ORGANIZATION, BASIS OF PRESENTATION, AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Property and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 12,440	$ 35,869
Less: accumulated depreciation	(9,911)	(14,991)
Property and equipment, net	2,529	20,878
Depreciation expense	$ 7,000	6,700
Leasehold improvements
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	5 years
Property, plant and equipment	$ 3,944	21,633
Lab equipment
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	5 years
Property, plant and equipment	$ 5,459	8,471
Office furniture
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	5 years
Property, plant and equipment	$ 392	1,704
Manufacturing equipment
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	5 years
Property, plant and equipment	$ 395	1,890
Computer and office equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 1,595	1,606
Equipment held under capital leases
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	5 years
Property, plant and equipment	$ 270	204
Software
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	3 years
Property, plant and equipment	$ 385	$ 361
Minimum
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	3 years
Minimum | Computer and office equipment
Property, Plant and Equipment [Line Items]
Estimated Useful Lives		3 years
Maximum
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	5 years
Maximum | Computer and office equipment
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	5 years