FAIR VALUE MEASUREMENTS - Fair Value of Level 3 (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at January 1	$ 93,000
Balance at December 31	70,900	$ 93,000
Significant unobservable inputs (Level 3)
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at January 1	93,000	90,000
L-UDCA write-off	(18,000)	0
Increase from revaluation of contingent consideration	15,051	11,590
Contractual Payments	(6,696)	(6,373)
Contractual Payments accrued at December 31	(12,253)	(2,171)
Foreign currency impact	(202)	(46)
Balance at December 31	$ 70,900	$ 93,000