REAL ESTATE OWNED (UNITED DOMINION REALTY, L.P.) - Acquisitions and Dispositions (Details) $ in Millions	3 Months Ended
	Mar. 31, 2020 USD ($) item community state	Mar. 31, 2019 USD ($)
Real Estate Owned Disclosure
Number of communities owned (in communities) | community	150
Number of states in which there are owned and consolidated communities | state	13
Development costs excluding direct costs and capitalized interest	$ 6.9	$ 3.3
Number of apartments owned (in apartments homes) | item	47,579
Interest capitalized during period	$ 1.4	1.1
United Dominion Realty L.P.
Real Estate Owned Disclosure
Number of communities owned (in communities) | community	52
Number of states in which there are owned and consolidated communities | state	9
Development costs excluding direct costs and capitalized interest	$ 0.4
Number of apartments owned (in apartments homes) | item	16,434
United Dominion Realty L.P. | Maximum
Real Estate Owned Disclosure
Development costs excluding direct costs and capitalized interest		0.1
Interest capitalized during period	$ 0.1	$ 0.1