LEASES (UNITED DOMINION REALTY, L.P.) - Lessee Expenses (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($)
Lessee operating leases
Contractual ground lease expense	$ 400
Variable ground lease expense	400
Operating lease right-of-use asset amortization	1,200
Operating lease liabilities amortization	800
LAND
Lessee operating leases
Contractual ground lease expense	8,272
Variable ground lease expense	664
Office Space
Lessee operating leases
Total lease expense	9,006
United Dominion Realty L.P.
Lessee operating leases
Contractual ground lease expense	300
Total lease expense	8,955
Operating lease right-of-use asset amortization	1,000
Operating lease liabilities amortization	700
Short term lease expense	0
United Dominion Realty L.P. | LAND
Lessee operating leases
Contractual ground lease expense	8,272
Variable ground lease expense	664
Total lease expense	8,936
United Dominion Realty L.P. | Equipment Leases
Lessee operating leases
Contractual ground lease expense	$ 19