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CONSOLIDATION AND BASIS OF PRESENTATION (Details) | 12 Months Ended |  |  |
--- | --- | --- | --- | ---
Dec. 31, 2019 home USD ($) community item shares | Dec. 31, 2018 shares | Dec. 31, 2017 shares | Dec. 31, 2016 shares
Consolidation And Basis Of Presentation |  |  |  |
Number of Real Estate Properties | community | 148 |  |  |
Number of Markets Operating Within | $ | 20 |  |  |
Number Of Apartment Homes Owned And Consolidated By Company | home | 47,010 |  |  |
Operating Partnership units outstanding related to limited partner | 184,064,000 | 183,637,000 | 183,351,000 | 183,279,000
Joint venture, number of completed or to be completed homes in communities | home | 5,268 |  |  |
Preferred equity investment,, number of apartment homes | home | 2,138 |  |  |
Operating Partnership outstanding units | 184,100,000 | 183,600,000 |  |
United Dominion Realty L.P. |  |  |  |
Consolidation And Basis Of Presentation |  |  |  |
Operating Partnership units outstanding related to limited partner | 176,200,000 | 174,200,000 |  |
Percentage of units outstanding in Partnership | 95.70% | 94.90% |  |
UDR Lighthouse DownREIT L.P. |  |  |  |
Consolidation And Basis Of Presentation |  |  |  |
General Partners' ownership (as a percent) |  | 53.20% |  |
Operating Partnership outstanding units | 13,500,000 |  |  |
Percentage of units outstanding in Partnership | 41.70% |  |  |
UDR Lighthouse DownREIT L.P. |  |  |  |
Consolidation And Basis Of Presentation |  |  |  |
Operating Partnership outstanding units | 32,400,000 | 13,500,000 |  |
Percentage of units outstanding in Partnership |  | 41.60% |  |
Non-affiliated Partners |  |  |  |
Consolidation And Basis Of Presentation |  |  |  |
Operating Partnership units outstanding related to limited partner | 7,900,000 |  |  |
Operating Partnership outstanding units | 14,000,000.0 | 9,400,000 |  |
Percentage of units outstanding in Partnership | 4.30% | 5.10% |  |
Non-affiliated Partners | United Dominion Realty L.P. |  |  |  |
Consolidation And Basis Of Presentation |  |  |  |
Operating Partnership units outstanding related to limited partner | 7,900,000 |  |  |
Operating Partnership outstanding units | 7,900,000 | 9,400,000 |  |
Percentage of units outstanding in Partnership | 4.30% | 5.10% |  |
Non-affiliated Partners | UDR Lighthouse DownREIT L.P. |  |  |  |
Consolidation And Basis Of Presentation |  |  |  |
Operating Partnership outstanding units |  | 15,200,000 |  |
Percentage of units outstanding in Partnership | 43.20% | 46.80% |  |
UDR, Inc. |  |  |  |
Consolidation And Basis Of Presentation |  |  |  |
Operating Partnership units outstanding related to limited partner | 176,100,000 | 174,100,000 |  |
General Partners' ownership (as a percent) | 56.80% |  |  |
Operating Partnership outstanding units | 18,400,000 | 17,200,000 |  |
Percentage of units outstanding in Partnership | 95.70% | 94.90% |  |
UDR, Inc. | United Dominion Realty L.P. |  |  |  |
Consolidation And Basis Of Presentation |  |  |  |
Operating Partnership units outstanding related to limited partner | 176,100,000 | 174,100,000 |  |
General Partners' ownership (as a percent) | 95.70% | 94.90% |  |
Operating Partnership outstanding units | 176,200,000 | 174,200,000 |  |
Percentage of units outstanding in Partnership | 95.70% | 94.80% |  |
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 | home | 16,434 |  |  |
Operating Partnership units outstanding related to limited partner | 183,952,659 | 183,525,660 |  |
Operating Partnership outstanding units | 184,100,000 | 183,600,000 |  |

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