REVENUE - Schedule of Disaggregated Revenue from Contracts with Customers (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Disaggregation of Revenue [Line Items]
Total revenues	$ 20,617	$ 57,203	$ 41,534	$ 115,132
Total product sales, net
Disaggregation of Revenue [Line Items]
Total revenues	20,165	25,937	29,417	52,387
CAMBIA
Disaggregation of Revenue [Line Items]
Total revenues	7,780	6,758	14,054	15,566
Zipsor
Disaggregation of Revenue [Line Items]
Total revenues	3,535	1,524	5,866	5,755
INDOCIN products
Disaggregation of Revenue [Line Items]
Total revenues	5,434	0	5,434	0
SPRIX Nasal Spray
Disaggregation of Revenue [Line Items]
Total revenues	1,602	0	1,602	0
SOLUMATRIX products
Disaggregation of Revenue [Line Items]
Total revenues	836	0	836	0
OXAYDO
Disaggregation of Revenue [Line Items]
Total revenues	517	0	517	0
Gralise
Disaggregation of Revenue [Line Items]
Total revenues	(116)	17,800	431	31,078
NUCYNTA and Lazanda product sales adjustments
Disaggregation of Revenue [Line Items]
Total revenues	577	(145)	677	(12)
Commercialization agreement, net
Disaggregation of Revenue [Line Items]
Total revenues	0	31,003	11,258	61,859
Royalties and milestone revenue
Disaggregation of Revenue [Line Items]
Total revenues	$ 452	$ 263	$ 859	$ 886