SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Supplement Disclosures Related to Consolidated Statements of Cash Flows (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Accounting Policies [Abstract]
Total interest costs incurred			$ 40,602	$ 41,009
Interest capitalized			1,215	1,153
Interest expense	$ 12,879	$ 13,873	39,387	39,856
Cash paid for interest, net of amounts capitalized			39,674	33,720
Cash paid for income taxes			337	296
Accounts payable and accrued liabilities for construction in progress			7,381	(3,019)
Accrued leasing commissions			865	1,410
Reduction to capital for prepaid offering costs			$ 236	$ 129