DISPOSITIONS (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended			9 Months Ended		12 Months Ended
	Jun. 30, 2016	Sep. 30, 2020	Sep. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2019
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Payments to acquire L-UDCA	$ 500
IPR&D asset		$ 259,537			$ 259,537					$ 245,802
Business combination-related contingent consideration	25,000	71,300			71,300					$ 70,900
Adjustments to contingent consideration					(10,268)	$ (4,329)	$ 1,000	$ (5,700)	$ (2,300)
Write off of L-UDCA IPR&D intangible asset		0	$ 0	$ 25,500	0	25,500
Write off of L-UDCA contingent consideration		$ 0	$ 0	18,000	$ 0	$ 18,000
Loss on write-off of L-UDCA				$ 7,500
Acquired Product Rights L-UDCA
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
IPR&D asset	$ 25,500
Business combination-related contingent consideration							$ 18,000