INTANGIBLE ASSETS - Schedule of Gross Carrying Amounts and Net Book Value Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 1,098,588	$ 1,098,588
Accumulated Amortization	(508,263)	(406,489)
Impairment	(189,790)	0	$ 0
Total	$ 400,535	692,099
Product rights | NUCYNTA
Finite-Lived Intangible Assets [Line Items]
Remaining Useful Life (In years)	6 years
Gross Carrying Amount	$ 1,019,978	1,019,978
Accumulated Amortization	(455,192)	(360,891)
Impairment	(189,790)
Total	$ 374,996	659,087
Product rights | CAMBIA
Finite-Lived Intangible Assets [Line Items]
Remaining Useful Life (In years)	4 years
Gross Carrying Amount	$ 51,360	51,360
Accumulated Amortization	(31,027)	(25,891)
Total	$ 20,333	25,469
Product rights | Zipsor
Finite-Lived Intangible Assets [Line Items]
Remaining Useful Life (In years)	2 years 2 months 18 days
Gross Carrying Amount	$ 27,250	27,250
Accumulated Amortization	(22,044)	(19,707)
Total	$ 5,206	$ 7,543