CONSOLIDATED STATEMENT OF CHANGES IN CAPITAL (UNITED DOMINION REALTY, L.P.) - USD ($) $ in Thousands	3 Months Ended				12 Months Ended
	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Increase (Decrease) in Partners' Capital [Roll Forward]
Net income/(loss)	$ 105,237	$ 26,602	$ 89,615	$ 89,225	$ 199,579	$ 221,542	$ 132,655
Advances (to)/from General Partner
Increase (Decrease) in Partners' Capital [Roll Forward]
Beginning Balance				397,899		397,899	19,659
Conversion of Advances (to)/from the General Partner to notes payable						(257,204)
Net change in advances (to)/from the General Partner						(140,695)	378,240
Ending Balance							397,899
Accumulated Other Comprehensive Income/(Loss), net
Increase (Decrease) in Partners' Capital [Roll Forward]
Beginning Balance							(113)
Unrealized gain/(loss) on derivative financial investments							113
United Dominion Realty L.P.
Increase (Decrease) in Partners' Capital [Roll Forward]
Beginning Balance		1,485,889		1,875,130	1,485,889	1,875,130	1,618,499
Net income/(loss)	24,568	24,334	86,324	91,845	103,995	231,485	107,855
Distributions					(252,818)	(237,827)	(228,090)
Long Term Incentive Plan Unit grants					27,066	15,839	7,763
Unrealized gain/(loss) on derivative financial investments							107
Conversion of Advances (to)/from the General Partner to notes payable						(257,204)
Net change in advances (to)/from the General Partner						(141,534)	368,996
Net contributions/(distributions) to/(from) noncontrolling interests					1,754
Ending Balance	1,365,886		1,485,889		1,365,886	1,485,889	1,875,130
United Dominion Realty L.P. | Total Partner's Capital
Increase (Decrease) in Partners' Capital [Roll Forward]
Beginning Balance		1,472,070		1,464,295	1,472,070	1,464,295	1,578,202
Net income/(loss)					102,163	229,763	106,307
Distributions					(252,818)	(237,827)	(228,090)
Long Term Incentive Plan Unit grants					27,066	15,839	7,763
Unrealized gain/(loss) on derivative financial investments							113
Ending Balance	1,348,481		1,472,070		1,348,481	1,472,070	1,464,295
United Dominion Realty L.P. | Noncontrolling Interests
Increase (Decrease) in Partners' Capital [Roll Forward]
Beginning Balance		13,819		12,936	13,819	12,936	20,638
Net income/(loss)					1,832	1,722	1,548
Unrealized gain/(loss) on derivative financial investments							(6)
Net change in advances (to)/from the General Partner						(839)	(9,244)
Net contributions/(distributions) to/(from) noncontrolling interests					1,754
Ending Balance	17,405		13,819		17,405	13,819	12,936
United Dominion Realty L.P. | Class A Limited Partner
Increase (Decrease) in Partners' Capital [Roll Forward]
Beginning Balance		69,401		67,474	69,401	67,474	63,901
Net income/(loss)					971	2,221	1,015
Distributions					(2,396)	(2,328)	(2,328)
Adjustment to reflect limited partners' capital at redemption value					13,827	2,034	4,886
Ending Balance	81,803		69,401		81,803	69,401	67,474
United Dominion Realty L.P. | Limited Partners and LTIP Units
Increase (Decrease) in Partners' Capital [Roll Forward]
Beginning Balance		302,545		283,568	302,545	283,568	269,928
Net income/(loss)					3,404	9,977	4,270
Distributions					(9,063)	(10,718)	(9,704)
OP Unit redemptions for common shares of UDR					(79,010)	(416)	(288)
Adjustment to reflect limited partners' capital at redemption value					39,638	4,295	11,599
Long Term Incentive Plan Unit grants					27,066	15,839	7,763
Ending Balance	284,580		302,545		284,580	302,545	283,568
United Dominion Realty L.P. | Limited Partner
Increase (Decrease) in Partners' Capital [Roll Forward]
Beginning Balance		1,099,174		1,112,298	1,099,174	1,112,298	1,243,460
Net income/(loss)					97,727	217,426	100,957
Distributions					(241,207)	(224,637)	(215,922)
OP Unit redemptions for common shares of UDR					79,010	416	288
Adjustment to reflect limited partners' capital at redemption value					(53,465)	(6,329)	(16,485)
Ending Balance	981,239		1,099,174		981,239	1,099,174	1,112,298
United Dominion Realty L.P. | General Partner
Increase (Decrease) in Partners' Capital [Roll Forward]
Beginning Balance		$ 950		$ 955	950	955	1,026
Net income/(loss)					61	139	65
Distributions					(152)	(144)	(136)
Ending Balance	$ 859		$ 950		$ 859	$ 950	$ 955