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JOINT VENTURES AND PARTNERSHIPS - Commitments (Details) $ in Thousands	1 Months Ended				12 Months Ended
	Jan. 31, 2026 USD ($)	Dec. 31, 2025 USD ($)	Sep. 30, 2025 USD ($)	Jun. 30, 2025 USD ($)	Dec. 31, 2025 USD ($)	Dec. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)	Aug. 31, 2025 USD ($) home	Jul. 31, 2025 USD ($) home	Apr. 30, 2025 USD ($) home
Joint Ventures
Investment in unconsolidated entities		$ 879,735			$ 879,735	$ 912,183
Deferred fees from the sale of properties		8,400			8,400	7,600
Joint venture management and other fees					$ 11,361	$ 8,317	$ 6,843
Type of revenue					udr:ManagementAndOtherFeesMember	udr:ManagementAndOtherFeesMember	udr:ManagementAndOtherFeesMember
Equity method investment amount sold						$ 81,123
Management Services
Joint Ventures
Joint venture management and other fees					$ 11,400	8,300	$ 6,800
13th and Market Properties LLC \| Accounts payable and Accrued Liabilities
Joint Ventures
Investment in unconsolidated entities		(6,800)			(6,800)	(5,300)
Daly City, CA
Joint Ventures
Number of apartment homes \| home										256
Equity investment										$ 13,000
Preferred return (as a percent)										12.00%
Preferred Equity Investments
Joint Ventures
Proceeds from sale of real estate			$ 32,200	$ 54,800
Orlando, Florida
Joint Ventures
Number of apartment homes \| home									350
Equity investment									$ 23,800
Preferred return (as a percent)									11.25%
Yorba Linda, California
Joint Ventures
Number of apartment homes \| home								400
Equity investment								$ 35,800
Preferred return (as a percent)								10.00%
Operating Community \| Preferred Equity Investments
Joint Ventures
Investment in unconsolidated entities		$ 373,231			$ 373,231	$ 299,846
Number of apartment homes		6,766			6,766
Preferred return (as a percent)		9.70%			9.70%
Proceeds from sale of real estate		$ 10,300
Operating Community \| Preferred Equity Investments \| Subsequent Event
Joint Ventures
Proceeds from sale of real estate	$ 52,900