Property, plant and equipment, net - Summary of Property, Plant and Equipment Net (Detail) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Property Plant And Equipment [Line Items]
Total property, plant and equipment	$ 258,502	$ 215,455
Less accumulated depreciation and amortization	(25,639)	(15,849)
Property, plant and equipment, net	232,863	199,606
Land [Member]
Property Plant And Equipment [Line Items]
Total property, plant and equipment	1,210	1,210
Building [Member]
Property Plant And Equipment [Line Items]
Total property, plant and equipment	179,754	164,414
Computer Equipment and Software [Member]
Property Plant And Equipment [Line Items]
Total property, plant and equipment	6,790	5,134
Office Equipment [Member]
Property Plant And Equipment [Line Items]
Total property, plant and equipment	5,371	4,478
Laboratory Equipment [Member]
Property Plant And Equipment [Line Items]
Total property, plant and equipment	32,159	24,914
Leasehold Improvements [Member]
Property Plant And Equipment [Line Items]
Total property, plant and equipment	115	116
Construction in Progress [Member]
Property Plant And Equipment [Line Items]
Total property, plant and equipment	$ 33,103	$ 15,189