Property and Equipment, Net - Schedule of Property and Equipment, Net (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	$ 36,783	$ 38,494
Less: Accumulated depreciation	(34,514)	(32,027)
Total property and equipment, net	2,269	6,467
Lab Equipment [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	13,304	13,486
IT Equipment [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	3,781	3,853
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	19,392	20,790
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	$ 306	335
Construction in Process [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment, gross		$ 30

Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

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Amount before accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

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