PROPERTY, PLANT, AND EQUIPMENT - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Property, plant and equipment
Depreciation	$ 17,600	$ 7,100	$ 33,400	$ 13,400
Property, plant and equipment, at cost	573,665		573,665		$ 532,956
Laboratory equipment
Property, plant and equipment
Property, plant and equipment, at cost	130,323		130,323		104,008
Assets under construction	11,500		11,500
Expected cost to complete project	2,900		2,900
Leasehold and building improvements
Property, plant and equipment
Property, plant and equipment, at cost	111,778		111,778		80,352
Assets under construction	43,900		43,900
Expected cost to complete project	6,700		6,700
Computer equipment and computer software
Property, plant and equipment
Property, plant and equipment, at cost	74,447		74,447		65,323
Assets under construction
Property, plant and equipment
Property, plant and equipment, at cost	61,628		61,628		149,687
Computer software
Property, plant and equipment
Assets under construction	5,600		5,600
Expected cost to complete project	2,000		2,000
Furniture and fixtures
Property, plant and equipment
Property, plant and equipment, at cost	22,698		22,698		$ 14,539
Assets under construction	$ 600		$ 600