Earnings/(Loss) Per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2010
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Income/(loss) from continuing operations	$ 5,354	$ (23,123)	$ 5,045	$ (21,382)
Income (loss) from continuing operations attributable to noncontrolling interest			(114)
Income (loss) from continuing operations attributable to UDR, Inc.	5,192	(22,291)	4,924	(20,671)
Preferred Stock Redemption Premium	0	(2,791)	0	(2,791)
Income (loss) from continuing operations operations applicable to common stockholders	4,261	(26,922)	3,062	(27,610)
Income (loss) from discontinued operations, net	0	179,429	0	264,316	0
Income (loss) from discontinued operations attributable to redeemable noncontrolling interest	0	(6,786)	0	(10,137)
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent	0	172,643	0	254,179
Net income/(loss)	5,354	156,306	5,045	242,934
Net income attributable to non-controlling interests	3	43	7	95
Net (income)/loss attributable to redeemable non-controlling interests in OP	159	5,911	114	9,331
Net loss attributable to common stockholders	4,261	145,721	3,062	226,569
Denominator for earnings per share - basic and diluted:
Weighted average common shares outstanding	250,745,000	234,657,000	250,623,000	228,697,000
Non-vested restricted stock awards	(1,421,000)	0	(1,402,000)	0
Dilutive Securities, Effect on Basic Earnings Per Share, Including Options and Restrictive Stock Units	760	626	(672)	(931)
Denominator for basic and diluted earnings per share	249,985,000	234,031,000	249,951,000	227,766,000
Weighted average number of common shares outstanding — diluted	251,406,000	234,031,000	251,353,000	227,766,000
Income (Loss) from Continuing Operations, Per Basic Share	$ 0.02	$ (0.12)	$ 0.01	$ (0.12)
Earnings Per Share, Basic	$ 0.02	$ 0.62	$ 0.01	$ 0.99
Income from discontinued operations attributable to common stockholders	$ 0.00	$ 0.74	$ 0.00	$ 1.12
Income (Loss) from Continuing Operations, Per Diluted Share	$ 0.02	$ (0.12)	$ 0.01	$ (0.12)
Income from discontinued operations attributable to common stockholders	$ 0.00	$ 0.74	$ 0.00	$ 1.12
Net income attributable to common stockholders	$ 0.02	$ 0.62	$ 0.01	$ 0.99
OP Units [Member]
Denominator for earnings per share - basic and diluted:
Antidilutive securities	9,323,802	9,416,843	9,352,255	9,419,070
Convertible preferred stock [Member]
Denominator for earnings per share - basic and diluted:
Antidilutive securities	3,035,548	3,035,548	3,035,548	3,035,548
Stock options and unvested restricted stock [Member]
Denominator for earnings per share - basic and diluted:
Antidilutive securities	1,420,846	1,348,466	1,402,451	1,328,336
Series E Preferred Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Distributions to preferred stockholders	(931)	(931)	(1,862)	(1,862)
Series G Preferred Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Distributions to preferred stockholders	0	(909)	0	(2,286)
Noncontrolling Interest [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Income (loss) from continuing operations attributable to noncontrolling interest	(3)	(43)	(7)	(95)
RedeemableNoncontrollingInterest [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Income (loss) from continuing operations attributable to noncontrolling interest	$ (159)	$ 875		$ 806