Property, plant and equipment, net - Summary of Property, Plant and Equipment Net (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Property Plant And Equipment [Line Items]
Total property, plant and equipment	$ 223,159	$ 215,455
Less accumulated depreciation and amortization	(18,929)	(15,849)
Property, plant and equipment, net	204,230	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	165,562	164,414
Computer Equipment and Software [Member]
Property Plant And Equipment [Line Items]
Total property, plant and equipment	5,428	5,134
Office Equipment [Member]
Property Plant And Equipment [Line Items]
Total property, plant and equipment	4,808	4,478
Laboratory Equipment [Member]
Property Plant And Equipment [Line Items]
Total property, plant and equipment	28,291	24,914
Leasehold Improvements [Member]
Property Plant And Equipment [Line Items]
Total property, plant and equipment	116	116
Construction in Progress [Member]
Property Plant And Equipment [Line Items]
Total property, plant and equipment	$ 17,744	$ 15,189