INTANGIBLE ASSETS AND GOODWILL - Narrative (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross	$ 969,308,000		$ 969,308,000
Finite-lived intangible assets, accumulated amortization	174,350,000		174,350,000		$ 110,889,000
Impairment losses	0	$ 0	0	$ 0
In-process research and development
Finite-Lived Intangible Assets [Line Items]
Impairment of intangible assets, finite-lived	$ 20,200,000	200,000,000	$ 20,200,000	200,000,000
In-process research and development | Armune Biosciences Agreement
Finite-Lived Intangible Assets [Line Items]
Impairment of intangible assets, finite-lived		9,700,000		9,700,000
Finite-lived intangible assets, gross		12,200,000		12,200,000
Finite-lived intangible assets, accumulated amortization		$ 2,500,000		$ 2,500,000