FINANCIAL INSTRUMENTS - Carrying Value and Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Carrying Value
Balance Sheet Grouping, Financial Statement Captions
Long-term debt, net	$ (3,843,244)	$ (3,840,930)
Unamortized original issue discount and debt issuance costs	49,300	51,600
Fair Value
Balance Sheet Grouping, Financial Statement Captions
Long-term debt, net	(5,894,051)	(6,267,976)
Fair Value | 2022 Exchangeable Notes
Balance Sheet Grouping, Financial Statement Captions
Long-term debt, net	(1,617,800)	(1,780,300)
Fair Value | 2026 Exchangeable Notes
Balance Sheet Grouping, Financial Statement Captions
Long-term debt, net	(970,600)	(1,052,100)
Fair Value | 2030 Exchangeable Notes
Balance Sheet Grouping, Financial Statement Captions
Long-term debt, net	$ (1,031,200)	$ (1,113,900)