REAL ESTATE OWNED (UNITED DOMINION REALTY, L.P.) - Summary (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Real estate owned
Land	$ 2,164,032	$ 1,849,799
Depreciable property - held and used:
Land Improvements	224,964	213,224
Building, improvements, and furniture, fixtures and equipment	10,102,758	8,133,136
Under development:
Real estate under development (net of accumulated depreciation of $23 and $0, respectively)	69,754
Real estate owned	12,602,101	10,196,159
Accumulated depreciation	(4,131,353)	(3,654,160)
Total real estate owned, net of accumulated depreciation	8,470,748	6,541,999
United Dominion Realty L.P.
Real estate owned
Land	711,256	711,256
Depreciable property - held and used:
Land Improvements	96,864	92,000
Building, improvements, and furniture, fixtures and equipment	3,067,040	3,008,729
Under development:
Real estate owned	3,875,160	3,811,985
Accumulated depreciation	(1,796,568)	(1,658,161)
Total real estate owned, net of accumulated depreciation	$ 2,078,592	$ 2,153,824