REPORTABLE SEGMENTS (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2020 USD ($)	Mar. 31, 2020 USD ($) segment	Mar. 31, 2020 USD ($)	Mar. 31, 2020 USD ($)	Mar. 31, 2020 USD ($) item	Mar. 31, 2020 USD ($) home	Mar. 31, 2019 USD ($) item	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Segments
Same store communities					37,910	37,910	37,910
Reportable Segments
Number of reportable segments | segment		2
Condition for Community considered to have stabilized occupancy	90%
Time to maintain percent occupancy to be considered a community	3 months
Practical expedient, single lease component	true
Summary of rental income and NOI for UDRs reportable segments and reconciliation of NOI to loss from continuing operations
Rental income				$ 320,093			$ 267,922
Reconciling items:
Joint venture management and other fees				1,388			$ 2,751
Type of revenue	udr:ManagementAndOtherFeesMember						udr:ManagementAndOtherFeesMember
Property management				(9,203)			$ (7,703)
Other operating expenses				(4,966)			(5,646)
Real estate depreciation and amortization				(155,476)			(112,468)
General and administrative				(14,978)			(12,467)
Casualty-related (charges)/recoveries, net				(1,251)
Other depreciation and amortization				(2,025)			(1,656)
Income/(loss) from unconsolidated entities				3,367			49
Interest expense				(39,317)			(33,542)
Interest and other income/(expense), net				2,700			9,813
Tax (provision)/benefit, net				(164)			(2,212)
Net (income)/loss attributable to redeemable noncontrolling interests in the Operating Partnership and DownREIT Partnership				(313)			(2,057)
Net (income)/loss attributable to noncontrolling interests				(6)			(42)
Net income/(loss) attributable to UDR, Inc.				5,221			24,503
Reportable apartment home segment assets:
Total segment assets	$ 12,817,998	$ 12,817,998	$ 12,817,998	12,817,998	$ 12,817,998	$ 12,817,998		$ 12,602,101
Accumulated depreciation	(4,272,471)	(4,272,471)	(4,272,471)	(4,272,471)	(4,272,471)	(4,272,471)		(4,131,353)
Total real estate owned, net of accumulated depreciation	8,545,527	8,545,527	8,545,527	8,545,527	8,545,527	8,545,527		8,470,748
Reconciling items:
Cash and cash equivalents	980	980	980	980	980	980	1,043	8,106	$ 185,216
Restricted cash	21,949	21,949	21,949	21,949	21,949	21,949	23,111	25,185	$ 23,675
Notes receivable, net	151,543	151,543	151,543	151,543	151,543	151,543		153,650
Investment in and advances to unconsolidated joint ventures, net	588,395	588,395	588,395	588,395	588,395	588,395		588,262
Operating lease right-of-use assets	203,410	203,410	203,410	203,410	203,410	203,410		204,225
Other assets	179,301	179,301	179,301	179,301	179,301	179,301		186,296
Total consolidated assets	9,691,105	9,691,105	9,691,105	9,691,105	9,691,105	9,691,105		9,636,472
Same Store Communities West Region
Summary of rental income and NOI for UDRs reportable segments and reconciliation of NOI to loss from continuing operations
Lease revenue				102,616			98,633
Other revenue				2,774			3,076
Rental income				105,390			101,709
Reportable apartment home segment NOI				79,823			76,984
Reportable apartment home segment assets:
Total segment assets	3,704,480	3,704,480	3,704,480	3,704,480	3,704,480	3,704,480		3,696,544
Same Store Communities Mid-Atlantic Region
Summary of rental income and NOI for UDRs reportable segments and reconciliation of NOI to loss from continuing operations
Lease revenue				56,085			54,300
Other revenue				1,573			2,002
Rental income				57,658			56,302
Reportable apartment home segment NOI				40,377			39,179
Reportable apartment home segment assets:
Total segment assets	2,356,688	2,356,688	2,356,688	2,356,688	2,356,688	2,356,688		2,350,341
Same Store Communities Northeast Region
Summary of rental income and NOI for UDRs reportable segments and reconciliation of NOI to loss from continuing operations
Lease revenue				30,942			30,193
Other revenue				501			629
Rental income				31,443			30,822
Reportable apartment home segment NOI				20,614			20,977
Reportable apartment home segment assets:
Total segment assets	1,501,767	1,501,767	1,501,767	1,501,767	1,501,767	1,501,767		1,500,597
Same Store Communities Southeast Region
Summary of rental income and NOI for UDRs reportable segments and reconciliation of NOI to loss from continuing operations
Lease revenue				30,677			29,531
Other revenue				1,429			1,790
Rental income				32,106			31,321
Reportable apartment home segment NOI				22,617			22,010
Reportable apartment home segment assets:
Total segment assets	810,984	810,984	810,984	810,984	810,984	810,984		806,830
Same Store Communities Southwest Region
Summary of rental income and NOI for UDRs reportable segments and reconciliation of NOI to loss from continuing operations
Lease revenue				16,626			16,077
Other revenue				590			763
Rental income				17,216			16,840
Reportable apartment home segment NOI				11,056			10,328
Reportable apartment home segment assets:
Total segment assets	603,082	603,082	603,082	603,082	603,082	603,082		600,350
Non-Mature communities/Other
Summary of rental income and NOI for UDRs reportable segments and reconciliation of NOI to loss from continuing operations
Lease revenue				74,676			30,169
Other revenue				1,604			759
Rental income				76,280			30,928
Reportable apartment home segment NOI				50,978			20,205
Reportable apartment home segment assets:
Total segment assets	$ 3,840,997	$ 3,840,997	$ 3,840,997	3,840,997	$ 3,840,997	$ 3,840,997		$ 3,647,439
Total Communities
Summary of rental income and NOI for UDRs reportable segments and reconciliation of NOI to loss from continuing operations
Lease revenue				311,622			258,903
Other revenue				8,471			9,019
Rental income				320,093			267,922
Reportable apartment home segment NOI				$ 225,465			$ 189,683
Taxable REIT Subsidiaries
Reportable Segments
Management fee (as a percent)			2.875%