CAPITAL STRUCTURE (UNITED DOMINION REALTY, L.P.) - Units Rollforward (Details)	9 Months Ended
	Sep. 30, 2020 shares
Capital structure
Balance	184,064,000
Vesting of LTIP Units	772,000
Balance	184,836,000
UDR, Inc.
Capital structure
Balance	176,100,000
Balance	176,100,000
Non-affiliated Partners
Capital structure
Balance	8.6
Class A Limited Partner | UDR, Inc.
Capital structure
Balance	100,000
Balance	100,000
Non-affiliated Partners | Class A Limited Partner
Capital structure
Balance	1,752,000
Balance	1,752,000
Limited Partner
Capital structure
Balance	6,094,000
Vesting of LTIP Units	772,000
OP redemptions for UDR stock	(3,000)
Balance	6,863,000
Limited Partner | UDR, Inc.
Capital structure
Balance	175,986,000
OP redemptions for UDR stock	3,000
Balance	175,989,000
Class A Limited Partner | UDR, Inc.
Capital structure
Balance	121,000
Balance	121,000
General Partner | UDR, Inc.
Capital structure
Balance	111,000
Balance	111,000