ACQUISITIONS AND DISPOSITIONS - Sale of Gralise (Details) - USD ($)	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Jan. 10, 2020
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Co-promotion service income	$ (3,325,000)	$ (609,000)
Gralise | Disposal Group, Disposed of by Sale, Not Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Consideration received, including base purchase price and inventory adjustment			$ 78,600,000
Consideration received, base purchase price			75,000,000.0
Consideration received, inventory adjustment upon disposal			$ 3,600,000
Consideration receivable as percentage of net sales after closing			75.00%
Threshold for consideration receivable on net sales after closing			$ 70,000,000.0
Net sale after closing, contingent consideration			$ 52,500,000
Gain (loss) on disposal	127,500,000
Upfront consideration received	78,600,000
Contingent consideration deemed to be probable	52,500,000
Inventory transfer	3,600,000
Co-promotion service income	$ 1,300,000