Property and Equipment - Property and Equipment and Related Accumulated Depreciation and Amortization (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Property and Equipment, Gross	$ 84,570	$ 69,353
Less accumulated depreciation and amortization	(43,084)	(28,020)
Property and Equipment, Net	41,486	41,333
Lab Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and Equipment, Gross	34,727	27,883
Computer Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and Equipment, Gross	11,534	10,542
Software [Member]
Property, Plant and Equipment [Line Items]
Property and Equipment, Gross	5,429	3,703
Furniture and Office Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and Equipment, Gross	3,638	3,376
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property and Equipment, Gross	24,730	18,677
Construction in Process [Member]
Property, Plant and Equipment [Line Items]
Property and Equipment, Gross	$ 4,512	$ 5,172