ACQUISITIONS AND DISPOSITIONS - Sale of NUCYNTA (Details) - Disposal Group, Disposed of by Sale, Not Discontinued Operations $ in Millions	1 Months Ended	3 Months Ended
	Feb. 11, 2020 USD ($)	Mar. 31, 2020 USD ($)	Feb. 13, 2020 USD ($) payment	Jan. 10, 2020 USD ($)
Gralise
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Consideration received, including base purchase price, inventory adjustment and royalties received				$ 78.6
Proceeds from divestiture of businesses, base purchase price				75.0
Proceeds from divestiture of businesses, inventory amount				$ 3.6
Gain (loss) on disposal		$ 127.5
Consideration received		78.6
Contingent consideration deemed to be probable		52.5
Inventory transfer		3.6
NUCYNTA
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Consideration received, including base purchase price, inventory adjustment and royalties received			$ 367.9
Proceeds from divestiture of businesses, base purchase price			375.0
Proceeds from divestiture of businesses, inventory amount			$ 6.0
Royalties received	$ 13.1
Number of lump sum payments | payment			2
Gain (loss) on disposal		(15.8)
Consideration received		367.9
Accrued third-party consent fees		9.0
Carrying value of intangible derecognized		369.1
Inventory transfer		$ 5.6
NUCYNTA | Third-Party Consent Agreement
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Lump sum payments obligation			$ 4.5