Property and Equipment, Net - Schedule of Property and Equipment, Net (Detail) $ in Thousands	Dec. 31, 2018 USD ($)
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	$ 36,783
Less: Accumulated depreciation	(34,514)
Total property and equipment, net	2,269
Lab Equipment [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	13,304
IT Equipment [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	3,781
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	19,392
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	$ 306

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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