Property and Equipment - Schedule of Property and Equipment (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 65,584	$ 73,653
Accumulated depreciation and amortization	(9,887)	(5,077)
Property and equipment, net	55,697	68,576
Leasehold Improvements
Property Plant And Equipment [Line Items]
Property and equipment, gross	49,028	47,609
Build-to-Suit Asset
Property Plant And Equipment [Line Items]
Property and equipment, gross	0	10,686
Construction in Progress
Property Plant And Equipment [Line Items]
Property and equipment, gross	1,868	4,682
Computer Equipment and Software
Property Plant And Equipment [Line Items]
Property and equipment, gross	3,323	3,049
Lab Equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross	5,801	3,019
Machinery and Equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross	3,890	2,980
Furniture and Fixtures
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 1,674	$ 1,628

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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