reality L.P. [Member]
Entity Information [Line Items]
Rental revenues percent of General Partner's consolidated rental revenues	53.00%	52.00%	53.00%	52.40%
Number of Real Estate Properties | Communities	67		67
Number of markets operating within (in markets) | Markets	17		17
Number of apartments owned (in apartments homes) | Apartment_Homes	20,569		20,569
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
General Partner [Member]
Entity Information [Line Items]
Operating Partnership outstanding units	174,216,009		174,216,009
Non-affiliated Partners [Member]
Entity Information [Line Items]
OP units outstanding related to limited partner	9,062,689		9,062,689		9,165,473
Percentage of units outstanding in Heritage OP	4.90%		4.90%		5.00%

Significant Accounting Polici58

Significant Accounting Policies (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Accounting Policies [Line Items]
Current Income Tax Expense (Benefit)			$ 0
Deferred Tax Assets, Net	$ 9,100,000		9,100,000
Significant Accounting Policies (Textual) [Abstract]
Notes receivable	15,494,000		15,494,000		$ 14,369,000
Note maturity public capital threshold			5,000,000
Note receivable interest income	300,000	$ 1,300,000	700,000	$ 2,500,000
Net of a valuation allowance	100,000		100,000
Tax benefit/(expense), net	(1,404,000)	(2,190,000)	$ (1,829,000)	(5,519,000)
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			(1,125,000)	38,800,000
Interest Income, Related Party			0	0
Note due February 2017 [Member]
Accounting Policies [Line Items]
Increase (Decrease) in Notes Receivables			$ 1,100,000
Note Receivable Interest Rate	10.00%		10.00%
Significant Accounting Policies (Textual) [Abstract]
Notes receivable					11,869,000
Note maturity public capital threshold			$ 5,000,000
Aggregate Commitment on Note Receivable	$ 12,994,000		$ 12,994,000
Other [Member]
Accounting Policies [Line Items]
Note Receivable Interest Rate	8.00%		8.00%
Significant Accounting Policies (Textual) [Abstract]
Notes receivable	$ 2,500,000		$ 2,500,000		$ 2,500,000
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	$ 224,000	$ 50,000	$ (1,000)	$ 106,000

Real Estate Owned (Details)

Real Estate Owned (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Summary of carrying amounts for real estate owned (at cost)
Land	$ 1,919,597	$ 1,980,221
Depreciable property - held and used:
Building, Improvements, and Furniture, Fixtures and Equipment	6,413,037	6,225,406
Under development:
Real estate under development (net of accumulated depreciation of $0)	92,645	177,632
Real estate owned	8,425,279	8,383,259
Real Estates Owned Accumulated Depreciation	2,557,949	2,434,772
Real Estate Investments, Net	5,867,330	5,948,487
Land [Member]
Under development:
Real estate under development (net of accumulated depreciation of $0)	78,085	24,584
Construction in progress [Member]
Under development:
Real estate under development (net of accumulated depreciation of $0)	$ 14,560	$ 153,048

Real Estate Owned (Details Text

Real Estate Owned (Details Textual) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015USD ($)ft²CommunitiesApartment_HomesStates$ / shares	Jun. 30, 2014USD ($)	Jun. 30, 2015USD ($)ft²CommunitiesApartment_HomesStates$ / shares	Jun. 30, 2014USD ($)	Jun. 30, 2013USD ($)
Real Estate Properties [Line Items]
Communities Held For Sale		1		1
Real Estate Owned (Textual) [Abstract]
Number of states in which there are owned and consolidated communities	10		10
Number of apartment homes owned and consolidated by the Company | Apartment_Homes	39,404		39,404
Number of Real Estate Properties | Communities	136		136
Development costs excluding direct costs and capitlized interest	$ 1,600	$ 2,100	$ 3,800	$ 5,500
Interest capitalized during period	3,800	4,900	8,600	10,200
Other Cost and Expense, Operating	1,769	2,162	3,535	4,088
Proceeds from Sale of Property, Plant, and Equipment			109,900
Payments for (Proceeds from) Investments			90,543	47,922
Gains/(loss) on sales of real estate, net of tax	79,042	26,709	79,042	51,003
Acquisition of real estate			24,067	0
Casualty-related (recoveries)/charges, net	(843)	0	(1,839)	(500)
Casualty (Recoveries)/Charges	$ (843)	0	$ (1,839)	(500)
Communities Sold | Communities			3
Apartment Homes Sold | Apartment_Homes			812
Home Acquisition [Member]
Real Estate Owned (Textual) [Abstract]
Number of Properties Purchased	6
Fair Value of Assets Acquired	$ 908,000
Business Acquisition, Share Price | $ / shares	$ 35		$ 35
Acquisition of real estate	$ 90,000
Cash Acquired from Acquisition	$ 65,000
Unconsolidated Joint Venture Four Texas [Member]
Real Estate Owned (Textual) [Abstract]
Proceeds from Sale of Property, Plant, and Equipment			$ 43,500
Gain (Loss) on Disposition of Property Plant Equipment			$ 59,100
1745 Shea [Member]
Real Estate Owned (Textual) [Abstract]
Square Footage | ft²	120,000		120,000
UDR, Inc. [Member]
Real Estate Owned (Textual) [Abstract]
Square Footage | ft²	44,000		44,000
United Dominion Reality L.P. [Member]
Real Estate Owned (Textual) [Abstract]
Number of states in which there are owned and consolidated communities | States	9		9
Number of apartment homes owned and consolidated by the Company | Apartment_Homes	20,569		20,569
Number of Real Estate Properties | Communities	67		67
Development costs excluding direct costs and capitlized interest	$ 195	542	$ 328	1,300
Interest capitalized during period	0	1,000	100	2,000
Other Cost and Expense, Operating	1,496	1,451	2,986	2,887
Proceeds from Sale of Property, Plant, and Equipment			45,300
Payments for (Proceeds from) Investments			27,700
Gains/(loss) on sales of real estate, net of tax	32,375	16,285	56,998	40,687
Casualty-related (recoveries)/charges, net	280	0	873		$ 500
Casualty (Recoveries)/Charges	$ (280)	0	$ (873)	(500)
Communities Sold | Communities			1
Apartment Homes Sold | Apartment_Homes			240
Operating Community [Member]
Real Estate Owned (Textual) [Abstract]
Gain (Loss) on Disposition of Property Plant Equipment		$ 26,700		49,900
Operating Community [Member] | Unconsolidated Joint Venture Vitruvian Park [Member]
Real Estate Owned (Textual) [Abstract]
Number of Real Estate Properties	3		3
Operating Community [Member] | Unconsolidated Joint Venture Four Texas [Member]
Real Estate Owned (Textual) [Abstract]
Number of Real Estate Properties | Communities	8		8
Development Community [Member] | Unconsolidated Joint Venture Four Texas [Member]
Real Estate Owned (Textual) [Abstract]
Number of Real Estate Properties	0		0
Land [Member]
Real Estate Owned (Textual) [Abstract]
Gain (Loss) on Disposition of Property Plant Equipment				$ 1,100
Office Building [Member] | 1745 Shea [Member]
Real Estate Owned (Textual) [Abstract]
Property, Plant and Equipment, Additions			$ 24,000
UDR DownREIT Unit [Member] | Home Acquisition [Member]
Real Estate Owned (Textual) [Abstract]
Stock Issued During Period, Value, Acquisitions	$ 753,000

Real Estate Owned (UNITED DOM61

Real Estate Owned (UNITED DOMINION REALTY, L.P.) (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Summary of carrying amounts for real estate owned (at cost)
Land	$ 1,919,597	$ 1,980,221
Under development:
Real estate under development (net of accumulated depreciation of $0 and $0, respectively)	92,645	177,632
Real estate owned	8,425,279	8,383,259
Less: accumulated depreciation	(2,557,949)	(2,434,772)
Real estate owned, net	5,867,330	5,948,487
Land [Member]
Under development:
Real estate under development (net of accumulated depreciation of $0 and $0, respectively)	78,085	24,584
Construction in progress [Member]
Under development:
Real estate under development (net of accumulated depreciation of $0 and $0, respectively)	14,560	153,048
United Dominion Reality L.P. [Member]
Summary of carrying amounts for real estate owned (at cost)
Land	1,006,651	1,008,014
Depreciable property - held and used:
Building, improvements, and furniture, fixture and equipment	3,232,344	3,230,756
Under development:
Real estate owned	4,238,995	4,238,770
Less: accumulated depreciation	(1,474,834)	(1,403,303)
Real estate owned, net	$ 2,764,161	$ 2,835,467

Real Estate Owned (UNITED DOM62

Real Estate Owned (UNITED DOMINION REALTY, L.P.) (Details Textual) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015USD ($)CommunitiesApartment_HomesStates$ / shares	Jun. 30, 2014USD ($)	Jun. 30, 2015USD ($)CommunitiesApartment_HomesStates$ / shares	Jun. 30, 2014USD ($)	Jun. 30, 2013USD ($)	Dec. 31, 2014USD ($)
Real Estate Owned (Textual) [Abstract]
Number of communities owned (in communities) | Communities	136		136
Number of states operating within (in states)	10		10
Number of apartments owned (in apartments homes) | Apartment_Homes	39,404		39,404
Number of communities acquired apartment homes are within | Communities	0
Development costs excluding direct costs and capitlized interest	$ 1,600	$ 2,100	$ 3,800	$ 5,500
Interest capitalized during period	3,800	4,900	8,600	10,200
Other Cost and Expense, Operating	1,769	2,162	3,535	4,088
Proceeds from Sale of Property, Plant, and Equipment			109,900
Gains/(loss) on sales of real estate, net of tax	79,042	26,709	79,042	51,003
Deferred profit from the sale of properties	6,800		6,800			$ 28,500
Casualty-related (recoveries)/charges, net	(843)	0	(1,839)	(500)
Casualty (Recoveries)/Charges	$ (843)	0	(1,839)	(500)
Payments for (Proceeds from) Investments			90,543	47,922
Acquisition of real estate			$ 24,067	0
Communities Sold | Communities			3
Apartment Homes Sold | Apartment_Homes			812
United Dominion Reality L.P. [Member]
Real Estate Owned (Textual) [Abstract]
Number of communities owned (in communities) | Communities	67		67
Number of states operating within (in states) | States	9		9
Number of apartments owned (in apartments homes) | Apartment_Homes	20,569		20,569
Development costs excluding direct costs and capitlized interest	$ 195	542	$ 328	1,300
Interest capitalized during period	0	1,000	100	2,000
Other Cost and Expense, Operating	1,496	1,451	2,986	2,887
Proceeds from Sale of Property, Plant, and Equipment			45,300
Gains/(loss) on sales of real estate, net of tax	32,375	16,285	56,998	40,687
Deferred profit from the sale of properties	0		0			$ 24,622
Casualty-related (recoveries)/charges, net	280	0	873		$ 500
Casualty (Recoveries)/Charges	(280)	$ 0	(873)	$ (500)
Payments for (Proceeds from) Investments			$ 27,700
Communities Sold | Communities			1
Apartment Homes Sold | Apartment_Homes			240
Home Acquisition [Member]
Real Estate Owned (Textual) [Abstract]
Fair Value of Assets Acquired	$ 908,000
Business Acquisition, Share Price | $ / shares	$ 35		$ 35
Acquisition of real estate	$ 90,000
Cash Acquired from Acquisition	$ 65,000
Number of Properties Purchased	6
UDR DownREIT Unit [Member] | Home Acquisition [Member]
Real Estate Owned (Textual) [Abstract]
Stock Issued During Period, Value, Acquisitions	$ 753,000

Discontinued Operations (Detail

Discontinued Operations (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015USD ($)	Jun. 30, 2014USD ($)	Jun. 30, 2015USD ($)	Jun. 30, 2014USD ($)
Discontinued Operation, Tax Effect of Discontinued Operation	$ 0	$ (40)	$ 0	$ (40)
Disposal Group, Including Discontinued Operation, Interest Expense	0	2	0	3
Disposal Group, Including Discontinued Operation, Operating Income (Loss)	0	$ 9	0	$ 18
Discontinued Operations (Textual) [Abstract]
Communities held for sale (in communities)		1		1
Summary of income from discontinued operations
Rental expenses	0	$ 78	0	$ 126
Real estate depreciation	0	89	0	214
Income/(loss) from discontinued operations, net of tax	0	18	0	(69)
Income/(loss) from discontinued operations attributable to common stockholders	$ 0	17	$ 0	(67)
Operating Community [Member]
Gain (Loss) on Disposition of Property Plant Equipment		$ 26,700		49,900
Land [Member]
Gain (Loss) on Disposition of Property Plant Equipment				$ 1,100

Joint Ventures (Details)

Joint Ventures (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2015USD ($)Communities	Jun. 30, 2014USD ($)	Jun. 30, 2015USD ($)Communities	Jun. 30, 2014USD ($)	Jun. 30, 2013USD ($)	Dec. 31, 2014USD ($)
Financial information relating to unconsolidated joint ventures operations
UDR income/(loss) from unconsolidated entities	$ (573,000)	$ (428,000)	$ 58,586,000	$ (3,993,000)
Combined summary of balance sheets relating to unconsolidated joint ventures
Investment in and advances to unconsolidated joint ventures, net	914,815,000		914,815,000			$ 718,226,000
Deferred gains on the sale of depreciable property	$ 6,800,000		$ 6,800,000			28,500,000
Number of Real Estate Properties | Communities	136		136
Unconsolidated Joint Ventures [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment Summarized Financial Information Income/(loss) from discontinued operations	$ 0	(4,705,000)	$ 182,488,000	(31,688,000)
Financial information relating to unconsolidated joint ventures operations
Total revenues	55,450,000	48,379,000	109,996,000		$ 87,334,000
Equity Method Investment Summarized Financial Information Property Operating Expense	(21,557,000)	(18,001,000)	(41,724,000)	(32,360,000)
Real estate depreciation and amortization	(19,402,000)	(16,808,000)	(38,754,000)		(31,496,000)
Net income /(loss)	(1,685,000)	(6,063,000)	179,769,000		$ (35,289,000)
Combined summary of balance sheets relating to unconsolidated joint ventures
Total real estate, net	3,004,723,000		3,004,723,000			2,941,803,000
Equity Method of Investment Summarized Financial Information, Assets Sold or Held For Sale	0		0			216,196,000
Equity Method Investment Summarized Financial Information Cash and cash equivalents	36,820,000		36,820,000			32,544,000
Equity Method Investment Summarized Financial Information Other assets	32,869,000		32,869,000			28,707,000
Total assets	3,074,412,000		3,074,412,000			3,219,250,000
Amount due to UDR	6,434,000		6,434,000			2,997,000
Third party debt	1,529,724,000		1,529,724,000			1,504,477,000
Equity Method of Investment Summarized Financial Information, Liabilities Sold or Held For Sale	0		0			229,706,000
Equity Method Investment Summarized Financial Information Accounts payable and accrued liabilities	63,521,000		63,521,000			44,335,000
Total liabilities	1,599,679,000		1,599,679,000			1,781,515,000
Total equity	1,474,733,000		1,474,733,000			1,437,735,000
Equity Method Investment, Summarized Financial Information, Liabilities and Equity	3,074,412,000		3,074,412,000			3,219,250,000
Investment in and advances to unconsolidated joint ventures, net	695,980,000		695,980,000			655,519,000
Equity Method of Investment Summarized Financial Information Operating income/(loss)	14,491,000	13,570,000	29,518,000	23,478,000
Equity Method Investment Summarized Financial Information Interest expense	(16,169,000)	(14,928,000)	(32,230,000)	(27,079,000)
Equity Method Investment Summarized Financial Information Other income/(expense)	(7,000)	0	(7,000)	0
Unconsolidated Joint Venture Four Texas [Member]
Combined summary of balance sheets relating to unconsolidated joint ventures
Deferred gains on the sale of depreciable property	24,200,000		24,200,000
Operating Community [Member] | Unconsolidated Joint Venture UDR Met Life I Partnership [Member]
Combined summary of balance sheets relating to unconsolidated joint ventures
Investment in and advances to unconsolidated joint ventures, net	$ 14,181,000		$ 14,181,000			$ 13,306,000
Equity Method Investment, Ownership Percentage	16.10%		16.10%			15.70%
Number of apartment homes	0		0
Number of Real Estate Properties	4		4
Operating Community [Member] | Unconsolidated Joint Venture UDR MetLife II Partnership [Member]
Combined summary of balance sheets relating to unconsolidated joint ventures
Investment in and advances to unconsolidated joint ventures, net	$ 428,321,000		$ 428,321,000			$ 431,277,000
Equity Method Investment, Ownership Percentage	50.00%		50.00%			50.00%
Number of apartment homes	4,642		4,642
Number of Real Estate Properties	21		21
Operating Community [Member] | Unconsolidated Joint Venture Vitruvian Park [Member]
Combined summary of balance sheets relating to unconsolidated joint ventures
Investment in and advances to unconsolidated joint ventures, net	$ 75,531,000		$ 75,531,000			$ 80,302,000
Equity Method Investment, Ownership Percentage	50.00%		50.00%			50.00%
Number of apartment homes	1,130		1,130
Number of Real Estate Properties	3		3
Operating Community [Member] | Unconsolidated Joint Venture Three [Member]
Combined summary of balance sheets relating to unconsolidated joint ventures
Investment in and advances to unconsolidated joint ventures, net	$ 19,775,000		$ 19,775,000			$ 21,596,000
Equity Method Investment, Ownership Percentage	30.00%		30.00%			30.00%
Number of apartment homes	660		660
Number of Real Estate Properties	3		3
Operating Community [Member] | Unconsolidated Joint Venture Four Texas [Member]
Combined summary of balance sheets relating to unconsolidated joint ventures
Equity Method Investment, Ownership Percentage	0.00%		0.00%			20.00%
Number of Real Estate Properties | Communities	8		8
Operating Community [Member] | Unconsolidated Joint Venture Other MetLife [Member]
Combined summary of balance sheets relating to unconsolidated joint ventures
Investment in and advances to unconsolidated joint ventures, net	$ 158,172,000		$ 158,172,000			$ 134,939,000
Equity Method Investment, Ownership Percentage	50.60%		50.60%			50.60%
Number of apartment homes	1,437		1,437
Number of Real Estate Properties	1		1
Land Parcel [Member] | Unconsolidated Joint Venture Vitruvian Park [Member]
Combined summary of balance sheets relating to unconsolidated joint ventures
Number of Real Estate Properties	6		6
Development Community [Member] | Unconsolidated Joint Venture Four Texas [Member]
Combined summary of balance sheets relating to unconsolidated joint ventures
Investment in and advances to unconsolidated joint ventures, net	$ 0		$ 0			$ (25,901,000)
Number of apartment homes	0		0
Number of Real Estate Properties	0		0
Development Community [Member] | Unconsolidated Joint Venture Other MetLife [Member]
Combined summary of balance sheets relating to unconsolidated joint ventures
Number of Real Estate Properties	4		4
Development Community [Member] | Participating Loan Investment Steele Creek Denver Colorado [Member]
Combined summary of balance sheets relating to unconsolidated joint ventures
Investment in and advances to unconsolidated joint ventures, net	$ 85,208,000		$ 85,208,000			62,707,000
Income from Participating Loan	$ 1,352,000	456,000	$ 2,506,000	777,000
Participating Loan, Interest Rate, Stated Percentage	6.50%		6.50%
Participating Loan Years to Maturity			2 years 1 month 6 days
Development Community [Member] | Preferred Equity Investment West Coast Development JV [Member]
Combined summary of balance sheets relating to unconsolidated joint ventures
Investment in and advances to unconsolidated joint ventures, net	$ 133,627,000		$ 133,627,000			$ 0
Income from Participating Loan	$ (548)	$ 0	$ (548)	$ 0
Participating Loan, Interest Rate, Stated Percentage	6.50%		6.50%
Land [Member] | Unconsolidated Joint Venture Other MetLife [Member]
Combined summary of balance sheets relating to unconsolidated joint ventures
Number of Real Estate Properties	1		1

Joint Ventures (Details Textual

Joint Ventures (Details Textual) - Debt Instrument, Name [Domain] $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015USD ($)Communities	Jun. 30, 2014USD ($)	Jun. 30, 2015USD ($)Communities	Jun. 30, 2014USD ($)	Dec. 31, 2014USD ($)
Schedule of Equity Method Investments [Line Items]
Proceeds from Sale of Property, Plant, and Equipment			$ 109,900
Number of Real Estate Properties | Communities	136		136
Community Threshold, Period Above Occupancy Threshold			3 months
Secured Debt	$ 1,350,439		$ 1,350,439		$ 1,361,529
Joint Ventures
Real Estate Owned Gross	8,425,279		8,425,279		8,383,259
Unamortized discount	5,700		5,700		6,700
First installment of payable incurred in partial consideration for acquisition of ownership interest in joint venture	191,442		191,442
Second installment of payable incurred in partial consideration for acquisition of ownership interest in joint venture	242,692		242,692
Interest expense	(29,673)	$ (31,691)	(58,473)	$ (64,575)
Company's equity investment in joint venture	914,815		914,815		718,226
Deferred profit from the sale of properties	6,800		6,800		$ 28,500
Management fees for our involvement in the joint ventures	2,600	2,300	5,200	5,600
Unconsolidated Joint Venture Four Texas [Member]
Schedule of Equity Method Investments [Line Items]
Proceeds from Sale of Property, Plant, and Equipment			43,500
Joint Ventures
Deferred profit from the sale of properties	24,200		24,200
Fee Income from the Sale of Real Estate			9,600
Gain (Loss) on Disposition of Property Plant Equipment			59,100
Unconsolidated Joint Venture 399 Fremont [Member]
Schedule of Equity Method Investments [Line Items]
Number of apartments of development community					0
Unconsolidated Joint Venture Wolff [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment Cost of Ownership Interest, Funded	129,600		129,600
Equity Method Investment Cost of Ownership Interest, Remaining Commitment	$ 6,700		6,700
Total Fixed Price Option Sales Price			$ 597,000
Number of Markets Operating Within	3		3
Preferred Return Interest Rate			650.00%
Community Threshold, Percent Occupancy Threshold			8000.00%
Community Threshold, Period Above Occupancy Threshold			90 days
Fixed Price Option Period			1 year
Joint Ventures
Equity Method Investment Cost of Ownership Interest	$ 136,000		$ 136,000
Equity Method Investment, Ownership Percentage	4800.00%		4800.00%
Land [Member]
Joint Ventures
Gain (Loss) on Disposition of Property Plant Equipment				1,100
Land [Member] | Unconsolidated Joint Venture Other MetLife [Member]
Schedule of Equity Method Investments [Line Items]
Number of Real Estate Properties	1		1
Operating Community [Member]
Joint Ventures
Gain (Loss) on Disposition of Property Plant Equipment		$ 26,700		$ 49,900
Operating Community [Member] | Unconsolidated Joint Venture Vitruvian Park [Member]
Schedule of Equity Method Investments [Line Items]
Number of Real Estate Properties	3		3
Number of apartment homes	1,130		1,130
Joint Ventures
Company's equity investment in joint venture	$ 75,531		$ 75,531		$ 80,302
Equity Method Investment, Ownership Percentage	50.00%		50.00%		50.00%
Operating Community [Member] | Unconsolidated Joint Venture UDR Met Life I Partnership [Member]
Schedule of Equity Method Investments [Line Items]
Number of Real Estate Properties	4		4
Number of apartment homes	0		0
Joint Ventures
Company's equity investment in joint venture	$ 14,181		$ 14,181		$ 13,306
Equity Method Investment, Ownership Percentage	16.10%		16.10%		15.70%
Operating Community [Member] | Unconsolidated Joint Venture UDR MetLife II Partnership [Member]
Schedule of Equity Method Investments [Line Items]
Number of Real Estate Properties	21		21
Number of apartment homes	4,642		4,642
Joint Ventures
Company's equity investment in joint venture	$ 428,321		$ 428,321		$ 431,277
Equity Method Investment, Ownership Percentage	50.00%		50.00%		50.00%
Operating Community [Member] | Unconsolidated Joint Venture Three Washington DC [Member]
Schedule of Equity Method Investments [Line Items]
Number of Real Estate Properties	3		3
Number of apartment homes	660		660
Joint Ventures
Company's equity investment in joint venture	$ 19,775		$ 19,775		$ 21,596
Equity Method Investment, Ownership Percentage	30.00%		30.00%		30.00%
Operating Community [Member] | Unconsolidated Joint Venture Four Texas [Member]
Schedule of Equity Method Investments [Line Items]
Number of Real Estate Properties | Communities	8		8
Joint Ventures
Equity Method Investment, Ownership Percentage	0.00%		0.00%		20.00%
Operating Community [Member] | Unconsolidated Joint Venture Other MetLife [Member]
Schedule of Equity Method Investments [Line Items]
Number of Real Estate Properties	1		1
Number of apartment homes	1,437		1,437
Joint Ventures
Company's equity investment in joint venture	$ 158,172		$ 158,172		$ 134,939
Equity Method Investment, Ownership Percentage	50.60%		50.60%		50.60%
Operating Community [Member] | Unconsolidated Joint Venture Wolff [Member]
Schedule of Equity Method Investments [Line Items]
Number of Real Estate Properties	2		2
Number of apartment homes	1,533		1,533
Development Community [Member] | Unconsolidated Joint Venture Four Texas [Member]
Schedule of Equity Method Investments [Line Items]
Number of Real Estate Properties	0		0
Number of apartment homes	0		0
Joint Ventures
Company's equity investment in joint venture	$ 0		$ 0		$ (25,901)
Development Community [Member] | Unconsolidated Joint Venture Other MetLife [Member]
Schedule of Equity Method Investments [Line Items]
Number of Real Estate Properties	4		4
Development Community [Member] | Unconsolidated Joint Venture Wolff [Member]
Schedule of Equity Method Investments [Line Items]
Number of Real Estate Properties	5		5
Development Community [Member] | Preferred Equity Investment West Coast Development JV [Member]
Joint Ventures
Company's equity investment in joint venture	$ 133,627		$ 133,627		$ 0
Equity Method Investment, Preferred Return			1,000
Equity Method Investment, Transaction Expenses			$ 1,500

Secured and Unsecured Debt (Det

Secured and Unsecured Debt (Details) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2015USD ($)	Jun. 30, 2015USD ($)	Dec. 31, 2014USD ($)
Secured debt instruments
Weighted average interest rate	3.58%
Long-term Debt	$ 3,564,403	$ 3,564,403	$ 3,583,105
Unsecured Debt	2,213,964	$ 2,213,964	2,221,576
Weighted Average Years to Maturity		4 years 29 days
Line of Credit Facility, Amount Outstanding	2,300	$ 2,300	1,900
Fixed Rate Debt [Member]
Secured debt instruments
Principal outstanding	$ 975,024	$ 975,024	969,296
Weighted average interest rate	5.28%
Weighted Average Years to Maturity		2 years 6 months 10 days
Number of Communities Encumbered	28
Variable Rate Debt [Member]
Secured debt instruments
Principal outstanding	$ 375,415	$ 375,415	392,233
Weighted average interest rate	1.45%
Weighted Average Years to Maturity		5 years 3 months
Number of Communities Encumbered	10
Mortgages Notes Payable [Member] | Fixed Rate Debt [Member]
Secured debt instruments
Weighted average interest rate	5.50%
Weighted Average Years to Maturity		1 year 20 days
Number of Communities Encumbered	7
Mortgages Notes Payable [Member] | Variable Rate Debt [Member]
Secured debt instruments
Weighted average interest rate	1.94%
Weighted Average Years to Maturity		1 year 6 months 25 days
Number of Communities Encumbered	1
Tax-exempt secured notes payable [Member] | Variable Rate Debt [Member]
Secured debt instruments
Weighted average interest rate	0.84%
Weighted Average Years to Maturity		7 years 8 months 8 days
Number of Communities Encumbered	2
Fannie Mae credit facilities [Member] | Fixed Rate Debt [Member]
Secured debt instruments
Debt, Weighted Average Interest Rate	5.12%	5.12%
Weighted Average Years to Maturity		3 years 6 months 14 days
Number of Communities Encumbered	21
Fannie Mae credit facilities [Member] | Variable Rate Debt [Member]
Secured debt instruments
Debt Instrument, Interest Rate at Period End	1.63%	1.63%
Weighted Average Years to Maturity		4 years 9 months 10 days
Number of Communities Encumbered	7
Secured Debt [Member]
Secured debt instruments
Principal outstanding	$ 1,350,439	$ 1,350,439	1,361,529
Weighted average interest rate	4.22%
Long-term Debt	$ 1,350,439	$ 1,350,439
Weighted Average Years to Maturity		3 years 3 months 18 days
Number of Communities Encumbered	38
Secured Debt [Member] | Fixed Rate Debt [Member]
Secured debt instruments
Long-term Debt	$ 975,024	$ 975,024
Secured Debt [Member] | Variable Rate Debt [Member]
Secured debt instruments
Long-term Debt	$ 375,415	$ 375,415
Unsecured Revolving Credit Facility due October 2015 [Member]
Secured debt instruments
Weighted average interest rate	1.12%
Weighted Average Years to Maturity		2 years 5 months 4 days
Line of Credit Facility, Amount Outstanding	$ 457,000	$ 457,000	152,500
ThreePointSevenTermNotesDueOctober2020 [Member]
Secured debt instruments
Weighted average interest rate		3.70%
Senior Notes	$ 299,958	$ 299,958	299,954
Weighted Average Years to Maturity		5 years 3 months
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	$ 397,656	$ 397,656	397,477
Weighted Average Years to Maturity		6 years 6 months 10 days
3.75 MTN Due July 2024 [Member]
Secured debt instruments
Weighted average interest rate	3.75%
Senior Notes	$ 299,062	$ 299,062	299,010
Weighted Average Years to Maturity		9 years
1.67% Term Notes due December 2016 [Member]
Secured debt instruments
Weighted average interest rate		1.33%
Senior Notes	35,000	$ 35,000	35,000
Weighted Average Years to Maturity		2 years 11 months 1 day
2.68% Term Notes due December 2016 [Member]
Secured debt instruments
Weighted average interest rate		1.53%
Senior Notes	100,000	$ 100,000	100,000
Weighted Average Years to Maturity		2 years 11 months 4 days
Five Point Two Five Percent, Medium Term Notes, Due January 2015 [Member]
Secured debt instruments
Weighted average interest rate		0.00%
Senior Notes	0	$ 0	325,169
Weighted Average Years to Maturity
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		6 months 14 days
6.21 Medium Term Note, Due January 2016 [Member]
Secured debt instruments
Weighted average interest rate		6.21%
Senior Notes	12,609	$ 12,609	0
Weighted Average Years to Maturity		1 year 3 days
2.90% Term Notes due January 2016 [Member]
Secured debt instruments
Weighted average interest rate		1.70%
Senior Notes	$ 215,000	$ 215,000	215,000
Weighted Average Years to Maturity		2 years 11 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 2 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	298,749	$ 298,749	298,535
Weighted Average Years to Maturity		2 years 11 months 1 day
Other [Member]
Secured debt instruments
Senior Notes	$ 26	$ 26	27
Unsecured Debt [Member]
Secured debt instruments
Weighted average interest rate	3.20%
Long-term Debt	$ 2,213,964	2,213,964
Unsecured Debt	2,213,964	$ 2,213,964	2,221,576
Weighted Average Years to Maturity		4 years 6 months 21 days
Fair Value, Measurements, Recurring [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member] | Mortgages Notes Payable [Member] | Mortgages Notes Payable [Member] | Fixed Rate Debt [Member]
Secured debt instruments
Principal outstanding	408,736	$ 408,736	401,210
Fair Value, Measurements, Recurring [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member] | Mortgages Notes Payable [Member] | Mortgages Notes Payable [Member] | Variable Rate Debt [Member]
Secured debt instruments
Principal outstanding	31,337	31,337	31,337
Fair Value, Measurements, Recurring [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member] | Fannie Mae credit facilities [Member] | Fannie Mae credit facilities [Member] | Fixed Rate Debt [Member]
Secured debt instruments
Principal outstanding	566,288	566,288	568,086
Fair Value, Measurements, Recurring [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member] | Fannie Mae credit facilities [Member] | Fannie Mae credit facilities [Member] | Variable Rate Debt [Member]
Secured debt instruments
Principal outstanding	$ 249,378	$ 249,378	$ 266,196

Secured and Unsecured Debt (D67

Secured and Unsecured Debt (Details 1) - Line of Credit Facility, Lender [Domain] - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2013	Dec. 31, 2014
Line of Credit Facility [Line Items]
Unamortized discount	$ 5,700		$ 6,700
Secured credit facilities
Borrowings outstanding	2,300		1,900
Five Point Two Five Percent, Medium Term Notes, Due January 2015 [Member]
Line of Credit Facility [Line Items]
Unamortized discount	0		6
Fannie Mae [Member]
Secured credit facilities
Borrowings outstanding	815,666		$ 834,282
Weighted average daily borrowings during the period ended	830,434	$ 835,873
Maximum daily borrowings during the period ended	$ 834,003	$ 837,564
Weighted average interest rate during the period ended	4.01%	4.10%
Interest rate at the end of the period	4.05%		4.00%
Four Point Two Five Percentage Medium-Term Notes due June 2018 [Member]
Line of Credit Facility [Line Items]
Unamortized discount	$ 1,251		$ 1,465
Three point seven percent medium term note due October 2020 [Member]
Line of Credit Facility [Line Items]
Unamortized discount	42		46
Four Point Six Three Percent Term Medium Notes Due January Two Thousand Twenty-Two [Member]
Line of Credit Facility [Line Items]
Unamortized discount	2,344		2,523
3.75 MTN Due July 2024 [Member]
Line of Credit Facility [Line Items]
Unamortized discount	$ 938		$ 990

Secured and Unsecured Debt (D68

Secured and Unsecured Debt (Details 2) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Secured Debt, Encumbers Real Estate Owned, Amount	$ 2,200,000
Secured Debt, Encumbers Real Estate Owned, Percent	26.60%
Debt Instrument Weighted Average Years to Maturity	4 years 29 days
Unamortized discount	$ 5,700	$ 6,700
Aggregate maturities of secured debt
2,014	191,442
2,015	242,692
2,016	731,219
2,017	858,099
2,018	313,571
Thereafter	1,227,380
Total	1,350,439	1,361,529
Secured Debt, Unencumbered Real Estate Owned, Amount	$ 6,200,000
Secured Debt, Unencumbered Real Estate Owned, Percent	73.40%
Fixed Rate Debt [Member]
Debt Instrument [Line Items]
Debt Instrument Weighted Average Years to Maturity	2 years 6 months 10 days
Variable Rate Debt [Member]
Debt Instrument [Line Items]
Debt Instrument Weighted Average Years to Maturity	5 years 3 months
ThreePointSevenTermNotesDueOctober2020 [Member]
Debt Instrument [Line Items]
Debt Instrument Weighted Average Years to Maturity	5 years 3 months
2.68% Term Notes due December 2016 [Member]
Debt Instrument [Line Items]
Debt Instrument Weighted Average Years to Maturity	2 years 11 months 4 days
Four Point Six Three Percent Term Medium Notes Due January Two Thousand Twenty-Two [Member]
Debt Instrument [Line Items]
Debt Instrument Weighted Average Years to Maturity	6 years 6 months 10 days
Unamortized discount	$ 2,344	2,523
Mortgages Notes Payable [Member] | Fixed Rate Debt [Member]
Debt Instrument [Line Items]
Debt Instrument Weighted Average Years to Maturity	1 year 20 days
Mortgages Notes Payable [Member] | Variable Rate Debt [Member]
Debt Instrument [Line Items]
Debt Instrument Weighted Average Years to Maturity	1 year 6 months 25 days
Tax Exempt Notes Payable [Member] | Variable Rate Debt [Member]
Debt Instrument [Line Items]
Debt Instrument Weighted Average Years to Maturity	7 years 8 months 8 days
Fannie Mae credit facilities [Member] | Fixed Rate Debt [Member]
Debt Instrument [Line Items]
Debt Instrument Weighted Average Years to Maturity	3 years 6 months 14 days
Fannie Mae credit facilities [Member] | Variable Rate Debt [Member]
Debt Instrument [Line Items]
Debt Instrument Weighted Average Years to Maturity	4 years 9 months 10 days
3.75 MTN Due July 2024 [Member]
Debt Instrument [Line Items]
Debt Instrument Weighted Average Years to Maturity	9 years
Unamortized discount	$ 938	990
Five Point Two Five Percent, Medium Term Notes, Due January 2015 [Member]
Debt Instrument [Line Items]
Debt Instrument Weighted Average Years to Maturity
Unamortized discount	$ 0	$ 6

Secured and Unsecured Debt (D69

Secured and Unsecured Debt (Details 3) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Summary of unsecured debt
Unsecured Debt, Total	$ 2,213,964	$ 2,221,576
Unamortized discount	5,700	6,700
4.63% Medium-Term Notes due January 2022 [Member]
Summary of unsecured debt
Senior Unsecured Notes	397,656	397,477
Unamortized discount	2,344	2,523
1.67% Term Notes due December 2016 [Member]
Summary of unsecured debt
Senior Unsecured Notes	35,000	35,000
2.68% Term Notes due December 2016 [Member]
Summary of unsecured debt
Senior Unsecured Notes	100,000	100,000
5.25% Medium-Term Notes due January 2015 [Member]
Summary of unsecured debt
Senior Unsecured Notes	0	325,169
Unamortized discount	0	6
5.25% Medium-Term Notes due January 2016 [Member]
Summary of unsecured debt
Senior Unsecured Notes	83,260	83,260
2.90% Term Notes due January 2016 [Member]
Summary of unsecured debt
Senior Unsecured Notes	215,000	215,000
8.50% Debentures due September 2024 [Member]
Summary of unsecured debt
Senior Unsecured Notes	15,644	15,644
4.25% Medium-Term Notes due June 2018 [Member]
Summary of unsecured debt
Senior Unsecured Notes	298,749	298,535
Unamortized discount	1,251	1,465
Other [Member]
Summary of unsecured debt
Senior Unsecured Notes	$ 26	$ 27

Secured and Unsecured Debt (D70

Secured and Unsecured Debt (Details 4) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Summary of short-term bank borrowings under unsecured commercial bank credit facility
Borrowings outstanding at end of period	$ 2,300
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
Weighted average daily borrowings during the period ended	402,514	$ 291,761
Maximum daily borrowings during the period ended	$ 539,100	$ 625,000
Weighted average interest rate during the period ended	1.20%	1.20%
Interest rate at the end of the period	1.10%		1.10%
Unsecured Revolving Credit Facility due October 2015 [Member]
Summary of short-term bank borrowings under unsecured commercial bank credit facility
Borrowings outstanding at end of period	$ 457,000

Secured and Unsecured Debt (D71

Secured and Unsecured Debt (Details 5) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Aggregate maturities of unsecured debt
2,014	$ 191,442
2,015	242,692
2,016	731,219
2,017	858,099
2,018	313,571
Thereafter	1,227,380
Unsecured Debt, Total	2,213,964	$ 2,221,576
Long-term Debt	3,564,403	3,583,105
Secured Debt [Member]
Aggregate maturities of unsecured debt
2,014	191,363
2,015	148,223
2,016	274,219
2,017	209,654
2,018	313,571
Thereafter	213,409
Long-term Debt	1,350,439
Unsecured Debt [Member]
Aggregate maturities of unsecured debt
2,014	79
2,015	94,469
2,016	457,000
2,017	648,445
2,018	0
Thereafter	1,013,971
Unsecured Debt, Total	2,213,964	$ 2,221,576
Long-term Debt	2,213,964
Fixed Rate Debt [Member] | Secured Debt [Member]
Aggregate maturities of unsecured debt
2,014	191,363
2,015	148,223
2,016	177,882
2,017	121,685
2,018	245,871
Thereafter	90,000
Long-term Debt	975,024
Variable Rate Debt [Member] | Secured Debt [Member]
Aggregate maturities of unsecured debt
2,014	0
2,015	0
2,016	96,337
2,017	87,969
2,018	67,700
Thereafter	123,409
Long-term Debt	$ 375,415

Secured and Unsecured Debt (D72

Secured and Unsecured Debt (Details Textual) - USD ($) $ in Thousands	Jun. 27, 2014	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Secured Debt (Textual) [Abstract]
Secured debt amount which encumbers real estate owned based upon book value		$ 2,200,000		$ 2,200,000
Percentage of secured debt which encumbers real estate owned based upon book value		26.60%		26.60%
Secured debt amount of real estate owned which is unencumbered		$ 6,200,000		$ 6,200,000
Percentage of secured debt of real estate owned which is unencumbered		73.40%		73.40%
Weighted average interest rate		3.58%
Unamortized fair market adjustment		$ 5,700		$ 5,700		$ 6,700
Borrowings outstanding		2,300		$ 2,300		1,900
Extension period of option on loan				6 months
Line of Credit Facility, Interest Rate Description				100
Line of Credit Facility, Commitment Fee Description				15
Fixed Rate Debt [Member]
Secured Debt (Textual) [Abstract]
Secured debt including debt on real estate held for sale		$ 975,024		$ 975,024		969,296
Weighted average interest rate		5.28%
Variable Rate Debt [Member]
Secured Debt (Textual) [Abstract]
Secured debt including debt on real estate held for sale		$ 375,415		375,415		392,233
Weighted average interest rate		1.45%
3.75 MTN Due July 2024 [Member]
Secured Debt (Textual) [Abstract]
Weighted average interest rate		3.75%
Unamortized fair market adjustment		$ 938		$ 938		990
Debt Instrument, Maturity Date	Jul. 1, 2024
Mortgages Notes Payable [Member] | Fixed Rate Debt [Member]
Secured Debt (Textual) [Abstract]
Weighted average interest rate		5.50%
Debt Instrument, Maturity Date Range, Start				Dec. 9, 2015
Debt instrument, maturity date range, end				May 1, 2019
Notes payable minimum interest rates range				3.43%
Notes payable maximum interest rates range				6.16%
Mortgages Notes Payable [Member] | Variable Rate Debt [Member]
Secured Debt (Textual) [Abstract]
Weighted average interest rate		1.94%
Debt Assumed As Part of Acquisition [Member]
Secured Debt (Textual) [Abstract]
Amortization of Debt Discount (Premium)		$ 1,300	$ 1,200	$ 2,400	$ 2,500
Tax Exempt Notes Payable [Member] | Variable Rate Debt [Member]
Secured Debt (Textual) [Abstract]
Weighted average interest rate		0.84%
Fannie Mae credit facilities [Member] | Fixed Rate Debt [Member]
Secured Debt (Textual) [Abstract]
Debt, Weighted Average Interest Rate		5.12%		5.12%
Debt Instrument, Maturity Date Range, Start				May 1, 2017
Debt instrument, maturity date range, end				Jul. 1, 2023
Fannie Mae credit facilities [Member] | Variable Rate Debt [Member]
Secured Debt (Textual) [Abstract]
Debt Instrument, Interest Rate at Period End		1.63%		1.63%
Tax Exempt Secured Notes Payable [Member] | Variable Rate Debt [Member]
Secured Debt (Textual) [Abstract]
Debt Instrument, Maturity Date Range, Start				Aug. 1, 2019
Debt instrument, maturity date range, end				Mar. 20, 2032
Notes payable minimum interest rates range				0.84%
Notes payable maximum interest rates range				0.85%
Fannie Mae [Member]
Secured Debt (Textual) [Abstract]
Borrowings outstanding		$ 815,666		$ 815,666		834,282
1.67% Term Notes due December 2016 [Member]
Secured Debt (Textual) [Abstract]
Weighted average interest rate				1.33%
Debt Instrument, Maturity Date				Jun. 1, 2018
UDR Bank Credit Facility [Member]
Secured Debt (Textual) [Abstract]
Credit facilities with aggregate commitment		900,000		$ 900,000		900,000
Increment in Unsecured Revolving Credit Facility Under Certain Circumstances		1,450,000		1,450,000
Fannie Mae credit facilities [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member] | Fair Value, Measurements, Recurring [Member] | Fannie Mae credit facilities [Member] | Fixed Rate Debt [Member]
Secured Debt (Textual) [Abstract]
Secured debt including debt on real estate held for sale		566,288		566,288		568,086
Fannie Mae credit facilities [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member] | Fair Value, Measurements, Recurring [Member] | Fannie Mae credit facilities [Member] | Variable Rate Debt [Member]
Secured Debt (Textual) [Abstract]
Secured debt including debt on real estate held for sale		249,378		249,378		266,196
Mortgages Notes Payable [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member] | Fair Value, Measurements, Recurring [Member] | Mortgages Notes Payable [Member] | Fixed Rate Debt [Member]
Secured Debt (Textual) [Abstract]
Secured debt including debt on real estate held for sale		408,736		408,736		401,210
Mortgages Notes Payable [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member] | Fair Value, Measurements, Recurring [Member] | Mortgages Notes Payable [Member] | Variable Rate Debt [Member]
Secured Debt (Textual) [Abstract]
Secured debt including debt on real estate held for sale		$ 31,337		$ 31,337		$ 31,337

Secured and Unsecured Debt (D73

Secured and Unsecured Debt (Details Textual 1) - Debt Instrument, Name [Domain] - USD ($) $ in Thousands	Sep. 26, 2013	Jun. 30, 2015	Jun. 30, 2015	Dec. 31, 2014
Unsecured Debt (Textual) [Abstract]
Credit facility interest rate			100
Line of Credit Facility, Commitment Fee Description			15
Line of Credit Facility, Amount Outstanding		$ 2,300	$ 2,300	$ 1,900
Unamortized discount		$ 5,700	5,700	6,700
Debt Instrument, Interest Rate During Period		3.58%
ThreePointSevenTermNotesDueOctober2020 [Member]
Unsecured Debt (Textual) [Abstract]
Debt Instrument, Maturity Date	Oct. 31, 2020
Senior Notes		$ 299,958	$ 299,958	299,954
Debt Instrument, Interest Rate During Period			3.70%
1.67% Term Notes due December 2016 [Member]
Unsecured Debt (Textual) [Abstract]
Debt Instrument, Maturity Date			Jun. 1, 2018
Senior Notes		35,000	$ 35,000	35,000
Debt Instrument, Interest Rate During Period			1.33%
2.90% Term Notes due January 2016 [Member]
Unsecured Debt (Textual) [Abstract]
Senior Notes		215,000	$ 215,000	215,000
Debt Instrument, Interest Rate During Period			1.70%
4.63% Medium-Term Notes due January 2022 [Member]
Unsecured Debt (Textual) [Abstract]
Unamortized discount		2,344	$ 2,344	2,523
Senior Notes		$ 397,656	397,656	397,477
Debt Instrument, Interest Rate During Period		4.63%
2.68% Term Notes due December 2016 [Member]
Unsecured Debt (Textual) [Abstract]
Senior Notes		$ 100,000	$ 100,000	100,000
Debt Instrument, Interest Rate During Period			1.53%
UDR Bank Credit Facility [Member]
Unsecured Debt (Textual) [Abstract]
Total revolving credit facility		900,000	$ 900,000	$ 900,000
Increase in maximum borrowing capacity of unsecured revolving credit facility		$ 1,450,000	$ 1,450,000
Interest rate		1.10%	1.10%	1.10%

Debt (UNITED DOMINION REALTY,74

Debt (UNITED DOMINION REALTY, L.P.) (Details) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2015USD ($)	Jun. 30, 2015USD ($)Communities	Dec. 31, 2014USD ($)
Debt Instrument [Line Items]
Weighted average interest rate	3.58%
Debt Instrument Weighted Average Years to Maturity		4 years 29 days
Fixed Rate Debt [Member]
Debt Instrument [Line Items]
Principal outstanding	$ 975,024	$ 975,024	$ 969,296
Weighted average interest rate	5.28%
Debt Instrument Weighted Average Years to Maturity		2 years 6 months 10 days
Number of Communities Encumbered (in communities)	28
Fixed Rate Debt [Member] | Mortgages Notes Payable [Member]
Debt Instrument [Line Items]
Weighted average interest rate	5.50%
Debt Instrument Weighted Average Years to Maturity		1 year 20 days
Number of Communities Encumbered (in communities)	7
Fixed Rate Debt [Member] | Fannie Mae credit facilities [Member]
Debt Instrument [Line Items]
Debt Instrument Weighted Average Years to Maturity		3 years 6 months 14 days
Number of Communities Encumbered (in communities)	21
Variable Rate Debt [Member]
Debt Instrument [Line Items]
Principal outstanding	$ 375,415	$ 375,415	392,233
Weighted average interest rate	1.45%
Debt Instrument Weighted Average Years to Maturity		5 years 3 months
Number of Communities Encumbered (in communities)	10
Variable Rate Debt [Member] | Mortgages Notes Payable [Member]
Debt Instrument [Line Items]
Weighted average interest rate	1.94%
Debt Instrument Weighted Average Years to Maturity		1 year 6 months 25 days
Number of Communities Encumbered (in communities)	1
Variable Rate Debt [Member] | Fannie Mae credit facilities [Member]
Debt Instrument [Line Items]
Debt Instrument Weighted Average Years to Maturity		4 years 9 months 10 days
Number of Communities Encumbered (in communities)	7
Variable Rate Debt [Member] | Tax Exempt Notes Payable [Member]
Debt Instrument [Line Items]
Weighted average interest rate	0.84%
Debt Instrument Weighted Average Years to Maturity		7 years 8 months 8 days
Number of Communities Encumbered (in communities)	2
United Dominion Reality L.P. [Member]
Debt Instrument [Line Items]
Principal outstanding	$ 912,567	$ 912,567	931,959
Weighted average interest rate		4.43%
Debt Instrument Weighted Average Years to Maturity		3 years 6 months 14 days
Number of Communities Encumbered (in communities) | Communities		20
United Dominion Reality L.P. [Member] | Fixed Rate Debt [Member]
Debt Instrument [Line Items]
Principal outstanding	708,058	$ 708,058	712,199
Weighted average interest rate		5.21%
Debt Instrument Weighted Average Years to Maturity		2 years 6 months
Number of Communities Encumbered (in communities) | Communities		14
United Dominion Reality L.P. [Member] | Fixed Rate Debt [Member] | Mortgages Notes Payable [Member]
Debt Instrument [Line Items]
Principal outstanding	374,056	$ 374,056	378,371
Weighted average interest rate		5.49%
Debt Instrument Weighted Average Years to Maturity		1 year 1 month 6 days
Number of Communities Encumbered (in communities) | Communities		5
United Dominion Reality L.P. [Member] | Fixed Rate Debt [Member] | Fannie Mae credit facilities [Member]
Debt Instrument [Line Items]
Weighted average interest rate		4.90%
Debt Instrument Weighted Average Years to Maturity		4 years 25 days
Number of Communities Encumbered (in communities) | Communities		9
United Dominion Reality L.P. [Member] | Variable Rate Debt [Member]
Debt Instrument [Line Items]
Principal outstanding	204,509	$ 204,509	219,760
Weighted average interest rate		1.74%
Debt Instrument Weighted Average Years to Maturity		7 years 1 month 17 days
Number of Communities Encumbered (in communities) | Communities		6
United Dominion Reality L.P. [Member] | Variable Rate Debt [Member] | Fannie Mae credit facilities [Member]
Debt Instrument [Line Items]
Weighted average interest rate		1.88%
Debt Instrument Weighted Average Years to Maturity		5 years 8 months 1 day
Number of Communities Encumbered (in communities) | Communities		5
United Dominion Reality L.P. [Member] | Variable Rate Debt [Member] | Tax Exempt Notes Payable [Member]
Debt Instrument [Line Items]
Principal outstanding	27,000	$ 27,000	27,000
Weighted average interest rate		0.85%
Debt Instrument Weighted Average Years to Maturity		16 years 8 months 19 days
Number of Communities Encumbered (in communities) | Communities		1
Fannie Mae credit facilities [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member] | Fair Value, Measurements, Recurring [Member] | Fixed Rate Debt [Member] | Fannie Mae credit facilities [Member]
Debt Instrument [Line Items]
Principal outstanding	566,288	$ 566,288	568,086
Fannie Mae credit facilities [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member] | Fair Value, Measurements, Recurring [Member] | Variable Rate Debt [Member] | Fannie Mae credit facilities [Member]
Debt Instrument [Line Items]
Principal outstanding	249,378	249,378	266,196
Fannie Mae credit facilities [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member] | Fair Value, Measurements, Recurring [Member] | United Dominion Reality L.P. [Member] | Fixed Rate Debt [Member] | Fannie Mae credit facilities [Member]
Debt Instrument [Line Items]
Principal outstanding	334,002	334,002	333,828
Fannie Mae credit facilities [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member] | Fair Value, Measurements, Recurring [Member] | United Dominion Reality L.P. [Member] | Variable Rate Debt [Member] | Fannie Mae credit facilities [Member]
Debt Instrument [Line Items]
Principal outstanding	$ 177,509	$ 177,509	$ 192,760

Debt (UNITED DOMINION REALTY,75

Debt (UNITED DOMINION REALTY, L.P.) (Details 1) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2013	Dec. 31, 2014
Debt Instrument [Line Items]
Debt Instrument Weighted Average Years to Maturity	4 years 29 days
Borrowings outstanding	$ 2,300		$ 1,900
Fannie Mae [Member]
Debt Instrument [Line Items]
Borrowings outstanding	815,666		$ 834,282
Weighted average daily borrowings during the period ended	830,434	$ 835,873
Maximum daily borrowings during the period ended	$ 834,003	$ 837,564
Weighted average interest rate during the period ended	4.01%	4.10%
Interest rate at the end of the period	4.05%		4.00%
United Dominion Reality L.P. [Member]
Debt Instrument [Line Items]
Debt Instrument Weighted Average Years to Maturity	3 years 6 months 14 days
United Dominion Reality L.P. [Member] | Fannie Mae [Member]
Debt Instrument [Line Items]
Borrowings outstanding	$ 511,511		$ 526,588
Weighted average daily borrowings during the period ended	520,773	$ 527,592
Maximum daily borrowings during the period ended	$ 523,011	$ 528,659
Weighted average interest rate during the period ended	3.80%	4.10%
Interest rate at the end of the period	3.90%		4.00%
Fixed Rate Debt [Member]
Debt Instrument [Line Items]
Debt Instrument Weighted Average Years to Maturity	2 years 6 months 10 days
Fixed Rate Debt [Member] | Mortgages [Member]
Debt Instrument [Line Items]
Debt Instrument Weighted Average Years to Maturity	1 year 20 days
Fixed Rate Debt [Member] | Line of Credit [Member]
Debt Instrument [Line Items]
Debt Instrument Weighted Average Years to Maturity	3 years 6 months 14 days
Fixed Rate Debt [Member] | United Dominion Reality L.P. [Member]
Debt Instrument [Line Items]
Debt Instrument Weighted Average Years to Maturity	2 years 6 months
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 1 month 6 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 25 days
Variable Rate Debt [Member]
Debt Instrument [Line Items]
Debt Instrument Weighted Average Years to Maturity	5 years 3 months
Variable Rate Debt [Member] | Mortgages [Member]
Debt Instrument [Line Items]
Debt Instrument Weighted Average Years to Maturity	1 year 6 months 25 days
Variable Rate Debt [Member] | Tax Exempt Notes Payable [Member]
Debt Instrument [Line Items]
Debt Instrument Weighted Average Years to Maturity	7 years 8 months 8 days
Variable Rate Debt [Member] | Line of Credit [Member]
Debt Instrument [Line Items]
Debt Instrument Weighted Average Years to Maturity	4 years 9 months 10 days
Variable Rate Debt [Member] | United Dominion Reality L.P. [Member]
Debt Instrument [Line Items]
Debt Instrument Weighted Average Years to Maturity	7 years 1 month 17 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	16 years 8 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	5 years 8 months 1 day

Debt (UNITED DOMINION REALTY,76

Debt (UNITED DOMINION REALTY, L.P.) (Details 2) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
2,014	$ 191,442
2,015	242,692
2,016	731,219
2,017	858,099
2,018	313,571
Thereafter	1,227,380
Total	1,350,439	$ 1,361,529
United Dominion Reality L.P. [Member]
Debt Instrument [Line Items]
2,014	188,943
2,015	132,331
2,016	23,836
2,017	194,500
2,018	173,131
Thereafter	199,826
Total	912,567	$ 931,959
United Dominion Reality L.P. [Member] | Mortgages Notes Payable [Member] | Fixed Rate Debt [Member]
Debt Instrument [Line Items]
2,014	188,759
2,015	131,946
2,016	1,630
2,017	1,685
2,018	50,036
Thereafter	0
Total	374,056
United Dominion Reality L.P. [Member] | Fannie Mae credit facilities [Member] | Fixed Rate Debt [Member]
Debt Instrument [Line Items]
2,014	184
2,015	385
2,016	15,640
2,017	111,256
2,018	123,095
Thereafter	83,442
Total	334,002
United Dominion Reality L.P. [Member] | Fannie Mae credit facilities [Member] | Variable Rate Debt [Member]
Debt Instrument [Line Items]
2,014	0
2,015	0
2,016	6,566
2,017	81,559
2,018	0
Thereafter	89,384
Total	177,509
United Dominion Reality L.P. [Member] | Tax Exempt Notes Payable [Member] | Variable Rate Debt [Member]
Debt Instrument [Line Items]
2,014	0
2,015	0
2,016	0
2,017	0
2,018	0
Thereafter	27,000
Total	$ 27,000

Debt (UNITED DOMINION REALTY,77

Debt (UNITED DOMINION REALTY, L.P.) (Details Textual) - USD ($)	Jun. 27, 2014	Sep. 26, 2013	Jun. 30, 2015	Jun. 30, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Borrowings outstanding			$ 2,300,000	$ 2,300,000	$ 1,900,000
Weighted average interest rate			3.58%
Unamortized fair market adjustment			$ 5,700,000	5,700,000	6,700,000
UDR Bank Credit Facility [Member]
Debt Instrument [Line Items]
Total revolving credit facility			900,000,000	900,000,000	900,000,000
Fixed Rate Debt [Member]
Debt Instrument [Line Items]
Secured debt including debt on real estate held for sale			$ 975,024,000	975,024,000	969,296,000
Weighted average interest rate			5.28%
Variable Rate Debt [Member]
Debt Instrument [Line Items]
Secured debt including debt on real estate held for sale			$ 375,415,000	375,415,000	392,233,000
Weighted average interest rate			1.45%
Fannie Mae [Member]
Debt Instrument [Line Items]
Borrowings outstanding			$ 815,666,000	$ 815,666,000	834,282,000
Fannie Mae credit facilities [Member] | Fixed Rate Debt [Member]
Debt Instrument [Line Items]
Debt Instrument, Maturity Date Range, Start				May 1, 2017
Debt Instrument, Maturity Date Range, End				Jul. 1, 2023
Debt, Weighted Average Interest Rate			5.12%	5.12%
Fannie Mae credit facilities [Member] | Variable Rate Debt [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate at Period End			1.63%	1.63%
Mortgages [Member] | Fixed Rate Debt [Member]
Debt Instrument [Line Items]
Debt Instrument, Maturity Date Range, Start				Dec. 9, 2015
Weighted average interest rate			5.50%
Notes payable minimum interest rates range				3.43%
Notes payable maximum interest rates range				6.16%
Debt Instrument, Maturity Date Range, End				May 1, 2019
Mortgages [Member] | Variable Rate Debt [Member]
Debt Instrument [Line Items]
Weighted average interest rate			1.94%
Tax Exempt Notes Payable [Member] | Variable Rate Debt [Member]
Debt Instrument [Line Items]
Weighted average interest rate			0.84%
Unsecured Revolving Credit Facility due October 2015 [Member]
Debt Instrument [Line Items]
Borrowings outstanding			$ 457,000,000	$ 457,000,000	152,500,000
Weighted average interest rate			1.12%
2.90% Term Notes due January 2016 [Member]
Debt Instrument [Line Items]
Weighted average interest rate				1.70%
Five Point Two Five Percent, Medium Term Notes, Due January 2016 [Member]
Debt Instrument [Line Items]
Weighted average interest rate				5.25%
4.25% Medium-Term Notes due June 2018 [Member]
Debt Instrument [Line Items]
Weighted average interest rate				4.25%
Unamortized fair market adjustment			$ 1,251,000	$ 1,251,000	1,465,000
Three point seven percent medium term note due October 2020 [Member]
Debt Instrument [Line Items]
Unamortized fair market adjustment			$ 42,000	$ 42,000	46,000
ThreePointSevenTermNotesDueOctober2020 [Member]
Debt Instrument [Line Items]
Weighted average interest rate				3.70%
Debt Instrument, Maturity Date		Oct. 31, 2020
4.63% Medium-Term Notes due January 2022 [Member]
Debt Instrument [Line Items]
Weighted average interest rate			4.63%
Unamortized fair market adjustment			$ 2,344,000	$ 2,344,000	2,523,000
3.75 MTN Due July 2024 [Member]
Debt Instrument [Line Items]
Weighted average interest rate			3.75%
Unamortized fair market adjustment			$ 938,000	938,000	990,000
Debt Instrument, Maturity Date	Jul. 1, 2024
United Dominion Reality L.P. [Member]
Debt Instrument [Line Items]
Debt Instrument, Unamortized Premium			4,200,000	4,200,000	6,200,000
Secured debt including debt on real estate held for sale			912,567,000	$ 912,567,000	931,959,000
Weighted average interest rate				4.43%
United Dominion Reality L.P. [Member] | Fixed Rate Debt [Member]
Debt Instrument [Line Items]
Secured debt including debt on real estate held for sale			708,058,000	$ 708,058,000	712,199,000
Weighted average interest rate				5.21%
United Dominion Reality L.P. [Member] | Variable Rate Debt [Member]
Debt Instrument [Line Items]
Secured debt including debt on real estate held for sale			204,509,000	$ 204,509,000	219,760,000
Weighted average interest rate				1.74%
United Dominion Reality L.P. [Member] | Fannie Mae [Member]
Debt Instrument [Line Items]
Borrowings outstanding			511,511,000	$ 511,511,000	526,588,000
United Dominion Reality L.P. [Member] | Fannie Mae credit facilities [Member] | Fixed Rate Debt [Member]
Debt Instrument [Line Items]
Weighted average interest rate				4.90%
United Dominion Reality L.P. [Member] | Fannie Mae credit facilities [Member] | Variable Rate Debt [Member]
Debt Instrument [Line Items]
Weighted average interest rate				1.88%
United Dominion Reality L.P. [Member] | Mortgages [Member] | Fixed Rate Debt [Member]
Debt Instrument [Line Items]
Secured debt including debt on real estate held for sale			374,056,000	$ 374,056,000	378,371,000
Weighted average interest rate				5.49%
Notes payable maximum interest rates range				5.94%
United Dominion Reality L.P. [Member] | Tax Exempt Notes Payable [Member] | Variable Rate Debt [Member]
Debt Instrument [Line Items]
Secured debt including debt on real estate held for sale			27,000,000	$ 27,000,000	27,000,000
Weighted average interest rate				0.85%
Debt Instrument, Maturity Date Range, End				Mar. 1, 2032
United Dominion Reality L.P. [Member] | 2.90% Term Notes due January 2016 [Member]
Debt Instrument [Line Items]
Debt Instrument, Maturity Date Range, End				Jun. 1, 2018
United Dominion Reality L.P. [Member] | 2.90% Term Notes due January 2016 [Member] | Financial Guarantee [Member]
Debt Instrument [Line Items]
Guarantor borrowing capacity			250,000,000	$ 250,000,000
United Dominion Reality L.P. [Member] | 1.68% Term Notes due December 2016 [Member] | Financial Guarantee [Member]
Debt Instrument [Line Items]
Guarantor borrowing capacity			100,000,000	$ 100,000,000
United Dominion Reality L.P. [Member] | Five Point Two Five Percent, Medium Term Notes, Due January 2016 [Member]
Debt Instrument [Line Items]
Debt Instrument, Maturity Date Range, End				Jun. 1, 2018
United Dominion Reality L.P. [Member] | 4.25% Medium-Term Notes due June 2018 [Member]
Debt Instrument [Line Items]
Debt Instrument, Maturity Date Range, End				Jun. 1, 2018
United Dominion Reality L.P. [Member] | 4.25% Medium-Term Notes due June 2018 [Member] | Financial Guarantee [Member]
Debt Instrument [Line Items]
Guarantor borrowing capacity			300,000,000	$ 300,000,000
United Dominion Reality L.P. [Member] | Three point seven percent medium term note due October 2020 [Member] | Financial Guarantee [Member]
Debt Instrument [Line Items]
Guarantor borrowing capacity			300,000,000	$ 300,000,000
United Dominion Reality L.P. [Member] | 4.63% Medium-Term Notes due January 2022 [Member]
Debt Instrument [Line Items]
Debt Instrument, Maturity Date Range, End				Jan. 1, 2022
United Dominion Reality L.P. [Member] | 4.63% Medium-Term Notes due January 2022 [Member] | Financial Guarantee [Member]
Debt Instrument [Line Items]
Guarantor borrowing capacity			400,000,000	$ 400,000,000
United Dominion Reality L.P. [Member] | 3.75 MTN Due July 2024 [Member] | Financial Guarantee [Member]
Debt Instrument [Line Items]
Guarantor borrowing capacity			300,000,000	300,000,000
Mortgages [Member] | Fair Value, Measurements, Recurring [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member] | Mortgages [Member] | Fixed Rate Debt [Member]
Debt Instrument [Line Items]
Secured debt including debt on real estate held for sale			408,736,000	408,736,000	401,210,000
Mortgages [Member] | Fair Value, Measurements, Recurring [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member] | Mortgages [Member] | Variable Rate Debt [Member]
Debt Instrument [Line Items]
Secured debt including debt on real estate held for sale			31,337,000	31,337,000	31,337,000
Mortgages [Member] | Fair Value, Measurements, Recurring [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member] | United Dominion Reality L.P. [Member]
Debt Instrument [Line Items]
Fixed Rate Secured Debt Instruments Fair Value			374,056,000	374,056,000	378,371,000
Fannie Mae credit facilities [Member] | Fair Value, Measurements, Recurring [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member] | Fannie Mae credit facilities [Member] | Fixed Rate Debt [Member]
Debt Instrument [Line Items]
Secured debt including debt on real estate held for sale			566,288,000	566,288,000	568,086,000
Fannie Mae credit facilities [Member] | Fair Value, Measurements, Recurring [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member] | Fannie Mae credit facilities [Member] | Variable Rate Debt [Member]
Debt Instrument [Line Items]
Secured debt including debt on real estate held for sale			249,378,000	249,378,000	266,196,000
Fannie Mae credit facilities [Member] | Fair Value, Measurements, Recurring [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member] | United Dominion Reality L.P. [Member]
Debt Instrument [Line Items]
Variable Rate Secured Debt Instruments Fair Value			177,509,000	177,509,000	192,760,000
Fixed Rate Secured Debt Instruments Fair Value			334,002,000	334,002,000	333,828,000
Fannie Mae credit facilities [Member] | Fair Value, Measurements, Recurring [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member] | United Dominion Reality L.P. [Member] | Fannie Mae credit facilities [Member] | Fixed Rate Debt [Member]
Debt Instrument [Line Items]
Secured debt including debt on real estate held for sale			334,002,000	334,002,000	333,828,000
Fannie Mae credit facilities [Member] | Fair Value, Measurements, Recurring [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member] | United Dominion Reality L.P. [Member] | Fannie Mae credit facilities [Member] | Variable Rate Debt [Member]
Debt Instrument [Line Items]
Secured debt including debt on real estate held for sale			$ 177,509,000	$ 177,509,000	$ 192,760,000

Income_(Loss) Per Share (Detail

Income/(Loss) Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2013
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Income/(loss) from continuing operations	$ 10,842,000	$ 4,359,000	$ 87,259,000	$ (836,000)
Gains/(loss) on sales of real estate, net of tax	79,042,000	26,709,000	79,042,000	51,003,000
Net Income (Loss) Attributable to Noncontrolling Interest	0	2,000	7,000	6,000
Income/(loss) from continuing operations attributable to UDR, Inc.	86,855,000	29,990,000	160,677,000	48,435,000
Distributions to preferred stockholders - Series E (Convertible)	(931,000)	(931,000)	(1,862,000)	(1,862,000)
Income/(loss) from continuing operations operations attributable to common stockholders	85,924,000	29,059,000	158,815,000	46,573,000
Dilutive Securities, Effect on Basic Earnings Per Share, ESOP Convertible Preferred Stock	931,000	0	0	0
udr_IncomeLossContinuingOperationsAvailableToCommonShareholdersDilutive	86,855,000
Income/(loss) from discontinued operations, net of tax	0	18,000	0	(69,000)
(Income)/loss from discontinued operations attributable to redeemable noncontrolling interest in the Operating Partnership	0	(1,000)	0	2,000
Income/(loss) from discontinued operations attributable to common stockholders	0	17,000	0	(67,000)
Net income/(loss)	89,884,000	31,086,000	166,301,000	50,098,000
Net (income)/loss attributable to noncontrolling interests			(7,000)
Net (income)/loss attributable to redeemable non-controlling interests in Operating Partnership	3,029,000	1,077,000	5,617,000	1,724,000
Net (loss)/income attributable to common stockholders	$ 85,924,000	$ 29,076,000	$ 158,815,000	$ 46,506,000
Denominator for earnings per share - basic and diluted:
Weighted average common shares outstanding	259,028	251,458	258,567	251,336
Incremental Common Shares Attributable to Participating Nonvested Shares with Non-forfeitable Dividend Rights	(1,179)	(1,203)	(1,223)	(1,120)
Weighted average number of common shares outstanding — basic	257,849	250,255	257,344	250,216
Incremental shares issuable for assumed conversion of: Stock options and unvested restricted stock	(4,957)	(1,936)	(1,923)	(1,875)
Weighted average number of common shares outstanding — diluted	262,806	252,191	259,267	252,091
Income/(loss) from continuing operations attributable to common stockholders	$ 0.33	$ 0.12	$ 0.62	$ 0.19
Net income/(loss) attributable to common stockholders	0.33	0.12	0.62	0.19
Income/(loss) from discontinued operations attributable to common stockholders,	0	0	0	0
Income/(loss) from continuing operations attributable to common stockholders,	0.33	0.12	0.61	0.18
Income from discontinued operations attributable to common stockholders	0	0	0	0
Net income/(loss) attributable to common stockholders	$ 0.33	$ 0.12	$ 0.61	$ 0.18
OP Units [Member]
Denominator for earnings per share - basic and diluted:
Antidilutive securities	9,125	9,316	9,145		9,317
Convertible Preferred Stock [Member]
Denominator for earnings per share - basic and diluted:
Antidilutive securities	3,036	3,036	3,036		3,036
Stock options and unvested restricted stock [Member]
Denominator for earnings per share - basic and diluted:
Antidilutive securities	1,921	1,936	1,923		1,875
RedeemableNoncontrollingInterest [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
(Income)/loss from continuing operations attributable to noncontrolling interest	$ (3,029,000)	$ (1,076,000)	$ (5,617,000)	$ (1,726,000)

Noncontrolling Interests (Detai

Noncontrolling Interests (Details) - Equity Component [Domain] - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Noncontrolling Interest [Line Items]
Net Income (Loss) Attributable to Noncontrolling Interest	$ 0	$ 2	$ 7	$ 6
Redeemable noncontrolling interests in the Operating Partnership	290,278		290,278		$ 282,480
Net Income (Loss) Available to Common Stockholders, Basic	85,924	29,076	158,815	46,506
Change in equity from net income(loss) attributable to common stockholders and conversion of OP Units to UDR Common Stock	89,403	29,267	162,313	46,697
Redeemable noncontrolling interests in the Operating Partnership
Mark to market adjustment to redeemable noncontrolling interests in the Operating Partnership			10,930
Adjustment for conversion of noncontrolling interest of unitholders in Operating Partnership	3,479	191	3,498	191
Net (income)/loss attributable to redeemable non-controlling interests in Operating Partnership	3,029	$ 1,077	5,617	$ 1,724
Distributions to redeemable noncontrolling interests in the Operating Partnership			5,250
Redeemable non-controlling interests in operating partnership	$ 290,278		290,278
Net income attributable to non-controlling interests			$ 7

Related Party Transactions (U80

Related Party Transactions (UNITED DOMINION REALTY, L.P.) (Details) - Long-term Debt, Type [Domain] - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Related Party Transaction [Line Items]
Related party management fees	$ 4,300	$ 3,100	$ 8,600	$ 6,200
United Dominion Reality L.P. [Member]
Related Party Transaction [Line Items]
Limited partnership units owned	183,167,815		183,167,815		183,167,815
Net receivable balances from General Partner	$ 2,956		$ 2,956		$ 13,624
Related Party Transaction, Management Fee Percentage			2.75%
Interest Expense, Related Party	1,151	1,151	$ 2,302	2,302
Notes payable due to General Partner	88,696		88,696		88,696
United Dominion Reality L.P. [Member] | Taxable REIT Subsidiaries [Member]
Related Party Transaction [Line Items]
Net receivable balances from General Partner	(2,956)		$ (2,956)		(13,624)
Related Party Transaction, Management Fee Percentage			2.75%
United Dominion Reality L.P. [Member] | UDR, Inc. [Member]
Related Party Transaction [Line Items]
General and administrative expenses allocated to the Operating Partnership by UDR	$ 5,700	$ 7,200	$ 9,900	$ 13,900
United Dominion Reality L.P. [Member] | UDR, Inc. [Member] | Bottom Dollar Guaranty [Member]
Related Party Transaction [Line Items]
Notes payable due to General Partner					$ 88,700
Note for 83.2 million [Member] | United Dominion Reality L.P. [Member] | UDR, Inc. [Member] | Guaranty Related To Community Acquisition [Member]
Related Party Transaction [Line Items]
Related party guaranty note payable interest rate	5.18%		5.18%
Debt Instrument, Maturity Date Range, End			Aug. 31, 2021
Note for 5 million [Member] | United Dominion Reality L.P. [Member] | UDR, Inc. [Member] | Guaranty Related To Community Acquisition [Member]
Related Party Transaction [Line Items]
Related party guaranty note payable interest rate	5.34%		5.34%
Debt Instrument, Maturity Date Range, End			Dec. 31, 2023

Fair Value of Derivatives and81

Fair Value of Derivatives and Financial Instruments (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notes receivable, net	$ 15,494	$ 14,369
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
Derivative Asset	12	88
Derivative Liability	9,109	10,368
Secured debt instruments - variable rate
Borrowings outstanding	2,300	1,900
Unsecured debt instruments
Redeemable Noncontrolling Interest, Equity, Carrying Amount	290,278
Redeemable noncontrolling interests in the Operating Partnership (d)	290,278	282,480
Carrying (Reported) Amount, Fair Value Disclosure [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notes receivable, net	15,494	14,369
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis
Total assets	15,506	14,457
Unsecured debt instruments
Total liabilities	3,573,512	3,593,473
Carrying (Reported) Amount, Fair Value Disclosure [Member] | Senior Unsecured Notes [Member] | Fair Value, Measurements, Recurring [Member]
Unsecured debt instruments
Unsecured debt instruments (c)	1,756,964	2,069,076
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)	15,863	14,808
Total assets	15,875	14,896
Unsecured debt instruments
Total liabilities	3,671,647	3,721,512
Redeemable noncontrolling interests in the Operating Partnership (d)	290,278	282,480
Estimate of Fair Value, 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	12	88
Derivatives - Interest rate contracts (b)	9,109	10,368
Estimate of Fair Value, Fair Value Disclosure [Member] | Mortgages Notes Payable [Member] | Fair Value, Measurements, Recurring [Member]
Secured debt instruments - fixed rate
Secured debt instruments - fixed rate	420,571	415,663
Secured debt instruments - variable rate
Secured debt instruments - variable rate	31,337	31,337
Estimate of Fair Value, 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
Estimate of Fair Value, Fair Value Disclosure [Member] | Line of Credit [Member] | Fair Value, Measurements, Recurring [Member]
Secured debt instruments - fixed rate
Secured debt instruments - fixed rate	592,916	606,623
Secured debt instruments - variable rate
Secured debt instruments - variable rate	249,378	266,196
Unsecured debt instruments
Unsecured debt instruments (c)		152,500
Estimate of Fair Value, Fair Value Disclosure [Member] | Senior Unsecured Notes [Member] | Fair Value, Measurements, Recurring [Member]
Unsecured debt instruments
Unsecured debt instruments (c)	1,816,636	2,144,125
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	0
Total assets	0	0
Unsecured debt instruments
Total liabilities	0	0
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	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	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	0
Total assets	12	88
Unsecured debt instruments
Total liabilities	9,109	10,368
Redeemable noncontrolling interests in the Operating Partnership (d)	290,278	282,480
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	12	88
Derivatives - Interest rate contracts (b)	9,109	10,368
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	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)	15,863	14,808
Total assets	15,863	14,808
Unsecured debt instruments
Total liabilities	3,662,538	3,711,144
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	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	420,571	415,663
Secured debt instruments - variable rate
Secured debt instruments - variable rate	31,337	31,337
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	592,916	606,623
Secured debt instruments - variable rate
Secured debt instruments - variable rate	249,378	266,196
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)	457,000	152,500
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)	1,816,636	2,144,125
Unsecured Revolving Credit Facility due October 2015 [Member]
Secured debt instruments - variable rate
Borrowings outstanding	457,000	152,500
Variable Rate Debt [Member]
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis
Secured debt including debt on real estate held for sale	375,415	392,233
Variable Rate Debt [Member] | Tax Exempt Notes Payable [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member] | Tax Exempt Notes Payable [Member] | Fair Value, Measurements, Recurring [Member]
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis
Secured debt including debt on real estate held for sale	94,700	94,700
Variable Rate Debt [Member] | Line of Credit [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member] | Line of Credit [Member] | Fair Value, Measurements, Recurring [Member]
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis
Secured debt including debt on real estate held for sale	249,378	266,196
Variable Rate Debt [Member] | Mortgages Notes Payable [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member] | Mortgages Notes Payable [Member] | Fair Value, Measurements, Recurring [Member]
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis
Secured debt including debt on real estate held for sale	31,337	31,337
Fixed Rate Debt [Member]
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis
Secured debt including debt on real estate held for sale	975,024	969,296
Fixed Rate Debt [Member] | Line of Credit [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member] | Line of Credit [Member] | Fair Value, Measurements, Recurring [Member]
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis
Secured debt including debt on real estate held for sale	566,288	568,086
Fixed Rate Debt [Member] | Mortgages Notes Payable [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member] | Mortgages Notes Payable [Member] | Fair Value, Measurements, Recurring [Member]
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis
Secured debt including debt on real estate held for sale	$ 408,736	$ 401,210

Fair Value of Derivatives and82

Fair Value of Derivatives and Financial Instruments (UNITED DOMINION REALTY, L.P.) (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
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	$ 15,506	$ 14,457
Secured debt instruments - variable rate
Total liabilities	3,573,512	3,593,473
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	7	39
Secured debt instruments - variable rate
Total liabilities	913,003	932,877
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
Derivatives - Interest rate contracts	7	39
Derivative Liability Designated as Hedging Instrument, Fair Value	436	918
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	374,056	378,371
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	334,002	333,828
Secured debt instruments - variable rate
Secured debt instruments - variable rate	177,509	192,760
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	7	39
Derivative Liability Designated as Hedging Instrument, Fair Value	436	918
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	15,875	14,896
Secured debt instruments - variable rate
Total liabilities	3,671,647	3,721,512
Estimate of Fair Value, 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	12	88
Derivative Liability Designated as Hedging Instrument, Fair Value	9,109	10,368
Estimate of Fair Value, Fair Value Disclosure [Member] | Mortgages Notes Payable [Member] | Fair Value, Measurements, Recurring [Member]
Secured debt instruments - fixed rate
Secured debt instruments - fixed rate	420,571	415,663
Secured debt instruments - variable rate
Secured debt instruments - variable rate	31,337	31,337
Estimate of Fair Value, 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
Estimate of Fair Value, Fair Value Disclosure [Member] | Line of Credit [Member] | Fair Value, Measurements, Recurring [Member]
Secured debt instruments - fixed rate
Secured debt instruments - fixed rate	592,916	606,623
Secured debt instruments - variable rate
Secured debt instruments - variable rate	249,378	266,196
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	0
Secured debt instruments - variable rate
Total liabilities	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	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	12	88
Secured debt instruments - variable rate
Total liabilities	9,109	10,368
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	12	88
Derivative Liability Designated as Hedging Instrument, Fair Value	9,109	10,368
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	15,863	14,808
Secured debt instruments - variable rate
Total liabilities	3,662,538	3,711,144
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	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	420,571	415,663
Secured debt instruments - variable rate
Secured debt instruments - variable rate	31,337	31,337
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	592,916	606,623
Secured debt instruments - variable rate
Secured debt instruments - variable rate	249,378	266,196
Estimate of Fair Value, 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	7	39
Secured debt instruments - variable rate
Total liabilities	939,488	967,983
Estimate of Fair Value, 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
Derivatives - Interest rate contracts	7	39
Derivative Liability Designated as Hedging Instrument, Fair Value	436	918
Estimate of Fair Value, 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	384,909	391,835
Estimate of Fair Value, 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
Estimate of Fair Value, 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	349,634	355,470
Secured debt instruments - variable rate
Secured debt instruments - variable rate	177,509	192,760
Estimate of Fair Value, Fair Value Disclosure [Member] | 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	0
Secured debt instruments - variable rate
Total liabilities	0	0
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	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] | Fair Value, Measurements, Recurring [Member]
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis
Total assets	7	39
Secured debt instruments - variable rate
Total liabilities	436	918
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	7	39
Derivative Liability Designated as Hedging Instrument, Fair Value	436	918
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] | Fair Value, Measurements, Recurring [Member]
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis
Total assets	0	0
Secured debt instruments - variable rate
Total liabilities	939,052	967,065
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	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	384,909	391,835
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	349,634	355,470
Secured debt instruments - variable rate
Secured debt instruments - variable rate	$ 177,509	$ 192,760

Derivatives and Hedging Activ83

Derivatives and Hedging Activity (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015USD ($)instruments	Jun. 30, 2014	Jun. 30, 2015USD ($)instruments	Jun. 30, 2014
Derivative [Line Items]
Ineffectiveness on Interest Rate Fair Value Hedges is Immaterial	0	3	0	3
Designated as Hedging Instrument [Member] | Interest rate swaps [Member]
Derivative [Line Items]
Number instruments	9		9
Notional	$ 565,000		$ 565,000
Designated as Hedging Instrument [Member] | Interest rate caps [Member]
Derivative [Line Items]
Number instruments	2		2
Notional	$ 219,984		$ 219,984
Not Designated as Hedging Instrument [Member] | Interest rate caps [Member]
Derivative [Line Items]
Number instruments | instruments	2		2
Notional	$ 116,289		$ 116,289

Derivatives and Hedging Activ84

Derivatives and Hedging Activity (Details 1) $ in Thousands	Jun. 30, 2015USD ($)instruments	Dec. 31, 2014USD ($)
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	$ 9	$ 86
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	3	2
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	9,109	10,368
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
Interest rate caps [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Number of Interest Rate Derivatives Held	2
Fair value of Company's derivative financial instruments and their classification on Consolidated Balance Sheet
Notional	$ 219,984
Interest rate caps [Member] | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Number of Interest Rate Derivatives Held | instruments	2
Fair value of Company's derivative financial instruments and their classification on Consolidated Balance Sheet
Notional	$ 116,289

Derivatives and Hedging Activ85

Derivatives and Hedging Activity (Details 2) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Effect of derivative instruments on the Consolidated Statements of Operations
Unrealized holding gain/(loss)	$ 6,186	$ 304	$ (1,366)	$ 249
Amount of Gain or (Loss) Recognized in Income on Derivative	(22)	0	(24)	0
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) Reclassified from Accumulated OCI into Income (Effective Portion)	(292)	(1,145)	(1,029)	(2,677)
Amount of Gain or (Loss) Recognized in Income on Derivative (Ineffective Portion and Amount Excluded from Effectiveness Testing)	$ 0	$ 3	$ 0	$ 3

Derivatives and Hedging Activ86

Derivatives and Hedging Activity (Details 3) - Fair Value, Measurement Frequency [Domain] - Portion at Fair Value Measurement [Member] - Fair Value by Asset Class [Domain] - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Offsetting Derivative Assets [Abstract]
Gross Amounts Offset in the Consolidated Balance Sheets	$ 0	$ 0
Net Amounts of Assets Presented in the Consolidated Balance Sheets (a)	12	88
Gross Amounts Not Offset in the Consolidated Balance Sheets, Financial Instruments	0	(27)
Gross Amounts Not Offset in the Consolidated Balance Sheets, Cash Collateral Received	0	0
Net Amount	12	61
Offsetting Derivative Liabilities [Abstract]
Gross Amounts Offset in the Consolidated Balance Sheets	0	0
Net Amounts of Liabilities Presented in the Consolidated Balance Sheets (b)	9,109	10,368
Gross Amounts Not Offset in the Consolidated Balance Sheets, Financial Instruments	0	(27)
Gross Amounts Not Offset in the Consolidated Balance Sheets, Cash Collateral Received	0	0
Net Amount	$ 9,109	$ 10,341

Derivatives and Hedging Activ87

Derivatives and Hedging Activity (Details Textual) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
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	0	3	0	3
Estimated additional accumulated other comprehensive Income/(Loss) transferred to interest expense	$ 2,600		$ 2,600
Derivative instruments not designated as hedging instruments, gain (loss), net	(22)	$ 0	(24)	$ 0
Payment required to pay for contract termination	10,700		10,700
Other Income Expense [Member] | Interest Rate Contracts [Member]
Derivatives And Hedging Activity (Textual) [Abstract]
Derivative instruments not designated as hedging instruments, gain (loss), net	$ 0	$ 0	$ 0	$ 0

Derivatives and Hedging Activ88

Derivatives and Hedging Activity (UNITED DOMINION REALTY, L.P.) (Details) - Jun. 30, 2015 $ in Thousands	USD ($)instruments
Designated as Hedging Instrument [Member] | Interest rate swaps [Member]
Derivative [Line Items]
Number instruments	9
Outstanding interest rate derivatives not designated as hedging instrument
Notional	$ 565,000
Designated as Hedging Instrument [Member] | Interest rate caps [Member]
Derivative [Line Items]
Number instruments	2
Outstanding interest rate derivatives not designated as hedging instrument
Notional	$ 219,984
Not Designated as Hedging Instrument [Member] | Interest rate caps [Member]
Derivative [Line Items]
Number instruments | instruments	2
Outstanding interest rate derivatives not designated as hedging instrument
Notional	$ 116,289
United Dominion Reality L.P. [Member] | Designated as Hedging Instrument [Member] | Interest rate swaps [Member]
Derivative [Line Items]
Number instruments	1
Outstanding interest rate derivatives not designated as hedging instrument
Notional	$ 46,357
United Dominion Reality L.P. [Member] | Designated as Hedging Instrument [Member] | Interest rate caps [Member]
Derivative [Line Items]
Number instruments	1
Outstanding interest rate derivatives not designated as hedging instrument
Notional	$ 143,508
United Dominion Reality L.P. [Member] | Not Designated as Hedging Instrument [Member] | Interest rate caps [Member]
Derivative [Line Items]
Number instruments | instruments	2
Outstanding interest rate derivatives not designated as hedging instrument
Notional	$ 109,264

Derivatives and Hedging Activ89

Derivatives and Hedging Activity (UNITED DOMINION REALTY, L.P.) (Details 1) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
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	$ 9	$ 86
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	3	2
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	9,109	10,368
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	7	39
Derivative Liability Designated as Hedging Instrument, Fair Value	436	918
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	4	37
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	3	2
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	436	918
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

Derivatives and Hedging Activ90

Derivatives and Hedging Activity (UNITED DOMINION REALTY, L.P.) (Details 2) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2013
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized holding gain/(loss)	$ 6,186,000	$ 304,000	$ (1,366,000)	$ 249,000
Amount of Gain or (Loss) Recognized in Income on Derivative	(22,000)	0	(24,000)	0
Interest Rate Products [Member] | Other Income Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Recognized in Income on Derivative	0	0	0	0
Interest Rate Products [Member] | Interest Expense [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	(292,000)	(1,145,000)	(1,029,000)	(2,677,000)
United Dominion Reality L.P. [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized holding gain/(loss)	(26,000)	(140,000)	(77,000)	(191,000)
Amount of Gain or (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	267,000	573,000	553,000	$ 1,196,000
Amount of Gain or (Loss) Recognized in Income on Derivative	(22,000)	0	0
United Dominion Reality L.P. [Member] | Interest Rate Products [Member] | Other Income Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Recognized in Income on Derivative			(23,000)		$ 0
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) Reclassified from Accumulated OCI into Income (Effective Portion)	$ (267,000)	$ (573,000)	$ (553,000)		$ (1,196,000)

Derivatives and Hedging Activ91

Derivatives and Hedging Activity (UNITED DOMINION REALTY, L.P.) (Details 3) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Offsetting Derivative Assets [Abstract]
Gross Amounts Offset in the Consolidated Balance Sheets	$ 0	$ 0
Net Amounts of Assets Presented in the Consolidated Balance Sheets (a)	12	88
Gross Amounts Not Offset in the Consolidated Balance Sheets, Financial Instruments	0	27
Gross Amounts Not Offset in the Consolidated Balance Sheets, Cash Collateral Received	0	0
Net Amount	12	61
Offsetting Derivative Liabilities [Abstract]
Gross Amounts Offset in the Consolidated Balance Sheets	0	0
Net Amounts of Liabilities Presented in the Consolidated Balance Sheets (b)	9,109	10,368
Gross Amounts Not Offset in the Consolidated Balance Sheets, Financial Instruments	0	27
Gross Amounts Not Offset in the Consolidated Balance Sheets, Cash Collateral Received	0	0
Net Amount	9,109	10,341
United Dominion Reality L.P. [Member]
Offsetting Derivative Assets [Abstract]
Derivative Asset Designated as Hedging Instrument, Fair Value	7	39
Gross Amounts Offset in the Consolidated Balance Sheets	0	0
Net Amounts of Assets Presented in the Consolidated Balance Sheets (a)	7	39
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	7	39
Offsetting Derivative Liabilities [Abstract]
Derivative Liability Designated as Hedging Instrument, Fair Value	436	918
Gross Amounts Offset in the Consolidated Balance Sheets	0	0
Net Amounts of Liabilities Presented in the Consolidated Balance Sheets (b)	436	918
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	$ 436	$ 918

Derivatives and Hedging Activ92

Derivatives and Hedging Activity (UNITED DOMINION REALTY, L.P.) (Details Textual) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Entity Information [Line Items]
Cash flow hedge ineffectiveness in earnings materiality	0	3	0	3
Estimated additional accumulated other comprehensive Income/(Loss) transferred to interest expense	$ 2,600,000		$ 2,600,000
Losses in the fair value of derivatives not designated in hedging relationships	22,000	$ 0	24,000	$ 0
Payment required to pay for contract termination	10,700,000		10,700,000
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	0	0	0	0
Estimated additional accumulated other comprehensive Income/(Loss) transferred to interest expense	$ 440,000		$ 440,000
Losses in the fair value of derivatives not designated in hedging relationships	22,000	$ 0	0
Fair value of derivatives in a net liability position	436,000		436,000
Derivative, Collateral, Obligation to Return Cash	$ 0		$ 0		$ 0

Stock Based Compensation (Detai

Stock Based Compensation (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Stock Based Compensation (Textual) [Abstract]
Stock based compensation expense	$ 5.1	$ 3.6	$ 9.6	$ 7.3

Capital Structure (UNITED DOM94

Capital Structure (UNITED DOMINION REALTY, L.P.) (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2015USD ($)$ / Unitsshares	Dec. 31, 2014USD ($)shares
Limited Partners' Capital Account [Line Items]
Redeemable Noncontrolling Interest, Equity, Carrying Amount | $	$ 290,278
Percentage of units	4.90%
Redeemable noncontrolling interests in the Operating Partnership | $	$ 290,278	$ 282,480
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	174,105,126	174,002,342
Percentage of units	95.10%	95.00%
Non-affiliated Partners [Member]
Limited Partners' Capital Account [Line Items]
Limited partnership units owned	9,062,689	9,165,473
Percentage of units	4.90%	5.00%
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) | $ / Units	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	1,873,332
Class A Limited Partner [Member] | UDR, Inc. [Member]
Limited Partners' Capital Account [Line Items]
Limited partnership units owned	121,661

Commitments and Contingencies95

Commitments and Contingencies (Details) - Jun. 30, 2015 $ in Thousands	USD ($)Communities
Real Estate Properties [Line Items]
Number of communities owned (in communities) | Communities	136
Costs Incurred to Date	$ 647,838
Expected Costs to Complete	436,828
Wholly owned — under development [Member]
Real Estate Properties [Line Items]
Capital Expenditures Incurred but Not yet Paid	$ 100
Number of communities owned (in communities)	1
Costs Incurred to Date	$ 92,645
Expected Costs to Complete	$ 249,355
Average Ownership Stake	100.00%
Wholly owned — redevelopment [Member]
Real Estate Properties [Line Items]
Capital Expenditures Incurred but Not yet Paid	$ 1,300
Number of communities owned (in communities)	1
Costs Incurred to Date	$ 4,854
Expected Costs to Complete	$ 10,146
Average Ownership Stake	100.00%
Unconsolidated joint ventures [Member]
Real Estate Properties [Line Items]
Number of communities owned (in communities)	4
Costs Incurred to Date	$ 335,539
Expected Costs to Complete	$ 163,791
Participating Loan Investment Steele Creek Denver Colorado [Member]
Real Estate Properties [Line Items]
Number of communities owned (in communities)	1
Costs Incurred to Date	$ 85,208
Expected Costs to Complete	$ 6,801
Average Ownership Stake	0.00%
Preferred Equity Investment West Coast Development JV [Member]
Real Estate Properties [Line Items]
Number of communities owned (in communities)	5
Costs Incurred to Date	$ 129,592
Expected Costs to Complete	$ 6,735
Average Ownership Stake	48.00%

Commitments and Contingencies96

Commitments and Contingencies (UNITED DOMINION REALTY, L.P.) Commitments and Contingencies (Details) - Jun. 30, 2015 $ in Thousands	USD ($)Communities
Loss Contingencies [Line Items]
Number of communities owned (in communities) | Communities	136
Cost Incurred to Date	$ 647,838
Expected Costs to Complete	$ 436,828
United Dominion Reality L.P. [Member]
Loss Contingencies [Line Items]
Number of communities owned (in communities) | Communities	67
Wholly owned — redevelopment [Member]
Loss Contingencies [Line Items]
Capital Expenditures Incurred but Not yet Paid	$ 1,300
Number of communities owned (in communities)	1
Cost Incurred to Date	$ 4,854
Expected Costs to Complete	10,146
Wholly owned — redevelopment [Member] | United Dominion Reality L.P. [Member]
Loss Contingencies [Line Items]
Capital Expenditures Incurred but Not yet Paid	$ 1,300
Number of communities owned (in communities)	1
Cost Incurred to Date	$ 4,854
Expected Costs to Complete	10,146
Wholly owned — under development [Member]
Loss Contingencies [Line Items]
Capital Expenditures Incurred but Not yet Paid	$ 100
Number of communities owned (in communities)	1
Cost Incurred to Date	$ 92,645
Expected Costs to Complete	$ 249,355

Reportable Segments (Details)

Reportable Segments (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015USD ($)Segments	Jun. 30, 2014USD ($)	Jun. 30, 2015USD ($)	Jun. 30, 2014USD ($)	Jun. 30, 2013USD ($)	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)
Segment Reporting Information [Line Items]
Same Store Communities	35,250		35,250
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	$ 215,862	$ 203,706	$ 435,615	$ 401,745
Reportable apartment home segment NOI	150,432	140,392	294,007	272,516
Reconciling items:
Joint venture management and other fees	3,098	2,747	15,804	6,434
Property management	5,851	5,529	(11,545)	(10,875)
Other operating expenses	(1,769)	(2,171)	(3,535)	(4,106)
Segment Reporting Reconciling Items Cost of Services Depreciation and Amortization	(90,344)	(88,876)	(179,121)	(177,409)
General and administrative	(13,721)	(12,530)	(25,873)	(24,524)
Casualty (Recoveries)/Charges	(843)	0	(1,839)	(500)
Casualty-related (recoveries)/charges, net	843	0	1,839	500
Other depreciation and amortization	(1,700)	(1,193)	(3,323)	(2,273)
Income/(loss) from unconsolidated entities	573	428	(58,586)	3,993
Interest expense	29,673	31,691	58,473	64,575
Interest and other income/(expense), net	382	1,426	742	2,841
Gains/(loss) on sales of real estate, net of tax	79,042	26,709	79,042	51,003
Tax benefit, net	1,404	2,230	1,829	5,559
Gain on sale of real estate owned, net of tax			79,042	51,003
Gain Loss on the Sale of Real Estate, Including Discontinued Operations	79,042		79,042
Net (income)/loss attributable to redeemable noncontrolling interests in the Operating Partnership	(3,029)	(1,077)	(5,617)	(1,724)
Net (income)/loss attributable to noncontrolling interests	0	2	(7)	(6)
Net income/(loss) attributable to UDR, Inc.	86,855	30,007	160,677	48,368
Reportable apartment home segment assets:
Total segment assets	8,425,279		8,425,279			$ 8,383,259
Accumulated depreciation	(2,557,949)		(2,557,949)			(2,434,772)
Total segment asset - net book value	5,867,330		5,867,330			5,948,487
Reconciling items:
Cash and cash equivalents	2,990	$ 26,816	2,990	$ 26,816		15,224	$ 30,249
Deferred financing costs, net	19,930		19,930			22,686
Notes receivable, net	15,494		15,494			14,369
Other assets	96,259		96,259			105,202
Total consolidated assets	$ 6,939,730		$ 6,939,730			6,846,534
Reportable Segment (Textual) [Abstract]
Number of reportable segments | Segments	2
Condition for Community considered to have stabilized occupancy			0.9
Number of Tenants or related group of tenants that contributed 10% or more of company total revenue	0	0	0	0
Restricted Cash and Cash Equivalents	$ 22,912		$ 22,912			22,340
Same Communities [Member]
Reportable Segment (Textual) [Abstract]
SEC Schedule III, Real Estate, Improvements	20,600	$ 12,800	33,800	$ 20,300
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	68,646	64,004	135,595	126,405
Reportable apartment home segment NOI	51,400	46,496	100,999	91,287
Reportable apartment home segment assets:
Total segment assets	2,608,586		2,608,586			2,592,156
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	43,536	42,644	86,331	84,694
Reportable apartment home segment NOI	30,302	29,863	59,590	58,699
Reportable apartment home segment assets:
Total segment assets	1,541,420		1,541,420			1,533,993
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	21,436	20,294	42,328	40,096
Reportable apartment home segment NOI	16,269	15,459	31,835	30,004
Reportable apartment home segment assets:
Total segment assets	1,081,035		1,081,035			1,076,656
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	26,540	25,063	52,505	49,774
Reportable apartment home segment NOI	17,876	16,769	35,207	33,465
Reportable apartment home segment assets:
Total segment assets	738,595		738,595			733,068
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	14,363	13,623	28,470	27,090
Reportable apartment home segment NOI	8,998	8,263	17,534	16,621
Reportable apartment home segment assets:
Total segment assets	443,526		443,526			440,721
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	38,243	35,409	74,582	67,378
Reportable apartment home segment NOI	25,587	23,542	48,842	42,440
Reportable apartment home segment assets:
Total segment assets	2,012,117		2,012,117			2,006,665
Reportable Segment (Textual) [Abstract]
SEC Schedule III, Real Estate, Improvements	1,200	2,500	3,800	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	$ 212,764	201,037	$ 419,811	395,437
Segment Reconciling Items [Member]
Reconciling items:
Gain Loss on the Sale of Real Estate, Including Discontinued Operations		26,709		51,003
United Dominion Reality L.P. [Member]
Segment Reporting Information [Line Items]
Same Store Communities	18,969		18,969
Summary of rental income and NOI for UDRs reportable segments and reconciliation of NOI to loss from continuing operations
Reportable apartment home segment NOI	$ 82,283	74,968	$ 160,398		$ 147,385
Reconciling items:
Property management	(3,112)	(2,883)	(6,139)		(5,698)
Other operating expenses	(1,496)	(1,451)	(2,986)		(2,887)
Real estate depreciation and amortization	44,100	44,697	88,578	88,968
General and administrative	(7,032)	(7,459)	(12,671)		(14,429)
Casualty (Recoveries)/Charges	(280)	0	(873)	(500)
Casualty-related (recoveries)/charges, net	(280)	0	(873)		(500)
Interest expense	10,908	10,159	21,679		20,173
Gains/(loss) on sales of real estate, net of tax	32,375	16,285	56,998	40,687
Net (income)/loss attributable to noncontrolling interests	(347)	(178)	(741)		(458)
Net income/(loss) attributable to UDR, Inc.	47,383	24,426	83,729	54,959	54,959
Reportable apartment home segment assets:
Total segment assets	4,238,995		4,238,995			4,238,770
Total segment asset - net book value	2,764,161		2,764,161			2,835,467
Reconciling items:
Cash and cash equivalents	164	$ 1,175	164	$ 1,175		502	$ 1,897
Deferred financing costs, net	3,707		3,707			4,475
Other assets	23,090		23,090			24,029
Total consolidated assets	$ 2,805,578		$ 2,805,578			2,878,284
Reportable Segment (Textual) [Abstract]
Related Party Transaction, Management Fee Percentage			2.75%
Number of reportable segments | Segments	2
Number of Tenants or related group of tenants that contributed 10% or more of company total revenue	0	0		0
United Dominion Reality L.P. [Member] | Same-Store [Member]
Reportable Segment (Textual) [Abstract]
SEC Schedule III, Real Estate, Improvements	$ 12,500	$ 7,300	$ 20,300	$ 11,200
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	48,175	44,544	95,082		87,916
Reportable apartment home segment NOI	36,447	32,487	71,094		63,958
Reportable apartment home segment assets:
Total segment assets	1,670,364		1,670,364			1,658,042
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	17,613	17,364	34,862		34,610
Reportable apartment home segment NOI	11,894	11,900	23,360		23,466
Reportable apartment home segment assets:
Total segment assets	716,152		716,152			713,093
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	6,868	6,653	13,605		13,206
Reportable apartment home segment NOI	4,361	4,168	8,574		8,386
Reportable apartment home segment assets:
Total segment assets	780,235		780,235			777,376
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	11,870	11,254	23,549		22,385
Reportable apartment home segment NOI	7,938	7,503	15,648		14,959
Reportable apartment home segment assets:
Total segment assets	335,662		335,662			333,428
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	15,497	14,658	30,570		28,925
Reportable apartment home segment NOI	12,074	11,415	23,647		22,053
Reportable apartment home segment assets:
Total segment assets	230,330		230,330			228,996
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	13,135	10,369	25,585		20,170
Reportable apartment home segment NOI	9,569	7,495	18,075		14,563
Reportable apartment home segment assets:
Total segment assets	506,252		506,252			$ 527,835
Reportable Segment (Textual) [Abstract]
SEC Schedule III, Real Estate, Improvements	668	326	1,167	$ 615
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	113,158	104,842	$ 223,253		207,212
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] | United Dominion Reality L.P. [Member]
Reconciling items:
Real estate depreciation and amortization	$ 44,100	$ 44,697	$ 88,578		$ 88,968

Reportable Segments (UNITED D98

Reportable Segments (UNITED DOMINION REALTY, L.P.) (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015USD ($)Segments	Jun. 30, 2014USD ($)	Jun. 30, 2015USD ($)	Jun. 30, 2014USD ($)	Jun. 30, 2013USD ($)	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)
Segment Reporting Information [Line Items]
Same Store Communities	35,250		35,250
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	$ 215,862	$ 203,706	$ 435,615	$ 401,745
Reportable apartment home segment NOI	(150,432)	(140,392)	(294,007)	(272,516)
Reconciling items:
Property management	5,851	5,529	(11,545)	(10,875)
Other operating expenses	(1,769)	(2,171)	(3,535)	(4,106)
General and administrative	(13,721)	(12,530)	(25,873)	(24,524)
Casualty-related (recoveries)/charges, net	843	0	1,839	500
Interest expense	29,673	31,691	58,473	64,575
Gains/(loss) on sales of real estate owned	79,042	26,709	79,042	51,003
Net (income)/loss attributable to noncontrolling interests	0	2	(7)	(6)
Net income/(loss) attributable to OP unitholders	86,855	30,007	160,677	48,368
Reportable apartment home segment assets:
Total segment assets	8,425,279		8,425,279			$ 8,383,259
Real Estate Investment Property, Accumulated Depreciation	2,557,949		2,557,949			2,434,772
Accumulated depreciation	(2,557,949)		(2,557,949)			(2,434,772)
Total segment asset - net book value	5,867,330		5,867,330			5,948,487
Reconciling items:
Cash and cash equivalents	2,990	$ 26,816	2,990	$ 26,816		15,224	$ 30,249
Deferred financing costs, net	19,930		19,930			22,686
Other assets	96,259		96,259			105,202
Total assets	$ 6,939,730		$ 6,939,730			6,846,534
Reportable Segment (Textual) [Abstract]
Number of reportable segments | Segments	2
Condition for Community considered to have stabilized occupancy			0.9
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 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	$ 68,646	$ 64,004	$ 135,595	$ 126,405
Reportable apartment home segment NOI	(51,400)	(46,496)	(100,999)	(91,287)
Reportable apartment home segment assets:
Total segment assets	2,608,586		2,608,586			2,592,156
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	43,536	42,644	86,331	84,694
Reportable apartment home segment NOI	(30,302)	(29,863)	(59,590)	(58,699)
Reportable apartment home segment assets:
Total segment assets	1,541,420		1,541,420			1,533,993
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	21,436	20,294	42,328	40,096
Reportable apartment home segment NOI	(16,269)	(15,459)	(31,835)	(30,004)
Reportable apartment home segment assets:
Total segment assets	1,081,035		1,081,035			1,076,656
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	26,540	25,063	52,505	49,774
Reportable apartment home segment NOI	(17,876)	(16,769)	(35,207)	(33,465)
Reportable apartment home segment assets:
Total segment assets	738,595		738,595			733,068
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	14,363	13,623	28,470	27,090
Reportable apartment home segment NOI	(8,998)	(8,263)	(17,534)	(16,621)
Reportable apartment home segment assets:
Total segment assets	443,526		443,526			440,721
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	38,243	35,409	74,582	67,378
Reportable apartment home segment NOI	(25,587)	(23,542)	(48,842)	(42,440)
Reportable apartment home segment assets:
Total segment assets	2,012,117		2,012,117			2,006,665
Reportable Segment (Textual) [Abstract]
SEC Schedule III, Real Estate, Improvements	1,200	2,500	3,800	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	$ 212,764	201,037	$ 419,811	395,437
United Dominion Reality L.P. [Member]
Segment Reporting Information [Line Items]
Same Store Communities	18,969		18,969
Summary of rental income and NOI for UDRs reportable segments and reconciliation of NOI to loss from continuing operations
Reportable apartment home segment NOI	$ (82,283)	(74,968)	$ (160,398)		$ (147,385)
Reconciling items:
Property management	(3,112)	(2,883)	(6,139)		(5,698)
Other operating expenses	(1,496)	(1,451)	(2,986)		(2,887)
Real estate depreciation and amortization	44,100	44,697	88,578	88,968
General and administrative	(7,032)	(7,459)	(12,671)		(14,429)
Casualty-related (recoveries)/charges, net	(280)	0	(873)		(500)
Interest expense	10,908	10,159	21,679		20,173
Gains/(loss) on sales of real estate owned	32,375	16,285	56,998	40,687
Net (income)/loss attributable to noncontrolling interests	(347)	(178)	(741)		(458)
Net income/(loss) attributable to OP unitholders	47,383	24,426	83,729	54,959	54,959
Reportable apartment home segment assets:
Total segment assets	4,238,995		4,238,995			4,238,770
Real Estate Investment Property, Accumulated Depreciation	1,474,834		1,474,834			1,403,303
Total segment asset - net book value	2,764,161		2,764,161			2,835,467
Reconciling items:
Cash and cash equivalents	164	$ 1,175	164	$ 1,175		502	$ 1,897
Restricted Cash	14,456		14,456			13,811
Deferred financing costs, net	3,707		3,707			4,475
Other assets	23,090		23,090			24,029
Total assets	$ 2,805,578		$ 2,805,578			2,878,284
Reportable Segment (Textual) [Abstract]
Number of reportable segments | Segments	2
Number of Tenants or related group of tenants that contributed 10% or more of company total revenue	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	$ 12,500	$ 7,300	$ 20,300	$ 11,200
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	48,175	44,544	95,082		87,916
Reportable apartment home segment NOI	(36,447)	(32,487)	(71,094)		(63,958)
Reportable apartment home segment assets:
Total segment assets	1,670,364		1,670,364			1,658,042
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	17,613	17,364	34,862		34,610
Reportable apartment home segment NOI	(11,894)	(11,900)	(23,360)		(23,466)
Reportable apartment home segment assets:
Total segment assets	716,152		716,152			713,093
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	6,868	6,653	13,605		13,206
Reportable apartment home segment NOI	(4,361)	(4,168)	(8,574)		(8,386)
Reportable apartment home segment assets:
Total segment assets	780,235		780,235			777,376
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	11,870	11,254	23,549		22,385
Reportable apartment home segment NOI	(7,938)	(7,503)	(15,648)		(14,959)
Reportable apartment home segment assets:
Total segment assets	335,662		335,662			333,428
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	15,497	14,658	30,570		28,925
Reportable apartment home segment NOI	(12,074)	(11,415)	(23,647)		(22,053)
Reportable apartment home segment assets:
Total segment assets	230,330		230,330			228,996
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	13,135	10,369	25,585		20,170
Reportable apartment home segment NOI	(9,569)	(7,495)	(18,075)		(14,563)
Reportable apartment home segment assets:
Total segment assets	506,252		506,252			$ 527,835
Reportable Segment (Textual) [Abstract]
SEC Schedule III, Real Estate, Improvements	668	326	1,167	$ 615
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	113,158	104,842	223,253		207,212
Segment Reconciling Items [Member] | United Dominion Reality L.P. [Member]
Reconciling items:
Real estate depreciation and amortization	$ 44,100	$ 44,697	$ 88,578		$ 88,968