Revenue from Contracts with Customers - Schedule of Impact of Changes in Accounting Standard (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Product and service	$ 18,045	$ 15,765
Collaboration	5,040	2,298
Total revenue	23,085	18,063
Net loss	$ (19,202)	$ (18,852)
Net loss per share - basic and diluted (in dollars per share)	$ (0.75)	$ (0.87)
Deferred revenue, current portion	$ 10,312		$ 9,229
Accumulated deficit	(333,058)		$ (313,102)
Difference between Revenue Guidance in Effect before and after Topic 606 | Accounting Standards Update 2014-09
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Product and service	238
Collaboration	0
Total revenue	238
Net loss	$ 238
Net loss per share - basic and diluted (in dollars per share)	$ 0.01
Deferred revenue, current portion	$ 516
Accumulated deficit	(516)
Calculated under Revenue Guidance in Effect before Topic 606
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Product and service	17,807
Collaboration	5,040
Total revenue	22,847
Net loss	$ (19,440)
Net loss per share - basic and diluted (in dollars per share)	$ (0.76)
Deferred revenue, current portion	$ 9,796
Accumulated deficit	$ (332,542)