BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Deferred Rent Receivable and Charges (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Accounting Policies [Abstract]
Deferred rent receivable	$ 20,734	$ 19,988
Deferred leasing costs, net of accumulated amortization of $7,987 and $7,438, respectively	8,162	9,443
Deferred leasing costs, accumulated amortization	7,987	7,438
Deferred offering costs	5,892	5,275
Other deferred costs	542	151
Deferred rent receivable and charges, net	$ 35,330	$ 34,857