RESTRUCTURING CHARGES - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Jun. 30, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Restructuring Cost and Reserve [Line Items]
Severance and benefit costs		$ 15,705	$ 3,891
Other exit costs		2,101	0
Restructuring liability		8,744	3,763	$ 1,578
December 2020 Plan
Restructuring Cost and Reserve [Line Items]
Severance and benefit costs		9,600
Other exit costs		1,600
Restructuring liability		7,200
Zyla Merger Reorganization
Restructuring Cost and Reserve [Line Items]
Severance and benefit costs		5,600
Other exit costs		200
Severance costs, share-based compensation		1,000
Restructuring liability		700
Reduction In Workforce Due To COVID-19
Restructuring Cost and Reserve [Line Items]
Severance and benefit costs	$ 300
Other exit costs	$ 300
2019 Plan
Restructuring Cost and Reserve [Line Items]
Severance and benefit costs		200	3,900
Restructuring liability		$ 800	$ 3,800