Balance Sheets Details - Property and Equipment, net (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Property and equipment	$ 40,389	$ 39,533
Less: accumulated depreciation and amortization	(33,567)	(33,251)
Property and equipment, net	6,822	6,282
Laboratory equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment	24,717	23,561
Leasehold improvements [Member]
Property, Plant and Equipment [Line Items]
Property and equipment	10,774	10,804
Computer equipment and software [Member]
Property, Plant and Equipment [Line Items]
Property and equipment	3,135	3,016
Office equipment and furniture [Member]
Property, Plant and Equipment [Line Items]
Property and equipment	1,115	1,461
Construction in progress [Member]
Property, Plant and Equipment [Line Items]
Property and equipment	$ 648	$ 691

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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