INCOME/(LOSS) PER SHARE (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019	Jul. 31, 2017
Antidilutive securities
Net income/(loss)	$ 5,540	$ 26,602
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
Distributions to preferred stockholders - Series E (Convertible)	(1,066)	(1,011)
Net income/(loss) attributable to common stockholders	$ 4,155	$ 23,492
Denominator for earnings per share - basic and diluted:
Weighted average common shares outstanding	294,731,000	277,297,000
Non-vested restricted stock awards	(274,000)	(295,000)
Denominator for basic income/(loss) per share	294,457,000	277,002,000
Incremental shares issuable from assumed conversion of unvested LTIP Units and unvested restricted stock	703,000	555,000
Denominator for diluted income/(loss) per share	295,160,000	277,557,000
Income/(loss) per weighted average common share - basic	$ 0.01	$ 0.08
Income/(loss) per weighted average common share - diluted	$ 0.01	$ 0.08
Number of shares authorized	350,000,000		350,000,000
Aggregate gross proceeds		$ 192,179
Proceeds from the issuance of common shares through public offering, net		192,179
Aggregate net proceeds from sales, after deducting related costs		$ 192,179
OP/DownREIT Units
Antidilutive securities
Antidilutive securities	22,228,000	24,280,000
Convertible preferred stock
Antidilutive securities
Antidilutive securities	3,011,000	3,011,000
Unvested LTIP Units and unvested restricted stock
Antidilutive securities
Antidilutive securities	703,000	555,000
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
Forward Sales Agreement
Denominator for earnings per share - basic and diluted:
Number of shares authorized	2,100,000
Weighted average price per share	$ 49.56
Forward purchase agreement	0
Shares settled	0