CAPITAL STRUCTURE (UNITED DOMINION REALTY, L.P.) - Units Rollforward (Details) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Capital structure
Balance	183,637	183,351	183,279
Vesting of LTIP Units	427	286	72
Balance	184,064	183,637	183,351
UDR, Inc.
Capital structure
Balance	174,100
Balance	176,100	174,100
Non-affiliated Partners
Capital structure
Balance	7,900
Class A Limited Partner | UDR, Inc.
Capital structure
Balance	121	121	121
Balance	121	121	121
Non-affiliated Partners | Class A Limited Partner
Capital structure
Balance	1,752	1,752	1,752
Balance	1,752	1,752	1,752
Limited Partner
Capital structure
Balance	7,636	7,361	7,297
Vesting of LTIP Units	427	286	72
OP redemptions for UDR stock	(1,969)	(11)	(8)
Balance	6,094	7,636	7,361
Limited Partner | UDR, Inc.
Capital structure
Balance	174,017	174,006	173,998
OP redemptions for UDR stock	1,969	11	8
Balance	175,986	174,017	174,006
General Partner | UDR, Inc.
Capital structure
Balance	111	111	111
Balance	111	111	111