BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Revenue (Details) - USD ($)	Mar. 31, 2016	Dec. 31, 2015
Deferred Rent Receivable and Charges
Deferred rent receivable	$ 59,936,000	$ 58,612,000
Deferred leasing costs, gross	62,782,000	59,225,000
Deferred leasing costs, accumulated amortization	22,198,000	20,612,000
Other deferred charges	$ 40,000	$ 0