MORTGAGE DEBT - Mortgage Debt, Additional Information (Details)	12 Months Ended
	Dec. 31, 2019 property acquisition loan	Dec. 31, 2018
Debt Instrument [Line Items]
Number of acquisitions partially financed with mortgages | acquisition	4
Number of existing mortgages refinanced | loan	2
Number of properties that acquired supplemental financing | property	2
Mortgage debt [Member]
Debt Instrument [Line Items]
Weighted-average interest rate of investment debt	3.41%	3.40%
Percent of property level debt with fixed rate	76.00%	73.00%
Percent of property level debt with floating rate and interest caps	14.00%	17.00%
Percent of property level debt with floating rate, without interest caps	10.00%	10.00%