Consolidated Statements of Changes in Capital (UNITED DOMINION REALTY, L.P) (Unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2013
Increase (Decrease) in Partners' Capital [Roll Forward]
Other comprehensive income (loss)	$ 1,752	$ 3,597
United Dominion Reality L.P. [Member]
Increase (Decrease) in Partners' Capital [Roll Forward]
Balance, December 31, 2012		1,918,756
Distributions		(86,976)
OP Unit Redemptions for common shares of UDR	0
Net income		17,994
Other comprehensive income (loss)	540	1,368
Net change in amount due to/(from) General Partner		76,505
Balance, June 30, 2013	1,927,647	1,927,647
Accumulated Other Comprehensive Income (Loss) [Member] | United Dominion Reality L.P. [Member]
Increase (Decrease) in Partners' Capital [Roll Forward]
Balance, December 31, 2012		(5,369)
Other comprehensive income (loss)		1,368
Balance, June 30, 2013	(4,001)	(4,001)
Total Partner's Capital [Member] | United Dominion Reality L.P. [Member]
Increase (Decrease) in Partners' Capital [Roll Forward]
Balance, December 31, 2012		1,917,299
Distributions		(86,976)
Net income		17,882
Other comprehensive income (loss)		1,368
Balance, June 30, 2013	1,849,573	1,849,573
Receivable Due From General Partner [Member] | United Dominion Reality L.P. [Member]
Increase (Decrease) in Partners' Capital [Roll Forward]
Balance, December 31, 2012		(11,056)
Net change in amount due to/(from) General Partner		76,505
Balance, June 30, 2013	65,449	65,449
Noncontrolling Interest [Member] | United Dominion Reality L.P. [Member]
Increase (Decrease) in Partners' Capital [Roll Forward]
Balance, December 31, 2012		12,513
Net income		112
Balance, June 30, 2013	12,625	12,625
Class A Limited Partner [Member] | United Dominion Reality L.P. [Member]
Increase (Decrease) in Partners' Capital [Roll Forward]
Balance, December 31, 2012		41,656
Distributions		(1,164)
Adjustment to reflect limited partners' capital at redemption value		3,989
Net income		170
Balance, June 30, 2013	44,651	44,651
Limited Partners [Member] | United Dominion Reality L.P. [Member]
Increase (Decrease) in Partners' Capital [Roll Forward]
Balance, December 31, 2012		181,762
Distributions		(3,560)
OP Unit Redemptions for common shares of UDR		(1,711)
Adjustment to reflect limited partners' capital at redemption value		15,773
Net income		735
Balance, June 30, 2013	192,999	192,999
Limited Partner [Member] | United Dominion Reality L.P. [Member]
Increase (Decrease) in Partners' Capital [Roll Forward]
Balance, December 31, 2012		1,698,027
Distributions		(82,200)
OP Unit Redemptions for common shares of UDR		1,711
Adjustment to reflect limited partners' capital at redemption value		(19,762)
Net income		16,966
Balance, June 30, 2013	1,614,742	1,614,742
General Partner [Member] | United Dominion Reality L.P. [Member]
Increase (Decrease) in Partners' Capital [Roll Forward]
Balance, December 31, 2012		1,223
Distributions		(52)
Net income		11
Balance, June 30, 2013	1,182	1,182
Partnership Capital [Member] | United Dominion Reality L.P. [Member]
Increase (Decrease) in Partners' Capital [Roll Forward]
OP Unit Redemptions for common shares of UDR	0
Adjustment to reflect limited partners' capital at redemption value	$ 0