GOODWILL AND INTANGIBLE ASSETS - Additional Information (Detail) - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Jan. 31, 2020
Goodwill And Intangible Assets [Line Items]
Gain (loss) on disposition of other assets		$ 0	$ 59,495,000	$ 25,000,000
Finite-lived intangible assets		677,350,000	644,087,000
Accumulated amortization		288,698,000	$ 226,816,000
Goodwill impairment charge		0
Finite lived intangible assets		388,652,000
License payments
Goodwill And Intangible Assets [Line Items]
Finite lived intangible assets		6,203,000
License payments | Voxzogo
Goodwill And Intangible Assets [Line Items]
Finite lived intangible assets		$ 6,000,000
Disposal Group, Disposed of by Sale, Not Discontinued Operations | Firdapse
Goodwill And Intangible Assets [Line Items]
Consideration received					$ 67,200,000
Gain (loss) on disposition of other assets	$ 59,500,000
Decrease in goodwill	800,000
Finite-lived intangible assets	32,200,000
Accumulated amortization	$ 31,600,000
Medivation
Goodwill And Intangible Assets [Line Items]
Milestone payments received				$ 25,000,000