BASIS OF PRESENTATION (Details)	Mar. 31, 2020 item community shares	Dec. 31, 2019 shares
Consolidation And Basis Of Presentation
Number of Real Estate Properties | community	150
Number Of Apartment Homes Owned And Consolidated By Company | item	47,579
Operating Partnership units outstanding related to limited partner	184,836,000	184,064,000
Operating Partnership outstanding units	184.8
United Dominion Realty L.P.
Consolidation And Basis Of Presentation
Operating Partnership units outstanding related to limited partner	176.2
General Partnership units outstanding	100,000
General Partners' ownership (as a percent)	95.30%
UDR Lighthouse DownREIT L.P.
Consolidation And Basis Of Presentation
Operating Partnership outstanding units	13.5
Percentage of units outstanding in Partnership	41.60%
UDR Lighthouse DownREIT L.P.
Consolidation And Basis Of Presentation
Operating Partnership outstanding units	32.4
Non-affiliated Partners
Consolidation And Basis Of Presentation
Operating Partnership units outstanding related to limited partner	8.6
Operating Partnership outstanding units	13.8
Percentage of units outstanding in Partnership	4.70%
Non-affiliated Partners | United Dominion Realty L.P.
Consolidation And Basis Of Presentation
Operating Partnership units outstanding related to limited partner	8.6
Operating Partnership outstanding units		7.9
Percentage of units outstanding in Partnership	4.70%	4.30%
Non-affiliated Partners | UDR Lighthouse DownREIT L.P.
Consolidation And Basis Of Presentation
Percentage of units outstanding in Partnership	42.60%
UDR, Inc.
Consolidation And Basis Of Presentation
Operating Partnership units outstanding related to limited partner	176,100,000	176,100,000
General Partners' ownership (as a percent)	57.40%
Operating Partnership outstanding units	18.6
Percentage of units outstanding in Partnership	95.30%	95.70%
UDR, Inc. | United Dominion Realty L.P.
Consolidation And Basis Of Presentation
General Partnership units outstanding	176.2
General Partners' ownership (as a percent)	95.30%
Operating Partnership outstanding units		176,200,000
Percentage of units outstanding in Partnership		95.70%
United Dominion Realty L.P.
Consolidation And Basis Of Presentation
Number of Real Estate Properties | community	52
Number of Markets Operating Within | item	15
Number Of Apartment Homes Owned And Consolidated By Company | item	16,434
Operating Partnership units outstanding related to limited partner	184,724,677	183,952,659
General Partnership units outstanding	110,883	110,883
Operating Partnership outstanding units	184,800,000	184,100,000