Balance Sheets Details - Property and Equipment, net (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment, Net, by Type [Abstract]
Property and equipment	$ 37,852	$ 35,069
Less: accumulated depreciation and amortization	(33,093)	(32,254)
Property and equipment, net	4,759	2,815
Laboratory equipment
Property, Plant and Equipment, Net, by Type [Abstract]
Property and equipment	21,328	19,777
Equipment retired during period	300	200
Leasehold improvements
Property, Plant and Equipment, Net, by Type [Abstract]
Property and equipment	10,359	10,327
Computer equipment and software
Property, Plant and Equipment, Net, by Type [Abstract]
Property and equipment	3,954	3,695
Office equipment and furniture
Property, Plant and Equipment, Net, by Type [Abstract]
Property and equipment	1,272	1,185
Construction in progress
Property, Plant and Equipment, Net, by Type [Abstract]
Property and equipment	$ 939	$ 85

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 of divestiture of long-lived, 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, furniture and fixtures, and computer equipment.

+ References

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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.

+ References

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