FINANCING ARRANGEMENTS - Schedule of Accretion of Vatera Principal Term Loan and Future Payments (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2019 USD ($)
Accretion and Future Payments of Term Loan [Roll Forward]
Beginning Balance	$ 110,476
Ending Balance	89,076
Senior Subordinated Convertible Loan Agreement
Accretion and Future Payments of Term Loan [Roll Forward]
Paid-in Kind Interest	12,813
Accretion Expense	15,114
Principal Payments and Exit Fee	(93,718)
Senior Subordinated Convertible Loan Agreement \| February 25 - September 30, 2019
Accretion and Future Payments of Term Loan [Roll Forward]
Beginning Balance	66,234
Paid-in Kind Interest	1,234
Accretion Expense	1,079
Principal Payments and Exit Fee	0
Ending Balance	68,104
Senior Subordinated Convertible Loan Agreement \| October 1 - December 31, 2019
Accretion and Future Payments of Term Loan [Roll Forward]
Beginning Balance	68,104
Paid-in Kind Interest	530
Accretion Expense	494
Principal Payments and Exit Fee	0
Ending Balance	69,128
Senior Subordinated Convertible Loan Agreement \| Year Ending December 31, 2020
Accretion and Future Payments of Term Loan [Roll Forward]
Beginning Balance	69,128
Paid-in Kind Interest	2,098
Accretion Expense	2,094
Principal Payments and Exit Fee	0
Ending Balance	73,320
Senior Subordinated Convertible Loan Agreement \| Year Ending December 31, 2021
Accretion and Future Payments of Term Loan [Roll Forward]
Beginning Balance	73,320
Paid-in Kind Interest	2,146
Accretion Expense	2,364
Principal Payments and Exit Fee	0
Ending Balance	77,830
Senior Subordinated Convertible Loan Agreement \| Year Ending December 31, 2022
Accretion and Future Payments of Term Loan [Roll Forward]
Beginning Balance	77,830
Paid-in Kind Interest	2,201
Accretion Expense	2,666
Principal Payments and Exit Fee	0
Ending Balance	82,697
Senior Subordinated Convertible Loan Agreement \| Year Ending December 31, 2023
Accretion and Future Payments of Term Loan [Roll Forward]
Beginning Balance	82,697
Paid-in Kind Interest	2,257
Accretion Expense	2,999
Principal Payments and Exit Fee	0
Ending Balance	87,953
Senior Subordinated Convertible Loan Agreement \| Year Ending December 31, 2024
Accretion and Future Payments of Term Loan [Roll Forward]
Beginning Balance	87,953
Paid-in Kind Interest	2,311
Accretion Expense	3,362
Principal Payments and Exit Fee	0
Ending Balance	93,626
Senior Subordinated Convertible Loan Agreement \| Year Ending December 31, 2025
Accretion and Future Payments of Term Loan [Roll Forward]
Beginning Balance	93,626
Paid-in Kind Interest	36
Accretion Expense	56
Principal Payments and Exit Fee	(93,718)
Ending Balance	$ 0

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