BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Estimated Fair Value and Outstanding Balances of Borrowings (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Fair Value | Level 2 | Term Loan
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	$ 815,985	$ 826,099
Fair Value | Level 1 | Senior unsecured notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	377,813	372,656
Outstanding Balance | Level 2 | Term Loan
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	809,750	815,900
Outstanding Balance | Level 1 | Senior unsecured notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	$ 375,000	$ 375,000