REPORTABLE SEGMENTS (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020 USD ($) home	Jun. 30, 2019 USD ($) home	Jun. 30, 2020 USD ($) segment home	Jun. 30, 2019 USD ($) home	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Segments
Same store communities | home	39,020	39,020	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	$ 305,982	$ 278,463	$ 626,075	$ 546,385
Reconciling items:
Joint venture management and other fees	$ 1,274	$ 2,845	$ 2,662	$ 5,596
Type of revenue	udr:ManagementAndOtherFeesMember	udr:ManagementAndOtherFeesMember	udr:ManagementAndOtherFeesMember	udr:ManagementAndOtherFeesMember
Property management	$ (8,797)	$ (8,006)	$ (18,000)	$ (15,709)
Other operating expenses	(6,100)	(2,735)	(11,066)	(8,381)
Real estate depreciation and amortization	(155,056)	(117,934)	(310,532)	(230,402)
General and administrative	(10,971)	(12,338)	(25,949)	(24,805)
Casualty-related (charges)/recoveries, net	(102)	(246)	(1,353)	(246)
Other depreciation and amortization	(2,027)	(1,678)	(4,052)	(3,334)
Gain/(loss) on sale of real estate owned	61,303	5,282	61,303	5,282
Income/(loss) from unconsolidated entities	8,021	6,625	11,388	6,674
Interest expense	(38,597)	(34,417)	(77,914)	(67,959)
Interest and other income/(expense), net	2,421	1,310	5,121	11,123
Tax (provision)/benefit, net	(1,526)	(125)	(1,690)	(2,337)
Net (income)/loss attributable to redeemable noncontrolling interests in the Operating Partnership and DownREIT Partnership	(4,291)	(2,652)	(4,604)	(4,709)
Net (income)/loss attributable to noncontrolling interests	(34)	(47)	(40)	(89)
Net income/(loss) attributable to UDR, Inc.	57,771	35,619	62,992	60,122
Reportable apartment home segment assets:
Total segment assets	12,775,639		12,775,639		$ 12,602,101
Accumulated depreciation	(4,372,524)		(4,372,524)		(4,131,353)
Total real estate owned, net of accumulated depreciation	8,403,115		8,403,115		8,470,748
Reconciling items:
Cash and cash equivalents	833	981	833	981	8,106	$ 185,216
Restricted cash	22,043	23,042	22,043	23,042	25,185	$ 23,675
Notes receivable, net	155,956		155,956		153,650
Investment in and advances to unconsolidated joint ventures, net	598,058		598,058		588,262
Operating lease right-of-use assets	202,586		202,586		204,225
Other assets	181,880		181,880		186,296
Total consolidated assets	9,564,471		9,564,471		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	101,551	104,196	200,750	199,495
Other revenue	2,842	3,047	5,543	6,045
Rental income	104,393	107,243	206,293	205,540
Reportable apartment home segment NOI	78,533	81,724	155,876	156,324
Reportable apartment home segment assets:
Total segment assets	3,889,925		3,889,925		3,874,027
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	54,803	54,905	110,889	109,205
Other revenue	1,429	1,727	3,001	3,729
Rental income	56,232	56,632	113,890	112,934
Reportable apartment home segment NOI	39,102	40,045	79,479	79,225
Reportable apartment home segment assets:
Total segment assets	2,363,674		2,363,674		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	29,717	32,225	58,774	60,490
Other revenue	761	789	1,235	1,396
Rental income	30,478	33,014	60,009	61,886
Reportable apartment home segment NOI	19,629	22,943	38,734	42,453
Reportable apartment home segment assets:
Total segment assets	1,635,118		1,635,118		1,632,980
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	32,715	31,844	61,433	59,565
Other revenue	1,226	1,719	2,593	3,431
Rental income	33,941	33,563	64,026	62,996
Reportable apartment home segment NOI	22,801	23,322	44,257	44,169
Reportable apartment home segment assets:
Total segment assets	913,257		913,257		903,878
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	16,391	16,294	33,017	32,370
Other revenue	515	678	1,105	1,443
Rental income	16,906	16,972	34,122	33,813
Reportable apartment home segment NOI	10,467	10,444	21,523	20,772
Reportable apartment home segment assets:
Total segment assets	605,801		605,801		600,349
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	62,404	30,523	144,340	67,763
Other revenue	1,628	516	3,395	1,453
Rental income	64,032	31,039	147,735	69,216
Reportable apartment home segment NOI	41,721	21,257	97,849	46,475
Reportable apartment home segment assets:
Total segment assets	3,367,864		3,367,864		$ 3,240,526
Total Communities
Summary of rental income and NOI for UDRs reportable segments and reconciliation of NOI to loss from continuing operations
Lease revenue	297,581	269,987	609,203	528,888
Other revenue	8,401	8,476	16,872	17,497
Rental income	305,982	278,463	626,075	546,385
Reportable apartment home segment NOI	$ 212,253	$ 199,735	$ 437,718	$ 389,418
Taxable REIT Subsidiaries
Reportable Segments
Management fee (as a percent)			2.875%