FAIR VALUE MEASUREMENTS - Summary of Fair Value Level 3 Debt Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Term loan	$ 429,143	$ 298,500
Revolving credit facility	0	5,000
Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Term loan	428,071	301,485
Revolving credit facility	$ 0	$ 5,050