DEBT - Senior Secured Notes (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Jul. 31, 2021	Dec. 31, 2020	Aug. 31, 2018
Line of Credit Facility [Line Items]
Loss on extinguishment of debt	$ 40,206	$ 0	$ 40,206	$ 0
7.50% Senior Secured Notes
Line of Credit Facility [Line Items]
Stated interest rate	7.50%		7.50%
8.25% Senior Secured Notes
Line of Credit Facility [Line Items]
Stated interest rate	8.25%		8.25%
Senior Notes
Line of Credit Facility [Line Items]
Stated interest rate					7.50%
Senior Notes | 7.50% Senior Secured Notes
Line of Credit Facility [Line Items]
Stated interest rate	7.50%		7.50%		7.50%
Debt instrument, face amount					$ 750,000
Capitalized financing costs					$ 15,500
Loss on extinguishment of debt	$ 40,200
Senior Notes | 8.25% Senior Secured Notes
Line of Credit Facility [Line Items]
Stated interest rate	8.25%		8.25%			8.25%	8.25%
Debt instrument, face amount							$ 690,000
Capitalized financing costs							$ 13,900