Revenue from Contracts with Customers - Schedule of Impact of Changes in Accounting Standard (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Product and service	$ 21,453	$ 16,915	$ 59,882	$ 50,990
Collaboration	7,163	10,101	16,818	28,682
Total revenue	28,616	27,016	76,700	79,672
Net loss	$ (16,486)	$ (11,404)	$ (56,290)	$ (34,811)
Net loss per share - basic and diluted (in dollars per share)	$ (0.56)	$ (0.45)	$ (2.09)	$ (1.50)
Deferred revenue, current portion	$ 8,905		$ 8,905		$ 9,229
Accumulated deficit	(370,146)		(370,146)		$ (313,102)
Accounting Standards Update 2014-09
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue recognized during period of adoption	(200)
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	181
Revenue recognized during period of adoption			(579)
Recognition of Deferred Revenue	0		0
Total revenue	181		579
Net loss	$ 181		$ 579
Net loss per share - basic and diluted (in dollars per share)	$ 0.01		$ 0.02
Deferred revenue, current portion	$ 175		$ 175
Accumulated deficit	(175)		(175)
Calculated under Revenue Guidance in Effect before Topic 606
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Product and service	21,272		59,303
Recognition of Deferred Revenue	7,163		16,818
Total revenue	28,435		76,121
Net loss	$ (16,667)		$ (56,869)
Net loss per share - basic and diluted (in dollars per share)	$ (0.57)		$ (2.11)
Deferred revenue, current portion	$ 8,730		$ 8,730
Accumulated deficit	$ (369,971)		$ (369,971)