INDEBTEDNESS - Estimated Fair Values of Debt Obligations (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Debt Instrument, Changes In Long-Term Debt [Roll Forward]
Repayments of debt principal	$ (2,075)	$ (4,112)
Issuance of Second Lien Notes as of August 6, 2019	981,050	$ 1,000
Senior Notes
Debt Instrument [Line Items]
Total debt instruments	1,266,398
Debt Instrument, Changes In Long-Term Debt [Roll Forward]
Total debt instruments, end of period	1,266,398
Senior Notes | First Lien Term Loan
Debt Instrument [Line Items]
Total debt instruments	892,729
Debt Instrument, Changes In Long-Term Debt [Roll Forward]
Total debt instruments, end of period	892,729
Senior Notes | Second Lien Notes
Debt Instrument [Line Items]
Total debt instruments	373,669
Debt Instrument, Changes In Long-Term Debt [Roll Forward]
Total debt instruments, end of period	373,669
Senior Notes | Markets for Identical Item (Level 1)
Debt Instrument [Line Items]
Total debt instruments	0
Debt Instrument, Changes In Long-Term Debt [Roll Forward]
Total debt instruments, end of period	0
Senior Notes | Markets for Identical Item (Level 1) | First Lien Term Loan
Debt Instrument [Line Items]
Total debt instruments	0
Debt Instrument, Changes In Long-Term Debt [Roll Forward]
Total debt instruments, end of period	0
Senior Notes | Markets for Identical Item (Level 1) | Second Lien Notes
Debt Instrument [Line Items]
Total debt instruments	0
Debt Instrument, Changes In Long-Term Debt [Roll Forward]
Total debt instruments, end of period	0
Senior Notes | Significant Other Observable Inputs (Level 2)
Debt Instrument [Line Items]
Total debt instruments	922,688
Debt Instrument, Changes In Long-Term Debt [Roll Forward]
Total debt instruments, end of period	922,688
Senior Notes | Significant Other Observable Inputs (Level 2) | First Lien Term Loan
Debt Instrument [Line Items]
Total debt instruments	922,688
Debt Instrument, Changes In Long-Term Debt [Roll Forward]
Total debt instruments, end of period	922,688
Senior Notes | Significant Other Observable Inputs (Level 2) | Second Lien Notes
Debt Instrument [Line Items]
Total debt instruments	0
Debt Instrument, Changes In Long-Term Debt [Roll Forward]
Total debt instruments, end of period	0
Senior Notes | Significant Unobservable Inputs (Level 3)
Debt Instrument [Line Items]
Total debt instruments	551,882
Debt Instrument, Changes In Long-Term Debt [Roll Forward]
Total debt instruments, beginning of period	551,882
Change in fair value	(369)
Repayments of debt principal	(2,075)
Retirements of Previous Term Loans	(549,438)
Total debt instruments, end of period	394,653
Senior Notes | Significant Unobservable Inputs (Level 3) | First Lien Term Loan
Debt Instrument [Line Items]
Total debt instruments	0
Debt Instrument, Changes In Long-Term Debt [Roll Forward]
Total debt instruments, end of period	0
Senior Notes | Significant Unobservable Inputs (Level 3) | Second Lien Notes
Debt Instrument [Line Items]
Total debt instruments	394,653
Debt Instrument, Changes In Long-Term Debt [Roll Forward]
Change in fair value	6,653
Issuance of Second Lien Notes as of August 6, 2019	388,000
Total debt instruments, end of period	$ 394,653