GOODWILL AND INTANGIBLE ASSETS - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Mar. 31, 2020	Jun. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Jan. 31, 2020	Dec. 31, 2019
Goodwill [Line Items]
Gain (loss) on disposition of other assets			$ 59,495	$ 15,000
Finite-lived intangible assets			638,468			$ 652,734
Accumulated amortization			$ 211,296			$ 196,154
Gain on sale of nonfinancial assets		$ 15,000
Disposal Group, Disposed of by Sale, Not Discontinued Operations | Firdapse
Goodwill [Line Items]
Cash payment					$ 67,200
Gain (loss) on disposition of other assets	$ 59,500
Increase (decrease) in goodwill	(800)
Finite-lived intangible assets	32,200
Accumulated amortization	$ 31,600