FINANCIAL INSTRUMENTS AND FAIR VALUE MEASUREMENTS - Carrying Value and Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Carrying Value
Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, net	$ (494,373)	$ (712,277)
Unamortized debt issuance costs	5,600	7,700
Fair Value
Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, net	$ (495,625)	$ (725,700)

Amount of unamortized debt discount (premium) and debt issuance costs.

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Name:	us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant