REAL ESTATE OWNED - Acquisition from UDR/MetLife joint venture (Details)	1 Months Ended			12 Months Ended
	Nov. 30, 2019 item	Nov. 30, 2019 community	Nov. 30, 2019 property	Dec. 31, 2019 home community item
Real estate properties
Number of land parcels | property			4
UDR/MetLife operating communities
Real estate properties
Number of communities acquired | community		10		10
Number of communities under development purchased | community		1		1
Number of land parcels	4		4	4
UDR/MetLife operating communities | Strata
Real estate properties
Number of apartment homes				163
UDR/MetLife operating communities | Crescent Fall Church
Real estate properties
Number of apartment homes				214
UDR/MetLife operating communities | Charles River Landing
Real estate properties
Number of apartment homes				350
UDR/MetLife operating communities | Lodge at Ames Pond
Real estate properties
Number of apartment homes				364
UDR/MetLife operating communities | Lenox Farms
Real estate properties
Number of apartment homes				338
UDR/MetLife operating communities | Towson Promenade
Real estate properties
Number of apartment homes				379
UDR/MetLife operating communities | Savoye
Real estate properties
Number of apartment homes				394
UDR/MetLife operating communities | Savoye 2
Real estate properties
Number of apartment homes				351
UDR/MetLife operating communities | Fiori on Vitruvian Park
Real estate properties
Number of apartment homes				391
UDR/MetLife operating communities | Vitruvian West
Real estate properties
Number of apartment homes				383
UDR/MetLife operating communities | Vitruvian West Phase 2
Real estate properties
Number of apartment homes				366