PROPERTY, PLANT, AND EQUIPMENT - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Property, plant and equipment
Depreciation	$ 19,500	$ 8,400	$ 52,900	$ 21,800
Property, plant and equipment, at cost	586,216		586,216		$ 532,956
Laboratory equipment
Property, plant and equipment
Property, plant and equipment, at cost	136,462		136,462		104,008
Assets under construction	9,700		9,700
Expected cost to complete project	2,000		2,000
Leasehold and building improvements
Property, plant and equipment
Property, plant and equipment, at cost	113,153		113,153		80,352
Assets under construction	8,400		8,400
Expected cost to complete project	13,300		13,300
Assets under construction
Property, plant and equipment
Property, plant and equipment, at cost	26,472		26,472		149,687
Computer software
Property, plant and equipment
Assets under construction	7,900		7,900
Expected cost to complete project	3,600		3,600
Furniture and fixtures
Property, plant and equipment
Property, plant and equipment, at cost	23,950		23,950		$ 14,539
Assets under construction	$ 500		$ 500