BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Deferred Rent Receivable and Charges (Details) - USD ($)	Jun. 30, 2016	Dec. 31, 2015
Deferred Rent Receivable and Charges
Deferred rent receivable	$ 60,667,000	$ 58,612,000
Deferred leasing costs, gross	64,678,000	59,225,000
Deferred leasing costs, accumulated amortization	23,587,000	20,612,000
Deferred offering costs	$ 1,346,000	$ 0