Reportable Segments (Details) (USD $)	3 Months Ended	12 Months Ended
	Dec. 31, 2010	Dec. 31, 2011 Tenant	Dec. 31, 2010 Tenant	Dec. 31, 2009 Tenant	Dec. 31, 2008
Reportable apartment home segment rental income
Total segment and consolidated rental income		$ 730,958,000	$ 633,868,000	$ 602,899,000
Reportable apartment home segment NOI
Total segment and consolidated NOI		484,760,000	411,064,000	398,460,000
Reconciling items:
Non-property income		17,422,000	14,347,000	14,274,000
Property management		(20,101,000)	(17,432,000)	(16,581,000)
Other operating expenses		(6,217,000)	(5,848,000)	(6,485,000)
Depreciation and amortization		(370,343,000)	(303,446,000)	(278,391,000)
Interest, net		(158,333,000)	(150,796,000)	(142,152,000)
General and administrative		(45,915,000)	(45,243,000)	(39,035,000)
Severance costs and other restructuring charges	(6,800,000)	(1,342,000)	(6,803,000)
Other depreciation and amortization		(3,931,000)	(4,843,000)	(5,161,000)
Loss from unconsolidated entities		(6,352,000)	(4,204,000)	(18,665,000)
Net (income)/loss attributable to redeemable non-controlling interests in OP		(395,000)	3,835,000	4,282,000
Non-controlling interests		(167,000)	(146,000)	(191,000)
Tax benefit/(expense) for taxable REIT subsidiary		(7,571,000)	2,533,000	(311,000)
Gain on the sale of depreciable property		138,508,000	4,083,000	2,424,000
Net income/(loss) attributable to UDR, Inc.		20,023,000	(102,899,000)	(87,532,000)
Reportable apartment home segment assets:
Total segment assets	6,881,347,000	8,074,471,000	6,881,347,000
Accumulated depreciation	(1,638,326,000)	(1,831,727,000)	(1,638,326,000)
Real estate held for sale (net of accumulated depreciation)	5,243,021,000	6,242,744,000	5,243,021,000
Reconciling items:
Cash and cash equivalents	9,486,000	12,503,000	9,486,000	5,985,000	12,740,000
Marketable securities	3,866,000	0	3,866,000
Restricted cash	15,447,000	24,634,000	15,447,000
Deferred financing costs, net	27,267,000	30,068,000	27,267,000
Notes receivable	7,800,000	0	7,800,000
Investment in unconsolidated joint ventures	148,057,000	213,040,000	148,057,000
Other assets	74,596,000	198,365,000	74,596,000
Total assets	5,529,540,000	6,721,354,000	5,529,540,000
Reportable Segments (Additional) (Textual) [Abstract]
Capital expenditures related to segments		48,300,000	42,600,000	48,000,000
Reportable Segment (Textual) [Abstract]
Condition for Community considered to have stabilized occupancy		90% occupancy for at least three consecutive months
Number of Tenants or related group of tenants that contributed 10% or more of company total revenue		0	0	0
Same Store Communities [Member] | WESTERN REGION [Member]
Reportable apartment home segment rental income
Total segment and consolidated rental income		185,759,000	177,771,000	182,120,000
Reportable apartment home segment NOI
Total segment and consolidated NOI		129,292,000	121,338,000	127,653,000
Reportable apartment home segment assets:
Total segment assets	1,920,742,000	1,958,108,000	1,920,742,000
Same Store Communities [Member] | MID-ATLANTIC REGION [Member]
Reportable apartment home segment rental income
Total segment and consolidated rental income		153,913,000	147,643,000	144,401,000
Reportable apartment home segment NOI
Total segment and consolidated NOI		106,393,000	100,875,000	98,483,000
Reportable apartment home segment assets:
Total segment assets	1,245,737,000	1,257,778,000	1,245,737,000
Same Store Communities [Member] | SOUTHEASTERN REGION [Member]
Reportable apartment home segment rental income
Total segment and consolidated rental income		126,604,000	122,412,000	121,659,000
Reportable apartment home segment NOI
Total segment and consolidated NOI		79,369,000	76,560,000	74,853,000
Reportable apartment home segment assets:
Total segment assets	1,003,830,000	1,041,658,000	1,003,830,000
Same Store Communities [Member] | SOUTHWESTERN [Member]
Reportable apartment home segment rental income
Total segment and consolidated rental income		49,223,000	47,202,000	46,674,000
Reportable apartment home segment NOI
Total segment and consolidated NOI		29,395,000	27,527,000	26,058,000
Reportable apartment home segment assets:
Total segment assets	461,015,000	476,812,000	461,015,000
Non-Mature communities/Other [Member]
Reportable apartment home segment rental income
Total segment and consolidated rental income		215,459,000	138,840,000	108,045,000
Reportable apartment home segment NOI
Total segment and consolidated NOI		140,311,000	84,764,000	71,413,000
Reportable apartment home segment assets:
Total segment assets	2,250,023,000	3,340,115,000	2,250,023,000
Reportable Segments (Additional) (Textual) [Abstract]
Capital expenditures related to segments		$ 9,500,000	$ 6,000,000	$ 8,300,000