DEBT - Senior Secured Notes (Details) - USD ($)		12 Months Ended
	Apr. 02, 2015	Dec. 31, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Payment for Debt Extinguishment or Debt Prepayment Cost		$ 264,731,000	$ 30,000,000
(Loss) Gain on debt extinguishment		(56,113,000)	26,385,000
Carrying Value [Abstract]
Total principal amount		84,118,000	427,500,000
Unamortized discount of the liability component		(16,000)	(70,699,000)
Unamortized debt issuance costs		0	(5,543,000)
Carrying value		84,102,000	351,258,000
Interest Expense [Abstract]
Amortization of debt discount and debt issuance costs		5,680,000	23,764,000
Interest expense		6,870,000
Senior Notes
Debt Instrument [Line Items]
Par value of debt	$ 575,000,000.0
Proceeds from the issuance of debt	$ 562,000,000.0
Repurchased aggregate principal amount		162,500,000
Payment for Debt Extinguishment or Debt Prepayment Cost		4,900,000
Payment debt exit fees		4,400,000
(Loss) Gain on debt extinguishment		(8,233,000)	0
Write off of unamortized debt discount and debt issuance costs		3,300,000
Carrying Value [Abstract]
Total principal amount		0	162,500,000
Unamortized discount of the liability component			(4,035,000)
Unamortized debt issuance costs			(2,022,000)
Carrying value			156,443,000
Interest Expense [Abstract]
Stated coupon interest		1,648,000	25,559,000
Amortization of debt discount and debt issuance costs		2,699,000	5,783,000
Interest expense		$ 4,347,000	$ 31,342,000
Senior Notes | Three month LIBOR
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	9.75%
Interest rate through third anniversary	11.95%
Interest rate after third anniversary	12.95%
Senior Notes | Three month LIBOR | Minimum
Debt Instrument [Line Items]
Interest rate	1.00%
Senior Notes | NUCYNTA
Debt Instrument [Line Items]
Proceeds from the issuance of debt	$ 550,000,000.0