Property Plant and Equipment Net (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Property Plant And Equipment [Abstract]
Laboratory equipment	$ 40,462	$ 37,303
Computer equipment and software	9,608	9,650
Furniture and fixtures	5,844	6,002
Leasehold improvements	50,612	45,362
Land	9,080	9,080
Construction in progress	133,645	68,182
Property, Plant and Equipment Gross	249,251	175,579
Less: accumulated depreciation	(67,351)	(61,007)
Property, Plant and Equipment, Net	$ 181,900	$ 114,572