LEASES (UNITED DOMINION REALTY, L.P.) - Lessee Expenses (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2019
Lessee operating leases
Contractual lease expense	$ 100	$ 200
Variable lease expense	100	200
Total lease expense	2,301	4,598
Operating lease right-of-use asset amortization		400
Operating lease liabilities amortization		200
Ground Leases
Lessee operating leases
Contractual lease expense	2,139	4,278
Variable lease expense	143	282
United Dominion Reality L.P.
Lessee operating leases
Contractual lease expense	100	200
Operating lease right-of-use asset amortization		400
Operating lease liabilities amortization		200
United Dominion Reality L.P. | Ground Leases
Lessee operating leases
Contractual lease expense	2,139	4,278
Variable lease expense	143	282
Total lease expense	$ 2,282	$ 4,560