INCOME/(LOSS) PER SHARE (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019	Jul. 31, 2017
Antidilutive securities
Net income/(loss)	$ 62,096	$ 38,318	$ 67,636	$ 64,920
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
Distributions to preferred stockholders - Series E (Convertible)	(1,062)	(1,031)	(2,128)	(2,042)
Net income/(loss) attributable to common stockholders	$ 56,709	$ 34,588	$ 60,864	$ 58,080
Denominator for earnings per share - basic and diluted:
Weighted average common shares outstanding	294,970,000	282,215,000	294,850,000	279,769,000
Non-vested restricted stock awards	(260,000)	(255,000)	(266,000)	(275,000)
Denominator for basic income/(loss) per share	294,710,000	281,960,000	294,584,000	279,494,000
Incremental shares issuable from assumed conversion of unvested LTIP Units and unvested restricted stock	377,000	615,000	499,000	587,000
Denominator for diluted income/(loss) per share	295,087,000	282,575,000	295,083,000	280,081,000
Income/(loss) per weighted average common share - basic	$ 0.19	$ 0.12	$ 0.21	$ 0.21
Income/(loss) per weighted average common share - diluted	$ 0.19	$ 0.12	$ 0.21	$ 0.21
Number of shares authorized	350,000,000		350,000,000		350,000,000
Aggregate gross proceeds				$ 212,872
Proceeds from the issuance of common shares through public offering, net				212,872
Aggregate net proceeds from sales, after deducting related costs		$ 20,693		$ 212,872
OP/DownREIT Units
Antidilutive securities
Antidilutive securities	22,386,000	22,736,000	22,307,000	23,504,000
Convertible preferred stock
Antidilutive securities
Antidilutive securities	2,953,000	3,011,000	2,982,000	3,011,000
Unvested LTIP Units and unvested restricted stock
Antidilutive securities
Antidilutive securities	377,000	615,000	499,000	587,000
ATM
Denominator for earnings per share - basic and diluted:
Number of shares authorized						20,000,000.0
Shares of common stock available for future issuance	11,700,000		11,700,000
Forward Sales Agreement
Denominator for earnings per share - basic and diluted:
Number of shares authorized	2,100,000		2,100,000
Weighted average price per share			$ 49.56
Shares settled			0