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, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Accounting Policies [Abstract]
Total interest costs incurred			$ 40,592	$ 40,602
Interest capitalized			380	1,215
Interest expense	$ 13,734	$ 12,879	40,212	39,387
Cash paid for interest, net of amounts capitalized			39,375	39,674
Cash paid for income taxes			601	337
Accounts payable and accrued liabilities for construction in progress			16,025	14,677
Accrued leasing commissions			2,939	2,560
Reduction to capital for prepaid offering costs			$ 0	$ 236