SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Loss on Debt Extinguishment (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2019	Dec. 31, 2018	May 31, 2018	Nov. 10, 2016	Nov. 04, 2015
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loss on debt extinguishment	$ 4,533
$400 Million Credit Facility | Secured Debt
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Face amount of term loan facility	400,000	$ 400,000	$ 400,000		$ 400,000
$98 Million Credit Facility | Line of Credit Facility
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Face amount of term loan facility	98,000	$ 98,000	$ 98,000			$ 98,000
$460 Million Credit Facility | Secured Debt
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Face amount of term loan facility	$ 460,000			$ 460,000