REVENUE - Product Sales (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Disaggregation of Revenue [Line Items]
Total revenues	$ 34,565	$ 55,147	$ 76,099	$ 170,278
Gralise
Disaggregation of Revenue [Line Items]
Total revenues		$ 14,900	400	$ 46,000
Zyla Life Sciences
Disaggregation of Revenue [Line Items]
Product sales from acquiree	$ 3,400		$ 4,800