Condensed Consolidated Financial Statement Details - Property and equipment, net (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Property and Equipment
Property and equipment — at cost:	$ 40,860	$ 39,537
Less: accumulated depreciation	(19,701)	(16,956)
Property and equipment, net	21,159	22,581
Machinery and laboratory equipment
Property and Equipment
Property and equipment — at cost:	14,040	13,762
Instruments
Property and Equipment
Property and equipment — at cost:	14,218	13,347
Office equipment
Property and Equipment
Property and equipment — at cost:	2,102	1,948
Leasehold improvements
Property and Equipment
Property and equipment — at cost:	$ 10,500	$ 10,480